Switching Frequency Prediction Control for FB/HB Morphed LLC DC-DC Converter With Online-Offline Balance

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> dc–dc converters are extensively utilized, and numerous methods exist to expand their voltage gain range. The full-bridge (FB)/ half-bridge (HB) morphed topology is a straightforward and effective approach; nonetheless, the precise prediction of switching frequency has been a tough issue. Inadequate feed-forward of the switching frequency can lead to voltage and current overshoots, potentially damaging the converter. This article introduces an online frequency prediction method grounded in state plane analysis and one-circuit analysis, which effectively reduces the dimensionality of the lookup table while significantly minimizing its overall volume. Experimental results are demonstrated on a 2 kW <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter to verify the effectiveness of the analysis.