A GaN-Based CRM Totem-Pole PFC Converter with Fast Dynamic Response and Noise Immunity for a Multi-Receiver WPT System

The soft-switching gallium-nitride (GaN) based critical conduction mode (CRM) totem-pole power factor correction (PFC) converter is a good candidate for the front-end rectifier in wireless power transfer (WPT) applications. In multi-receiver MHz WPT systems, the PFC converter is required to have fast dynamic response and noise immunity. In this work, a GaN-based CRM totem-pole PFC converter is designed for a multi-receiver wireless charging power supply. Digital-based variable on-time control is used to achieve the zero voltage switching (ZVS) within the whole line cycle, and a voltage-loop controller with notch filters is designed to improve the transient response. The impact of high-frequency noise on the sensing signals and ZVS control are analyzed, and implementation methods are proposed to mitigate the disturbances. A GaN-based CRM totem-pole PFC that is demonstrated with 98.5% full-load efficiency is built as the first stage in the transmitter of a 100 W 6.78 MHz multi-receiver WPT system. The noise immunity of the CRM PFC is verified by testing the whole WPT system. Experimental results show that the system end-to-end efficiency at full load is 90.16%, and fast dynamic response is achieved during load variation.