A 3-phase PWM strategy using a stepped reference waveform (for drive control)

A carrier-based, three-phase pulse-width modulation (PWM) technique for the control of motor drives that uses a stepped waveform as the reference signal is presented. The theoretical derivation of the stepped reference signal from a square-wave reference is described. Comparisons with existing sinewave PWM techniques, adopting third-harmonic boosting and regular sampling techniques, show that the square-wave PWM has a superior performance at low carrier frequencies. The adopted stepped reference waveform is shown to improve upon the square-wave strategy at high carrier frequencies. The practical realization of the PWM technique is described using performance criteria such as minimum pulse-widths, peak carrier frequencies, and the current harmonic distortion.<>