A Novel Phase-Mode Controller for Resonant Converters

This work proposes an analog implementation of phase-mode control (PMC) for resonant converters, suitable for integration into a low-cost silicon chip. The PMC method, which is based on controlling the displacement angle (phase shift) between the voltage applied to the resonant tank and the resonant current, has been long overlooked in the industry despite its significant benefits. Control robustness (insensitivity to component tolerance), intrinsic ZVS operation (the control ensures that the resonant current lags the applied square-wave voltage), fast transient response, potential for high-efficiency designs, and system simplification are very well documented in the literature.This work, after describing the proposed phase-mode controller and determining the related control law, discusses the challenges of its integration into a control IC. Although PMC is applicable to any voltage-fed resonant converter, in this work the LLC converter is considered for the large and small-signal analysis as well as for the experiments. The good performance of the proposed controller is demonstrated, and the expected benefits are confirmed.