A High Accuracy and Low-Cost Fatigue Life Evaluation Method for IGBTs Based on Variable-Parameter Power Cycling

Fatigue life of insulated gate bipolar transistor modules (IGBTs) is critical to the reliable application during their long-term servicing. At present, time-consuming and costly power cycling tests are commonly used to obtain the fatigue life model of power electronics devices. In this article, a lower cost and higher efficiency method for the evaluation on the fatigue life of IGBTs was proposed based on variable-parameter power cycling. First, theoretical feasibility of the proposed method was discussed based on fatigue theory. Then, details concerning on the proposed method were described combining with the power cycling data obtained from electro-thermal coupling simulations. Finally, power cycling under both constant and variable parameter was carried out to IGBT modules for experimental verifications. Results dedicate that the fitted fatigue life deduced from the degradation curve of electro-thermal characteristics of IGBTs under variable-parameter power cycling was well consistent with that directly measured from constant-parameter power cycling. It results in an order of magnitude increase in test efficiency and an order of magnitude decrease in costs, which brings huge economic benefit and high efficiency to the fatigue life evaluation of IGBTs.