Online Condition Monitoring of Bond Wire Degradation in Inverter Operation

This paper presents a condition monitoring system for the online detection of the degradation of power switches in medium power inverter topologies. The monitoring, suitable for MOSFET and IGBTs, is based on the measurement of both on-state voltage of the semiconductor and the voltage drop in the bond wires. Through these measurements, the main failure mechanisms, been these the degradation of the solder joints and the bond wire connections, can be anticipated. The proposed system has been implemented in a setup and tests have been performed in static conditions and as an inverter, with a switching frequency up to 5 kHz. Moreover, this paper proposes an alternative routine appropriate for those applications in which a higher switching frequency is required. This routine has been validated with the DUT switching at 50 kHz. In all the circumstances, the prototype proved its efficiency to measure accurately and its capability to detect the bond wire degradation.