IGBT封装形式对结温测量精度的影响

Influence of IGBT Package Types on the Accuracy of Junction Temperature Measurement

高压大功率绝缘栅双极型晶体管(IGBT)器件的不同封装形式(压接型IGBT器件和焊接式IGBT模块)使其热学特性尤其是散热路径存在很大差异,最终可能会影响结温测量方法的适用性和准确性。基于有限元法建立了可表征压接型封装和焊接式封装的等效热学仿真模型,详细研究了小电流下饱和压降结温测量法的物理过程,对比分析了两种封装形式结温测量的精确度。仿真结果表明,小电流下饱和压降结温测量法存在固有测量误差的问题,在高压大功率IGBT模块中尤为突出,但是由于压接型IGBT器件双面散热的特性使芯片内部温度分布更均匀,也使结温测量的误差相对较小。

The thermal characteristics between press pack insulated gate bipolar transistors (PP IG- BTs)and IGBT modules are different,especially the thermal dissipation path,due to their different package types.This distinction may affect the applicability and accuracy of the existed method of junction temperature measurement.Based on the finite element method,an equivalent thermal simulation model was established,which was used to characterize the two package types (PP IGBTs and IGBT modules). The physical process of junction temperature measurement using saturation voltage drop at small constant current was studied in detail,and the accuracies of junction temperature measurement methods between the PP IGBTs and the IGBT modules were compared.The simulation results show that the junction tem- perature measurement method using saturation voltage drop at small constant current has the inherent measurement error,especially for high-voltage and high-power IGBT modules.However,due to the doub- le-sided cooling characteristic of PP IGBTs,the internal temperature distribution of the chip is more uni- form and this leads to a relatively smaller error of the junction temperature measurement.