1. SINGLE PHASE
SEMICONVERTER
(R-L LOAD)
- AVINASH MISHRA

2. INTRODUCTION
 Converter

Rectifier circuit
Uncontrolled Rectifier circuit
Controlled Rectifier circuit

3. CLASSIFICATION OF RECTIFIERS

4. SEMI CONVERTER
 It
is a single quadrant converter.
 It has only one polarity of output
voltage and current.
 Here two SCRs and two diodes are
connected in bridge configuration.
 They can be arranged in two confg.
namely symmetrically & asymmetrical.

5. Symmetrical configuration of
semiconverter

6. Asymmetrical configuration of
semiconverter

7. OPERATION WITH R-L LOAD

8. MODE 1
 Here
when
turned on.
SCR 1 is

9. OBSERVATION OF MODE 1
 Diode
d1 is forward biased,
 Conduction will take place through
SCR1 & D1,
 Load voltage is Vo=Vm sin ωt
 Here inductive load will store the
energy in this mode of operation.
 Flow of power is from source to
load.

10. MODE 2
 Here
at
occurs.
freewheeling

11. OBSERVATION OF MODE 2
AC vltg goes to zero & after ∏ it
becomes negative.
 Hence SCR 1 and diode D1 will turn
off.
 Since load is inductive it will try to
oppose the change in crt. Flowing
through it.
 Self induced vltg is induced.
 This load vltg is negative.
 Here

12. MODE 3
 Here
at
SCR 2 & D 2 is ON.

13. OBSERVATION OF MODE 3
Load
vltg is positive =
instantaneous vltg.
Supply crt is negative.
Hence load vltg & crt both
being negative it will store
energy.

14. MODE 4
 Here
at
occurs.
freewheeling

15. OBSERVATION OF MODE 4
 Here
AC supply vltg reverses its
polarity & becomes positive.
 Here also hence freewheeling
starts through Dfw.
 Load vltg is zero.
 Supply crt is zero.

16. SUMMARY