Question

Find the expression for the ripple factor in terms of duty cycle α for a type A step down chopper

(a) √(1-α/α)

(b) α^2/2

(c) √α/2

(d) √(1-α)

This question was addressed to me during an interview.

The query is from Type E Choppers-2 topic in chapter Choppers of Power Electronics

Answer 1

Correct choice is (a) √(1-α/α)

The best explanation: RF = Vr/Vo

Vr = √α x Vs = √(αVs^2 – α^2Vs^2) = Vs √(α- α^2)

RF = Vs.√(α- α^2)/Vs.α = √(1-α/α).