基于RC阻容吸收的串联IGCT动态均压研究

为了研究串联IGCT关断时暂态特性,建立了串联IGCT的关断电流数学模型,该模型考虑了所串联的同一型号半导体开关器件物理特性存在的细微差异。基于此模型,提出了用微分方程研究串联IGCT电路关断的均压特性的思路。为验证该思路的有效性,建立了基于串联IGCT斩波电路的关断暂态模型,该模型充分考虑了IGCT阻容吸收回路、线路杂散电感对IGCT关断暂态过电压的影响。数值仿真及试验结果表明,该模型能较好地反映串联IGCT关断的均压情况。

Transient Voltage Sharing of Series Connected IGCTs Paralleld with RC-snubbers

The design of the Integrated Gate Commutated Thyristor(IGCT)and the commutation inductance of the drive influencing the dynamic over-voltage in the current source inverter(CSI)were presented.Different semiconductor design tools to reduce dynamic over-voltage were described and the impact on other parameters such as device losses was analyzed.Differences between the application in CSI and voltage source inverter(VSI)were widely discussed.Based on the IGCT,the series connection of power devices is necessary for obtaining 6 kV output voltage in neutral point clamped(NPC)three-level high power medium voltage drives(MVDs).As the process of the transient turn-off is very complex,in order to discuss the transient turn-off characteristics of series connected IGCTs,their corresponding turn-off transient current models are developed with the different performances in this paper.According to the current models,the method using differential equations to study the voltage sharing during IGCTs' turn-off transients is proposed.This paper uses a mathematics method to calculate the turn-off transient voltage of the connected IGCTs.Consequently,the turn-off transient model based on the chopper circuit is deduced to confirm its efficiency,in which the RC-snubbers of IGCT,stray inductance are analyzed.Simulation and experimental results show the model based on the proposed method can well describe the turn-off voltage sharing of series connected IGCTs.