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Design and Control of a Multiple Input DC/DC Converter for

Battery/Ultra-capacitor Based Electric Vehicle Power System

Zhihao Li, Omer Onar, and Alireza Khaligh

Energy Harvesting and Renewable Energies Laboratory (EHREL)

Electrical and Computer Engineering Department, Illinois Institute of Technology, 3301 S. Dearborn St.

Chicago, IL 60616; Tel: (312) 567-3444

Email: [email protected]; URL: www.ece.iit.edu/~khaligh

Erik Schaltz

Department of Energy Technology, Aalborg University, Aalborg, Denmark

E-mail: [email protected]

Abstract- Battery/Ultra-capacitor based

electrical vehicles (EV) combine two energy

sources with different voltage levels andcurrent characteristics. This paper focuses

on design and control of a multiple input

DC/DC converter, to regulate output voltage

from different inputs. The proposed

multi-input converter is capable of

bi-directional operation and is responsible for

power diversification and optimization. A

fixed switching frequency strategy is

considered to control its operating modes. A

portion of New York City Cycle that includes

these operation modes is used to perform the

analyses.

I.INTRODUCTION

Concept of electrical vehicles (EV) is a

philosophy that integrates vehicular engineering

and electrical engineering. Energy sources of EV

should satisfy the demands of high energy

density, fast charging and discharging

capabilities, long cycle life, low cost, and low

maintenance [1].

Rechargeable chemical batteries are the

most traditional energy sources for EVs. System

integration and optimization are prime factors to

achieve good performance and affordable cost.

In order to design an EV having comparable

performance with conventional vehicles usinginternal combustion engine (ICE),

battery/ultra-capacitor based power distribution

system is introduced to EV. Proposed

battery/ultra-capacitor system, which is capable

of meeting the demands that vehicle may

encounter under any condition. Battery bank is

capable of supplying the main power to drive the

electric machine; however it is not able to supply

large bursts of power in short durations. For this

reason, the use of ultra-capacitor can be

considered to relieve battery pack from peak

power transfer stress, due to capacitors higher

specific power and cycling efficiency [2].

By combining battery bank and capacitor

tank, it is possible to use a smaller battery with

less peak-output power capability. Therefore, the

cost would decrease significantly and the

efficiency of the energy sources would increase

[3]. Generally, a compact, lightweight, efficientpower system is desired for electrical vehicles

[4]. Fig. 1 shows the configuration of an

electrical vehicle with battery bank and

ultra-capacitor tank as its energy sources,

utilized using a multiple input DC/DC converter.

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Fig. 1. Battery/Ultra-capacitor based EV.

II.CIRCUIT TOPOLOGY AND ANALYSIS

In this paper, a four quadrant multi-input power

electronic converter (MIPEC) is investigated.

The converter is shown in Fig. 2. It is seen that

battery and ultra-capacitor are respectively

connected as inputs to a common inductor

through bi-directional switches. These switches

can be realized by two parallel IGBTs or other

similar devices [5]-[7]. Due to different

conduction cases of diodes and switches, the

converter can be operated in buck, boost and

buck-boost modes for both positive and negative

input powers..

Fig. 2. Multi-Input power electronic converter.

If the inductor current is continuous, it means at

least one switch or one diode is turned on all the

time. Diode is on only if all of switches are

turned off. If more than one switch is turned on

at the same time, the inductor voltage equals to

the highest voltage of the inputs [8]-[12]. In this

research, in order to simplify the operation, we

have following constraints:

UCBattO VVV >>

Inductor current iLis continuousMode A: In this mode, both of the two input

sources deliver power to the output. Because the

voltage level of battery is always higher than

that of the ultra-capacitor, S2Ais turned on all the

time in this mode. The inductor current is

controlled by the switch Q2 and the distribution

of power from the battery and the ultra-capacitor

is controlled by S1A. When the switch Q2 is not

conducting, the diode D3 is turned on. The

multi-input converter is working to boost the

inputs voltage levels, the circuit can be therefore

simplified to the diagram in Fig. 3.

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Fig. 3. Multi-input converter in boost mode.

Let us define VBatt=V1, VUC=V2, CBatt=C1,

CUC=C2, and the equivalent resistance of load

can be defined asRo. In steady-state, the average

inductor voltage is zero. It is assumed that each

switch is operated at the same frequency of 1/Ts

and the leading edge of each signal coincides. In

this mode, there are three intervals based on the

switching frequency and duty rations of the input

switches.

- During the interval of DS1ATs, Q2 is turned on,

and both S1Aand S2Aare conducting, because V1

is higher than V2, so V1is applied to the inductor

for energy storing.

- During the (DQ2-DS1A)Ts interval, when S1A is

turned off, only V2 is effective as the terminal

voltage for inductor, so the ultra-capacitor

supplies energy to the inductor.

- For the (1-DQ2)Ts interval, when Q2 is off, D3

will be turned on to deliver energy to the load.

Since the S2Ais turned on all the time, after Q2is

off, V2 is connected to the load through D3 to

supply the rest of demanded energy. After

state-space averaging, and using state equations

the relationship between inductor current and

duty cycle of switch Q2can be obtained as

2

2

2

2

2 )1(

)1(

)(

)(

QOOO

LOQOOOO

Q

L

DRLssCLR

IRDVsCRV

sD

sI

++

++

= (1)

Mode B: in this regenerative braking mode, the

power is delivered from output to both inputs V1

and V2. The converter works as a buck converter

in this mode. Since the input V2is lower than V1,

the switch S1Bis always turned on. The inductor

current is controlled by switching Q3 and the

distribution of power between V1 and V2 is

controlled by S2B.D2will not be conducting until

Q3is turned off. The two inputs are modeled by

two resistive loads respectively. The circuit can

be reduced as shown in Fig 4.

Fig. 4. Multi-input converter in buck mode.

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In buck mode, ultra-capacitor will get charged

first when both S1B and S2B are conducting.

Therefore, S1Bis turned on all the time. The state

equations can be obtained according to

conducting cases of switches and diodes as

follows:

- In the interval of DS2BTs, Q3 is conducting and

the switch S2B is turned on, the regenerative

power from the load flows into the

ultra-capacitor to and ultra-capacitor is charged.

- During the interval of (DQ3-DS2B)Ts, power

from the load will charge the battery bank

through S1B, after S2B is turned off. In this way,

the power distribution between battery and

capacitor ban be controlled and power

management is provided.

- In the interval of (1-DQ3)Ts, when Q3 is turned

off, D2 is turned on. Since S1B is always

conducting in buck mode, the rest of the energy

stored in the inductor is used to charge the

battery continuously.

By state-space averaging, the state equations can

be obtained and get the relationship between the

inductor current and the duty cycle of switch Q3

as follows:

2

22

2

21

2

21

2

2221

2

2211

3

2121

2211

2

2121

3 )1()))1((()(

)1)((

)(

)(

BSBSBSBS

o

Q

L

DRDsRDCDCRRLsCRCRLsCCRLR

sCRCRsCCRRV

sD

sI

++++++

+++

= ; (2)

III.RESULTS AND ANALYSES

The simulation is based on the New York City

Drive Cycle (NYCC) load profile and lasts for

about 30 seconds. Actually, the whole time

period of NYCC load profile is 600 seconds,

however for the simulation a potion of this drive

cycle is used to perform all modes of operation

instead of using the whole period. In the selected

time period, both accelerating and decelerating

operations are included in order to present the

bi-directional power flow.

The waveform of load current is shown in Fig. 5.

The load current is in accordance to the power

requirement of the drive train. From Fig. 5, it is

seen that the load current starts at t=152, then it

has both increasing and decreasing variationsduring the selected time portion. At about t=166,

the load current becomes negative, which

represents the regenerative braking period. In

this period, energy flows from the load to the

input sources yielding charging of battery and

ultra-capacitor.

Fig. 5. Load current.

Fig. 6 and Fig. 7 show the current waveforms of

battery and ultra-capacitor. Comparing Fig. 6

and Fig. 7, it is shown that the battery current

waveform is much smoother than that of the

ultra-capacitor current. The battery supplies the

main power to the load and there are no

significant oscillations in the battery current

waveform. For the battery, it is not desired to

have large magnitude of oscillations since fast

charging and discharging will reduce the lifetime

of battery. However, the ultra-capacitor has

better and faster cycling characteristics. From

Fig. 7, it is obvious to find that ultra-capacitor is

always handling the fast change of energy

variations. Both battery and ultra-capacitor

enable to follow the power variation of the load

very well, which ensures the ideal performanceof the vehicle during driving conditions.

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1 5 5 1 6 0 1 6 5 1 7 0 1 7 5 1 8 0

- 5

0

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

T i m e [ s ]

B

a

t

t

e

r

y

C

u

r

r

e

n

t

[

A

]

Fig. 6. Battery current.

1 5 5 1 6 0 1 6 5 1 7 0 1 7 5 1 8 0

- 4 0

- 2 0

0

2 0

4 0

6 0

8 0

T i m e [ s ]

Fig. 7. Ultra-capacitor current.

Fig. 8. Bus voltage.

The bus voltage shown in Fig. 8 is almost

constant at 250V with some insignificant

variations around the nominal operation voltage.

Fig. 9. State of charge of battery

Fig. 10. State of charge of UC.

Fig. 9 and Fig. 10 show the state of charge of

battery and ultra-capacitor. The values of state of

charge will not fall too low so as to keep the

input sources have enough energy to supply the

load. In Fig. 10, it is shown that the state ofcharge decreases when the UC current is positive;

and the state of charge increases when the UC

current is negative. The charging and

discharging characteristics of the sources can be

learned from the figures of state of charge.

IV.CONCLUSION

This study presents a battery/ultra-capacitor

based multiple-input buck-boost converter

utilized in a small electric vehicle. The two input

sources are share one common inductor. The

battery bank is designed to supply average

demand power of the vehicle, on the other hand,

ultra-capacitor bank supplies or recaptures the

large bursts of power with high C-rates. In this

topology, only one input inductor is required,

which significantly reduce the cost and size of

the whole system. Input sources are effectively

controlled to deliver desired power levels to the

load fast and accurate enough. Regenerative

energy can be efficiently recaptured by battery

and ultra-capacitor during braking periods. The

proposed topology is able to be extended to

applications using other multi-source

applications.

REFERENCES

[1] C. C. Chan and K. T. Chau, Modern electric

vehicle technology, Oxford University PressInc., New York, 2001

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[2] A. Emadi, M. Ehsani, and J.M. Miller,

Vehiclular Electric Power Systems: Land, Sea,

Air, and Space Vehicles. New York: Marcel

Dekker, 2003.

[3] C. C. Chan, The state of the art of electric

and hybrid vehicles, Proc. IEEE, vol.90,

pp.247-275, Feb.2002.

[4] A. Di Napoli, F. Crescimbini, L. Solero, F.

Caricchi, and F. Giulii Capponi, Multiple-Input

DC-DC Power Converter for Power-Flow

Management in Hybrid Vehicles, Proc. IEEE,

0-7803-7420-7/02/, pp.1578-1585, 2002

[5] B. G. Dobbs and P. L. Chapman, A

Multiple-Input DC-DC Converter Topology,

IEEE. Power Elelctronics Letters, vol, March

2003, pp.6-9

[6] H.-J. Chiu, H.-M. Huang, L.-W. Lin, M.-H.

Tseng, A Multiple-Input DC/DC Converter for

Renewable Energy Systems, 0-7803-9484-4,

IEEE, pp.1304-1308, 2005.

[7] Y. M. Chen, Y. C. Liu, and F. Y. Wu,

Multi-Input DC/DC Converter with

Ripple-Free Input Currents, IEEE PESC, vol, 2,

June 2002, pp.796-802

[8] A. D. Napoli, F. Crescimbini, F. Giulii

Cappponi, and L. Solero, Control Strategy for

Multiple Input DC-DC Power Converters

Devoted to Hybrid Vehicle Propulsion Systems,

IEEE, vol, 2005, pp.1036-1041

[9] F. Caricchi, F. Crescimbini, A. Di Napoli, O.

Honorati and E. Santini, Testing of A New

DC-DC Converter Topology For Integrated

Wind-Photovoltaic Generating Systems, The

European Power Electronics Association, vol,

1993, pp. 83-88

[10] H. Matsuo, K. Kobayashi, Y. Sekine, M.

Asano, and L. Wenzhong, Novel Solar Cell

Power Supply System Using the Multiple-Input

DC-DC Converter, IEEE, vol, 1998,

pp.797-802

[11] B. Ozpineci, L. M. Tolbert, and Z. Du,

Multiple Input Converters for Fuel Cells,

IEEE, vol, 2004, pp.791-797

[12] M. Marchesoni, C. Vacca, New DC-DC

Converter for Energy Storage System Interfacing

in Fuel Cell Hybrid Electric Vehicles, IEEE,

Power Electronics, vol, pp.301-308

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