Position Sensorless Control for PMBLDC Motor Drive Using Digital Signal Processor

This paper presents a complete position sensorless control scheme for permanent magnet brushless DC motors (PMBLDCMs) using back-EMF sensing method. The controller is designed in such a way that it provides smooth shifting from open-loop speed-up mode to back-EMF sensing mode at any speed, especially at very low speeds, i.e., less than 2% of the rated speed. The proposed scheme is a simple and cost effective implementation of back-EMF sensing method, which does not require any filtering or phase shift to generate commutation pulses. The proposed controller is designed and modeled for a PMBLDCM rated at 4600 rpm, 310 V and 2.2 N.m torque and its performance is simulated in MATLAB/SIMULINK environment. The obtained simulation results are validated on a prototype developed in the lab using a digital signal processor (DSP) namely TI 2812 DSP in a wide range of speeds in position sensorless mode.