2-Phase Series Capacitor Synchronous Rectifierin Active Clamp Forward Converter+

Katsuhiro Hata1, Sadanori Suzuki2, Kenichi Watanabe2, Kenichi Nagayoshi2, and Makoto Takamiya1
1The University of Tokyo, Tokyo, Japan
2Toyota Industries Corporation, Aichi, Japan
E-mail: khata@iis.u-tokyo.ac.jp
Abstract— A 2-phase series capacitor synchronous rectifier
LIL
IO(SC-SR) in active clamp forward (ACF) converters is proposed
CClampto solve the inductor cooling problems caused by the recent
VClamp+nPnS
trend of increasing the output current. The proposed 2-phase
QP2
V
IN
SC-SR can achieve the interleaved operation by adding only one
+
+
+
VO
CO
RO
flying capacitor to the 2-parallel conventional SRs without
increasing the number of the primary circuit elements and
QP1
QS1
QS2
transformer. Furthermore, the proposed 2-phase SC-SR canachieve the automatic inductor current balancing, which helps
distribute the heat evenly in the two inductors. In theFig. 1. Active clamp forward converter with conventional synchronous
measurement at 140 V-to-5 V conversion, the peak efficiency ofrectifier.
the ACF converters with the proposed 2-phase SC-SR andconventional SR was 90.3 % and 85.9 % at 28 AOUT,
La I
Ct
IL
IO
La
respectively, resulting in the improvement in efficiency by
CClamp
4.4 %. In addition, the interleaved operation of the proposed 2VCt
VClampphase SC-SR reduced the output current ripple from 10.8 A to
+
nP
nS
QS2a
Q
P2
VIN
Lb I
6.4 A compared to the conventional SR at 40 AOUT. The current
Lb
+
+
+
VO
CO
RO
imbalance between the two output inductors of the proposed 2Q
S1bphase SC-SR was less than 10% under heavy load even without
QP1
QS1a
any control or compensation, demonstrating the practicability
QS2bof the proposed 2-phase SC-SR in ACF converters.
Keywords— Active clamp forward converter, Synchronousrectifier, Series capacitor converter, current sharing.

I. INTRODUCTION
Active clamp forward (ACF) converters [1–2] are suitable
for a high step-down conversion in applications such as
EV/HEV, servers, and data centers [3–5]. The trend ofincreasing the output current in recent years, however, causes
problems due to the increased heat generation in the output
inductor of the ACF converter with the conventional
synchronous rectifier (SR), which is shown in Fig. 1. To
suppress the heat generated in the inductor, it is conceivable
to connect the converters in parallel and perform theinterleaved operation [6–8]. Alternatively, to reduce theincrease in the number of elements including transformers,
paralleling only the secondary circuit is also possible, but thisway cannot achieve interleaving because the transformer isshared and the secondary circuit operation depends on thesecondary current of the transformer. In addition, paralleling
two inductors without interleaving increases the output
current and voltage ripple due to the reduced equivalent
inductance. In order to prevent this, it is necessary to increase
the inductor size.

2-phase series capacitor synchronous rectifierFig. 2. Active clamp forward converter with proposed 2-phase seriescapacitor synchronous rectifier (SC-SR).

II. PROPOSED 2-PHASE SERIES CAPACITOR SYNCHRONOUS
RECTIFIER (SC-SR)
A. Circuit operation
Fig. 2 shows the ACF converter with the proposed 2-phase
SC-SR, which consists of 4 switches, 2 inductors, and 1 flying
capacitor. The phase A consists of QS1a and QS2a, where QS1a
is operated synchronously with QP1, and QS2a is alternately
turned on and off with QS1a in continuous current mode. The
phase B is composed of QS1b and QS2b, where QS1b is operated
with 180° phase difference from QS1a for interleaving and QS2b
are also alternately turned on and off QS1b in continuous
current mode. The duty cycles Da and Db are defined as theon-time ratios of QS1a and QS1b in each phase and this paper
assumes that Da and Db do not exceed 50 %.
Focusing on the circuit operation in a steady state, the main
circuit states and ideal waveforms of the proposed 2-phase
SC-SR are shown in Figs. 3 and 4. During state 1, QS1a in thephase A is turned on synchronously with QP1, where the seriescapacitor Ct is connected in series with La and the transformer
supplies the current ILa, which charges Ct. Also, QS2b is on in
the phase B, so ILb freewheels through QS2b. During state 2,
QS1a is turned off synchronously with QP1 and the transformer
stops supplying the current, so the current path of ILa changes
from QS1a to QS2a. Since ILb continues to freewheel throughQS2b, Ct is neither charged nor discharged, keeping the voltage
VCt constant. During state 3, QS1b turns on instead of QS2b in
the phase B, where Ct is connected in series with Lb andsupplies the current ILb, which discharges Ct. Also, QS2a is onin the phase A and ILa continues to flow through QS2a. Finally,

To solve these problems, this paper proposes a 2-phaseseries capacitor synchronous rectifier (SC-SR), which can be
regarded as applying a circuit topology of non-isolated 2phase series capacitor (SC) buck converters with two output
inductors [9–13] to the synchronous rectifier in isolated DCDC converters. Similar to the non-isolated SC buck converter,
the proposed SC-SR can achieve the interleaved operation andcurrent balancing of the two output inductors in the isolated
DC-DC converter, distributing the heat evenly to the two
inductors. In this paper, the operating principle of the
proposed 2-phase SC-SR in an ACF converter is presented
and the practical feasibility of the proposed 2-phase SC-SR isdemonstrated by experiments.

978-1-6654-7539-6/23/$31.00 ©2023 IEEE

906

nS
V
nP IN

+

Ct

VCt

+

La

ILa

Lb

ILb

IL

IO

CO

+

Φ1 Φ2 Φ3 Φ4 Φ1 Φ2 Φ3 Φ4

QP1
QS1a

0 DaTS (1-Da)TS

+

VO

RO

DbTS (1-Db)TS0(a) State 1 (Φ1)

nS
VnP Clamp

+

+

Ct

VCt

La

ILa

Lb

ILb

t

TS /2

QS1b

t
nS
V
+ VCt
nP Clamp

VDS,S1a

IL

CO

IO

+

RO

0

t
nS
V -V
nP IN Ct

VDS,S2a

+

VO

0

t
nS
nP VIN

VDS,S1b(b) States 2 and 4 (Φ2 and Φ4)nS
VnP Clamp

+

+

Ct

VCt

La

ILa

Lb

ILb

VCt

0

IL

IO

t
nS
nP VClamp

VDS,S2b
0

CO

+

RO

+

ΔILa

ILa

VO

a

ΔILb

ILb

Fig. 3. Main circuit states in the proposed 2-phase SC-SR.

ΔIL

0 VO = VCt Db

IL = IO

nS

Da

nS

DaDb

VCt = n D + D VIN
Pabt

VO = n D + D VIN
P
a
b

0

t

Fig. 4. Idealized waveforms of the proposed 2-phase SC-SR.

Voltage conversion ratio M= (VCt − VO ) DbTS + ( 0 − VO )(1 − Db ) TS

b

t

t

0
VO

n

=  S VIN − VCt − VO  DaTS + ( 0 − VO )(1 − Da ) TS
n
 P

n

 VO =  S VIN − VCt  Dan
 P

0 = VLb

ΔVCt

VCt

0 = VLaDaa

IL

B. Voltage conversion ratio
Based on the voltage-second balance in La and Lb, theoutput voltage VO of the ACF converter with the proposed 2phase SC-SR is given as follows:bt
ILb = D + D IO

0during state 4, QS2b turns on instead of QS1b, so ILa and ILb
freewheel through QS2a and QS2b as in state 2.

Db

ILa = D + D IO

0(c) State 3 (Φ3)

t

(1)

(2)

where VIN, <VLa>, <VLb>, nP, nS, and TS are the input voltage,
the average induced voltage of La, the average induced voltageof Lb, the number of transformer primary winding turns, thenumber of transformer secondary winding turns, and theswitching period, respectively.

nS Da
VIN
nP Da + Db

(3)

VO =

nS Da Db
VIN
nP Da + Db

(4)

Prop. (np:ns=4:1)
nP:nS = 4:1

Prop. (np:ns=3:1)
nP:nS = 3:1
Prop. (np:ns=2:1)
nP:nS = 2:1

0.1

Conv. (np:ns=4:1)
nP:nS = 4:1

0.05

0
0

0.1

0.2
0.3
Duty cycle D

0.4

0.5

Fig. 5. Voltage conversion ratio M vs. duty cycle D (= Da = Db).

Since VCt and VO are derived according to (1) and (2), thevoltage conversion ratio M of the ACF converter with theproposed 2-phase SC-SR is obtained as follows:

VCt =

0.15

M=

VO nS Da Db.
=
VIN nP Da + Db

(5)Fig. 5 shows M as functions of D in the ACF converterwith the proposed 2-phase SC-SR and conventional SR, where
D = Da = Db is assumed for simplicity. The proposed 2-phase
SC-SR achieve half the step-down ratio with the same nP, nS,
and D as the conventional SR. In other words, the proposed 2-

907

TABLE I.

COMPARISON OF NUMBER OF COMPONENTS AND FEATURES IN CIRCUIT CONFIGURATIONS.

SwitchnumberTransformer
numberInductor
numberFlying capacitor
numberInductor current

Current balancing

Interleaving

ACF converter with SR(Fig. 1)

Pri.: 2
Sec.: 2

1

1

-

IO

-

-

2-parallel ACF converters
with SR (Fig. 6)
ACF converter with
2-parallel SRs (Fig. 7)
ACF converter withproposed 2-phase SC-SR(Fig. 2)

Pri.: 4Sec.: 4Pri.: 2
Sec.: 42

2-

IO/2 (If ideal)

Yes(Control required)

Yes

1

2

-

IO/2 (If ideal)

No

No

1

2

1

IO/2

Yes
(Automatic)

Yes

Pri.: 2
Sec.: 4phase SC-SR can reduce the number of transformer primarywinding turns to half that of the conventional SR in order toachieve the same step-down ratio, contributing to a reductionin the copper loss due to the transformer primary windings.

La I
La
Vclamp,a
VIN

QP2a

Vclamp,b
QP2b

+

RO

+

VO

QS2a

Cclamp,b
nP

nS

QS1b

QP1b

QS2b

Fig. 6. 2-parallel active clamp forward converters with conventional
synchronous rectifier.

VIN

(7)

QP2

CClamp

+

nP

La

ILa

Lb

ILb

IO

QS1a
nS

QS2a

+

CO

+

RO

+

VO

QS1b

QP1

(8)

IO
2

+

Lb I
Lb

VClamp

As a result, the ratio of ILa and ILb is determined only by
the ratio of Da and Db without depending on the circuit
parameters. Therefore, the inductor current balance can beachieved automatically by satisfying the condition of Da = Db,
where ILa and ILb share half of IO as follows:

I La = I Lb =

QS1a

QP1a

QCt = I La Da TS − I Lb DbTS = 0
I La Db=
I Lb DanS(6)Considering the charge balance at Ct in a steady state, theamount of charge flowing into Ct in state 1 and the amount ofcharge flowing out from Ct in state 3 are the same, so thefollowing equation is obtained.

I La Da = I Lb DbnP

COSince the output current IO of the ACF converter with theproposed 2-phase SC-SR is supplied through La and Lb, thefollowing equation is given.



IO

Cclamp,a+

C. Inductor current sharing
In terms of cooling the inductors, it is important toproperly share the output current between the two inductors.
This paper presents that the proposed 2-phase SC-SR canachieve the automatic inductor current balancing without theneed for control under ideal conditions.

I O = I L = I La + I Lb

+

IL

QS2b

Fig. 7. Active clamp forward converter with 2-parallel conventional
synchronous rectifiers.

current control is necessary to achieve the inductor current
balance. The ACF converter with the 2-parallel conventional
SRs shown in Fig. 7 can reduce the number of circuit elements,
but it cannot achieve the interleaved operation and current
balancing because the inductor current distribution depends
on the circuit parameters. The ACF converter with theproposed 2-phase SC-SR can achieve the interleaved
operation and current balancing by adding only one flying
capacitor to the 2-parallel conventional SRs.

(9)

In practice, there are the dead-time periods in addition to
the main circuit states shown in Figs. 3 and 4, so somecompensation may be required to achieve the perfect current
balance. However, if the current imbalance in the proposed 2phase SC-SR is practically permissible, there is a sufficientpossibility of practical use.

III.

TABLE I summarizes the discussions and shows thecomparison of the circuit configurations. Although the 2parallel ACF converters with the conventional SR shown in
Fig. 6 require many circuit elements, the interleave operation
is applicable. However, due to parameter variations, the

EXPERIMENTAL VERIFICATION

A. Experomental setup and conditions
To demonstrate the feasibility of the proposed 2-phase SCSR, experiments were conducted with the ACF converter
prototype shown in Fig. 8. The primary circuit and transformer

908

TABLE II.

QP1

QP2

Transformer (4:1)

EXPERIMENTAL CONDITIONS AND SELECTED COMPONENTS.

Parameters

Value and Design Selection

Input voltage VIN

140 V

Output voltage VOUT

5V

Switching frequency

200 kHz

Transformer turns ratio nP : nS

4:1
600 V, 29 A, RDS(on),max: 99 mΩ,Power MOSFETs QP1-2(a) Primary circuit and transformer

FMC60N099S2A, Fuji Electric
100 V, 180 A, RDS(on),max: 2.3 mΩ,Power MOSFETs
QS1a, QS2a, QS1b, QS2b

To Lb

STH315N10F7-6, STMicroelectronics
20 μF (10 μF x 12), 50 Vdc, X7T,
GCM31CD71H106KE36, Murata
20 μF (10 μF x 12), 50 Vdc, X7T,
GCM31CD71H106KE36, Murata

Flying capacitor Ct

QS1b

Output capacitor CO

QS2b
Ct

Φ1 Φ2 Φ3 Φ4

QS2a

5 μs

VDS,S1a (50 V/div)nS
VDS,S1a,Φ2-4 = n VClamp + VCt
P

QS1a
To La

(b) Proposed 2-phase SC-SR

La

Lb

2 turns

VDS,S2a (50 V/div)

VDS,S1b (50 V/div)nS
VDS,S2a,Φ1 = n VIN - VCt

VDS,S2b (50 V/div)nS
VDS,S2b,Φ3 = n VClamp
PPP

VDS,S1b,Φ2,4 = VCt

Lb

La

nS
VDS,S1b,Φ1 = n VIN

8 turns(a) VDS,S1a, VDS,S2a, VDS,S1b, and VDS,S2b.
Φ1 Φ2 Φ3 Φ4

VO (2 V/div)

5 μs

VO = 5 V(c) Inductors (2 pairs each of 2 turns and 8 turns)
Fig. 8. Experimental prototype for active clamp forward converterwith the proposed 2-phase SC-SR.

was taken from the DC-DC converter for Toyota Yaris HV,and the proposed 2-phase SC-SR, which is the secondary side
rectifier circuit, was fabricated using the 61.0 mm × 58.4 mm
2-layer PCB with replaceable inductors, which was used in
two pairs each of 2 turns and 8 turns. The pair of 2-turninductors was used for the efficiency and waveform
measurements to clearly observe the change in the output
current ripple and its effect due to the interleaved operation of
the proposed 2-phase SC-SR. On the other hand, the pair of 8turn inductors was used for the current balance measurement
to verify the operation of the proposed 2-phase SC-SR incontinuous current mode.

I La =Db
IO
Da + Db

VCt =Da
V ≈ 16 V
Da + Db IN

VCt = 14 V
IL = ILa + ILb = 40 A

IL (20 A/div)

ΔIL = 6.4 A

ILa (20 A/div)
ILa = ILb = 20 A

ILb (20 A/div)(b) VO, VCt, IL, ILa, and ILb.
Fig. 9. Measured waveforms of the proposed 2-phase SC-SR at IO = 40 A.

VO (2 V/div)

The experimental conditions and selected components arelisted in TABLE II. In order to compare the operating
waveforms and efficiency of the conventional SR andproposed 2-phase SC-SR, the conventional SR was
implemented using QS1a, QS2b, and Lb in Fig. 8 (b), where QS1b
was bypassed using a shunt resistor and La was removed. Then,QS1a was operated synchronously with QP1, and QS2b wasalternately turned on and off with QS1a.
The proposed 2-phase SC-SR was operated as shown in
Fig 4. Then, according to (6) and (8), the distribution of ILa
and ILb can be actively changed using Da and Db as follows:

VCt = 17 V

VCt (5 V/div)

Φ1

Φ2

5 μs

VO = 5 V

VDS,S1 (20 V/div)nS
VDS,S1,Φ2 = n VClamp

VDS,S2 (50 V/div)nS
VDS,S2,Φ1 = n VINPP

IL = 40 A

IL (20 A/div)

ΔIL = 10.8 A

Fig. 10. Measured waveforms of the conventional SR at IO = 40 A.

I Lb =

(10)

909

Da
IO
Da + Db(11)

Therefore, the waveforms and efficiency of the proposed
2-phase SC-SR were measured with the perfect current
balance achieved. Since the step-down ratio M also varies
depending on Da and Db in this experiment, Da and Db weremanually adjusted so that the output voltage VO matched thetarget value, which was set to 5 V.

Efficiency [%]B. Measured waveforms and efficiency
Figs. 9 and 10 show the measured waveforms of the
proposed 2-phase SC-SR and conventional SR, respectively.
Although the voltage waveforms of each switch shown in Fig.
9 (a) contain ringing, the steady waveforms are consistent with
Fig. 4, demonstrating the validity of the circuit analysis in thisstudy. In addition, the waveform of VCt shown in Fig. 9 (b)indicates charging in state 1 and discharging in state 3,
demonstrating the expected circuit operation. Furthermore,
the proposed 2-phase SC-SR achieved the interleaved
operation, which reduced the current ripple ΔIL from 10.8 A
to 6.4 A compared to the conventional SR at IO = 40 A.

+ 4.4 %

88
86
84

85.9 %

82

0

5

Conv.
Prop.

10 15 20 25 30 35 40 45
Output current IO [A]Fig. 11. Measured efficiency comparison between the ACF converters withthe proposed 2-phase SC-SR and conventional SR.

60
50

Current [A]

40
30
20

ILa
ILa
ILb
ILb

10
0
0

20

40
60
80
Output current IO [A]100

Fig. 12. Measured inductor DC currents in the ACF converter with theproposed 2-phase SC-SR.

Current imbalance [%]Figs. 12 and 13 show the measured inductor DC currents
and normalized current difference between the inductors in the
proposed 2-phase SC-SR. As the output current increased, thecurrent imbalance decreased and was below 10% at heavyload. Since the heat generation of the inductors is dominant
under heavy load, the experimental results demonstrate thepracticality of the proposed 2-phase SC-SR. It is expected thatthe current imbalance can be further reduced by proposing acompensation operation that considers the dead time, which isone of the important issues in future work.

90

80

Fig. 11 shows the measured efficiency comparison
between the ACF converters with the proposed 2-phase SCSR and conventional SR. The peak efficiency of the proposed
2-phase SC-SR and conventional SR is 90.3 % and 85.9 % at
IO = 28 A, respectively, resulting in the improvement inefficiency by 4.4 %. In addition, compared with theconventional SR, the proposed 2-phase SC-SR can reduce theefficiency drop under heavy load. These results indicate thatthe proposed SC-SR can reduce the heat generation in the
inductors under heavy load conditions.
C. Measured inductor current difference
In order to demonstrate the practicality of the proposed 2phase SC-SR, the experiment was conducted to show how
much current balance can be achieved without any control orcompensation. In this experiment, both Da and Db were set
constant at 40% and VO was not regulated.

90.3 %

92

15
10

5

ILa
ILa
ILb
ILb

0
-5
-10
-15
0

20

40
60
80
Output current IO [A]100

Fig. 13. Normalized current difference between the inductors in the ACF
converter with the proposed 2-phase SC-SR.

IV. CONCLUSIONS
A 2-phase series capacitor synchronous rectifier (SC-SR)
in active clamp forward (ACF) converters was proposed tosolve the output inductor cooling problems caused by the
recent trend of increasing the output current. This paper
presented that the proposed 2-phase SC-SR achieved theinterleaved operation by adding only one flying capacitor to
the 2-parallel conventional SRs without increasing the numberof the primary circuit elements and transformer. In addition,
the inductor current balancing in the proposed 2-phase SC-SR
was analytically described based on the ideal circuit operation.

proposed 2-phase SC-SR and conventional SR was 90.3 %and 85.9 % at 28 AOUT, resulting in the improvement inefficiency by 4.4 %. The current imbalance between the two
output inductors of the proposed 2-phase SC-SR was less than
10% under heavy load even without any control orcompensation. These results demonstrated the practicabilityof the proposed 2-phase SC-SR in ACF converters.
As future work, a parameter optimization including thedead time and the active clamp capacitance of ACF converter
will be conducted to improve the converter performance. In
addition, a control strategy to achieve the output voltage
regulation and the inductor current balancing at the same time
will be proposed.

In the measurement at 140 V-to-5 V conversion, theinterleaved operation of the proposed 2-phase SC-SR reduced
the output current ripple from 10.8 A to 6.4 A compared to theconventional SR at 40 AOUT. The peak efficiency of the

910

[6]

M. T. Zhang, M. M. Jovanovic, and F. C. Y. Lee, “Analysis andevaluation of interleaving techniques in forward converters,” IEEE
Transactions on Power Electronics, vol. 13, no. 4, pp. 690–698, Jul.
1998.
[7] Y. Lo, T. Kao, and J. Lin, “Analysis and design of an interleaved
active-clamping forward converter,” IEEE Transactions on Industrial
Electronics, vol. 54, no. 4, pp. 2323–2332, Aug. 2007.
[8] T. Jin, K. Zhang, K. Zhang, and K. Smedley, “A new interleaved series
input parallel output (ISIPO) forward converter with inherent
demagnetizing features,” IEEE Transactions on Power Electronics, vol.
23, no. 2, pp. 888–895, Mar. 2008.
[9] K. Nishijima, K. Harada, T. Nakano, T. Nabeshima, and T. Sato,“Analysis of double step-down two-phase buck converter for VRM,”
in Proc. IEEE Telecommunications Energy Conference (INTELEC),
2005, pp. 497–502.
[10] J. Yungtaek, M. M. Jovanovic, and Y. Panov, “Multiphase buckconverters with extended duty cycle,” in Proc. IEEE Applied PowerElectronics Conference and Exposition (APEC), 2006, pp. 38–44.
[11] B. Oraw, and R. Ayyanar, “Small signal modeling and control designfor new extended duty ratio, interleaved multiphase synchronous buckconverter,” in Proc. IEEE Telecommunications Energy Conference(INTELEC), 2006, pp. 1–8.
[12] P. S. Shenoy, M. Amaro, J. Morroni, and D. Freeman, “Comparison of
a buck converter and a series capacitor buck converter for highfrequency, high-conversion-ratio voltage regulators,” IEEE
Transactions on Power Electronics, vol. 31, no. 10, pp. 7006–7015,
Oct. 2016.
[13] P. S. Shenoy, O. Lazaro, M. Amaro, R. Ramani, W. Wiktor, B. Lynch,
and J. Khayat, “Automatic current sharing mechanism in the seriescapacitor buck converter,” in Proc. IEEE Energy Conversion Congress
and Exposition (ECCE), 2015, pp. 2003–2009.

ACKNOWLEDGMENT
This work was partly supported by JSPS KAKENHI Grant
Number 22K14235.
REFERENCES
[1]

[2]

[3]

[4]

[5]

Q. M. Li, and F. C. Lee, “Design consideration of the active-clamp
forward converter with current mode control large-signal transient,”
IEEE Transactions on Power Electronics, vol. 18, no. 4, pp. 958–965,
Jul. 2003.
B.-R. Lin, K. Huang, and D. Wang, “Analysis, design, andimplementation of an active clamp forward converter with synchronousrectifier,” IEEE Transactions on Circuit and Systems I, vol. 53, no. 6,
pp. 1310–1319, Jun. 2006.
P. Rehlaender, T. Grote, F. Schafmeister, and J. Boecker, “Analyticalmodeling and design of an active clamp forward converter applied as asingle-stage on-board DC-DC converter for EVs,” in Proc. PCIM
Europe 2019; International Exhibition and Conference for PowerElectronics, Intelligent Motion, Renewable Energy and Energy
Management, 2019, pp. 1–8.
X. Zhang, B. Nguyen, A. Ferencz, T. Takken, R. Senger, and P. Coteus,“A 12- or 48-V input, 0.9-V output active-clamp forward converter
power block for servers and datacenters,” IEEE Transactions on PowerElectronics, vol. 35, no. 2, pp. 1721–1731, Feb. 2020.
D. Kim, Y. Yamauchi, X. Meng, T. Jia, L. McAuliffe, T. Takken, K.
Tien, S. Tian, Y. Yao, A. Ferencz, M. Seok, and X. Zhang, “Anintegrated programmable gate timing control and gate driver chip for a
48V-to-0.75V active-clamp forward converter power block,” in Proc.
IEEE Energy Conversion Congress and Exposition (ECCE), 2020, pp.
130–134.

911