Novel Type Half-Bridge Soft Switching PWM Inverter ... - IEEE Xplore

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welding power supplies, a soft switching dc-dc power. Abstract-This paper presents a new circuit topology ofdc bus converter with active switches in the primary ...
IEEE PEDS 2005

Advanced High Power DC-DC Converter using Novel Type Half-Bridge Soft Switching PWM Inverter with High Frequency Transformer for Arc Welder Keiki Morimoto Toshimitsu Doi Haruhiko Manabe Daihen Corporation, Osaka, Japan

[email protected]

Nabil A. Ahmed

Hyun - Woo Lee Mutsuo Nakaoka

Sophia University Tokyo, Japan

Kyungnam University, Masan, Korea

nabil~acc.aun.edu.eg

Abstract-This paper presents a new circuit topology of dc bus line switch-assisted half-bridge soft switching PWM inverter type

dc-dc converter for arc welder. The proposed power converter is composed of typical voltage source half-bridge high frequency PWM inverter with a high frequency transformer link in addition to dc bus line side power semiconductor switching devices for

PWM control scheme and capacitive lossless snubbers. All the active power switches in the half-bridge arm and dc bus lines can

achieve ZCS turn-on and ZVS turn-off commutation operation

and consequently the total turn-off switching losses can be significantly reduced. As a result, a high switching frequency of

using IGBTs can be actually selected more than about 10 kHz. The effectiveness of this new converter topology is proved for low voltage and large current dc-dc power supplies such as arc welder from a practical point of view.

Keywords-Dc-dc power converter, High frequency transformer link, Soft switching PWM arc welding machine, I. INTRODUCTION

A. Research Background Recently, saturable inductor assisted ZVS-PWM full-bridge high-frequency inverter link dc-dc power converter [1] and lossless capacitors and transformer parasitic inductive components assisted soft switching dc-dc power converter with phase-shifted modulation control scheme in secondary-side of high frequency transformer [2]-[5] have been developed and evaluated. These power converter circuit topologies are suitable for handling high output power more than about several kW, especially for high voltage and low current applications as new energy related power supplies. However, secondary magnetic switches or transformer secondary side semiconductor switching devices in these converter circuit topologies may cause large conduction loss when these power circuit topologies are adopted for low voltage and large current

application as arc welding power supplies. Therefore, for the low voltage and large current application required for arc

O-7803-9296-5/05/$20.00 © 2005 IEEE

nakaoka@pe-newsl .eee.yamaguchi-u.ac.jp

welding power supplies, a soft switching dc-dc power converter with active switches in the primary side of high frequency transformer is considered to be more suitable and

accele.A a circuit topologytf arc welder, authors developed the novel circuit topology of

voltage source full-bridge type soft switching PWM inverter in which all the active switches can actively achieve ZCS turn-on and ZVS turn-off commutation operation [6]-[10].

B. Research Objectives This paper presents a novel circuit topology of voltage source half-bridge type soft switching PWM inverter. Under the newly-proposed high frequency inverter link dc-dc power circuit, all the active switches in the half-bridge arm and dc bus lines can actively achieve ZCS turn-on and ZVS turn-off commutation The steady operation. state operating principle of the proposed soft switching PWM dc-dc power converter is described with its remarkable features. The experimental operation results ofthis new type of soft switching PWM dc-dc power converter using IGBT power modules are illustrated including power loss analysis as compared with that of the hard switching PWM dc-dc power converter. The practical effectiveness of the proposed high frequency transformer link dc-dc power converter acceptable and suitable for high power applications which is designed for low voltage and large current output is actually proved on the basis of experimental data.

II. NEW SOFT SWITCHING DC-DC CONVERTER Fig. 1 shows the proposed soft switching PWM dc-dc converter circuit using a novel type half-bridge soft switching PWM inverter with high frequency transformer link. Proposed converter is composed of typical voltage source half-bridge inverter with a active PWM switch Q3(S3/D3) in positive dc bus line and a active PWM switch Q4(S3/D3) in negative dc bus line

and two lossless snubbing capacitors C1, C2 and two diodes D5,

D6~Two centre points of two capacitors C1, 02 and two diodes

113

td td D5, D6 are connected to a mid point of two voltage sources El, E2 and one of terninals of primary winding of high frequency QI transformer. The voltage of two voltage sources El, E2 and capacitance of capacitors C1, C2 are designed so as to be equal td Q2 (E,=E2=E, C1 =C2 =C). The main active switches Q1(Sl/Dl) or r ne swithing peri Q2(S2/D2) can be turned on and turned off in accordance with modified PWM control circuit similar to conventional Q3Half switching p half-bridge type hard switching PWM inverter. Under the proposed soft switching dc-dc converter, the switches in the half-bridge type inverter can perform ZVS Qi turn-off transition due to the presence of the active PWM ' switches Q3 or Q4 which are turned off and the snubbing Fco T Duty Factor Ton4 capacitors C, or C2 are completely discharged before the active Ton4/Th = 2TonJ/Ts switches Q, or Q2 in half-bridge type inverter arms are turned Fig. 2 Pattern sequences of switching gate driving pulses. off. In addition, the inverter switches can also perform ZCS at a turn-on transition with the aid of inductance Ls, as a parasitic The gate voltage pulse slgnals for the inverter switches or leakage inductance of high frequency transformer HF-T. Q2 m voltage source half-bridge inverter arms are the same as As for the active PWM switches Q3 or Q4 in series with the . bus signal sequences of conventional half-bridge inverter. PWM civ dc s the turn-on gate voltage pulse signals to the dc bus Regarding tun- mode transition due to the lossless snubbing liesdsreswtcs ZVS at a turn-off 3oQ4thsgnsaeapidto3 orQt, the signals are applied to Q2 lie side seies switches capacitors C1 or C2. These active PWM switches Q3 or Q4 can Qt or Q2a sam g also achieve ZVS/ZCS at a turn-on mode transition due to the ti the t- sals toQo reQpeatite lossless snubbing capacitors C1 or C2, which have been of before the are delivered to Q3~oor Q4~bfr egho aedlvrdt h predetermined rdtrie length E2 of dc the halfvoltage charged up to the same voltage ascharged up to the E1or are turn-off the when signals samvotagasthehalvtime on the basis of the time td power bus line voltage source by the energy storage in the to Q or Q2 In otherwords, the turn-off pulse signals leakage inductance Ls after the half-bridge type inverter appied are applied to Qi or Q2 after the turn-off gate signals are switches are tued off completely. With the proposed soft switching PWM dc-dc converter B. Operation Modes circuit, although the conduction power loss of the additional Fig. 3 illustrates the relevant operating waveforms in a switches may increases the total power loss a little, the total complete switching period for the pulse pattern of gate drive turn-off switching loss of half-bridge type PWM inverter can timing sequences shown in Fig. 2. The operation modes are be significantly decreased with the optimum aid of dc bus line divided into seven operation modes from mode 0 to mode 6 in series switches Q3 or Q4 and the lossless snubbing capacitors C1 accordance with operational timing from to to t6 and each or C2. operation principle is described hereafter. The equivalent circuits corresponding to each mode are shown in Fig. 4. III. PRINCIPLE OF OPERATION

Qs

~ liesd,tePMcnrlldsice.a transtionld toitheo snubbing ZVScatau~~~~~ mode,te

A. Gate Voltage Pulse Timing Sequences Fig. 2 shows timing pattern sequences of switching gate driving pulses. S3

BF-T;(NI :N2:N3=4: 1:1)

1) Mode 0:

-o

Before time to, the switches Q, and Q3 are turned on. At this time, i4 flows through the primary winding of transformer HF-T. Also, iS, flows through Qi and i,3 flows through Q3. In this period, all currents ill, isi and i43 are equal and the voltage vcI across the capacitor Cl is the same as the dc bus line voltage

Ei. ModelI : t 1t Dsi~~~~~~~~2) Dsii time to, the turn-off signal is applied to Q3. At this time, the L °At TN2p"series switch Q3 in dc bus line can be turned off with ZVS UR Nl * 2 it l lt| because the current i13 through Q3 is immediately cut off due to HF-T lossless snubbing capacitor C1. After time to, the voltage vc, the D8 : sR, D ID8 E2 C2 Aii ED2 t> across the capacitor Cl discharges constantly toward zero Ql; (S/DI)) voltage from E1=E voltage. Q2; (S2/D2) At this time, the voltage vcJ across the lossless snubber Q3; (S3/D3) Q4; (S4/D4) capacitor C1 is estimated as, S4 T Vcl (t)=E- (itlIC)t

Fig. 1 Soft-switching PWM dc-dc converter using

a novel type half-bridge soft switching PWM

Inverter with high frequency link.

114

(1)

this voltage Vcl becomes zero is given by,

td

Qi

t--CE/itl

Q2

f

current i4l is small, the more the

to

Vc1 Vc2

time for capacitor C1 is short. On the other hand, the more the

l3

Q

ts

t6|

I: 1!/

[\

VC2 1 1

.

|| K2t3

S

T

1 U1 1 [:t4

Vs2

IA I

|

\

iS2 l

l

ll 1S3I,,_: I

lS4

ll

iS4 iDJ 1

1D6

|

Vab Vd

to t2, the diodes D5 is turned on and the current il through transformer primary winding flows through the circulation

loop; Ls-Ds-Si.. Ls. 4) Mode 3:t

n

At timet2, the turn-off gate pulse signal (see Fig.2) is applied Ql. At this time, the switch Q, can be turned off with ZVS because the voltage VC2 was already zero during last half operation cycle and the diodes D2 Of Q2 are immediately turned on. After that, the capacitor C2 is charged up to the same voltage as dc bus line voltage E2. At this mode, the condition that the capacitor C2 is just charged up to the same voltage as ,dc bus line voltage E2 is can be estimated by eq. (3). 1/ 1 \(1/2)CE2 = (1/2) Ls (i1)2 (3) However, as described after in mode 6, circuit parameters should be designed to meet the condition of (1/2)CE2 . (J/2)L (i,/ in order to achieve ZVS commutation at turn-on transition of Q4. o 4 ||1-1 $TMode Under a condition of (1/2)CE2 < (1/2)L(4,1)2, after the voltage vc2reaches the dc bus line voltage E2, the voltage vc2 across the snubber capacitor C2 is clamped to dc bus line voltage E2 because the diode D4 of Q4 is turned on and the Lfl

|20p]

~ ~ ~ ~ ~ Ratio~ ~ ~ ~ofTurHighns Frequency N::N| 411 Load Current ~~~~~~~~~~~~~~~~~Maximiun

~~~~~~~~~~~Remarks

SI-S2

0

Io

ISiM150GBI28D

c 0 9[] 400[A]

~~~~~~~~12IGBTs IDI-D2 |Vces-l200Vjc=l 50A(Tc5251C) Diodes CMI 5ODY-12NF S3-S4 50A(Tc=250C) |D3-D4 |Vces5600V,1c

116

advantages as for the power conversion efficiency and power density as compared with the conventional hard switching inverter type dc-dc power converter. In case the switching frequency is designed for 40 kHz, the total power loss for the switches in newly-developed dc-dc power converter circuit is 445W and that of the conventional hard-switching PWM inverter is 865W. Furthermore, the snubber circuit is necessarily for the conventional hard switching PWM dc-dc power converter circuit. Therefore, the total power loss for conventional hard switching converter circuit including the power loss of snubber circuit is estimated as about 1370W. This loss is three times more than the total i-~~~~~~~~~~~~~~power loss of newly-developed converter circuit.

Fig. 6 Whole appearance of stick arc welding power supply using newly-developed soft switching dc-dc power converter.

Q1, Q2 ClO.047jF x5

D5

Q

(a) Turn-on switching waveforms for Ql, Q3 _

C l

~~~~~~50A/div

_

OA _-1

-

'\

y

-

Heatsink

C2~O.O47 F x 5

C2=O.047,u x5S

24

.Qt-

Fig. 7 Assembled component appearance in high frequency transformer primary side circuit.

The switching operating waveforms for voltage and current when the switch Q, is turned on and turned off are shown in Fig. 8 (a) and (b). Observing these waveforms, the switch Q, is turned on with ZCS and is turned off with ZVS. The switching waveforms for voltage and current when the switch Q3 is turned on and turned off are shown respectively in Fig 8. (a) and (c). Observing the operating waveforms, the switch Q3 is turned on with ZVS/ZCS and is turned off with ZVS. However, at the turn-off transition for Q, and Q3, some power loss still exists due to tail current characteristic of IGBTs.

C. Comparative Results of Power Los Analysis In power loss analysis and evaluations shown in Fig. 9, the total power loss of all the switches including Q3 and Q4 in

newly-developed dc-dc power converter circuit is compared with that of all the switches in conventional hard switching PWM inverter type. When the switching frequency is 10 kHz, the total power losses for both inverter type dc-dc power converter circuits are almost equal each other. And, the switching frequency of high frequency inverter power stage using IGBTs is designed for more than about 10 kHz, the more the switching frequency of inverter increases, the more this newly-developed dc-dc power converter circuit has remarkable

-

Qj

(b) Turn-off switching waveforms for Q,

C4

B. Measured Voltage and Current Switching Waveforms

f

100V/div

Voltage (Q3)

OV _ ~~~ Vultagt (Q,)ae

Heat sink

_

_

_

OA_

lOOV/div() ov_

- - -

-

200ns/div

(c) Turn-off switching waveforms for Q3 I I I Current (Q3) _ 50A/div

OA . - = = = -

..

_ OV

...Voltage (Q3) L i

IOOV/div

_ Onsdiv Fig. 8 Measured switching voltage and current waveforms for active power switches Q, and Q3

117

REFERENCES Conventional Hard Switching PWM Scheme with RC Snubber Snubber Capacitance: 0.01pF Snubber Resistance lo0

2500 2000

,>-

*!500

[1] S. Hamada, M. Nakaoka, "Saturable Inductor-Assisted ZVS-PWM Full-Bridge High-Frequency Link DC-DC Power Converter Operating and Conduction Losses", Proceedings of IEE-UK Intemational Conference on Power Electronics and Variable-Speed Drives,

Conventional

pp.483-488, October, 1994,

[2) 0. D .Patterson and D. M. Divan, "Pseudo-Resonant Full Bridge DC/DC Converter", Records of IEEE-PESC, pp.424-430, June,1987 [3] M. Michihira, M. Nakaoka, "A Novel Quasi-Resonant DC-DC Converter

Hard Switching

/PWM Scheme

using Phase-Shifted Modulation in Secondary-Side of High-Frequency

100C-Transformer",

low

& io

000 o

_

[4] M. Michihira, T. Funaki, M. Nakaoka, K. Matsu-ura, "A Novel

quasi-resonant DC-DC converter using phase-shift PWM control at secondary side of high-frequency transformer", Proceedings of Japan Society Power Electronics, Vol.21, No2, pp78-87, 1996. [5] S. Moisseev, S. Hamada, M. Nakaoka, "Novel Soft-Switching Phase-Shift PWM DC-DC Converter", Proceedings of Japan Society

~

> ewly developed Soft Switching PWM Scheme _

Records of IEEE-PELS Power Electronics Specialists

Conference, Vol. 1, pplO0-105, June, 1996

~

so 40 s0 20 Switching Frequency (kHz) Fig. 9 Comparative power loss analysis results between newly-developed soft switching PWM and conventional hard switching PWM dc-dc power converters.

0

Power Electronics, Vol.28, pp107-116, 2003. [6] K. Morimoto, T. Doi, H. Manabe, M, Nakaoka, H.W. Lee, "Advanced High Power DC-DC Converter using Novel Type Full-Bridge Soft-Switching PWM Inverter with High Frequency Transformer Link for Arc Welding Application", Proceedings of ICPE, pp. II191- H1197,

V. CONCLUSIONS In this paper, the novel circuit topology of half-bridge soft sicigPWM dc-dc power power converter converter with a a high frequency switching PWM dc-dc link was presented. The operating principle and switching pattern of the half-bridge soft switc,hing PWM dc-dc power converter described for 40 kHz, 36V, 400A output are illustrated and discussed for low voltage and large current output applications. The power loss analysis of the proposed soft switching power converter was discussed and evaluated as compared with hard switching PWM dc-dc power converter with a high frequency link. The practical effectiveness of the proposed power converter operation under soft switching proposed dc-dc PWM scheme was actually proved from a practical point of view and the high efficiency and power density of this converter could be achieved on the basis of experimental results for Stick arc welder. newly-developed Features ofsoft Features of newly-developed half-bridge switchingg b sw circuit are summarized as follows; 1) Under the simple circuit which has two additional semiconductor switching devices and two passive components to the typical half-bridge inverter, all the active switching devices achieve ZVS turn-off or ZCS turn-on commutation. When the switching frequency of high frequency inverter power stage using IGBTs is selected more than about 10 kHz, the more the switching frequency of inverter increases, the more this proposed dc-dc converter has remarkable advantage as for the power conversion efficiency and power density as compared with the conventional hard switching inverter type dc-dc power converter. 2) The control circuit for newly-developed circuit can be made easily by just modifying the conventional PWM implement signal circuit using common PWM control IC

October, 2004.

[7] K. Morimoto, T. Doi, H. Manabe, M. Nakaoka, N.A. Ahmed, H.W. Lee,

E. Hiraki, T. Ahmed, "Next Generation High Efficiency High Power Active Switch DC-DC Converter Snubbingwith Capacitor incorporating PWM andInverter Full-Bridge High Assisted Soft-Switching Frequency Transformer for Large Current Output", Proceedings of APEC, ppl549-1555, March, 2005 [8] K. Morimoto, T. Doi, H. Manabe, N.A. Ahmed, H.W. Lee, M. Nakaoka, T. Ahmed, "A Novel High-Frequency Transformer Linked Pulse Modulation DC-DC Power Supply for Arc Soft-Switching of PCIM China, pp 43-48, March, 2005 Proceedings Welder", [9] K. Morimoto, T. Doi, H. Manabe, T. Ahmed, E. Hiraki, N.A. Ahmed, H.W. Lee, M. Nakaoka, "Advanced High Power DC-DC Converter using

DC Bus Line Switch-Assisted Full-Bridge Soft-Switching PWM Inverter and Large with High Output FrequencyApplication", Transformer Link for Low Voltage of IPEC-Niigata, Proceedings ~~~~~~~~~~~~~~~~~Current pplS61-1568, April, 2005 [10] K.Morimoto, T. Doi, H. Manabe, T. Ahmed, N.A. Ahmed, H.W Lee, M.

(lgPC494).

3) The downsizing and light weighted welding power supply using this newly-developed soft switching dc-dc power converter circuit have been developed and put into the practical market already.

118

Nakaoka, "Selective Dual Utility AC Voltage Link Soft-Switching PWM

Controlled DC-DC Power Converter with High Frequency Transformer

.for 36V-350A DC Loads" Proceeding of IEEE-PESC (Power Electronics Specialist Conference), 2005, ppl592-1958, June, 2005