Stability Analysis Based on a Virtual Twin of SiC Power MOSFET Module

This paper presents a modeling methodology for simulating dynamic behavior of a multichip power module. A broadband electromagnetic model of a commercial-type power module mounted on a printed circuit board populated with decoupling capacitors, gate drivers and a load inductor, is extracted from the hardware and used in both time and frequency domain simulations to quantitatively evaluate the dynamic performance of SiC power MOSFET dies placed in the module. Furthermore, a new stability analysis approach is developed to assess the switching of the SiC power MOSFETs in the frequency domain. Differently to the state-of-the-art approaches based on an analytical derivation of a system transfer function using a simplified R-L equivalent circuit of module layout parasitics, the proposed approach is based on a numerical extraction of a time-varying system transfer function and a subsequent calculation of all unstable poles in each time point. The developed modeling approach enables an optimization of a module layout design, a calculation of required internal lumped gate resistors, as well as a selection of SiC power MOSFETs for placing in the module, with the aim of suppressing internal gate-to-gate oscillations during switching transients. A feasibility of such a virtual twin of a power module is demonstrated for an actual half-bridge module with 8 SiC power MOSFET dies in parallel per topological switch.