Online junction temperature for off-the-shelf power converters

Recent growth of power converter market has been driven largely by the growing demand for an efficient way to convert and distribute energy in the field of electrical vehicles, renewable energy, and aerospace and marine applications. However, failures of power semiconductor devices can reduce the reliability of power converters. It is well-known that the reliability of power semiconductor devices is related to the device junction temperatures. This paper presents an online temperature estimation model for off-the-shelf power converters that estimates the junction temperatures of insulated gate bipolar transistors (IGBTs) in real time. The proposed online model is based on power loss characteristics and thermal-impedance variation for each interval in the operating states of IGBTs. A three-phase power converter consisting of three half-bridge IGBT modules has been built as an experimental test setup to verify the proposed method. To validate the accuracy of the proposed method, the estimated temperatures are compared to the results from temperature measurement by using a thermocouple and an infrared camera.