A Comparison of the Series-Parallel Compensation Type DC-DC Converters
using both a Fuel Cell and a Battery

Koji Orikawa

Jun-ichi ItohStudent Member, IEEE
Nagaoka University of Technology
1603-1 Kamitomioka-machi, Nagaoka-city, Niigata, Japanorikawa@stn.nagaokaut.ac.jp

Member, IEEE
Nagaoka University of Technology
1603-1 Kamitomioka-machi, Nagaoka-city, Niigata, Japan
itoh@vos.nagaokaut.ac.jp

Abstract -- This paper describes the comparison of two
proposed circuits in terms of the efficiency. Series-parallel
compensation type DC-DC converters have been proposed forhybrid power supplies using both fuel cell and battery. The
output voltage is controlled by a series converter that regulates
only the differential voltage between the fuel cell voltage and theoutput voltage. Although the load condition is changed, thevariation of the fuel cell current is suppressed by a battery
through operation of the parallel converter. The experimental
results confirmed that the proposed circuit could achieve
maximum efficiency point of 98.8% and 99.1% in the small
differential voltage region, respectively. In addition, the loss
distribution of the each proposed circuit is clarified by the loss
analysis. As a result, it is confirmed that the optimizing of thereactor is required in order to improve the efficiency of the
proposed circuit.

compensation type DC-DC converters have been proposed
for hybrid power supplies using both fuel cell and battery [9].
The proposed system consists of a series converter and aparallel converter to control the input current and the output
voltage respectively. In the proposed circuit, the series
converter generates a positive and negative voltage toachieve boost and buck operation. On the other hand, theparallel converter with a battery compensates the quick
response according to the load fluctuations. A control
strategy is also proposed to achieve the quick response overthe load and to slow down the power fluctuation of the fuelcell.
This paper discusses about the comparison of two
proposed series-parallel type DC-DC converters in order toclarify the advantages of each converters. Two type of theseries-parallel compensation type converters are proposed
depending on the location of a reactor in the converter. First,
the principle of the proposed DC-DC converter is introduced.
In the proposed converter, the output power is directly
provided by the fuel cell without any switching operation.
Besides, the power rating of the DC-DC converter can be
drastically reduced. As a result, high efficiency is obtained.
Next, the configuration comparison of the proposed circuits
in terms of the efficiency is described. After that, the loss
analysis clarified the loss distribution of the each proposed
circuit. As a result, it is confirmed that the optimizing of thereactor is needed in order to improve the efficiency of the
proposed circuit. In addition, the design of the reactors is
described with considering a suppression method on the
ripple current of the fuel cell where the ripple will influence
the lifetime of the fuel cell. Finally, the experimental results
are presented to demonstrate the advantages of the proposed
converter.

Index Terms—DC-DC power conversion, Fuel cells, Reactors

I.

INTRODUCTION

Recently, fuel cell systems are being developed as a new
power supply for mobile devices because the mobile
electronic devices are developed with increasingly highperformance and functionality, accompanied by larger power
consumption and the demand for longer operation times. A
resonant type converter, which use zero voltage switching or
zero current switching, is one of the most effective circuit
topologies to obtain high efficiency [1-2]. However, theconventional DC-DC converter converts all the power
regardless of the output voltage because the conventional
converter is connected in parallel to a power supply and aload.
Many DC-DC converter circuit topologies for fuel cellapplications have been studied in order to obtain highefficiency [3-5]. However, a fuel cell requires a battery or anelectric double layer capacitor (EDLC) to compensate thedynamic response, because fuel cell cannot respond to aquick load fluctuation. A hybrid power supply using both thefuel cell and battery also requires the following; highefficiency, downsizing, and quick response to load
fluctuations. Nowadays, hybrid power supplies using boththe batteries and fuel cells are being actively studied [6-8].
In order to achieve these requests, series-parallelII.
A.

CONCEPT OF PROPOSED CIRCUIT

Series compensation
Fig. 1(a) presents a block diagram of a conventional buckboost chopper. These converters convert all the input power,
which is not dominated by the relations between the input
and output voltage. For example, in a conventional buck-boost chopper, which consists of a energy storage reactor anda single switching device, when the input voltage Vin isclosed to the output voltage Vout, the duty ratio D of a single
stage buck boost chopper is obtained by (1), using the ontime ton, and off time toff.
D=

t on
Vout
=
= 0.5
t on + t off Vin + Vout(a) Conventional topology.

(1)

In this case, switching devices should be operated
regardless of the relations between the input voltage and theoutput voltage. Besides, the energy for the output should becharge by an intermediate reactor or capacitor. As a result,the efficiency will be decreased.
Fig. 1(b) shows a block diagram of the series
compensation converter, which is connected in series to thepower supply. The series converter outputs only thedifferential voltage between the fuel cell voltage and theoutput voltage. Therefore, when the fuel cell voltage is closed
to the output voltage, the output power is directly provided
by the fuel cell without any switching operation; therefore,high efficiency is obtained by the series compensation circuit,although fluctuation of the output current directly becomes afluctuation of the fuel cell current due to the seriesconnection, which will decrease the lifetime of the fuel cell.
A voltage ripple of the fuel cell occurs due to the internal
impedance in the fuel cell.
Series-parallel compensation
Fig. 1(c) shows a block diagram of the proposed seriesparallel compensation converter. In the proposed circuit, theparallel converter is connected in parallel to the fuel cell.
When the output power is constant, the parallel converter
does not operate, and the series compensation method canobtain high efficiency. The output voltage Vout is obtained by(2), using the series converter output voltage Vconv and thefuel cell voltage Vfc.
Vout = V fc ± Vconv(2)(b) Series compensation topology.

(c) Concept of proposed converter.
Fig. 1. Block diagrams of proposed converter in comparison with aconventional circuit.

B.

(a) Proposed circuit 1.

When the load condition has changed, the parallel
converter will compensate the quick variation of the fuel cell
current. The fluctuation of the output power is compensatedby the battery through the operation of that parallel converter.
In addition, when the battery voltage is decreased or
overcharged, either the battery will be charged from the fuelcell or the battery supplies the power to the load through theoperation of that parallel converter.
III. PROPOSED CIRCUIT
Fig. 2(a) shows the proposed circuit that a reactor Lfc isconnected in series to the fuel cell in order to suppress the
ripple current of the fuel cell. Further, the reactor is also used
as a boost reactor when the boost mode is selected. In Fig.
2(a), the series converter is operated as a boost converter anda step-down converter. The output of the parallel converter isconnected to the negative terminal of the fuel cell. The
proposed circuit requires only two reactors, where the(b) Proposed circuit 2.
Fig. 2. Proposed circuit.

conventional circuit needs to use three reactors.
Fig. 2(b) shows another type of the proposed circuit that areactor Lcomp is connected to the parallel converter, in order toreduce the conduction loss of the reactor in comparison to
Fig. 2(a). In Fig. 2(a), reactor current Ifc of Lfc is the sum of

the output current ILout and compensation current Icomp.
Therefore, the conduction loss of the reactor will be
increased. On the other hand, in Fig. 2(b), the reactor currentof Lcomp is lower than the output current due to only
fluctuation components of the output power. Therefore, theconduction loss of the reactor Lcomp can be reduced. It isnoted that, the battery voltage must be higher than the fuelcell voltage to prevent a rush current from the fuel cell to thebattery in the proposed circuit 1 and 2.

Vout

(4)

*

I comp =sT*
I Lout1 + sT

-

ACR

+
-

S1
S2

Carrier
Vfc

Icomp*+

Ifc
ILout

+
ACR

Icomp -

-

+
-

+

S3
S4

Timer
Window cmp.

The fuel cell current command Ifc* and the parallel
converter current command Icomp* are obtained by (4) and (5)1*
I Lout1 + sT

Ifc*+

Icomp_refFig. 3 shows the control diagrams of the proposed circuit.
The proposed control method has two loops; the inner loop isfor controlling the fuel cell current and the parallel converter
current. As for the outer loop, it is for the output voltage
control. The same control strategy can be applied to the
proposed circuit 1 and 2 because the fundamental operation is
the same.
Operation between the series and parallel converter isconstrained by the load condition in order to reduce theconverter loss. In boost mode, the series converter works as aboost converter. In this case, the battery supplies the power tothe load, because the differential voltage is positive. In buckmode, the series converter operates as a buck converter. In
this case, the battery is charged from the fuel cell, since thedifferential voltage is negative. The switches S3 and S4 arefor the parallel converter. The parallel converter works only
when the load is fluctuating. The parallel converter will bestarted when the load fluctuation is detected by the window
comparator and is stopped after the time runs longer than thetime constant of the LPF and HPF.
The current command is divided into the fuel cell current
command and the compensation current command. Low passfilters (LPF) and high pass filters (HPF) are used to divide
the current command. The LPF is used to separate thefundamental current fluctuation, for the slow response of thefuel cell. The HPF is used to separate the transient current
fluctuation for the fast response of the battery. The HPF
functions simultaneously with the LPF filter, as shown in Fig.
3. The time constants of the LPF and HPF are set to the samevalue.
The frequency responses of the LPF and HPF do not
influence the output current response, as explained by thefollowing. The relations between each current can be
expressed by (3), using the fuel cell current Ifc and theparallel converter current Icomp.
(3)
I Lout = I fc + I comp*-LPF and HPF
ILout* + AVR
1/sT

Vout

IV. CONTROL STRATEGY

I fc =* +(5)

where T is the time constant of the filter and ILout* is theoutput current command. Therefore, the output current isobtained by (6).

Fig. 3. Control diagrams for the proposed circuit.

I Lout = G1 (s )I fc + G2 (s )I comp
*

*

(6)

where G1(s) and G2(s) are the transfer functions of the fuelcell current control and the parallel converter current control,
respectively.
In addition, the output current is expressed by (7) whenboth the design values of the current regulator for the fuelcell and parallel converter are the same.
*(7)
I Lout = G (s )I Lout
where G(s) is the transfer function of the output current
control. That is, the time constant of the LPF or HPF does notappear in the transfer function of the output current control.
In addition, the operation of the parallel converter is started
by variation of the parallel converter current command Icomp*.
Then, operation of the parallel converter is stopped by a timer
which is used to prevent a decrement of efficiency in the
proposed circuit.
V.

DESIGN OF REACTORSA.

Design of reactors
In the proposed circuit, the ripple current of the reactors
becomes a maximum value when the differential voltage
between the fuel cell voltage and the output voltage are
maximum. The value of the ripple current of the reactor do
influence on the lifetime of the fuel cell.
Fig. 4 shows operation modes of the proposed circuit 1
and 2 in boost mode, respectively. In boost mode, the switch
S2 maintains at on state. The difference voltage is thencontrolled by PWM modulation of S1. The fuel cell current issum of the current of the output reactor and the parallel
converter current. The ripple current of the fuel cell ∆ifc1 and∆ifc2 is obtained by (8) and (9), using the peak value of theparallel converter current ∆icomp1 and ∆icomp2 which are thediscontinuous triangle waveform, and the ripple current of
the output reactor are ∆iLout1 and ∆iLout2 while S1 is on.
∆i fc1 = ∆icomp1 + ∆iLout1 =V fc 1 V fc − Vout
L fc f sw
Vsb(8)

∆i fc 2 = ∆i comp 2 + ∆i Lout 2⎧⎪ V fc⎫⎪ 1 V fc − Vout
1=⎨+
V fc + V sb − Vout ⎬V sb⎪⎩ Lcomp Lout 2⎪⎭ f sw()(9)

From (8), the ripple current of the fuel cell in the proposed
circuit 1 is inversely proportional to Lfc. From (9), the ripple
current of the fuel cell in the proposed circuit 2 is inversely
proportional to Lcomp and Lout2. When both the ripple currentof the fuel cell in the proposed circuit 1 and proposed circuit
2 are the same, Lcomp which has same ripple current of thefuel cell in the proposed circuit 1 is obtained by (10).
Lcomp =

V fc
L fc

−

V fc
V fc + Vsb − Vout

(10)(a) Proposed circuit 1.

Lout 2

However, the denominator of (10) should be more thanzero. Therefore, Lout2 is obtained by (11).
Lout 2 >V fc + Vsb − Vout
V fc

L fc

(11)

Fig. 5 shows calculation results of the inductance valuesof Lcomp and Lout2 in the proposed circuit 2. Table I shows
design specifications for the reactors. The calculation results
confirmed that Lcomp and Lout2 should be more than 30µH,
58.5µH while Lfc and Lout1 is 30µH, respectively. Note thatthe inductances of the reactors in the proposed circuit 2 areconstrained by (10), (11). Therefore, the inductances of thereactors in the proposed circuit 2 are larger than the ones in
the proposed circuit 1. Because Lcomp contribute tosuppression of the ripple current of the fuel cell only while S1
is on. As a result, Lout2 which always contribute in the
suppression of the ripple current of the fuel cell should belarger. However, the current of Lcomp does not include thedirect current component. Therefore, the core which has alower saturation magnetic flux density than the Lout2 can beselected for use in Lcomp. Therefore, in the proposed circuit 2,
the inductance of Lout2 should be smaller and the inductanceof Lcomp should be larger. However, the ripple current of Lout2
increases if Lout2 is small. As a result, the increasing of thecopper loss which is caused by ripple component will beconsidered. However, major copper loss which is caused by
the direct current component is reduced in Table I condition.
B.

Maximum of the magnetic flux density of the core
In case of Lfc, the magnetic flux density of Lfc is obtainedby (12).
∆B fc =

1
VLfc dt
N1S1 ∫(12)

where N1 is the number of wiring turns of Lfc, S1 is the crosssection area of a core of Lfc and VLfc is the reactor voltage. In
addition, the reactor voltage is the square waveform in the
proposed circuit. Therefore, (12) is also expressed by (13).
∆B fc =

VLfc t on
N1 S1

(13)

where ton is switch on time of S1. ton is obtained from (14).

(b) Proposed circuit 2.
Fig. 4. Operation mode (Boost operation, S1 is on).
TABLE ISPECIFICATIONS FOR DESIGN OF REACTORS
4 to 10 (V)Fuel cell voltage Vfc
Output power Pout
9.3 (W)
Output voltage Vout
7.2 (V)
Battery voltage Vsb
11 (V)
Switching frequency fsw
100 (kHz)
30% of output current (A)Ripple current of the reactor ∆ifc

100
0.3

80
Lcomp

60

Icomp
0.2

40
ILout220

0.1

Lfc, Lout1 (Proposed circuit 1)

0
100 150 200 250 300 350 400 450 500
Lout1, Lout2 [ H]
Fig. 5. Relation of inductances of the reactors and ripple current (Vfc=4V).
0

ton =

0

50

1 V fc − Vout
f sw
Vsb

(14)

On the other hand, the direct current component of themagnetic flux density BDC_fc is proportional to reactor current.
Therefore, it is obtained by (15) using (13).

BDC _ fc =∆B fc
∆i fc1

2

(15)

I out

B peak _ fc = BDC +

∆B fc
2

=

∆B fc
∆i fc

I out +∆B fc
2

Cross-section area ratio

where Iout is the output current which is the average current of
the Lout1. Although the average current of Lfc is actuallydifferent from Iout, there is not much difference between the
average current of Lfc and the output current Iout. Therefore,
the maximum of the magnetic flux density Bpeak_fc isexpressed by (16) using (13), (15).
VLfc t on ⎛ I out
1⎞
⎜
=
+ ⎟
⎜
N1S1 ⎝ ∆i fc1 2 ⎟⎠(16)
In case of Lcomp, the maximum flux density of Lcomp isdominated by the peak of current of Lcomp because it is a
discontinuous triangle waveform. Therefore, the maximum
magnetic flux density Bpeak_comp is expressed by (17).
B peak _ comp =VLcomp t on
N 2 S2(17)

where N2 is the number of wiring turns of Lcomp, S2 is the
cross-section area of a core of Lcomp and VLcomp is the reactor
voltage. In addition, VLfc and VLcomp are the same when onresistance of the switch and forward voltage drop of the freewheeling diode (FWD) are considered to be negligible.
C.

Comparison of cross-section area
Consideration on the theoretical volume of the reactors is
conducted in this paper too. The reactor volume is depended
on several factors which are the maximum magnetic flux
density Bpeak_fc, Bpeak_comp, the cross-section area of the core S1,S2 and the number of the wiring turns N1, N2, respectively. In
order to compare the theoretical volume of the reactors
between the proposed circuit 1 and 2, the cross-section areaof the core is calculated in this section. For example, whenboth the maximum magnetic flux density Bpeal_fc and Bpeak_comp
are the same, relations between the cross-section area of thecore S1 and S2 is expressed by (18).
S2
1
=
S1
⎛
N 2 ⎜ I out
1⎞+ ⎟⎜N1 ⎝ ∆i fc1 2 ⎟⎠(18)

In addition, S1 is 24mm2, N1 is 13 turns.
Fig. 6 shows the calculation result of the cross-section
area of the core. The calculation result confirmed that thecross-section of area of the core S2 can be smaller than thecore S1 if the number of the wiring turns N2 is larger thanabout a quarter of the number in the wiring turns N1.
VI. EXPERIMENTAL RESULTS
A.

Series-parallel compensation operation
The proposed circuit was tested under the experimental
conditions as shown in Table I. The response of the current
regulator was designed as much higher than that of the LPF.
It should be noted that the time constant was set to a shorter

S1: 24 (mm2)N1: 13 (turn)
Area 1: S2 > S1

S2/S1 1
Area 2: S2 < S1

0

1

2
3
Turn ratio N2/N1

4

Fig. 6. Cross-section area of the core.

time in this experimental condition in order to confirm theeffectiveness of the parallel converter. In order to reduce anegative influence on the lifetime of the fuel cell, the time
constant should be set to a few seconds.
Fig. 7 shows waveforms of the fuel cell current and theoutput voltage with the parallel compensation when the loadcondition is changed in the proposed circuit 1. Fig. 4
confirmed that the variation of the fuel cell current issuppressed by the parallel compensation. The output voltage
is kept constant by the PI regulator. The output voltage drops
within 7% is known. It should be noted that the output
voltage waveform has no low frequency component and thefluctuation is in a steady state load.
B.

Efficiency of the proposed circuit
Fig. 8 shows the efficiency of the proposed circuits toconfirm the effectiveness of the series compensation underthe experimental conditions as shown in Table I. The
experimental results confirmed that the proposed circuits
could achieve 98.8% and 99.1% at the maximum efficiency
point in the small differential voltage region, respectively. In
the buck mode, the efficiency of the proposed circuit 2 ishigher than that of the proposed circuit 1. In contrast, theefficiency of the proposed circuit 2 is lower than that of the
proposed circuit 1 when the fuel cell voltage is in boost mode.
Fig. 9 shows equivalent circuits of the proposed circuit 1
and 2 in buck mode, respectively. In the proposed circuit 1,
the current flows through the parallel converter. That is, thecurrent flows through FWD of switch S4. On the other hand,the current does not flow through the FWD of S4 in the
proposed circuit 2. This reason is because the battery voltage
is higher than the fuel cell voltage. As a result, FWD of S4 in
the proposed circuit 2 will not be an on state. Therefore,
FWD loss in the parallel converter is not occurring. In
addition, the loss of the reactor Lcomp is not occurring either
because the current does not flow through the parallel
converter. As a result, the sums of the reactor loss in the
proposed circuit 2 are reduced. Therefore, the efficiency ofEfficiency [%]TABLE II
EXPERIMENTAL CONDITIONS
4 to 10 (V)Fuel cell voltage Vfc
Output voltage Vout
7.2 (V)
Battery voltage Vsb
11 (V)
Switching frequency fsw
100 (kHz)
Input reactor Lfc
30 (µH)
Parallel converter reactor Lcomp
30 (µH)
Output reactor Lout1, Lout2
30 (µH)
Output capacitor Cout
800 (µF)
AVR response
0.1 (kHz)ACR response
1 (kHz)
LPF time constant
2.2 (ms)
Load change
2 to 20 (W)Fig. 8. Efficiency of the proposed circuit.

Lfc Vsb

Lout1
FWD of S4

Vfc

Vout
Icomp1(a) Proposed circuit 1.

(a) Series compensation only (proposed circuit 1).
(b) Proposed circuit 2.
Fig. 9. Equivalent circuit of the proposed circuit in buck mode.

circuit 1 in the buck mode.
C.

(b) Series-parallel compensation (proposed circuit 1).

Output voltage Vout

4 [ms/div]

Fuel cell voltage Vfc

0(Vout, Vfc)
0(Ifc)

Vout ,Vfc:
2.0 [V/div]
Fuel cell current Ifc

Ifc ,Icomp:
2.0 [A/div]0(Icomp)
Parallel converter output current Icomp(c) Series-parallel compensation (proposed circuit 2)
Fig. 7. Voltage waveforms and current waveforms for increasing output
power.

the proposed circuit 2 is higher than that of the proposed

Loss analysis
In order to evaluate the power loss of the proposed circuit,the loss measurement and analysis for each part was
implemented under the experimental conditions as shown in
Table I. Fig. 10 shows the result of the loss analysis. The
features of the proposed circuits are the copper loss and theiron loss of the reactors could achieve minimum loss in thesmall differential voltage region (Vfc=7.3V), the proposed
circuit is able to obtain high efficiency. From the loss
analysis, the efficiency of the proposed circuit 2 is higher
than the proposed circuit 1 in buck mode, because the loss of
the reactor has been decreased. On the other hand, in boost
mode, although the copper loss of the reactor is decreased in
the proposed circuit 2, the efficiency of the proposed circuit 2
is lower than the proposed circuit 1. The reason for low
efficiency in the proposed circuit 2 when the fuel cell voltage
is 4V in the boost mode is that the power loss is increased
because of the increasing of iron loss in the reactor. In
conclusion, the proposed circuit 1 is superior for the boost
mode. Then the input voltage has a longer operation time oflower voltage to the output voltage. On the opposite, thecircuit 2 is suitable for the buck mode.

Ripple current of the fuel cellFig. 11 shows the waveforms of the fuel cell current in the
proposed circuit 1 and 2, respectively. The experimental
results confirmed that the fuel cell current contains a ripple
with 100 kHz switching frequency.
Fig. 12 shows the experimental results of the ripple fuelcell current of the proposed circuit 1 and the proposed circuit
2, respectively. The experimental results confirmed that thedesigned reactor could suppress the ripple current of the fuelcell within the set value. Furthermore, the theoretical value
agrees with the experimental results.
CONCLUSION

A series-parallel compensation type DC-DC converter has
proposed to achieve high efficiency, downsizing and longer
lifetime in an application of a fuel cell-battery hybrid system.
When the output power is almost constant, the series
converter provides only the differential voltage between thefuel cell voltage and the output voltage, while the parallel
converter suppresses the variation of the fuel cell current.
The experimental results confirmed that the proposed
circuit could achieve a maximum efficiency of 98.8% and99.1% in the small differential voltage region. In addition,from the loss analysis, it is confirmed that the optimizing of
the reactor is needed in order to improve the efficiency of the
proposed circuit. The proposed circuit 2 is superior in term ofefficiency for the buck operation mode and direct operation
mode. In addition, the design of the reactors is discussed andthe suppression of the ripple in the fuel cell current has been
confirmed with the theoretical calculation and experimental
results.
REFERENCES
[1]
[2]
[3]
[4]

[5]
[6]
[7]

[8]

Fig. 10. Loss analysis of the experimental result.

Yilei Gu, Zhengyu Lu, and Zhaoming Qian, “Three Level LLC Series
Resonant DC/DC Converter,” Proc. of IEEE-APEC04, pp. 1647- 1652
Eui-Sung Kim, Dong-Yun Lee, and Dong-Seok Hyun, “A Novel Partial
Series Resonant DC/DC Converter with Zero-Voltage/Zero-Current
Switching,” Proc. of IEEE-APEC00, pp. 93- 98
Jiann-Fuh Chen, Wei-Shih Liu, Ray-Lee Lin, Tsorng-Juu Liang, andChing-Hsiung Liu, “High-Efficiency Cascode Forward Converter of
Low Power PEMFC System,” Proc. of IEEE-IPEMC06
Changrong Liu, Amy Johnson, and Jih-Sheng Lai, “A Novel ThreePhase High-Power Soft-Switched DC/DC Converter for Low-Voltage
Fuel Cell Applications,” IEEE Trans. Industry Applications, pp. 16911697, 2005
Xin Kong, Ashwin M. Khambadkone, “Analysis and Implementation ofa High Efficiency, Interleaved Current-Fed Full Bridge Converter for
Fuel Cell System,” IEEE Trans. Power Electronics, pp. 543- 550, 2007
H. Tao, A. Kotsopoulos, J. L, Duarte, and M. A. Hendrix, “A SoftSwitched Three Port Bidirectional Converter for Fuel Cell andSupercapacitor Applications,” Proc. of IEEE-PESC05, pp. 2487- 2493
Naehyuck Chang, “Fuel Cell and Battery Hybrid System for Portable
Electronics Applications,” 10th Annual International Conference
SMALL FUEL CELLS 2008 – Portable & Micro Fuel Cells forCommercial & Military Applications, 2008
Zhenhua Jiang, Lijun Gao, and Roger A. Dougal, “Flexible
Multiobjective Control of Power Converter in Active Hybrid Fuel
Cell/Battery Power Sources, ” Proc. of IEEE-PESC04, pp. 3804- 3811

(a) Proposed circuit 1.
(b) Proposed circuit 2.
Fig. 11. Current waveforms of the fuel cell (Vfc=4V).

500
Ripple current of the fuel cell ifc1
[mA]

VII.

Power loss [W]D.

Lfc, Lout1:30 H
Pout:9.3W
fsw:100kHz

400
300
200
100
0

Theoretical result
Experimental result
4567Fuel cell voltage Vfc [V](a) Proposed circuit 1.

500
Lcomp:60 H
Lout2:120 H
Pout:9.3W
fsw:100kHz

400
300
200
100
0

Theoretical result
Experimental result
4567Fuel cell voltage Vfc [V](a) Proposed circuit 2.
Fig. 12. Comparison of the ripple current of the fuel cell.

[9]Koji Orikawa, Jun-ichi Itoh, “High efficiency DC-DC converter using aseries-parallel compensation method for a fuel cell,” The 13th
European Conference on Power Electronics and Applications, pp. 1- 9