Research On Position Sensorless Vector Control Of PMSM Based On Sliding Mode Observer

Permanent magnet synchronous motor has the advantages of simple structure,small volume,reliable operation,high precision,strong adaptability,fast response and good performance.It occupies an important position in the AC speed control system.In the civil,military industry and aerospace field has been widely used,so the performance of permanent magnet synchronous motor has been increasingly demanding.Conventional permanent magnet synchronous motors use mechanical sensors to obtain electric speed and position information,which will not only increase the cost of the motor control system,but also make the motor susceptible to external interference and reduce the reliability of the operation.In order to overcome the mechanical sensor disadvantages,No sensor control technology came into being.In this paper,mainly uses the surface-mount permanent magnet synchronous motor as the research object.Based on the sliding mode observer,the position sensorless control method of the permanent magnet synchronous motor is studied,and the estimation method of rotor position and velocity is studied and improved.Firstly,the relationship between the mathematical model and the variable of the permanent magnet synchronous motor in different coordinate systems is established.The basic principle of vector control and several commonly used vector control strategies are studied.The vector control method based on the optimal theory of stator current is selected based on the advantages of different control strategies.A block diagram of double closed-loop control algorithm for permanent current synchronous motor speed is established.On this basis,the space voltage vector pulse width modulation technology is analyzed.Secondly,the theory of sliding mode variable structure control and the principle of traditional sliding mode observer are discussed.The problems such as buffeting of thetraditional observer,lack of accuracy and phase delay are analyzed,and the traditional sliding mode observer is improved for these problems the study.The improved sliding mode observer uses the saturation function instead of the original switching function to weaken the buffeting,using a variable cutoff frequency filter that follows the speed change to obtain a good filtering effect,and reduce the computational load when the rotor position is compensated.Instead of using the phase-locked loop module to extract the speed,position signal,improve the accuracy of estimation,effectively improve the observation effect.Finally,in order to verify the correctness and feasibility of the proposed method,the simulation model of the permanent magnet synchronous motor vector control system is established in the MATLAB environment.At the same time,the traditional observer and the improved observer algorithm model are established,and the simulation is carried out.The results show that the improved sliding mode observer has high accuracy and strong robustness,which proves its effectiveness and good performance.The hardware platform of the system is designed and the hardware module of the system is tested.The first part of the vector control experiment is completed,and the experimental platform is carried out for the subsequent position sensorless experiment.