In this paper, a feed forward controller is used to compensate DC bus capacitor unbalance voltages at neutral point of two divide capacitors of half bridge boost converter & control DC link voltage ripples of BLDCM drive system based half bridge boost AC-DC converter & four switch inverter. Here input voltage is doubled as voltage doublers and is fed to four switch inverter to operate three phase BLDC motor. A four switch inverter uses a new switching pattern operating in six different modes instead of six switch inverter for the purpose of low cost effective applications. Simulation results indicate that a feed forward controller is used to compensate unbalance capacitor voltages at neutral point and control DC link voltage ripples, if three phase BLDC motor is coupled to two legs of four switch inverter while one phase of motor is connected to the neutral point of two divide DC bus capacitors of half bridge boost AC-DC converter. Improved power factor is achieved using half bridge boost AC-DC converter instead of diode rectifier.

Keywords: Brushless DC (BLDC) motor, Half Bridge Boost AC-DC Converter, Four Switch Inverter, Feed Forward controller