Experimental analysis of symmetrical & asymmetrical PWM based single phase AC chopper for power quality improvement using FPGA real time controller

A 1-phase AC chopper circuit is rigged up and analyzed with single phase induction motor for input power factor, harmonic profile and efficiency of the converter using FPGA real time controller. The various PWM techniques such as symmetrical ramp-DC PWM (SRDPWM), asymmetrical ramp-triangular PWM (ARTPWM), asymmetrical sinusoidal PWM type-1 [ASPWM1] and asymmetrical sinusoidal PWM type-2 [ASPWM2] techniques are generated using FPGA real time controller in order to analyze these electrical parameters. It is observed from experimental results that the SRDPWM technique gives lesser total harmonic distortion [THD] of output voltage and input current than other techniques. It is also observed that the ASPWM1 switching strategy gives high input power factor, more output voltage and high efficiency and moderate improvement of harmonic profile for the entire range of modulation index MI compared to other PWM techniques. Hence ASPWM1 technique is preferred for AC chopper for better input power factor, output voltage, harmonic profile and efficiency of the converter than other techniques that renders easy filteration at lower cost.