Analysis and comparison of algebraic and trigonometric methods of synchronous PWM for inverter drives

This paper presents a novel method of direct synchronous pulsewidth modulation (PWM) for three-phase voltage source inverters, feeding induction motors with different control regimes. It is based on the universal algorithm with either simplified algebraic or accurate trigonometric control functions, with vector approach for determination of the pulse patterns. Different control modes of the drive systems with synchronous PWM, including standard scalar V/F control, and also control regimes with nonlinear control dependencies between the fundamental voltage and frequency, have been analysed in the paper. Simulations give the behaviour of the PWM techniques proposed. Both continuous and discontinuous schemes of synchronous PWM, applied for the corresponding control regime, have been analysed and compared.