5.34 · Khorasan Institute of Higher Education. Abstract .... tive designs of the motor and the power ele ctron- ..... high mechanical requirements at Mega-Speeds.
Facts 2001 – 2007 and Future
Power and control electronics, machine stator and shaft of the 100 W, 500 000 rpm drive system; furthermore shown: 100 W, 1 000 000 rpm machine.
2
Appendix I PES Current PhD Projects
Daniel Aggeler Future compact distribution substations drilling robots will demand medium voltage DC-DC power conversion. Present medium voltage switching devices are restricted to a low switching frequency, therefore a compact, low weight solution is not possible. New wide band gap materials offer the possibility to achieve both high frequency and voltage operation. This research project uses a new SiC JFET switch to construct a 50 kHz, 25 kW Dual Active Bridge isolated DC-DC converter with input and output voltages of 5 kV and 700 V. A new high voltage switch is developed using 5 SiC JFETs connected in a cascade/cascode configuration with a low-voltage MOSFET. Static and dynamic experimental measurements show excellent high frequency switching performance up to 5 kV. For achieving a transient and dynamic stable balancing of the voltages between the series connected JFETs, the leakage currents are investigated and controlled with passive circuits. A dynamic model of the SiC JFET, which enables an accurate simulation of switching actions, is developed. The high frequency, high voltage transformer will also be examined where the transient voltage distribution and the design of the parasitic components are challenging. Due to the high operating frequency and the low SiC JFET losses a power density of 4.8 kW/dm3 and an efficiency of 97 % could be achieved for the 25 kW prototype.
Starting date: June 2006
Funding: Industry/ETH
3D-CAD of the bi-directional 5 kV/700 V Dual Active Bridge DC-DC converter employing cascaded SiC JFETs/MOSFET cascade switches in the input stage.
J4
SiC JFET cascade turn-on and turn-off voltage distribution for 5 kV supply.
6300
Voltage [V]
Medium voltage high frequency DC-DC converter
V J4,DS
4500
J3
V J3,DS 2700
V J2,DS
900
V J1,DS
J2 J1
-900
0
2.5
5 Time [us]
10
7.5
Uwe Badstuebner Besides high power density, industrial DC-DC converter applications are strongly demanding increased power conversion efficiency. There, phase shift and series-parallel resonant converter topologies are the most suitable, since they operate with soft-switching thus reducing switching losses and/or allowing high switching frequencies for minimizing the passive components’ volume. In order to compare different DC-DC converters for maximum efficiency and power density, a comprehensive optimization procedure, which considers the complete converter system including topology, semiconductors, cooling system, and transformer geometry, is necessary. Based on analytical models for each individual component the developed procedure determines the optimal operating point and component values. The highest possible power density, 19.1 kW/dm3 (excluding air space requirements), is achieved with the series-parallel resonant converter with capacitive output filter (SPR-C). With the resulting optimized parameters, a 5 kW, 400 V-to-48 V, isolated SPR-C of 10.2 kW/dm3 power density has been constructed. The future challenge is to reverse the optimization program, i. e. to determine to required material characteristics and technologies that could enable a further improvement of the converter performance.
26
Starting date: January 2007
Funding: Industry/ETH
Prototype of the optimized series-parallel resonant converter with capacitive output filter. Input voltage 400 V, output voltage 48...54 V, output power 5 kW, power density 10.2 kW/dm3.
Power density comparison of the phase shift converter with capacitive output filter (CTC), and current doubler (CDR) output, and the seriesparallel resonant converter with capacitive output filter (SPR-C) in dependency of the switching frequency. Air space between components required for mounting and insulation is not considered.
20 power density PD [kW/dm3]
Ultra compact ultra efficient DC-DC converter systems
SPR-C CTC 15
10 CDR 5
30
50 100 300 500 switching frequency fs [kHz]
1000
Martin Bartholet Starting date: April 2005 Funding: KTI/Industry
Drive and bearing winding configuration of a 600 W bearingless slice motor. A maximum speed of 8 000 rpm with a flow and pressure of 50 l/min and 3bar can be achieved with this temple-type design.
Schematic of a two-phase bearingless slice motor configuration in conjunction with the novel interleaved half-bridge topology allowing the implementation of integrated three-phase power modules.
Optimized inverters for levitated machines
State-of-the-art bearingless slice motor (BSM) pump systems are used in areas such as the semiconductor industry and for medical applications. To address new markets in the chemical and biotechnology industries, more cost effective designs of the motor and the power electronics must be achieved. By performing a complete analysis of the total motor drive system a 50 % price and volume reduction of the power electronics, compared to today’s systems, has been achieved while offering the same control flexibility. In addition to the new power electronics configuration, novel modulation concepts have been developed. Furthermore, an overall performance comparison has revealed a lower complexity motor configuration as a promising approach for future BSM systems.
Dominik Bortis Starting date: June 2005 Funding: Industry
AC 208V ± 10% 400V ± 10% 480V ± 10%
C0 DC
vC0 Ppulse = 20MW Pavg = 20kW
Pulse modulator supplied by unity power factor AC-DC converter with wide input voltage range and variable output voltage
Three-phase sinusoidal input current buck+boost AC-DC converter employing digital control for constant power consumption at pulsating load; specifications: Pout=25 kW, Vin=208...480 V, Vout=150 V...450 V.
Solid state pulsed power system
Pulsed power systems are employed in linear accelerators for cancer treatment, water sterilization, and semiconductor ionization systems. The medical applications have demanding specifications for the pulse shape, overshoot, flatness and energy. Existing pulse generators/modulators typically use a pulse forming network that is switched by a thyratron, followed by a step-up pulse transformer. This research work is replacing the tube technology with modern power semiconductors. A new solid state pulse modulator, generating 5 to 10 µs, 20 MW pulses with an average power of 20 kW, is in the final stage of construction. A custom pulse transformer generates the 200 kV/100 A pulse on the secondary side. On the primary side, 1 kV/20 kA pulses are produced by 4 parallel connected switch units, each consisting of a DC capacitor bank and a high power 1700 V/3.6 kA IGBT-Module. Analytical modeling is used to design the transformer with the correct parasitic inductance and capacitance in order to produce the desired pulse shape. The modulator power is supplied by a 25 kW, threephase unity power factor AC-DC converter that is capable of operating over wide input and output voltage ranges. A new control strategy is implemented to draw constant power from the mains even while supplying the pulsating load.
27
Luca Dalessandro Optimal modulation and wideband current sensing for three-level PWM rectifiers
For high power, three-phase rectifiers a unity power factor input is becoming an industrial requirement. Three-level PWM rectifiers are of special interest as they offer, besides the unity power factor, a reduced input current ripple and lower switching device blocking voltages. The selection of an appropriate current control technique is required to achieve sinusoidal input currents. This research deals with innovative and optimal pulse-width modulation strategies for threephase, three-level rectifiers. Both direct and indirect modulation strategies have been analyzed and implemented. In addition, accurate but lowcost current sensors are necessary for the commercial implementation of current controlled converters. For modern, high switching frequency converters, a wide bandwidth is the most important current sensor characteristic. A novel, highperformance, isolated current sensor, comprised of a planar current transformer and a Hall-effect element, has been designed and tested up to 30MHz. A non-linear model of gapped current transformers, based on the capacitance-permeance analogy, has been additionally developed.
Starting date: September 2002 Funding: ETH
DC planar current transformer capable of measuring up to 40 ADC with a bandwidth of 30 MHz.
VR
iR
VRM
Steady state operation of a three-level, three-phase Vienna Rectifier with discontinuous modulation; operating parameters: 115 V/ 50 Hz input and 1.8 kW output power. Waveforms are input phase voltage (200 V/div), input current (5 A/div), rectifier input voltage (200 V/div) and midpoint current (10 A/div). Time base: 2 ms/div.
iM
Thomas Friedli Ultra Sparse Matrix Converters
Indirect Sparse Matrix Converters are a minimum switch count two-stage realization of three-phase AC-AC converters that contain no intermediate link energy storage elements. Therefore, higher power densities and longer service life are possible. These converters are inherently bi-directional and have applications in lift/escalator systems and aircraft motor drives. In aircraft applications only unidirectional power flow is demanded. Accordingly, the unidirectional Ultra-Sparse Matrix Converter (USMC) is of high interest. A challenging aspect of the research on the USMC is to develop a highly responsive motor controller when faced with unidirectional power flow capability and/or restricted phase-angle operation and high system order resulting from the EMI input filter. Furthermore, advanced modulation schemes especially suitable for a realization of the input stage power transistors in SiC technology are derived and verified on a high switching frequency laboratory model. For realizing the system prototype, special attention is paid to the arrangement of the passive power components and the power semiconductors in order to minimize the parasitic coupling of the EMI filter components. Finally, this research will perform a comprehensive comparison between the Sparse Matrix Converter, and the back-to-back VSI and CSI for equal total silicon device area. 28
Starting date: September 2005 Funding: Industry/ETH
5.5 kVA Ultra-Sparse Matrix Converter capable of operating up to output stage switching frequencies of 50 kHz. Incorporates the auxiliary power supply, a compact optimal heat sink and EMI filter.
Steady state operation of the Ultra-Sparse Matrix Converter showing the DC link voltage, the input 50 Hz current and the output 120 Hz current waveforms. Time scale: 5ms/div, DC link voltage u: 200 V/div, input phase current ia: 1 A/div, output phase current iA: 2 A/div.
Florian Giezendanner Optimization of electronic ballasts for fluorescent lamps Starting date: November 2005 Funding: Industry/ETH Non-dimmable 35 Watt electronic ballast for T5 fluorescent lamps.
Screenshot of the inductor optimization program, showing the distribution of the losses in the inductor winding.
Electronic ballasts for fluorescent lamps have replaced electromagnetic ballasts in most applications because of their higher efficiency and the improved light quality. Electronic ballasts are cost sensitive products and therefore standard circuit topologies are used by the majority of manufacturers. Worldwide research has focused on alternative circuit topologies for electronic ballasts; however, the proposed topologies either do not offer a significant cost advantage or fail to provide the required performance. The goal of this project is to optimize the standard circuit topology consisting of a boost PFC stage and a resonant half-bridge inverter. An analytical and approximate numerical model is developed for the losses in the magnetic components and the semiconductor switches, the thermal behavior and the conducted EMI noise spectrum. Each part of the total circuit is first modeled, implemented and verified in a standalone Java program. Ultimately, all partial programs are combined into a complete design and optimization program.
Guanghai Gong Starting date: June 2002 Funding: ETH
Output voltage and output current of an isolated multi-cell cascaded hybrid power amplifier; specifications: 1.2 kW output power, ± 380 V output voltage range, DC ~ 7 kHz bandwidth, 100 V/ µs maximum slew rate, and 84 % efficiency at maximum output power.
1.2 kW laboratory model of the hybrid power amplifier formed by series connection of 9 AM inverter cells and a high slew rate linear power amplifier; power supply of the converter cells is via an unregulated bidirectional multi-output series resonant converter.
Testing AC Power Sources based on hybrid amplifiers
AC power sources are an essential piece of the test equipment required for the development and certification of AC mains connected power electronic systems. Presently, linear power amplifiers are mainly utilized due to their high fidelity and excellent dynamic behavior. However, they have very high losses, which make the systems bulky and expensive. This research work is to develop high efficiency, high bandwidth and high fidelity AC power sources using hybrid power amplifiers. Hybrid amplifiers combine both linear power amplifiers and switch-mode converters into a single system. The first hybrid topology utilizes a three-level buck+boost converter as an envelope tracking power supply for a linear power amplifier. A 1 kW laboratory prototype has been built to verify the theoretical analysis. The second hybrid power amplifier comprises of a high slew rate linear power amplifier and 9 series connected H-bridges cells. Based on the theoretical calculations and digital simulations, a 1.2 kW hardware system has been built and is now in the testing phase.
29
Michael Hartmann Ultra-compact three-phase three-level rectifiers
Starting date: March 2007
Funding: Industry/ETH
To substantially increase the power density of active three-phase rectifiers the switching frequency has to be increased considerably. Previous research has shown that an optimum power density of 24 kW/dm3 could be achieved for a water-cooled rectifier if the switching frequency is pushed to 2.1 MHz. The aim of this research is the realization of an active three-phase rectifier operating at 2.5 MHz based on ultra-fast switching devices (RF-MOSFETs, and SiC-components) that will lead to a total power density of greater than 20 kW/dm3. To optimize the switching behavior, all semiconductors devices are included in a customized power module and a specific damping layer wiring concept is used for minimizing EMI, transient overvoltages and current ringing. In addition, high-speed digital current control is employed to ensure high input current quality. The current controller (including ns resolution PWM and 40 MSa/s measurements) is implemented in an enhanced FPGA with host DSP. In a first step, a 10 kW rectifier with a 1 MHz switching frequency is under construction in order to evaluate the switching behavior and the digital control concept.
400 kHz, 10 kW, three-phase, three-level, unity power factor rectifier with forced air cooling; power density: 8.5 kW/dm3; specifications: input voltage range of 90–480 V, input frequency range up to 800 Hz, output voltage controlled to 800 V.
Power density trends for power electronic converters. The basic AC-AC, AC-DC, DCDC converter types have power density barriers in the range of 20 to 40 kW/cm3. To increase the barriers will require major improvements in cooling system and passive component technology.
Marcelo Heldwein EMC Filtering of three-phase PWM converters
In modern power electronic systems high switching frequencies are employed to increase power density, but EMC filtering components are still responsible for a major portion (approx. 30 %) of the total volume. Therefore, the volumetric reduction of the EMI filter components is of paramount importance. The main objectives of this research are techniques for modeling the generation and propagation of conducted noise in three-phase PWM converters and EMC filter design procedures that ultimately ensure compliance to EMC standards and minimize the EMC filter volume. For supporting the experimental evaluation of the filter designs, novel measurement devices that allow a separation of the common-mode and differential-mode conducted emissions are developed. Furthermore, detailed models of filter components are derived and employed in an automated design procedure for three-phase EMC filters. Furthermore, active common-mode filters with very low earth leakage current are proposed and investigated, and techniques for the cancellation of parasitic capacitances of three-phase common mode inductors are proposed and successfully implemented.
30
Starting date: March 2003
Funding: ETH/Industry
Calculated volume of the common mode EMI filter as a function of switching frequency and capacitance to ground.
Active common mode filter with minimal passive components and a discrete high frequency amplifier.
Philipp Imoberdorf Starting date: April 2006 Funding: ETH
Active Magnetic Bearing consisting of a high frequency stator iron with four poles, a radially magnetized permanent magnet ring and the copper coils.
Radial position measurement for a rotor with a diameter of 3 mm: Sensor output for a rotor displacement of 0.5 mm from the origin in all directions. The noise level is ± 5 µm.
XY Measurement - Orbit
Y - Direction
0.5 mm
0 mm
Active Magnetic Bearing for Mega-Speed Drive systems
Mega-Speed (1 million rpm) and high-powerdensity drives are attracting more and more interest for various applications. For example, they can be used in portable power, mesoscale gas turbine systems and turbocompressors for fuel cells. In all Mega-Speed machines, the bearing is the limiting technology. At such high rotational speeds, standard ball bearings have significant frictional losses and a limited lifetime. These drawbacks can be avoided by utilizing air or magnetic bearings. With an active magnetic bearing, the possibility of active control of the bearing forces is a main advantage but it comes with the drawback of requiring a complex position controller. Further challenges in the design are the evacuation of the heat (air friction, copper and iron losses), identification of the critical rotor speeds and the control strategies to damp vibrations induced by eccentricity. Miniaturization and integration of a radial and axial bearing is under investigation in order to cope with the high mechanical requirements at Mega-Speeds. Presently, a first test-bench is ready for measurements which combines a 1 kW, 500 000 rpm drive system with an active magnetic bearing system.
-0.5 mm -0.5 mm
0 mm
0.5 mm
Philipp Karutz Starting date: January 2006
Funding: KTI/Industry
Illustrated cut-through-view of an industry spinning process that is hermetically sealed within a process chamber, using magnetic bearing technology for the levitation of the rotor.
Photograph of the fully assembled laboratory prototype with bearing and drive windings.
Levitated, contactless machines for the process industry
Several processes in the chemical, pharmaceutical, biotechnology and semiconductor industry require an electrical machine that provides contactless levitation and rotation through a hermetically sealed chamber wall. This research deals with a novel concept that combines key advantages such as high acceleration capability, a large air gap and a compact motor setup. The basic idea is to separate the homopolar bearing unit axially from the multipolar drive unit. The goal of the research is the formulation of design criteria for such a system based on analytical formulations and computer aided 3D FEM simulations, resulting in a comparison with other concepts and the implementation of a prototype. A first laboratory prototype has been built and this achieves the desired design specifications and matches the simulation results accurately.
31
Daniel Krähenbühl Mesoscale electric power generation from pressurized gas flow (Air-to-Power)
Starting date: June 2007
Funding: ETH/Industry
A mesoscale system for converting pressurized gas flow into electric power is a promising solution for recovering energy from pressure reduction processes, e.g. pressure reduction valves, conventional throttles in automotive applications or turbo expanders in cryogenic plants. Such a device could supply power to sensors and actuators of industrial robots and thereby reduce the requirement for electrical power distribution. The disadvantages of existing systems are their poor power density and the large inlet flow rate that is required for maximum power output. This research will result in an ultra compact (20 x 50 mm) Air-to-Power demonstrator that produces an electrical output of 100 W while operating from a compressed air input source with a pressure of 3 to 8 bar. This new, compressed-air-to-electricpower system comprises of an axial-impulse turbine, a permanent magnetic generator and the power and control electronics. At maximum power output the speed of the axial-impulse turbine is approximately 350 000 rpm.
Solid model of an ultra compact (20 mm x 50 mm) air-topower system; specifications: 100 W output power, 3...8 bar air supply, 350 000 rpm rated speed, regulated 24 VDC output.
Solar Impulse airplane turbo compressor unit modified into an air-to-power system; PM generator with stator guide vanes, radial flow turbine, and spiral air inlet.
Florian Krismer Ultra compact isolated bidirectional DC-DC converter
During the last decade, there has been a trend in the automotive industry towards the development of alternative vehicles, such as hybrid and fuel cell cars. There, high voltage systems are required since the conventional 14 V system is inadequate to handle the high power demand. This research investigates bidirectional DC-DC converter systems to transfer up to 2 kW between the high and low voltage buses. Automotive requirements of compactness, low weight, galvanic isolation, and high efficiency (>90 %) restrict the possible circuit topologies. The selected converter type is a Dual Active Bridge (DAB). The challenge of the project is to achieve the required efficiency and power density since the converter must switch over 200 A on the 14 V side. This problem is systematically approached by employing an optimal design and a minimum loss modulation scheme. A performance comparison of different converter prototypes is also a major part of this work. A 2 kW DAB and series resonant converter prototype have been built for a low battery voltage range of 11 V to 16 V and fuel cell voltages between 240 V and 450 V. At rated power, a maximum DAB converter efficiency of 92 % has been achieved.
32
Starting date: October 2004 Funding: Industry/ETH
3D FEM simulation for optimizing the layout of the high current PCB of the low voltage converter side for 100 kHz switching frequency.
Prototype of the Dual Active Bridge DC-DC converter with water cooling; low voltage side (left) 11 V ... 16 V, high voltage side (right) 240 V ... 450 V, switching frequency: 100 kHz, rated power: 2 kW, power density: 1.5 kW/dm3.
Johann Miniböck Starting date: April 2001 Funding: Industry/ETH
3D CAD model of a proposed 2.5 MHz switching frequency, three-level three-phase 10 kW VIENNA Rectifier. With water cooling the estimated power density is 18.5 kW/liter. Dimensions: 120 mm x 90 mm x 50 mm.
Phase current waveform of a 400 kHz three-phase, three-level rectifier supplying a 2.4 kW load from a 800 Hz 115 V input supply. Time base: 200 µs/div, phase voltage uN: 50 V/div, phase current iN: 5 A/div, DSP measured current: 0.5 V/div, current controller output: 0.5 V/div..
Three-phase three-level PWM rectifiers
Applications in telecommunications and aircraft systems demand high power density, unity power factor rectifier systems in the power range of 5 to 20 kW. For determining the best rectifier concept, a comprehensive comparison of unidirectional three-phase rectifier topologies has been undertaken based on input current power factor, current distortion and component stress factors. There, the three-level Vienna Rectifier was identified as the best topology. A main aspect of the research on the system is the development of novel current control concepts for guaranteeing unity power factor operation also in case of a heavily unbalanced mains or a mains phase loss. Furthermore, an innovate single current sensor control technique is proposed and the EMI filter volume is minimized through the coupling of the output center point back to an artificial mains star point formed by the differential-mode EMI filter capacitors. Finally, a novel balancing scheme for a cascaded two-stage isolated DC/DC converter system connected to the rectifier output is proposed. All theoretical considerations are extensively verified by experiments on system prototypes of different power levels and at medium and high switching frequencies.
Kazuaki Mino Starting date: January 2002
D1 T1 Tr1
Tr2
Tr3 Uo
Funding: Industry
Hybrid 12-pulse rectifier for aircraft applications consisting of two 6-pulse rectifiers, supplied by a line interface transformer, and a boost stage on each rectifier output.
D2 T2
ua’b’ L1 ua
L uab 2 ub
L3 uc
Three-phase line current waveforms for the hybrid 12-pulse rectifier operating with constant switch duty cycle and optimal duty cycle control. With optimal switch control, an ideal sinusoidal shape can be achieved for the line currents.
Hybrid three-phase rectifiers
Diode bridge rectifiers still find extensive applications in industry due to their low costs and high robustness. However, the output voltage of passive rectifiers is unregulated and high amplitude low frequency harmonics are present in the mains current. Accordingly, these rectifiers do not meet certain power factor and harmonic standards. This research investigates solutions that add a minimum number of switches to improve the rectifier bridge input current spectrum and/or to provide output voltage control. Two topologies are investigated; the electronic inductor and a hybrid 12-pulse rectifier. The electronic inductor comprises a high switching frequency, low-voltage full-bridge, a capacitor, and a switching frequency inductor and is employed in a 5 kW three-phase rectifier for replacing the bulky passive output inductor. This results in an overall system power density of 10kW/dm3 and a power conversion efficiency close to 99 %. In aircraft applications, multi-pulse rectifiers are the state-of-the-art solution, but they suffer from a non-constant output voltage, and excessive harmonics for unbalanced mains. Here, the proposed addition of two switches, and a closed loop current control in combination with a novel space vector modulation technique provides controlled constant output voltage and sinusoidal input currents as verified for a 10 kW hybrid 12-pulse rectifier prototype. 33
Andreas Müsing To design a new converter the modern power electronics engineer must deal with multiple issues including circuit topologies, control methods, thermal management systems and EMC. Therefore, a software tool is required that can link together the interactions between the multi-physics, multi-domain world in order for the engineer to produce a design that will work as predicted the first time it is constructed. The ultimate goal is to provide the engineer with a complete virtual prototyping platform. Given rising switching frequencies and increasing power densities of converter systems, EMI due to PCB stray parasitics becomes a dominating effect that cannot be neglected in the design process. The main goal of this research is to develop a tool that is able to predict the system behavior concerning EMI effects and over-voltages due to parasitic components with high accuracy. The Partial Element Equivalent Circuit (PEEC) method has proven to be a highly suitable EM solver for this application, and simulations of PCB layout parasitics have shown an excellent agreement with measurements. Future research activities include full 3D PEEC modeling that can include the EMI effect of heat sinks and the parasitic couplings of EMI filter components.
Starting date: April 2006 Funding: ETH
Simulation and measurement of the DM conducted emissions of a three-phase AC-AC indirect Matrix Converter. Parasitic capacitive and inductive couplings as obtained from PEEC simulation are considered.
85 80 Emission level [dBµV]
Power converter parasitics extraction employing the PEEC method
75
CISPR class A limit
70 65
DM CE measurement
60 55 50
DM simulation
45 10
6
10
7
Frequency[Hz]
Screenshot of the PEEC simulation design environment, showing the model of an eddy current position sensor for an Active Magnetic Bearing System.
Hanna Plesko Multi-functional drive system with integrated auxiliary DC-DC converter
In hybrid vehicles, which are attracting significant attention due to increasing fuel costs and air pollution, the electric energy distribution system occupies a significant share of the overall volume and costs. Most of the conventional hybrid electric vehicles use two different voltage levels for feeding high power and low power loads. The high voltage and low voltage systems are interconnected via an isolated bidirectional DC-DC converter. In order to minimize the realization effort, two new concepts for integrating the DC-DC converter function into the inverter and drive system are investigated analytically and experimentally. Starting from a Dual Active Bridge converter, the function of one bridge leg of the conventional system is replaced by the zero-sequence voltage occurring at the star point of the drive motor. For the second concept, the transformer is directly integrated into the machine, i.e. a secondary winding is implemented for each phase. As these secondary windings are connected in series, the total voltage is equal to the zero-sequence voltage. The first concept already has been tested successfully; the measurements agree well with the simulations and the analytical model. Future challenges are the experimental analysis of concept 2 and the modeling of the high frequency losses and of the effects originating e.g. from partial saturation of the magnetic path of the electrical machine. 34
Starting date: November 2005 Funding: ETH/Industry
Integration of the isolated auxiliary DC-DC converter into the inverter and drive system (concept 2).
Simulation results for a 50 kW drive system with integrated 1kW auxiliary DC-DC converter based on concept 2. Operating parameters: drive DC link voltage vin=400 V, output voltage vout=14 V, total turns ratio 20:1.
Klaus Raggl Starting date: August 2005 Funding: KTI/Industry
Magnetically levitated pump with fully integrated 300 W power electronics. At a maximum rotation speed of 14 000 rpm a hydraulic pressure of 3 bar at a hydraulic flow of 5 l/min can be achieved.
Power electronics PCB for a fully integrated 300 W magnetically levitated pump system. The power MOSFETs are placed in a circle on the outside to ensure a thermal connection to the pump housing. The control unit is placed in the center of the PCB.
Integration and optimization for magnetically levitated machines
Bearingless motors offer great system benefits such as ultra-high purity due to their contactless levitation and an extremely compact setup, which is why they are the preferred pump solution. The trends in clean room technology suggest that the clean room floor space will have to be reduced by 50 % within the next 3 years. At the same time, the produced hydraulic pressure will have to double in order to compensate for the pressure losses of improved filter technologies, which are required for future high purity applications. Motivated by these trends, this research is focused on developing a new generation of integrated bearingless motors, incorporating the entire power electronics, sensors and motor into the pump housing. This will result in a significant step towards higher compactness and hydraulic pressure. Based on electrical, mechanical, thermal, and hydraulic models of the integrated pump system an overall optimization has been carried out and a first prototype with a total volume reduction of about 40 % and a hydraulic pressure increase of 45 % has been realized.
Frank Schafmeister Starting date: November 2001 Funding: ETH/Industry
A 1.5 kVA, three-phase, 400 V Sparse Matrix Converter constructed with SiC JFET cascode switches. The EMI filter is integrated into the heatsink. The switching frequency is 100 kHz.
Circuit schematic of the Sparse Matrix Converter showing the separate input rectifier and output inverter stages. A total of 15 switches are used compared to 18 switches required for a conventional matrix converter.
Sparse Matrix Converters
Sparse matrix converters (SMC) are reducedswitch-count indirect AC-AC converters. By using an indirect matrix converter (IMC) topology, the converter can be separated into an input rectifier stage and an output inverter stage. Switching losses in the rectifier stage can be eliminated by applying a modulation strategy where the output current free-wheels in the inverter stage and the rectifier stage is switched under zero current conditions. This research has derived, investigated and implemented new advanced modulation techniques for the IMC where the overall converter losses and common mode noise are minimized for certain operating points and/or applications. One example is the Low Output Voltage modulation method, where the rectifier is switched between the second and third highest input voltages rather than the highest voltages. Thus, the effective DC voltage applied to the inverter stage is reduced as are the inverter’s switching losses. Other extended modulation techniques allow an expanded reactive power control range and/or a coupling of the converter input and output reactive power generation to be achieved. The traditional back-to-back converter and the SMC have been compared analytically, with the SMC showing an improvement both in power density and efficiency.
35
Thomas Schneeberger Novel integrated bearingless hollow-shaft drive
Starting date: January 2004
Funding: KTI/Industry
The reproducibility of many industrial processes, especially in biotechnology applications and in the semiconductor industry, can be improved by the use of hermetically sealed process chambers. The design of existing process chambers relies on a gas-tight feed through of the rotating shaft in the process chamber wall. This causes a bulky design and the generation of damaging particles inside the chamber. Our new bearingless hollowshaft drive enables contactless levitation and rotation through the walls of the chamber. Due to the entire integration of the drive and the magnetic bearing, the over-all size of the motor is significantly smaller than any design with the magnetic bearings separated from the drive. All the elements necessary for the drive and bearings are placed outside the chamber on the motor stator. A first prototype of the outlined hollow-shaft drive with a rotor diameter of more than 300mm has been realized and successfully tested. The remaining challenge is to obtain a high running smoothness with large air gaps. This will be achieved using a fine tuned position sensing system and a special software-based unbalance compensation algorithm.
Detailed view of the experimental set-up with drive and bearing coils and the sensors for position and angle measuring.
Caracteristic waveforms for rotor deceleration from 800 rpm to zero. : rotor angle modulo 360 ° (Ch1: 217 °/ div), n: rotor speed (Ch2: 288 rpm/div), IA: current in drive phase A (Ch4: 10 A/div), time base: 40 ms/div.
Leonardo Serpa Current control techniques for multilevel grid connected inverters
The economic and environmental impacts of fossil fuels have forced governments and society to investigate sustainable solutions. Consequently, interest in the green and clean benefits provided by renewable energy sources has significantly increased, bringing together with it the necessity of efficient grid connected systems. Although these renewable sources can vary from few hundreds of watts in domestic photovoltaic applications, to the megawatts range in wind power plants, they all demand a similar dedicated power flow regulation between the energy source and the utility network. The main objective of this work is to develop new power control strategies that meet the voltage and power quality requirements of the utility grid when interfaced by an LCL filter. Two control techniques have been developed, one based on direct power control with virtual flux mains estimation and the other with decoupled hysteresis control. The power control methods have been experimentally verified on a conventional three-phase two-level inverter, an industry standard three-level Neutral-Point Clamped inverter and the five-level Active Neutral-Point Clamped inverter.
36
Starting date: March 2004
Funding: Industry
Three-phase, five-level, flying capacitor active neutral point clamped DC-AC converter with DSP control.
Near instantaneous transient response capability of the direct power flow controller based on virtual flux mains estimation for a three-phase, two-level DC-AC inverter with actively damped LCL filter.
Thiago Soeiro Starting date: October 2007 Funding: Industry
I 1 (t)
I L 1 (t)
I 2(t)
I L 2(t)
Three -Phase Diode Bridge
Resonant Tank and Transformer
Full-Bridge Inverter
Output Rectifier
+
v0
Mains
I 3(t)
-
I L 3(t)
ESP
I F1 (t)
Three-Phase PWM REctifier
I F2(t)
ESP power supply in combination with a shunt active filter for sinusoidal shaping of the currents drawn from the three-phase mains.
+ Cf
I F3(t)
-
Voltage Sensor
Drivers
V*C C CONTROL
ESP basic waveforms: (a) ESP output voltage (15 kV/div); (b) three-phase mains currents (100 A/div); (c) ESP power supply input currents (100 A/div); (d) shunt active filter input currents (100A/div).
High-voltage power supplies for electrostatic precipitation
With the increasing concern about environmental pollution, the reduction of particle emissions through the use of Electrostatic Precipitators (ESPs) is a highly important issue for coal fired power plants. Each of the multiple sections of a modern ESP has its own power supply, with a typical output power of 10–100 kW and an output voltage of 50 – 100 kVDC. In future, these power supplies will be operated more and more in pulsed mode and close to the flashover limit in order to increase collection efficiency. However, this results in frequent output short circuits causing severe distortions of the line currents. In this research pro-ject the overall influence of the multiple power supplies of an ESP on the mains current will be investigated and new control concepts for minimizing the effects on the mains without impairing collection efficiency will be derived. Furthermore, novel power supply converter topologies improving the power supply efficiency and control dynamics will be investigated. Since the availability of the ESP is highly critical, the effect of the pulsed operation on the life time of the ESP power supply semiconductor modules will also be analyzed in detail.
Stefan Waffler Starting date: December 2006 Funding: ETH/Industry
Digitally controlled bidirectional buck+boost DC/DC converter module; output power: 12 kW peak, V1= 150 V ... 450 V, V2= 150 V… 450 V, switching frequency fP=100 kHz; power density: 17.5 kW/dm3.
Measured overall converter efficiency in dependency on output power and voltage transfer ratio.
99
Overall Efficiency [%]
98
Bi-directional DC-DC converter for fuel cell hybrid vehicles
Fuel Cell Hybrid Vehicles (FCHVs) are one approach to increase the energy efficiency and reduce carbon dioxide emissions of standard vehicles. In FCHVs the electric drive-train motor is supplied by an inverter connected to a fuel cell. In addition, high-voltage batteries are employed to provide better cold start characteristics and the option to recuperate braking energy. This research investigates bi-directional DC/DC converters that interface the high-voltage battery and the fuel cell. Requirements are a nominal power of typically 40 kW and a topology that allows a buck+boost operation since the input and output voltages vary depending on the state of charge of the battery. To overcome efficiency and EMI drawbacks of stateof-the-art hard-switched converters, soft-switching techniques and resonant topologies have been analyzed. A novel zero-voltage-switching, multiphase converter system has been built that has a very high efficiency and highly compact design.
97
V1
V2
400V Y 200V 350V Y 250V 300V Y 300V 225V Y 375V
96
95 0
2000
4000
6000
8000
10000
Converter Output Power P2 [W]
37
Wanfeng Yan Lifetime modeling and reliability estimation of Power Electronic Building Blocks
In order to guarantee a certain life-time for power electronic systems there is a strong desire from the industry to estimate the reliability of converter systems or converter subsystems such as power modules. A significant amount of failures of electronics is caused by overheating or temperature-cycling. In this research, existing reliability and lifetime models for power electronic systems and subsystems will be evaluated, modified and extended. The derived models will be tested against experimental data from accelerated cycling tests. Furthermore, a software tool that enables reliability and life time estimations based on material data, geometric descriptions and mission profiles will be developed. The software tool finally will be integrated into a multi-disciplinary software platform for virtual prototyping in power electronics.
Starting date: October 2007 Funding: ETH/Industry
Mission profile ∆T(t) Rainflow algorithm g(∆T) : extraction of thermal excursions (fatigue cycles) inside one mission profile
g(∆T) (analytical or numerical form )
∆Tmax
Q=
∫
∆Tmin
g(∆T) d(∆T) Nf(∆T)
∆T
Q=
1 maxg(∆T) d(∆T) a ∆T∫ ∆T-n min
Accelerated tests (power cycle experiment ) log-log plot: Nf (∆T) Coffine Manson law -n Nf (∆T) = a(∆T)
Extracted parameters a and n
MTTF =
1 Q
Reliability modeling based on a mission profile defining temperature swings over time, and data from accelerated tests allowing to parameterize the CoffinManson equation. The Rainflow algorithm gives the probability density function g (∆T). Model outputs are the damage Q and/or the mean time to failure MTTF.
Chuanhong Zhao Isolated bidirectional three-port DC-DC converter
In order to meet the increasing power demand of auxiliary equipment, a 42 V bus is introduced in hybrid electric vehicles and will eventually replace the existing 14 V bus in future. During the transition period, a triple-voltage system, i.e. 14 V/42 V for the auxiliaries and 200 V ... 650 V for the propulsion system could be employed. It is therefore desirable to have an integrated isolated power electronics converter capable of directly interfacing the voltage buses instead of two individual DC-DC converters. This will result in higher efficiency, lower weight and reduced volume. A three-port converter, where the three ports are coupled via a three-winding transformer and their corresponding full-bridge cells, is proposed and analyzed in this research project. The system allows a fully bidirectional power flow between all ports. For power flow control the phase-shifts of the individual full-bridge cells and the duty cycles are utilized to achieve minimum overall losses. The power of the ports can be controlled independently by employing a decoupling controller. Furthermore, excellent dynamic response is guaranteed by designing the control based on a precise small signal model. Moreover, the converter can be started from one and/or two ports without any additional circuit. A prototype has been built and the performance verified experimentally.
38
Starting date: May 2003
Funding: ETH
Isolated bidirectional DC-DC converter, where the high frequency coupling of three four-quadrant full-bridge cells is realized via a single transformer.
Overall system losses in dependency on the control variables ø2 and ø3 (phase shift of converters 2 and 3 against converter 1); the optimum operating point within the admissible operating range is defined by minimum total power losses.
Christof Zwyssig Starting date: November 2004 Funding: ETH
Power and control electronics, machine stator and shaft of the 100 W, 500 000 rpm drive system; together with a completed 100 W, 1 000 000 rpm machine.
Rotational speed (rpm)
Application areas and trends for cm-scale ultra high speed drives and Power MEMS; future research will focus on the intersection of mesoscale systems and microsystems and speeds beyond 1 000 000 rpm.
ETH Zurich ‹Mega-n-Drives›
1 000 000 rpm
106
research
Power MEMS development trend micro turbines and compressors
105 MEMS
spindle drives turbomachinery scaling/limit mesoscale systems
104
10-4
10-2
100
102 Power (W)
industrial gas turbines
104
106
Mega-Speed Drives
The development of new ultra-compact electrical Mega-Speed Drive systems is called for in emerging applications such as generators/starters for micro gas turbines, fuel-cell air compressors, dental drills, and machine spindles. For rotational speeds up to 1 million rpm and beyond, and power levels up to several kW, innovative solutions for the electrical machine, the power electronics and sensorless speed controller have to be created. Our group is concentrating its research on the ultra-high speed range above 500 000 rpm. The focus of this research is the development of new concepts for the electrical machines, inverter topologies and control methods. The goal is to produce the best combination of individual parts in order to realize a Mega-Speed system with the highest efficiency and power density. An integrated design and optimization method for the machine has been established, voltage and current source inverter topologies compared and a novel sensorless control method developed. The research has been verified with several hardware prototypes, including a world record speed of > 1 000 000 rpm for a 100 W electrical machine.
108
electrical drives trends PES main trend
39
Appendix II + III Completed PhD Theses 2001 – 2007 Publications and Patents 2001 – 2007
Appendix II
Appendix III
Completed PhD Theses 2001 – 2007
Publications and Patents 2001 – 2007
[18] L. Dalessandro; Optimal Modulation and Wideband Current Sensing for Three-Level PWM Rectifiers. 2007 [17] L. Serpa; Current Control Strategies for Multilevel Grid Connected Inverters. 2007 [16] F. Schafmeister; Indirekte Sparse-Matrix Konverter. 2007 [15] S. Burger; Magnetgelagertes Pumpsystem für hohe Betriebstemperaturen. 2006 [14] M. Häflinger; Beiträge zur Durchflussregelung von hochreinen und aggressiven Flüssigkeiten. 2006 [13] J. Biela; Optimierung des elektromagnetisch integrierten serienparallel Resonanzkonverters mit eingeprägtem Ausgangsstrom. 2005 [12] F. Cavalcante; High Output Voltage Series-Parallel Resonant DC-DC Converter for Medical X-Ray Imaging Applications. 2005 [11] R. Greul; Modulare Dreiphasen Pulsgleichrichtersysteme. 2005 [10] G. Laimer; Ultrakompaktes 10kW/500kHz Dreiphasen-Gleichrichtermodul. 2005 [9] M. Baumann; Theoretische und experimentelle Untersuchung eines Dreiphasen-Pulsgleichrichtersystems mit Dreischalter Tiefsetzstellereingangsstufe und integrierter Hochsetzstellerausgangsstufe mit sinusförmiger Eingangsstromführung. 2005 [8] S. Huwyler; Lagerloses Rotationsviskosimeter für die Halbleiterindustrie. 2005 [7] T. Nussbaumer; Netzrückwirkungsarmes Dreiphasen-Pulsgleichrichtersystem; 2004 [6] D. Schrag; Durchflussmesser für hochreine und aggressive Flüssigkeiten. 2004 [5] P. Zwimpfer; Modulationsverfahren für einen zweistufigen Matrixkonverter zur Speisung von Drehstromantrieben. 2002 [4] O. Garcia; DC/DC-Wandler für die Leistungsverteilung in einem Elektrofahrzeug mit Brennstoffzellen und Superkondensatoren. 2002 [3] J. Riatsch; Modulintegriertes Umrichtersystem für die Netzanbindung einer einzelnen grossflächigen Niederspannungs-Solarzelle. 2001 [2] R. Schmidt; Systemverhalten einer zweistufigen KonverterAnordnung für den modularen Fotovoltaik-Anlagebau. 2001 [1] D. Zuber; Mittelfrequente resonante DC/DC-Wandler für Traktionsanwendungen. 2001
Professional Journals – in Preparation [45] Round, S. D., Karutz, P., Heldwein, M. L., Kolar, J. W.: Towards a 30 kW/liter, Three-Phase Unity Power Factor Rectifier. Accepted for publication in IEE Japan Transactions, vol. 128-D, No.4, April 2008 [44] Kolar, J. W., Heldwein, M. L., Drofenik, U., Biela, J., Ertl, H., Friedli, T., Round, S. D.: PWM Converter Power Density Barriers. Accepted for publication in IEE Japan Transactions, vol. 128-D, No.4, April 2008 [43] Dalessandro, L., Round, S. D., Drofenik, U., and Kolar, J. W.: Discontinuous Space-Vector Modulation for Three-Level PWM Rectifiers. Accepted for publication in the IEEE Transactions on Power Electronics [42] Nussbaumer, T., Gong, G., Heldwein, M. L., and Kolar, J. W.: Modeling and Robust Control of a Three-Phase Buck+Boost PWM Rectifier (VRX-4). Accepted for publication in the IEEE Transactions on Industry Applications [41] Biela, J., and Kolar, J. W.: Using Transformer Parasitics for Resonant Converters - A Review of the Calculation of the Stray Capacitance of Transformers. Accepted for publication in the IEEE Transactions on Industry Applications [40] Mino, K., Nishida, Y., and Kolar, J. W.: Novel Hybrid 12-Pulse LineInterphase-Transformer Boost-Type Rectifier with Controlled Output Voltage and Sinusoidal Utility Currents. Accepted for publication in the IEE Japan Transactions [39] Biela, J., Bortis, D., and Kolar, J. W.: Modeling of Pulse Transformers with Parallel- and Non-Parallel-Plate Windings for Power Modulators. Accepted for publication in the IEEE Transaction on Dielectrics and Electrical Insulation [38] Zwyssig, C., Round, S. D., and Kolar, J. W.: An Ultra-High-Speed, Low Power Electrical Drive System. Accepted for publication in the IEEE Transactions on Industrial Electronics [37] Nussbaumer, T., Heldwein, M. L., Gong, G., Round, S. D., and Kolar, J. W.: Comparison of Prediction Techniques to Compensate Time Delays Caused by Digital Control of a Three-Phase Buck-Type PWM Rectifier System. Accepted for publication in the IEEE Transactions on Industrial Electronics [36] Nussbaumer, T., and Kolar, J. W.: Comparison of Three-Phase Wide Output Voltage Range PWM Rectifiers. Accepted for publication in the IEEE Transactions on Industrial Electronics [35] Baumann, M., and Kolar, J. W.: A Novel Control Concept for Reliable Operation of a Three-Phase Three-Switch Buck-Type Unity Power Factor Rectifier with Integrated Boost Output Stage under Heavily Unbalanced Mains Condition. Accepted for publication in the IEEE Transactions on Industrial Electronics [34] Miniböck, J., Stögerer, F., and Kolar, J. W.: A Novel Concept for Mains Voltage Proportional Input Current Shaping of a VIENNA Rectifier Eliminating Controller Multipliers. Accepted for publication in the IEEE Transactions on Industrial Electronics [33] Ertl, H., Kolar, J. W., and Zach, F. C.: A Constant Output Current Three-Phase Diode Bridge Employing a Novel «Electronic Smoothing Inductor». Accepted for publication in the IEEE Transactions on Industrial Electronics
42
Professional Journals [32] Dalessandro, L., Karrer, N., and Kolar, J. W.: High-Performance Planar Isolated Current Sensor for Power Electronics Applications. IEEE Transactions on Power Electronics, vol. 22, no. 5, pp. 1682-1692, Sept. 2007 [31] Dalessandro, L., Cavalcante, F., and Kolar, J. W.: Self-Capacitance of High-Voltage Transformers. IEEE Transactions on Power Electronics, vol. 22, no. 5, pp. 2081-2092, Sept. 2007 [30] Greul, R., Round, S., and Kolar, J. W.: Analysis and Control of a Three-Phase, Unity Power Factor Y-Rectifier. IEEE Transactions on Power Electronics, vol.22, no.5, pp.1900-1911, Sept. 2007 [29] Serpa, L. A., Round, S., and Kolar, J. W.: A Virtual-Flux Decoupling Hysteresis Current Controller for Mains Connected Inverter Systems. IEEE Transactions on Power Electronics, vol.22, no.5, pp.1766-1777, Sept. 2007 [28] Kolar, J. W., Schafmeister, F., Round, S. D., and Ertl, H.: Novel Three-Phase AC-AC Sparse Matrix Converters. IEEE Transactions on Power Electronics, vol.22, no.5, pp.1649-1661, Sept. 2007 [27] Greul, R., Round, S., and Kolar, J. W.: The Delta-Rectifier: Analysis, Control and Operation. IEEE Transactions on Power Electronics, vol. 21, issue 6, Nov. 2006, pp. 1637-1648. [26] Nussbaumer, T., Baumann, M., and Kolar, J. W.: Comprehensive Design of a Three-Phase Three-Switch Buck-Type PWM Rectifier. IEEE Transactions on Power Electronics, Vol. 22, Issue 2, pp. 551-562, March 2007 [25] Nussbaumer, T., Heldwein, M. L., and Kolar, J. W.: Differential Mode Input Filter Design for a Three-Phase Buck-Type PWM Rectifier Based on Modeling of the EMC Test Receiver. IEEE Transactions on Industrial Electronics, Vol. 53, Issue 5, pp. 1649-1661, Oct. 2006 [24] Schönberger, J., Duke, R., and Round, S.: A Distributed Control Strategy for a Hybrid Renewable Nanogrid. IEEE Transactions on Industrial Electronics, vol. 53, no. 5, pp. 1453-1460, October 2006 [23] Zwyssig, C., and Kolar, J. W.: Design Considerations and Experimental Results of a 100 W, 500 000 rpm Electrical Generator. Journal of Micromechanics and Microengineering. Issue 9, pp. 297-302, Sept. 2006 [22] Nussbaumer, T., and Kolar, J. W.: Improving Mains Current Quality for Three-Phase Three-Switch Buck-Type PWM Rectifiers. IEEE Transactions on Power Electronics, Vol. 21, No. 4, pp. 967-973, July 2006 [21] Drofenik, U., and Kolar, J. W.: A Thermal Model of a Forced-Cooled Heat Sink for Transient Temperature Calculations Employing a Circuit Simulator. IEE Japan Transactions , Volume 126-D, Number 7, pp. 841851, July 2006 [20] Biela, J., and Kolar, J. W.: Analytic Model inclusive Transformer for Resonant Converters based on Extended Fundamental Frequency Analysis for Resonant Converter-Design and Optimization. IEE Japan, Volume 126-D, Number 5, pp. 568-577, May 2006 [19] Round, S., Schafmeister, F., Heldwein, M., Pereira, E., Serpa, L., and Kolar, J. W.: Comparison of Performance and Realization Effort of a Very Sparse Matrix Converter to a Voltage DC Link PWM Inverter with Active Front End. IEE Japan, Volume 126-D, Number 5, pp. 578588, May 2006
[18] Nussbaumer, T., and Kolar, J. W.: Improving Mains Current Quality for Three-Phase Three-Switch Buck-Type PWM Rectifiers. IEEE Transactions on Power Electronics, Vol. 21, No. 4, pp. 967-973, July 2006 [17] Drofenik, U., and Kolar, J. W.: A Thermal Model of a Forced-Cooled Heat Sink for Transient Temperature Calculations Employing a Circuit Simulator. IEE Japan Transactions of Japan, Volume 126-D, Number 7, pp. 841-851, July 2006 [16] Kolar, J. W., and Round, S.: Analytical Calculation of the RMS Current Stress on the DC Link Capacitor of Voltage PWM Converter Systems. IEE Proceedings Electric Power Applications, Vol. 153, Issue 4, pp. 535-543, July 2006 [15] Dalessandro, L., Odendaal, W. G., and Kolar, J. W.: HF Characterization and Non-Linear Modeling of a Gapped Toroidal Magnetic Structure. IEEE Transactions on Power Electronics, Vol. 21, no 5, pp. 1167-1175, Sept. 2006 [14] Kolar, J. W., Miniböck, J., and Nussbaumer, T.: Three-Phase PWM Power Conversion - The Route to Ultra High Power Density and Efficiency. Power Electronics (Xian Power Electronics – Research Institute/MMI - Power Electronics Society/CES), vol. 39, no. 6, pp. 2-9, Dec. 2005 [13] Dalessandro, L., and Rosato, D.: Finite Element Analysis of the Frequency Response of a Metallic Cantilever Coupled with a Piezoelectric Transducer. IEEE Transactions on Instrumentation and Measurement, vol. 54, no. 5, pp. 1881-1890, Oct. 2005. [12] Vezzini, A., Kolar, J. W., and Goette, J.: Massen in Bewegung setzen. Bulletin SEV/VSE 05/15, Seite 18-24, Juli 2005. [11] Schönberger, J., Duke, R., and Round, S.: Decentralised Source Scheduling in a Model Nanogrid using DC Bus Signalling. Australian Journal Electrical & Electronics Engineering, Engineers Australia, vol. 2, no. 3, pp. 183-190, 2005 [10] Hsieh, M-K., Round, S., and Duke, R.: An Investigation of Battery Voltage Equalisation Topologies for an Electric Vehicle. Australian Journal of Electrical & Electronics Engineering, Engineers Australia, vol. 2, no. 3, pp. 247-254, 2005 [9] Mino, K., Gong, G., and Kolar, J. W.: Novel Hybrid 12-Pulse Boost-Type Rectifier with Controlled Output Voltage. IEEE Transactions on Aerospace and Electronic Systems, vol. 41, no. 3, pp. 1008-1018, July 2005 [8] Gong, G., Heldwein, M. L., Drofenik, U., Mino, K., and Kolar, J. W.: Comparative Evaluation of Three-Phase High-Power-Factor AC-DC Coverter Concepts for Application in Future More Electric Aircraft. IEEE Transactions on Industrial Electronics, vol. 52, no. 3, pp. 727-737, June 2005 [7] Ide, P., Schafmeister, F., Fröhleke, N., and Grotstollen, H.: Enhanced Control Scheme for Three-Phase Three-Level Rectifiers at Partial Load. IEEE Transactions on Industrial Electronics, vol. 52, no. 3, pp. 719726, June 2005 [6] Drofenik, U., Laimer, G., and Kolar, J. W.: Pump Characteristic Based Optimization of a Direct Water Cooling System for a 10 kW/500 kHz Vienna Rectifier. IEEE Transactions on Power Electronics, vol. 20, no. 3, pp. 704-714, May 2005
43
[5] [4]
[3]
[2]
[1]
Bauer, P., and Kolar, J. W.: Teaching Power Electronics in the 21st Century. EPE Journal, Vol.13, No.4, pp. 43-50, November 2003 Schafmeister, F., Baumann, M., and Kolar, J. W.: Analytically Closed Calculation of the Conduction Losses of Three-Phase AC-AC Sparse Matrix Converters. EPE Journal, Vol.13, No.1, pp. 5-14, February 2003 Drofenik, U., and Kolar, J. W.: A Novel Interactive Power Electronics Seminar (iPES) Developed at the Swiss Federal Institute of Technology (ETH) Zurich. Journal of Power Electronics (The Korean Institute of Power Electronics), Vol.2, No.4, pp. 250-257, October 2002 Ertl, H., Kolar, J. W., and Zach, F. C.: A Novel Multicell DC-AC Converter for Applications in Renewable Energy Systems. IEEE Transactions on Industrial Electronics, Vol. 49. No. 5, pp. 1048-1053, 2002 Ertl, H., Kolar, J. W., and Zach, F. C.: Analysis of a Multilevel Multicell Switch-Mode Power Amplifier Employing the ‚Flying-Battery‘ Concept. IEEE Transactions on Industrial Electronics, Vol. 49, No. 4, pp. 816-823, 2002
Patents in Preparation [43] Biela, J., Plesko, H., Kolar, J. W.; Integration einer DC-DC Konverterfunktion in ein pulsumrichtergespeistes Antriebssystem mit Dreieckschaltung der Motorwicklungen. [42] Zwyssig, Ch., Kolar J. W.; Integration der Vorschaltinduktivitäten in den Magnetkreis permanentmagneterregter Synchronmaschine mit geringer Induktivität der Statorwicklung. [41] Krähenbühl, D., Zwyssig, Ch., Kolar, J. W.; Künstlicher Muskel mit integriertem hochkompaktem Turbokompressor. [40] Krähenbühl, D., Zwyssig, Ch., Kolar, J. W; Vorrichtung zur Gewinnung elektrischer Leistung aus komprimierten Gasströmen. [39] Kolar J., Round, S., Schönberger, J.; Eingangsstromregelung hybrider 12-puls Gleichrichtersysteme mit raumzeigerbasierter Pulsbreitenmodulation der Eingangsspannung der netzseitigen Saugdrossel. [38] Schafmeister, F., Kolar, J. W.; Verfahren zum spannungslosen Schalten der Ausgangsstufe eines dreiphasigen Ultra-Sparse Matrix Converter. [37] Friedli, T., Schafmeister, F., Kolar, J. W.; Verfahren zur Maximierung der Regeldynamik bei dreiphasigen unidirektionalen Matrix-Konvertersystemen. [36] Kolar, J. W., Miniböck, J.; Vorrichtung zur pulsförmigen Speisung von Piezo-Leistungsaktoren. [35] Heldwein, M., Kolar, J. W.; Elimination der parasitären Wicklungskapazitäten dreiphasiger Common-Mode-Induktivitäten [34] Kolar, J. W., Drofenik, U.; Vorrichtung zur Kühlung von Leistungselektronik mit fraktaler Finnenstruktur.
44
Patents [33] Bortis, D., Waffler, S., Biela, J., Kolar, J. W.: Verfahren zur Konstantstromspeisung von Pulsed Power Systemen bei hoher pulsfrequenter Schwankung der Eingangskondensatorspannung; June 22, 2007 [32] Bortis, D., Biela, J., Kolar, J. W.: Vorrichtung und Verfahren zur verlustarmen negativen Vormagnetisierung von HochleistungsPulstransformatoren; June 21, 2007 [31] Kolar, J. W.: Vorrichtung zur Regelung der Phasenzwischenkreisspannungen einer Sternschaltung einphasiger Pulsgleichrichtersysteme in Analogie zu Dreiphasen-Dreipunkt-Pulsgleichrichtersystemen; Nov. 23, 2006 [30] Friedli, T., Kolar, J. W.: Verfahren zur Dreipunktmodulation eines quasi-direkten Dreiphasen-AC/AC-Pulsumrichter; Nov. 7, 2006 [29] Krismer, F., Kolar, J. W.: Verfahren zur schaltverlustminimalen Steuerung eines bidirektionalen nicht potentialgetrennten Gleichspannungswandlers mit überlappendem Ein- und Ausgangsspannungsbereich; Nov. 6, 2006 [28] Serpa, L., Ponnaluri, S.: Active Damping Method for Direct PowerControlled Voltage Source Inverters with LCL Filter; Sept. 15, 2006 [27] Plesko, H., Biela, J., Kolar, J. W.: Drehstromantriebssystem mit hochfrequent potentialgetrennter bidirektionalen Kopplung der Versorgungsspannungen, July 27, 2006 [26] Biela, J., Plesko, H., Kolar, J. W.: Drehstromantriebssystem mit motorintegriertem Hochfrequenztrafo zur bidirektionaler Kopplung der Versorgungsspannungen; July 27, 2006 [25] Ertl, H., Kolar, J. W.: Vorrichtung zur Bestimmung des Verlustwiderstandes von Elektrolytkondensatoren; May 9, 2006 [24] Miniböck, J., Kolar, J. W.: Vorrichtung zur Messung gleichanteilbehafteter Wechselströme mittels eines einfachen Wechselstromwandlers; Feb. 28, 2006 [23] Kolar, J. W.: Vorrichtung zur Minimierung der Leitverluste integrierter Dreiphasen-Tief-Hochsetzsteller-Pulsgleichrichtersysteme; Feb. 16, 2006 [22] Kolar, J. W.: Vorrichtung zur Regelung der Teilausgangsspannungen eines Dreipunkt-Hochsetzstellers; Jan. 20, 2006 [21] Serpa, L., Round, S., Kolar, J. W.: Virtual-Flux Decoupling Hysteresis Control for Mains Connected Inverter Systems; Nov. 21, 2005 [20] Biela, J., Kolar, J. W.: Vorrichtung zur aktiven Unterdrückung leitungsgebundener Gleichtakt- und Gegentaktstöraussendung leistungselektronischer Konverter; Sept. 14, 2005 [19] Kolar, J. W, Ertl, H.: Multizellen Hybrid-Leistungsverstärker zur Realisierung einer verlustarmen Testspannungsquelle geringen Innenwiderstandes und hoher Bandbreite; May 10, 2005 [18] Round, S., Kolar, J. W.: Vorrichtung zur Koordination der Taktung und Sicherstellung konstanter Schaltfrequenz der Brückenzweige von Drehstrom-Pulsgleichrichtersystemen mit Toleranzbandregelung der Eingangsströme; March 4, 2005 [17] Mino, K., Nishida, Y., Kolar, J. W.: Hybride Zwölfpulsgleichrichtung mit geregelter modulierter Ausgangsspannung und rein sinusförmiger Stromaufnahme; Jan. 31, 2005 [16] Ponnaluri, S., Serpa, L.: Verfahren zum Betrieb einer Umrichterschaltung sowie Vorrichtung zur Durchführung des Verfahrens; Jan. 25, 2005
[15] Kolar, J. W.: Vorrichtung zur Entkopplung der Phasen-Toleranzbandregelungen dreiphasiger Dreipunkt-Pulsgleichrichtersysteme bei voller Nutzung des linearen Aussteuerbereiches und aktiver Symmetrierung der Ausgangsteilspannungen; Jan. 14, 2005 [14] Kolar, J. W, Greul, R.: Vorrichtung zur Regelung der Zwischenkreisspannungen einer Sternschaltung einphasiger Stromversorgungsmodule mit Pulsgleichrichtereingangsstufe und offenem Sternpunkt; June 21, 2004 [13] Schafmeister, F., Kolar, J. W.: Verfahren zur Nutzung des ausgangsseitigen Blindstromes eines indirekten Dreiphasen-Matrixkonverters zur Erzeugung von Eingangsblindstrom; June 21, 2004 [12] Biela, J., Kolar, J. W.: Verlustarmer Hochfrequenztransformator mit ausgeprägter Streuung und geringer elektromagnetischer Störaussendung für den Einsatz in Serien-Parallel-Resonanzkonvertern; June 7, 2004 [11] Nussbaumer, T., Kolar, J. W.: Modulationsverfahren zur Minimierung der Netzstromverzerrungen dreiphasiger Dreischalter-TiefsetzstellerPulsgleichrichtersysteme; March 30, 2004 [10] Kolar, J. W., Miniböck, J.: Vorrichtung zur pulsförmigen bipolaren Ansteuerung eines Piezo-Aktors hoher Leistung; March 25, 2004 [9] Kolar, J. W., Ertl, H.: Vorrichtung zur Trennung der Funkstörspannungen dreiphasiger Stromrichtersysteme in eine Gleichtakt- und eine Gegentaktkomponente; March 16, 2004 [8] Kolar, J. W., Miniböck, J.: Vorrichtung hoher Gleichtaktstörfestigkeit zur Ansteuerung abschaltbarer Leistungshalbleiter; April 25, 2003 [7] Kolar, J. W., Gong, G.: Vorrichtung zur Potentialtrennung und ausgangssignalabhängigen Führung der Versorgungsspannungen eines Linear-Leistungsverstärkers; April 1, 2003 [6] Kolar, J. W., Schafmeister, F.: Verfahren zur Minimierung der Schaltverluste eines quasi-direkten Dreiphasen-AC/AC-Pulsumrichters bei geringer Amplitude der Ausgangsspannungsgrundschwingung; Feb. 5, 2003 [5] Herold, S., Kolar, J. W.: Modulationsverfahren zur Minimierung und gleichmässigen Verteilung von Schaltverlusten in quasi-direkten Dreiphasen-AC/AC-Pulsumrichtern; Jan. 24, 2003 [4] Kolar, J. W., Baumann, M.: Vorrichtung zur Sicherstellung sinusförmiger Stromaufnahme eines dreiphasigen Tief-HochsetzstellerPulsgleichrichtersystems bei unsymmetrischer Netzspannung und Phasenausfall; Jan. 2, 2003 [3] Kolar, J. W., Baumann, M.: Verfahren zur Unterdrückung von Kreisströmen zwischen parallelgeschalteten Dreiphasenpulsgleichrichtersystemen mit eingeprägtem Ausgangsstrom; June 3, 2002 [2] Kolar, J. W.: Dreiphasiger Hybrid-Wechselspannungs-Wechselspannungs-Direktumrichter minimaler Komplexität und hoher Kommutierungssicherheit; Aug. 31, 2001 [1] Kolar, J. W., Ertl, H.: Vorrichtung zur quasi-direkten pulsbreitengesteuerten Energieumformung zwischen Dreiphasensystemen; July 27, 2001
Conference Papers [153] Kolar, J. W., Zwyssig, C., and Round, S. D.: Beyond 1 000 000 rpm – Review on Mega-Speed Drive Systems. Proceedings of the 9th Brazilian Power Electronics Conference (COBEP‘07), Blumenau, Brazil, Sept. 30 – Oct. 4, CD-ROM ISBN 978-85-99195-02-4 (2007) [152] Heldwein, L. M., and Kolar, J. W.: Design of Minimum Volume EMC Input Filters for an Ultra Compact Three-Phase PWM Rectifier. Proceedings of the 9th Brazilian Power Electronics Conference (COBEP‘07), Blumenau, Brazil, Sept. 30 - Oct. 4, CD-ROM ISBN 978-85-99195-02-4 (2007) [151] Serpa, L. A., and Kolar, J. W.: Extended Virtual-Flux Decoupling Hysteresis Control for Mains Connected Three-Level NPC Inverter Systems. Proceedings of the 9th Brazilian Power Electronics Conference (COBEP‘07), Blumenau, Brazil, Sept. 30 – Oct. 4, CD-ROM ISBN 978-85-99195-02-4 (2007) [150] Biela, J., Drofenik, U., Krenn, F., Miniböck, J., and Kolar, J. W.: Novel Three-Phase Y-Rectifier Cyclic 2 out of 3 DC Output Voltage Balancing. Proceedings of the 29th International Telecommunications Energy Conference (INTELEC‘07), Rome, Italy, Sept. 30 – Oct. 4 (2007) [149] Biela, J., Badstübner, U., and Kolar, J. W.: Design of a 5 kW, 1 U, 10 kW/ltr. Resonant DC-DC Converter for Telecom Applications. Proceedings of the 29th International Telecommunications Energy Conference (INTELEC‘07), Rome, Italy, Sept. 30 – Oct. 4 (2007) [148] Drofenik, U., Cottet, D., Müsing, A., and Kolar, J. W.: Design Tools for Power Electronics: Trends and Innovations. Proceedings of the 2nd International Conference on Automotive Power Electronics (APE‘07), Paris, France, Sept. 26 – 27 (2007) [147] Luomi, J., Zwyssig, C., Looser, A., and Kolar, J. W.: Efficiency Optimization of a 100-W, 500 000-rpm Permanent-Magnet Machine Including Air Friction Losses. Conference Record of the 2007 IEEE Industry Applications Conference 42nd IAS Annual Meeting (IAS‘07), New Orleans (LA), USA, Sept. 23 – 27, CD-ROM ISBN 1-42441260-9 (2007). [146] Friedli, T., Round, S. D., and Kolar, J. W.: Modeling the Space Elevator – A Project Oriented Approach for Teaching Experimental Power Electronics. Proceedings of the 12th European Conference on Power Electronics and Applications (EPE‘07), Aalborg, Denmark, Sept. 2 – 5, CD-ROM, ISBN: 9789075815108 (2007). [145] Heldwein, M., and Kolar, J. W.: Extending Winding Capacitance Cancellation to Three-Phase EMC Input Filter Networks. Proceedings of the 2007 IEEE International Symposium on Electromagnetic Compatibility (EMC‘07), Honolulu (Hawaii), USA, July 8 – 13, (2007). [144] Biela, J., Bortis, D., and Kolar, J. W.: Reset Circuits with Energy Recovery for Solid State Modulators. Proceedings of the Pulsed Power and Plasma Science Conference, Albuquerque (NM), USA, June 17 – 22, (2007). [143] Bortis, D., Waffler, S., Biela, J., and Kolar, J. W.: 25kW 3-Phase Unity Power Factor Buck+Boost Rectifier with Wide Input and Output Range for Pulse Load Applications. Proceedings of the Pulsed Power and Plasma Science Conference, Albuquerque (NM), USA, June 17 – 22, (2007).
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[142] Bortis, D., Biela, J., and Kolar, J. W.: Active Gate Control for Current Balancing in Parallel Connected IGBT Modules in Solid State Modulators. Proceedings of the Pulsed Power and Plasma Science Conference, Albuquerque (NM), USA, June 17 - 22, (2007). [141] Friedli, T., Round, S. D., and Kolar, J. W.: A 100 kHz SiC Sparse Matrix Converter. Proceedings of the IEEE 38th Annual Power Electronics Specialists Conference, Orlando, USA, June 17 – 21, ISBN 1-4244-0655-2, pp. 2148-2154 (2007) [140] de Jager, K., Dalessandro, L., Hofsajer, I. W., and Odendaal, W. G.: Wave Analysis of Multilayer Absorptive Low-Pass Interconnects. Proceedings of the IEEE 38th Annual Power Electronics Specialists Conference, Orlando, USA, June 17 – 21, ISBN 1-4244-0655-2, pp. 2121-2127 (2007) [139] Drofenik, U., Cottet, D., Müsing, A, Meyer, J.-M., and Kolar, J. W.: Modelling the Thermal Coupling between Internal Power Semiconductor Dies of a Water-Cooled 3300V/1200A HiPak IGBT Module. Proceedings of the Conference for Power Electronics, Intelligent Motion, Power Quality (PCIM‘07), Nuremberg, Germany, May 22 – 24, CD-ROM (2007). [138] Bontemps, S., Calmels, A., Round, S. D., and Kolar, J. W.: Low Profile Power Module Combined with State of the Art MOSFET Switches and SiC Diodes allows High Frequency and Very Compact ThreePhase Sinusoidal Input Rectifiers. Proceedings of the Conference for Power Electronics, Intelligent Motion, Power Quality (PCIM‘07), Nuremberg, Germany, May 22 – 24, CD-ROM (2007). [137] Wiedemuth, P., Bontemps, S., and Miniböck, J.: 35 kW Active Rectifier with Integrated Power Modules. Proceedings of the Conference for Power Electronics, Intelligent Motion, Power Quality (PCIM‘07), Nuremberg, Germany, May 22 – 24, CD-ROM (2007). [136] Hartmann, M., and Ertl, J.: Design and Realization of a Multi-CellSwitch-Mode Power Amplifier Employing a Digital Poly-PhasePulse-Width-Modulator. Proceedings of the Conference for Power Electronics, Intelligent Motion, Power Quality (PCIM‘07), Nuremberg, Germany, May 22 – 24, CD-ROM (2007). [135] Nishida, Y., Okuma, Y., and Mino, K.: Practical Evaluation of Simple 12-Pulse Three-Phase-Bridge Diode Rectifier of Capacitor-Input-Type. Proceedings of the Conference for Power Electronics, Intelligent Motion, Power Quality (PCIM‘07), Nuremberg, Germany, May 22 – 24, CD-ROM (2007). [134] Drofenik, U., and Kolar, J. W.: Sub-Optimum Design of a Forced Air Cooled Heat Sink for Simple Manufacturing. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [133] Drofenik, U., Cottet, D., Müsing, A., Meyer, J.-M., and Kolar, J. W.: Computationally Efficient Integration of Complex Thermal Multi-Chip Power Module Models into Circuit Simulators. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [132] Bartholet, M. T., Nussbaumer, T., Krähenbühl, D., Zürcher, F., and Kolar, J. W.: Modulation Concepts for the Control of a Two-Phase Bearingless Slice Motor Utilizing Three-Phase Power Modules. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). 46
[131] Serpa, L. A., and Kolar, J. W.: Virtual-Flux Direct Power Control for Mains Connected Three-Level NPC Inverter Systems. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [130] Aggeler, D., Biela, J., Inoue, S., Akagi, H., and Kolar, J. W.: Bi-Directional Isolated DC-DC Converter for Next-Generation Power Distribution – Comparison of Converters using Si and SiC Devices. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [129] Biela, J., and Kolar, J. W.: Cooling Concepts for High Power Density Magnetic Devices. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 14244-0844-X, (2007). [128] Round, S. D., Karutz, P., Heldwein, M. L., and Kolar, J. W.: Towards a 30 kW/liter, Three-Phase Unity Power Factor Rectifier. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [127] Müsing, A., Heldwein, M. L., Friedli, T., and Kolar, J. W.: Steps Towards Prediction of Conducted Emission Levels of an RB-IGBT Indirect Matrix Converter. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [126] Nussbaumer, T., Raggl, K., Boesch, P., and Kolar, J. W.: Trends in Integration for Magnetically Levitated Pump Systems. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [125] Schönberger, J., Friedli, T., Round, S. D., and Kolar, J. W.: An Ultra Sparse Matrix Converter with a Novel Active Clamp Circuit. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [124] Kolar, J. W., Drofenik, U., Biela, J., Heldwein, M. L., Ertl, H., Friedli, T., and Round, S. D.: PWM Converter Power Density Barriers. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [123] Zwyssig, C., Duerr, M., Hassler, D., and Kolar, J. W.: An Ultra-HighSpeed, 500 000 rpm, 1 kW Electrical Drive System. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [122] Li, R., Xu, D., Chen, M., Feng, B., Mino, K., and Umida, H.: Improving the Power Density of the ZVS-SVM Controlled Three-Phase Boost PFC Converter. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007). [121] Nishida, Y., and Mino, K.: A Simple Passive PFC Scheme for ThreePhase Diode Rectifier. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 14244-0844-X, (2007). [120] Yamada, R., Kobayashi, N., and Mino, K.: A 1 kW Grid-Connected Converter System for PEFC. Proceedings of the 4th Power Conversion Conference (PCC‘07), Nagoya, Japan, April 2 – 5, CD-ROM, ISBN: 1-4244-0844-X, (2007).
[119] Nishida, Y., Miniböck, J., Round, S. D., and Kolar, J. W.: A New 3-phase Buck+Boost Unity Power Factor Rectifier with Two Independently Controlled DC Outputs. Proceedings of the 22nd IEEE Applied Power Electronics Conference, Anaheim (California), USA, Feb. 25 – March 1, Vol. 1, pp. 172-178 (2007). [118] Karutz, P., Round, S. D., Heldwein, M. L., and Kolar, J. W.: Ultra Compact Three-Phase PWM Rectifier. Proceedings of the 22nd IEEE Applied Power Electronics Conference, Anaheim (California), USA, Feb. 25 – March 1, Vol. 1, pp. 816-822 (2007). [117] Plesko, H., Biela, J., Luomi, J., and Kolar, J. W.: Novel Concepts for Integrating the Electric Drive and Auxiliary DC-DC Converter for Hybrid Vehicles. Proceedings of the 22nd IEEE Applied Power Electronics Conference, Anaheim (California), USA, Feb. 25 – March 1, Vol. 2, pp. 1025-1031 (2007). [116] Bortis, D., Biela, J., and Kolar, J. W.: Optimal Design of a DC Reset Circuit for Pulse Transformers. Proceedings of the 22nd IEEE Applied Power Electronics Conference, Anaheim (California), USA, Feb. 25 – March 1, Vol. 2, pp. 1171-1177 (2007). [115] Imoberdorf, P., Zwyssig, C., Round, S. D., and Kolar, J. W.: Combined Radial-Axial Magnetic Bearing for a 1kW, 500 000 rpm Permanent Magnet Machine. Proceedings of the 22nd IEEE Applied Power Electronics Conference, Anaheim (California), USA, Feb. 25 – March 1, Vol. 2, pp. 1434-1440 (2007). [114] Meili, J., Ponnaluri, S., Serpa, L., Steimer, P. K., and Kolar, J. W.: Optimized Pulse Patterns for the 5-Level ANPC Converter for High Speed High Power Applications. Proceedings of the 32nd Annual Conference of the IEEE Industry Electronics Society, Paris, France, Nov. 7 – 11, (2006). [113] Schönberger, J., Round, S., and Duke, R.: Autonomous Load Shedding in a Nanogrid using DC Bus Signalling. Proceedings of the 32nd Annual Conference of the IEEE Industry Electronics Society, Paris, France, Nov. 7 – 11, pp. 5155-5160 (2006). [112] Zwyssig, C., Round, S. D., and Kolar, J. W.: Analytical and Experimental Investigation of a Low Torque, Ultra-High Speed Drive System. Conference Record of the 2006 IEEE Industry Applications Conference, 41th IAS Annual Meeting (IAS‘06), Tampa (Florida), USA, Oct. 8 – 12, (2006). [111] Bartholet, M. T., Nussbaumer, T., Dirnberger, P., and Kolar, J. W.: Novel Converter Concept for Bearingless Slice Motor Systems. Conference Record of the 2006 IEEE Industry Applications Conference, 41th IAS Annual Meeting (IAS‘06), Tampa (Florida), USA, Oct. 8 – 12, (2006). [110] Schneeberger, T., and Kolar, J. W.: Novel Integrated Bearingless Hollow-Shaft Drive. Conference Record of the 2006 IEEE Industry Applications Conference, 41th IAS Annual Meeting (IAS‘06), Tampa (Florida), USA, Oct. 8 – 12, (2006). [109] Krismer, F., Round, S., and Kolar, J. W.: Performance Optimization of a High Current Dual Active Bridge with a Wide Operating Voltage Range. Proceedings of the 37th Power Electronics Specialists Conference, Jeju, Korea, June 18 – 22, CD ROM, ISBN: 1-4244-9717-7, (2006) [108] Serpa, L. A., Round, S., and Kolar, J. W.: A Virtual-Flux Decoupling Hysteresis Current Controller for Mains Connected Inverter Systems. Proceedings of the 37 th Power Electronics Specialists Conference, Jeju, Korea, June 18 – 22, CD ROM, ISBN: 1-4244-9717-7, (2006)
[107] Friedli, T., Heldwein, M. L., Giezendanner, F., and Kolar, J. W.: A High Efficiency Indirect Matrix Converter Utilizing RB-IGBTs. Proceedings of the 37 th Power Electronics Specialists Conference, Jeju, Korea, June 18 – 22, CD ROM, ISBN: 1-4244-9717-7, (2006) [106] Drofenik, U., and Kolar, J. W.: Analyzing the Theoretical Limits of Forced Air-Cooling by Employing Advanced Composite Materials with Thermal Conductivities > 400 W/mK. Proceedings of the 4th International Conference on Integrated Power Systems (CIPS‘06), Naples, Italy, June 7 – 9, pp. 323-328, (2006). [105] Ertl, H., Edelmoser, K., Zach. F. C., and Kolar, J. W.: A Novel Method for On-Line Monitoring and Managing of Electrolytic Capacitors of DC Voltage Link PWM Converters. Proceedings of the International PCIM Europe 2006 Conference, Nuremberg, Germany, May 30 – June 1 (2006). [104] Biela, J., Bortis, D., and Kolar, J. W.: Analytical Modelling of Pulse Transformers for Power Modulators. Proceedings of the 27 th IEEE International Power Modulator Symposium, Washington D.C., USA, May 14 – 18, (2006). [103] Heldwein, M. L., Ertl, H., Biela, J., and Kolar, J. W.: Implementation of a Transformer-Less Common Mode Active Filter for Off-Line Converter Systems. Proceedings of the 21st Annual IEEE Applied Power Electronics Conference and Exposition (APEC‘06), Dallas (Texas), USA, March 19 – 23, Vol. 2, pp. 1230-1236, (2006). [102] Biela, J., Wirthmueller, A., Waespe, R., Heldwein, M. L., Kolar, J. W., and Waffenschmidt, E.: Passive and Active Hybrid Integrated EMI Filters. Proceedings of the 21st Annual IEEE Applied Power Electronics Conference and Exposition (APEC‘06), Dallas (Texas), USA, March 19 – 23, Vol. 2, pp. 1174-1180, (2006). [101] Dalessandro, L., Karrer, N., and Kolar, J. W.: A Novel Isolated Current Sensor for High-Performance Power Electronics Applications. Proceedings of the 21st Annual IEEE Applied Power Electronics Conference and Exposition (APEC‘06), Dallas (Texas), USA, March 19 – 23, Vol. 1, pp. 559-566, (2006). [100] Gong, G., Ertl, H., and Kolar, J. W.: A Multi-Cell Cascaded Power Amplifier. Proceedings of the 21st Annual IEEE Applied Power Electronics Conference and Exposition (APEC‘06), Dallas (Texas), USA, March 19 – 23, Vol. 3, pp. 1550-1556, (2006). [99] Nussbaumer, T., Heldwein, M. L., and Kolar, J. W.: Common Mode EMC Input Filter Design for a Three-Phase Buck-Type PWM Rectifier System. Proceedings of the 21st Annual IEEE Applied Power Electronics Conference and Exposition (APEC‘06), Dallas (Texas), USA, March 19 – 23, Vol. 3, pp. 1617-1623, (2006). [98] Zwyssig, C., Round, S. D., and Kolar, J. W.: Power Electronics Interface for a 100 W, 500 000 rpm Gas Turbine Portable Power Unit. Proceedings of the 21st Annual IEEE Applied Power Electronics Conference and Exposition (APEC‘06), Dallas (Texas), USA, March 19 – 23, Vol. 1, pp. 283-289, (2006). [97] Schneider, B., Bruderer, M., Dyntar, D., Zwyssig, C., Diener, M., Boulouchos, K., Abhari, R. S., Guzzella, L., and Kolar, J. W.: Ultra-High-Energy-Density Converter for Portable Power. Proceedings of the 5th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2005), Tokyo, Japan, Nov. 28 – 30, pp. 81-84 (2005). 47
[96] Zwyssig, C., and Kolar, J. W.: Design Considerations and Experimental Results of a 100 W, 500 000 rpm Electrical Generator. Proceedings of the 5th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2005), Tokyo, Japan, Nov. 28 – 30, pp. 169-172 (2005). [95] Biela, J., and Kolar, J. W.: Using Transformer Parasitics for Resonant Converters – A Review of the Calculation of the Stray Capacitance of Transformers. Conference Record of the 2005 IEEE Industry Applications Conference, 40th IAS Annual Meeting (IAS‘05), Hong Kong, Oct. 2 – 6, CD-ROM, ISBN: 0-7803-9209-4 (2005). [94] Serpa, L. A., Kolar, J. W., Ponnaluri, S., and Barbosa, P. M.: A Modified Direct Power Control Strategy Allowing the Connection of ThreePhase Inverter to the Grid through LCL Filters. Conference Record of the 2005 IEEE Industry Applications Conference, 40th IAS Annual Meeting (IAS‘05), Hong Kong, Oct. 2 – 6, CD-ROM, ISBN: 0-7803-9209-4 (2005). [93] Krismer, F., Biela, J., and Kolar, J. W.: A Comparative Evaluation of Isolated Bi-directional DC/DC Converters with Wide Input and Output Voltage Range. Conference Record of the 2005 IEEE Industry Applications Conference, 40th IAS Annual Meeting (IAS‘05), Hong Kong, Oct. 2 – 6, CD-ROM, ISBN: 0-7803-9209-4 (2005). [92] Zwyssig, C., Kolar, J. W., Thaler, W., and Vohrer, M.: Design of a 100 W, 500 000 rpm Permanent-Magnet Generator for Mesoscale Gas Turbines. Conference Record of the 2005 IEEE Industry Applications Conference, 40th IAS Annual Meeting (IAS‘05), Hong Kong, Oct. 2 – 6, CD-ROM, ISBN: 0-7803-9209-4 (2005). [91] Nussbaumer, T., Gong, G., Heldwein, M. L., and Kolar, J. W.: Control-Oriented Modeling and Robust Control of a Three-Phase Buck+Boost PWM Rectifier (VRX-4). Conference Record of the 2005 IEEE Industry Applications Conference, 40th IAS Annual Meeting (IAS‘05), Hong Kong, Oct. 2 – 6, CD-ROM, ISBN: 0-7803-9209-4 (2005). [90] Nussbaumer, T., Heldwein, M. L., Gong, G., and Kolar, J. W.: Prediction Techniques Compensating Delay Times Caused by Digital Control of a Three-Phase Buck-Type PWM Rectifier System. Conference Record of the 2005 IEEE Industry Applications Conference, 40th IAS Annual Meeting (IAS‘05), Hong Kong, Oct. 2 – 6, CD-ROM, ISBN: 0-7803-9209-4 (2005). [89] Round, S., Heldwein, M. L., Kolar, J. W., Hofsajer, I., and Friedrichs, P.: A SiC JFET Driver for a 5 kW, 150 kHz Three-Phase Sinusoidal-Input, Sinusoidal-Output PWM Converter. Conference Record of the 2005 IEEE Industry Applications Conference, 40th IAS Annual Meeting (IAS‘05), Hong Kong, Oct. 2 – 6, CD-ROM, ISBN: 0-7803-9209-4 (2005). [88] Hofsajer, I. W., Melkonyan, A., Mantel, M., Round, S., and Kolar, J. W.: A Simple, Low Cost Gate Drive Method for Practical Use of SiC JFETs in SMPS. Proceedings of the 11th European Conference on Power Electronics and Applications, Dresden, Germany, Sept. 12 – 14, ISBN: 90-75815-08-5, P.1 - P.6 (2005) [87] Dalessandro, L., Odendaal, W. G., and Kolar, J. W.: HF Characterization and Non-Linear Modeling of a Gapped Toroidal Magnetic Structure. Proceedings of the 36th Power Electronics Specialists Conference, Recife, Brasil, June 12 – 16, Vol. 2, pp. 1250-1257 (2005)
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[86] Cavalcante, F., and Kolar, J. W.: Small-Signal Model of a 5 kW HighOutput Voltage Capacitive-Loaded Series-Parallel Resonant DC-DC Converter. Proceedings of the 36th Power Electronics Specialists Conference, Recife, Brazil, June 12 – 16 (2005) [85] Gong, G., Round, S., and Kolar, J. W.: Design, Control and Performance of Tracking Power Supply for a Linear Power Amplifier. Proceedings of the 36th Power Electronics Specialists Conference, Recife, Brazil, June 12 – 16 (2005) [84] Zhao, C., Round, S., and Kolar, J. W.: Buck and Boost Start-up Operation of a Three-Port Power Supply for Hybrid Vehicle Applications. Proceedings of the 36th Power Electronics Specialists Conference, Recife, Brazil, June 12 – 16, (2005) [83] Nascimento, C. B., Perin, A. J., and Pereira, E. I.: Low Cost High Power Factor Electronic Ballast with no Input Filter. Proceedings of the 36th Power Electronics Specialists Conference, Recife, Brazil, June 12 – 16, (2005) [82] Round, S. D., Dalessandro, L., and Kolar, J. W.: Novel Phase Decoupling and Coordinating Tolerance Band Current Control for Three-Phase Three-Level PWM Rectifiers. Proceedings of the International PCIM Europe 2005 Conference, Nuremberg, Germany, June 7 – 9, pp. 285-291 (2005). [81] Drofenik, U., Laimer, G., and Kolar, J. W.: Theoretical Converter Power Density Limits for Forced Convection Cooling. Proceedings of the International PCIM Europe 2005 Conference, Nuremberg, Germany, June 7 – 9, pp. 608-619 (2005). [80] Ertl, H., Zach, F. C., and Kolar, J. W.: Dimensioning and Control of a Switch-Mode Power Amplifier Employing a Capacitice Coupled Linear-Mode Ripple Suppression Stage. Proceedings of the International PCIM Europe 2005 Conference, Nuremberg, Germany, June 7 – 9, pp. 277 - 284 (2005). [79] Mino, K., Nishida, Y., and Kolar, J. W.: Novel Hybrid 12-Pulse Line Interphase Transformer Boost-Type Rectifier with Controlled Output Voltage and Sinusoidal Utility Currents. Proceedings of the 2005 International Power Electronics Conference (IPEC‘05), Niigata, Japan, April 4 – 8, CD-ROM, ISBN: 4-88686-065-6 (2005). [78] Biela, J., and Kolar, J. W.: Analytic Design Method for (Integrated-) Transformers of Resonant Converters using Extended Fundamental Frequency Analysis. Proceedings of the 2005 International Power Electronics Conference (IPEC‘05), Niigata, Japan, April 4 – 8, CD-ROM, ISBN: 4-88686-065-6 (2005). [77] Drofenik, U., and Kolar, J. W.: A General Scheme for Calculating Switching- and Conduction-Losses of Power Semiconductors in Numerical Circuit Simulations of Power Electronic Systems. Proceedings of the 2005 International Power Electronics Conference (IPEC‘05), Niigata, Japan, April 4 – 8, CD-ROM, ISBN: 4-88686-065-6 (2005). [76] Drofenik, U., and Kolar, J. W.: A Thermal Model of a Forced-Cooled Heat Sink for Transient Temperature Calculations Employing a Circuit Simulator. Proceedings of the 2005 International Power Electronics Conference (IPEC‘05), Niigata, Japan, April 4 – 8, CD-ROM, ISBN: 488686-065-6 (2005).
[75] Round, S., Schafmeister, F., Heldwein, M. L., Pereira, E., Serpa, L., and Kolar, J. W.: Comparison of Performance and Realization Effort of a Very Sparse Matrix Converter to a Voltage DC Link PWM Inverter with Active Front End. Proceedings of the 2005 International Power Electronics Conference (IPEC‘05), Niigata, Japan, April 4 – 8, CD-ROM, ISBN: 4-88686-065-6 (2005). [74] Mori, Y., Aikawa, N., Nishida, Y., Drofenik, U., and Kolar, J. W.: Development of an Interactive Circuits and Systems Seminar (iCASS) and Its Effectiveness. Proceedings of the 2005 International Power Electronics Conference (IPEC‘05), Niigata, Japan, April 4 – 8, CD-ROM, ISBN: 4-88686-065-6 (2005). [73] Heldwein, M. L., Nussbaumer, T., Beck, F., and Kolar, J. W.: Novel Three-Phase CM/DM Conducted Emissions Separator. Proceedings of the 20th Annual IEEE Applied Power Electronics Conference and Exposition, Austin (Texas), USA, March 6 – 10, Vol. 2, pp. 797-802 (2005). [72] Dalessandro, L., Drofenik, U., Round, S. D., and Kolar, J. W.: A Novel Hysteresis Current Control for Three-Phase Three-Level PWM Rectifiers. Proceedings of the 20th Annual IEEE Applied Power Electronics Conference and Exposition, Austin (Texas), USA, March 6 – 10, Vol. 1, pp. 501-507 (2005). [71] Laimer, G., and Kolar, J. W.: Design and Experimental Analysis of a DC to 1 MHz Closed Loop Magnetoresistive Current Sensor. Proceedings of the 20th Annual IEEE Applied Power Electronics Conference and Exposition, Austin (Texas), USA, March 6 – 10, Vol. 2, pp. 1288-1292 (2005). [70] Mino, K., Heldwein, M. L., and Kolar, J. W.: Ultra Compact ThreePhase Rectifier with Electronic Smoothing Inductor. Proceedings of the 20th Annual IEEE Applied Power Electronics Conference and Exposition, Austin (Texas), USA, March 6 – 10, Vol. 1, pp. 522-528 (2005). [69] Schafmeister, F., Rytz, C., and Kolar, J. W.: Analytical Calculation of the Conduction and Switching Losses of the Conventional Matrix Converter and the (Very) Sparse Matrix Converter. Proceedings of the 20th Annual IEEE Applied Power Electronics Conference and Exposition, Austin (Texas), USA, March 6 – 10, Vol. 2, pp. 875-881 (2005). [68] Drofenik, U., and Nishida, Y.: Web-Based Power Electronics Education Tool «iPES» Developed at the ETH Zurich. Proceedings of the Japan Industrial Applications Society Conference 2004 (in Japanese), Takamatsu, Japan, Sept. 14 – 16, CD-ROM. [67] Schafmeister, F., and Kolar, J. W.: Novel Hybrid Modulation Schemes Extending the Reactive Power Control Range of Conventional and Sparse Matrix Converters Operating at Maximum Output Voltage. Proceedings of the 11th International Power Electronics and Motion Control Conference, Riga, Latvia, Sept. 2 – 4, CD-ROM, ISBN: 9984-32-010-3 (2004). [66] Nussbaumer, T. , Heldwein, M. L., and Kolar, J. W.: Differential Mode EMC Input Filter Design for a Three-Phase Buck-Type Unity Power Factor PWM Rectifier. Proceedings of the 4th International Power Electronics and Motion Control Conference, Xian, China, Aug. 14 – 16, Vol. 3, pp. 1521-1526 (2004). [65] Mino, K., Gong, G., and Kolar, J. W.: Novel Hybrid 12-Pulse Line Interphase Transformer Boost-Type Rectifier with Controlled Output Voltage. Proceedings of the 4th International Power Electronics and Motion Control Conference, Xian, China, Aug. 14 – 16, Vol. 2, pp. 924-931 (2004).
[64] Nussbaumer, T. , Mino, K., and Kolar, J. W.: Design and Comparative Evaluation of Three-Phase Buck Boost and Boost Buck Unity Power Factor PWM Rectifier Systems for Supplying Variable DC Voltage Link Converters. Proceedings of the 10th European Power Quality Conference (PCIM), Nuremberg, Germany, May 25 – 27, Vol. 1, pp. 126-135 (2004). [63] Greul, R., Drofenik, U., and Kolar, J. W.: A Novel Concept for Balancing of the Phase Modules of a Three-Phase Unity Power Factor Y-Rectifier. Proceedings of the 35th IEEE Power Electronics Specialists Conference, Aachen, Germany, June 20 – 25, CD-ROM, ISBN: 07803-8400-8 (2004). [62] Drofenik, U., Laimer, G., and Kolar, J. W.: Pump Characteristic Based Optimization of a Direct Water Cooling System for a 10 kW/500 kHz Vienna Rectifier. Proceedings of the 35th IEEE Power Electronics Specialists Conference, Aachen, Germany, June 20 – 25, CD-ROM, ISBN: 07803-8400-8 (2004). [61] Schafmeister, F., and Kolar, J. W.: Novel Modulation Schemes for Matrix- and Sparse Matrix Converters Facilitating Reactive Power Transfer through the Converter System. Proceedings of the 35th IEEE Power Electronics Specialists Conference, Aachen, Germany, June 20 – 25, CD-ROM, ISBN: 07803-8400-8 (2004). [60] Zhao, C., and Kolar, J. W.: A Novel Three-Phase Three-Port UPS Employing a Single High-Frequency Isolation Transformer. Proceedings of the 35th IEEE Power Electronics Specialists Conference, Aachen, Germany, June 20 – 25, CD-ROM, ISBN: 07803-8400-8 (2004). [59] Heldwein, M. L., Nussbaumer, T., and Kolar, J. W.: Differential Mode EMC Input Filter Design for Three-Phase AC-DC-AC Sparse Matrix PWM Converters. Proceedings of the 35th IEEE Power Electronics Specialists Conference, Aachen, Germany, June 20 – 25, CD-ROM, ISBN: 07803-8400-8 (2004). [58] Biela, J., and Kolar, J. W.: Design of High Power Electromagnetic Integrated Transformers by means of Reluctance Models and a Structured Survey of Leakage Paths. Proceedings of the 35th IEEE Power Electronics Specialists Conference, Aachen, Germany, June 20 – 25, CD-ROM, ISBN: 07803-8400-8 (2004). [57] Ide, P., Schafmeister, F., Fröhleke, N., and Grotstollen, H.: Enhanced Control Scheme for Three-Phase / Three-Level Rectifiers at Partial Load. Proceedings of the 35th IEEE Power Electronics Specialists Conference, Aachen, Germany, June 20 – 25, CD-ROM, ISBN: 078038400-8 (2004). [56] Gong, G., Heldwein, M.L., Drofenik, U., Mino, K., and Kolar, J. W.: Comparative Evaluation of Three-Phase High Power Factor AC-DC Coverter Concepts for Application in Future More Electric Aircraft. Proceedings of the 19th Annual IEEE Applied Power Electronics Conference and Exposition, Anaheim (California), USA, February 22 – 26, Vol. 2, pp. 1152-1159 (2004). [55] Heldwein, M. L. , and Kolar, J. W.: A Novel SiC J-FET Gate Drive Circuit for Sparse Matrix Converter Applications. Proceedings of the 19th Annual IEEE Applied Power Electronics Conference and Exposition, Anaheim (California), USA, February 22 – 26, Vol. 1, pp. 116-121 (2004). [54] Gong, G., Drofenik, U., and Kolar, J. W.: 12-Pulse Rectifier for More Electric Aircraft Applications. Proceedings of the 3rd International Conference on Industrial Technology, Maribor, Slovenia, Dec. 10 – 12, CD-ROM, ISBN: 0-7803-7853-9 (2003). 49
[53] Kolar, J. W., and Schafmeister, F.: Novel Modulation Schemes Minimizing the Switching Losses of Sparse Matrix Converters. Proceedings of the 29th Annual Conference of the IEEE Industry Electronics Society, Roanoke (VA), USA, Nov. 2 – 6, pp. 2085-2090 (2003). [52] Mino, K., Herold, S., and Kolar, J. W.: A Gate Drive Circuit for Silicon Carbide JFET. Proceedings of the 29th Annual Conference of the IEEE Industry Electronics Society, Roanoke (VA), USA, Nov. 2 – 6, pp. 1162-1166 (2003). [51] Drofenik, U., and Kolar, J. W.: Thermal Analysis of a Multi-Chip Si/ SiC-Power Module for Realization of a Bridge Leg of a 10kW Vienna Rectifier. Proceedings of the 25th IEEE International Telecommunications Energy Conference, Yokohama, Japan, Oct. 19 – 23, pp. 826-833 (2003). [50] Laimer, G., and Kolar, J. W.: ‚Zero‘-Ripple EMI Input Filter Concepts for Application in a 1-U 500kHz Si/SiC Three-Phase PWM Rectifier. Proceedings of the 25th IEEE International Telecommunications Energy Conference, Yokohama, Japan, Oct. 19 – 23, pp. 750-756 (2003). [49] Greul, R., Drofenik, U., and Kolar, J. W.: Analysis and Comparative Evaluation of a Three-Phase Unity Power Factor Y-Rectifier. Proceedings of the 25th IEEE International Telecommunications Energy Conference, Yokohama, Japan, Oct. 19 – 23, pp. 421-428 (2003). [48] Nussbaumer, T., and Kolar, J. W.: Advanced Modulation Scheme for Three-Phase Three-Switch Buck-Type PWM Rectifier Preventing Mains Current Distortion Originating from Sliding Input Filter Capacitor Voltage Intersections. Proceedings of the 34th IEEE Power Electronics Specialists Conference, Acapulco, Mexico, June 15 – 19, Vol. 3, pp. 1086-1091 (2003). [47] Baumann, M., and Kolar, J. W.: A Novel Control Concept for Reliable Operation of a Three-Phase Three-Switch Buck-Type Unity Power Factor Rectifier with Integrated Boost Output Stage under Heavily Unbalanced Mains Condition. Proceedings of the 34th IEEE Power Electronics Specialists Conference, Acapulco, Mexico, June 15 – 19, Vol. 1, pp. 3-10 (2003). [46] Cavalcante, F., and Kolar, J. W.: Design of a 5kW High Output Voltage Series-Parallel Resonant DC-DC Converter. Proceedings of the 34th IEEE Power Electronics Specialists Conference, Acapulco, Mexico, June 15 – 19, Vol. 4, pp. 1807-1814 (2003). [45] Gong, G., Ertl, H., and Kolar, J. W.: High-Frequency Isolated DC/DC Converter for Input Voltage Conditioning of a Linear Power Amplifier. Proceedings of the 34th IEEE Power Electronics Specialists Conference, Acapulco, Mexico, June 15 – 19, Vol. 4, pp. 1929-1934 (2003). [44] Drofenik, U., Gong, G., and Kolar, J. W.: A Novel Bi-Directional ThreePhase Active Third-Harmonic Injection High Input Current Quality AC-DC Converter. Proceedings of the 9th European Power Quality Conference (PCIM), Nuremberg, Germany, May 20 – 22, pp. 243-254 (2003). [43] Ertl, J., Wiesinger, T., Kolar, J. W., and Zach, F. C.: A Simple Active Method to Avoid the Balancing Losses of DC Link Capacitors. Proceedings of the 47 th European Power Electronics Conference (PCIM), Nuremberg, Germany, May 20 – 22, pp. 459-464 (2003). [42] Greul, R., and Kolar, J. W.: Experimental Analysis of a 10kW Wide Input Voltage Range Modular Three-Phase Unity Power Factor PWM Delta-Rectifier. Proceedings of the 9th European Power Quality Conference (PCIM), Nuremberg, Germany, May 20 – 22 (2003).
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[41] Baumann, M., and Kolar, J. W.: A 5 kW Three-Phase Buck Boost Telecommunications Power Supply Module Input Stage Maintaining Unity Power Factor Under Failure of a Mains Phase. Proceedings of the 9th European Power Quality Conference (PCIM), Nuremberg, Germany, May 20 – 22, pp. 291-298 (2003). [40] Kolar, J. W., Miniböck, J., and Baumann, M.: Three-Phase PWM Power Conversion – The Route to Ultra High Power Density and Efficiency. Proceedings of the 2003 CPES Annual Seminar/Industry Review, Blacksburg (VA), USA, April 27 - 29, (2003). [39] Schafmeister, F., Herold, S., and Kolar, J. W.: Evaluation of 1200VSi-IGBTs and 1300 V-SiC-JFETs for Application in Three-Phase Very Sparse Matrix AC-AC Converter Systems. Proceedings of the 18th Annual IEEE Applied Power Electronics Conference and Exposition, Miami Beach (Florida), USA, February 9 – 13, Vol. 1, pp. 241-255 (2003). [38] Drofenik, U., and Kolar, J. W.: Teaching Thermal Design of Power Electronic Systems with Web-Based Interactive Educational Software. Proceedings of the 18th Annual IEEE Applied Power Electronics Conference and Exposition, Miami Beach (Florida), USA, February 9 – 13, Vol. 2, pp. 1029-1037 (2003). [37] Cavalcante, F., and Barbi, I.: A New Dimmable 70 W Electronic Ballast for High Pressure Sodium Lamps. Conference Record of the 2002 IEEE Industry Applications Conference. 37 th IAS Annual Meeting, Pittsburgh (Pennsylvania), USA, Oct. 13 – 17, Vol. 3, pp. 1856-1862 (2002). [36] Baumann, M., and Kolar, J. W.: Experimental Evaluation of Space Vector Orientated Active DC-Side Current Balancing of Two Parallel Connected Three-Phase Three-Switch Buck-Type Unity Power Factor Rectifier Systems. Proceedings of the 24th IEEE International Telecommunications Energy Conference, Montreal, Canada, Sept. 29 – Oct. 3, pp. 317-324 (2002). [35] Schafmeister, F., and Kolar, J. W.: Analyse der Regelung einer permanenterregten Synchronmaschine bei Speisung durch einen dreiphasigen Sparse-Matrix-Konverter. Ansoft‘s Inspiring Design Worldwide Workshop, Stuttgart, Germany, Oct. 8 (2002). [34] Lindemann, A., Baumann, M., and Kolar, J. W.: Comparison of Different Bidirectional Bipolar Switches for Use in Sparse Matrix Converters. Proceedings of the 10th International Power Electronics and Motion Control Conference, Dubrovnik, Croatia, Sept. 9 – 11, CD-ROM, ISBN: 953-184-047-4 (2002). [33] Drofenik, U., and Kolar, J. W.: Teaching Basics of Inductive Power Components Using Interactive Java Applets Performing FEM-Based On-Line Calculation of the Magnetic Flux Distribution. Proceedings of the 10th International Power Electronics and Motion Control Conference, Dubrovnik, Croatia, Sept. 9 – 11, CD-ROM, ISBN: 953-184047-4 (2002). [32] Schafmeister, F., Baumann, M., and Kolar, J. W.: Analytically Closed Calculation of the Conduction and Switching Losses of Three-Phase AC-AC Sparse Matrix Converters. Proceedings of the 10th International Power Electronics and Motion Control Conference, Dubrovnik, Croatia, Sept. 9 – 11, CD-ROM, ISBN: 953-184-047-4 (2002). [31] Nishida, Y., Drofenik, U., and Kolar, J. W.: Interactive Animation Program for Power Electronics Education and Self-Learning. Proceedings of the 2002 Annual Conference IEE Japan (in Japanese), Kagoshima, Japan, August 21 – 23, CD-ROM (2002).
[30] Nussbaumer, T., and Kolar, J. W.: Comparative Evaluation of Control Techniques for a Three-Phase Three-Switch Buck-Type AC-to-DC PWM Converter System. Proceedings of the 3rd IEEE Nordic Workshop on Power and Industrial Electronics, Stockholm, Sweden, Aug. 12 – 14, CD-ROM, ISSN: 1650 674x (2002). [29] Laimer, G., and Kolar, J. W.: Wide Bandwidth Low Complexity Isolated Current Sensor to be Employed in a 10 kW/500 kHz Three-Phase Unity Power Factor PWM Rectifier System. Proceedings of the 33rd IEEE Power Electronics Specialists Conference, Cairns, Australia, June 23 – 27, Vol. 3, pp. 1065-1070 (2002). [28] Drofenik, U., and Kolar, J. W.: Interactive Power Electronics Seminar (iPES) - A Web-Based Introductory Power Electronics Course Employing Java-Applets. Proceedings of the 33rd IEEE Power Electronics Specialists Conference, Cairns, Australia, June 23 – 27, Vol. 2, pp. 443-448 (2002). [27] Baumann, M., and Kolar, J. W.: Analysis of the Effects of Non-Idealities of Power Components and Mains Voltage Unbalance on the Operating Behavior of a Three-Phase/Switch Buck-Type Unity Power Factor PWM Rectifier. Proceedings of the 33rd IEEE Power Electronics Specialists Conference, Cairns, Australia, June 23 – 27, Vol. 4, pp. 1607-1612 (2002). [26] Miniböck, J., and Kolar, J. W.: Wide Input Voltage Range High Power Density High Efficiency 10 kW Three-Phase Three-Level Unity Power Factor PWM Rectifier. Proceedings of the 33rd IEEE Power Electronics Specialists Conference, Cairns, Australia, June 23 – 27, Vol. 4, pp. 16421648 (2002). [25] Miniböck J., and Kolar J. W.: A Novel 10 kW 2-U Three-Phase Unity Power Factor Rectifier Module. Proceedings of the 2nd International Conference on Integrated Power Systems, Bremen, Germany, June 11 – 12, pp. 19-23 (2002). [24] Miniböck, J., and Kolar, J. W.: A Highly Versatile Laboratory Setup for Teaching Basics of Power Electronics in Industry Related Form. Proceedings of the 8th European Power Quality Conference (PCIM), Nuremberg, Germany, May 14 – 16, pp. 119-123 (2002). [23] Laimer, G., and Kolar, J. W.: Accurate Measurement of the Switching Losses of Ultra High Switching Speed CoolMOS Power Transistor/SiC Diode Combination Employed in Unity Power Factor PWM Rectifier Systems. Proceedings of the 8th European Power Quality Conference (PCIM), Nuremberg, Germany, May 14 – 16, pp. 71-78 (2002). [22] Ertl, J., Kolar J. W., Morauf, G., and Zach, F. C.: Analysis of Active Ripple Current Compensators Employing Multi-Cell Switch-Mode Amplifier Topologies. Proceedings of the 8th European Power Quality Conference (PCIM), Nuremberg, Germany, May 14 – 16, pp. 125-131 (2002). [21] Baumann, M., and Kolar, J. W.: DC Side Current Balancing of Two Parallel Connected Interleaved Three-Phase Three-Switch Buck-Type Unity Power Factor PWM Rectifier Systems. Proceedings of the 8th European Power Quality Conference (PCIM), Nuremberg, Germany, May 14 – 16, pp. 63-70 (2002). [20] Drofenik, U., and Kolar, J. W.: Modern and Intuitive Way of Teaching Space Vector Calculus and PWM in an Undergraduate Course. Proceedings of the 3rd Power Conversion Conference, Osaka, Japan, April 2 – 5, Vol. 1, pp. 305-310 (2002).
[19] Baumann, M., and Kolar, J. W.: Minimization of the DC Current Ripple of a Three-Phase Buck Boost PWM Unity Power Factor Rectifier. Proceedings of the 3rd IEEE Power Conversion Conference, Osaka, Japan, April 2 – 5, Vol. 2, pp. 472-477 (2002). [18] Miniböck, J., Greul, R., and Kolar, J. W.: A Novel Control Concept for Operating a Two-Stage Delta-Rectifier-Based Telecommunications Power Supply Module under Heavily Unbalanced Mains Voltage Conditions. Proceedings of the 17 th Annual IEEE Applied Power Electronics Conference and Exposition, Dallas (Texas), USA, March 10 – 14, Vol. 2, pp. 716-721 (2002). [17] Kolar, J. W., Baumann, M., Schafmeister, F., and Ertl, H.: Novel ThreePhase AC-DC-AC Sparse Matrix Converter. Part I - Derivation, Basic Principle of Operation, Space Vector Modulation, Dimensioning. Proceedings of the 17 th Annual IEEE Applied Power Electronics Conference and Exposition, Dallas (Texas), USA, March 10 – 14, Vol. 2, pp. 777-787 (2002). [16] Drofenik, U., and Kolar, J. W.: Survey of Modern Approaches of Education in Power Electronics. Proceedings of the 17 th Annual IEEE Applied Power Electronics Conference and Exposition, Dallas (Texas), USA, March 10 – 14, Vol. 2, pp. 749-755 (2002). [15] Baumann, M., Stögerer, F., and Kolar, J. W.: Novel Three-Phase ACDC-AC Sparse Matrix Converter. Part II – Experimental Analysis of the Very Sparse Matrix Converter. Proceedings of the 17 th Annual IEEE Applied Power Electronics Conference and Exposition, Dallas (Texas), USA, March 10 – 14, Vol. 2, pp. 788-791 (2002). [14] Miniböck, J., Greul, R., and Kolar, J. W.: Evaluation of a DeltaConnection of Three Single-Phase Unity Power Factor Rectifier Modules (Delta-Rectifier) in Comparison to a Direct Three-Phase Rectifier Realization. Part II – Components Stress Evaluation, Efficiency, Control. Proceedings of the 23rd IEEE International Telecommunications Energy Conference, Edinburgh, United Kingdom, Oct. 14 – 18, pp. 446-454 (2001). [13] Baumann, M., and Kolar, J. W.: Experimental Analysis of a 5 kW Wide Input Voltage Range Three-Phase Buck Boost Power Factor Corrector. Proceedings of the 23rd IEEE International Telecommunications Energy Conference, Edinburgh, United Kingdom, Oct. 14 – 18, pp. 146-153 (2001). [12] Drofenik, U., Kolar, J. W., van Duijsen, P.J., and Bauer, P.: New Web-Based Interactive E-Learning in Power Electronics and Electrical Machines. Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting, Chicago (Illinois), USA, Sept. 30 – Oct. 4, Vol. 3, pp. 1858-1865 (2001). [11] Miniböck, J., and Kolar, J. W.: Experimental Analysis of the Application of Latest SiC Diode and CoolMOS Power Transistor Technology in a 10kW Three-Phase PWM (VIENNA) Rectifier. Proceedings of the 43rd International Power Electronics Conference (PCIM), Nuremberg, Germany, June 19 – 21, pp. 121-125 (2001). [10] Kolar, J. W., Stögerer, F., and Nishida, Y.: Evaluation of a DeltaConnection of Three Single-Phase Unity Power Factor Rectifier Systems (Delta-Rectifier) in Comparison to a Direct Three-Phase Rectifier Realization. Part I – Modulation Schemes and Input Current Ripple. Proceedings of the 7 th European Power Quality Conference (PCIM), Nuremberg, Germany, June 19 – 21, pp. 101-108 (2001).
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Ertl, H., Kolar, J. W., and Zach, F.C.: A Novel Multi-Cell DC-AC Converter for Applications in Renewable Energy Systems. Proceedings of the 43rd International Power Electronics Conference (PCIM), Nuremberg, Germany, June 19 – 21, pp. 579-586 (2001). Baumann, M., and Kolar, J. W.: Experimental Evaluation of a ThreePhase Three-Switch Buck-Type Unity Power Factor Corrector. Proceedings of the 7 th European Power Quality Conference (PCIM), Nuremberg, Germany, June 19 – 21, pp. 69-75 (2001). Stögerer, F., Miniböck, J., and Kolar, J. W.: Design and Experimental Verification of a Novel 1.2 kW 480 Vdc/24 Vac Two-Switch Three-Phase DCM Flyback-Type Unity Power Factor Rectifier. Proceedings of the 32nd Power Electronics Specialists Conference, Vancouver, Canada, June 17 – 21, Vol. 2, pp. 914-919 (2001). Stögerer, F., Miniböck, J., and Kolar, J. W.: Implementation of a Novel Control Concept for Reliable Operation of a VIENNA Rectifier under Heavily Unbalanced Mains Voltage Conditions. Proceedings of the 32nd Power Electronics Specialists Conference, Vancouver, Canada, June 17 – 21, Vol. 3, pp. 1333-1338 (2001). Miniböck, J., and Kolar, J. W.: Comparative Theoretical and Experimental Evaluation of Bridge Leg Topologies of a Three-Phase Three-Level Unity Power Factor Rectifier. Proceedings of the 32nd Power Electronics Specialists Conference, Vancouver, Canada, June 17 – 21, Vol. 3, pp. 1641-1646 (2001). Baumann, M., and Kolar, J. W.: Comparative Evaluation of Modulation Methods for a Three-Phase / Switch Buck Power Factor Corrector Concerning the Input Capacitor Voltage Ripple. Proceedings of the 32nd IEEE Power Electronics Specialists Conference, Vancouver, Canada, June 17 – 21, Vol. 3, pp. 1327-1333 (2001). Stögerer, F., Miniböck, J., and Kolar, J. W.: A Novel Concept for Mains Voltage Proportional Input Current Shaping of a VIENNA Rectifier Eliminating Controller Multipliers. Part II – Operation for Heavily Unbalanced Mains Phase Voltages and in Wide Input Voltage Range. Proceedings of the 16th IEEE Applied Power Electronics Conference, Anaheim (California), USA, March 4 – 8, Vol. 1, pp. 587-591 (2001). Miniböck, J., Stögerer, F., and Kolar, J. W.: A Novel Concept for Mains Voltage Proportional Input Current Shaping of a VIENNA Rectifier Eliminating Controller Multipliers. Part I – Basic Theoretical Considerations and Experimental Verification. Proceedings of the 16th IEEE Applied Power Electronics Conference, Anaheim (California), USA, March 4 – 8, Vol. 1, pp. 582-586 (2001). Baumann, M., Stögerer, F., Kolar, J. W., and Lindemann, A.: Design of a Novel Multi-Chip Power Module for a Three-Phase Buck+Boost Unity Power Factor Utility Interface Supplying the Variable Voltage DC Link of a Square-Wave Inverter Drive. Proceedings of the 16th IEEE Applied Power Electronics Conference, Anaheim (California), USA, March 4 – 8, Vol. 2, pp. 820-827 (2001).
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