The conduction resistance of a SiC MOSFET is an indirect indicator of its junction temperature, provided that the R_ON versus temperature and current characteristic of the device is preliminarily mapped. Such R_ON map is normally obtained using dedicated laboratory equipment such as a curve tracer. In this work, the R_ON maps of the power devices of a 3-phase Voltage Supply Inverter are obtained via self-calibration test with the converter already connected to the target synchronous reluctance motor. The proposed procedure consists of a preliminary self-heating stage followed by R_ON mapping through current pulses along the zero-torque directions of the dq rotor reference frame. A polynomial model is then used to extrapolate the R_ON characteristic out of the measurement domain.
