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: 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: A power supply device of the invention includes a first switching leg including first and second switching elements between DC terminals; a second switching leg including third and fourth switching elements between the DC terminals; a first capacitor leg including first and second capacitors between the DC terminals; a second capacitor leg including third and fourth capacitors between AC terminals; a first inductor between a connection of the first and second switching elements and one of the AC terminals; a second inductor between a connection of the third and fourth switching elements and another of the AC terminals; a controller; an AC power supply connected to the AC terminals and the connection of the third and fourth capacitors; and a DC power supply between the DC terminals, wherein the controller charges the first and second capacitors to a voltage higher than a voltage crest of the AC power supply.

Abstract: Disclosed is a charging system for both plug-in charging systems and contactless charging systems, having a simple electrical configuration, and capable of achieving miniaturization and weight saving. The charging system includes a secondary cell charged via first/second coils of a transformer to which electrical power is supplied from a first power supply via a plug-in connector, and a third coil supplied with electrical power from a second power supply, a relative position of which to the second coil of the transformer is variable, and which can be magnetically coupled to the second coil when the second coil approaches the third coil, wherein the secondary cell is charged via magnetic coupling between first/second coils when charging the secondary cell by the first power supply, and the secondary cell is charged via magnetic coupling between the third coil and second coils when charging the secondary cell by the second power supply.

Abstract: A highly efficient power supply unit compatible with a single-phase three-wire system and an operating method of such a power supply unit are provided. The power supply unit includes first and second switching legs connected in parallel to a first capacitor leg with a DC power supply connected thereto. One end of the second capacitor leg is connected to the middle point of the first switching leg through a first inductor, and the other end is connected to the middle point of the second switching leg through a second inductor. The two ends of the second capacitor leg and the middle point of the second capacitor leg are defined as AC terminals. A switch is provided between middle points of first and second capacitor legs. A control part sets the switch to OFF when power is input/output only between one end of the second capacitor leg and the other end.

Abstract: In a DC-DC converter, a smoothing capacitor is connected between DC terminals of the switching circuit, and a smoothing capacitor and a voltage clamp circuit are connected between DC terminals of a switching circuit, the voltage clamp circuit including the switching device and the clamp capacitor. The smoothing capacitors are connected to the DC power sources) in parallel, respectively. The winding of the switching circuit is magnetically coupled to the winding of the switching circuit by the transformer. The DC-DC converter performs a discharging operation for discharging the clamp capacitor between at least one of the step-down operation and a step-up operation and a step-up operation performed thereafter.

Abstract: A high-efficiency power supply apparatus is provided in light of the reduction of the switching loss. The power supply apparatus connected between the AC power supply and the DC load converts the AC power supplied from the AC power supply to the DC power and supplies it to the DC load. The power supply apparatus comprises the first switching circuit for outputting the switched positive and negative voltages to the primary winding of the transformer, a second switching circuit for supplying the DC power induced in the secondary winding of the transformer and switched to the DC load connected to the second AC terminals, a resonance inductor serial-connected to the primary winding, and a control unit for controlling the switching operations performed by the first and second switching circuits. The control unit substantially short-circuits the second AC terminals by controlling the switching operations performed by the second switching circuit.

Abstract: Provided is a vehicle which enables a highly-efficient DC-DC converter and a highly-efficient power supply to a load, regardless of a power supply amount of to the load. When the power supply amount to a load R1 is a predetermined value or more, a control means 5 implements a first mode for making the switching elements S1 to S4 driven, and when the power supply amount of to the load R1 is the predetermined value or less, the control means 5 implements a second mode, for making the switching elements S3 and S4 stopped in an OFF state, and making only the switching elements S1 and S2 driven.

Abstract: A power supply device of the invention includes a first switching leg including first and second switching elements between DC terminals; a second switching leg including third and fourth switching elements between the DC terminals; a first capacitor leg including first and second capacitors between the DC terminals; a second capacitor leg including third and fourth capacitors between AC terminals; a first inductor between a connection of the first and second switching elements and one of the AC terminals; a second inductor between a connection of the third and fourth switching elements and another of the AC terminals; a controller; an AC power supply connected to the AC terminals and the connection of the third and fourth capacitors; and a DC power supply between the DC terminals, wherein the controller charges the first and second capacitors to a voltage higher than a voltage crest of the AC power supply.

Abstract: Provided is a vehicle which enables a highly-efficient DC-DC converter and a highly-efficient power supply to a load, regardless of a power supply amount of to the load. When the power supply amount to a load R1 is a predetermined value or more, a control means 5 implements a first mode for making the switching elements S1 to S4 driven, and when the power supply amount of to the load R1 is the predetermined value or less, the control means 5 implements a second mode, for making the switching elements S3 and S4 stopped in an OFF state, and making only the switching elements S1 and S2 driven.

Abstract: A highly efficient power supply unit compatible with a single-phase three-wire system and an operating method of such a power supply unit are provided. The power supply unit includes first and second switching legs connected in parallel to a first capacitor leg with a DC power supply connected thereto. One end of the second capacitor leg is connected to the middle point of the first switching leg through a first inductor, and the other end is connected to the middle point of the second switching leg through a second inductor. The two ends of the second capacitor leg and the middle point of the second capacitor leg are defined as AC terminals. A switch is provided between middle points of first and second capacitor legs. A control part sets the switch to OFF when power is input/output only between one end of the second capacitor leg and the other end.

Abstract: Disclosed is a small-size, high-efficiency, isolated, bidirectional DC-DC converter. The bidirectional DC-DC converter includes a transformer in which windings are magnetically coupled, switching circuits, a diode which is connected in parallel with a switch, smoothing capacitors, and a control section. First and second DC power supplies, which are connected in parallel with the smoothing capacitors, respectively, provide bidirectional electrical power transfer. When electrical power is to be transferred from the first DC power supply to the second DC power supply, the switch is maintained in the ON state. When, on the other hand, electrical power is to be transferred from the second DC power supply to the first DC power supply, the switch is maintained in the OFF state to prevent a reverse electrical power flow from the first DC power supply.

Abstract: Disclosed is a charging system for both plug-in charging systems and contactless charging systems, having a simple electrical configuration, and capable of achieving miniaturization and weight saving. The charging system includes a secondary cell charged via first/second coils of a transformer to which electrical power is supplied from a first power supply via a plug-in connector, and a third coil supplied with electrical power from a second power supply, a relative position of which to the second coil of the transformer is variable, and which can be magnetically coupled to the second coil when the second coil approaches the third coil, wherein the secondary cell is charged via magnetic coupling between first/second coils when charging the secondary cell by the first power supply, and the secondary cell is charged via magnetic coupling between the third coil and second coils when charging the secondary cell by the second power supply.

Abstract: Disclosed is a small-size, high-efficiency, isolated, bidirectional DC-DC converter. The bidirectional DC-DC converter includes a transformer in which windings are magnetically coupled, switching circuits, a diode which is connected in parallel with a switch, smoothing capacitors, and a control section. First and second DC power supplies, which are connected in parallel with the smoothing capacitors, respectively, provide bidirectional electrical power transfer. When electrical power is to be transferred from the first DC power supply to the second DC power supply, the switch is maintained in the ON state. When, on the other hand, electrical power is to be transferred from the second DC power supply to the first DC power supply, the switch is maintained in the OFF state to prevent a reverse electrical power flow from the first DC power supply.

Abstract: Provided is a vehicle which enables a highly-efficient DC-DC converter and a highly-efficient power supply to a load, regardless of a power supply amount of to the load. When the power supply amount to a load R1 is a predetermined value or more, a control means 5 implements a first mode for making the switching elements S1 to S4 driven, and when the power supply amount of to the load R1 is the predetermined value or less, the control means 5 implements a second mode, for making the switching elements S3 and S4 stopped in an OFF state, and making only the switching elements S1 and S2 driven.

Abstract: Disclosed is a small-size, high-efficiency, isolated, bidirectional DC-DC converter. The bidirectional DC-DC converter includes a transformer in which windings are magnetically coupled, switching circuits, a diode which is connected in parallel with a switch, smoothing capacitors, and a control section. First and second DC power supplies, which are connected in parallel with the smoothing capacitors, respectively, provide bidirectional electrical power transfer. When electrical power is to be transferred from the first DC power supply to the second DC power supply, the switch is maintained in the ON state. When, on the other hand, electrical power is to be transferred from the second DC power supply to the first DC power supply, the switch is maintained in the OFF state to prevent a reverse electrical power flow from the first DC power supply.

Abstract: A high-efficiency power supply apparatus is provided in light of the reduction of the switching loss. The power supply apparatus connected between the AC power supply and the DC load converts the AC power supplied from the AC power supply to the DC power and supplies it to the DC load. The power supply apparatus comprises the first switching circuit for outputting the switched positive and negative voltages to the primary winding of the transformer, a second switching circuit for supplying the DC power induced in the secondary winding of the transformer and switched to the DC load connected to the second AC terminals, a resonance inductor serial-connected to the primary winding, and a control unit for controlling the switching operations performed by the first and second switching circuits. The control unit substantially short-circuits the second AC terminals by controlling the switching operations performed by the second switching circuit.

Abstract: To provide an AC-DC converter that is highly efficient in a broad load current range from a light load to a heavy load. An AC-DC converter 1 has a main circuit and a control means 4; the main circuit includes a diode bridge circuit 3, a main inductor L1, a main switching element S1, a main diode D1, an auxiliary inductor L2, an auxiliary switching element S2, an auxiliary diode D2, and a smoothing capacitor C1 connected to a DC load 12. The AC-DC converter 1 supplies electric power from an AC power supply 11 to the DC load 12. In a period during which the instantaneous value of an input current from the AC power supply 11 is smaller than a prescribed value Ith, the AC-DC converter 1 stops the main switching element S1 and performs electricity conversion in hard switching by the operation of the auxiliary switching element S2.

Abstract: A small and efficient DC-DC converter is provided. In this DC-DC converter, passive elements such as an inductor and a capacitor can be reduced in size by reducing switching loss by a soft switching technology and increasing the drive frequency of a switching element. The DC-DC converter has a main switching element, a main diode and an auxiliary circuit that discharges the electric charges of the capacitance between the ends of the main switching element. The DC-DC converter includes an auxiliary inductor magnetically coupled with the main inductor, an auxiliary switching element that stores energy in the auxiliary inductor, and an auxiliary diode that discharges energy stored in the auxiliary inductor to the direct-current power source or the output side. The auxiliary inductor is coupled with the main inductor in the direction in which backward voltage is applied to the auxiliary diode when the main inductor discharges energy.