电励磁爪极发电机气隙磁场与径向电磁力的解析计算模型

Analytic Model of Air Gap Magnetic Field and Radial Electromagnetic Force for Electric Excitation Claw Pole Alternator

爪极发电机因其特殊的转子结构导致磁场空间分布复杂,通常需要建立三维有限元模型对其进行计算分析。而三维有限元方法计算费时,且不便于分析发电机结构及电磁参数对磁场和电磁力的影响,因此提出一种气隙磁场与电磁力的解析计算模型。首先,考虑定子相电流谐波对气隙磁动势的影响及爪极倒角和定子开槽对气隙磁导的影响,建立气隙磁场的解析模型;在此基础之上,利用麦克斯韦应力张量法建立径向电磁力的解析模型,并依据解析模型对爪极发电机电磁噪声影响最大的36阶电磁力来源进行分析。所建解析模型的计算结果与有限元计算结果吻合,有限元结果得到了样机试验验证,从而说明了解析模型的准确性。

Three-dimensional finite element method（ FEM） is often used for electromagnetic field analysis of claw pole alternator due to its special structure. However,the effects of structural parameters on air gap magnetic field and electromagnetic force is undefined through FEM,which is highly time consuming. This paper presents a new analytic model of air gap magnetic field and electromagnetic force. The influence of phase current harmonic on magnetomotive force and the influence of rotor chamfer and stator slot on air gap permeance were considered to establish analytic model of air gap magnetic field. The electromagnetic force analytic model was derived from Maxwell stress tensor method. Based on the analytic model,the origin of 36 th order electromagnetic force,which had most significant influence on electromagnetic noise was analysed. The results calculated by analytic model are in agreement with the results of FEM,which are validated by a prototype test,that confirm the feasibility of the analytic model.