稳态电压加速应力下晶闸管特征参数退化规律及失效机理分析

Degradation Law and Failure Mechanism Analyses of Thyristor Characteristic Parameters Under Steady State Voltage

晶闸管是换流阀的核心元件,在服役期间承受长期的电应力作用,一旦器件特性退化引发系统性失效,会严重影响换流阀甚至整个直流输电工程的安全运行。为研究晶闸管在稳态电压应力下的退化特性,该文设计并搭建了稳态电压应力加速实验平台及晶闸管特征参数测量系统。稳态电压加速应力为1.06倍晶闸管额定电压,选取反向恢复特性、通态电压、漏电流和门极触发特性为退化特征参数。结果表明:电压应力对晶闸管反向恢复特性、通态电压、正向阻断能力和门极触发特性没有显著的影响,但会导致晶闸管反向漏电流的增加和反向漏电流测量不稳定现象的发生,且认为这种测量不稳定现象是其退化和失效的先兆表征。通过对失效器件的失效分析,获得了电压应力下晶闸管的主要失效模式为反向耐压降低,并发现器件的退化和失效主要发生在芯片表面造型处。

The thyristor the core component of the converter valve,bears long-term electrical stresses during its service period.Once there is a characteristic degradation,the safe operation of the converter valve and even the entire DC transmission project will be seriously affected.In order to study the degradation characteristics of thyristors under the steady-state voltage,this paper designs and builds a steady-state voltage accelerated stress experiment platform and a characteristic parameter measurement system for the thyristors.The steady-state voltage acceleration stress is set as 1.06 times the rated voltage of the thyristor,and the reverse recovery characteristics,the on-state voltage,the leakage current and the gate trigger characteristics are selected as the degraded characteristic parameters.Degradation data shows that the voltage stress has no significant effect on the reverse recovery characteristics,the on-state voltage,the forward blocking ability and the gate trigger characteristics of the thyristor.However,it will cause the increase of the reverse leakage current of the thyristor and the instability of the reverse leakage current measurement,which is considered to be a precursor to the degradation and failure of the thyristor.Through the failure analysis of the failed devices,the main failure mode of the thyristor under voltage stress is the reverse withstand voltage reduction,and it is found that the degradation and failure of the device mainly occur on the surface of the chip.