Abstract: Method and apparatus for power conversion. In one embodiment, the method comprises operating a resonant converter in a ring mode comprising (i) holding a plurality of switches of the resonant converter in a first switching state throughout a pre-determined number of resonant periods; and (ii) maintaining the plurality of switches in the first switching state for a fraction of a subsequent resonant period until an amount of energy has been transferred through the resonant converter to achieve a pre-determined output power from the resonant converter.

Abstract: A transformer assembly. In some embodiments, the transformer assembly comprises a transformer, comprising a magnetic core; a primary winding wound around the magnetic core, wherein the primary winding comprises one or two turns of a first conductive material; and a secondary winding wound around the magnetic core, wherein the secondary winding comprises a plurality of turns of a second conductive material, and wherein a diameter of the magnetic core is sized such that the transformer achieves a first inductance with a core loss comparable to a winding loss.

Abstract: A method and apparatus for providing AC power. In one embodiment, the apparatus comprises a cycloconverter controller for determining a DC value based on a reference waveform and a three-phase cycloconverter, coupled to the cycloconverter controller, for selectively coupling, based on the DC value, an alternating current to an AC line to generate a single-phase AC output.

Abstract: An apparatus and system for power conversion. In one embodiment, the apparatus comprises a transformer having a primary winding and a plurality of secondary windings; and a cyclo-converter comprising a plurality of switch pairs for converting an alternating current to an AC current, wherein each switch pair in the plurality of switch pairs (i) is coupled between two lines of an AC output and (ii) has a different secondary winding of the plurality of secondary windings coupled between its switches.

Abstract: A method and apparatus for controlling power conversion. In one embodiment, the method comprises computing a voltage ratio based on a voltage conversion in a resonant converter; comparing the voltage ratio to a threshold; and controlling, independent of switching frequency of the resonant converter, power output from the resonant converter based on whether the voltage ratio satisfies the threshold.

Abstract: A four quadrant bidirectional switch. In one embodiment, the four quadrant bidirectional switch comprises a first switch, a second switch, and a third switch, wherein (i) the first and second switches are normally-off switches, (ii) the third switch is a dual-gate, bidirectional, normally-on switch, and (iii) the first, the second, and the third switches are coupled to one another in a bi-cascode configuration.

Abstract: A method and apparatus for controlling resonant converter power production. In one embodiment, the method comprises determining accumulated charge processed by a resonant converter; dynamically determining a level of the accumulated charge that generates a predetermined output power; and controlling a switching cycle of the resonant converter based on the level of the accumulated charge.

Abstract: A method and apparatus for providing multi-phase power. In one embodiment, the apparatus comprises a cycloconverter controller for determining a charge ratio based on a reference waveform; and a cycloconverter, coupled to the cycloconverter controller and to a multi-phase AC line, for selectively coupling an alternating current to each line of the multi-phase AC line based on the charge ratio.

Abstract: A method for operating a DC-DC converter. The method comprises: matching, based on a turns ratio of a transformer of the DC-DC converter, a primary side capacitance of the DC-DC converter and a secondary side capacitance of the DC-DC converter to result in a matched capacitance; and operating the DC-DC converter with at least one operating parameter set to cause a primary current to oscillate between a peak value and zero such that a valley of the primary current coincides with a zero crossing of a secondary switching element voltage.

Abstract: A transformer assembly. In some embodiments, the transformer assembly comprises a transformer, comprising a magnetic core; a primary winding wound around the magnetic core, wherein the primary winding comprises one or two turns of a first conductive material; and a secondary winding wound around the magnetic core, wherein the secondary winding comprises a plurality of turns of a second conductive material, and wherein a diameter of the magnetic core is sized such that the transformer achieves a first inductance with a core loss comparable to a winding loss.