组合磁极无槽PMLSM正弦磁场分析

摘要

For the problem that non-sinusoidal air-gap magnetic field caused by the slot effect and the sin-gle pole of traditional permanent magnet linear synchronous motor ( PMLSM ) generates thrust ripple and affect the its performance, a structure of slotless PMLSM using modular pole was proposed to improve the sine degree of the magnetic field. The structure model of modular poles was established, and the superpo-sition of air-gap magnetic field was computed by layer model method. For eliminating the first three low frequency harmonic magnetic fields, the analytical method was used to analyze the relationship between the structure parameters and material characteristics when the air-gap magnetic field is sine wave, and to study the flux density, no-load EMF and harmonic magnetic field of the modular pole and single pole. The comparing results show that the 3rd, 5th and 7th are both equal to zero, the magnetic field and no-load EMF tends to sine wave when the width and remanence ratio of the modular poles satisfy assured constrains. The motor can effectively eliminate harmonic effects and improve its performance. The validity of theoretical analysis is proved by analytical method and FEM results.%针对传统永磁直线同步电机( PMLSM)齿槽效应及单一磁极产生的非正弦气隙磁场引起电机推力波动,使电机性能变差问题,提出一种组合磁极无槽PMLSM,以提高电机气隙磁场正弦度。建立了组合磁极结构模型,采用分层模型法将气隙磁场叠加,研究消除前三次低频次谐波磁场时,其正弦气隙磁场与电机结构参数及材料特性之间的解析关系式。对比分析了组合磁极和磁极未分段时的气隙磁密、空载反电势及其谐波磁场。研究结果表明当组合磁极中各段磁极长度、剩磁比例系数满足确定约束关系时,气隙磁场中三次、五次、七次谐波均为零,能使气隙磁密和空载反电势趋于标准正弦形,有效消除谐波影响,提高电机性能。解析法和有限元法结果一致证明了理论分析的正确性。