1. DESIGN AND IMPLEMENTATION OF SOFT
SWITCHED HIGH GAIN CURRENT FED FULL
BRIDGE DC-DC CONVERTER FOR FUEL CELL
APPLICATIONS
Members
D Elangovan
Asst.Prof (Senior)
Siddhartha Nigam
UG Student
Dr.R.Saravanakumar
Professor
Dr.D.P.Kothari
Professor
School of Electrical Engineering , VIT University ,Vellore

2. BACKGROUND TO THE RESEARCH
Recently, green power concept has potentially attracted the attention of researchers,
industries as well as common men.
With the concept of smart grid, smart meters and smart buildings, alternative energy sources
are getting increasingly importance
The alternative energy sources cannot be used as such as they provide unregulated electric
power.
A power electronics interface is required to convert power from alternative energy sources
into usable power for several applications including grid-interface, vehicles, residential or
standalone load applications

3. BACKGROUND TO THE RESEARCH
Among fuel cells, wind & solar power, fuel cells are considered a potential and
capable candidate energy source as they can provide continuous power in all
seasons as long as the continuity of fuel supply is maintained.

Fuel cells are regarded as one option for a more environmentally friendly energy
market in the future.[1]


4. The main issues in power generation using fuel cell:
 High efficiency during load operation
 Large step-up ratio
 Low input ripple current to increase the fuel cell lifetime.
Challenges:
 Design and interfacing an efficient and low cost
power converter.

5. Literature Review

Boost Converter-The boost converter is one of
the most important non isolated converter
A
conventional boost converters are able to
achieve high step-up voltage gain in heavy duty
 Vo
= Vdc / (1-D) where D is the duty ratio = Ton / T

6. Literature Review




With a very high duty ratio, the
output rectifier conducts for only a
very short time during each
switching cycle
Very narrow turnoff pulses
Serious output diode reverse
recovery problem
The switch-off loss due to the
rectifier diode will degrade the
efficiency

7. Literature Review
Topology : Interleaved boost – Non isolated
Ref.no
Journal
Topic
[2]
IEEE Trans.
Power
Electron,
Mar.2008
Voltage multiplier cells
applied to non-isolated
DC–DC converters
[3]
IEEE Trans.
Power
Electron,
Jul.2007
Interleaved
boost
converter for PFC front
end,”
IEEE
Int.
Symp. Power
Electron.
(ISIE), Jun.
2003
An interleaved boost
DC–DC converter with
large conversion ratio
[4]
Strengths
 High
voltage
gain
without high duty ratio
 diode reverse recovery
issues
weaknesses
Requires additional resonant
inductors to cope with the
diode
reverse
recovery
problem

8. Topology : Coupled Inductor
Ref.No
Journal
Topic
Strengths
[5]
IEEE
Trans.
Power
Electron,
Jul.2008
“A family of interleaved
DC–DC
converters
deduced from a basic
cell
with
coupled
inductors,”
[6]
IEEE Vehicle
Power
Propulsion
Conf. (VPPC),
Sep.2007
A novel high efficiency
high power interleaved
coupled-inductor boost
DC–DC converter for
hybrid and fuel cell
electric vehicle
Interleaved converter is an
attractive solution for high
voltage gain applications, but
it is complex and high cost
(two sets of power devices,
magnetic core & control
circuit)
IEEE
Trans.
Ind.
Electron,Feb.
2007
High-efficiency DC–DC
converter
with
high
voltage
gain
and
reduced switch stress,
[7]
diode reverse recovery
affects the overall efficiency
coupled inductor turns ratio
that allows to boost the output
voltage without high duty
ratio
weaknesses
Leakage inductance of the
coupled inductor affects the
efficiency

9. Topology : Coupled Inductor
Ref.No
Journal
Topic
[ 11 ]
IEEE Trans.
Power
Electron,
Jan.2003
“High-efficiency,
high
step-ip
DC–DC
converters,
[10]
IEE
Proc.
Electr. Power
Appl,
Mar. 2004
“Novel
high-efficiency
step-up converter
[9]
IEE
Proc.
Electr. Power
Appl,
Jul. 2005
“High-efficiency DC/DC
converter
with
high
voltage gain,
Strengths
weaknesses
Rectifier diode turnoff
current is limited by leakage
inductance of the coupled
inductor itself.
Additional clamping circuit is
necessary to circulate leakage
energy

10. Topology : Flyback Converter
Ref.no
Journal
Topic
[ 13 ]
IEEE Trans.
Power
Electron,
Nov.2011
High
Step-Up
Ratio
Flyback Converter With
Active Clamp and Voltage
Multiplier
Proc. IEEE
Appl. Power
Electron,
Jul.2006
A low power topology
derived from flyback
with active clamp based
on a very simple
transformer
IEEE Trans.
Power
Electron,
Nov.2005
Analysis, design and
implementation of an
active clamp flyback
converter
[15]
[17]
Strengths
 High
voltage
gain
without high duty ratio
 diode reverse recovery
issues
Combines Isolation with
soft commutation
weaknesses
 Voltage stress across the
rectifier diode
Single winding carries a
current
Operates in discontinuous
mode
High off state voltage
 core utilization

11. Topology : Half bridge DC-DC Converter
Ref.no
Journal
Topic
[ 18 ]
ELSEVIER
Interleaved soft-switched
active-clamped L–L type
current-fed
half-bridge
DC–DC converter for fuel
cell applications
International
Journal of
hydrogen energy
3 4 ( 2 0 0 9)
[19]
[20]
IEEE Trans.
Inds Electron,
Jan 2012
IEEE
Trans
ENERGY
CONVERSION
Jun. 2007
Analysis, Design and
Experimental Results of
Wide Range ZVS ActiveClamped
L-L
Type
Current-Fed
DC/DC
Converter for Fuel Cells to
Utility Interface
Fuel Cell Generation
System With a New Active
Clamping Current-Fed
Half-Bridge Converter
Strengths
weaknesses
 High voltage gain
without high duty ratio
Output diode suffers from
reverse recovery problem.
 Justified Current fed
topology is best for fuel
cell application
The isolation transformer
turns ration is high
High
compared
topologies
efficiency
to
other

12. Filling knowledge gap
Topology : Fullbridge DC-DC Converter
Ref.no
Journal
Topic
Strengths
[ 22 ]
IEEE
2012
Control Design of Currentfed Full-bridge Isolated
Dc/Dc Converter with
Active-clamp
 High Power compared
with half bridge
[23]
[24]
IEEE Trans.
Power Electr,
Jan 2008
Current-fed
Full-bridge
Boost Converter with Zero
Current Switching for High
Voltage Applications
IEEE Trans.
Power Electr,
Mar 2007
Analysis & Implementation
of a High Efficiency,
Interleaved Current-Fed
Full Bridge Converter for
Fuel Cell System
 High efficieny.
weaknesses
Output diode suffers from
reverse recovery problem.
The isolation transformer
turns ration is high

13. Conclusion


High voltage gain possible without high duty ratio
Leakage inductance energy is recycled using Clamping circuits
thereby reducing the switch voltage stress

Compact and Cost-effective power supplies with low losses and high
efficiency are major concern.

Our work focuses on reducing the size of power supplies and
maximizing the power density by introducing new Dc-Dc converter

14. Proposed Converter

15. STEADY STATE ANALYSIS
OF THE PROPOSED
CONVERTER

16. Modes of operation
Mode-1

17. At t=t2, iLk=0 and thus

18. Mode-2

20. Mode-3

21. Mode-4

22. Mode-5

23. Mode-6

24. Equivalent circuits

25. Theoretical Waveforms

26. Half-Wave Cockroft-Walton
Voltage Multiplier
OPTIMAL DESIGN CALCULATIONS
REFERENCE:Ioannis C. Kobougias and Emmanuel C. Tatakis (2010),
“Optimal Design of a Half-Wave Cockcroft–Walton Voltage Multiplier
With Minimum Total Capacitance”.
IEEE Trans. Power Electron., VOL. 25, NO. 9.

27. • The C-W VM circuit topology is an easy and an efficient way
of achieving a high voltage conversion ratio.
• Due to the AC impedance of the capacitors, there is a voltage
drop and a peak to peak ripple when the circuit is fully
loaded.
• Moreover, most of the C-W VM circuits are designed with
equal capacitances.

28. Choice of capacitance
• Thus, an optimized H-W C-W VM circuit design is chosen.
• There are 4 optimal design cases present for the V-M circuit present
Case 1:
C2i = C2i−1 = C (the classical case where all capacitors are equal)
Case 2:
C1=C2 = 2C and C2i = C2i−1 = C for i = 1 (case often found in the bibliography)
Case 3:
C2i = C2i−1 = (n + 1 − i)C
Case 4:
C2i = (n + 1 − i)C and C2i−1 = (n + 1 − i)2C
i : number of every stage
C : capacitance of the last stage, defined as base capacitance.

29. Case 3 can be characterized as the best choice among the four cases for an optimized
design of a H-W C-W VM, because it gives the desired output voltage with a nearly optimum
number of stages, a relatively small voltage ripple and the minimum total capacitance.

30. Simulation of the
Proposed Converter

31. Simulation Parameters
Parameter
Values
Input voltage
30V
Transformer primary turns
25
Transformer secondary turns
25
Output voltage
240V
Switching Frequency
100KhZ

34. Input & Output Voltage

35. Transformer Primary &
Secondary Voltage

36. ZCS

37. HARDWARE IMPLEMENTATION

38. Hardware Model
Voltage
Multiplier
High
Frequency
Transform
er
Source
CSI
Step
Down
Transform
er
Rectifier
with filter
Microcontrolle
r and driver

41. Conclusion
•The size of the transformer gets reduced and the
•Efficiency of the proposed method is more compared to the conventional
method

42. References
[1] Prasanna U R, Member, IEEE, and Akshay K Rathore, Member, IEEE ,” Analysis and Design of ZeroVoltage-Switching Current-Fed Isolated Full-Bridge Dc/Dc Converter” IEEE PEDS 2011, Singapore, 5 - 8
December 2011
Interleaved boost – Non isolated
[2] M. Prudente, L. L. Pfitscher, G. Emmendoerfer, E. F. Romaneli, and R. Gules, “Voltage multiplier cells
applied to non-isolated DC–DC converters,” IEEE Trans. Power Electron., vol. 23, no. 2, pp. 871–887, Mar.2008
[3] Y. Jang and M. M. Jovanovic, “Interleaved boost converter with intrinsic voltage-doubler characteristic for
universal-line PFC front end,” IEEE Trans. Power Electron., vol. 22, no. 4, pp. 1394–1401, Jul.2007.
[4] R. Gules, L. L. Pfitscher, and L. C. Franco, “An interleaved boost DC–DC converter with large conversion
ratio,” in Proc. IEEE Int. Symp. Power Electron. (ISIE), Jun. 2003, vol. 1, pp. 411–416

43. References
- Coupled Inductor
[5] W. Li and X. He, “A family of interleaved DC–DC converters deduced from a basic cell with windingcross-coupled inductors,” IEEE Trans.Power Electron., vol. 23, no. 4, pp. 1791–1801, Jul. 2008.
[6] S.M. Dwari and L. Parsa, “A novel high efficiency high power interleaved coupled-inductor boost
DC–DC converter for hybrid and fuel cell electric vehicle,” in Proc. IEEE Vehicle Power Propulsion
Conf. (VPPC), Sep.2007, pp. 399–404
[7] R. J. Wai, C. Y. Lin, R. Y. Duan, and Y. R. Chang, “High-efficiency DC–DC converter with high
voltage gain and reduced switch stress,” IEEE Trans. Ind. Electron., vol. 54, no. 1, pp. 354–364,
Feb. 2007.
[8] T. J. Liang and K. C. Tseng, “Analysis of integrated boost-flyback step-up converter,” IEE Proc.
Electr. Power Appl., vol. 152, no. 2, pp. 217–225,Mar. 2005.

44. References
[9]
- Coupled Inductor
R. J. Wai and R. Y. Duan, “High-efficiency DC/DC converter with high voltage gain,” IEE Proc.
Electr. Power Appl., vol. 152, no. 4, pp. 793–802, Jul. 2005
[10] T. J. Liang and K. C. Tseng, “Novel high-efficiency step-up converter,”IEE Proc. Electr. Power
Appl., vol. 151, no. 2, pp. 182–190, Mar. 2004.
[11] Q. Zhao and F. C. Lee, “High-efficiency, high step-ip DC–DC converters,”IEEE Trans. Power
Electron., vol. 18, no. 1, pp. 65–73, Jan. 2003.

45. References
- Flyback
[12] A. Bakkali, P. Alou, J. A. Oliver, and J. A. Cobos, “Average modeling and analysis of a flyback with
active clamp topology based on a very simple transformer,” in Proc. IEEE Appl. Power Electron.
Conf. (APEC), 2007,pp. 500–506
[13] Giorgio Spiazzi, , Paolo Mattavelli, and Alessandro Costabeber “High Step-Up Ratio Flyback
Converter With Active Clamp and Voltage Multiplier” IEEE Trans.on power Electronics,VOL. 26,
NO. 11, NOVEMBER 2011

46. References
1. B.R.Lin, K.Huang, and D.Wang, (2005) “Analysis and Implementation of Full
Bridge Converter with Current Doubler Rectifier ”, in IEEE Proceedings Electric
PowerApplications,Vol.152,No.5, pp.1193–1202.
2. Juergen Biela, Member, IEEE, Owe Badstuebner, Student Member, IEEE, and
JohannW. Kolar, Senior Member, IEEE (2009),“Impact of Power Density
Maximization on Efficiency of DC–DC Converter Systems” , IEEE Ttransactions
on Power electronics, Vol. 24, No. 1.
3. Tereň, A., Feňo, I., Špánik, P (2001), “DC/DC Converters with Soft (ZVS)
Switching.” In Conf. Proc. ELEKTRO 2001, section -Electrical Engineering.
Zilina, pp. 82-90,
4. Y. Jiang, Z. Chen, J. Pan, X.I Zhao, and P. Lee (2008) , “A novel phase-shift fullbridge converter with voltage-doubler and decoupling integrated magnetics in

47. References
6. Ioannis C. Kobougias and Emmanuel C. Tatakis (2010), “Optimal Design of a
Half-Wave Cockcroft–Walton Voltage Multiplier With Minimum Total
Capacitance”. IEEE Trans. Power Electron., VOL. 25, NO. 9.
7. M. Prudente, L. L. Pfitscher, G. Emmendoerfer, E. F. Romaneli, and R. Gules
(2008), “Voltage multiplier cells applied to non-isolated DC-DC converters,”
IEEE Trans. Power Electron., vol. 23, no. 2, pp. 871–887.
8. J. M. Kwon and B. H. Kwon (2009), “High step-up active-clamp converter with
input-current doubler and output-voltage doubler for fuel cell power systems,”
IEEE Trans. Power Electron., vol. 24, no. 1, pp. 108–115.
9. Y. Hsieh, T.Hsueh, and H.Yen (2009), “An Interleaved boost converter with
zero-voltage transition, “ IEEE Trans. Power Electron., Vol.24, NO.4, pp.973978.

48. References
- Flyback
[14] P. Alou, O. Garc´ıa, J. A. Cobos, J. Uceda, and M. Rasc´on, “Flyback with active clamp: A suitable
topology for low power and very wide input voltage range applications,” in Proc. IEEE Appl. Power
Electron. Conf. (APEC), 2002, pp. 242–248.
[15] P. Alou, A. Bakkali, I. Barbero, J. A. Cobos, and M. Rascon, “A low power topology derived from
flyback with active clamp based on a very simple transformer,” in Proc. IEEE Appl. Power
Electron. Conf. (APEC), 2006, pp. 627–632.
.
[16] N. P. Papanikolaou and E. C. Tatakis, “Active voltage clamp in flyback converters operating in
CCM mode under wide load variation,” IEEE Trans. Ind. Electron., vol. 51, no. 3, pp. 632–640,
Jun. 2004.
[17] B. R. Lin, H. K. Chiang, K. C. Chen, and D. Wang, “Analysis, design and implementation of an
active clamp flyback converter,” in Proc. IEEE Power Electron. Drive Syst. (PEDS), 2005, pp. 424–
429.

49. References
- Halfbridge
[18] Akshay K. Rathore, Interleaved soft-switched active-clamped L–L type current-fed half-bridge DC–
DC converter for fuel cell applications, International journal of hydrogen energy 3 4 ( 2 0 0 9 )
page no 9 8 0 2 – 9 8 1 5
[19] Akshay K. Rathore, Ashoka K. S. Bhat and Ramesh Oruganti “Analysis, Design and Experimental
Results of Wide Range ZVS Active-Clamped L-L Type Current-Fed DC/DC Converter for Fuel
Cells to Utility Interface “IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 59, NO.
1, JANUARY 2012
.
[20] Su-Jin Jang, Chung-Yuen Won, Byoung-Kuk Lee, “Fuel Cell Generation System With a New
Active Clamping Current-Fed Half-Bridge Converter”, IEEE TRANSACTIONS ON ENERGY
CONVERSION, VOL. 22, NO. 2, JUNE 2007
[21] S.-K. Han, H.-K. Youn, G.-W. Moon, M.-J. Youn, and Y.-H. Kim, “A new active clamping zerovoltage switching PWM current-fed half-bridge converter,” IEEE Trans. Ind. Electron., vol. 20, no.
6, pp. 1271–1279, Nov.2005.

50. References
- Full bridge
[22] Prasanna UR, and Akshay K. Rathore, “Control Design of Current-fed Full-bridge Isolated Dc/Dc
Converter with Active-clamp,” 978-1-4673-0158-9/12/$31.00 ©2012 IEEE
[23] Jiann-Fuh Chen, Ren-Yi Chen, and Tsorng-Juu Liang,” Study and Implementation of a SingleStage Current-Fed Boost PFC Converter With ZCS for High Voltage Applications,” IEEE
TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 1, JANUARY 2008
.
[24] Xin Kong, and Ashwin M. Khambadkone, “Analysis & Implementation of a High Efficiency,
Interleaved Current-Fed Full Bridge Converter for Fuel Cell System”, IEEE TRANSACTIONS ON
POWER ELECTRONICS, VOL. 22, NO. 2, MARCH 2007
[25] G. Moschopoulos and P. Jain, “Single-stage ZVS PWM full-bridge converter,” IEEE Trans. Aerosp.
Electron. Syst., vol. 39, no. 4, pp.1122–1133, Oct. 2003.
Thank you