Performance Evaluation of Different Freewheeling Device Implementations for SiC MOSFETs with Kelvin Source Connections

This paper discusses the optimization of freewheeling device implementation for SiC MOSFET’s with kelvin source connections. Kelvin contacts permit improved switching speed by reducing error voltages resulting from unwanted current effects. However, Kelvin contacts can also permit the switching transient reverse recovery (RR) phenomenon to be more easily observed. The behavior of the body diode of SiC MOSFETs with Kelvin source connections will be different to that of traditional packages without Kelvin source connections. This paper aims to test whether the body diode of a SiC MOSFET is a limiting factor for high speed switching of MOSFET’s with Kelvin source connections. Two characterization platforms were developed to measure the pulse switching energy and continuous switching efficiency of a ‘phase leg’ SiC MOSFET’s stage with different freewheeling device implementation including SiC MOSFET body diode with and without anti-parallel Schottky Barrier Diodes (SBD). The switching energy and converter efficiency results are presented to quantify the benefits of adding antiparallel SBD on loss reduction and EMI noise mitigation for SiC MOSFETs with Kelvin source.