Influence of Temperature and Frequency on Electric Field Reduction Method via a Nonlinear Field Dependent Conductivity Layer Combined with Protruding Substrate for Power Electronics Modules

TL;DR

This paper develops a FEM-based model to evaluate how temperature and frequency affect an electric field reduction method in power electronics modules that combines nonlinear conductivity layers with protruding substrates.

Contribution

It introduces a finite element model to analyze the impact of temperature and frequency on a novel electric field mitigation technique in power modules.

Findings

Temperature and frequency significantly influence electric field distribution.

The proposed method remains effective up to 250°C and 1 MHz.

Model results guide optimal design parameters for high-temperature, high-frequency applications.

Abstract

As shown in our previous studies, geometrical field grading techniques such as stacked and protruding substrate designs cannot well mitigate high electric stress issue within power electronics modules. However, it was shown that a combination of protruding substrate design and applying a nonlinear field-dependent conductivity layer could address the issue. Electric field (E) simulations were carried out according to IEC 61287-1 for the partial discharge test measurement step, where a 50/60 Hz AC voltage was applied. However, dielectrics, including ceramic substrate and silicone gel, in power devices undergo high temperatures up to a few hundred degrees and frequencies up to 1 MHz. Thus, E values obtained with electrical parameters of the mentioned dielectrics for room temperature and under 50/60 Hz may not be valid for high temperatures and frequencies mentioned above. In this paper, we address this technical gap through developing a finite element method (FEM) E calculation model developed in COMSOL Multiphysics where E calculations are carried out for different temperatures up to 250 C and frequencies up to 1 MHz. Using the model, the influence of temperature and frequency on our proposed electric field mitigation technique mentioned above is evaluated.