1 steady-state analysis in dcm boost converter in dcm
TRANSCRIPT
1
Steady-state Analysis in DCM
sDT 1 sDT
0 A
Ss
VDT
L
Li
LV
Di
1 sDT
Ss
VDT
L
0 A
Same area
Bo
ost C
onve
rte
r in
DC
M
2
SV
Li lR
Ci
R OV
Li lR
SVCi
R OV
sDT (1 ) sD T
Effect of Parasitic Resistance
● Volt-sec balance on inductor
● Amp-sec balance on capacitor
Effe
cts
of P
ara
sitic
Re
sist
ance
3
Effect of Parasitic Resistance
0.0 0.2 0.4 0.6 0.8 1.00
1
2
3
4
5
6
D
/ = 0 (Ideal)lR R
0.040.06
0.1
(1 )
(1 )
S L l O
OL
V I R D V
VD I
R
2
11 1
1(1 )(1 )
Ol
S
V RV D RD
/O SV V
D
0.08
/ = 0.02lR R
Effe
cts
of P
ara
sitic
Re
sist
ance
4
Prototype Boost Converter
160 H 0.1
5 470 F
50 kHzSf
12 V OV
0 20 40 60 800
10
20
30
40
50
v O(t
) [V
]
Time [us]
= 0.875D
= 0.900D
= 0.925D
= 0.950D
0.875D
Duty ratio Output voltage
2
2
11 1
11(1 )
11 1 0.1 12 42V11 0.875 5(1 0.875)
lO SRV VD RD
0.900D 40 V35 V0.925D
0.950D 27 V
Effe
cts
of P
ara
sitic
Re
sist
ance
5
Buck/Boost Converter : An Up-Down Dc-to-Dc Converter
● Evolution to Buck/Boost Converter
i) Cascaded connection of buck converter and boost converter
SV
OV
a
SV
OVp
p
a
ii) Alternative representation using SPDT switches
Bu
ck/B
oo
st C
on
vert
er
6
pSV
OV
a
a
p
Buck/Boost Converter : An Up-Down Dc-to-Dc Converter
iii) Non-inverting Buck/Boost converter
SV
Lv OV
Lv OV
iv) Subcircuits of non-inverting Buck/Boost converter
Bu
ck/B
oo
st C
on
vert
er
7
Buck/Boost Converter : An Up-Down Dc-to-Dc Converter
v) Modification of subcircuits
SV Lv
OV
Lv
OV
vi) Buck/Boost converter
Lv
OV
OV
SVSV
Bu
ck/B
oo
st C
on
vert
er
8
Buck/Boost Converter in Steady State
SV Lv
OV
R
Qi Di
Li
Ci
SV Lv
R OV
OV
RLv
Small ripple approximation
Piecewise linear analysis
OV
SV
Bu
ck/B
oo
st C
on
vert
er in
Ste
ady
Sta
te
9
Li
Qi
Di
Ci
acv
maxLi
minLi
maxLi
Li LI
QI
DI
Ci
acv0 V acv
0 A
D OI I SDT
Buck/Boost Converter in Steady StateB
uck
/Bo
ost
Co
nve
rter
in S
tead
y S
tate
10
Buck/Boost Converter in DCM
SV OV
R
Li
0 A
1
2L LI iLi
Li
CCM :
DCM :
Borderline :
Bu
ck/B
oo
st C
on
vert
er in
DC
M
11
Steady-State Analysis in DCM
Ss
VDT
L
0 A
sDT 1 sDT
Li
SV
OV
0 VLv
Di
sDT 1 sDT
Bu
ck/B
oo
st C
on
vert
er in
DC
M
12
Structure of Three Basic Converters
i) Buck converter
ii) Boost converter
iii) Buck/boost converter
Th
ree
Bas
ic P
WM
Co
nve
rter
s
13
Voltage Gain of Three Basic Converters
1.0D
O SV V/
1.0
0
(1)
(2)(3) D
1
1 D
1
D
D
A
B
C
Th
ree
Bas
ic P
WM
Co
nve
rter
s