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Voltage and current waveforms in a static dc switch Chapter 63 Fig. 6.2
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Chapter 6
DC-to-DC Converters
“Introduction to Modern Power Electronics”, 2nd Ed., John Wiley 2010by
Andrzej M. Trzynadlowski
Static dc switch based on a fully controlled semiconductor power switch
Chapter 6 2
Fig. 6.1
LO ADSU P PLYSO U R C E
S
D vo
io
i D
i i
V i
Voltage and current waveforms in a static dc switch
Chapter 6 3
Fig. 6.2
0
0
0
0
0
Vi
g
iD
ii
t
t
t
t
io
ONOFFON
t
vo
SCR-based static dc switch with a resonant commutating circuit
Chapter 6 4
Fig. 6.3
v
V
o
L
C
1
2 c
T1
T2
2D
D1
ii
vic
i
i
i
o
i
Subcircut of an SCR-based static dc switch
Chapter 6 5
Fig. 6.4
T1
C
T2
c civ
Voltage and current waveforms in an SCR-based static dc switch
Chapter 6 6
Fig. 6.5
0
0
0
0
0
0
Vi
t
t
g2g1
i2
vc
i1
ic
t
t
t
ONOFFON
t
vo
Step-down chopper: (a) block diagram, (b) equivalent circuit for the dc output voltage and current
Chapter 6 7
Fig. 6.6
R
L
E
R
E
vo o,dcI
Vo,dc
= M V i
i o i i
i V CHOP P ER
First-quadrant chopper
Chapter 6 8
Fig. 6.7
i D
i i
V i
Vo,dc
Io,dc
R
E
LD
S
vo
i o
Equivalent circuits of the first-quadrant chopper: (a) state 1, (b) state 0
Chapter 6 9
Fig. 6.8
io
i i
vo
R
L
E
vo
R
L
E
(b)(a)
V i iD
iS io
Example waveforms of output voltage and current in a first-quadrant chopper
Chapter 6 10
Fig. 6.9
E
Vi
io
vo
M=0.75M=0.50
t 0
Single cycle of the output voltage and current in a first-quadrant chopper
Chapter 6 11
Fig. 6.10
tOFF tON tON
io
Io,dc
io
0
Vivo
+t 0
Current ripple in a chopper as a function of the magnitude control ratio and switching frequency
Chapter 6 12
Fig. 6.11
Second-quadrant chopper
Chapter 6 13
Fig. 6.12
V i
i i
DSi
i o
R
L
E
Vo,dc
o,dcI
S ov
Equivalent circuits of a second-quadrant chopper: (a) state 1, (b) state 0
Chapter 6 14
Fig. 6.13
io
i i
vo
R
L
E
V i
iD
vo
R
L
E
io
(a) (b)
iS
Waveforms of output voltage and current in a second-quadrant chopper
Chapter 6 15
Fig. 6.14
E
Vi
io
vo
M=0.25M=0.50
t 0
First-and-second-quadrant chopper
Chapter 6 16
Fig. 6.15
V i
i i
S1i
D2
D2i
D1i
D1
S2i R
L
E
o,dcoi
Vo,dc
I
S 1
S 2 vo
Waveforms of output voltage and current in a first-and-second-quadrant chopper
Chapter 6 17
Fig. 6.16
E
Vi
io
vo
M=0.75 M=0.25
t 0
First-and-fourth-quadrant chopper
Chapter 6 18
Fig. 6.17
oi R L E
vo
i i
S 1i
V i
D 1
D 2i
D 1i S2i
D 4
o ,dc
Vo,dc
I
S 1
S 4
Equivalent circuits of a first-and-fourth-quadrant chopper operating in the fourth-quadrant: (a) state 2, (b) state 0
Chapter 6 19
Fig. 6.18
io R
vo
L E < 0
iD1 i
S4
i i
R E < 0 io
iD4
V i
iD1
L
vo
(a)
(b )
Waveforms of output voltage and current in a first-and-fourth-quadrant chopper
Chapter 6 20
Fig. 6.19
E
Vi
io
vo
M=0.75 M=0.25
t 0
Four-quadrant chopper
Chapter 6 21
Fig. 6.20
i i
S1i
V i
D 1
D1i
R L E
vo
D2i
S2i
D 4
D2i
S2i
oi
D 2
D 3
i
i
S3
D3
o,dc
Vo,dc
I
S 1
S 2
S 3
S 4
Chapter 6 22
TABLE 6.1 Operating Features of the Four-Quadrant Chopper
______________________________________________________________________________
Quadrant: I II III IV
____________________________________________________________________________________________________________________
E ≥ 0 > 0 ≤ 0 < 0
x1 0, 1, 0, 1,… 0 0 0
x2 0 0, 1, 0, 1,… 1 0
x3 0 0 0, 1, 0, 1,… 0
x4 1 0 0 0, 1, 0, 1,…
ON state 9 4 6 1
OFF state 1 0 4 0
ON circuit S1-D4 S2-D3 S2-S3 S4-D1
OFF circuit S4-D1 D2-D3 S2-D3 D1-D4
vo x1Vi (1 - x1)Vi -x3Vi (x4 – 1)Vi
M d1 1 - d2 - d3 d4 – 1
M range E/Vi to 1 0 to E/Vi -1 to E/Vi E/Vi to 0
______________________________________________________________________________
Allowable ranges of the magnitude control ratio in step-down choppers
Chapter 6 23
Fig. 6.21
M
V i
E
-1
1
1-1
I
II
III
IV
Step-up chopper
Chapter 6 24
Fig. 6.22
i oi i
D
V i
L c
S vo
L
R
E
Waveforms of the output voltage and input current in a step-up chopper (d = 0.75)
Chapter 6 25
Fig. 6.23
ii
Vi
vo
t 0
Typical supply system of a chopper
Chapter 6 26
Fig. 6.24
AC
LIN
E
RECTIFIERDC LINK
LOA
D
CHOPPER
DC drive with a chopper with a braking resistor
Chapter 6 27
Fig. 6.25
R E C TIF IE RD C LIN K
AC
LIN
E
B R A K IN GR E S IS T O R
M O T OR
C H OP P E R
