By: Dr. Shahram Javadi
By: Dr. Shahram Javadi
Department of Electrical Engineering
Sh.javadi@iauctb.ac.ir
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1.
Introduction To Power Electronic
2.
Power Diodes
3.
4.
Thyristors
5.
Control Rectifiers
6.
AC Voltage Controllers
7.
Thyristor Commutation Techniques
8.
Power Transistors
9.
DC to DC Choppers
10.
DC to AC Inverters
By: Dr. Shahram Javadi
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By: Dr. Shahram Javadi
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 Type 1
 DIODES Conduct Automatically when Forward Polarity is Applied.
 Type 2
 THYRISTORS or SCR ’ S - Begin to Conduct in the Forward
Direction Upon Command of a Control Signal and Continue to
Conduct Until the Next Current Zero Crossing.
 Type 3
 TRANSISTORS, GATE CONTROLLED SWITCHES, FORCE-
COMMUTATED THYRISTORS - Forward Conduction can be
Initiated and Interrupted by Control Signals.
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By: Dr. Shahram Javadi

Classification of switches according to their controllability:
 – Uncontrolled: Diode
 – Semi-controlled: Thyristor (SCR)
 – Fully controlled: Power transistors
(e.g. BJT,MOSFET, IGBT, GTO, IGCT)
By: Dr. Shahram Javadi
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“Diode Converters”
A. Single phase half wave.
B. Single phase full wave.
C. Three phase 3 pulse.
D. Three phase bridge
By: Dr. Shahram Javadi
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A. Single phase half wave uncontrolled rectifiers
By: Dr. Shahram Javadi
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B. Single phase uncontrolled full wave rectifiers
By: Dr. Shahram Javadi
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C,D. Three phase uncontrolled rectifiers
By: Dr. Shahram Javadi
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A. Single phase half wave uncontrolled rectifier
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By: Dr. Shahram Javadi

A. Single phase half wave uncontrolled rectifier
By: Dr. Shahram Javadi
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DC load characteristics: Voltage Relationships
 The average value of the load voltage v defined as
L is V dc and it is
 In the case of a half-wave rectifier, the load voltage vL(t)= 0 for the negative half-cycle.
 The root-mean-square (rms) value of load voltage vL is VL, which is defined as
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By: Dr. Shahram Javadi

DC load characteristics: Current Relationships
 The average value of load current i
L is I
R is purely resistive it can be found as dc and because load
 The root-mean-square (rms) value of load current i
L found as can be
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By: Dr. Shahram Javadi

Performance Parameters for half wave uncontrolled rectifier
 Rectification Ratio
 Form Factor
 Ripple Factor
By: Dr. Shahram Javadi
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Performance Parameters for half wave uncontrolled rectifier
 Transformer Utilization Factor
 Harmonic Factor (Total Harmonic Distortion)
 Power Factor
Half Wave PF

P ac
VA

0 .
5 2
0 .
707

0 .
5

0 .
707
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By: Dr. Shahram Javadi

B. Single phase Full wave uncontrolled rectifier
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By: Dr. Shahram Javadi

B. Single phase Full wave uncontrolled Rectifier
By: Dr. Shahram Javadi
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DC Voltage
Performance Parameters for full wave uncontrolled rectifier
DC Current
RMS Current
RMS Voltage
Efficiency
Form factor Ripple Factor
By: Dr. Shahram Javadi
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Performance Parameters for full wave uncontrolled rectifier
 Transformer Utilization Factor
 Harmonic Factor (Total Harmonic Distortion)
 Power Factor
Full Wave PF

P ac
VA

0 .
707
2
2

0 .
707

0 .
5

0 .
707
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By: Dr. Shahram Javadi

By: Dr. Shahram Javadi
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Single phase Full wave
Bridge Rectifier
By: Dr. Shahram Javadi
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Single phase Full wave Rectifier Inductive load
Due to the energy stored in the
Inductance, the diode will continue to conduct after the supply voltage
Crosses the zero mark. The diode stops to conduct at t
3 p
< w t
3
< 2 p where,
By: Dr. Shahram Javadi
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Analysis of the inductive load
A. Calculations of the load current for w t

0 di dt d

R
L i d

V
L m sin w t
Solving for i d for 0
 w t
 w t
3 i d

V m
Z sin( w t
 
)

Ae

Rt
L where,
Z

R 2

( w
L ) 2 and
  tan

1 ( w
L
R
)
At t

0 , i d i d i d

0

A

V m sin

Z

V m
Z

0 sin( at t
3 w t
 
)
 p
< w t
3
V m sin
 e

Rt
L
Z
< 2 p
B. Calculations of dc Voltage
V d

1
T

0
3 t
V m sin( w t ) dt
V d

1
2 p
V m
[
 cos( w t
3
)

1 ]
C. Calculations of dc current
I d

1
3 t
T

0 i d dt
I d


1
2 p
 w t
3

V m
Z




0 sin( w t
 
)
 sin
  e
 w
R
L w t


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By: Dr. Shahram Javadi

Inductive load with free wheeling diode
To release the energy stored in the inductor and restore the average load voltage
Free Wheeling diode is connected in parallel with the load such that it gets turned On when the supply voltage hits the zero mark.
By: Dr. Shahram Javadi
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C. Three phase Full wave Rectifier
By: Dr. Shahram Javadi
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C. Three phase Full wave Rectifier
By: Dr. Shahram Javadi
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