FPGA Controller Design for High-Frequency LLC Resonant Converters

Abstract

Conventional digital controllers have limited switching-frequency resolution and computational speed. This results in a large output voltage ripple and poor dynamic performance with a low control bandwidth in high switching frequency resonant converters using an inductor-inductor-capacitor (LLC)-type resonant tank. This paper proposed a controller design based on a field programmable gate array (FPGA) for an LLC resonant converter to improve the switching-frequency resolution and dynamic performance. The improved performance is analyzed using theoretical methods compared with that of a general-purpose digital signal processor (DSP). The performance improvement is verified through circuit simulations and signal-level tests using a hardware-in-the-loop (HIL) test system.