High-Density 3.3 kW GaN Rectifier for Server Applications Comprising a 130 kHz Totem-Pole PFC and a 500 kHz LLC

Abstract:
In this paper, a complete 3.3 kW full power supply unit (PSU) for server applications and the related design challenges are discussed. The proposed unit can target high power in very small form factor by means of the use of wide-bandgap (WBG) GaN and SiC switches, and features hold-up time extension as per server requirements. The designed unit is capable of 3.3 kW maximum steady state output power at 230 VAC down to 176 VAC input, with 50 VDC output voltage. It fits 72 mm x 40 mm x 192 mm dimensions, total peak efficiency of 97.4 % at 230 VAC input, resulting in a total power density of 96 W / in (exp3). The PSU will also incorporate a baby-boost converter to enable 10 ms hold-up during AC line dropout conditions.