基于电-热耦合模型的IGBT模块结温计算方法

温度循环下的疲劳累计损伤是IGBT模块失效的主要原因,计算IGBT模块的结温对预测其寿命具有重要意义。为了研究IGBT模块工作过程中结温变化情况,首先通过计算IGBT和FWD的功率损耗建立了IGBT模块电模型,然后在分析IGBT模块热传导方式的基础上建立了IGBT模块热模型,进而基于电模型和热模型建立了IGBT模块的电-热耦合模型,最后以三相桥式逆变器为例对IGBT和FWD的结温进行了仿真分析。结果表明,由于IGBT和FWD处于开关状态,两者的结温波形均呈波动形状,且波动均值经过短时间上升后稳定于一恒定值,所以逆变器用IGBT模块开始工作后经短时间的热量积累最终达到热稳定状态;由于IGBT的开关损耗比FWD大,使得IGBT结温受开关频率的影响较大。

Calculation Method of IGBT Module Junction Temperature Based on Electro-thermal Coupling Model

The main reason for the failure of IGBT module is fatigue cumulative damage under temperature cycles, and the calculation of IGBT module junction temperature is of great significance to predict the lifetime of the module. In order to study the change of IGBT module junction temperature under working, the electrical model of IGBT module was established by calculating the power loss of IGBT and FWD firstly. Then, the thermal model of IGBT module was built based on the analysis of IGBT module heat conduction mode, and electro-thermal model of IGBT module was built based on the electrical model and thermal model. Finally, the junction temperature of the IGBT and FWD were simulation analysis using the three-phase bridge inverter for example. The results show that the junction temperature waveform of IGBT or FWD wave shape because IGBT works in on-off state, and the wave mean of junction temperature stability to a constant value after a short time rising, so IGBT module for inverter achieve thermal stability after short time heat accumulation.The switching loss of IGBT is larger than that of FWD, so IGBT junction temperature is greatly influenced by the switching frequency.