An Improved ZVT–ZCT PWM DC–DC Boost Converter With Increased Efficiency

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An Improved ZVT-ZCT PWM DC-DC

Boost Converter with Increased Efficiency

Burak Akın

Yildiz Technical University, Electrical and Electronics Engineering Faculty

Electrical Engineering Department, Davutpasa, Istanbul, 34220, TURKEY

Voice: 90 212-383-5841, Fax: 90 212-383-5858

E-mail: [email protected]

ABSTRACT: A new active snubber cell is proposed for DC-DC boost converter. Zero

Voltage Transition (ZVT) turn on and Zero Current Transition (ZCT) turn off is provided

by this active snubber cell. There is no extra current or voltage stresses on the main switch.

Also, Zero Current Switching (ZCS) turn on ZCT turn off is provided for the auxiliary

switch. Although there is no extra voltage stress on the auxiliary switch, a current stress is

present. However, auxiliary switch current stress is decreased by coupling inductance. The

coupling inductance transfers the part of the current stress to the output load according to

the transform ratio. In here, ZVT-ZCT PWM DC-DC boost converter steady state analysis

is proposed for one switching cycle. Experimental application and theoretical analysis are

proved by 300 W prototype with 100 kHz switching frequency. As a result, improved ZVT-

ZCT PWM boost converter is reached 98.7% total efficiency at full load with lowered

current stress.

Key Words: Active snubber, ZCS, ZCT, ZVS and ZVT.

I. INTRODUCTION

Nearly all electronic goods require DC power to run and it is easy to produce from AC-DC

converters. However, after that process another DC-DC converter is required for fast and easy

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control with high reliability. Fast control needs high switching frequency for the converter.

High switching frequency also causes electromagnetic interference (EMI) and extra switching

losses [1]. Normally current and voltage waveforms overlap in every switching action which

is called hard switching. Addition to overlap power loss at hard switching, reverse recovery

loss of diodes and parasitic capacitance discharge loss of the main switch is taken into account

for general power loss in switching process. Nowadays, to overcome these drawbacks, soft

switching techniques are used. Soft switching techniques provide high efficiency due to

lowered or destroyed current or voltage stresses [1-17].

There are mainly four soft switching techniques which are zero current transition (ZCT), zero

voltage transition (ZVT), zero current switching (ZCS) and zero voltage switching (ZVS). For

ZCT and ZVT techniques power loss can be gained back again, however for ZCS and ZVS

techniques only power loss can be lowered [6-8, 13, 15-17].

The proposed converter in [8], main switch ZVT turn on and ZCT turn off , auxiliary switch

ZCS turn on and ZCT turn off are provided. Although ZVT-ZCT soft switching tecniques

improve the efficiency, the current stress on the main switch is two times more than the input

current. Nevertheless, extra current stress is present on the auxiliary switch. Because, these

extra current stresses affects converter reliability and performance, the system efficiency is

98,3% at full load.

The proposed converter in [13], ZVT isolated boost converter is explained, however only

ZVT turn on of active switches are achieved. Although ZVS soft switchings is provided for

main and clamp switches, diodes power loss is present by the reverse recovery problem. The



main switch and the auxiliary switch extra current stresses are still present for the proposed

converter. So, the efficiency of the proposed converter is around 96% at full load.

The proposed system in [15], ZCS PWM DC-DC boost converter provides ZCS turn on and

ZCT turn off for the main switch. However there is an extra current stress on the main switch

due to resonance. The auxiliary switch has no advantage of soft switching. So hard switching

apply to the auxiliary switch. Clamping diode assisted ZCS PWM conveter has 98.4% total

efficiency at full load.

The proposed converter in [16], capacitor cell assisted soft switching PWM DC-DC converter

is explained. The main switch ZCS turn on and ZVS turn off processes are achieved, however

extra current and voltage stresses are present both for the main and the auxilairy switch.

Additionally, high circulating current is present for the main and the auxiliary switches. The

efficiency of the converter is about 96%.

The proposed system in [17], the main switch ZVT turn on and ZCT turn off are provided.

However, for the auxiliary switch ZCS turn on and nearly ZCS turn off are provided. IGBT is

used as the main switch and MOSFET is used as the auxiliary switch. Although there is no

extra current stress on the main switch and lowered current stress on auxilary switch, the

system efficiency is 98%. On the other hand, the proposed system is realized as AC-DC PFC

converter which is controlled to get unity power factor at the AC mains.

The aim of this study is to improve PWM DC-DC boost converter topology with ZVT-ZCT

soft switching techniques. As presented in here, the published converters have extra current

and/or voltage stresses even if they use soft switching techniques. So, a new active snubber



cell is proposed to solve these problems. In the proposed active cell, main switch ZVT turn on

and ZCT turn off, auxiliary switch ZCS turn on and ZCT turn off are provided respectively.

The main switch extra current and voltage stresses are eliminated. The auxiliary switch

voltage stress is eliminated and current stress is lowered by the coupling inductances in the

snubber cell.

The current stress in the auxiliary switch is lowered by the coupling effect. Depend on

coupling inductance transform ratio, current stress is transferred to the output load. So,

switching power loss is lowered and efficiency is improved. Also, by adding the D2 diode

serially to the auxiliary switch path, incoming current stresses from the resonant circuit is

prevented for to the main switch. As a result, the proposed converter system has 98.7%

efficiency at full load. To verify this theoretical analysis, 300 W with 100 kHz ZVT-ZCT

PWM DC-DC boost converter is realized.

When the proposed converter and other snubber cell topologies [8, 13, 15, 16, and 17] are

compared in terms of the number of components, commutation and switching operations the

advantages of the proposed snubber cell can be explained as fallows. Although, they have

similar commutation and control techniques, the proposed converter has coupling inductance

and D2 diode different from [8]. As a result, these components provide better efficiency

without any extra current stress on the main switch. There are extra 2 switches, 2 coupling

inductances and 2 resonance capacitor with reduced diodes in [13]. This converter has

complex control and low efficiency. Furthermore, only ZVT turn on is provided for the main

switches. There are less passive components in [15] and [16] compared to the proposed

converter, although these topologies use resonance, ZCS turn on, ZCT turn off and ZCS turn

on and ZVS turn off are provided for the main switch respectively. There are extra current



stresses on the main switches and efficiency values are low against to the proposed converter.

Although there are same numbers of components in the snubber cell of [17], this topology is

controlled for PFC application at the AC mains. Auxiliary switch is replaced with IGBT in the

proposed converter with resonance PWM control for higher efficiency value.

II. THE OPERATION PRINCIPLE FOR THE PROPOSED CONVERTER

The proposed converter topology is shown in Figure 1. In here, output load R, output

capacitor Co, output voltage Vo, DC source Vi, boost inductance LF, the main switch S1, the

auxiliary switch S2 and the boost diode DF are shown respectively. The S1 IGBT has main

switch, antiparallel diode DS1 and equivalent parasitic capacitor of the main switch CS. Same

as the main switch, the S2 IGBT has auxiliary switch and antiparallel diode DS2. Resonance

inductances LR1 and LR2, snubber capacitor CR, and auxiliary diodes D1, D2, D3 and D4 are

shown in the active snubber cell. The input and the output leakage inductances Lil and Lol are

part of the coupling transformer.

A) SWITCHING STEPS

In one switching cycle there are twelve steps for the proposed converter. From Figure 2 (a)-

(l), equivalent circuits of the proposed converter are shown. Also in Figure 3, proposed

converter current and voltage waveforms are illustrated for one switching cycle.

Step 1: 10 ttt - Figure 2 (a)

At the beginning of this step, all switches are turned off. So t=t0, iS1=0, iS2=0, iDF=Ii, iLR1=0,

iLR2=0 and vCR=0 are valid. The PWM control is off state so, DF conducts input current.

Before S1, S2 switching signal is applied to start resonance in snubber cell. While IDF



decreases, IS2 increases due to the resonance between CR-LR1-LR2. Because of LR2, D1, D2 and

S2 conducts current with ZCS. In here,

))(sin()( 0011 ttL

Vtt

L

Vii e

Se

o

S

o

DLR

(1)

))tt(sin(LL

V)tt(

L

Vii 0e

2RSe

o0

S

o2S2LR

(2)

)))tt(cos(1(L

LVv 0e

S

1RoCR (3)

olm

mLRDLol

LaL

aLiii

224

(4)

olm

olmilR

LaL

LaLLL

2

2

2

(5)

21 RRS LLL (6)

21

21

RR

RR

eLL

LLL

(7)

Re

eCL

1 (8)

are valid. The coupling inductance transform ratio (a) is formulated as a= N1 N2 . Serial

equivalent inductance Ls and parallel equivalent inductance Le are defined in (6) and (7). At

t=t1, IS2 reaches to Ii and then, ZCS and ZVS turn off is provided for DF because of IDF falls to

zero.

Step 2: 21 ttt - Figure2 (b)

At t=t1, a resonance occurs between CS-LR1-LR2-CR due to CS discharge energy. The CS

transfers its energy to LR2 and LR2 transfers the part of energy to the output load. For this step,



CR1LR

1R Vdt

diL (9)

CRCS2LR

2R VVdt

diL (10)

12 LRLRCR

R iidt

dvC (11)

)1(222

olm

m

LRiLolLRi

CS

SLaL

aLiIiiI

dt

dvC

(12)

equations are valid.When VCS is zero, ZVS turn on is provided for DS1 and also D4 is turned

off.

Step 3: 42 ttt - Figure2 (c)

At t=t2 DS1 is turned on, so it conducts resonant current between LR1-LR2-CR. In this step

related formulas are valid. The resonant circuit equivalent impedance is represented as Ze.

)))tt(cos(1(IL

L)))tt(cos(1(I

L

Li 2e12LR

2R

e

2e22LR

1R

e

1LR

))tt(sin(L

V))tt(cos(I 2e

1Re

2CR

2e12LR

(13)

)))tt(cos(1(IL

L)))tt(cos(1(I

L

Li 2e12LR

2R

e

2e22LR

1R

e

2LR

))tt(sin(L

V))tt(cos(I 2e

2Re

2CR

2e22LR

(14)

)))tt(sin()II(Z))tt(cos(Vv 2e12LR22LRe2e2CRCR (15)

R

ee

C

LZ (16)



Re

eCL

1 (17)

The difference between iLR2 and Ii passes through DS1. So it is time to ZVT turn on for S1.

When iLR2 is equal to Ii, ZCS turn off is provided for DS1. While IS1 rises due to PWM on time

iLR2 decreases. Ds2 is turned on during the reverse recovery time of D2 when iLR2 reaches

zero. So, now S2 switching signal can be cut. As a result, ZCT turn off is provided for S2.

Step 4: 54 ttt - Figure2 (d)

For this interval iS1=Ii, iS2=0, iDF=0, iLR1=ILR14, iLR2=0, vCR=VCR4 and vCS=0 are valid. While Ii

passes through S1, a resonant starts between LR1-CR-D1. In here,

))tt(sin(Z

V))tt(cos(Ii 41

1

4CR

4141LR1LR (18)

))tt(sin(IZ))tt(cos(Vv 4114LR1414CRCR (19)

R

R

C

LZ 1

1 (20)

RR CL 1

1

1 (21)

equations are represented. By the resonance, ILR1 charges CR. VCRmax is presented in (22).

2

14LR1

2

4CRmaxCR )IZ(VV (22)

Step 5: 65 ttt - Figure2 (e)



At this step, Ii passes through S1 and snubber circuit is deactivated. As a DC-DC boost

converter main inductance charges with Ii. PWM control lets the converter work as

conventional DC-DC boost converter. For this interval,

iS1=Ii (23)

equation is defined.

Step 6: 86 ttt - Figure2 (f)

For this step, iS1=Ii, iS2=0, iDF=0, iLR1=0, iLR2=0, vCR=VCR6=VCRmax and vCS=0 are valid. Before

to turn off S1 with ZCT, S2 must be turned on. By applying switching signal to S2, LR2

resonate with CR. In this step,

))(sin( 62

2

max

22 ttZ

Vii CRSLR (24)

))(cos( 62max ttVv CRCR (25)

R

R

C

LZ

2

2 (26)

RR CL 2

2

1 (27)

are obtained. Due to LR2, ZCS turn on is provided for S2. By the resonance iS2 increases and

iS1 decreases. ZCS turn on is provided for DS1 when iS1 is zero. So, ZCT turn off is provided

for S1. After cutting S1 switching signal, the difference between iLR2 and Ii passes through DS1.

The maximum iLR2 is defined below.

2

max

max2Z

VI CR

LR (28)

Step 7: 98 ttt - Figure2 (g)



Here, iS1=0, iS2=ILR2max, iDF=0, iLR1=0, iLR2=ILR2max, vCR=0 and vCS=0 assumptions are initial

values. So, D1 is turned on, while vCR becomes positive. As a result, CR-LR2-LR1 conduct a

new resoance current. Below equaitions are defined for this step.

)))(cos(1( 8max2

1

1 ttIL

Li eLR

R

eLR (29)

)))(cos(1()))(cos(1( 8max28max2

1

2 ttIttIL

Li eLReLR

R

eLR (30)

)))(sin( 8

max2 ttC

Iv e

Re

LRCR

(31)

milRS LLLL 1 (32)

milR

milR

eLLL

LLLL

1

1 )( (33)

Re

eCL

1 (34)

In auxiliary switch path, iLR2 decreases to input current and then iDS1=0 is valid with ZCS turn

off.

Step 8: 109 ttt - Figure2 (h)

For this interval, iS1=0, iS2=Ii, iDF=0, iLR1=ILR19, iLR2=Ii, vCR=VCR9 and vCS=0 assumptions are

true. Now, another resonance starts through CS-CR-LR1-LR2 with input current. Here,

CRLR

R vdt

diL 1

1 (35)

CRCS2LR

2R vvdt

diL (36)

12 LRLRCR

R iidt

dvC (37)



2LRiCS

S iIdt

dvC (38)

are defined. By the time iLR2=0, Ds2 is turned on during the reverse recovery time of D2, so

now S2 switching signal can be cancelled. Hence, ZCT turn off process is completed for S2.

Step 9: 1110 ttt - Figure2 (i)

In this step, iS1=0, iS2=0, iDF=0, iLR1=ILR110, iLR2=0, vCR=VCR10 and vCS=VCS10 definitions are

accepted. From the Figure 2 (i), two closed loop are valid. While input current charges CS, a

new resonance starts between D1-LR1-CR. Below formulas are valid for this step. At the end of

this step, D3 is turned on due to the sum of vCS and vCR voltages are over output voltage.

)tt(sin(Z

V))tt(cos(Ii 101

1

10CR101110LR1LR (39)

))(sin())(cos( 101110110110 ttIZttVV LRCRCR (40)

(41)

Step 10: 1211 ttt - Figure2 (j)

For this interval, iS1=0, iS2=0, iDF=0, iLR1= ILR111, iLR2=0, vCR=VCR11 and vCS=Vo-VCR11

assumptions are true. The input current passes through CS, LR1 and CR with a new resonance.

When iLR1=0, CS and Co store all the energy in LR1. For this step below formulas are achieved.

iCR

iLRLR IttZ

VttIIi ))(sin())(cos()( 113

3

11

1131111 (42)

))(sin()())(cos( 11311311311 ttIIZttVvVv iLRCRCSoCR (43)

RS CCC 3 (44)

)tt(C

Iv 10

S

iCS



31

3

1

CLR

(45)

3

13

C

LZ R

(46)

Step 11: 1312 ttt - Figure2 (k)

In this mode, At t=t12, iS1=0, iS2=0, iDF=0, iLR1= 0, iLR2=0, vCR=VCR12 and vCS=Vo-VCR12 are

accepted. While CR is discharged, input current charges CS. In here,

)( 12

3

12 ttC

IVv i

CRCR

(47)

is valid. ZVS turn on is provided for DF due to vCR=0.

Step 12: 1413 ttt - Figure2 (l)

DF conducts input current to the output load as a part of conventional boost converter. In here,

iDF = Ii (48)

is valid. At last, one switching section is completed. A new switching section can be start with

new switching steps.

III. SOFT SWITCHING TYPES FOR POWER SWITCHES

Below explanations are made to prove soft switching types of the main and the auxiliary

switches.



1. ZVT turn on and ZCT turn off for the main switch

ZVT and ZCT soft switching processes are provided by S2. Auxiliary switch S2 is turn on and

off twice for one S1 turned on time. Before S1 switching signal, S2 turns on and so, S1 parasitic

capacitor discharges its energy to the snubber circuit. When DS1 is turned on, it is time for

ZVT turn of for S1. As long as the tZVT time, S1 switching signal can be applied. In the

proposed converter S1 turn on is provided with ZVT.

To provide ZCT turn off for S1, while S1 conducts input current, S2 switching signal is

applied to S2 to create a resonante current higher than the input current. Therefore, excessive

current forces DS1 to turn on. As long as the tZCT time, S1 switching signal can be cancelled.

For the proposed converter, S1 turn off is provided with ZCT.

2. ZCS turn on and ZCT turn off for the auxiliary switch

ZCS turn on is provided by serial inductances in the auxiliary switch path. These inductances

take control of sudden current changes for the S2. As a result for the proposed converter ZCS

turn on process is provided for S2. It can be observed that current stress on S2 is lowered by

coupling effect of the inductances. So, part of the switching power loss is gained back and

sent to output load. This action will increase converter efficiency.

Despite [17], ZCT turn off also provided for S2. For this action, S2 current is decreased to zero

with a resonance, to force DS2. While DS2 conducts reverse current, S2 switching signal can

be cancelled to provide ZCT turn off for S2. S2 fall time and Ds2 reverse recovery time must

be smaller than D2 reverse recovery time to provide perfect ZCT switching. As a result, ZCT

turn off is provided for S2 in the proposed converter.



IV. WORKING CRITERIA

The soft switching techniques are used not only for the main switch but also for the auxiliary

and other semiconductors. The new active snubber cell components are chosen in order to the

below working criteria. Further investigation can be done, however the subject of this paper

is about soft switching working principles.

1. The LR2 value can be defined as fallows to provide ZCS soft switching for the auxiliary

switch.

max2

2

irS

LR

o ItL

V (49)

2. The LR1 value is defined below to provide sufficiently high resonant current to turn on

DS1.

R1 R2L 2*L (50)

3. The main switch fall time must be smaller than ZCT time to provide perfect ZCT soft

switching conditions.

4. The chosen LR1, LR2 and CS configure CR value to provide ZCT soft switching.

5. A part of the switching power loss is gained back by the coupling inductance.

Transform ratio plays a vital role by input and output turns. It is defined as fallows to

provide efficiency improvement without any voltage stress.

1 2 1N N 1,5*N (51)



6. S2 fall time must be smaller than D2 reverse recovery time to provide perfect ZCT

switching.

V. ADVANTAGES OF THE PROPOSED CONVERTER

Although there are some ZVT-ZCT DC-DC boost converters in literature, the proposed

converter get full benefits of them. As a result, advanced soft switching techniques are used

for the proposed converter not only for lowering the current stress on power switches but also

improving the efficiency.

1. The main switch is turned on with ZVT and turned off with ZCT.

2. The auxiliary switch is turned on with ZCS and turned off with ZCT.

3. The main diode is turned on with ZVS and turned off with ZCS and ZVS.

4. The main switch extra voltage and current stress are disappeared.

5. The auxiliary switch extra voltage stress is disappeared and current stress is lowered

by the coupling inductances.

6. The main diode extra voltage and current stress is disappeared.

7. S2 switching frequency is two times of S1 switching frequency.

8. High switching frequency gives advantage of fast control and high power density with



lowered component values.

9. Although soft switched active snubber cell is used in the proposed converter, total time

interval is sufficienctly small to work as normal PWM control.

10. Except D2, SIC diodes are used in the converter to provide better reverse recovery

power loss.

11. The proposed active snubber cell can be used for higher power levels for many DC-

DC PWM converters.

VI. EXPERIMENTAL RESULTS

The proposed converter is realized for 100 kHz switching frequency at 300W output load. In

Figure 4, a prototype and in Figure 5, photograph of the proposed converter is shown

respectively. The rest of the paper is organized as follows: Vi=200V, LF=2200 µH, LR1= 4

µH, LR2= 2 µH, Lol= 3 µH, CR= 4,7 nF, Co=330 µF. Voltage, current and part numbers of the

semiconductors are shown in Table 1.

S1 and S2 switching signals, S1 soft switching waveforms, S2 soft switching waveforms, DF

soft switching waveforms, CR current and voltage waveforms, LR2 current and voltage

waveforms, LR1 current and voltage waveforms and D3 current and voltage waveforms are

shown in Figure 6 (a-i) respectively. In Figure 6 (b), ZVT turn on and ZCT turn off are

provided for the main switch at full load. In Figure 6 (c), ZCS turn on and ZCT turn off are

provided for the auxiliary switch at full load. In Figure 6 (d), ZCS turn on and ZVS turn off

are provided for the main diode at full load.



Hard and soft switching waveforms are shown in Figure 7 for the main switch. In Figure 7 (a)

and (b), current and voltage overlapping is shown for hard switching however, in Figure 7 (c)

and (d) current and voltage waveforms are shown for ZVT and ZCT soft switching. The

proposed converter total efficiency is shown in Figure 8 with efficiency curves of [8], [17]

and hard switching. The experimental prototype reaches 98.7% total efficiency at full load.

From Figure 7, efficiency improvement is verified for full load range in the literature. For

instance, theoretical and experimental explanations are carried out for ZVT-ZCT PWM DC-

DC proposed boost converter.

VII. CONCLUSIONS

The proposed ZVT-ZCT PWM DC-DC boost converter has one active snubber circuit to

provide soft switching for all semiconductors. ZVT turn on and ZCT turn off are provided for

the main switch, ZCS turn on and ZCT turn off are provided for the auxiliary switch and ZCS

turn on and ZVS turn off are provided for the main diode respectively. Also other diodes get

benefits of the resonance current due to turn on and turn off processes. A detailed steady state

analysis is explained for each switching interval.

To prove theoretical analysis, an experimental prototype is realized. While the prototype

converts 200 V to 400 V as a conventional boost converter, it provides advanced soft

switching techniques at 100 kHz for 300W output load. Serially added D2 diode prevents

reverse resonance currents to create current stress on S1. Also, the auxiliary switch current

stress is lowered by coupling inductance. This power loss is gained back by transferring it to

the output load. As a result, the converter system has 98.7% total efficiency at full load. The

efficiency improvement is achieved by ZVT-ZCT DC-DC boost converter.



REFERENCES

1. W. Huang, G. Moschopoulos, “A New Family of Zero Voltage Transition PWM

Converters With Dual Active Auxiliary Circuits” IEEE Transactions on Power Electronics,

vol. 21, pp. 370-379, March 2006

2. G. Hua, C. S. Leu, Y. Jiang, and F. C. Lee, “Novel Zero-Voltage-Transition PWM

Converters,” IEEE Transactions on Power Electronics, vol. 9, pp. 213-219, Mar. 1994.

3. G. Hua, E. X. Yang, Y. Jiang, and F. C. Lee, “Novel Zero-Current-Transition PWM

Converters,” IEEE Transactions on Power Electronics, vol. 9, pp. 601-606, Nov. 1994.

4. R. L. Lin, Y. Zhao, F.C. Lee, “Improved Soft-Switching ZVT Converters with Active

Snubber”, Applied Power Electronics Conference and Exposition IEEE, vol. 2, pp. 1063 –

1069, Feb. 1998.

5. H. Bodur and A. F. Bakan, “A New ZVT-PWM DC-DC Converter,” IEEE Transactions

on Power Electronics, vol. 17, pp. 40-47, Jan. 2002.

6. H. Bodur, and A.F. Bakan, “A New ZVT-ZCT-PWM DC-DC Converter,” IEEE

Transactions on Power Electronics, vol. 19, pp. 676-684, May. 2004.

7. A.F. Bakan, H. Bodur, and I. Aksoy, “A Novel ZVT-ZCT PWM DC-DC Converter”, 11th

Europen Conference on Power Electronics and Applications (EPE2005), Dresden, 1-8, Sept.

2005.

http://ieeexplore.ieee.org/xpl/RecentCon.jsp?punumber=5223



8. Aksoy, I.; Bodur, H.; Bakan, A.F.; , "A New ZVT-ZCT-PWM DC–DC Converter," Power

Electronics, IEEE Transactions on , vol.25, no.8, pp.2093-2105, Aug. 2010

9. P. Das, and G. Moschopoulos, “A Comparative Study of Zero-Current-Transition PWM

Converters”, IEEE Transactions on Industrial Electronics, vol.54, pp. 1319-1328, June 2007.

10. Jae-Jung Yun; Hyung-Jin Choe; Young-Ho Hwang; Yong-Kyu Park; Bongkoo Kang; ,

"Improvement of Power-Conversion Efficiency of a DC–DC Boost Converter Using a Passive

Snubber Circuit," Industrial Electronics, IEEE Transactions on , vol.59, no.4, pp.1808-1814,

April 2012.

11. Urgun, S.; , "Zero-voltage transition–zero-current transition pulsewidth modulation DC–

DC buck converter with zero-voltage switching‣zero-current switching auxiliary circuit,"

Power Electronics, IET , vol.5, no.5, pp.627-634, May 2012

12. da S Martins, M.L.; de O Stein, C.M.; Russi, J.L.; Pinheiro, J.R.; Hey, H.L.; , "Zero-

current zero-voltage transition inverters with magnetically coupled auxiliary circuits: analysis

and experimental results," Power Electronics, IET , vol.4, no.9, pp.968-978, November 2011

13. Yi Zhao; Wuhua Li; Yan Deng; Xiangning He; , "Analysis, Design, and Experimentation

of an Isolated ZVT Boost Converter With Coupled Inductors," Power Electronics, IEEE

Transactions on , vol.26, no.2, pp.541-550, Feb. 2011



14. Mohammadi, M.R.; Farzanehfard, H.; , "New Family of Zero-Voltage-Transition PWM

Bidirectional Converters With Coupled Inductors," Industrial Electronics, IEEE Transactions

on , vol.59, no.2, pp.912-919, Feb. 2012

15. Mishima, T.; Nakaoka, M.; , "A Practical ZCS-PWM Boost DC-DC Converter With

Clamping Diode-Assisted Active Edge-Resonant Cell and Its Extended Topologies,"

Industrial Electronics, IEEE Transactions on , vol.60, no.6, pp.2225-2236, June 2013

16. Mishima, T.; Takeuchi, Y.; Nakaoka, M.; , "Analysis, Design, and Performance

Evaluations of an Edge-Resonant Switched Capacitor Cell-Assisted Soft-Switching PWM

Boost DC–DC Converter and Its Interleaved Topology," Power Electronics, IEEE

Transactions on , vol.28, no.7, pp.3363-3378, July 2013

17. Akın, B.; Bodur, H.; , "A New Single-Phase Soft-Switching Power Factor Correction

Converter," Power Electronics, IEEE Transactions on , vol.26, no.2, pp.436-443, Feb. 2011



FIGURES

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1

Lm

CR

D4

+

Vo

-

Io

N2

Lil

Ii

Lol

+

vCR

-

N1

LR2+

Vi

-

Co

iS1

iS2

iLR2

iLR1

IDF

+

vCs

-

DC

Snubber

Circuit

DS2

D2

Figure 1. The circuit scheme of the proposed ZVT-ZCT PWM converter.



R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( a ) t0

< t < t1

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( b ) t1

< t < t2

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( c ) t2

< t < t4

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( d ) t4

< t < t5

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( e ) t5

< t < t6

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( f ) t6

< t < t8

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( g ) t8

< t < t9

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( h ) t9

< t < t10

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( i ) t10

< t < t11

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( j ) t11

< t < t12

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( k ) t12

< t < t13

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

Co

iS1

iS2

iLR2

iLR1

IDF

Vi

DS2

D2

Lil

( l ) t13

< t < t14

Figure 2. Equivalent circuit schemes of the operation modes



IrrIrr

VD2VD2

ID2

ID4

IDS1IDS1

tZCTtZVT

VGE-S1

VGE-S2

İS1

İDF

İLR2,D2,S2

İLR1,D1

İCR

VS1

VDF

VCR

VS2

t0 t1 t2 t6t3 t5t4 t9t8 t10t7 t12t11

VLR2

VLR1

t13 t14=t0

Figure 3. Key waveforms concerning the operation stages in the proposed converter.



2200 µH

4 µH

2 µH

4.7 nF

330 µF

530 W

3 µH

R

LF

S1

S2

DS1 CS

DF

D1

D3

LR1CR

D4

Io

N2

Ii

Lol

N1

LR2+

200 V

-

Co

iS1

iS2

iLR2

iLR1

IDF

DC

DS2

D2

+

400 V

-

Figure 4. The prototype circuit scheme of the proposed converter.

Figure 5. The photograph of the experimental circuit.



(a) (b)

(c) (d)

(e) (f)

(g) (h)

Figure 6. Some oscillograms of the converter. a) Control signals of 1S and

2S (5 V/div and 2

s/div) b) Voltage and current of 1S , c) Voltage and current of 2S and d) Voltage and

current of FD (100 V/div, 2 A/div and 1 s/div). e) Voltage and current of RC , f)

Voltage and current of 2RL and g) Voltage and current of

1RL (50 V/div, 2 A/div and 5

s/div). h) Voltage and current of 3D (100 V/div, 2 A/div and 5 s/div).



(a) (b)

(c) (d)

Figure 7. Main switch hard and soft switching waveforms a)Hard turn on b) Hard turn off (100 V/div,

5 A/div and 0.1 s/div) c) Soft turn on (ZVT) d) Soft turn off (ZCT) (100 V/div, 2 A/div and 0.1 s/div)



Figure 8. Overall efficiency curves of the proposed and referred SS with the HS converters

comparatively.

Table I. Some significant values of the semiconductor devices used in the prototype circuit.

Semiconductor

Device Part Number

V

( V )

I

( A )

tr

( ns )

tf

( ns )

trr

( ns )

S1 S1

IXGR50N60C2D1 600 40 45 40 -

Ds1 600 40 - - 140

S2 S2 SGP23N60UF 600 23 27 60 -

Ds2 SDT08S60 600 8 10

DF,D1,D3, D4 SDT08S60 600 8 - - 10

D2 MUR860 600 8 - - 60

Documents

An Improved ZVT–ZCT PWM DC–DC Boost Converter With Increased Efficiency