Research On Position Sensorless Control Strategy Of High Speed PMSM

The Permanent Magnet Synchronous Motor is widely used in the field of AC transmission due to its advantages of simple structure,low energy consumption,and fast dynamic response.However,as a high-order,nonlinear,strongly coupled,and multi-parameter physical system,traditional control methods are difficult to meet the requirements of high-performance control.To achieve high-performance vector control of the system,accurate rotor position information is necessary.The traditional method is to use mechanical position sensors,but they have high manufacturing and maintenance costs and are difficult to apply in some extreme environments.Therefore,research on PMSM sensorless technology has been widely conducted.This paper focuses on a surface-mounted permanent magnet synchronous motor and designs a low-cost,easy-to-implement,and full-range sensorless composite control scheme for its applications in compressors,fans,and pumps.In the zero and low-speed range of motor operation,the high-frequency square wave voltage injection method is first used to determine the initial position of the rotor.Then,the I/F control strategy is selected for start-up,and the amplitude of the start-up current is adjusted in real-time based on changes in speed,reducing energy loss and improving the start-up efficiency of the motor.During the transition from the zero and low-speed range to the medium and high-speed range of motor operation,a fixed slope reduction method is used to achieve a smooth transition between zero and low-speed start-up and medium and high-speed operation,avoiding speed and torque oscillations caused by improper switching methods.In the medium and high-speed range of motor operation,an improved sliding mode observer is studied,which simplifies the system structure and effectively suppresses high-frequency jitter and phase delay phenomena by adapting the sliding mode gain according to speed,using threshold functions and back electromotive force observers.In addition,to avoid the influence of speed changes on system bandwidth and response speed in traditional phase-locked loops,a normalized phase-locked loop is designed to improve observation accuracy and robustness of the system.Based on theoretical analysis,a Matlab/Simulink simulation model is built for modeling and analysis,and experiments are conducted on a control experimental platform with TMS320F28335 microcontroller as the main control chip.Simulation and experimental results show that the designed control scheme can stably and reliably start the system,smoothly transition to the dual-loop vector control mode at medium and high speeds,and has good dynamic and static performance under the dual-loop vector control mode.These experimental results verify the rationality of the design scheme and have a wide range of application prospects.