一种基于MOV-RC缓冲电路的中压直流固态断路器过电压抑制方法研究

Research on overvoltage suppression method of medium voltage DC solid state circuit breaker based on MOV-RC snubber circuit

本文针对常通型碳化硅(SiC)结型场效应晶体管(JFET)的中压直流固态断路器(SSCB)缓冲电路进行了优化设计。首先,分析中压SiC SSCB主开关器件内部寄生电感、外部印制电路板电感和功率回路电感等因素对开关过程的影响作用,阐述了电阻电容二极管(RCD)型、金属氧化物变阻器(MOV)型、RCD+MOV混合型三类经典缓冲电路应用于SiC SSCB时的工作原理,并对其性能进行了评估。基于对三类经典缓冲电路特点的全面分析,为SiC SSCB设计了一种基于金属氧化物变阻器-电阻-电容MOV-RC结构的新型缓冲电路拓扑,基于该电路的工作原理提供了适配的参数调制方法。最后,搭建了以三个1200 V/38 A常通型SiC JFET器件串联组成的1.5 kV/38 A SSCB实验样机,验证了本文所提设计方案的有效性。仿真及实验结果表明该缓冲电路不仅有效抑制了SiC SSCB故障隔离期间的过电压,还具有较快的故障清除时间和低成本的优势。

This article optimizes the design of the medium-voltage DC Solid State Circuit Breaker(SSCB)snubber circuit based on normally-on Silicon Carbide(SiC)junction field-effect transistor(JFET).First,considering the factors such as parasitic inductance inside the medium-voltage SiC SSCB main switch SiC JFET device,printed circuit board inductance,and power circuit inductance,RCD-type,MOV-type,and RCD+MOV hybrid-type three typical snubber circuits applied to SiC SSCB are analyzed for their operation principles and performance evaluation.Based on this,a MOV-RC snubber circuit design suitable for SiC SSCB is proposed,and the operation principle and parameter design method of the circuit are described in detail.Finally,a 1.5 kV/38 A SSCB experimental prototype based on three 1200 V/38 A normally-on SiC JFET devices in series was built to verify the effectiveness of the snubber circuit design scheme.The simulation and experimental results show that the snubber circuit design scheme not only effectively suppresses overvoltage during SiC SSCB fault isolation,but also has the advantages of fast fault clearance time and low cost.