Power quality improvement of a position sensorless controlled PMBLDCM drive using boost converter

This paper proposes a boost converter for power quality improvement at input AC mains of a permanent magnet brushless DC motor (PMBLDCM) operated under position sensorless control. Presently hall sensors are used as position sensors in PMBLDCM and its signals are utilized for starting and control of PMBLDCM under various operating conditions. For the position sensorless control, back-EMF signal of PMBLDCM is used to detect its rotor position. A pulsed starting method is proposed for position sensorless starting which uses the PMBLDCM as a synchronous motor at standstill. The PMBLDCM is driven to a threshold speed where the back-EMF is detectable and the control of motor is shifted to position sensorless running mode. The PMBLDCM drive is generally fed by a single phase AC mains followed by a diode bridge rectifier (DBR) and a dc link capacitor through a three phase inverter. In the proposed work, a boost DC-DC converter is used for power factor correction (PFC) at input AC mains and to control the DC link voltage using current multiplier approach. The proposed method of power quality improvement of a position sensorless controlled PMBLDCM drive using boost converter is designed, modelled in Matlab-Simulink environment and its performance is evaluated under speed, torque and input AC voltage variations. The obtained results show improved power quality at AC mains along with smooth starting from standstill and during speed and torque control of the PMBLDCM drive operated in position sensorless mode.