Abstract: Provided is a power supply device in which the output voltages of unit power converters can be controlled to be substantially constant even when the loads of the respective unit power converters are different from each other. The power supply device in which a plurality of unit power converters are connected in series with an AC system and power is supplied from the unit power converters to load devices is characterized by being provided with a control device for obtaining the degree of load imbalance among the load powers of the load devices and controlling the AC system side voltages of the unit power converters to operate by reducing the power factor of the AC system when the degree of load imbalance increases.

Abstract: The present invention provides a transformer having a high degree of design freedom for adjusting leakage inductance, while conforming to arrangement constraints between components in order to ensure the insulating properties of the transformer. This transformer has a core formed of a magnetic body, a primary coil wound around the core and being connected to a high-voltage side, the primary coil having two coil layers of an inner primary coil and an outer primary coil arranged more toward an outer peripheral side than the inner primary coil, and a second primary coil wound around the core and connected to a low-voltage side, the outer primary coil being arranged offset with respect to the inner primary coil in the longitudinal direction of the axis of the core.

Abstract: Provided is a power conversion device that can be realized with a small circuit and is capable of stably converting AC power inputted from a three-phase power source system into DC power. In a power conversion device: an output terminal of a common converter cell in a J-numbered stage is connected, together with output terminals of common converter cells of the other two phases, to common lines; an output terminal of an independent converter cell in a K-numbered stage is connected to independent lines independently of converter cells of the other two phases; and a plurality of switches comprise a common switch for switching the connection relationship between the common lines and DC buses, and an independent switch for switching the connection relationship between the independent lines and DC buses.

Abstract: This bidirectional DC-DC converter comprises: a transformer; a first bridge circuit for converting DC power and AC power to each other which are input and output between a first DC power supply and the primary side of the transformer; a second bridge circuit for converting DC power and AC power to each other which are input and output between a second DC power supply and the secondary side of the transformer; a first resonant circuit connectable between the first bridge circuit and the primary side of the transformer; a second resonant circuit connectable between the second bridge circuit and the secondary side of the transformer; a first bypass switch for switching the connection state of the first resonant circuit between the first bridge circuit and the primary side of the transformer; a second bypass switch for switching the connection state of the second resonant circuit between the second bridge circuit and the secondary side of the transformer; and a control unit for controlling each of the first bypas

Abstract: An aspect of the present disclosure is a power conversion device including: a primary-side transformer to which a primary AC voltage is input from a primary-side circuit; and a secondary-side transformer that outputs a secondary AC voltage lower than the primary AC voltage to a secondary-side circuit. The primary-side transformer includes a primary-side primary winding to which the primary AC voltage is input, and a primary-side secondary winding to which power is transmitted from the primary-side primary winding. The secondary-side transformer includes a secondary-side primary winding constituting a closed circuit together with the primary-side secondary winding, and a secondary-side secondary winding to which power is transmitted from the secondary-side primary winding and which outputs the secondary AC voltage. The primary-side circuit and the closed circuit are connected to a common potential.

Abstract: An object of the present invention is to sufficiently reduce a switching loss. A control device causes a positive electrode of a first voltage to appear at a second connection point by switching second and third switching elements to an ON state. Next, the control device causes the positive electrode of the first voltage to appear at a first connection point by switching the second and third switching elements to an OFF state. After that, fifth and eighth switching elements are switched to the OFF state, and sixth and seventh switching elements are switched to the ON state.

Abstract: The power conversion device includes multiple converter cells. Each converter cell includes a pair of primary-side terminals and a pair of secondary-side terminals. The converter cell transmits power between the pair of primary-side terminals and the pair of secondary-side terminals. The primary-side terminals of the multiple converter cells are connected in series to a primary-side power supply system. The secondary-side terminals of the multiple converter cells are connected in series to a secondary-side power supply system. Among the multiple converter cells, the converter cell in which an absolute value of a ground voltage appearing in the pair of primary-side terminals is the highest is different from the converter cell in which an absolute value of a ground voltage appearing in the pair of secondary-side terminals is the highest.

Abstract: A power conversion device that suppresses voltage pulsation of a capacitor of a power converter with respect to a control target whose effective power is to be controlled is provided. The power conversion device includes a plurality of power conversion cells that are connected to each other, and convert a primary-side system voltage into a secondary-side system voltage, a capacitor that is connected to each of the plurality of power conversion cells, and a power conversion cell driver that drives the power conversion cells to add a 3N order higher-harmonic-wave voltage of each of alternating voltages of the plurality of power conversion cells to the each of alternating voltages, and output a voltage made by adding the each of alternating voltages and the 3N order higher-harmonic-wave voltage, when N is a natural number.

Abstract: An object of the present invention is to sufficiently reduce a switching loss. A control device causes a positive electrode of a first voltage to appear at a second connection point by switching second and third switching elements to an ON state. Next, the control device causes the positive electrode of the first voltage to appear at a first connection point by switching the second and third switching elements to an OFF state. After that, fifth and eighth switching elements are switched to the OFF state, and sixth and seventh switching elements are switched to the ON state.

Abstract: The power conversion device includes multiple converter cells. Each converter cell includes a pair of primary-side terminals and a pair of secondary-side terminals. The converter cell transmits power between the pair of primary-side terminals and the pair of secondary-side terminals. The primary-side terminals of the multiple converter cells are connected in series to a primary-side power supply system. The secondary-side terminals of the multiple converter cells are connected in series to a secondary-side power supply system. Among the multiple converter cells, the converter cell in which an absolute value of a ground voltage appearing in the pair of primary-side terminals is the highest is different from the converter cell in which an absolute value of a ground voltage appearing in the pair of secondary-side terminals is the highest.

Abstract: A power conversion device that suppresses voltage pulsation of a capacitor of a power converter with respect to a control target whose effective power is to be controlled is provided. The power conversion device includes a plurality of power conversion cells that are connected to each other, and convert a primary-side system voltage into a secondary-side system voltage, a capacitor that is connected to each of the plurality of power conversion cells, and a power conversion cell driver that drives the power conversion cells to add a 3N order higher-harmonic-wave voltage of each of alternating voltages of the plurality of power conversion cells to the each of alternating voltages, and output a voltage made by adding the each of alternating voltages and the 3N order higher-harmonic-wave voltage, when N is a natural number.

Abstract: A power conversion device includes three first power conversion cells each converting input power and outputting the converted power and having input terminals connected in parallel regarding a first power supply and three second power conversion cells each converting input power and outputting the converted power and having input terminals connected in parallel regarding a second power supply, wherein: the power output from the cell and the power output from the cell are combined to output a first phase power; the power output from the cell and the power output from the cell are combined to output a second phase power; and the power output from the cell and the power output from the cell are combined to output a third phase power. The first phase, second phase, and third phase powers are output as the phase powers or inter-line powers of a three-phase system.

Abstract: In a power conversion device, a power conversion unit includes a single-phase inverter on a secondary side of a resonant type converter that has an input of a direct current. A power conversion unit group is configured by connecting outputs of the single-phase inverters of a plurality of power conversion units in series. Respective phases of three phase alternate current are formed with the three power conversion unit groups housed in a power conversion device housing. The plurality of power conversion units constituting the power conversion unit group are disposed along a longitudinal direction of the power conversion device housing. The respective three power conversion unit groups are disposed at an upper stage, a middle stage, and a lower stage in a height direction of the power conversion device housing. The power conversion device housing has one end side in the longitudinal direction as output terminals of the three power conversion unit groups.

Abstract: In a power conversion device, a power conversion unit includes a single-phase inverter on a secondary side of a resonant type converter that has an input of a direct current. A power conversion unit group is configured by connecting outputs of the single-phase inverters of a plurality of power conversion units in series. Respective phases of three phase alternate current are formed with the three power conversion unit groups housed in a power conversion device housing. The plurality of power conversion units constituting the power conversion unit group are disposed along a longitudinal direction of the power conversion device housing. The respective three power conversion unit groups are disposed at an upper stage, a middle stage, and a lower stage in a height direction of the power conversion device housing. The power conversion device housing has one end side in the longitudinal direction as output terminals of the three power conversion unit groups.

Abstract: A power conversion device includes three first power conversion cells each converting input power and outputting the converted power and having input terminals connected in parallel regarding a first power supply and three second power conversion cells each converting input power and outputting the converted power and having input terminals connected in parallel regarding a second power supply, wherein: the power output from the cell and the power output from the cell are combined to output a first phase power; the power output from the cell and the power output from the cell are combined to output a second phase power; and the power output from the cell and the power output from the cell are combined to output a third phase power. The first phase, second phase, and third phase powers are output as the phase powers or inter-line powers of a three-phase system.

Abstract: If an input voltage of a DC/DC converter is lower than a first voltage value that is set in advance, a converter controller maintains an output voltage of the DC/DC converter within a first voltage range that is set in advance by changing an operation frequency of switching of the DC/DC converter in compliance with the input voltage as a first voltage maintaining control. If the input voltage is higher than a second voltage value that is higher than the first voltage value, the converter controller maintains the output voltage within a second voltage range that is higher than the first voltage range by changing the operation frequency in compliance with the input voltage as a second voltage maintaining control.

Abstract: Reduction in size and weight of transformer for grid tie applications is demanded and can be achieved by applying SST to the transformer. However, SST application to PCS for sunlight requires the following: handle a wide variation range of the voltage of solar power generation; reduce switching losses of power devices, DC/DC converter and inverter, in the power circuit to implement high frequency for SST application; increase voltage to the grid voltage; and reduce the dimensions of the high current path prior to step-up. Thus, LLC resonant converter configuration is applied with an inverter placed in the output, and series connected configuration is applied to the inverter. The LLC resonant converter is subject to constant frequency regulation with large output, step-up control with low output, and step-down control with the upper limit voltage according to MPPT voltage from sunlight, in order to achieve drive loss reduction and voltage range handling.

Abstract: Size and weight reduction of a transformer for system interconnection is needed. Applying an SST to the transformer can reduce the size and weight. However, it is also necessary to flexibly handle a wide range of voltages to match a high-voltage system or motor, reduce switching loss of a power device used in a power circuit such as a DC/DC converter and an inverter in association with frequency increase caused by application of the SST, and achieve size reduction of a cooling structure. Further, it is necessary to boost a voltage to a system voltage and reduce the size and weight of a large current path before the voltage boosting. Thus, an LLC resonant converter structure is applied, and a multiple-connection structure is employed in each of which a converter is arranged for an input or an inverter is arranged for an output. This enables handling of various voltage ranges by various combinations of the numbers of multiple connections of the inputs and the outputs.

Abstract: Reduction in size and weight of transformer for grid tie applications is demanded and can be achieved by applying SST to the transformer. However, SST application to PCS for sunlight requires the following: handle a wide variation range of the voltage of solar power generation; reduce switching losses of power devices, DC/DC converter and inverter, in the power circuit to implement high frequency for SST application; increase voltage to the grid voltage; and reduce the dimensions of the high current path prior to step-up. Thus, LLC resonant converter configuration is applied with an inverter placed in the output, and series connected configuration is applied to the inverter. The LLC resonant converter is subject to constant frequency regulation with large output, step-up control with low output, and step-down control with the upper limit voltage according to MPPT voltage from sunlight, in order to achieve drive loss reduction and voltage range handling.

Abstract: Size and weight reduction of a transformer for system interconnection is needed. Applying an SST to the transformer can reduce the size and weight. However, it is also necessary to flexibly handle a wide range of voltages to match a high-voltage system or motor, reduce switching loss of a power device used in a power circuit such as a DC/DC converter and an inverter in association with frequency increase caused by application of the SST, and achieve size reduction of a cooling structure. Further, it is necessary to boost a voltage to a system voltage and reduce the size and weight of a large current path before the voltage boosting. Thus, an LLC resonant converter structure is applied, and a multiple-connection structure is employed in each of which a converter is arranged for an input or an inverter is arranged for an output. This enables handling of various voltage ranges by various combinations of the numbers of multiple connections of the inputs and the outputs.