Voltage harmonic adjustment of Cuk and SEPIC converters

Abstract

Voltage harmonics are present on electrical power lines today. These harmonics are voltage fluctuations which can be the result of dc to dc converters due to their high frequency switching called Pulse Width Modulation (PWM). PWM switch ON and OFF very quickly to control their output voltage. If harmonics are high enough, it can cause other equipment connected to that same power line to fail prematurely, due to the equipment operating outside its designed voltage margin. This thesis shows that voltage harmonics can be adjusted by randomizing the PWM signal which is supplied to two dc to dc converters. The randomization technique applied is Random Pulse Width Modulation (RPWM), Random Phase Position Modulation (RPPM) and a combination of both RPWM and RPPM. These randomization techniques are applied to Single Ended-Primary Inductor Converter (SEPIC) and Cuk converters. The results show that some randomization techniques can adjust the voltage harmonics if the applied PWM has enough time margin to randomize within each pulse. RPPM technique adjusted the voltage harmonics the most.