8/10/2019 048-12-Feb-09.doc

1/5

Study and Simulation of One Bi-directional DC/DC Converter in HybridElectric Vehicle

Jian-ming HU uan-rui CHE! "i-#uan ang

Electric $o%er College& South China Univer'ity of (echnology& )uang*hou& )uangdong)uangdong +ey laboratory of clean energy technology& )uang*hou& )uangdong&

E-mail, hu#ianming .. 01 23com Abstract - The paper first introduces the basic drive systemof a kind of hybrid electric vehicle. It demands high powerbidirectional flow capability, with wide input voltage range,and output voltage of energy storage devices such as supercapacitors or batteries vary with the change in load. Then theselection and design of aforementioned converter is proposedin this paper. The converter which is like a half bridgetopology, has high power flow capability and minimumdevice stresses that can suitably interface a super capacitorwith the drive train of a hybrid electric vehicle. Furthermore,by comparing of the main characteristics and applicationswith some typical isolated bidirectional D !D converter, the

proposed converter has low device rating and can becontrolled by duty cycle and phase shift. At last, the mostimportant characteristics of this converter is that it uses thetransformer leakage inductance as the primary energytransfer element and control parameters, "imulationwaveforms based on "I#etri$ are given to demonstrate thegoodness of this novel topology, and this converter is alsosuitable for high power application, in particular forcontrolling the charge-discharge of super capacitors orbatteries that can be used in hybrid electric vehicle.

%eywords& bi-directional D !D converter, hybrid electricvehicle, circuit structure

43 4 !(5ODUC(4O!

4n recent year'& HEV 6Hybrid Electric Vehicle'7 ha'attracted more and more attention' of many countrie'8vehicle indu'try3 9utomobile' :o%ered by internalcombu'tion engine' re:re'ent a huge infra'tructureinve'tment& and about one third oil con'um:tion3 So thetran'ition to an all-electric mobile fleet a::ear' to be veryattractive and de'irable& but ha' been limited by 'everal+ey technology and bu'ine'' i''ue' ;1

8/10/2019 048-12-Feb-09.doc

2/5

=urthermore& in order to ma+e com:lete the in'tantaneou' :o%er out:ut of battery& %e utili*e bi-directional converter to %or+ %ith 'u:er ca:acitor to increa'e in'tantaneou'

:o%er out:ut& and im:rove the acceleration anddeceleration of hybrid vehicle3

(o 'ummari*e %hat %e have di'cu''ed& the bi-directional converter mu't have high energy utili*ation3 Soit 'ugge't' the need for i'olated bi-directional DC/DCconverter'3

9 'im:li'tic a::roach %ould u'e t%o full bridgeDC/DC converter' to im:lement the bi-directional :o%er flo% re uired3 Ho%ever& reali'tic im:lementation' %ouldneed to contend %ith '%itching lo''e' to deal %ith dioderever'e recovery and energy tra::ed in the tran'former lea+age inductance3 (he full bridge converter %hich i''ho%n in fig3 u'e' '%itche' and :re'ent' a minimalto:ology that i' 'uitable for high-:o%er den'ity& effectiveu'e of 'y'tem :ara'itic& "VS o:eration& and fa't control3Ho%ever& %hen o:eration over a %ider ,1 voltage rangei' re uired& device 'tre''e' become very high ;?:and "VS range andin:ut voltage3 =ig3 2 'ho%' the ideali*ed %aveform' of thene% half bridge converter3

4t i' 'een that %hen the condition V 1=N*V 3 and V in = N*V 4 i' 'ati'fied& the current %aveform i' Iflat to::edF&re'ulting in minimal current 'tre''e'& and an o:timal :oint3

=ig3 2 A 4deali*ed %aveform' of tran'former :rimary 'idevoltage& 'econdary 'ide voltage and tran'former current

8/10/2019 048-12-Feb-09.doc

3/5

=rom e uation 617 %e can 'ee that the out:ut :o%er i'regulated by controlling duty cycle 6 D7 of '%itche' and the

:ha'e 'hift angle 6 73

.

1t 6 t7o ab L P V i d t

=

?in

k

V D L D D

= 4 -1- 1- 617

Before %e analy*e the :rinci:le o:eration of the converter&%e 'hould ma+e 'ome a''um:tion3

(he converter i' %or+ing on a 'tate 'table9ll the '%itche' of converter are ideal '%itchingdevice& and in :arallel %ith ca:acitor and diode&%hich i' on the in'ide3(he inductor Llk i' 'um of the tran'formerF' lea+ageinductor and an e>tra inductor(he inductor 6 Lm7 of e>citing coil i' large enough& 'othe magneti*ing current can be 'mall enough(he e uali*ing ca:acitor C1~C3 are large enough& 'oa' to get a le'' voltage ri::le3

(he duty cycle of 1 and 2 i' D& and the duty cycleof 3 and 4 i' 1!D 3 4n u: mode& energy i' ta+en fromthe battery and ca:acitor to the DC bu'& 'o the driving'ignal of 1 and 2 mu't before the driving 'ignal of 3and 4 3 hile in do%n mode& energy flo% from DC bu'to the battery and ca:acitor3 (he only difference i' thedriving 'ignal of 1~ 4 3 (he o:eration of do%n mode i''ame %ith the u: mode& 'o %e only tal+ about the u:mode3 4n order to ea'y the analy'i' of converter circuit& thetran'formation ratio i' defined a' one& 'o the voltage of Vcd can be in'tead of V2 and V33 =igure K 'ho%' the e>act%aveform of inductor current and the voltage in the 'ideof it3 (he '%itch cycle i' divided into 1 :art'& %hich aret.@t1 & it 'ho%' the e>act time of four '%itche' %hen theyare o:ening and %hen they are clo'ing3 =or e>am:le& the'%itch 1 i' clo'ing in time of t1& and the '%itch 2 i'o:ening bet%een the time t2 and t33

=ig3 K A aveform' and time diagram for bi-directionalconverter in u: mode

4n fig3 K& the :ro:o'ed to:ology ha' the advantage' of 'oft A '%itching im:lementation %ithout additionaldevice'& and it i' controlled by duty cycle and :ha'e 'hift3=ig3 K only 'ho%' the time %hen the'e '%itche' areo:ening or clo'ing& but not 'ho%' the condition for themto o:en or clo'e3 =rom fig3 K& in u: mode& theim:lementation of 'oft A '%itching %ith converter i'relevant to the :rimary current 'tate before the '%itche'are clo'ing3 E uation 6 7 @ 6 7 'ho%' the condition of current in different time& and Lk i i' the current of the

lea+age inductance& Ldci i' the current of the in:utinductor3

6 17 6 17 Lk Ldci t i t >

6 7 . Lk i t < 6 K7 6 17 Lk Ldci t i t

627

637

647

657

E uation 627 'ho%' ho% to calculate the current 6 Lk i 73

. .

1 1 1"

" D"

Lk Lk Lk "

i dt i dt i dt " " "

= + +

1 1

" " D"

Lk Lk " D" D"

i dt i dt " "

+

+

+ 627

=ig3 K 'ho%' the %aveform and time diagram of four '%itche' and diode'3 Both figure K and e uation 627 areutili*ed to derive the e uation' of current in each device3(he switch voltage stress i' V in # $1 D%& it 'ho%' the'%itche' have the 'ame :ea+ voltage& ho%ever& the current'tre'' i' different from each other3 E uation' 6K7 and 6 7'ho% the current 'tre'' of 1 ~ 4 %hen the converter i'%or+ing in u: mode3

1

L L LL

L L LL L61 7 ? 61 7

in in

lk dc

in in

lk lk

V V D "s I I

L L

V D V L D D L

= = +

+

peak peak

6K7

HD H? :ea+

L L LM 6 & 7

L L61 7 Lin in

lk lk

V D V I I a'

L D L

=

peak 6 7

=ig3 'ho%' the %hole circuit of bi-directionalconverter %hen it i' %or+ing in u: mode3 4t u'e'tran'former lea+age inductance a' the :rimary energytran'fer element3 9 bloc+ ca:acitor Cb i' in 'erie' %ith the

:rimary %inding of the tran'former to ma+e the :rimarycurrent to reduce to *ero during *ero 'tate3 (he averagevoltage acro'' Cb e ual' to be *ero in one '%itching

:eriod in 'teady 'tate& limiting the re uired Cb rating3E uation 6N7 'ho%' the ma>imal current of bloc+ ca:acitor3

8/10/2019 048-12-Feb-09.doc

4/5

L L LL

L L LL L61 7 ? 61 7

in inCb

lk dc

in in

lk lk

V V D "s I

L L

V D V L D D L

= +

+

6N7

=ig3 A (he circuit to:ology of bi-directional DC/DC converter %or+ in u: mode

4443 S4 UG9(4O! 9!D E $E54 E!(9G5ESUG(S

O:erating :rinci:le %a' verified in 'imulation i' u'ingS4 etri>3 =or the reali'tic 'imulation of HEV a::lication&

the condition' and :arameter' for the 'imulation %ere thefollo%ing value', sourceV = ? V& out V M 1..V& o P M

1... & (o M K & the :ha'e i' .& ) M .PH*& k L M

uH& dc L M.3 mH =ig3 N 'ho%' the %aveform' of abV &

sV and Lk i %hen in:ut 'ource voltage i' ? V3

Q 1 - D / V

T X 1 - 2 0 / V

P r o b e 4 - N

O D E / V

T X 1 - 1 1 / V

.

.

.

.

i i

. . . . .

# $ % 2 - P & / '

)

i

=ig3 N A aveform' of abV sV and Lk i %hen sourceV M? V

=ig3 1. A aveform' of sV and abV in the initial 'tage of 'imulation

=ig3 11- aveform' of '%itch 6 1 7 %hen sourceV M? V

Q 1 - D / V

.

.

.

# $ % 2 - P & / '

T X 1 - 2 0 / V

i i

. . . . . . . P r o

b e 4 - N O D E / V

=ig31 A aveform' of abV sV and Lk i %hen sourceV M 2V

4V3 CO!CGUS4O!

4n the :a:er& a ne% ty:e half bridge DC/DC converter i' :ro:o'ed for hybrid electric vehicle& %hich ha' minimum'%itche' 'tre'' for %ide range of 'ource voltageo:eration3(he converter u'e' $ :lu' :ha'e-'hiftcontrol to achieve 'oft-'%itching3 (he to:ology i' 'uitablefor high :o%er a::lication& e':ecially for controlling the

battery of 'u:er ca:acitor that can be u'ed in hybridelectric vehicle3 Simulation %aveform' ba'ed on S4 etri>are given to demon'trate the goodne'' of the to:ology3

5 E=E5E!CES;1< H3 Gi& =3 "3 $eng& and J3 S3 Ga%ler& Q9 ne% "VS bi-

directional dc-dc converter for fuel cell and batterya::licationR& 4EEE (ran'3 $o%er Electron3 Vol31N& no31& ::3K& ..2

8/10/2019 048-12-Feb-09.doc

5/5