A resonant converter includes a primary stage having first and second switches coupled in series, a controller coupled to the first switch and the second switch to control operation thereof, a first transformer comprising a primary coil coupled to a node between the first and second switches, and a resonant inductor coupled to the primary coil of the first transformer. The resonant converter also includes a secondary stage having a second transformer formed of a primary coil coupled to the resonant inductor and a secondary coil comprising first and second coil sections, a third switch coupled to the first coil section of the secondary coil, and a fourth switch coupled to the second coil section of the secondary coil. A switch drive circuit is provided to drive the third and fourth switches for synchronous rectification, with the switch drive circuit comprising a secondary coil of the first transformer.

A DC/DC flyback converter that exhibits reduced switch and transformer voltage stresses in comparison to known flyback converters. The flyback converter also employs soft switching. Embodiments of such flyback converters may be used, without limitation, in electric vehicles and hybrid electric vehicles. A front-stage of the flyback converter comprises a DC/AC step-down circuit that may be separately used for various purposes.

A DC/DC flyback converter that exhibits reduced switch and transformer voltage stresses in comparison to known flyback converters. The flyback converter also employs soft switching. Embodiments of such flyback converters may be used, without limitation, in electric vehicles and hybrid electric vehicles. A front-stage of the flyback converter comprises a DC/AC step-down circuit that may be separately used for various purposes.

A frequency stabilizer includes a bidirectional AC/DC converter, a bidirectional DC/DC converter, a first energy storage system, a second energy storage system, and a building. The bidirectional AC/DC converter is connected between an AC power system and the first energy storage system. The bidirectional DC/DC converter is connected between the first energy storage system and the second energy storage system. Two or more of the first energy storage system, the second energy storage system, the bidirectional AC/DC converter, and the bidirectional DC/DC converter are disposed inside the building.

A frequency stabilizer includes a bidirectional AC/DC converter, a bidirectional DC/DC converter, a first energy storage system, a second energy storage system, and a building. The bidirectional AC/DC converter is connected between an AC power system and the first energy storage system. The bidirectional DC/DC converter is connected between the first energy storage system and the second energy storage system. Two or more of the first energy storage system, the second energy storage system, the bidirectional AC/DC converter, and the bidirectional DC/DC converter are disposed inside the building.

Approaches for controlling power supplied to an electric grid are disclosed. In embodiments, methods and systems control power supplied to an electric grid using an energy storage device. In an embodiment, a method receives an indication of power to be supplied to the electric grid, generates power from a power generator and adjusts, using the generated power, an energy level of the energy storage device to control power supplied to the grid in accordance with the received indication. In another embodiment, a system comprises a grid indication receiver for receiving an indication of power to be supplied to the electric grid; a power generator connected to the grid; an energy storage device coupled to the power generator; and a controller for adjusting, using the generated power from the generator, an energy level of the energy storage device to control power supplied to the grid in accordance with the received indication.

Approaches for controlling power supplied to an electric grid are disclosed. In embodiments, methods and systems control power supplied to an electric grid using an energy storage device. In an embodiment, a method receives an indication of power to be supplied to the electric grid, generates power from a power generator and adjusts, using the generated power, an energy level of the energy storage device to control power supplied to the grid in accordance with the received indication. In another embodiment, a system comprises a grid indication receiver for receiving an indication of power to be supplied to the electric grid; a power generator connected to the grid; an energy storage device coupled to the power generator; and a controller for adjusting, using the generated power from the generator, an energy level of the energy storage device to control power supplied to the grid in accordance with the received indication.

A three-phase inverter system, in one configuration, includes an inverter main circuit and a control circuit. The inverter system includes current sensors which detect output currents in, for example, U- and W-phases, respectively, the inverter main circuit includes a semiconductor switching device with a current sense which is provided in, for example, the V-phase. The control circuit is configured to detect current values from the current sensors inputted thereto and produce driving signals, which drive the upper-arm and lower-arm semiconductor switching devices of the inverter main circuit, based on the detected current values, estimate, based on a detected signal from the semiconductor switching device with the current sense, an output current value in the one of the three series circuits, and detect failure in at least one of the current sensors based on the detected current values from the two current sensors and the estimated output current value.

A charging device according to an exemplary embodiment of the present invention may include: a battery adapted and configured to store a DC voltage, first and second motors adapted and configured to operate as a motor or a generator, first and second inverters adapted and configured to operate the first and second motors, a voltage transformer adapted and configured to boost the DC voltage of the battery to supply it to the first and second inverters and boosts the DC voltage of the inverter to supply it to the battery, and a charging controller adapted and configured to operate the first and second inverters as a booster or operate the voltage transformer as a buck booster according to a voltage that is input through a neutral point of the first and second motors and the voltage of the battery.

A charging device according to an exemplary embodiment of the present invention may include: a battery adapted and configured to store a DC voltage, first and second motors adapted and configured to operate as a motor or a generator, first and second inverters adapted and configured to operate the first and second motors, a voltage transformer adapted and configured to boost the DC voltage of the battery to supply it to the first and second inverters and boosts the DC voltage of the inverter to supply it to the battery, and a charging controller adapted and configured to operate the first and second inverters as a booster or operate the voltage transformer as a buck booster according to a voltage that is input through a neutral point of the first and second motors and the voltage of the battery.