A novel sensorless method of brushless DC motor based on 180-degree commutation

In this paper, a novel sensorless-drive method of 180-degree commutation is proposed. Inverter gate signals are generated by using the zero-crossing points of estimated back-emf signals, also by comparing the polarities of the estimated back-emf signals. The estimated trapezoidal back-emf signals are obtained by sensoring the three phase-current of motor and the inverter output voltage. Rather than the conventional estimation methods, the proposed method cancels the complicated calculation-steps, which can burden DSP in practical experiments. The simulation under Matlab/Simulink environment shows that the proposed method works properly to make the sensorless drive easy, without estimation of speed and position information.