计及焊料层疲劳累积效应的IGBT模块寿命评估

Lifetime Evaluation of IGBT Module Considering Fatigue Accumulation of Solder Layers

作为大功率变流器的关键单元,绝缘栅双极晶体管（insulated gate bipolar transistor,IGBT）的高可靠性是系统稳定运行的重要保证,准确的寿命评估是提高系统可靠性的有效手段之一。然而,目前器件寿命评估多忽略焊料层疲劳造成的热阻、热载荷增大效应,易高估器件寿命。针对该问题,该文提出计及焊料层疲劳累积效应的IGBT模块寿命评估模型,该模型考虑焊料层失效位置信息以及疲劳造成的热特性反馈效应。首先,基于IGBT模块三维电–热–力多物理场耦合模型分析不同焊料层疲劳对模块热响应影响的差异;其次,提出基于Cauer模型的考虑焊料层疲劳位置信息的热网络更新策略;然后,基于该策略建立适时更新热网络的计及焊料层疲劳对模块老化加速作用的寿命预测模型;最后,与现有寿命预测模型对比分析实际风速下风机变流器中IGBT模块的寿命评估。

As the key component of converters, the reliability of insulated gate bipolar transistor （IGBT） is important to the stability of poWer electronic systems. Improving the accuracy of lifetime prediction model is an effective way to enhance the reliability of power electronic system. However, the effects of solder layer fatigue on thermal resistance and thermal loading are neglected in most existing lifetime evaluation models, which will seriously exaggerate lifetime of IGBT modules. Therefore, a lifetime estimation model, considering the accumulative effect of solder layer fatigue, was proposed in this paper. The model took into account the positive feedback of degradation on module aging process and the location information of failure solder layer. Firstly, the differences of effects of chip or DBC solder layer fatigue on thermal performance of IGBT module were investigated, based on the 3D finite element model. Then, a thermal network improving strategy, considering the location information of failure solder layer, based on Cauer equivalent thermal model was proposed. Thirdly, the update strategy was applied to build the more accuracy lifetime estimation model. Finally, the proposed model was used to estimate the service life of IGBT module applied in wind turbine and the result was compared with the existing lifetime estimation model.