Large power modules include several parallel mounted chips per switch to raise active area and current. By the electro-mechanical connection interface, the resulting large parasitic inductance is a huge problem especially for very fast switching SiC devices. This challenge is handled by many approaches, but these recent developments require additional development effort along all aspects of the power module, e.g. smart DBC layout, low inductive top side metallization, special terminal designs or additional pins. In this paper we demonstrate an approach to enable excellent switching performance with con-ventional power module technologies: By using a recently developed monolithic silicon RC (Si-RC) element to decouple the bus bar, this problem can be solved in a very efficient way. The Si-RC element is assembled directly adjacent to the power switches on the DBC. This allows a significant reduction of the SiC chip area by minimizing the power losses caused by the switching transients from the parasitic DC-link and module inductances.

In common understanding, the fast switching speed of wide-bandgap devices leads to high overvoltage and oscillations, if no countermeasures are taken. Those countermeasures were introduced in the past, and include methods such as build-in gate resistors or low-inductive power modules. There is, however, a physical limit for reducing the parasitic inductance of the commutation cell. This is one of the reasons why the full potential of wide-bandgap devices cannot be entirely utilized. In contrast, the Zero Overvoltage Switching (ZOS) phenomenon can be used to theoretically unleash unlimited switching speed with no switching losses and voltage overshoots. This method triggers the inherent parasitic oscillating elements of a commutation cell to perform an ideal current commutation. This article investigates the physical effects and usage of this technology in real-world applications. The model of an ideal commutation cell is adapted to reality by introducing damping factors as well as the nonlinear behaviour of the parasitic capacitances. An extended ZOS area is presented, including the parasitic capacitances of two wide-bandgap devices. It allows today's silicon carbide power modules to make use of the ZOS technology and perform at different power levels. Measurements with a commercially available power module were taken to verify the theoretical analysis and the derived equations.