ZnO压敏电阻在高压变频器过电压保护中的应用

基于IGCT串联中性点钳位三电平高压变频器过电压保护进行研究,首次提出了利用氧化锌(ZnO)压敏电阻对高压变频器进行过电压保护的方法。通过分析ZnO压敏电阻的各种放置位置和接线形式,得出了合理的设计方案。以逆变系统整体作为变频器过电压保护的对象,解决了单个电力电子开关器件过电压保护困难的问题。结合实际的变频器参数,详细分析逆变系统工作状态的耐压情况,设计了ZnO压敏电阻。通过Matlab/Simulink对过电压情况的仿真,验证了所设计的ZnO压敏电阻对中性点钳位三电平高压变频器过电压保护的有效性。本文所设计的ZnO压敏电阻已得到实际应用。

Application of ZnO Varistor in Overvoltage Protection of Neutral Point Clamped Three-level High Voltage Inverter

This paper researches on overvoltage protection of neutral point clamped(NPC) three-level high voltage inverter which is based on IGCTs in series.A method of using ZnO varistor is first proposed to protect inverters from overvoltage.Through analyzing the different locations and connection structures of ZnO varistors,a reasonable design method is found.Taking all the IGCTs and clamping diodes with RC snubbers as the protected part of inverter solves the problem of hard to do overvoltage protection of each power electronic switch device.The withstand voltage of the protected part is analyzed based on practical parameters,and the design of ZnO varistors is given.The simulation results based on Matlab/Simulink are show that ZnO varistor is available to avoid overvoltage of NPC three-level high voltage inverter.The designed ZnO varistor is applied in practice.