Research On Position Sensorless Permanent Magnet Synchronous Motor Model

As the permanent magnet synchronous motor has simple structure, high power density, large torque coefficient, so it has gradually take the place of DC motor and step motor, is widely used in all kinds of high precision and high stability, and becomes the mainstream of nowadays servo system.Vector control system generally uses the speed and current double closed-loop control structure. In the traditional speed loop, in order to obtain the rotor speed and position feedback, usually by sensors installed in the rotor continuous detection of rotor speed and position. However this method not only increases the cost of design, limits its use in harsh conditions, but also increases the volume of AC motor, therefore this thesis focused on the topic of permanent magnet synchronous motor sensorless vector control system.The thesis firstly establishes the permanent magnet synchronous motor mathematical model in three different coordinate, then analyzes the permanent magnet synchronous motor vector control principle and introduces several control methods. And in this thesis, the SVPWM modulation strategy and its implementation is expound. On this basis, the thesis uses MATLAB/SIMULINK to build the vector control of permanent magnet synchronous motor mathematical model.Then on this basis, the thesis presents the sensorless vector control principle model based on sliding mode observer, uses the sigmoid function to replace traditional sign function eliminating chattering problem of certain. In the estimation of the rotor position and speed, the thesis designs a kind of back EMF observation model to replace the traditional low pass filter method, avoiding phase delay caused by low pass filter, improving the accuracy of position and speed estimation. And simulated in MATLAB/SIMULINK, the simulation results show that the sliding mode observer has better anti-shake function, and has the accurate ability of rotor position estimation.