An integral space-vector PWM technique for DSP-controlled voltage-source inverters

Abstract

A novel pulsewidth modulation (PWM) technique for voltage-source inverters, based on the idea of space vectors of switching integrals is presented. In contrast to most existing PWM methods, no explicit timing is required, smooth transition from the PWM mode to the square-wave mode is ensured, and minimum allowable widths of pulses and notches are guaranteed. The control algorithm is conceptually simple and easily implementable in a digital signal processor. Four parameters of the modulation strategy are adjustable, allowing tuning of the modulator to requirements imposed by the application. Voltage spectra have a low harmonic content, most of the power being dispersed as the continuous power density. A prototype modulator is described and illustrated by the results of laboratory experiments.