Research On Control System Based On Sensorless PMSM

Permanent Magnet Synchronous Motors(PMSM)are widely used in high-performance servo transmission systems due to their advantages of high performance-price ratio,high precision,and high power factor.In order to achieve closed-loop control,conventional permanent magnet synchronous motors use encoders,resolvers,and other mechanical sensors to obtain motor speed and position information.This not only increases the overall size and weight of the motor,but also impairs the system's practicality and stability,while limiting Its application in some harsh environments.In order to overcome the disadvantages of mechanical sensors,position sensorless control came into being.This article mainly focuses on surface-mounted permanent magnet synchronous motors.The specific work is as follows:This paper firstly introduces the research status of sensorless control technology,and introduces the control strategies applicable to medium-high speed range and low speed range respectively.Then the core of vector control of permanent magnet synchronous motor—coordinate transformation is introduced.Mathematical Model of Permanent Magnet Synchronous Motor in Different Coordinates.Based on this,a model of double closed-loop speed control system for permanent magnet synchronous motor speed and current was established.Secondly,the basic principles of the chirp signal injection method and the sliding mode observer method are introduced.The system uses the pulsed high-frequency voltage injection method in the low-speed domain.According to the principle of the algorithm,the initial position of the rotor is detected and the control performance of the rotor position observer is improved according to the saturation principle of the magnetic circuit.The system uses the sliding mode observer method in the high speed domain.The principles of sliding mode variable structure control and traditional sliding mode observers are discussed.The traditional observer's existing problems such as buffeting,imprecise velocity estimation and phase delay are improved.In MATLAB,the traditional and improved sliding mode observers are discussed.The simulation and comparison analysis confirmed that the improved sliding mode observer has higher accuracy in estimating the rotor position and velocity and better observation results.Finally,based on a single control strategy,sensorless precise control in the full-speed domain cannot be achieved.In this paper,the improved sliding mode observer is combined with the pulse high-frequency signal injection method,and the two control strategies are switched using the weighting function to achieve the rotor position.Double-closed loop speed sensorless position control.The simulation results show that there is no significant fluctuation in the speed waveform in the switching interval,and the purpose of smooth transition is achieved.The correctness and effectiveness of the control algorithm are verified.