- AVINASH MISHRA

SINGLE PHASE SEMICONVERTER

(R-L LOAD)

INTRODUCTIONConverter

Rectifier circuit

Uncontrolled Rectifier circuit

Controlled Rectifier circuit

CLASSIFICATION OF RECTIFIERS

SEMI CONVERTERIt 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.

Symmetrical configuration of semiconverter

Asymmetrical configuration of semiconverter

OPERATION WITH R-L LOAD

MODE 1

Here when SCR 1 is turned on.

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.

MODE 2

Here at freewheeling occurs.

OBSERVATION OF MODE 2 Here 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. Hence diode Dfw starts conducting due

to freewheeling.

MODE 3 Here at SCR 2 & D 2

is ON.

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.

MODE 4

Here at freewheeling occurs.

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.

SUMMARY