Semiconductor Temperature and Condition Monitoring Using Gate-Driver-Integrated Inverter Output Voltage Measurement

Bond-wire liftoff caused by mechanical stress due to thermal cycling is one of the major failures in power electronic systems. Condition monitoring concepts which allow prediction of these failures are often based on voltage-drop detection and thermal monitoring. However, solutions to determine the junction temperature and semiconductor voltage drop during operation often require additional effort and lead to increased cost. In this article, a direct semiconductor temperature detection method is proposed which is based on instantaneous semiconductor voltage-drop monitoring. A MOSFET inverter system, equipped with a digital integration-based instantaneous output voltage measuring circuit, is extended by software to enable instantaneous semiconductor voltage-drop detection. Experimental results demonstrate that the proposed method is feasible for online temperature measurement and detection of increased resistance due to bond-wire faults. The voltage measurement resolution is sufficient for dynamic temperature monitoring, including fundamental frequency temperature cycles at very low frequency.