基于开通密勒平台电压的IGBT模块结温估计研究

Study of IGBT Junction Temperature Estimation Based on Turn-on Miller Platform Voltage

已有研究表明,绝缘栅双极性晶体管(insulated gate bipolar transistor,IGBT)的可靠性与结温波动密切相关,如能准确地实时测量IGBT的结温,对可靠性的研究具有重要意义。依据温敏电参数法,该文提出一种基于栅极电压开通密勒平台的结温估计方法。首先分析IGBT栅极寄生电容的物理特性与温度的关系,得到栅极开通过程中密勒平台电压与结温线性相关;然后提出采用恒流驱动电路延长栅极电压开通过程中密勒平台持续时间,使其温敏感度与温线性度更高,可拟合出密勒平台值和结温间的线性关系;最后采用该方法对IGBT模块的结温估算进行实验验证,并与采用红外测温仪实时测量的结温进行对比,验证了所提方法的可行性和准确性。

It has been revealed that there is a closed relationship between the reliability and junction temperature of insulated gate bipolar transistor （IGBT）. If the junction temperature can be effectively measured in real time, the reliability of IGBT would be enhanced greatly. In view of this, a method based on the miller platform of turn-on gate voltage for junction temperature estimation of IGBT was proposed. The relationship between the electrical characteristic of gate and junction temperature was developed through analyzing the temperature related physical characteristic of gate parasitic capacitor. And then, a novel constant current driver was proposed to prolong the duration and enhance the temp-sensitivity and temp-linearity of the miller platform of turn-on gate voltage. Finally, the experiments of estimating junction temperature of IGBT using the proposed method and infrared thermometer were implied synchronously, the experimental results proved the feasibility and accuracy of the proposed method.