Page 291 - Rashid, Power Electronics Handbook

15 Resonant and Soft-Switching Converters 281

ON C
S S
OFF L L
S F
3
I /I D
Lr O S
0 V i D C D V o
-3 BUCK
3
C
I /I D
S O
L L
F
0
D
V D S C V
-3 i S S o
5
4
V /V BOOST
S i 3
2 C
S C
1 D
0 S L
3
2 D D
I /I S
Df O 1 V L V
0 i F o
3
2
V /V BUCK/BOOST
f i 1
0
t t t t t
0 1 2 3 4
L F L C T L F
(a)
ON
S V i D S S C S D C D V o
OFF
5
I /I CUK
Lr O
C
0 S
L C L
S T F
-5
5 D
S
I /I V L D C V
S O i T D o
0
ZETA
-5 C
5 D
V /V 4 L F L C T
S i
3
2 D
1 V D S C L V
0 i S S T o
5
I /I
Df O
SEPIC
0
3 FIGURE 15.17 Use of the multiresonant switch in conventional PWM
V /V 2 converters.
f i
1
0
t t t t t
0 1 2 3 4
(b) two switches. This concept can be illustrated with the buck
FIGURE 15.16 Possible modes of the buck ZVS-MRC: (a) mode I; and converter as shown in Fig. 15.19, together with the gate drive
(b) mode II. waveforms and operating stages. Both S and S are turned on
1 2
during the time when currents ¯ow through the antiparallel
diodes of S and S . This stage ends when S is turned off with
2
2
1
replaced with an active switch S [22]. A constant-frequency ZVS. The ®rst resonant stage is then started. The resonant
2
multiresonant (CF-MR) switch is shown in Fig. 15.18. The circuit is formed by L and C . A second resonant stage
S2
r
output voltage is regulated by controlling the on-time of the begins. Then L resonates with C and C . The voltage across
r
S1
S2