自起动永磁同步电机转子铜耗分析的时步有限元优化离散策略

利用时步有限元方法对永磁同步电机进行转子铜耗分析计算时,由于空间中高次谐波磁场的作用,使得导条中的电流与损耗在集肤效应的影响下呈非均匀分布,于是有限元模性的空间离散方案将直接对计算精度产生影响。首先通过理论推导得出导条电流密度的解析表达式;在此基础上,通过建立不同形式的目标函数,研究等间距与不等间距条件下离散密度对于损耗计算精度的影响,及其所对应的最优离散方案;最后,针对转子实际槽形结构,在考虑交界面处强制引入节点的约束条件下,提出了采用分区域循环引用最优离散点的方法,求解全局优化离散策略。通过与时步有限元计算结果进行对比,验证了方法的合理性。

Optimization discrete strategy of time-stepping finite element for loss analysis in rotor bar of line-Start permanent magnet synchronous motor

When calculating copper loss in the rotor bar of permanent synchronous motor (PMSM) using time-stepping finite element method (T-S FEM),there are lots of high frequencies harmonic magnetic fields in the space,the current and loss density distributes non-uniformity because of skin effect,so the method of spatial discretization affects the computational accuracy directly.The current density expression was presented by theoretical deduction firstly,then the object function in different forms was established to research the computational accuracy under the condition of uniform and ununiform discretization,and the optimal discretization strategy was obtained.Finally,considering the constraint condition of the forced node in the interface of rotor bar,the method of optimal discretization calculating loop quoted in different regions was proposed to solve the global optimization problem.The rationality of method was validated by comparing with calculation result of T-S FEM.