Coordinated Online Junction Temperature Estimation of MOSFETs and Antiparallel Diodes in Three-Phase SiC Inverters

This article builds on previous work on SiC MOSFETs temperature estimation extending what was previously proposed to the temperature estimate of antiparallel diodes on board of a real-world power converter. The calibration test has been improved to map the antiparallel diodes, and their junction temperature is estimated during PWM under load. As pointed out in Section V-E, the estimated junction temperature is representative of the average temperature of the die surface and does not take into account the presence of hotspots. Although the diodes temperatures are typically overlooked in MOSFET converters for being considered not critical, this might not always be the case, especially in those converters where antiparallel diodes are not designed for continuous operation (e.g., failure condition of an inverter connected to a rotating machine with all MOSFETs commanded open and the inverter operating as a diode bridge rectifier). Despite that, the proposed methodology can provide valuable information enabling to fully exploit the SOA of the components without virtually any risk of thermal failure. The proposed advanced capability of diodes monitoring comes at zero hardware cost and little software complication with respect to the setup used for SiC MOSFET temperature tracking.