SiC逆变器高频脉冲电压对Hairpin绕组绝缘安全的影响分析

Influence Analysis of High Frequency Pulse Voltage of SiC Inverter on Insulation Safety of Hairpin Winding

针对碳化硅(SiC)逆变器高频高dv/dt脉冲激励下的Hairpin绕组高电应力容易造成绝缘损伤的问题,该文对一台电动汽车用Hairpin绕组永磁同步电机进行了绕组匝间绝缘的电压应力计算与安全分析。首先,提出考虑双导体边耦合效应的Hairpin绕组单匝线圈高频等效电路模型,提取电机绕组的高频分布参数,并基于场路耦合有限元方法建立Hairpin绕组的匝间电压计算模型;然后,得到SiC逆变器驱动下的绕组匝间绝缘电压应力,利用绕组匝间电压测试平台验证了模型与分析方法的正确性;最后,分析了不同匝间电压幅值、绝缘厚度、材料相对介电常数、匝间气隙长度等对气隙电场分布线的影响规律,以气隙电场分布线与Paschen曲线的关系为判据,给出了一种判断绕组绝缘是否发生放电的方法。

In order to solve the problem of insulation damage caused by high voltage stress of Hairpin winding under high frequency and high dv/dt pulse excitation of SiC inverter,the voltage stress calculation and safety analysis of inter-turn insulation of a permanent magnet synchronous machine with Hairpin winding for electric vehicle are carried out in this paper.Firstly,the single-turn equivalent circuit model of Hairpin winding considering the coupling effect of two conductor sides is proposed,the high-frequency distribution parameters of motor winding are extracted,and the inter-turn voltage calculation model of Hairpin winding is established based on the field-circuit coupling finite element method.Then,the inter-turn insulation voltage stress of the windings driven by the SiC inverter is obtained,and the correctness of the model and analysis method is verified by using the inter-turn voltage test platform.Finally,the influences of inter-turn voltage amplitude,insulation thickness,relative dielectric constant of materials and inter-turn air gap length on the distribution line of air gap electric field are analyzed.Based on the relation between the electric field distribution line of air gap and Paschen curve,a method to judge whether the insulation of winding discharges is presented.