Optimum non-deterministic pulse-width modulation for three-phase inverters

Recent advances in power semiconductor technology associated with the development of fast switching devices such as MOSFETs, IGBTs, etc., favour the use of random modulation techniques in power electronic converters. The major advantage for using such a strategy is nonrepetitive output spectral characteristics which further result in reduction of acoustic noise, minimization of torque pulsations on the motor side, etc. In this paper, an optimum nondeterministic pulse-width modulation, suitable for three-phase voltage controlled inverters, is proposed. The most notable features of the random modulator under consideration are the significant reduction in converter average switching frequency and its unity gain which make it even more attractive for medium power applications. Simulation results are presented and theoretical considerations are also verified on an experimental unit