Research On Sensorless Control Of High-speed Brushless DC Motor

Traditional high-speed brushless DC motors need to install position sensors to obtain rotor position and speed information.The position sensor will cause the cost of the motor control system is increased,reducing the reliability,these disadvantages limit the application of high-speed brushless DC motor.In response to these problems,this paper studies the sensorless control of high-speed brushless DC motors.As the high-speed sensorless brushless DC motor cannot obtain accurate back EMF when it is at rest and at low speed,this article proposes "Three-stage" startup algorithm suitable for high-speed sensorless brushless DC motors based on several commonly used sensorless starting algorithms and the characteristics of high-speed brushless DC motors.When the motor speed is higher than 20000 Rpm,the commutation time of each step of the motor will reach the level of microseconds.At this time,there will be commutation errors unique to high-speed brushless DC motors;By analyzing the phase relationship between the back EMF and the phase current during the leading and lagging commutation,it is concluded that the phase difference between the two is the commutation error.Aiming at the commutation error of the motor,this paper proposes to use the phase difference between the terminal voltage and the phase current as the error compensation signal,and perform error compensation on the commutation signal based on the traditional back-EMF algorithm.Simulation results show that: the control algorithm improved to run more stable when the motor speed reaches 100000 Rpm,and good anti-jamming capability.The hardware system of the high-speed brushless DC motor Sensorless control system is designed based on the GD32E231 chip;The startup algorithm,the commutation algorithm and the improved back EMF algorithm of the high-speed brushless DC motor sensorless control system are written based on the C program.Finally,the entire software design was completed using the KEIL5 software platform.The experimental results show that the control system based on the GD32E231 chip can realize the control of the high-speed sensorless brushless DC motor.Due to the limitation of the experimental motor’s own back EMF,the motor rotates safely and stably within 8000 Rpm to40900Rpm.