Question

In case of a single-pulse width modulation with the pulse width = 2d, to eliminate the 3rd harmonic from the output voltage waveform, the value of the pulse width (2d) must be

(a) 0°

(b) 60°

(c) 120°

(d) 180°

This question was posed to me in homework.

Question is taken from PWM Inverters-1 in chapter Inverters of Power Electronics

Answer 1

Right answer is (c) 120°

Explanation: To eliminate the nth harmonic, nd = π.

Therefore, d = π/n = π/3 = 60°

Hence, 2d = 120°.