FEM simulation based study of electric field reduction by linear and nonlinear resistive solution for HV power module under switching operation

Abstract

The development of wide band gap semiconductor devices, in answer to the increase in the voltage level and the power density of power electronics converters, requires the development of new solutions for their electrical insulation systems, especially for the electric field reduction in power modules. The introduction of a resistive material within the encapsulation system, either as an added surface layer, or using the encapsulating bulk material, is one solution reported. In most cases, the related studies have been made by observing the steady state of an excitation in time domain. However, the isolation system in power modules is exposed to Pulsed Width Modulation (PWM) signals with a high switching speed. In this study, we investigate the resistive solution in the transient regime with a high slew rate voltage pulse excitation, close to realistic switching signals endured by the new semiconductor power devices (exhibiting dV/dt up to 100 kV/µs).