碳化硅器件的短路保护:设计准则和电路

SiC MOSFET Short Circuit Protection:Design Principles and Circuit

为了保障碳化硅(silicon carbide,SiC)在发生短路故障时可安全可靠的关断,需在掌握其短路特性基本规律的前提下,针对SiC短路耐受时间较短、短路下器件漏源极电压拐点不明显等特征,展开去饱和保护电路(desaturation fault protection,DESAT)电路中关键参数的研究,并制定其工程化设计的参考标准。在此基础上,文中进一步提出基于氮化镓(gallium nitride,GaN)的高速、低传输延时的DESAT短路保护电路,短路保护电路的驱动动作延时仅为常规基于硅器件DESAT电路的23.2%。所提出的氮化镓DESAT电路为SiC MOSFET短路保护电路的更优越的实现方案。

Short circuit protection is critical to ensure that Silicon Carbide(SiC)MOSFET can be safely and reliably turned off under short-circuit fault.Due to SiC MOSFET's short withstand time and no-obvious inflection point of device’s drain-source voltage under short-circuit fault,conventional desaturation fault protection(DESAT)circuits for Si IGBT are not applicable for SiC MOSFETs.Therefore,this paper focused on the key parameters for DESAT circuits and developed an appropriate design principles for SiC MOSFETs.This paper further proposed a high-speed,low transmission delay DESAT short circuit protection circuit based on GaN devices.The driving action delay is demonstrated to be 23.2%of the conventional DESAT circuit based on Si devices.Hence,the proposed GaN DESAT circuit is a more superior solution for the SiC MOSFET short circuit protection with lower loss,faster and more compact.