A 3kW, 500 kHz E-mode GaN HEMT based Soft-switching Totem-pole PFC

Abstract

This paper demonstrates the performance improvement of high frequency based totem-pole power factor correction circuit (PFC) using wide band gap (WBG) devices. Currently, the typical totem-pole PFC using WBG devices tend to operate at frequencies lower than 100 kHz under continuous conduction mode (CCM) and greater than 100 kHz with multi-phase interleaved versions of discontinuous conduction mode (DCM) or critical mode (CRM) converters. Soft-switching topologies employing WBG devices can drive the system at much higher rates under CCM, resulting in an efficient and compact design. A totem-pole PFC circuit with a low-loss, zero voltage transition (ZVT) auxiliary branch has been recently proposed, which provides zero voltage turn-on for the high frequency switches, with zero current switching (ZCS) for the auxiliary branch devices. However, due to resonance between the auxiliary switch capacitances and auxiliary inductor causes large over voltage stress across the auxiliary switches. This limits the use of commercially available GaN devices for this application. In this paper an improved soft-switching totem-pole PFC topology is demonstrated using enhanced-mode (e-mode) GaN HEMTs with the addition of snubber circuits. Also, rigorous studies have been conducted for different snubber configurations to alleviate the overvoltage stress and improve converter efficiency even with the presence of snubber. Comprehensive simulation and experimental results are illustrated for a 3kW, 500 kHz E-mode GaN based hardware prototype, achieving a peak efficiency of 98.68% at 2.86kW.