Abstract: A power conversion device includes: a power converter including, for respective phases of AC, leg circuits each including a pair of arms connected in series, the arms including a plurality of converter cells which are connected in series and each of which has an energy storage element and a plurality of semiconductor elements, the leg circuits being connected in parallel between positive and negative DC terminals, the power converter being configured to perform power conversion between multiphase AC and DC; and a control unit. The control unit corrects an AC voltage command value for controlling AC voltage of the power converter, by a zero-phase-sequence voltage command value having a set amplitude and a set phase, and performs adjustment control for adjusting at least either the amplitude or the phase of the zero-phase-sequence voltage command value on the basis of electric energy variation in the arm.

Abstract: The present disclosure suppresses increase in device cost in a DC power distribution system that can disconnect a distribution line on which a short-circuit failure has occurred, from an output path. This DC power distribution system includes: a plurality of power conversion devices; one DC busbar; a plurality of distribution lines; a plurality of first current interruption portions respectively connected to input sides of the power conversion devices; a plurality of second current interruption portions connected between the power conversion devices and the DC busbar; and a plurality of third current interruption portions respectively provided on the distribution lines. Interruption current values of the third current interruption portions are set to smaller values than a maximum allowable current value of the power conversion device in which short-circuit current will reach the maximum allowable current value in a shortest time.

Abstract: Unit converters each comprises a capacitor, a switching element having a flat surface on one side, a P-pole connection conductor where a second terminal hole at one end for fixing an electrode corresponding to a P-pole of the switching element and a first terminal hole at the other end for fixing a terminal of the capacitor are formed, and an N-pole connection conductor where a second terminal hole at one end for fixing an electrode corresponding to a N-pole of the switching element and a first terminal hole at the other end for fixing a terminal of the capacitor are formed. The unit-converters each including the connection conductors arranged to overlap in the thickness direction with their insulation maintained make the cooling surfaces of the switching elements be opposed to each other with a cooling device therebetween.

Abstract: A main circuit power feeder device for supplying control power from a main circuit power storage element to a main circuit control device includes: a plurality of voltage-division power storage elements connected in series; a voltage adjustment circuitry which is connected to the voltage-division power storage elements and adjusts voltages of the voltage-division power storage elements by mutual transfer of power among the voltage-division power storage elements; and a control circuitry which outputs control command values in two patterns that are a voltage-division control command value for dividing voltage of the main circuit power storage element among the voltage-division power storage elements and a bypass control command value for bypassing at least one voltage-division power storage element, in order to control the voltage adjustment circuitry, and which adjusts input voltage to the DC/DC converter.

Abstract: A multiwinding transformer includes a primary-side winding and a plurality of secondary-side windings. A primary-side bridge circuit is connected between a primary-side DC terminal and the primary-side winding. A plurality of secondary-side bridge circuits are connected between the plurality of secondary-side windings and a plurality of secondary-side DC terminals, respectively. A switching converter variably controls a first DC voltage of the primary-side DC terminal or a second DC voltage of a first secondary-side DC terminal among the plurality of secondary-side DC terminals such that a voltage ratio between the first DC voltage and the second DC voltage is controlled to a constant ratio in accordance with a turns ratio between the primary-side winding and the secondary-side winding corresponding to the first secondary-side DC terminal among the plurality of secondary-side windings.

Abstract: An object is to provide a DC distribution panel that, even when short-circuit current has occurred in one feeder, interrupts only the feeder where short-circuit current has occurred, and thus can continue operations of load apparatuses connected to normal feeders. This DC distribution panel includes: an input terminal including positive and negative input terminals; circuit breakers having short-circuit current interruption units connected to at least either of positive electric paths and negative electric paths respectively branched from the positive and negative input terminals; and output terminals including positive output terminals and negative output terminals of the plurality of circuit breakers. At least one of the plurality of circuit breakers includes a reverse current interruption unit for interrupting reverse current flowing through the positive electric path from the output terminal side to the input terminal side.

Abstract: The present DC power supply and distribution system includes a plurality of distribution lines provided respectively corresponding to a plurality of loads, a first converter to convert an AC voltage from a commercial AC power source into a plurality of DC voltages and supply the DC voltages respectively to the distribution lines, a second converter to convert a DC power from a power generation and storage source into a plurality of DC powers and supply the DC powers respectively to the distribution lines, and a power controller to control the DC powers such that the efficiency of the first converter is increased, based on information related to the efficiency of the second converter.

Abstract: A power supply system includes a power converter, a load state detector, and a controller. The power converter converts AC power received from the main power source into DC power with a voltage in accordance with a distribution voltage command value Vref and supplies the DC power to the load. The load state detector detects an operating state of the load. The controller operates in an operation mode selected from among a plurality of operation modes and generates the distribution voltage command value Vref. The operation modes include a distribution voltage control mode in which the distribution voltage command value Vref is generated based on load operating information detected by the load state detector and a distribution voltage fixed mode in which a predetermined setting value or an external command value acquired from an external device is set as the distribution voltage command value Vref.

Abstract: A power conversion device includes, for respective phases of an AC circuit, leg circuits each having a pair of arms connected in series to each other, each arm including a plurality of converter cells which are connected in series and each of which has an energy storage element. A controlling circuitry includes a zero-phase-sequence voltage command value adjustment unit for correcting arm voltage command values for the arms by a zero-phase-sequence voltage command value. The command value correction circuitry performs adjustment control for adjusting the zero-phase-sequence voltage command value so that at least one arm voltage command value becomes equivalent to a limit value of the output voltage range of the arm.

Abstract: An object is to obtain a power conversion device that can stabilize output voltage to a DC load. A power conversion device includes an AC/DC conversion unit having a power conversion circuit composed of a plurality of first semiconductor switching elements connected in a full-bridge form, and a full-bridge chopper circuit unit having a full-bridge chopper circuit composed of a plurality of second semiconductor switching elements connected in a full-bridge form, and connected to a positive terminal and a negative terminal. A neutral point of an AC filter capacitor unit and a neutral point of a DC filter capacitor unit are connected via a neutral point line.

Abstract: A multiwinding transformer includes a primary-side winding and a plurality of secondary-side windings. A primary-side bridge circuit to carry out DC/AC power conversion is connected between a primary-side DC terminal connected to a DC power supply and the primary-side winding. A plurality of secondary-side bridge circuits to carry out DC/AC power conversion are connected between the plurality of secondary-side windings and a plurality of secondary-side DC terminals, respectively. The plurality of secondary-side windings include a first secondary-side winding strongest in magnetic coupling to the primary-side winding and a second secondary-side winding weaker in magnetic coupling to the primary-side winding than the first secondary-side winding.

Abstract: Even when one power conversion device among a plurality of power conversion devices connected in parallel experiences a short circuit, the other power conversion devices having experienced no short circuit can be promptly restarted. Each power conversion device includes: a short circuit occurrence determination unit configured to determine, on the basis of a current value at an output terminal, whether or not a short circuit has occurred; a short circuit elimination determination unit configured to determine, on the basis of a current value and a voltage value at the output terminal, whether or not the short circuit has been eliminated; and a current interruption unit configured to, on the basis of determination by the short circuit occurrence determination unit and determination by the short circuit elimination determination unit, interrupt current that flows from a power conversion unit to the output terminal or cancel the interruption.

Abstract: A DC power distribution system includes: a transformer; a rectification device; a DC bus through which DC power flows; a plurality of DC branch lines branching off from the DC bus; an AC interrupting portion connected to an input side of the transformer; a first DC interrupting portion connected between the rectification device and the DC bus; and a plurality of second DC interrupting portions respectively provided to the plurality of DC branch lines. An interrupting-operation time for each second DC interrupting portion is set to be shorter than interrupting-operation times for the AC interrupting portion and the first DC interrupting portion. An inductance value of a short-circuit impedance of the transformer is set to a value at which short-circuit current can be limited to take a value not larger than a maximum current value permitted for the rectification device.

Abstract: The present disclosure suppresses increase in device cost in a DC power distribution system that can disconnect a distribution line on which a short-circuit failure has occurred, from an output path. This DC power distribution system includes: a plurality of power conversion devices; one DC busbar; a plurality of distribution lines; a plurality of first current interruption portions respectively connected to input sides of the power conversion devices; a plurality of second current interruption portions connected between the power conversion devices and the DC busbar; and a plurality of third current interruption portions respectively provided on the distribution lines. Interruption current values of the third current interruption portions are set to smaller values than a maximum allowable current value of the power conversion device in which short-circuit current will reach the maximum allowable current value in a shortest time.

Abstract: The present DC power supply and distribution system comprises: a plurality of power distribution lines each connected to a respective one of a plurality of loads; a first converter to receive an AC voltage from a commercial AC power source, convert the received AC voltage into a plurality of DC voltages and supply each of the plurality of DC voltages to a respective one of the plurality of power distribution lines; a second converter to receive a DC power from a power generating and/or storing source, convert the received DC power into a plurality of DC powers, and supply each of the plurality of DC powers to a respective one of the plurality of power distribution lines; and a controller to enhance the second converter in efficiency by controlling the first converter so that a ratio of the plurality of DC voltages is a predetermined first ratio.

Abstract: A power conversion device includes, for respective phases of an AC circuit, leg circuits each having a pair of arms connected in series to each other, each arm including a plurality of converter cells which are connected in series and each of which has an energy storage element. A controlling circuitry includes a zero-phase-sequence voltage command value adjustment unit for correcting arm voltage command values for the arms by a zero-phase-sequence voltage command value. The command value correction circuitry performs adjustment control for adjusting the zero-phase-sequence voltage command value so that at least one arm voltage command value becomes equivalent to a limit value of the output voltage range of the arm.

Abstract: A power conversion device includes: a power converter including, for respective phases of AC, leg circuits each including a pair of arms connected in series, the arms including a plurality of converter cells which are connected in series and each of which has an energy storage element and a plurality of semiconductor elements, the leg circuits being connected in parallel between positive and negative DC terminals, the power converter being configured to perform power conversion between multiphase AC and DC; and a control unit. The control unit corrects an AC voltage command value for controlling AC voltage of the power converter, by a zero-phase-sequence voltage command value having a set amplitude and a set phase, and performs adjustment control for adjusting at least either the amplitude or the phase of the zero-phase-sequence voltage command value on the basis of electric energy variation in the arm.

Abstract: In a start-up control in which primary-side direct-current (DC) terminals and secondary-side DC terminals are charged by an external power supply outside a power conversion device, initially, one-side DC terminals are charged by the external power supply while switching operations of the primary-side bridge circuit and the secondary-side bridge circuit are stopped. Subsequently, a bridge circuit that is connected to the DC terminals not charged by the external power supply stops the switching operation and operates in a diode rectifying mode, while a bridge circuit that is connected to the DC terminals charged by the external power supply performs the switching operation and outputs an AC voltage whose voltage pulse width has been subjected to a variable control so that the voltage pulse width is smaller for a greater voltage difference of the charged DC terminals from the uncharged DC terminals.

Abstract: Provided is a power conversion device capable of continuing the transmission of power even in the event of failure of a DC-to-DC converter cell. The power conversion device according to the present invention includes: a unit having a plurality of DC-to-DC converter cells; a short-circuit device that short-circuits a failed cell; and a control circuit that controls the plurality of DC-to-DC converter cells. The control circuit controls the voltage of a second cell terminal of a healthy cell included in a unit that includes the failed cell, based on a failed cell count m, so that the power of a first cell terminal and the power of the second cell terminal are matched.

Abstract: A submodule includes a bridge circuit including two main power semiconductors connected in series for performing power conversion by on/off control and an electric energy storage element connected in parallel with a path of the two main power semiconductors connected in series, a bypass unit including a bypass power semiconductor), a bypass unit drive device to drive the bypass unit, a first external terminal, and a second external terminal. The first external terminal is connected to a node between the two main power semiconductors. The power conversion apparatus further includes an optical power-feed system for feeding power to the bypass unit drive device.