DSP based Three Level PWM for Two Phase VSI

Abstract

Three level PWM schemes offer more output voltage and less switching losses as compared to the two-level PWM strategy. For inductive loads, due to lack of zero voltage freewheeling path in a three level PWM, the load current waveform distorts and contains unwanted low order harmonics. Analysis of inverter performance with three-level PWM driving inductive load has not been investigated so far. In this paper the performance of a two-phase inverter driving a two-phase induction motor is investigated with three-level PWM technique. The three-level PWM scheme is modeled using regular sampling strategy. The scheme is implemented with a TMS320C50 digital signal processor and tested on a prototype MOSFET inverter with a 0.5HP two-phase motor load. The experimental performance is found in good agreement with the theoretical results, validating the theoretical model of the three-level PWM for two-phase VSI.