Sensorless Control And Error Compensation Of High-speed Permanent Magnet BLDCM

The high-speed permanent magnet BLDCM Based on sensorless control has the advantages of simple structure,small size and strong adaptability,and has a broad application prospect in high-speed occasions such as aerospace.But at high speed,the problem of commutation error in traditional sensorless control method is more obvious,which directly affects the operation efficiency and reliability of high-speed permanent magnet BLDCM.In order to realize the sensorless control of high-speed permanent magnet BLDCM and solve the problem of commutation error,this paper proposes a method of commutation error compensation under the sensorless control by analyzing the linear back EMF characteristics before and after the commutation point.Firstly,the back EMF method based on the virtual neutral point voltage is used to get the zero crossing point of the motor suspended opposite EMF,and the estimated commutation point of the motor is obtained.Then,the terminal voltage of the motor is obtained by synchronous sampling,and the objective function of the motor is constructed by selecting the appropriate line voltage in different commutation intervals,so that the objective function is only related to the terminal voltage of the motor.Finally,the two integral regions are determined by the estimated commutation point,and the objective functions are integrated separately.According to the trend of the integral difference,the corresponding relationship between them and the commutation error angle is obtained,so as to determine the error of the motor estimated commutation point and compensate it,so as to realize the sensorless control of the motor.Because the calculation of the objective function is only related to the terminal voltage of the motor and does not depend on the parameters of the motor itself and the ideality of the back EMF,the method has strong robustness.At the same time,this method is not affected by the motor speed,so it can still accurately compensate the motor commutation point under the condition of variable speed.Based on the high-speed permanent magnet BLDCM,an experimental system platform is built in this paper.Based on the virtual neutral point voltage of the motor,the estimated commutation point of the motor is obtained.Under the constant speed and variable speed conditions,the error compensation of the estimated commutation point is carried out,and the accurate commutation of the motor is realized.The experimental results prove the correctness and effectiveness of this method.