Switching SiC Devices Faster and More Efficient Using a DBC Mounted Terminal Decoupling Si-RC Element

Abstract

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.

Analysis of the Zero Overvoltage Switching Phenomenon

“…To avoid this, a Si-RC element compared to a ceramic capacitors can be implemented. In [12] a Si-RC device is placed physically close to the transistors, in order to reduce the effective parasitic inductance of the commutation cell as well as damping voltage oscillations.…”