Digital-Based Interleaving Control for GaN-Based MHz CRM Totem-Pole PFC

Abstract

This paper presents a comparison between the performances of different interleaving control methods for gallium nitride devices-based MHz critical conduction mode (CRM) totem-pole power factor correction (PFC) circuit. Both closed-loop interleaving and open-loop interleaving are good for the 70-kHz CRM PFC; but for a MHz frequency CRM PFC with microcontroller (MCU) implementation, the open-loop interleaving outperforms the closed-loop interleaving with only a small and nonamplified phase error. After software optimization, the phase error of the open-loop interleaving is smaller than 3° at 1 MHz, when the control is implemented by a 60-MHz low-cost MCU. Significant ripple cancellation effect and differential-mode (DM) filter size reduction are achieved with good interleaving. For a 1.2-kW MHz totem-pole PFC, the DM filter size is reduced to one quarter when compared with the counterpart of a 100-kHz PFC. Last but not least, the stability of the open-loop interleaving is also analyzed indicating that the MHz CRM totem-pole PFC with voltage-mode control, open-loop interleaving, and turn-on instant synchronization can maintain critical mode operation with better stability compared with the 70-kHz CRM PFC.