Analysis of the Discontinuous PWM Strategies Applied to the VSI

Fully digital AC drives with pulse width modulator inverters are becoming an industrial standard. For PWM inverters the most commonly used is the conventional sine PWM (SPWM). An attempt to improve this carrier based strategy is presented by means of the introduction of discontinuous techniques; such as the dead band PWM (DBPWM) and the modified SPWM (MSPWM). Their characteristics and qualities are evaluated by some performance criteria such as, modulation index concerning the inverter output voltage fundamental, the distortion factor of the load current, torque harmonics, and the influence of the switching frequency upon losses in the converter.