CPC H02M 3/33573 (2021.05) [H02M 1/0009 (2021.05); H02M 1/0035 (2021.05); H02M 1/08 (2013.01); H02M 3/33592 (2013.01)] | 16 Claims |
1. An LLC resonant converter configured to convert an input voltage into an output voltage, the LLC resonant converter comprising:
a transformer,
a primary-side circuit coupled to a primary-side winding of the transformer, the primary-side circuit comprising:
a first bridge arm comprising a first switch and a second switch connected to the first switch in series, and configured to receive the input voltage, and
a second bridge arm connected to the first bridge arm in parallel, and comprising a third switch and a fourth switch connected to the third switch in series, and
a control unit configured to provide a first control signal to control the first switch, and provide a fourth control signal to control the fourth switch,
wherein the control unit is configured to adjust a switching frequency of the first control signal and the fourth control signal according to the output voltage; when the switching frequency increases to a frequency threshold value, the control unit controls the switching frequency to be fixed at the frequency threshold value, and controls the first control signal and the fourth control signal having a variable phase difference, and
wherein when the switching frequency is equal to the frequency threshold value, the control unit controls the phase difference not to excess a phase shift threshold value.
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