Design of three-level flying-capacitor commutation cells with four paralleled 650 V/60 A GaN HEMTs

This paper presents two improved solutions (Vertical and Horizontal commutation cells according to cell disposition in the PCB) for three-level flying capacitor (FC) topologies with four 650 V/ 60 A (25 mΩ) GS66516T GaN (Gallium Nitride) HEMTs (High Electron Mobility Transistors) in parallel per switch intended to be used in a 540 V / 70 kVA power drive system. Both solutions were built and experimentally tested, as a buck converter, regarding switching speed (15.14 kV / µs max) and overvoltage (6 % max) for different current levels (7 A to 53 A).