Research On Position Sensorless Vector Control Technology Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)has many advantages such as low temperature rise,high efficiency and energy saving.Due to the rapid development of modern ac motor frequency control theory and power electronics technology,PMSM is widely used in household appliances,industry,national defense and aerospace and other fields.In order to control the PMSM with high performance and precision,the traditional method is to install the photoelectric encoder,magnetic encoder and rotary transformer to detect the speed of the motor and the magnetic pole position of the rotor.The existence of mechanical sensors will increase the volume,cost and complexity of the control system and make it difficult to use in high temperature and harsh environment.In order to overcome the above shortcomings,research on sensorless control technology has become a hot topic.Based on domestic and foreign research on sensorless control methods of permanent magnet synchronous motors,this paper takes the built-in permanent magnet synchronous motors as the research object,and establishes a mathematical model of permanent magnet synchronous motors in a synchronous rotating coordinate system.The tuning is designed,the specific implementation process of the SVPWM algorithm is analyzed.In order to solve the problems such as poor tracking effect,low accuracy and even failure in the low speed range based on the motor fundamental wave model position sensorless control algorithm,the high frequency signal injection method is used to solve it.Based on the in-depth study of the theory of pulsed high-frequency voltage signal injection method,the rotor initial position detection method was designed by using the flux linkage saturation characteristics of permanent magnetmotors.For the high-frequency signal injection method in medium and high speed sensorless control,the estimation accuracy is reduced and the dynamic performance is degraded.The model reference adaptive method based on the fundamental wave model of the motor is used to solve the problem.The adaptive rate was derived,and the stability of the nonlinear feedback system was proved according to Popov's theory of superstability.The composite observer is designed by using the weighted average algorithm,which can smoothly switch the pulsed high frequency voltage signal injection method and the model reference adaptive method,and then realize the position sensorless control of the permanent magnet synchronous motor in the full speed range.The above control method builds a simulation model under MATLAB / Simulink environment to verify the theory and feasibility of the sensorless hybrid control method.Using the main control chip TMS320F28335 as the control core to build a permanent magnet synchronous motor position sensorless experimental platform,the hardware circuit and software program are designed,and the experiment is carried out on a 1.5k W motor.The experimental results show that the control method is at low and medium and high Both can obtain better control effect and higher precision,which further verifies the validity of the theoretical analysis.