Question

In single-phase modulation of PWM inverters, the pulse width is 120°. For an input voltage of 220 V dc, the rms value of output voltage is

(a) 185 V

(b) 254 V

(c) 127 V

(d) 179 V

I got this question by my college professor while I was bunking the class.

Enquiry is from PWM Inverters-4 in chapter Inverters of Power Electronics

Answer 1

The correct choice is (d) 179 V

For explanation I would say: Vo = (Vs) x (2d/π)^1/2

Where, d = 2π/3 and Vs = 220 V.