Analysis and realization of a pulsewidth modulator based on voltage space vectors

Abstract

A space vector concept for deriving the switching times for pulsewidth-modulated voltage source inverters is compared with the conventional sinusoidal concept. The switching times are deducted from assumptions for minimum current distortion, the resulting mean voltage values are shown, and the differences between these and the established sinusoidal PWM (pulse-width modulator) are elaborated. Based on an analytical calculation the current distortions and torque ripples are evaluated and compared with the values obtained with the conventional method. The space vector representation results in lower current harmonics and possibly a higher modulation index. A modulator based on an 8086 microprocessor has been implemented, and its performance is reported.