A critical survey of techniques used in 3-phase carrier-based PWM to lower the current distortion

The theoretical developments are described which form the basis for specifying the most appropriate reference signal that should be used in the carrier-based pulse width modulation (PWM) technique at any given carrier frequency and fundamental voltage. The load current distortion factor is used to compare the performances of various reference signals. The performances of the traditional carrier-based PWM techniques, using sinusoidal reference signals, are established to provide a means for comparison. A modified square-wave reference is shown to provide a low current distortion at very low carrier frequencies. A modified PWM technique can be adopted to lower the current distortion at very low carrier frequencies and also at large fundamental magnitudes. The reference signal that minimizes the current distortion is shown to be dependent upon the fundamental magnitude and the carrier frequency.<>