Asymmetrically Driven HB-LLC Resonant Converter Integrated in Low-Power IoT Devices

This paper introduces a generalized time-domain analysis framework for asymmetrically driven half-bridge LLC (HB-LLC) resonant converters. It allows accurate gain derivation and monotonicity attributes characterization for both CCM and DCM, i.e. for high- and low-Q operating conditions with any arbitrary duty-cycle ratio. The analysis is carried out without using First-Harmonic Approximation (FHA) and takes into consideration the resonant capacitor ripple, thus truthfully obtaining the converter's load-dependent gain curves. The analysis framework is experimentally verified on a compact converter operating in the MHz range for low-power IoT applications, demonstrating the non-monotonicity attributes of asymmetrically driven HB-LLC resonant converter and validating the accuracy of its gain derivation procedure for various operating conditions.