柔直换流阀用压接式IGBT器件物理场建模及内部压强分析

Physical field modeling and internal pressure analysis of press-pack IGBT device based VSC-HVDC converter

压接式IGBT器件是柔性直流换流阀的核心,器件内部压强分布直接影响器件及系统可靠性,而内部压强又受各种材料及复合应力相互耦合作用,针对不同应力耦合效果及其对内部压强的影响,进行压接式IGBT器件物理场模型仿真以及器件内部最大压强分布趋势的研究。首先,基于3.3 kV/50 A压接式IGBT器件实际结构,建立了多物理场模型,分析了机械、机-热和机-热-电不同耦合模型下器件内部压强分布的差异,并获取了器件承受内部最大压强的薄弱环节及各种内部应力作用的耦合效果。然后,基于机-热-电耦合模型,分析了不同环境温度、外部压力、导通电流对压接式IGBT器件内部薄弱层最大压强及性能的影响。最后,建立了压接式IGBT器件功率循环平台,通过恒导通工况和功率循环实验验证了机-热-电耦合模型的有效性和薄弱层分析的合理性。研究结果表明,机-热-电耦合模型能更好地表征压接式IGBT器件多应力耦合作用效果,内部最大压强的薄弱环节为IGBT芯片与发射极钼层间,且内部最大压强随环境温度、外加压力和导通电流的增加而增加。

Press-pack IGBT device is the core of the VSC-HVDC converter,the pressure distribution inside the device directly influences the reliability of the device and the converter system,and the internal pressure is coupled by various materials and composite stresses in IGBT devices.According to different stress coupling effects and their influences on internal pressure,the physical field model simulation of press-pack IGBT device is carried out and the trend of maximum internal pressure distribution in the device are studied.Firstly,based on the actual structure of 3.3kV/50 A press-pack IGBT device,a multi-physical field model is established,and the difference of pressure distribution in the device under different coupling models of mechanical,mechanical-thermal and mechanical-thermal-electrical types is analyzed,and the weak layers of the device withstanding the maximum internal pressure and the coupling effects of various internal stresses are obtained.Secondly,based on the mechanical-thermal-electrical coupling mo-del,the influence of different ambient temperatures,external pressure and current values on the maximum pressure and performance of the internal weak layer of press-pack IGBT devices are analyzed.Finally,a power cycle platform of the press-pack IGBT device is established,and the validity of the mechanical-electrical-thermal coupling model and the rationality of weak layer analysis are testified by the power cycle experiments.The results show that the mechanical-thermal-electrical coupling model can be better used to present the performance of the press-pack IGBT device with the multi-stress mutual coupling effect.The internal maximum pressure weak layer is between IGBT chip and emitter molybdenum layer,and the internal maximum pressure is increased along with the increase of ambient temperature,external pressure and conduction current.