Sensorless Control of Permanent-Magnet Linear Synchronous Motor Based on Modified Linear Extended State Observer

Abstract

Permanent-Magnet Linear Synchronous Motor (PMLSM) transforms electric energy into linear mechanical kinetic energy without transmission mechanism which is widely used in rail transmit due to its merits of high efficiency, relatively low losses and simple mechanism. In the field oriented control of the linear motor, high-precision speed and position information are required. However, the installation of the linear grating increases the cost and complexity of the system, reduces anti-disturbance ability for mechanical structures, which may directly affect the control performance. In this paper, based on the sensorless control method, a modified linear extended state observer (MLESO) is proposed and utilized to estimate the back electromotive force. Then, the linear active rejection disturbance control (LADRC) is used to estimate and compensate system dynamics and disturbances to enhance disturbance rejection and stability of the PMLSM system. Moreover, the feedforward controller (FFC) is introduced to improve the response speed of the PMLSM. The simulation results certify that the proposed strategy has the superiority to the conventional sensorless control method.