A Single-Stage PFC Half-Bridge Converter Controlled Adjustable Speed PMBLDCM Drive
The PMBLDCM is used to drive a compressor load of an air conditioner through a three-phase VSI fed from a controlled DC link voltage. A buck half-bridge DC-DC converter is used as a single-stage Power Factor Correction (PFC) converter for feeding a Voltage Source Inverter (VSI) based Permanent Magnet Brushless DC Motor (PMBLDCM) drive. The front end of this PFC converter is a Diode Bridge Rectifier (DBR) fed from single-phase AC mains. The speed of the compressor is controlled to achieve energy conservation using a concept of the voltage control at DC link proportional to the desired speed of the PMBLDCM. Therefore the VSI is operated only as an electronic commutator of the PMBLDCM. The stator current of the PMBLDCM during step change of reference speed is controlled by a rate limiter for the reference voltage at DC link. The proposed PMBLDCM drive with voltage control based PFC converter is designed, modeled and its performance is simulated in Mat lab- Simulink environment for an air conditioner compressor driven through a 1.5 kW, 1500 rpm PMBLDC motor. The evaluation results of the proposed speed control scheme are presented to demonstrate an improved efficiency of the proposed drive system with PFC feature in wide range of the speed and an input AC voltage.