Evaluation of selected diagnostic variables for the purpose of assessing the ageing effects in high-power IGBTs

A method is presented and discussed whereby to evaluate two basic diagnostic variables that can be used in the assessment of the health of high-power IGBT packs. The proposed approach attempts to adapt a laboratory-grade method known from the literature for the use on board electric traction vehicles. The diagnostic variables in question are the junction-to-case thermal resistance and the collector-emitter saturation voltage. These variables can be used in the assessment of the depth of IGBT structure delamination and wire-bond lift-off. The proposed approach has been partially validated by experiment.