A Novel SiC Device Modeling With Power Stage and Gate Driver Decoupling

Abstract

Miller capacitor (Cgd) and common source inductor (Lscom) are two major feedback parameters across gate driver loop and power loop for power devices. Silicon Carbide (SiC) power transistors have fast switching speed but are more inclined to be affected by parasitics, such as overshoots, oscillations and cross-talk. To ensure a reliable and efficient SiC switching, the impacts of miller capacitor and common source inductor need to be identified and quantified. Since these two parameters are coupled between two loops, a comprehensive analytical analysis is quite complicated and requires massive computation. Therefore, a novel SiC device modeling based upon Cgd and Lscom decoupling is proposed. By extracted the equivalent model for Cgd and Lscom at different switching intervals, gate driver loop and main power loop can be fully decoupled. By doing so, the designs and optimizations for the two loops will be more straightforward and precise. With the proposed decoupling modeling approach, the decoupled equivalent circuit is verified to have descent accuracy in predicting the actual SiC switching transients.