This work proposes an analog implementation, suitable for integration into a low-cost silicon chip, of phase-mode control for resonant converters, a method based on controlling the displacement angle (phase-shift) between the voltage applied to the resonant tank and the resonant current. This technique, quite overlooked for a long time, brings some important benefits that can be summarized in control robustness (insensitivity to component tolerance), intrinsic ZVS operation (the control constrains the resonant current to lag the applied square-wave voltage), fast transient response, opportunity for high efficiency designs, and simplification of the overall system. This paper focuses on the large and small-signal analysis of the proposed phase-mode controller, also discussing some of the challenges posed by its integration into a control chip. Phase-mode control is applicable to any kind of voltage-fed resonant converter. An LLC half bridge converter is used for the experiments carried out to demonstrate the performance of the proposed phase-mode controller and confirm the expected benefits and results.
