A new method for sensorless control of brushless DC motor

In the process of sensorless control of brushless DC motor, the scope of the motor is limited by the traditional method for the detecting the rotor position of the EMF. In order to solve the problem, a new method of detecting the rotor position with zero crossing detection is proposed. Using H_PWM-L_ON pulse width modulation method, according to the two kinds situations of the high speed of the motor and low speed, different sampling method are chosen which accurate detection of anti electric potential over zero. At the same time, one end staying away from the fault of a voltage divider connected to the comparator is connected to the I/O of STM32, the connection method of the voltage resistance of the motor at different speeds is different by controlling the I/O port. The control improves the effect of the motor at different speeds over the zero crossing detection signal, so as to expand the scope of the motor. Through the experimental verification, the method can make the motor work in a wider range, and it has a certain feasibility and validity.