车用SiC电机驱动控制器用金属化膜电容研究

Research on Metallized Film Capacitor of SiC Motor Control Unit for Electric Vehicle

当功率模块使用碳化硅(silicon carbide,SiC)电子器件,其体积已大幅缩小,为实现控制器的高功率密度,需降低电容器体积。该文首先建立电容器设计参数和电机驱动控制器需求之间的函数关系,从理论层面指出电容器的设计要求。通过集成水冷散热器的封装结构,降低电容器热阻,从而进一步提升电容器吸收波纹电流的能力。通过仿真验证表明,在相同损耗下,优化电容器平均温度较普通封装电容器平均温度下降30.7%。制造样件并测试,优化后电容器在相同损耗下较普通电容器热阻下降了72.4%;吸收纹波能力从180Arms提升到398Arms,纹波电流提升了2.2倍。改进使电容器具有较高的纹波电流提供能力,有效减少了电容器的体积,实现了SiC控制器功率密度提升及高频特性的要求。

The size of a motor control unit(MCU)was remarkably reduced when the Si-based power electronics was replaced by the silicon carbide(SiC)counterpart.In order to achieve the goal of high-power density,it is necessary to reduce the volume of the capacitor.In the paper,the functional relationship between the design parameters of the capacitors and the requirements of the MCU was established,and the design requirements of the capacitors were pointed out.The thermal resistance of the capacitor was reduced by using the innovative packaging structure featured with internal water cooling,which further improved the ripple current rating of the capacitor.The simulation results show that the average temperature of the optimized capacitor is 30.7%lower than that of the baseline capacitor.The optimized capacitor was manufactured and tested.After optimization,the thermal resistance of the capacitor decreases by 72.4%,and the ripple current rating of capacitor increases from 180 Arms to 398 Arms.The experiments show that,the improved capacitor can provide higher ripple current.This method proposed in the paper can effectively reduce the volume of the capacitor,and achieves the improvement of power density.