Describe the operation of single phase half wave controlled rectifier with RL load.

Ans:

Circuit diagram:

Working:

• During positive half cycle of input voltage, thyristor T is forward biased but it does not conduct until gate signal is applied to it. 

•  When a gate signal is given to thyristor T at wt = α, it gets turned ON and begins to conduct. 

•  When thyristor is ON the input voltage is applied to the load, but due to the inductor present in the load, current through load builds up slowly. 

•  During negative half cycle of input voltage, thyristor T is reverse biased but current through thyristor is not zero due to inductor. 

• The current through inductor slowly decays to zero 

• So here thyristor will conduct for some time during the negative half cycle and turns OFF at wt = β. 

•  Now the load receives voltage during positive half cycle and for a small duration in negative half cycle. 

•  The average value of voltage can be varied by varying firing angle α.