EPEC 2012 OCTOBER 10-12

Modeling and Control of a Cascaded Boost

Converter for a Battery Electric Vehicle

� A. Ndtoungou, Ab. Hamadi, A. Missanda and K. Al-Haddad, Fellow member, IEEE

EPEC 2012 OCTOBER 10-12

contents

�� IntroductionIntroduction

�� Comparison between boost and cascade boostComparison between boost and cascade boost

�� Modeling and control of cascade boost converterModeling and control of cascade boost converter

�� Space average model of the systemSpace average model of the system

�� Control law for output voltage controlControl law for output voltage control

�� Design of the Design of the ProportionalProportional IntegralIntegral (PI) controller(PI) controller

�� Control Scheme of cascade boost for voltage controlControl Scheme of cascade boost for voltage control

�� Simulation resultsSimulation results

�� Control of Battery currentControl of Battery current

�� Simulation resultsSimulation results

�� Cascade boost converter used as non polluting converterCascade boost converter used as non polluting converter

�� Control schemeControl scheme

�� Simulation resultsSimulation results

�� ConclusionConclusion

EPEC 2012 OCTOBER 10-12

� I’s a new modeling technique of a cascade Boost converter;;

� The nonlinear control is applied and gives good performances in grid side

and in dc side.

� PI controller eliminates efficacy the steady state error of the dc bus voltages;

�� TheThe configurationconfiguration proposedproposed maymay bebe usedused toto fastfast chargingcharging electricalelectrical vehiclevehicle

batterybattery byby controllingcontrolling thethe timetime chargingcharging;;

�� TheThe configurationconfiguration connectedconnected toto thethe gridgrid compensatescompensates currentcurrent harmonics,harmonics,

reactivereactive power,power, tthe THD of the grid current is less than 5%.

INTRODUCTION

EPEC 2012 OCTOBER 10-12

Comparison between Boost and cascade Boost

Characteristics of boost converter and cascade boost converter

The boost converter provides high currents, while the cascade boost converter achieves high voltage. The advantage of the high voltage of the cascade boost converter make it verysuitable for high battery voltage charging current.

EPEC 2012 OCTOBER 10-12

Modeling and control of cascade

boost converter

Q

1D

1C

1L

1Li

2Li

2D

3D

1v

inV 2

C R ov

oi2L

inV

1Li

1Lv

2Li

2L

2Lv

1L

1Cv

2Cv

1Ci

1v

2Ci

1C

2C

oi

R ov inV

1Li

1Lv

2Li

2L

2Lv

1L

1Cv

2Cv

1Ci

1v

2Ci

1C

2C

oi

R ov

ON OFF

EPEC 2012 OCTOBER 10-12

Space average model of the system

( )

( )

( )

( )

−= − +

− = −

−= −

−

= −

1

1

2

1

1

1 2

2

L

C in

1 1

L

C 0

2 2

C

L L

1 1

oL o

2 2

di 1 d 1v V

dt L L

di 1 d1v v

dt L L

dv 1 d 1i i

dt C C

1 ddv 1i v

dt C RC

EPEC 2012 OCTOBER 10-12

Control law for output voltage control :

Where :

is the output of the controller PI

is the current in inductance

( )+ = − =2

02 o L

dv 1C v 1 d i u

dt R

= −2L

ud 1

i

u

2Li 2L

The dynamics of the output voltage is given by

The control law is

The right term of this equation which is linear uses PI controller to regulate the voltage v0 and we extract the control law from this equation

EPEC 2012 OCTOBER 10-12

Design of the Proportional Integral

(PI) controller

Closed loop output voltage regulation

The choice of the PI controller is based on the desired performance of The damping factor ζ and pulsation to give best response.

+= + =

p iip

k s kkG(s) k

s s

0refv

0v

p ik s k

s

+

2

R

RC s 1+

u

( )p i0 2

Fp0 2 i

2 2

1k s k

G CG

1 R k1 G ks s

R C C

+

= =++

+ +

( )p i2

F 2 20 0

1k s k

CG

s 2 sξ ω ω

+

=+ +

p

0p 0 22

22ii 0 20

2

1 Rk2 1

k 2 CRCR

kk C

C

ξωξω

ωω

+= = −

⇔ ==

0ω

EPEC 2012 OCTOBER 10-12

Control scheme of cascade boost for voltage

control

0 refv

d u

10

v

L2i

Output voltage

Output reference

voltage is chosen

by user

EPEC 2012 OCTOBER 10-12

Simulation results

Simulation results with cascade boost converter

Simulation results with boost converter

Cascade boost converter is able to

regulate the output voltage

The best choice of inductance L2 can

give iL2 positive

For the high voltage, the boost

converter is not able to regulate the

output voltage

EPEC 2012 OCTOBER 10-12

CONTROL OF BATTERY CURRENT

Control scheme of cascade boost for current control

2D

1D

inV

3D

1C

0i

Q0

v

1Li

2C

2L

2Li

1L

1v

We test the cascade boost converter

to charge the battery and to compare

it with the boost converter

Control law :

( )1

1

11 in

C

d u Vv

= + −

EPEC 2012 OCTOBER 10-12

Simulation results

Simulation results of cascade boost with battery current control

Simulation results of boost with battery current control

The both system gives the same performance to charge the battery

The slight difference is observed in the boost converter that the current flowing in the

inductance presents the high ripple current compared of the cascade boost converter

EPEC 2012 OCTOBER 10-12

CASCADE BOOST CONVERTER USED AS NON POLLUTING

CONVERTER

Cascade boost Spectrum of the grid current

aD

bD

cD

dD

inV Q

1D

1C

1L

1Li

2Li

2D

3D

1v

2C R ov

oi2L

fL

EPEC 2012 OCTOBER 10-12

Reference current : iL1ref

Control Scheme

1

01

0

inL ref v C

in

v Vi u i

V v

= +

Control law

( )1

11 i in

C

d u Vv

= + −eq. 31 eq. 29

EPEC 2012 OCTOBER 10-12

Simulation results

Steady state response of a non polluting converter: upper - voltage and current

source, lower - output voltage

Dynamic response of a non polluting converter: upper- voltage and current source, lower- output voltage and its

reference

Grid current and grid voltage are in phase

The THD of the grid current is less than 5%During the output reference voltage variation we see that the output voltage well regulated , that the grid voltage and the grid current are in phase and sinusoidal

EPEC 2012 OCTOBER 10-12

CONCLUSION

• The modeling of the cascade boost converter and the nonlinearcontrol technique are presented.

• The simulations results have shown good performances of thecascade Boost compared to the classical Boost converter.

• The cascade Boost converter is suitable for high voltage battery.

•The cascade Boost converter used as non polluting convertergives a THD less than 5% in the grid side.

•The control of the battery current will help to control thecharging time which may be used to fast charging electricalvehicle battery.

EPEC 2012 OCTOBER 10-12

THANK YOU

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