宽禁带功率器件高速短路保护电路的研究

The SiC MOSFET is regarded as an attractive alternative of the conventional Si IGBT for the high power density applications like electric vehicle and aerospace. However, the application issues for SiC MOSFET have not been fully resolved yet, which is one of the factors hindering its wide usage. The short-circuit fault is one of the most critical failure mechanisms in the power converters. Due to the weaker short-circuit withstanding capacity and higher surge current of SiC MOSFET, it brings in a new challenge in the short-circuit protection circuit design. As a novel detection strategy, the gate charge detection has attracted more and more attentions due to its high speed and easy-to-integration with the gate driver. However, the early works were mainly focused on the Si IGBT, only few works were conducted on the SiC MOSFET. Consequently, this work investigates the short-circuit protection circuit design based on the gate charge detection for the SiC MOSFET under high-speed switching. Firstly, the impact of parasitic parameters on the switching transitions are investigated by the small-signal model analysis. Secondly, a protection circuit based on the commercial driver IC is studied as a comparative design. Finally, the protection circuit design based on the gate charge detection as well as its mechanism are investigated, thus to conclude its advantages and feasibility of integration.

SiC MOSFET在电动汽车、航天等要求高功率密度的应用中替代传统Si IGBT有着非常吸引的前景，但其中一系列应用难点仍然未能得到很好的解决，成为了限制广泛应用的因素之一。短路失效是电力电子系统中最为重要的失效机制。考虑到SiC MOSFET相比Si IGBT短路承受时间更短，并且短路电流更大，其短路保护设计更具有挑战性。而门极电荷检测作为一种新型的检测手段，由于其高速，易于与门极驱动集成的特点得到了越来越多的关注。但早期的研究工作主要对象为Si IGBT，关于SiC MOSFET短路保护电路的工作少有报道。因此，本项目研究高速开关下SiC MOSFET基于门极电荷检测的短路保护电路设计。首先，通过小信号等效模型分析寄生参数对开关瞬态的干扰。然后，作为对比设计方案，研究基于商用驱动芯片的保护电路设计。最后，重点突破门极电荷检测短路保护电路设计，明确电荷检测机理，探索其优势与集成可行性。

SiC MOSFET在电动汽车、航天等要求高功率密度的应用中替代传统Si IGBT有着非常吸引的前景，但短路等可靠性疑点成为限制其在工业界广泛应用的因素之一。考虑到SiC MOSFET相比Si IGBT短路承受时间更短，短路电流更大，并且开关速度更快，要求SiC MOSFET的短路保护电路需要具有更快的响应速度，并且不受寄生效应的干扰。因此，本项目从寄生参数对SiC MOSFET高速开关机理的研究出发，提出了一种抑制开关振铃的策略从而降低其对周边电路与系统的电磁干扰。然后，进一步对比了Si IGBT与SiC MOSFET 的开关与短路特性，并提出了一种简易的改进型去饱和检测电路，实现了910 ns的保护速度。最后，基于门极电荷检测电路，并结合数字控制的策略，所得到的短路保护电路可实现600 ns的保护速度。并且该电路还可同时实现对SiC MOSFET的在线健康状态监测。