短初级、长次级的直线感应电机,因其可靠性高、结构简单、控制方便,广泛应用于城市轨道交通系统.针对直线电机磁场复杂、边缘效应明显等缺点,参考旋转感应电机理论,提出适合直线感应电机运行的一种特殊结构的栅格型次级.通过对栅格型次级等效电路的分析,详细推导出电机主要参数的计算公式,并且分别从三维有限元分析模型仿真、样机实验两方面进行了验证.结果表明,栅格型次级能规范感应涡流的路径、消除直线感应电机的第二类横向边缘效应、提高直线电机推力特性.并且验证了采用等效电路法分析直线电机的有效性和实用性,为准确计算特殊次级结构的直线电机提供了理论与实践依据.
Linear induction motor(LIM)with short primary and long secondary has been widely used in subway transportation for its high reliability,simple structure and convenient control.In view of the com-plex electromagnetic field and obvious edge-effects of LIM, this article presented a special ladder type secondary which was suitable for the operation of LIM by referencing the design theory of the rotating in-duction motor.The main parameter formulas of the LIM with ladder secondary were analysed particularly based on the equivalent circuit method,then three dimensional(3D)finite element method(FEM)sim-ulation and prototype experiments were implemented to verify the rationality of the analysis and calculation method separately.The results showed that the ladder secondary can standardise the induced eddy current path,eliminate the second transversal edge-effects, and improve the thrust characteristics.The conclu-sion verifies the effectiveness and practicability of the equivalent circuit method to calculate the motor per -formance and provides theoretical and practical basis for the future investigation of LIM with special sec-ondary structure.