Unit 3 phase controlled converters

1. Power Electronics
UNIT-3
Phase Control Rectifier
PREPARED BY :
MERAJ AKHTAR
ELECTRICAL DEPARTMENT
JIT BARABANKI

2. Principle of Phase Control
Single phase Half wave Control with R
load

3. Waveforms

4. Performance Parameters
• Average O/P Voltage
The maximum value of output voltage occurs at α = 0° ,
Vom = (Vm/2ᴨ).2 = Vm/ᴨ

5. Continued….
• Average Load Current ,
• RMS value of load voltage (For electric heating and
incandescent lamps)

6. Continued….
• Power delivered to Resistive Load = (RMS load voltage x
RMS load current)
• Input Volt Amperes = (rms source voltage x total rms line
current) = Vs . Ior
• Input power factor = Power delivered to load/Input VA =
(Vor.Ior)/(Vs.Ior) = (Vor/Vs)
• Input displacement factor (DF) or fundamental power factor =
cos (angle between supply voltage and current)
• Input current distortion factor (CDF) – Ratio of rms value of
fundamental component Is1 of the input current to rms value
of input = Is1/Is

7. Continued….
• Rectification ratio : ratio of DC output power to AC
output power
Also known as rectification efficiency or figure of merit
. In case forward resistance Rd then

8. Continued….
• Form Factor (FF) – Ratio of rms value Vor of output voltage to
the dc value of Vo
FF is a measure of shape of output voltage.
Close to unity, better dc output voltage waveform

9. Continued….
• Voltage Ripple Factor (VRF) : Ratio of ripple voltage
to the average output voltage.
Effective or, Ripple value of the ac component of output
voltage is given by

10. Continued….
• Transformer Utilization Factor (TUF) :
Rms secondary voltage and current or, transformer VA
rating

11. Single phase Half wave Control with
R-L load

12. Continued….

13. Continued….

14. Single phase Half wave Control with
R-L load & Free Wheeling Diode

15. Continued….

16. Continued….
• Freewheeling diode, by pass or commutating
diode
• Two modes are :
Conduction mode
Free wheeling mode

17. Continued….
• Input pf is improved (power delivered to load in both
modes / Input KVA)
• Load current waveform is improved
• From above, load performance is better
• As energy stored in L transferred to R during the
freewheeling period, overall converter efficiency
increases.
• Supply current is unidirectional in both cases (dc
pulses) introduces dc component to supply line. This
is undesirable as as it leads to saturation of supply
transformer and harmonics etc

18. Continued….

19. Single phase Half wave Control with
R-L-E load

20. Continued….

21. Continued….
• Firing angle lies :

22. Full wave Controlled Converters
• SCR controlled converters (or rectifiers)
Classification:
According to No of supply phases to input
According to No of load current pulses during one cycle
of source voltage

23. Continued….

24. Continued….

25. Single Phase Full wave Converters
• Single Phase Full wave mid point converter (M-2
connection)
• Single Phase Full wave Bridge converter (B-2
connection)

26. Single Phase Full wave mid point converter
(M-2 connection)

27. Waveforms

28. Single Phase Full wave Bridge Converter
(B-2 connection)

29. Waveforms

30. THANKING
YOU