Dynamic AC Line Frequency Response Method for LUT-Based Variable On-Time Control in 360–800 Hz CRM Boost PFC Converter

To improve the input current total harmonic distortion (THD), the look-up table (LUT) method is used in the 360-800 Hz critical conduction mode (CRM) boost power factor correction (PFC) converter. When the ac line frequency changes drastically and suddenly, the zero-crossing detection method needs the half ac line period to follow the sudden frequency jump, causing a mismatching between the LUT and the ac line frequency. This mismatching in the time domain leads to a large current spike in the input current and even destruction in the PFC converter under some severe conditions. In this letter, a dynamic ac line frequency response method is proposed to eliminate this mismatching. The proposed method only needs to sample the input voltage, leading to a good performance in following the sudden frequency jump in a wide input voltage range. The effectiveness of the proposed method is verified with a 160 W GaN-based CRM boost PFC converter.