A New BEMF Technique for the Sensorless Control of PMBLDC Motor Drive

PM brushless DC motor provides an upper edge over other motors like induction & synchronous motors in terms of its high torque to weight ratio and simple structure and thus taken into account for a wide range of applications. For the control and operation of PMBLDCM, both sensorbased and sensorless techniques are used. Sensor-based techniques involve hall sensors, encoders, etc. to detect the rotor's position, which generally results in increased cost and reduced reliability due to the temperature constraints of these sensors. In this paper, a new BEMF technique is proposed for sensorless control of the PMBLDC motor. As we know that the BEMF waveform of each phase is equally distributed in positive and negative halves and in this technique, the positive polarity of the BEMF is allocated to generate switching pulses for the commutation of upper hand switches (Sl, S3, S5) of the inverter and negative polarity BEMF to generate switching pulses for lower hand switches (S2, S4, S6). By using this technique, 120
⁰
mode operation of the PMBLDC motor is achieved. The proposed scheme is simulated in MATLABSimulink software environment and the obtained results are presented to prove the effectiveness of the proposed technique.