A DC source supplies an inverter with bipolar PWM control. The effective value of the output voltage on the fundamental frequency of 50 Hz is 220 V. The load is a serial R-L connection with a resistance R = 10 Ω and an inductance L = 50 mH.
(a) Specify the amplitude modulation ratio if the DC voltage is 444 V.
(b) If the frequency modulation ratio is 21, determine the THD of the load current.