柔直用压接型高压IGBT导通压降演化规律研究

Study on Evolution Law of Conduction Voltage Drop of Clamping Type High Voltage IGBT for Flexible Direct Application

MMC子模块中的高压功率器件绝缘栅双极型晶体管(insulated gate bipolar transistor,IGBT)在长期运行工况下逐渐发生热老化,最终导致器件失效。因此,研究IGBT的状态监测技术对于MMC的可靠运行具有重要意义。目前的文献压接型IGBT导通压降演化规律研究较少,文中搭建了压接型IGBT功率循环试验平台,并在功率循环试验过程中同时监测得到不同热老化程度下的器件导通压降和门极电流,利用试验得到的结温与门极电流的线性关系将导通压降归一化到同一结温下,从而剥离结温对导通压降的影响。结果表明,导通压降随着热老化程度呈现上升的趋势,变化范围大致在10%以内。最后,将老化失效的两个IGBT解体,发现器件内部物理结构发生变化,芯片表面发现局部烧蚀甚至熔化。

The insulated gate bipolar transistor(IGBT for short),the high voltage power element in MMC submodule,becomes gradually thermal aging at long⁃term operating conditions and eventually leads to failure of the element.Therefore,the study of status monitoring technology of IGBT is of great significance for reliable operation of MMC.The study on evolution law of conduction voltage drop of clamping type IGBT in the present literature is less.In this paper,a power cycle test platform for the clamping type IGBT is set up,the conduction voltage drop and gate current of the element at different thermal aging degree is monitored simultaneously during the power cycle test period.The linear relation between the junction temperature and the gate current,which is obtained by the test,is used to normalize the conduction voltage drop into the same junction temperature,thus removing the influence of junction temperature on the conduction voltage drop.It is shown by the result that conduction voltage drop shows the upward trend with the degree of thermal aging and the variation range is within approximately 10%.Finally,two aged and failed IGBTs are disassembled and it is found that the internal physical structure of the devices has changed and local ablation or even fusion happened on the chip surface is founded.