IGCT过应力关断下动态雪崩诱发的电压自箝位效应

Voltage Self-Clamping Effect Induced by Dynamic Avalanche at Over-Stress Turn-off of IGCT

作为高压功率器件,集成门极换流晶闸管(IGCT)关断过程中必然发生的动态雪崩效应是限制器件反偏安全工作区(RBSOA)的重要因素。通过建立能更好地反映电流集中效应的多单元仿真结构模型,对IGCT过应力条件下的关断特性进行了仿真,发现了一种与开关自箝位模式(SSCM)非常相似的电压自箝位效应。然而,与SSCM不同的是,这种自箝位效应是由动态雪崩效应诱发的。在强烈的动态雪崩下,雪崩产生的载流子与被移除的载流子达到了动态平衡,耗尽区电场无法展宽导致了电压箝位。由于自箝位期间雪崩产生的电流丝无法快速移动,器件极易因局部过热而损毁。并且,随着器件电流增益的增大,这种效应更容易发生。研究结果可为IGCT提供更清晰的RBSOA。

As a high-voltage power device,the dynamic avalanche effect that inevitably occurs during the turn-off process of the integrated gate commutated thyristor(IGCT)is an important factor limiting the reverse bias safe operation area(RBSOA)of the device.By establishing a multi-cell simulation structure model which can better reflect the current crowding effect,the turn-off characteristic of IGCT under over-stress conditions were simulated,and a voltage self-clamping effect that is very similar to the switching self-clamping mode(SSCM)was found.However,this self-clamping effect,different from SSCM,is induced by dynamic avalanche effect.Under strong dynamic avalanche,a dynamic equilibrium can be reached between the carriers generated by the avalanche and the removed carriers,consequently the electric field in the depletion region is unable to extend,leading to the voltage-clamping.The avalanche-generated current filaments cannot move quickly during self-clamping,which is very likely to damage the device due to local overheating.Moreover,this effect is more likely to occur as the current gain of the device increases.The research results can provide a clearer RBSOA for IGCT.