Energy efficiency of a SiC MOSFET propulsion inverter accounting for the MOSFET's reverse conduction and the blanking time

MOSFET devices have a body diode that allows reverse conduction, additionally, when a negative drain-source voltage is present, the MOSFET channel conduction can also be controlled by applying a gate-source voltage above the threshold voltage level. In a three phase inverter this results in parallel conduction of the diode and MOSFET when voltage and current differ in sign. This paper analyzes the beneficial effect of parallel operation of the two devices, taking into account the blanking time, on the conduction losses and total efficiency for a three phase SiC MOSFET inverter for traction application in electrified vehicles. The losses of the inverter are derived and presented as an analytical expression and compared with a numerical implementation showing a perfect match of the two. The total losses and efficiency of the inverter are derived and analyzed with and without reverse conduction for different operating points.

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