Single Phase Half Wave Controlled Rectifier with 'RL' load:

1) Normally motors are inductive loads

a. L= armature of field coil inductance

b. R= Resistance of coil.

2) In positive half cycle, SCR starts conduction at firing angle ' '.

3) Drop across SCR is small & neglected so output voltage is equal to supply voltage.

4) Due to 'RL' load, current through SCR increases slowly.

5) At 'ϖ', supply voltage is at zero where load current is at its max value.a

6) In positive half cycle, inductor stores energy & that generates the voltage of L.

7) In negative half cycle, the voltage developed across inductor, forward biases SCR & maintains its conduction.

8) Basically with the property of inductance it opposes change in current.

9) Output current & supply current flows in same loop, so all the time io=is.

10) After ϖ the energy of inductor is given to mains & there is flow of 'io'. The energy reduces as if gets consumed by circuit so current also reduces.

11) At 'β' energy stored in inductance is finished, hence 'io' becomes zero & 'T1' turns off.

12) 'io' becomes zero from 'β' to '2ϖ+α' hence it is discontinuous conduction.


Performance Parameter of Single Phase Half Wave Controlled Rectifier (RL):

Sr No



Average DC output voltage (VLdc)-


Normalized output voltage (Vn)


RMS output voltage (VLrms)-


Form Factor (FF)-


Ripple Factor (RF)-


DC output Power (PDC)-


AC Input Power (PAC)-


Reflection Efficiency (Æž)-