Question

A step down chopper has Vs = 220 V and is connected to RLE load. With R = 1 Ω, E = 24 V and L = 5 mH. The chopping period is 2000 μs and the on-period is 600 μs. Find the value of minimum steady state output current.

(a) 33 A

(b) 42 A

(c) 0 A

(d) 51 A

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This is a very interesting question from Type E Choppers-2 topic in division Choppers of Power Electronics

Answer 1

Right option is (d) 51 A

Explanation: I(min) = (Vs/R) x [ (1 – e^-m)/(1 – e^-n) ] – (E/R)

m = Ton / (L/R) = R.Ton/L = 0.12

n =  T/(L/R) = R.T/L

T = 2000μs

n = 0.4

I (min) = (220/1) x [ (1 – e^-0.12)/(1 – e^-0.4) ] – (24/1) = 51.46 A.