Staircase PWM: an uncomplicated and efficient modulation technique for AC motor drives

摘要

An optimized staircase PWM (pulse-width modulation) technique is presented. The fundamental voltage component (U/sub (1)/) is proportional to the staircase amplitude (M). Values of U/sub (1)/ higher than 90% of the corresponding value for the nonmodulated waveform are attained for M=1. The staircase is not a sampled representation of a sine wave and the number of steps and the frequency ratio are selected for a desired output voltage quality. A criterion for evaluating the quality of the output voltage (the weighted relative harmonic content) is presented. The control logic is uncomplicated and implemented by inexpensive complementary metal-oxide semiconductor logic with high noise immunity and reliability. The results have been verified by tests.