Direct synchronized PWM techniques with linear control functions for adjustable speed drives

Novel techniques of direct synchronous pulsewidth modulation (PWM) for three-phase voltage source inverters with basic continuous and discontinuous schemes of PWM are considered in this paper. They are based on a new strategy of feedforward PWM with quasi-linear control dependencies, providing synchronization of the voltage waveforms and linear voltage control during the whole range including the zone of overmodulation. Algebraic and trigonometric versions of the method proposed, based on vector approach for determination of the pulse patterns, are analyzed and compared. Both one-stage and two-stage variants of synchronous PWM are considered. The determination of the basic parameters of the output voltage of the inverter with low switching frequency are presented. Simulations give the behavior of the proposed techniques.