Characterization in ZVS Mode of SiC MOSFET Modules for MVDC Applications

In order to improve the energy efficiency of the railway traction power supply, a DC voltage of 9 kV has recently been proposed. Beyond train power supply, this new power system will allow to connect several sources and/or loads (AC power grid, energy storage, wind farm, solar panels, etc.). This new railway “smart grid” will require insulated DC-DC converters operating in a medium frequency range (from 10 to 20 kHz) to reduce the size of the passive components (mainly the transformer). In the voltage and power ranges targeted, this is now possible thanks to the arrival on the market of power modules based on SiC MOSFETs. Therefore, this paper focuses on the operation in ZVS mode of two power modules (1.7 kV / 1100 A and 3.3 kV / 750 A). The first part of the paper is devoted to the design of a driver for Zero Voltage Switching. In a second part, a test bench is presented. It allows to measure the switching energies in this operating mode. Finally, from these results, it is then possible to determine the efficiency of resonant DC/DC converters, which can be used in the MVDC power system.