NEW PWM SWITCHING STRATEGY FOR MICROPROCESSOR CONTROLLED INVERTER DRIVES

A new high-voltage suboptimal (HVSO) pulse-width modulation (PWM) switching strategy is presented which can be used at high fundamental PWM voltages to achieve a smooth, transient-free, low harmonic distortion, transition form the PWM to quasisquare-wave mode. The design philosophy underlying the development of the new HVSO strategy is aimed at reproducing the special features and desirable characteristics of the optimised PWM strategy, using a simple and efficient microprocessor implementation. The theoretical development of the new HVSO strategy is presented. Experimental results, from a microprocessor controlled PWM inverter drive, are provided which confirm this theoretical development. It is shown that the new HVSO strategy is superior to existing PWM strategies, and can be implemented simply and efficiently on a microprocessor controlled with only minor modifications to the existing PWM microprocessor implementations.