Research On Sensorless Control Strategy Of Built-in Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors are used in more and more occasions because of their good speed regulation performance and high power density in AC servo systems,especially in the field of servo drive systems and efficient power output.With the continuous improvement of traditional motor control methods,the control accuracy and output dynamic performance of permanent magnet synchronous motors have been greatly improved.And now more and more intelligent control methods are applied,such as fuzzy control,sliding mode control and neural network control,etc.These control methods can obtain better demand results for different control objects.At the same time,the high-performance control of permanent magnet synchronous motors also requires feedback of motor speed and rotor position information.Current research on position sensorless control can not only reduce costs,but also enhance the reliability of permanent magnet synchronous motors in harsh environments,so it has great research significance for position sensorless control.This article takes the built-in permanent magnet synchronous motor as the research object,and first analyzes its structural characteristics and the superior performance of this motor.Based on this,a mathematical model is established,and a double closed-loop vector control system of a permanent magnet synchronous motor is established by means of coordinate transformation.Because the built-in permanent magnet synchronous motor has different direct and quadrature axis inductances,it is not suitable for the control method of_di=0.The maximum torque-current ratio control(MTPA)is designed by the formula method.Then,the reluctance torque can be fully used to improve the output capacity of the motor by properly controlling the value of i_d.And the speed feedback control adopts sliding mode control,which can enhance the robustness of the system and improve the speed regulation ability,but the sliding mode control will also cause the system chatter.In order to solve this problem,this article will introduce the idea of fractional order to make the system reach the stable state more quickly and have less chattering,then resolve the contradiction between the approaching speed of the system response and the degree of chattering.This method is also applied to the position sensorless observer module,and a fractional sliding mode observer is designed.Based on the design of these methods,high-performance control of the permanent magnet synchronous motor is achieved,and the speed and rotor position’information are accurately obtained.In the end,a permanent magnet synchronous motor control experiment with DSP28335 chip as the core is set up,and an intelligent power module(IPM)is used as the drive board.The main hardware circuits during the experiment are designed,the function of related hardware circuit is introduced in detail,and the design flow of subroutine in software is described.Based on the software and hardware design,an experimental platform for permanent magnet synchronous motors is established.After that,the closed-loop simulation model built in Simulink was used to generate code,and it was compiled and optimized in Code Composer Studio(CCS)software to obtain the control code that can be embedded in the DSP chip.Finally,relevant experimental test analysis was performed.