Question

The SCR T1 is fired at an angle of α, and the supply Vs = Vm sinωt. Find the average value of the output voltage.

(a) (Vm/2π) (cosα + )

(b) (Vm/2π) (cosα)

(c) (Vm/2π) (cosα – 1)

(d) Vm

I got this question by my school principal while I was bunking the class.

Question is from AC Voltage Controllers-2 topic in portion Voltage Controllers of Power Electronics

Answer 1

Correct choice is (c) (Vm/2π) (cosα – 1)

For explanation I would say: Vo = (1/2π) ∫Vm sinωt d(ωt). Where the integration would be run from α to 2π as the conduction takes place from α to 2π.

Vo =  (Vm/2π) (cosα – 1).