并联IGBT芯片的等离子体抽取渡越时间振荡机理及其特性分析

摘要

大功率 IGBT 器件内部通常由多个芯片并联实现大电流.并联 IGBT 芯片在关断的拖尾阶段存在高频等离子体抽取渡越时间(PETT)振荡,这种振荡会对环境、驱动电路产生严重的电磁干扰.针对空穴注入空间电荷区后引起的空间电荷效应,首次分析空间电荷区的小信号特性,研究IGBT芯片自激振荡产生的原因,揭示高频PETT振荡的机理.其次,研究并联IGBT芯片之间寄生电感与产生 PETT 振荡时集射极电压的相互关系,基于理论方法计算振荡电压范围以及振荡频率的特点.最后,搭建IGBT开关特性测试平台,对并联IGBT芯片的PETT振荡特性进行测试.实验结果表明,PETT振荡不是随机产生,振荡产生的时刻与集电极电流具有一定的相关性;并联 IGBT 芯片振荡电压的范围与理论计算范围相吻合;并联 IGBT 芯片振荡频率的范围也与理论计算范围相吻合.因此,实验结果验证了对PETT振荡特性分析的正确性.%High power IGBT usually contains several IGBT chips to obtain a high current handling capability. Plasma extraction transit time (PETT) oscillation exists in the tail phase during the turn-off process of paralleled IGBT chips, which causes serious electromagnetic interference to the environment and drive circuit. At first, the small signal characteristic of space charge region caused by injection of carriers is analyzed in this paper. Then, the relationship between package parasitic inductance and oscillating voltage range is investigated, the oscillation voltage range and frequency are deduced based on theoretical analysis. At last, an IGBT dynamic test platform is built, and the PETT oscillation characteristics of two paralleling IGBT chips are studied. Experimental results indicate that PETT oscillation is not randomly generated, which has certain relevance with collector current value.In addition, the experimental results are in agreement with the calculated results for oscillation voltage range and oscillation frequency. Therefore, the correctness of the analysis of PETT oscillation characteristics is verified.