Presented by Won-yong SungEnergy Mechatronics Lab.School of Information and Communication Eng.Sungkyunkwan Universityhttp://seml.skku.ac.kr
DC-DC Converter(II)
(Buck-Boost & Cuk)
전기기기 컴퓨터제어
March. 24. 2011
Sungkyunkwan Univ., Energy Mechatronics Lab.
2
Buck-Boost Converter
Vi
Vs
VD
D
L VL C
isiL
ioic
iD
VOLoad
Step-Down Step-Up Step-Down/Up
Sungkyunkwan Univ., Energy Mechatronics Lab.
3
Vi
Vs
VD
D
L VL C
isiL
ioic
iD
VO
Mode Analysis - 1
0 ≤ < DTSwitch on, Diode off
-
Inductor current increases
-
Diode Voltage
-
, 0s L Di i i
D i Ov v v
Buck-Boost Converter(CCM Analy-sis)
DT T
vS
t
Vi+Vo
vD
tDT T
iD
t
Imax
Imin
DT T
iSImax
Imin
tDT T
iL
t
Imax
Imin
DT T
vL
DT Tt
-Vo
Vi
Vi+Vo
min0
1)( IdtVL
tit
iL
Sungkyunkwan Univ., Energy Mechatronics Lab.
4
Vi
Vs
VD
D
L VL C
isiL
ioic
iD
VO
Mode Analysis - 2
DT ≤ < TSwitch off, Diode on
-
Inductor current decreases
-
Switch Voltage
-
D Li i
s iv v
DT T
vS
t
Vi+Vo
vD
tDT T
iD
t
Imax
Imin
DT T
iSImax
Imin
tDT T
iL
t
Imax
Imin
DT T
vL
DT Tt
-Vo
Vi
Vi+Vo
max0 )(1)( IdtvL
tit
DTL
Buck-Boost Converter(CCM Analy-sis)
Sungkyunkwan Univ., Energy Mechatronics Lab.
5
)1( DVDTV oi
10
8
4
2
0
Gv
0.2 0.4
6
0.6 0.8 1D
Buck Mode Boost Mode
0( ) (1 ) 0L i
Based on Inductor Volt Sec BalanceV V DT V D T
)1(0
DD
VVG
iV
vL
DT T
-Vo
Vi
t
Buck-Boost Converter(CCM Analy-sis)
Sungkyunkwan Univ., Energy Mechatronics Lab.
6
Vi
Vs
VD
D
L VL C
isiL
ioic
iD
VO
Inductor Current Analysis
Vi
Vs
VD
D
L VL C
isiL
ioic
iD
VOminmax ∫)( IdtVLDTtiI DT
iL +1=== 0
maxmin ∫ )-()( IdtvLTtiI TDTL +1=== 0
DTLVII i minmax
TDLVII )-(- minmax 1•= 0
dtdiLv L
L LV
dtdi iL
min0
1)( IdtVL
tit
iL
0vvL Lv
dtdiL 0
max0 )(1)( IdtvL
tit
DTL
Buck-Boost Converter(CCM Analy-sis)
Sungkyunkwan Univ., Energy Mechatronics Lab.
7
iD
t
Imax
Imin
DT T
iSImax
Imin
tDT T
iL
t
Imax
Imin
DT T
iD
t
Imax
Imin
DT T
iSImax
Imin
tDT T
iL
t
Imax
Imin
DT T
2minmax IIIL
LiLi
siin
IVDT
DTIV
IVP
RDVD
RV
IVP
i
2
220
000
)1()(
)1(
)1()1(0
02
DI
DRV
DRVDI i
L
TL
VDI
DTL
VII
L
iL
2)1(
20
max
TL
VDI
DTL
VII
L
iL
2)1(
20
min
siin iVp
Inductor Current Analysis
Buck-Boost Converter(CCM Analy-sis)
Sungkyunkwan Univ., Energy Mechatronics Lab.
8
iD
t
Imax
Imin
DT T
Io=Vo/R
DT T
iC
t-Io
Io
tDT T
vC-Vo
Δvo
)1
1
0
00
/R(VDTC
IDTC
Δv
RVIi 0
00
RVii DC0
Capacitor Voltage Analysis
Buck-Boost Converter(CCM Analy-sis)
𝐶=𝐷𝑇𝑅
𝑉 𝑜
∆𝑣𝑜= 𝐷𝑅 𝑓 𝑠𝑤
1𝑅𝐹
Sungkyunkwan Univ., Energy Mechatronics Lab.
9
: CCM
Buck-Boost ConverterBoundary Conduction Mode
20
00
0max
)1(2
)1()1(2
22)1(
DLTVI
DID
LTVI
IL
TVDII
oB
LB
LL
LTVI
LTVI
oB
LB
2
20
max,
0max,
Sungkyunkwan Univ., Energy Mechatronics Lab.
10
Buck-Boost Converter
DDD
VVG
AiV
0
TD
DTAL
A
IdtvL
TDti 0)(1)( max0
0
max
TVLIDDA )(
2max
0 DDII A 0
02TVLIDDA
Discontinuous Conduction Mode
Based on Inductor Volt Sec Balance
Sungkyunkwan Univ., Energy Mechatronics Lab.
11
Buck-Boost ConverterSimulation
𝐿≥ 𝑅2 𝑓 𝑠𝑤
(1−𝐷 )2= 102×5000
(0.8 )2=640𝑢𝐹
Sungkyunkwan Univ., Energy Mechatronics Lab.
12
Buck-Boost ConverterSimulation
L=1280uF>640uF=> CCM
L=640uF=640uF=> BCM
L=320uF<640uF=> DCM
Sungkyunkwan Univ., Energy Mechatronics Lab.
13
Cuk Converter
Buck-Boost 와 마찬가지로 출력전압의 승압과 강압이 모두 가능
+ v L1 -
i C1
-V o
+
S
L1 C1
C2
+ v s
-+ v C1 -
i L2i L1
i D1
- vL2 +
D
L2
Vi
i o
i c
-V d
+
i s
Sungkyunkwan Univ., Energy Mechatronics Lab.
14
C
+ v L1 -
-V o
+
L1 C1
+ v s
-
+ v C1 -
i L2i L1
i D1
- vL2 +
D
L2i C1=i L1
SVi
i o
i c
-V d
+
i s
Switch off, Diode on
Inductor current decrease
Capacitor is discharged electric-
ity
Cuk Converter
① Switch OFF / Diode ON0
off
onVin
t
vL1
0off
ont
vL2
(Vin-VC1=-Vo)
VC1-Vo
-Vo
0 t
iL1
IL1
0 t
iL2
IL2
(1-D)Ts(=toff)
DTs(=ton)
Mode Analysis - 1
Sungkyunkwan Univ., Energy Mechatronics Lab.
15
CS
+ v L1 -
i C1=-i L2
-V o
+
L1 C
+ v s
-
+ v C1 -
i L2i L1
- vL2 +
L2
DVi
i o
i c
i D1
-V d
+
i s
Cuk Converter
② Switch ON / Diode OFF
Switch on, Diode off
Inductor current increase
Capacitor charges electricity
0off
onVin
t
vL1
0off
ont
vL2
(Vin-VC1=-Vo)
VC1-Vo
-Vo
0 t
iL1
IL1
0 t
iL2
IL2
(1-D)Ts(=toff)
DTs(=ton)
Mode Analysis - 2
Sungkyunkwan Univ., Energy Mechatronics Lab.
16
10
8
4
2
0
Gv
0.2 0.4
6
0.6 0.8 1D
Buck Mode Boost Mode
Cuk Converter
Based on Inductor Volt Sec Balance=0=0
0off
onVin
0off
on
vL2
(Vin-VC1=-Vo)
VC1-Vo
-Vo
t
vL1
t
(1-D)Ts(=toff)
DTs(=ton)
(1-D)Ts(=toff)
DTs(=ton)
01 VVV iC
iC VD
DDVV
110
Sungkyunkwan Univ., Energy Mechatronics Lab.
17
Inductor Current
Cuk Converter
CS
+ v L1 -
i C1=-i L2
-V o
+
L1 C
+ v s
-
+ v C1 -
i L2i L1
- vL2 +
L2
DVi
i o
i c
i D1
-V d
+
i s
DTt 0
dtdiLv L
L1
11
1
1
LV
dtdi iL
1min01
11)( IdtVL
tit
iL
1min01
11max1)( IdtVL
DTtiiDT
iL
DTLVII i 1
1min1max
0 t
iL1
IL1
0off
onVin
vL1
(Vin-VC=-Vo)
(1-D)Ts(=toff)
DTs(=ton)
t
Sungkyunkwan Univ., Energy Mechatronics Lab.
18
Inductor Current
Cuk Converter
C
+ v L1 -
-V o
+
L1 C1
+ v s
-
+ v C1 -
i L2i L1
i D1
- vL2 +
D
L2i C1=i L1
SVi
i o
i c
-V d
+
i s
TtDT
11 CiL vVv
1
11
LvV
dtdi CiL
t
DTciL IdtvV
Lti 1max1
11 )(1)(
1max11
11min )(1)( IdtvVL
TtiIT
DTCiL TD
LVVII Ci )1(1
11max1min
21min1max
1IIIL
DTL
VII iL
111max 2
DTL
VII iL
111min 2
0 t
iL1
IL1
0off
onVin
vL1
(Vin-VC=-Vo)
(1-D)Ts(=toff)
DTs(=ton)
t
Sungkyunkwan Univ., Energy Mechatronics Lab.
19
Inductor Current
Cuk Converter
CS
+ v L1 -
i C1=-i L2
-V o
+
L1 C
+ v s
-
+ v C1 -
i L2i L1
- vL2 +
L2
DVi
i o
i c
i D1
-V d
+
i s
DTt 0
dtdiLv L
L2
22
2
012
Lvv
dtdi CL
t
CL IdtvvL
ti0
2min012
2 )(1)(
2min0
012
22max
)(1
)(
IdtVVL
DTtiIDT
C
L
DTL
VVII C
2
012min2max
0off
on
vL2 VC1-Vo
0 t
iL2
IL2
(1-D)Ts(=toff)
DTs(=ton)
t
-Vo
Sungkyunkwan Univ., Energy Mechatronics Lab.
20
Inductor Current
Cuk Converter
C
+ v L1 -
-V o
+
L1 C1
+ v s
-
+ v C1 -
i L2i L1
i D1
- vL2 +
D
L2i C1=i L1
SVi
i o
i c
-V d
+
i s
0off
on
vL2 VC1-Vo
0 t
iL2
IL2
(1-D)Ts(=toff)
DTs(=ton)
t
-Vo
TtDT
22min2max
2IIIL
RV
DD
RVII
i
L
10
02
DTL
VI
TDL
VII
iL
L
22
2
022max
2
)1(2
DTL
VI
TDL
VII
iL
L
22
2
022min
2
)1(2
Sungkyunkwan Univ., Energy Mechatronics Lab.
21
Capacitor Voltage
+ v L1 -
i C1
-V o
+
S
L1 C1
C2
+ v s
-
+ v C1 -
i L2i L1
i D1
- vL2 +
D
L2
Vi
i o
i c-
V d +
i s
iC1
t
Imax1
Imin1
- Imax2- Imin2
DT T
vC1 – VC1
ΔvC1 t
t
11
1 )1(1LC ITD
Cv
Cuk Converter
Sungkyunkwan Univ., Energy Mechatronics Lab.
22
Capacitor Voltage
+ v L1 -
i C1
-V o
+
S
L1 C1
C2
+ v s
-
+ v C1 -
i L2i L1
i D1
- vL2 +
D
L2
Vi
i o
i c-
V d +
i s
t
iC2
(Imax2 – Imin2)12
(Imax2 – Imin2)12
t
vC2 - Vo
Δvo
DT
DT
T
T
Rvi 0
0
RVIi 0
00
dtdvCiC
022
81
22211
2
2min2max2
2min2max
20
T)I(IC
TIIC
Δv
22
2
2
2
0
20
8
8)1(1
CLTDV
TDLV
Cv
i
Cuk Converter
Sungkyunkwan Univ., Energy Mechatronics Lab.
23
Simulation
Cuk Converter
Sungkyunkwan Univ., Energy Mechatronics Lab.
24
Simulation
Cuk Converter