1. WELCOME TO THE PRESENTATION Dr. S. Narasimha TKRCET By
Professor, Dept of E.E.E
TKRCET

2. PHASE CONTROLLED RECTIFIERS

3. Single-Phase Half-Wave Converter
Average Load Voltage =

4. With Inductive Load
Average value of Load Voltage:

5. Effect of Free Wheeling Diode :
Main Functions :
It prevents reversal of load voltage except
for small diode voltage drop.
It transfers the load current away from the
main rectifier, thereby allowing all of its
thyristors to regain their blocking states.

7. Single-Phase Full-Wave Converter
Basic Configurations
Mid-Point Converters
Bridge Converters

8. Mid-Point Converters With R-Load Average dc voltage:
Avg.Load current is

9. With Inductive Load :

10. Some Conclusions from the given equation :
The highest value of this voltage will be when the
firing angle is zero i.e = 0°.
This voltage is zero when = 90°. Meaning
that the load voltage will contain equal positive
and negative areas, giving zero output voltage.
This voltage is negative maximum when = 180°.

11. For Firing angle 300

12. For Firing angle 900

13. For Firing Angle 1500

14. Effect of Free Wheeling Diode :
Average dc voltage :
Average dc current:

15. Bridge Converter(B-2 connection) :
R-Load :

16. With R-L Load:

17. Mode 1
Rectifying Mode :

18. Mode 2
Inverting Mode

19. Line Commutated Inverter :

20. Advantages of Single-Phase Bridge Converter over Mid-Point Converter
SCRs are subjected to a peak-inverse voltage of 2 Em in
mid-point converter and Em in fully controlled-bridge converter.
Hence, for the same voltage and current ratings of SCRs, power
handled by mid-point configuration is about half of that handled
by bridge configuration.
In mid-point configuration, each secondary should be able to
supply the load-power. As such, the transformer rating in
mid-point converter is double the load-rating. This, however,
is not the case in the single-phase bridge converter.

21. Half Controlled Bridge Rectifier :
R-Load

22. With R-L load :

25. Fully Controlled converter
Comparison of Half Controlled Converter with
Fully Controlled converter
Since half the thyristors are replaced by diodes, a half-controlled
converter costs less than a fully-controlled converter.
The periods of the negative-voltage “swing” at the d.c. terminals
obtained with fully-controlled bridge-circuit are replaced by
“freewheeling” periods of zero voltage in the half-controlled circuit.
The elimination of the negative swings of voltage at the d.c. terminals
is advantageous because it results in a reduction of the ripple voltage,
with correspondingly reduced filtering requirements.
In half-controlled bridge-circuit, the average d.c. terminal voltage
can be continuously controlled from maximum to virtually zero with
an increased control range of the firing angle .

26. Due to the freewheeling action with half-controlled bridge-circuit,
power factor is improved in half-controlled-converters.
The a.c. supply-current is more distorted due to its zero periods
with half-controlled circuit, compared to fully-controlled
bridge-circuit.

27. Three-Phase Controlled Converters :
Three-Pulse Converter
Six-Pulse Converter

28. Three-Phase Half wave Converter :
R-Load :
With resistive load, there are two modes of conduction. They are:
(1) Continuous conduction mode for .
(2) Discontinuous conduction mode for .

30. Three-Phase Fully Controlled Bridge Converter :
With R-Load

31. Continuous Conduction Mode :
Discontinuous Conduction Mode :

32. THANK YOU