Question

The below given circuit has Vs = 230V and R = 20 Ω. Find the value of the average output voltage at the R load for a firing angle of 45°.

(a) 224 V

(b) -15.17 V

(c) 15.17 V

(d) –224 V

This question was posed to me by my college director while I was bunking the class.

My doubt is from AC Voltage Controllers-3 topic in division Voltage Controllers of Power Electronics

Answer 1

Correct choice is (b) -15.17 V

For explanation I would say: Vo = [(√2 x 230) x (cos45 – 1)]/2π = -15.17 V.

Negative value is due to the fact that the average value in the positive half cycle is less than that in the negative half cycle.