Optimization Analysis and Performance Study of PM Eddy Current Loss of Permanent Magnet Synchronous Motor

ABSTRACT The interior permanent magnet synchronous motor (IPMSM) for vehicles has advantages of small size, high power, high efficiency, high integration, and large speed range. However, due to its closed structure and the permanent magnets (PMs) used being NdFeB with good conductivity and poor heat resistance, when the magnetic field alternates, eddy currents are generated inside the PMs, causing eddy current losses and further leading to a serious temperature rise, even causing irreversible demagnetization of the PMs, which is fatal for the safe operation of IPMSM for vehicles. Therefore, it is necessary to analyze and study the eddy losses of PMs and explore methods to reduce them. Firstly, this paper analyzes the mechanism of eddy losses in PMs and establishes a finite element parameterized model to analyze and compare the effects of parameters such as pole slot fit, rotor structure, air gap length, stator slot width, stator skew slot angle, and the number and type of PM segments on eddy losses. The research results indicate that reasonable pole slot matching, V‐type PMs, increasing air gap length, reducing stator slot opening width, and increasing stator skew slot angle can effectively reduce the eddy losses of PMs. Secondly, based on this, the focus is on analyzing and researching the segmented reduction of eddy losses in PMs. Segmenting the PM can increase the equivalent impedance of the eddy current circuit, thereby reducing eddy losses. Simulation analysis is conducted on the eddy losses of PMs with different numbers and types of segments, and it is verified that the eddy losses of PMs decrease with the increasing number of segments. Finally, based on the segmentation of the PM, the parameters such as air gap length, stator slot opening width, and stator skew slot angle are further optimized to effectively reduce the eddy loss of the PM, obtaining good optimization results.