2.5KV-30A inductively loaded half-bridge inverter switching using 4H-SiC MPS free-wheeling diodes

In this work, 4H-SiC MPS diodes were designed, fabricated and tested. The MPS diodes were fabricated based on a 30μm, n=2×10¹⁵cm ^-3 doped drift layer. The diodes were designed with a multi-step junction termination extension (MJTE) to improve the blocking voltage, resulting in MPS diodes blocking over 4kV. DC I-V testing of the packaged MPS diode showed a forward voltage drop V_F=3.2V at a forward current I _F=27A. A half-bridge inverter with a bus voltage up to 2.5kV and a large load inductance of 1mH was used to characterize the MPS diode switching performance. The large inductance load was used to simulate the load of a high power AC induction motor. Switching measurements up to a current of 30A showed a substantial reduction in diode turn-off energy loss, compared to state-of-the-art ultra fast 40ns, Si diode: as high as 51% energy loss reduction at room temperature (RT). Most energy loss reduction, however, comes from the saving in the corresponding Si IGBT switch, which sees a reduction of as high as 51% at room temperature. Past reports on half-bridge inverter testing were largely done at bus voltage of a few hundred volts. This is the first half-bridge, highly inductively loaded inverter test at bus voltage of 2.5kV.