Design of 20 kW Full-SiC, Three-level Three-Phase Uninterruptible Power Supply

In this paper, design and implementation for high efficiency 20 kW, 480 V_ac' 800 V_dcfull-SiC based UPS has been presented. Loss of commercial 2-level and 3-level modules are compared based on the datasheet values. Based on the result, a 3-level NPC topology has been selected which showed higher efficiency for high switching frequency range compared to 2-level case. A double-pulse test has been conducted to extract switching-loss with a designed gate driver. A lumped parameter thermal circuit simulation has been conducted to simulate the rise of junction temperature and conduction loss. A LCL filter has been designed to meet a THD requirement while the loss and power-density are optimized. The operation and efficiency has been verified by a prototype UPS. For double-conversion efficiency, 97.6% at full load can be achieved which is equivalent to 98.8 % per single AC-DC conversion.