基于无刷直流电机的无位置传感器控制实现，利用反电动势检测电路获取电机转子的过零点，然后延时30°进行换相(Based on Sensorless Control of brushless DC motor, the zero-crossing point of motor rotor is obtained by using back-EMF detection circuit, and then commutation is carried out with a delay of 30 deg