Stepwise Transitions Control for Reconfigurable LLC Resonant Converters with Multiple Modes

The challenge of balancing the wide voltage range and frequency range of an LLC resonant converter has been addressed through the development of hybrid control methods and topologies with multiple operating modes. To effectively mitigate voltage and current overshoot or dips caused by mode switching, a transition control strategy is deemed indispensable. In this paper, a stepwise transition control strategy is proposed. Based on a reconfigurable LLC resonant converter with three operating modes, which requires the manipulation of two variables, namely duty cycle and frequency, smooth switching between modes can be achieved. An experimental prototype with a 300W 400V input is constructed, and its experimental waveforms verify the feasibility and effectiveness of the transition control strategy.