Sensorless Control Of Permanent Magnet Synchronous Motors In The Full Speed Range

Due to its excellent performance,permanent magnet synchronous motors are widely used in various electric drive fields.When controlling the motor,the speed and position signals are indispensable information,and they are usually obtained by installing mechanical position sensor.However,the reliability of mechanical position sensors is easily affected by environmental factors and is usually expensive,which limits the application of permanent magnet synchronous motors to a certain extent.The proposal of sensorless control technology overcomes this difficulty.At present,the main problem of sensorless technology is that it is impossible to adopt one control strategy to complete the operation control of the motor at the full speed range.Therefore,this article focuses on different motor control strategies and how to achieve smooth switching between them.The main research contents are as follows:(1)The structure,mathematical model and vector control method of permanent magnet synchronous motor are briefly analyzed and verified by simulation experiments.(2)The initial position detection method of the permanent magnet synchronous motor was proposed based on the high-frequency signal injection method.By collecting the high-frequency current response of the motor and using signal processing methods to extract the rotor position information,the traditional position observer is improved,the structure of the observer has been simplified.The low-speed starting control strategy of the permanent magnet synchronous motor based on the current / frequency(I / F)starting method is analyzed,and the parameter setting method of the current loop controller is given.With accurate initial position detection results and a starting strategy,successful motor startup was achieved.(3)A sensorless position estimation method for permanent magnet synchronous motors isdesigned using adaptive theory.An adaptive tuning law is designed using Popov hyperstability criterion and the stability of the system is verified.The speed loop controller of the motor vector control system is designed based on the sliding mode control theory,which improves the robustness of the system.The rotor position tracking estimation and motor operation control are realized.(4)Aiming at the problem that different sensorless control methods are suitable for different speed ranges.A switching function based on the current manager is designed to complete the smooth switching of the motor from low-speed start-up control to high-speed sensorless control.The stable operation of the motor at full speed was achieved.