Research On Sensorless Control Of Permanent Magnet Synchronous Motor In Full Speed Range

Permanent Magnet Synchronous Motor(PMSM)is currently an important basic component in the field of industrial drives.The advantages of PMSM include high reliability,small size,high efficiency and energy saving,and low torque of brushless comparing with DC motors.So it is widely used in transmission.At the moment,the sensorless control of PMSM can be divided into two main classes: One is based on the salient polarity of the motor,which is suitable for low speed and zero speed;the other is based on the model method,which is suitable for medium and high speed.Single algorithm is difficult to meet the requirements of motor running in full speed range.Therefore,a new algorithm combining sliding mode observer method and high frequency voltage injection method is proposed in this paper,which can accurately estimate the rotor position information from low speed to medium and high speed,so as to realize the full speed range sensorless control of PMSM.The main contents of the study are as follows:(1)Three-phase stationary coordinate system model in PMSM is stated specifically.After introducing the Clark and Park transformations,the mathematical model of PMSM in a two-phase stationary and rotating coordinate system is introduced.And discussed several commonly used vector control methods.(2)Based on the control strategy of i_d=0,the S-shaped function is used to replace the traditional switch control function aiming at the jitter problem existing in the traditional sliding mode observer.In view of the influence of permanent magnet flux changes on the rotor position,the phase-locked loop technology is used to estimate the rotor position,which improves the estimation performance of the traditional sliding mode observer method.The simulation results show that the improved sliding mode observer method can more accurately estimate the speed and rotor position information when the motor is running at medium and high speeds,and the system control performance is better.(3)Since the low-speed back-EMF is not easy to detect in the sliding mode observer method,the motor from start to low-speed operation by means of the rotating high-frequency voltage injection method.The band-pass filter and the high-pass filter are used to optimize the algorithm.The results show that the rotating high-frequency voltage injection method can obtain a good estimation effect of the rotor position and speed,and the system control performance is better.(4)In order to realize the smooth switch from low speed to medium and high speed,a fuzzy control algorithm is proposed.The shortcomings of the traditional low-speed to medium-speed and high-speed switching methods are analyzed,and the fuzzy control algorithm is used to realize the smooth switching of position and speed,which avoids the jump of position and speed during the transition.MATLAB / SIMULINK results show that PMSM sensorless control system can run stably from low speed to medium and high speed,and the effect is better.