The document discusses different types of rectifiers that are used to convert alternating current to direct current. It describes rectifiers as either uncontrolled, using diodes, or controlled, using thyristors. Controlled rectifiers are further classified based on their input supply, quadrant of operation, and number of pulses. Examples of applications for rectifiers include motor speed control, inverters, electrochemical processes, and HVDC transmission. The document provides details on the operation and waveforms of single phase and three phase half wave and full wave rectifiers with resistive and inductive loads.

1. PHASE CONTROLLED RECTIFIERS
• RECTIFIERS CONVERT AC TO DC
• CLASSIFIED AS
– UNCONTROLLED - DIODES ARED USED
– CONTROLLED - THYRISTORS ARE USED
1

2. CLASSIFICATION OF RECTIFIERS
• BASED ON INPUT SUPPLY
– SINGLE PHASE
– THREE PHASE
• BASED ON QUADRANT OPERATION
– 1 QUADRANT
– 2 QUADRANT
– 4 QUADRANT
• BASED ON NO. OF PULSES
– ONE PULSE
– TWO PULSES
– THREE PULSES
– SIX PULSES
2

3. APPLICATIONS OF RECTIFIERS
• DC MOTOR SPEED CONTROL
• DC SUPPLY FOR INVERTERS
• ELECTROCHEMICAL PROCESSES
• DC TRACTION
• HVDC TRANSMISSION
3

4. RECTIFIERS
• SINGLE PHASE HALF WAVE RECTIFIER WITH
R,RL,RLE LOAD
• SINGLE PHASE FULL WAVE RECTIFIER WITH
R ,RL, RLE LOAD
• THREE PHASE HALF WAVE RECTIFIER WITH
R,RL LOAD
• THREE PHASE FULL WAVE RECTIFIER WITH
R,RL LOAD
4

5. SINGLE PHASE HWR WITH R LOAD
5

6. FIRING ANGLE α
• ANGLE BETWEEN THE ZERO CROSSING OF THE
INPUT VOLTAGE AND THE INSTANT THYRISTOR
IS FIRED.
6

7. AVERAGE OUTPUT VOLTAGE OF
SINGLE PHASE HWR WITH R LOAD
7

8. RMS OUTPUT VOLTAGE OF SINGLE
PHASE HWR WITH R LOAD
8

9. PRINCIPAL TOPOLOGIES OF
PHASE CONTROLLED RECTIFIERS
9

10. SINGLE PHASE HWR WITH RL LOAD
10

11. WAVEFORMS OF HWR SINGLE PHASE
WITH RL LOAD
11

12. SINGLE PHASE HWR WITH RL LOAD
AND FD
12

13. WAVEFORMS OF SINGLE PHASE HWR
WITH RL LOAD AND FD
13

14. ADVANTAGES OF USING FREEWHEELING DIODE
• INPUT POWER FACTOR IS IMPROVED
• LOAD CURRENT WAVEFORM IS IMPROVED AND
LOAD PERFORMANCE IS BETTER.
MAIN FUNCTIONS OF FWD
• IT PREVENTS THE REVERSAL OF LOAD VOLTAGE
EXCEPT FOR A SMALL VOLTAGE DROP
• IT TRANSFERS THE LOAD CURRENT AWAY FROM
THE MAIN RECTIFIER THEREBY ALLOWING ALL
THE THYRISTORS TO REGAIN THEIR BLOCKING
STATES
14

15. SINGLE PHASE HWR WITH RLE LOAD
15

16. WAVEFORMS OF SINGLE PHASE HWR
WITH RLE LOAD
16

17. SINGLE PHASE FULL WAVE CONVERTER WITH RL LOAD
AND ITS EQUIVALENT CIRCUIT
17

18. FULL WAVE RECTIFIER
18

19. FULL WAVE RECTIFIER WITH R LOAD
19

20. OPERATION OF FWR WITH RL LOAD
20

21. WAVEFORMS OF FULL WAVE MID-
POINT CONVERTER WITH RL LOAD
21

22. SINGLE PHASE FULL WAVE CONTROLLED
BRIDGE RECTIFIER WITH R LOAD
22

23. THREE PHASE CONTROLLED RECTIFIERS
• ADVANTAGES
– REDUCED RIPPLE CONTENT IN THE OUTPUT
VOLTAGE
– CAN BE USED FOR HIGH POWER APPLICATIONS
• TYPES
– THREE PULSE CONVERTERS
– SIX PULSE CONVERTERS
– TWELVE PULSE CONVERTERS (HIGHER THE NO.OF
PULSES, SMOOTHER IS THE OUTPUT VOLTAGE)
23

24. THREE PHASE HALF WAVE RECTIFIER WITH R LOAD
24

25. WAVEFORMS OF THREE PHASE HWR WITH R LOAD
25

26. THREE PHASE HWR WITH RL LOAD
26

27. WAVEFORMS OF THREE PHASE HWR
WITH RL LOAD (α=00)
27

28. WAVEFORMS OF THREE PHASE HWR
WITH RL LOAD (α=450)
28

29. WAVEFORMS OF THREE PHASE HWR
WITH RL LOAD (α=900)
29

30. THREE PHASE HALF WAVE CONTROLLED
RECTIFIER WITH R LOAD
30

31. THREE- PHASE HALF WAVE CONTROLLED
RECTIFIER
Three- phase half- wave controlled rectifier
Resistive load, α= 0º
a
b
c
T
R
ud
id
VT2
VT1
VT3
u2
O
O
O
uab uac
O
iVT1
uVT1
 t
 t
 t
 t
 t
u a u b u c
u G
u d
 t1  t2  t3
Common-cathode connection
Natural commutation point
31

32. Resistive load, α= 30º
u2
ua ub uc
O
O
O t
O
t
O
t
uG
ud
uab uac
t1
iVT1
uVT1 uac
t
t
a
b
c
T
R
ud
id
VT2
VT1
VT3
32