FPGA Controller Design for High Frequency LLC Resonant Converters

Abstract

Conventional digital controllers have a limited switching frequency resolution and computational speed. It results in 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. In this paper, a field programmable gate array (FPGA) controller design for an LLC resonant converter is developed 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 improvements have been verified with circuit simulations and signal-level tests using a hardware-in-the-loop (HIL) test system.