Power control in applications with a line voltage of 3kV DC and more today is managed by GTOs and. IGCTs. The IGBT, a device with several advantages ...
6.5kV IGBT-Modules Franz Auerbach (Infineon Technologies) Josef Georg Bauer (Siemens AG) Manfred Glantschnig (Infineon Technologies) Jürgen Göttert (eupec GmbH & Co KG) Martin Hierholzer (eupec GmbH & Co KG) Alfred Porst (Infineon Technologies) Daniel Reznik (Siemens AG) Hans-Joachim Schulze (Siemens AG) Thomas Schütze (eupec GmbH & Co KG) Reinhold Spanke (eupec GmbH & Co KG)
Power control in applications with a line voltage of 3kV DC and more today is managed by GTOs and IGCTs. The IGBT, a device with several advantages compared to power semiconductors in thyristor structure (low requirements regarding the driving unit, easy cooling as a result of the isolated structure) is fully developed and introduced up to a blocking voltage range of 3.3kV. Consequently, at the moment IGBT-technology can only be used by series connection of at least two IGBT-modules in these high voltage applications. This leads to several complications in driving, controlling and isolating the modules. With the development of 6.5kV IGBT-modules, eupec makes a power semiconductor available, which combines the advantages of IGBT-technology with the high blocking voltage capability of GTOs and IGCTs without the problems of series connection.
Applications for 6.5kV-IGBT-Modules
up by connecting the semiconductors directly
The 6.5kV-IGBT-modules are basically de-
to the DC-link. Applications in 4.16 kV AC-lines
signed for traction applications working at a
(5.9kV DC-link) can be realised by series
voltage level of 3kV DC. Because of the high
connection or in three level circuit designs.
blocking voltage capability the margin for over-
To cover all the various demands of industrial
voltage spikes during turn-off is large enough,
and traction applications concerning DC-link
even under worst case conditions, where the
voltage, voltage fluctuation and circuit stray
DC-link voltage can increase up to 4.5kV as a
inductance, a switch with a high blocking vol-
matter of voltage fluctuation (30% of nominal
tage capability as given by 6.5kV-IGBT-
DC-link) and regeneration. Even in this case a
modules is necessary.
save operation at turn-off is guaranteed for total stray inductance of 200nH and a di/dt of
Design of 6.5kV chips
10kA/µsec.
Both IGBT and diode chips designed by In-
The conditions are even worse in industrial
fineon Technologies (former Siemens semi-
environment, the second major field of appli-
conductor division) are based on the NPT
cation for 6.5kV-IGBT-modules. Converters in
concept.
IGBT technology for an AC line voltage of 2.3
An NPT chip has to be at least as thick as the
kV (DC-link voltage 3.25kV) can easily be set
maximum expansion of the depletion zone
which is given by the doping concentration of -
the n base zone and the blocking voltage. For
tribution of the forward voltage drop VCEsat and VF of the NPT technology.
6.5kV chips this would lead to an enormous wafer thickness. Consequently the forward
Housing concept
voltage drop and with it the on-state losses
The housing of 6.5kV-IGBT-modules is based
would exceed any manageable level. With the
on the eupec concept for high power modules
introduction of a vertically optimised device
to meet a standard, which is well introduced all
structure the wafer thickness could be reduced
over the world (figure 2). The baseplate di-
gaining significantly improved on-state voltage
mensions are similar to the 3.3kV module
and switching energies without losing blocking
family. Therefore already existing inverter
voltage capability.
designs for IHM and IHV modules can easily
During turn-off the current waveform shows
be adapted to the new 6.5 kV-module [1].
differences to the known behaviour of NPT
The implementation of creepage and clearance
IGBTs (see figure 1). The length of the turn-off
distances is realised by increasing the height of
current tail could be reduced (current cut-off)
the module by 10mm.
as a consequence of the vertical optimisation which offers benefits in the turn-off energy. Nevertheless the new device structure implements well known NPT-specific features like positive temperature coefficient of the on-state voltage, short circuit capability
and high
ruggedness concerning overcurrent.
Tj = 125 °C IC = 40 A VCC = 4000 V
figure 1 : Current cut-off The whole chip process for both IGBT and diode does not need any epitaxial layer. All doping steps are realised by diffusion and implantation. Thus a precise doping control is possible which leads to the known narrow dis-
figure 2 : housing concept of FZ 600 R 65 KF1 To consider the most novel developments in reliability concerning temperature cycling capability, all modules are built with AlSiC-baseplates [2].
Highest demands have to be fulfilled to cover
As the modules are basically designed for
the requirements on insulation capability and
traction applications, high demands on tem-
partial discharge behaviour. The design of the
perature cycling capability have to be fulfilled.
insulation refers to the international standard
Consequently the construction of the modules
IEC 1287. To meet the requirements of all
takes into account the most novel develop-
applications, the modules have to withstand
ments like AlSiC baseplate and AlN substrates
10.2kVrms between the electrical terminals and
for an improved thermal management. Im-
the baseplate for 60 seconds (insulation
provements reached by eupec since the intro-
voltage test).
The partial discharge level is
duction of IGBTs in the fields of bonding and
below 10pC for 5.1kVrms. The values are based
baseplate technology as well as partial dis-
on the worst case conditions for 6.5kV-IGBT-
charge immunity are reported in [3].
modules in operation, which means that even a repetitive voltage peak of 6500V between any IC = f (VCEsat, Tj)
electrical terminal and the baseplate does not 2,0
exceed the limits given by IEC 1287. With the new housing concept, a further simtems is given to the customer. The position of
Tj = 25°C
1,6
Tj = 125°C
1,4
I / INenn
plification for the construction of bus-bar sys-
1,8
the holes for mounting and the load terminals
1,2 1,0 0,8 0,6
is compatible for all module sizes. Thus, the
0,4
construction of converters for different power
0,0
0,2 0,0
0,5
1,0
1,5
2,0
2,5
3,0
ranges based on 6.5kV technology is simpli-
3,5
4,0
4,5
5,0
5,5
6,0
6,5
7,0
7,5
VCEsat [V]
fied. figure 3 : forward voltage drop of 6.5kV-IGBT Features of 6.5kV-IGBT modules The 6.5kV-IGBT modules are based on the
IF = f (VF, T j)
NPT technology which makes them rugged for 2,0
short circuit and turn-off capability. The modules are designed for a maximum DC-link are able to turn-off double the rated current repetitive against 4.5kV DC-link and they are able to manage a short circuit for 10µsec and Tj = 125°C. Another advantage of NPT technology is the
Tj = 25°C
1,6
Tj = 125°C
1,4
I / INenn
voltage VCCmax = 4500V. That means that they
1,8
1,2 1,0 0,8 0,6 0,4 0,2 0,0 0,0 0,5
1,0
1,5 2,0
2,5
3,0
3,5
4,0
4,5
5,0 5,5 6,0
6,5 7,0 7,5
VF [V]
positive temperature coefficient of V CEsat and VF for nominal current (figure 3,4), a major benefit
figure 4 : forward voltage drop of 6.5kV-diode
for paralleling chips and modules. As a result of the vertically optimised device
As an additional benefit for the customer a gate
the forward voltage drop and the turn-off losses
driver unit which is especially designed for
of both IGBT and diode is kept low.
6.5kV-IGBT modules is under development.
Efficiency of 6.5kV-IGBT-modules
Conclusion
To quantify the efficiency of 6.5kV-IGBT-
Eupec presents a module range with a
modules, it is useful to compare an inverter in
blocking voltage capability of 6500V and rated
3.3kV technology with an inverter in 6.5kV
currents up to 600A. The electrical character-
technology for the same operation point. The
istics are determined from the advantages of
attention is directed to the maximum output
NPT-technology. The insulation is designed to
current.
withstand 10.2 kVrms between the electrical
Assuming an application with nominal DC-link
terminals and the baseplate and it is partial
voltage of 3000V with a maximum output peak
discharge-free up to a voltage of 5.1 kVrms to
current of approximately 1200A, a series con-
fulfil all international standards. The modules
nection of two FZ 1200 R 33 KF2 or a parallel
are built with AlSiC – baseplates and AlN-sub-
connection of two FZ 600 R 65 KF1 is neces-
strates to consider the most novel develop-
sary. The limit conditions should be
ments in reliability concerning temperature cycling capability.
TC = 80 °C,
With the development of the 6.5kV module
Tj,max = 125 °C,
generation, eupec underlines again its inno-
fswitch = 500 Hz,
vative strength and capability by setting a new
fout = 50 Hz,
standard in the uppermost IGBT power range.
cos φ = 0,9.
With the datasheet values of the 3.3kV-IGBT-
[1] : Thomas Schütze
module and the measurement results of 6.5kV-
Design Aspects for Inverters with IGBT High Power
IGBT-modules the simulation shows, that the
Modules, PCIM Hongkong, 1997
maximum
phase
current
Irms
and
as
a
consequence the output power can be increased by 25%, using the parallel connection of 6.5kV-modules.
[2] : H.P. Degisher, G. Lefranc, K.H.Sommer Al-SiC improves Reliability of IGBT Power Modules, Proc. ICCM 12, Paris 1999
[3] : Herrmann Berg, Martin Hierholzer, Thomas Schütze Further Improvements in the Reliability of IGBT
Product Overview
Modules, IAS St. Louis 1998
The 6.5kV module family will be represented by different module types and rated currents as it is already known from 3.3kV modules to supply a wide range of applications. With regard to the different baseplate sizes (73 2
2
x 140 mm , 130 x 140 mm and 190 x 140 2
mm ) three basic single switches are available with rated currents of 200A, 400A and 600A. Obligatory for all traction applications are chopper modules, which are represented by a 200A and a 400A device. Additionally three double diode modules of 200A, 400A and 600A are planned.
