Research On Speed Sensorless Direct Torque Control Strategy Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)is widely used in AC drive and servo control because of its advantages such as high efficiency,small size and low temperature rise.In the motor speed control system,the speed information is acquired by mechanical sensors,but the mechanical sensor device will not only increase the cost of the system,but also be affected by the environment during the signal transmission process.In recent years,due to the continuous improvement of the application environment and performance requirements of AC speed regulation systems,speed sensorless control technology has become one of the current research hotspots.This paper deeply researches and improves the speed sensorless direct torque control algorithm of PMSM.The specific research content is mainly divided into the following 4parts.1.Aiming at the problems existing in traditional mechanical sensors of PMSM,a model reference adaptive algorithm is used to estimate the speed.The simulation results prove that the estimated speed under the model reference adaptive algorithm can track the motor speed in real time,verify the effectiveness of the model reference adaptive algorithm,and solve the problems of instability,difficult maintenance,and high cost of the traditional mechanical sensor.2.Aiming at the problem that the stator resistance is susceptible to the sudden change of temperature and current,which leads to deviations in speed estimation.On the basis of the speed sensorless control system,a model reference adaptive algorithm is used to identify the stator resistance value online,and the identification value is then used for speed estimation.The simulation results show that this method effectively reduces the influence of stator resistance changes on the speed estimation accuracy,improves the accuracy of the model reference adaptive algorithm for speed estimation,and reduces the calculation error.3.Aiming at the problem that the PI regulator in the traditional direct torque control system is not robust and cannot meet the requirements of rapidity and low overshoot at the same time,an regulator based on auto disturbance rejection control technology is adopted,and the technology is expanded to the state observer.The nonlinear function in is replaced with a linear function,which simplifies the calculation process on the premise of achieving the same effect.The results show that on the basis of the estimated speed following the real speed in real time,the auto rejection regulator plays a role in enhancing the robustness and rapidity of the system.4.The speed sensorless direct torque control algorithm based on the PI regulator and the auto disturbance rejection regulator were verified on the experimental platform of the AC speed control system of PMSM with STM32F103 as the main control chip.The program of A/D sampling,coordinate transformation,auto disturbance rejection control algorithm and model reference adaptive control algorithm have been written for PMSM speed sensorless direct torque control system.The software program of the controller has been written and debugging.The results of this paper are compared with the motor speed response waveform of direct torque control of PMSM under traditional mechanical sensors.The experimental results show that the control algorithm of this paper can achieve the function of mechanical sensor and enhance the stability of the control system.