Carrier-based PWM-VSI overmodulation strategies: Analysis, comparison, and design

In this paper, the overmodulation region voltage-gain characteristics and waveform quality of carrier-based pulsewidth-modulated (PWM) methods are investigated. Through detailed analytical stud, voltage-gain characteristics are extracted independent of carrier frequency, The influence of blanking time and minimum pulsewidth (MPW) control on the inverter gain characteristics are studied and shown to be significant. A comparative evaluation of the modulator characteristics reveals the advantageous high-modulation-range characteristics of discontinuous PWM methods and, in particular, the superior overmodulation performance of a discontinuous PWM method, The modulation methods under consideration are tested on a PWM voltage-source inverter (VSI) fed induction motor drive in the laboratory, and the theoretical results are verified by experiments. Also, a gain linearization technique is presented and experimentally verified, The results of this study are useful in design, performance prediction, and development of high-performance overmodulation strategies for PWM-VSI drives.