Online Junction Temperature Monitoring of Power Semiconductor Devices Based on a Wheatstone Bridge
Niklas Fritz, Maximilian Friedel, Rik W. De Doncker, Timothy A. Polom, 2021 IEEE Energy Conversion Congress and Exposition (ECCE), 16 November 2021.
Monitoring the junction temperature of power semi-conductor devices is a requirement for degradation monitoring and predictive maintenance of power-electronic converters and usually achieved by online measurement of a temperature-sensitive electrical parameter (TSEP). The on-state voltage of a MOSFET or an IGBT is such a TSEP; however, a monitoring circuit has to accurately measure the small on-state voltage while withstanding the high off-state voltage across the device. This paper proposes a monitoring circuit for the on-state voltage based on the topology of a Wheatstone bridge. Compared to other approaches in the literature, the proposed circuit promises higher precision and good dynamic response properties. For validation, a test PCB is designed and experiments are carried out. In the experiments, it is shown that the proposed circuit has excellent properties in terms of off-state voltage limitation, on-state voltage resolution, and bandwidth.