Adaptive Tuning Method for ZVS Control in GaN-based MHz CRM Totem-Pole PFC Rectifier

This paper presents an adaptive tuning method to achieve zero-voltage-switching (ZVS) control for MHz Totem-Pole power factor correction (PFC) rectifier operated in critical conduction mode (CRM). The body diode conduction status of the active switch and the synchronous rectifier (SR) switch in the respective half line-cycle is detected and used as ZVS detection signals. According to the detection signals, the synchronous rectifier (SR) turn-off moment and the dead-time period is tuned adaptively on-line to help achieve ZVS of both of the active switch and the SR switch. The proposed adaptive tuning method is easy to be implemented by digital control and does not require massive micro-controller (MCU) calculation resources in full AC line operation. Moreover, it is insensitive to parameter tolerance and signal delays. A GaN-based Totem-Pole PFC prototype is built to demonstrate the adaptive tuning method for ZVS control with efficiency measured 98.5% at 300 W.