A Transient Response Control Strategy with Power Compensation for GaN-based Buck-Boost LLC Converters

Buck-boost LLC converter (BBLLC) can maintain both high efficiency and wide input voltage range, simultaneously. However, the dynamic performance of BBLLC degrades due to the introducing of an additional stage. To solve this problem, an improved transient response control based on power compensation for BBLLC is proposed. This strategy aims to compensates the lack or excess energy in the output capacitor during load switching. The digital implementation of energy calculation and regulation is also discussed. Compared with the conventional control strategy, the energy lost in the capacitor is calculated by output voltage deviation instead of the capacitor current to avoid the sampling problem. The proposed strategy can be applied to the high frequency converter with low-cost microcontroller (MCU). Finally, experimental results are demonstrated on a 1MHz BBLLC converter with a 72MHz MCU.