Carrier-based PWM techniques using stepped waveforms

A description is given of several stepped reference waveforms that can be used in carrier-based three-phase PWM at any given carrier frequency and fundamental voltage. The load current distortion factor is used to compare the performance of the various reference signals. Stepped reference waveforms are shown to be an effective way of minimizing the current distortion at all carrier frequencies and fundamental magnitudes, Three modulation techniques are identified: amplitude PWM; modified PWM and the alternative PWM. The reference signal that minimizes the current distortion is shown to be dependent on the fundamental magnitude and the carrier frequency