Method and system for balancing multi-phase llc power converter with switch-controlled capacitors

A multi-phase LLC power converter comprising:

• a plurality of LLC phases, each of the LLC phases comprising a resonant tank and a switching stage, the resonant tank including a resonant inductor, a resonant capacitor, and a parallel inductance, and the switching stage configured to switch an input power at an operating frequency to apply a switched power to the resonant tank, the switched power approximating an alternating current (AC) waveform having a switching frequency,
• a secondary-side controller configured to vary the switching frequency to control an output voltage of the multi-phase LLC power converter;
• and
• a primary-side controller configured to:
• calculate an initial switch-controlled capacitor (SCC) conduction phase angle for each of the LLC phases to cause each of the LLC phases to have equal resonant frequencies;
• and operate an SCC switch in accordance with an associated one of the SCC conduction phase angles to adjust the capacitance of the resonant capacitor of at least one of the plurality of LLC phases.

A multi-phase LLC power converter comprising:

• two LLC phases, each of the two LLC phases comprising a resonant tank and a switching stage, the resonant tank including a resonant inductor, a resonant capacitor, and a parallel inductance, and the switching stage configured to switch an input power at an operating frequency to apply a switched power to the resonant tank, the switched power approximating an alternating current (AC) waveform having a switching frequency,
• a secondary-side controller configured to vary the switching frequency to control an output voltage of the multi-phase LLC power converter;
• and
• a primary-side controller configured to:
• operate a switch-controlled capacitor (SCC) switch in accordance with an associated one of the SCC conduction phase angles to adjust the capacitance of the resonant capacitor of at least one of the plurality of LLC phases;
• wherein one of the two LLC phases is a reference phase having a fixed SCC conduction phase angle, and wherein the primary-side controller is configured to calculate an SCC conduction phase angle for the other one of the two LLC phases to cause each of the two LLC phases to have equal currents therethrough.