Abstract: A method and apparatus for controlling a microgrid load. In one embodiment, the method comprises measuring at least one grid parameter of a microgrid transmission line coupled to a load in a microgrid; computing, using the at least one grid parameter and a droop control technique, at least one virtual set-point; determining a modification to operation of the load based on the at least one virtual set-point; and modifying operation of the load based on the modification.

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

Abstract: A method and apparatus for power converter current control. In one embodiment, the method comprises controlling an instantaneous current generated by a power converter such that that power converter appears, from the perspective of an AC line coupled to the power converter, as a virtual AC voltage source in series with a virtual impedance, wherein real and reactive phasor currents for the power converter are indirectly controlled by modifying amplitude and phase of a virtual AC voltage waveform that defines the virtual AC voltage source.

Abstract: Method and apparatus for controlling power conditioners in a distributed resource island. In one embodiment, the method comprises comparing, at a power conditioner operating in a de-energized state, an input of the power conditioner to an input threshold, wherein the power conditioner is coupled to an islanded grid; operating the power conditioner, when the input exceeds the input threshold, in a soft-grid mode to generate a touch-safe AC voltage that is coupled to the islanded grid; comparing, by the power conditioner, an impedance of the islanded grid to a grid impedance range; comparing, by the power conditioner, load demand of the power conditioner to an activate threshold; and activating the power conditioner, when the impedance is within the grid impedance range and the load demand exceeds the activate threshold, to operate proximate its nominal output voltage.

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 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: Method and apparatus for transmitting combined power and data. In one embodiment, the apparatus comprises an isolation barrier; a drive controller for generating a first waveform comprising a plurality of data signals for transmitting different types of data, where the drive controller couples the first waveform to a first side of the isolation barrier to produce a second waveform on a second side of the isolation barrier; and a circuit controller coupled to the second side of the isolation barrier, where the circuit controller is powered by the second waveform, and where the circuit controller controls a circuit based on the plurality of data signals.

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 method and apparatus for detecting a zero-voltage condition. In one embodiment, the method comprises generating a first current that is proportional to a voltage across a four-quadrant (4Q) switch; generating a reference current, wherein the reference current is equal to a value of the first current when of the voltage across the 4Q switch is at a predefined value; comparing the first current to the reference current; and generating an indication of a zero-voltage condition across the 4Q switch when the first current is less than the reference current.

Abstract: A method and apparatus for line-cycle storage of a single-phase cycloconverter. The method includes receiving input power from an input port of the singe-phase cycloconverter and monitoring an AC output port of the single-phase cycloconverter. The method measures energy stored in a line-cycle energy storage circuit coupled to one line of the AC output port of the single-phase cycloconverter, and determines a phase difference between a monitored AC voltage of the AC output port and the measured voltage of the line-cycle energy storage circuit. The method controls switches in the single-phase cycloconverter to selectively store energy in the line-cycle energy storage circuit based on the phase difference.

Abstract: A method and apparatus for multi phase shift control of a power converter. In one embodiment, the method comprises controlling a phase shift between a left leg and a right leg of a first bridge of the power converter during operation of the power converter; and controlling a phase shift between the first bridge and a second bridge of the power converter during the operation of the power converter, wherein the phase shift between the left and the right legs and the phase shift between the first and the second bridges are controlled based on an input voltage of the power converter and a required output voltage of the power converter.

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: 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 ratio based on both voltage and charge pertaining to power conversion in a resonant converter; comparing the ratio to a threshold; and controlling, independent of switching frequency of the resonant converter, power output from the resonant converter based on whether the ratio satisfies the threshold.

Abstract: System and apparatus for power conversion. In one embodiment, the apparatus comprising a DC stage, comprising a resonant circuit, for generating a high-frequency resonant current; and an AC stage for converting a high-frequency current, generated from the high-frequency resonant current, to an AC output current, wherein the AC stage comprises: a pair of serially-connected switches for (i) passing, during a first half of a cycle of an AC line, a positive portion of the high-frequency current, and (ii) passing, during a second half of the cycle of the AC line, a negative portion of the high-frequency current; and an unfurling bridge for unfurling a current waveform, formed from the positive and the negative portions, to generate the AC output current, wherein the unfurling bridge is operated at a frequency on the order of three orders of magnitude lower than an operating frequency of the serially-connected switches.

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 comprising a first secondary winding, a second secondary winding, and a third secondary winding, the first, the second, and the third secondary windings wound in a tri-filar configuration; and a cyclo-converter comprising a plurality of switch pairs for converting an alternating current to an AC current, each switch pair in the plurality of switch pairs coupled between two lines of an AC output and having a different secondary winding of the plurality of secondary windings coupled between its switches, the plurality of switch pairs comprising a first switch pair, a second switch pair, and a third switch pair, wherein the first, the second, and the third secondary windings are coupled between drain terminals of the first, the second, and the third switch pair, respectively.