涡流制动特性试验的纵向端部效应研究

Research on the longitudinal end effect in eddy-current braking characteristic experiment

涡流制动台架试验是研究涡流制动特性的重要手段,当试验使用的磁极个数少于设计数量时,纵向端部效应对试验结果有显著影响,故应对纵向端部效应的产生机理及修正方法进行深入研究。文章设计不同磁极个数的试验方案,验证端部效应对制动力和动态吸力的影响。通过2-D有限元电磁仿真,获得涡流制动磁场、涡流密度及洛伦兹力的分布规律,分析端部效应的产生机理。计算不同速度下,各磁极产生的制动力,获得端部磁极对制动力的贡献度,进而推导出端部效应的修正公式。研究结果表明,端部效应对动态吸力的影响较小,对制动力的影响比较显著,因此只需对制动力进行修正;入端磁极的制动力与中间磁极几乎相同,出端磁极的制动力相对较小,且对制动力的贡献与速度近似线性相关;通过出端磁极贡献度函数修正制动力试验数据,修正结果与3-D有限元仿真制动力的相对误差显著减小。研究结果为涡流制动试验设计和试验数据处理提供参考,有利于掌握更准确的涡流制动特性,从而指导产品研究开发。

Bench experiments play a crucial role in studying the eddy-current braking characteristics.The longitudinal end effect significantly influences experimental results,when the number of magnetic poles used in these experiments is below the design level.Therefore,studying the generating mechanism of this effect and correction methods become imperative.This study introduced experimental schemes with varying magnetic pole counts to verify the influence of the end effect on braking force and dynamic attractive force.The study employed 2-D finite element electromagnetic simulations to extract the distribution patterns of the magnetic field,eddy current density,and Lorentz force,elucidating the generating mechanism of the end effect.By calculating the braking force of individual magnetic pole at different speeds,the study inferred the contribution of the end magnetic pole to the braking force,deriving the correction formulation of end effect.The study results show that a minor influence of the end effect on the dynamic attractive force,while a significant impact on the braking force,necessitating correction solely for the braking force.The braking force of the leading pole is identified nearly equal to that of the intermediate pole,while that of the trailing pole is lower and its contribution is approximately linearly related to speed.By correcting the braking force experimental data using a trailing pole contribution function,a notable reduction in the relative error between the correction results and the braking force derived from 3-D finite element simulations is observed.The research findings serve as a reference for the design of eddy-current braking experiments and the processing of experimental data.This enhancement contributes to a better comprehending of accurate eddy-current braking characteristics,thereby offering guidance in product research and development.