Research On Medium Speed Position Sensorless Control Of Permanent Magnet Synchronous Motor For Vehicle

Permanent magnet synchronous motor drive system is widely used in various high-power AC drives due to its advantages of good inherent performance,fast dynamic response and high efficiency.At present,the precise control of permanent magnet synchronous motor systems mainly relies on photoelectric encoders and resolvers.However,the installation of these sensors will increase the cost and size of the motor,and reduce the reliability.Aiming at the problem that dynamic decoupling cannot be achieved by current feedforward decoupling in permanent magnet synchronous motor,this paper proposes complex vector decoupling to achieve complete decoupling.At the same time,the sliding mode observer has chattering and phase delay problems,and an improved A sliding mode observer control strategy is optimized to drive the motor.The main research contents of the paper are as follows:Firstly,the development status of permanent magnet synchronous motors at home and abroad is investigated.By analyzing the current research status of control strategies,it is clear that the innovations of the paper focus on improving the current feedforward dynamic decoupling of permanent magnet synchronous motors and solving the chattering and phase delay of the sliding mode observer.The problem.Secondly,the principle of feedforward decoupling of permanent magnet synchronous motor is studied.By analyzing the influence of inductance,speed and resistance on motor control performance,it is found that current feedforward decoupling control can only complete the d-axis and q-axis of permanent magnet synchronous motor.Static decoupling,however,the cross-coupling phenomenon still exists in the dynamic regulation,and the coupling phenomenon becomes more pronounced as the rotational speed increases.Therefore,the current complex vector decoupling strategy is designed.By analyzing the influence of the inductance,speed and resistance on the motor control performance under the complex vector decoupling control of the motor,it is verified that the complex vector decoupling can make The zero point negates the dominant pole,and as the motor speed increases,the stability of the system does not decrease,perfectly eliminating the coupling phenomenon.Thirdly,in view of the chattering and phase delay problems of the sliding mode observer,an improved sliding mode observer based on complex coefficient filter is designed,and a switching function based on a new piecewise function is designed to reduce the chattering of the motor control system.Since the complex coefficient filter has no phase delay at the center frequency and no amplitude attenuation occurs,the low-pass filter in the motor control system is replaced with a complex coefficient filter,thereby improving the control performance of the motor system;design The signal processing module based on the normalized phase-locked loop improves the observation accuracy;through MATLAB simulation verification,the improved sliding mode observer runs more stably and has better control performance.Finally,a permanent magnet synchronous motor drive experimental platform is built to verify the performance of the motor control strategy designed in this paper under medium speed conditions.It can be seen from the results that the motor control strategy designed in this paper has significant advantages in reducing chattering,improving current steady-state performance,improving the accuracy of motor speed observation,and facing the sudden change of speed.