Question

A voltage commutated chopper feeds power to an electric car (battery-powered). The battery voltage is 60 V. Starting current is 60 A and the SCR turn-off time is 20 μs. Calculate the value of inductance (L) required for the commutating circuit.

(a) 400 μH

(b) 40 nH

(c) 40 μH

(d) 0.4 mH

The question was posed to me in examination.

The query is from Thyristor Chopper Circuits-2 topic in section Choppers of Power Electronics

Answer 1

The correct option is (c) 40 μH

The explanation is: L = (Vs/Io)^2 x C

C = (tc x Io)/Vs

C = ( 40 x 60 x 10^-6)/60 = 40 x 10^-6 F

L = (60/60)^2 x 40 x 10^-6 = 40 uH.