Permanent Magnet Linear Synchronous Motor Mover Position Estimation at Zero and Low Speed Using Eddy Current Loss Equivalent Resistance

In this paper, an alternative mover position estimation method of permanent magnet linear synchronous motor at zero and low speeds by using high-frequency (HF) signal injection is proposed. PMLSM usually adopts surface-mounted structure, which makes it not have significant saliency. Moreover, due to the long air gap of PMLSM, it is difficult to saturate the stator core with the injection HF signal to obtain the inductance-based saliency. The proposed method is to estimate the mover position by tracking the resistance-based saliency. By injecting HF pulsing voltage, eddy current loss in stator can vary as the mover is in different positions. The spatial variation of eddy current loss induces equivalent asymmetric resistances in mover estimation synchronous frame, which can be tracked as resistance-based saliency. A finite element analysis model of PMLSM is built to investigate the variation of eddy current loss and the saturation of stator when injecting HF voltage. A simulation model is used to verify the performance of resistance-based saliency in sensorless control.