Designing Power Modules for Degradation Sensing

Abstract

This paper presents a method for designing multi-chip power modules for increased degradation monitoring performance, especially in converter real-time applications. It builds upon prior work which identified variations in three-dimensional transient heat transfer with interface and interconnect state-of-health. This paper contributes a method for a module designer to quantify opportunities and limits in using chip-based temperature sensing to implement electrothermal impedance spectroscopy in an actively switching wide-bandgap module. Challenges intrinsic to modules, such as the presence of multiple, closely packed heat sources, are identified. The paper then examines spatial degrees-of-freedom for placing additional degradation sensing temperature detectors. Experimental measurements of transient thermal frequency response show sensitivity trends that can be exploited to push temperature sensors against their signal-to-noise ratio limits. Overall, the design method relies on circuit topology and modulation details and is directed toward early-stage converter development. To that end, the included harmonic loss modeling step immediately provides a designer with feedback about the feasibility of a degradation sensing concept.