Research On PMSM Position Sensorless Vector Control System

With the application of power electronic technology in the control system becoming more and more mature and popular,permanent magnet synchronous motor(PMSM)plays an important role in all walks of life.Compared with the direct-current motor,permanent magnet synchronous motor has no brush and commutator,which has the advantages of simple structure,safe and reliable operation;compared with the asynchronous motor,permanent magnet synchronous motor has no excitation winding on the rotor,and the permanent magnet is used to produce the magnetic field,which has the characteristics of low loss,high efficiency and high power factor.Because of the advantages of permanent magnet synchronous motor,it is still the mainstream trend during the 13 th Five-Year Plan period,and PMSM is widely used in the field of new energy vehicles,rail transportation,elevator,medical machinery,household appliances industry and marine electric propulsion.In order to realize the high precision control of the motor,PMSM is often combined with power electronic drive technology and micro electronic control technology,which is the main direction of the development of the motor in the future.For the purpose of controlling the speed and torque of permanent magnet synchronous motor accurately,high quality position / speed sensor is an integral part of the closed-loop control system.However,the existence of position / speed sensor not only increased the complexity and cost of the system,but also reduced the robustness of the system.In order to avoid a series of problems caused by position / speed sensor,the speed identification method without position / speed sensor can be used instead of the position / speed sensor to obtain speed information.Therefore,the sensorless control technology of permanent magnet synchronous motor has become this focus of current research.This paper studies the problem and the research contents are as follows:1.The vector control system of permanent magnet synchronous motor is studied in this paper and the permanent magnet synchronous motor vector control procedures is modified and improved.The starting performance of the motor is improved,the speed range of the motor is enlarged,and the experimental results are further enriched.2.The basic working principle of model reference adaptive algorithm is analyzed,the expression of speed identification based on the algorithm is deduced,and the sensorless control strategy is realized.The model of the control system is established under MATLAB/Simulink,and the motor speed is identified under different operating conditions.The results show the feasibility and accuracy of the speed identification algorithm based on MRAS.3.The expression of the speed identification is simplified.An improved speed identification expression based on MRAS is obtained.And the advantages and disadvantages of the algorithm are analyzed by simulation experiments.4.On the basis of voltage closed loop flux weakening using the gradient descent method,the expression of speed identification based on model reference adaptive is applied to the weak magnetic field.Simulation results show that the speed identification algorithm is feasible in the weak magnetic field.5.The experimental platform has been further improved.On the basis of motor vector control program,the program of speed identification algorithm is written and the control strategy of position / speed sensorless is realized.The experimental results verify the correctness of the speed estimation method based on model reference adaptive.