3-D FE Analysis of Magnet Segmentation for Optimizing Thrust Force and Eddy Current Loss of Arc Linear Servo Motor

Abstract

When employing high-magnetic co-energy sintered NdFeB magnets, permanent magnet linear synchronous machines (PMLSMs) exhibit several advantages over traditional induction and direct current machines, including greater thrust capability and efficiency. However, during operation at high frequencies, significant eddy current losses in the permanent magnet (PM) can result in elevated temperatures, increasing the risk of irreversible demagnetization. This issue is further compounded by the large air gap in such machines, making the thrust force a critical factor for ensuring efficient performance. A complete magnet segmentation (CMS) can be an effective method for reducing the PM eddy current losses, but it reduces the thrust characteristics and mechanical robustness of the PMLSM. Therefore, a partial magnet segmentation (PMS), namely, single-side PMS (SSPMS), is studied for the new arc-structured PMLSM to optimize the eddy current loss and thrust force. A comparison between the initial PM, CMS, and SSPMS is performed using the Ansys Maxwell 3-D finite element analysis (FEA) tool. The results demonstrate that the SSPMS configuration significantly reduces PM eddy current loss while maintaining the same thrust force. Moreover, it offers superior mechanical robustness and lower manufacturing costs compared to the conventional CMS.