Chapter 3
Supplementary Components and Systems
“Introduction to Modern Power Electronics”, 2nd Ed., John Wiley 2010by
Andrzej M. Trzynadlowski
Chapter 3 2
Driver for an SCR with transformer isolation
Fig. 3.1
SCR
PTR
D2
D1
DZ
(+)
TRA
Chapter 3 3
Optically isolated driver for an SCR
Fig. 3.2
SCR
LED
LAT
OPTO-COUPLER
Chapter 3 4
Non-isolated driver for a triac
Fig. 3.3
TR IA C
(+ )
TRA
Chapter 3 5
Optically isolated driver for a triac
Fig. 3.4
TRIAC
LAT
OPTO-COUPLER
R
LED
Chapter 3 6
Driver for a GTO with transformer isolation
Fig. 3.5
SCR
PTR
DZ
RCT
GT O
M1 M2
LC
(+)
Chapter 3 7
Non-isolated drivers for a BJT: (a) single-transistor driver, (b) driver with a class B output stage
Fig. 3.6
TR
BJT
TR
BJT
TR
TR
1
2
3
C
(a ) (b )
C
(+)(+)
(-)
(-)
Chapter 3 8
Antisaturation Baker’s clamp for a BJT
Fig. 3.7
D4
D0
D1 D2 D3
Chapter 3 9
Driver for a BJT with transformer isolation
Fig. 3.8
(+)
(-)
BJT
T R
T R 1
2
P T R
Chapter 3 10
Driver for a BJT with transformer isolation
Fig. 3.9
(+)
(+ ) (+)
(+)
BJT
(+ )
(-)
(a)
(b)
Bi
ON
OFF
t
Chapter 3 11
Gate drive for a power MOSFET with a high-current TTL clock driver
Fig. 3.10
MOSFET
CD
(+)
Chapter 3 12
Driver for a power MOSFET with transformer isolation
Fig. 3.11
MOSFET
PTR
AM
D
Chapter 3 13
Driver for a power MOSFET with optical isolation
Fig. 3.12
( -)
(+ ) (+ )
AMP L
M O S F E T
( -)
(+ )
(+ )
(-)
Chapter 3 14
SCR crowbar for overcurrent protection of a power electronic converter
Fig. 3.13
SOURC ESUPPLY
CIRCUITCONTROL
CONVERTERAND LOAD
SCR
(+ )
(-)
R
Chapter 3 15
Totem-pole arrangement of two switches in a leg of a bridge topology
Fig. 3.14
R
(+ )
(- )
Chapter 3 16
BJT-based chopper with an RC snubber: (a) circuit diagram, (b) equivalent circuit in the off state
Fig. 3.15
i
vL
i L
V i
snR C sn
vCE
BJT
ii
vo IoD
(a )
i
vL
i L
V i
snR C sn
vCE ii
vo I
(b )
o - i iIo
Chapter 3 17
Voltage and current waveforms in the chopper of Fig. 3.15: (a) without snubber, (b) with snubber
Fig. 3.16
Io
VCE,piC0
Io ii
0 t0
vCE
(b)
Vi
t
VCE,p
0 t0
(a)
=
vCE
0
iC iit
Vi
Chapter 3 18
Switching trajectories of the BJT of Fig. 3.15: chopper iof Fig. 3.15: (a) without snubber, (b) with snubber
Fig. 3.17
Vi
SOA
Io
iC
vCE0
0 VCE,p
VCE,p
(a)0
Io
(b)
SOA
vCEVi
0
iC
Chapter 3 19
Snubbers for: (a) power diode, (b) SCR
Fig. 3.18
(a ) (b )
Chapter 3 20
GTO with turn-on and turn-off snubbers
Fig. 3.19
TUR N -O F FS N U B B E R
TUR N -O NS N U B B E R
i
i
i
v
Chapter 3 21
Combined on-and-off snubber for a transistor
Fig. 3.20
ii
iC
v CE
Chapter 3 22
Snubber for transistors in bridge converters: (a) RC, (b) RCD, (c) charge and discharge RCD, (d) discharge-suppressing RCD
Fig. 3.21
(a) (b)
(c) (d)
Chapter 3 23
Turn-off capacitive snubber with passive energy recovery
Fig. 3.22
Chapter 3 24
Turn-off capacitive snubber for a GTO with active energy recovery
Fig 3.23
Chapter 3 25
TABLE 3.1 Comparison of Thermal and Electrical Quantities
______________________________________________________________________________
Thermal Quantity Electrical Quantity ______________________________________________________________________________
Amount of heat (energy), Q (J) Electric charge, Q (C)
Heat current (power), P (W) Electric current, I (A)
Temperature, Θ (oK) Electric voltage, V (V)
Thermal resistance, RΘ (oK/W) Electric resistance, R (Ω)
Thermal capacity, CΘ (J/ oK) Electric capacitance, C (F)
Thermal time constant, 𝜏Θ = 𝑅Θ𝐶Θ (s) Electrical time constant, 𝜏= 𝑅𝐶 (s)
______________________________________________________________________________
Chapter 3 26
Power diode with a heat sink: (a) physical arrangement, (b) thermal equivalent circuit
Fig. 3.24
HEAT SINK
CAB LE
SEM ICO NDU CTOR
O
R S A
OR C S
OR J C
OC S
OC C
OC J
O J
O A
(a ) (b )
CASE WAF ER
P
O C
O S
l
Chapter 3 27
Block diagram of an adjustable-speed ac drive
Fig. 3.25
MO TO RIN VER TE R
C O N TR O L LERD S P
S Y S TE M RE FE RE NC ES PE E D S IGNA L
C URRE NT S IGNA LS
C URRE NTS ENS ORS
S PE E D S E NS OR
REF ERE NC E C URRENT SIGNALS
S PE E D S IGNA L
(+ )
(- )
C R A
C R
C R
B
C
LOAD