Real-Time Degradation Level Assessment of IGBT Gate Oxide Layer Using Turn-Off Delay Time
Mojtaba Jazayeri, Sadegh Mohsenzade, Javad Naghibi, Kamyar Mehran
Abstract
Condition monitoring (CM) of the components with highest probability of failure in converter circuits can significantly contribute to having a long-term reliable operation. Insulated-gate bipolar transistors (IGBTs) are considered as one of the most fragile parts with the highest failure rates in many power electronics applications. This article proposes a real-time CM technique for assessing the IGBT gate oxide degradation level. The proposed technique is based on the device turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> delay time interval, which as we discovered, decreases during the device gate oxide degradation (DGOD) process. Therefore, this article proposes a practical fully analogue circuit to capture the device turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> delay time and convert it to a dc voltage as the final output of the CM circuit. The DGOD precursor output can be effectively used to assess the health status of IGBT gate oxide layer during the device real-time operation. Two different types of 600 V/60 A discrete IGBTs from different manufacturers are used in the experimental verification process. In addition, the proposed CM technique is applied to a 500 W boost dc–dc converter to evaluate the applicability of the proposed CM technique to real-world converter operation. The results indicate that the proposed DGOD precursor shows a 50% change when the device experiences full gate oxide degradation.