High-speed medium voltage (MV) drive applications enabled by series connection of 1.7 kV SiC MOSFET devices

The medium voltage (MV) high-speed drives are required for traction, wind energy, marine, aerospace, oil, and gas compressors applications. The MV converter must be able to switch at higher switching frequencies (> 5 kHz) to generate higher fundamental frequency AC input voltages for the motor (≥ 500 Hz) and thereby achieving high speed at the motor output (≥ 15000 rpm). This paper presents the series connection of 1.7 kV SiC MOSFET devices to enable simple two level MV converter for high-speed drive and grid connected applications. Experimental switching characterization of a phase leg (one pole of a three-phase converter) with the series connection of four devices per arm (or eight per leg) has been presented. It also presents the experimental results of a DC-AC half-bridge inverter with four devices in series per arm at 3kV dc bus, at different fundamental frequencies. It also includes the experimental endurance test results of phase-leg (pole) in a DC-DC converter at 100 kW, 3kV dc bus. Furthermore, it also presents the performance evaluation of a 3-phase voltage source inverter (VSI) efficiency using four series connected devices for 3.6 kV dc bus, 2.1 kV AC(L-L), 720 kW output power and its comparison with single 6.5 kV Si IGBT.