Sensorless control of brushless DC motors using virtual back EMF mapping projection

This paper presents a new approach for sensorless control of brushless dc motors (BLDCM). A linear back emf line is constructed reflecting the rotor displacement angles, from which the commutation instances corresponding to 30° degrees are computed. The approach increases the signal to noise ratio and improves the performance as compared with zero crossing detection point (ZCP) method. Simulation results are presented for a DC brushless drive at various load conditions. It is shown that the virtual effect sensors (VHE) signals follow the same interval as physical Hall effect (PHE) signals