Sensorless Control Of Permanent Magnet Synchronous Traction Motor In Full Speed Range

Permanent magnet synchronous motor has the advantages of high power density and high torque density and has a good application prospect in the field of rail transit.High-performance control of permanent magnet synchronous motors requires accurate rotor position,which is usually provided by a mechanical position sensor mounted on the rotor.Additional mechanical sensors increase the size and cost of the system and reduce the reliability of the system,so sensorless control strategy is adopted.In this thesis,a full-speed sensorless control scheme is designed for high-power permanent magnet synchronous traction motor.Different position sensorless control strategies are adopted according to different operating conditions of the motor.At the static state,the rotating voltage injection initial position detection strategy is used.In the case of power-off during operation,the short circuit current vector method is used to determine the speed and rotor position at the time of restart.In the low-speed region,the high-frequency rotating voltage injection method is used,and the algorithm is improved for the high-power motor control system.An adaptive signal processing scheme is designed,which has a good effect of high-frequency current signal extraction.The sliding mode observer method is adopted in the high-speed region,which has good dynamic performance and robustness.Aiming at the switching problem in the sensorless control scheme,a double-hysteresis switching strategy is designed to avoid the problem of frequent start and stop of high-frequency signal injection and improve the stability of switching.Rotor position observation error is one of the indicators for judging the performance of PMSM position sensorless control.The observation error of the high-frequency rotating voltage signal injection method and the sliding mode observer method are analyzed.The influence of rotor position error on the electromagnetic torque by MTPA vector control is quantitatively analyzed,and the reference value of maximum position error is given.Next,the influence of rotor position error on the negative d-axis current compensation flux-weakening control is researched and proposed an optimization method for enhancing the stability of flux-weakening control.Based on dSPACE hardware-in-the-loop simulation platform,the verification of the position sensorless control scheme is completed.The improved high frequency rotating voltage injection method is compared with the traditional algorithm to verify its good filtering performance.Finally,the simulation results verify the impact of rotor position error to flux-weakening control.In the end,the experimental verification of the whole position sensorless control scheme is completed based on the 160kW direct-drive permanent magnet synchronous traction motor platform.The experimental results show that the control scheme designed in this paper has high position observation accuracy,good dynamic performance and strong robustness,and has high practical application value.