Transcript Document

Quiz
The periodic waveform below represents the filter inductor current in
a push-pull converter, whose output voltage is regulated to 12 volts.
1. What is the value of the inductor in microhenries?
2. What is the operating frequency of the converter?
3. Sketch the voltage waveform at the input of the filter inductor.
IL
VL T
T
 L  VL
L
I
2.5 mS
  12 v 
 4.3 m H
7 A
46.0 A
I 
42.5 A
39.0 A
fs 
1
1

 40 Khz
Ts 25 mS
I
7A
 4.3 m H
T
10 mS
 3 v  VIN  VOUT
VL  L
VIN  15 v
10.0 mS
12.5 mS
Thyristor (SCR) Converters
Direct power control in Utility Applications at High Power Levels
P
N
P
N
Silicon
Controlled
Rectifier
“SCR”
Half Wave Rectification
vload
VDC 

V pk
2
V pk

sin tdt

2 
1  cos  
Trigger pulses delayed from zero
crossing by “Commutation Angle” 
Full Wave Rectified Voltage
Thyristor “turns off ”when current
goes to zero
Resulting current to resistive Load

Vpk

1  cos 
Resistive Load With Inductance
iload
vload
AC Power Control (Triac)
vload
VL2, rms

2
V
 sin  cos    
pk
2

sin

t
d

t

1
 



 
2 


Vpk2
VL, rms  Vrms 1 
sin  cos   

AC Power Control
1.2
Vout , rms
1
Vin , rms
 Vout , rms 


V
 in , rms 
0.8
0.6
0.4
0.2
0
0
30
60

90
120
150
180
2