Microprocessor controlled inverter for UPS applications

A microprocessor controlled PWM generator for UPS applications is presented. The method adopted for generating the PWM pulses is based on a combination of on-line calculation and look-up-table based data. A modular programming facility utilised to provide easy and efficient handling of the large quantity of look-up-table data. The simple technique used to eliminate the effects of interrupt delays, worked very well in practice and can be employed in three phase systems. The scheme used to generate the PWM pulses utilised only two mathematical operations. This allows the microprocessor adequate time to perform other functions satisfactorily, such as regulating the output voltage and implementing the phase-synchronisation technique, despite the relatively high carrier frequency