关键词: 永磁无刷直流电机, 端部磁钢, 三维有限元, 反电动势, 二维等效修正

Abstract: Permanent magnet brushless DC motor have been extensively applied in household appliances, industrial servo systems, and new energy vehicles due to their high operating efficiency and wide speed regulation range. However,the axial end magnetic field cannot be accurately modeled via conventional two-dimensional finite element simulation, which leads to a noticeable deviation between the simulated and measured no-load back-electromotive force( EMF) . In this paper,the extended permanent magnets at the rotor ends are taken as the research subject. A three-dimensional finite element simulation model is established to quantitatively analyze the influence of end magnets on the radial air-gap flux density and no-load back-EMF, and the end-field gain effects of motor prototypes with different core stack thicknesses are compared. To address the engineering challenges of heavy computational burden and time-consuming iterations in three-dimensional finite element simulation, a dimensionless correction coefficient for the end magnets is proposed, and a fast two-dimensional equivalent calculation model is constructed. Experimental validation on a prototype shows that the error between the twodimensional simulation results corrected by the proposed coefficient and the measured no-load back-EMF is within 1. 5%,which significantly reduces the simulation computational cost while maintaining accuracy.

Key words: permanent magnet brushless direct current motor, end magnetic steel, three-dimensional finite element, back-electromotive force, two-dimensional equivalent correctio