On-line Health Monitoring of Wire-Bonded IGBT Power Modules using On-State Voltage at Zero-Temperature-Coefficient

Monitoring the health of IGBT power modules is an enabling technology for predictive maintenance. The main failure mechanism of wire-bonded modules is associated with an increase of on-state voltage. This voltage is strongly dependent on the temperature of the die, making the extraction of the degradation difficult in real operating conditions, where the temperature is variable and/or unknown. The solution studied in this paper is to monitor IGBTs at Zero-Temperature-Coefficient (ZTC) current value. This paper proposes and tests a circuit and method to measure on-line the on-state voltage at the ZTC current value. We demonstrate the experimental feasibility to monitor the electrical resistivity increase that is associated with the wire-bond degradation of IGBT power module rated at 150A/1200V driving a sinusoidal current.