Improving Power Converter Reliability: Online Monitoring of High-Power IGBT Modules

The real-time junction temperature monitoring of a high-power insulated-gate bipolar transistor (IGBT) module is important to increase the overall reliability of power converters for industrial applications. This article proposes a new method to measure the on-state collector-emitter voltage of a high-power IGBT module during converter operation, which may play a vital role in improving the reliability of the power converters. The measured voltage is used to estimate the module average junction temperature of the high and low-voltage side of a half-bridge IGBT separately in every fundamental cycle of the current by calibrating them at load current. The measurement is very accurate and also measures the voltage at the middle of a pulse-width modulation (PWM) switching. A major objective is that this method is designed to be implemented in real applications. The performance of this technique is measured in a wind power converter at a low fundamental frequency. To illustrate more, the test method as well as the performance of the measurement circuit are also presented. This measurement is also useful to indicate failure mechanisms such as bond wire lift-off and solder layer degradation. The measurements of and rise in the junction temperature after five million cycles of normal operation of the converter are also presented.