Sensor reduction in a PFC-based isolated BL-SEPIC fed BLDC motor drive

Abstract

This work presents an improved power quality-based isolated bridgeless single-ended primary inductance converter (BL-SEPIC) fed brushless DC (BLDC) motor drive using a single voltage sensor. The voltage of DC bus of voltage source inverter (VSI) feeding BLDC motor is varied for controlling the speed of BLDC motor and operating the VSI in low frequency switching for electronically commutating the BLDC motor for minimal switching losses. A front-end isolated bridgeless configuration of SEPIC is used which offers reduced conduction losses. The BL-SEPIC is designed to operate in discontinuous conduction mode (DCM), thus utilizing a simple control of voltage follower. The sensorless control of BLDC motor is also used for elimination of rotor position sensors. The performance of proposed drive is evaluated over a wide range of speed control with unity power factor (PF) at AC mains. The obtained power quality indices are under the recommended limits of IEC 61000-3-2.