Analysis of Light Load Fast Response LCC Resonant Converter Based on Simplified State Trajectory

Rapid dynamic response has been a crucial performance metric in the control of LCC resonant converter. In this article, the simplified state trajectory of the LCC resonant converter under light load and heavy load are examined. By analyzing the geometric characteristics of the steady-state trajectories and the charge transfer properties of the resonant tank, deriving the coordinates of various points and the state trajectory equations under various loads becomes a straightforward task. The optimal trajectories under light load are designed, and the time required for trajectory switching is also calculated through the corresponding trajectory equations. Through experimental validation, it has been demonstrated that state variables of resonant tank can smoothly transition to the next steady trajectory within one cycle under light load. The voltage overshoot is reduced by more than 80%, and the settling time has been shortened by 75%. Ultimately, fast dynamic response under light load is achieved.