Self-Calibrated Digital Current Emulation for High-Frequency Hysteretic Current-Mode Control in GaN PFC Converters

This work presents a digital emulation technique that reproduces the switching-frequency behaviour of the inductor current in a power converter, enabling high-frequency (HF) cycle-by-cycle hysteretic current-mode control for applications with limited current-sensing opportunities. The proposed technique leverages lower-bandwidth current sensors to opportunistically self-calibrate the emulator, alleviating its dependence on preset system parameters. Removing the need for high-bandwidth sensors enables low-inductance power loops, critical for maximizing performance in HF converters. The design is demonstrated in a 240-Vrms-to-450-V all-GaN totem-pole PFC converter operating at 4kW.