Power conditioner, control device, and power supply system

Abstract

A power conditioner (10) comprises a first connection terminal (11), a bidirectional DC / DC converter (12), a first relay (13), a first voltage sensor (14), a bidirectional inverter (15), and a control unit (16). The bidirectional DC / DC converter (12) is connected to the first connection terminal (11). The first relay (13) opens and closes an electrical connection between the first connection terminal (11) and the bidirectional DC / DC converter (12). The first voltage sensor (14) detects a voltage between the first connection terminal (11) and the first relay (13). The control unit (16) causes the bidirectional inverter (15) to carry out AC / DC conversion in the connection sequence. The control unit (16) switches the first relay (13) to ON after adjusting the DC voltage output from the bidirectional DC / DC converter (12) to the first connection terminal side to a first voltage in the connection sequence.

Description

Power conditioner, control device, and power supply system CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2023-203289, filed on November 30, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a power conditioner, a control device, and a power supply system.

[0003] Power conditioners are used to connect DC power supply units, such as storage battery devices and solar power generation devices, that output DC power to power grids that supply AC power. When connecting a power conditioner to a DC power supply unit, an inrush current caused by the DC power output from the DC power supply unit may flow into the power conditioner. The inrush current may damage electronic components, such as capacitors and coils, inside the power conditioner. Therefore, it has been proposed to provide an inrush current prevention circuit in the power conditioner (see Patent Document 1).

[0004] JP 2013-078183 A

[0005] a bidirectional DC / DC converter connected to the connection terminal; a relay that opens and closes an electrical connection between the connection terminal and the bidirectional DC / DC converter; a voltage sensor that detects a voltage between the connection terminal and the relay; a bidirectional inverter electrically connected to the bidirectional DC / DC converter; and a control unit that, in a connection sequence with the DC power supply unit, causes the bidirectional inverter to perform AC / DC conversion to output a DC voltage to the bidirectional DC / DC converter, and adjusts the DC voltage output from the bidirectional DC / DC converter to the connection terminal to a first voltage, and then switches the relay ON.

[0006] A control device according to a second aspect includes a power conditioner having connection terminals for a DC power supply unit, a bidirectional DC / DC converter connected to the connection terminals, a relay that opens and closes an electrical connection between the connection terminals and the bidirectional DC / DC converter, a voltage sensor that detects a voltage between the connection terminals and the relay, and a bidirectional inverter electrically connected to the bidirectional DC / DC converter, and includes a control unit that, in a connection sequence between the DC power supply unit and the power conditioner, causes the bidirectional inverter to perform AC / DC conversion to output a DC voltage to the bidirectional DC / DC converter, adjusts the DC voltage output from the bidirectional DC / DC converter to the connection terminals to a first voltage, and then switches the relay on.

[0007] A power supply system according to a third aspect includes: a DC power supply unit capable of outputting DC power; a power conditioner having connection terminals for the DC power supply unit, a bidirectional DC / DC converter connected to the connection terminals, a relay for opening and closing an electrical connection between the connection terminals and the bidirectional DC / DC converter, a voltage sensor for detecting a voltage between the connection terminals and the relay, and a bidirectional inverter electrically connected to the bidirectional DC / DC converter; and a control device for, in a connection sequence between the power conditioner and the DC power supply unit, causing the bidirectional inverter to perform AC / DC conversion to output a DC voltage to the bidirectional DC / DC converter side, and adjusting the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage, and then switching the relay ON.

[0008] It is a configuration diagram showing a schematic configuration of a power conditioner according to the present embodiment. It is a flowchart for explaining a connection sequence process executed by a control unit of the power conditioner of FIG.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same components are denoted by the same reference numerals.

[0010] 1 , a power conditioner 10 according to an embodiment of the present disclosure includes a first connection terminal 11, a bidirectional DC / DC converter 12, a first relay 13, a first voltage sensor 14, a bidirectional inverter 15, and a control unit 16. The power conditioner 10 may further include a communication unit 17, an input capacitor 18, an intermediate link capacitor 19, a second relay 21, a second connection terminal 20, and a second voltage sensor 22.

[0011] The first connection terminal 11 is a connection terminal for the DC power supply unit 23. The connection terminal 11 for the DC power supply unit 23 is a terminal for connection to the DC power supply unit 23 and is used at least for inputting power output by the DC power supply unit 23. In a configuration in which the DC power supply unit 23 is a storage battery device, the first connection terminal 11 may be used for outputting power to the DC power supply unit 23. The DC power supply unit 23 is a device that can at least output DC power, such as a solar power generation device, a storage battery device, or a fuel cell device. In the following description, the DC power supply unit 23 is a storage battery device. The first connection terminal 11 of the storage battery device may include a positive terminal 11a and a negative terminal 11b.

[0012] The second connection terminal 20 may be a terminal for connecting to a power grid that supplies AC power. The second connection terminal 20 is assumed to be connected to a commercial grid 24, for example.

[0013] The bidirectional DC / DC converter 12 is connected to the first connection terminal 11. The bidirectional DC / DC converter 12 is electrically connected to the bidirectional inverter 15. The bidirectional DC / DC converter 12 is capable of adjusting a DC voltage. Specifically, the bidirectional DC / DC converter 12 adjusts the DC on the first connection terminal 11 side to a specific voltage value, and outputs the adjusted DC voltage to the bidirectional inverter 15. The bidirectional DC / DC converter 12 also adjusts the DC voltage on the bidirectional inverter 15 side to a specific voltage value, and outputs the adjusted DC voltage to the first connection terminal 11 side.

[0014] The first relay 13 is provided between the first connection terminal 11 and the bidirectional DC / DC converter 12. The first relay 13 may be provided on at least one of the positive terminal 11a side and the negative terminal 11b side. The first relay 13 may be provided, for example, on the positive terminal 11a side. The first relay 13 opens and closes the electrical connection between the first connection terminal 11 and the bidirectional DC / DC converter 12. The first relay 13 may, for example, interrupt current in an OFF state. The first relay 13 may, for example, conduct current in an ON state.

[0015] The second relay 21 may be provided between the second connection terminal 20 and the bidirectional inverter 15. The second relay 21 may be provided on at least one of the connection terminals 20. The second relay 21 opens and closes the electrical connection between the second connection terminal 20 and the bidirectional inverter 15. For example, the second relay 21 may interrupt current in an OFF state. For example, the second relay 21 may conduct current in an ON state.

[0016] The first voltage sensor 14 detects the voltage between the first connection terminal 11 and the first relay 13. The voltage may be the potential difference between the positive terminal 11a and the negative terminal 11b.

[0017] The second voltage sensor 22 may detect the voltage on the first connection terminal 11 side of the bidirectional DC / DC converter 12. In other words, the second voltage sensor 22 may detect the voltage between the first relay 13 and the bidirectional DC / DC converter 12.

[0018] The bidirectional inverter 15 may convert an AC voltage to a DC voltage, or convert a DC voltage to an AC voltage. In the following description, converting an AC voltage to a DC voltage is also referred to as AC-DC conversion. The bidirectional inverter 15 may be connected to the bidirectional DC / DC converter 12 on the DC side. The bidirectional inverter 15 may also be connected to the second connection terminal 20 on the AC side.

[0019] The communication unit 17 may communicate information with an external device. For example, the communication unit 17 may communicate with the DC power supply unit 23. The communication unit 17 may also communicate with a server via a network, for example.

[0020] The input capacitor 18 is connected in parallel to the bidirectional DC / DC converter 12. More specifically, the input capacitor 18 is connected to the connection terminal 11 side of the bidirectional DC / DC converter 12. The input capacitor 18 may be built into the bidirectional DC / DC converter 12. The input capacitor 18 is, for example, a smoothing capacitor.

[0021] The intermediate link capacitor 19 is connected in parallel to the bidirectional inverter 15. More specifically, the intermediate link capacitor 19 is connected to the DC side output terminal of the bidirectional inverter 15. The intermediate link capacitor 19 may be built into the bidirectional inverter 15. The intermediate link capacitor 19 is, for example, a smoothing capacitor.

[0022] The control unit 16 is configured to include at least one processor, at least one dedicated circuit, or a combination thereof. The processor is a general-purpose processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or a dedicated processor specialized for specific processing. The dedicated circuit may be, for example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The control unit 16 controls the operation of the power conditioner 10.

[0023] The control unit 16 can execute a connection sequence with the DC power supply unit 23. The connection sequence is a process of energizing the DC power supply unit 23 to the bidirectional DC / DC converter 12. It is assumed that the connection sequence is performed when the commercial grid 24 is connected to the second connection terminal 20 and the second relay 21 is ON.

[0024] The control unit 16 may start the connection sequence based on any condition. For example, the control unit 16 may start the connection sequence when the voltage detected by the first voltage sensor 14 is not zero. Furthermore, the control unit 16 may start the connection sequence when the voltage detected by the first voltage sensor 14 is not zero after sending a command to the DC power supply unit 23 to output power before the start of the connection sequence. Furthermore, for example, the control unit 16 may start the connection sequence based on detection of an operation input by a user to an input device such as a terminal device or a keyboard that detects an operation input to the power conditioner 10.

[0025] In the connection sequence, the control unit 16 causes the bidirectional inverter 15 to perform AC-DC conversion so as to output a DC voltage to the bidirectional DC / DC converter 12. After performing AC-DC conversion, the control unit 16 adjusts the DC voltage output from the bidirectional DC / DC converter 12 to the first connection terminal 11 to a first voltage. The control unit 16 may control the bidirectional inverter 15 to adjust the DC voltage to the first voltage. Alternatively, the control unit 16 may control the bidirectional DC / DC converter 12 to adjust the DC voltage to the first voltage.

[0026] The first voltage may be determined based on the output voltage of the DC power supply unit 23. For example, the first voltage may be determined arbitrarily within a predetermined range based on the output voltage. The first voltage may be set to a voltage value within the predetermined range that results in an inrush current that is small enough to prevent breakdown of the input capacitor 18, the intermediate link capacitor 19, and the switching elements of the bidirectional DC / DC converter 12. The closer the predetermined range is to the output voltage of the DC power supply unit 23, the more preferable it is, and may be, for example, a range of −50% to +20% of the output voltage. In other words, the first voltage may be set arbitrarily to a voltage value close to the output voltage, or may be set to the same value as the output voltage, whether it is higher or lower than the output voltage.

[0027] The output voltage of the DC power supply unit 23 may be acquired as information by various methods and set to a single value. The output voltage may be set based on information about the voltage actually detected by the first voltage sensor 14. As described above, in a configuration in which the voltage is actually detected, the detected voltage value may be set to the output voltage.

[0028] Alternatively, the output voltage does not have to be determined based on an actually detected value. For example, the output voltage may be determined based on information about a voltage value expected in a normal operating state of the DC power supply unit 23 connected to the power conditioner 10. Specifically, the output voltage may be determined based on information about the output voltage obtained from the DC power supply unit 23 connected to the power conditioner 10 via the communication unit 17. Alternatively, the output voltage may be determined based on information about the output voltage of the DC power supply unit 23 connected to the power conditioner 10 (e.g., information about the rated output voltage) obtained via the communication unit 17 from a server or the like of a business operator that handles the DC power supply unit 23.

[0029] In the connection sequence, the control unit 16 may set the target value for adjusting the DC voltage output from the bidirectional DC / DC converter 12 to the first connection terminal 11 to a second voltage and then change it to the first voltage. The second voltage is lower than the first voltage. Specifically, the control unit 16 may continuously increase the target value so that it passes through the second voltage and finally reaches the first voltage. Alternatively, specifically, the control unit 16 may increase the target value in stages so that it passes through at least the second voltage and finally reaches the first voltage.

[0030] The control unit 16 adjusts the DC voltage output from the bidirectional DC / DC converter 12 to the first connection terminal 11 to the first voltage, and then switches the first relay 13 ON, in other words, to a conductive state.

[0031] The control unit 16 may also include the condition for switching on the first relay 13 if the voltage detected by the first voltage sensor 14 is maintained stable. For example, the control unit 16 may switch on the first relay 13 if the DC voltage output from the bidirectional DC / DC converter 12 to the first connection terminal 11 is adjusted to the first voltage and the voltage detected by the first voltage sensor 14 is maintained stable. Specifically, in a configuration in which the DC power supply unit 23 is a solar cell, the control unit 16 may determine that the voltage is maintained stable if the fluctuation value of the voltage detected by the first voltage sensor 14 over a time range, such as 10 seconds, during a time period in which the solar radiation increases or decreases, such as in the morning or evening, falls within a range of ±1 V of the moving average value over that time range. Note that this ±1 V range is an example when the rated output of the DC power supply unit 23 is 200 V.

[0032] Even if the voltage detected by the first voltage sensor 14 is not maintained stably, the control unit 16 may switch the first relay 13 ON if the voltage is within the allowable range. For example, if the rated output of the DC power supply unit 23 is 200 V, the allowable range may be set to a range of 20 V based on the first voltage. The first voltage may be the center of the allowable range or may be different. The control unit 16 may determine that the voltage is not maintained stably if the difference between the voltage detected the first time and the voltage detected the second time 30 seconds later exceeds 20 V. Note that the case where the difference exceeds 20 V is an example when the rated output of the DC power supply unit 23 is 200 V.

[0033] The DC power supply unit 23 may include a power source 25 , a third connection terminal 26 , a third relay 27 , and a control unit 28 .

[0034] The power source 25 is capable of outputting DC power. The power source 25 is, for example, a solar cell module, a storage battery, or a fuel cell stack. The third connection terminal 26 may be electrically detachable from the first connection terminal 11. The third connection terminal 26 may be electrically connected to the power source 25 via a third relay 27. The third relay 27 may open and close the electrical connection between the power source 25 and the third connection terminal 26. The third relay 27 may, for example, interrupt current in an OFF state. The third relay 27 may, for example, conduct current in an ON state.

[0035] The control unit 28 is configured to include at least one processor, at least one dedicated circuit, or a combination thereof. The processor is a general-purpose processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or a dedicated processor specialized for specific processing. The dedicated circuit may be, for example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The control unit 28 may control the operation of the DC power supply unit 23.

[0036] The control unit 28 may switch the third relay 27 ON when receiving a command to output power from the control unit 16 of the power conditioner 10. The control unit 28 may adjust the output voltage to be output from the power source 25.

[0037] Next, the connection sequence process executed by the control unit 16 in this embodiment will be described with reference to the flowchart in FIG. 2. The connection sequence process starts, for example, when the power conditioner 10 detects the start of communication with the DC power supply unit 23. Alternatively, the connection sequence process may start when a user operation input to an input device is detected. Furthermore, for a DC power supply unit 23 that does not include the third relay 27 or a DC power supply unit 23 in which the third relay 27 is ON, the connection sequence process may start when the voltage detected by the first voltage sensor 14 is not zero or changes from zero to a value other than zero.

[0038] In step S100, the control unit 16 controls the communication unit 17 to transmit a command to output power to the DC power supply unit 23. Note that this step does not need to be executed for a DC power supply unit 23 that does not have the third relay 27. After transmitting the command to output power, the process proceeds to step S101.

[0039] In step S101, the control unit 16 determines whether the voltage detected by the first voltage sensor 14 is not zero. If the voltage is not zero, the process proceeds to step S102. If the voltage is zero, the process returns to step S101. The voltage being zero may include a voltage within a measurement error range based on the zero voltage of the first voltage sensor 14.

[0040] In step S102, the control unit 16 acquires information about the output voltage of the DC power supply unit 23 connected to the power conditioner 10. As described above, the output voltage information may be acquired from any of the first voltage sensor 14, the DC power supply unit 23, or the server. After acquiring the information, the process proceeds to step S103.

[0041] In step S103, the control unit 16 determines the first voltage based on the output voltage corresponding to the information acquired in step S102. If the information cannot be acquired in step S102, the process may wait until the information is acquired or may return to step S101. After the determination, the process proceeds to step S104.

[0042] In step S104, the control unit 16 causes the bidirectional inverter 15 to perform AC-DC conversion to supply power to the bidirectional DC / DC converter 12. The control unit 16 also causes the bidirectional DC / DC converter 12 to start voltage conversion. After the AC-DC conversion starts, the process proceeds to step S105.

[0043] In step S105, the control unit 16 adjusts the DC voltage output from the bidirectional DC / DC converter 12 to the second voltage. As described above, the control unit 16 may adjust the voltage using the bidirectional inverter 15 or the bidirectional DC / DC converter 12. After adjusting the voltage, the process proceeds to step S106.

[0044] In step S106, the control unit 16 adjusts the DC voltage output from the bidirectional DC / DC converter 12 to the first voltage. As described above, the change in the adjustment target value of the DC voltage from the second voltage to the first voltage may be continuous or may be stepwise. After the voltage adjustment, the process proceeds to step S107.

[0045] In step S107, the control unit 16 determines whether the voltage detected by the first voltage sensor 14 is maintained stable. If the voltage is not maintained stable, the process proceeds to step S108. If the voltage is maintained stable, the process proceeds to step S109.

[0046] In step S108, the control unit 16 determines whether the voltage detected by the first voltage sensor 14 is within the allowable range. If the voltage is not within the allowable range, the process proceeds to step S107. If the voltage is within the allowable range, the process proceeds to step S109.

[0047] In step S109, the control unit 16 controls the first relay 13 to be switched ON, and after the switching, the connection sequence process ends.

[0048] The power conditioner 10 of the present embodiment configured as described above includes a first connection terminal 11 for the DC power supply unit 23, a bidirectional DC / DC converter 12 connected to the first connection terminal 11, a first relay 13 that opens and closes the electrical connection between the first connection terminal 11 and the bidirectional DC / DC converter 12, a first voltage sensor 14 that detects the voltage between the first connection terminal 11 and the first relay 13, a bidirectional inverter 15 that is electrically connected to the bidirectional DC / DC converter 12, and a control unit 16 that causes the bidirectional inverter 15 to perform AC / DC conversion in a connection sequence with the DC power supply unit 23 to output a DC voltage to the bidirectional DC / DC converter 12, adjusts the DC voltage output from the bidirectional DC / DC converter 12 to the first connection terminal 11, and then switches the first relay 13 ON. With this configuration, the power conditioner 10 turns on the first relay 13 while the voltage on the bidirectional DC / DC converter 12 side of the first relay 13 is close to the output voltage of the DC power supply unit 23, thereby preventing a large inrush current from passing at the moment the first relay 13 is turned on. Therefore, the power conditioner 10 can suppress inrush current with a simple configuration without providing an inrush current prevention circuit. Furthermore, because the power conditioner 10 suppresses inrush current by executing the control method described in this embodiment, it can be configured by updating the firmware of a conventional power conditioner having a bidirectional DC / DC converter and a bidirectional inverter.

[0049] Furthermore, when the voltage detected by the first voltage sensor 14 is maintained stable, the power conditioner 10 switches the first relay 13 ON. With this configuration, even when the power conditioner 10 is connected to a DC power supply unit 23 that outputs power with a fluctuating voltage, such as a solar power generation system, the power conditioner 10 can turn on the first relay 13 when the voltage difference between the voltage on the first connection terminal 11 of the bidirectional DC / DC converter 12 and the voltage of the DC power supply unit 23 is low. Therefore, the power conditioner 10 can suppress inrush current even when the power conditioner 10 is connected to a DC power supply unit 23 that outputs power with a fluctuating voltage.

[0050] Furthermore, when the voltage detected by first voltage sensor 14 is not maintained stably, but is within an allowable range, power conditioner 10 switches on first relay 13. With this configuration, in a configuration in which power conditioner 10 is connected to DC power supply unit 23 whose output power voltage fluctuates, power conditioner 10 can prevent a large inrush current from flowing while suppressing a prolonged connection time that would be caused by a continued unstable voltage state.

[0051] Furthermore, in the power conditioner 10, the first voltage is determined based on the output voltage of the DC power supply unit 23. With this configuration, the power conditioner 10 can reduce the voltage difference between the voltage on the first connection terminal 11 side of the bidirectional DC / DC converter 12 and the voltage of the DC power supply unit 23 before the first relay 13 is connected. Therefore, the power conditioner 10 can reduce the voltage difference and thereby reduce the inrush current.

[0052] Furthermore, in the power conditioner 10, the output voltage is determined based on information about the voltage detected by the first voltage sensor 14. With this configuration, the power conditioner 10 can reduce the voltage difference with the actual voltage of the DC power supply unit 23. Therefore, the power conditioner 10 can reduce the voltage difference and thereby reduce the inrush current.

[0053] The power conditioner 10 further includes a communication unit 17 that communicates with the DC power supply unit 23, and the output voltage is determined based on output voltage information such as a rated output voltage obtained from the DC power supply unit 23. With this configuration, the power conditioner 10 can control the output voltage of the DC power supply unit 23. Therefore, the power conditioner 10 can determine a first voltage that is compatible with the specifications of the DC power supply unit 23.

[0054] The power conditioner 10 further includes a communication unit 17 for communicating information, and the output voltage is determined based on information about the output voltage of the DC power supply unit 23 acquired via the communication unit 17. With this configuration, the power conditioner 10 can acquire information about the output voltage from an external server or the like. Therefore, even if the power conditioner 10 cannot communicate with the DC power supply unit 23, the power conditioner 10 can acquire information about the rated output voltage and the like from the server of the manufacturer of the DC power supply unit 23 based on model information and the like, and determine the first voltage.

[0055] Furthermore, in the connection sequence, the power conditioner 10 sets the target value of the DC voltage output from the bidirectional DC / DC converter 12 to the first connection terminal 11 to a second voltage lower than the first voltage, and then changes the target value to the first voltage. In a configuration in which the bidirectional DC / DC converter 12 is provided with a smoothing input capacitor 18, the start of charging the input capacitor 18 at a high voltage may damage surrounding electronic components. In response to such an event, the power conditioner 10 having the above-described configuration outputs a lower DC voltage before outputting the DC voltage that is the first voltage, thereby reducing the possibility of damage to surrounding electronic components even in a configuration in which the input capacitor 18 is provided.

[0056] Furthermore, the power conditioner 10 sends a command to the DC power supply unit 23 to output power before the start of the connection sequence, and starts the connection sequence when the voltage detected by the first voltage sensor 14 is not zero. In a configuration in which the start condition of the connection sequence is that the voltage detected by the first voltage sensor 14 is not zero, the connection sequence does not start unless the DC power supply unit 23 is outputting power. In response to such an event, the power conditioner 10 having the above-described configuration can improve the reliability of the start of the connection sequence even in a configuration in which the start condition of the connection sequence is that the voltage detected by the first voltage sensor 14 is not zero.

[0057] Furthermore, the power conditioner 10 controls the bidirectional inverter 15 to adjust the DC voltage output from the bidirectional DC / DC converter 12 to the connection terminal 11 side to a first voltage. With this configuration, the power conditioner 10 adjusts the bidirectional inverter 15 to the first voltage, and can immediately adjust to the first voltage when the bidirectional DC / DC converter 12 is started, thereby improving responsiveness.

[0058] Furthermore, the power conditioner 10 controls the bidirectional DC / DC converter 12 so as to adjust the DC voltage output from the bidirectional DC / DC converter 12 to the connection terminal 11 side to the first voltage. With this configuration, the power conditioner 10 can adjust to the first voltage using the basic functions it has, without adding a dedicated control program, by adjusting to the first voltage using the bidirectional DC / DC converter 12.

[0059] In one embodiment, (1) a power conditioner includes: a connection terminal for a DC power supply unit; a bidirectional DC / DC converter connected to the connection terminal; a relay that opens and closes an electrical connection between the connection terminal and the bidirectional DC / DC converter; a voltage sensor that detects a voltage between the connection terminal and the relay; a bidirectional inverter that is electrically connected to the bidirectional DC / DC converter; and a control unit that, in a connection sequence with the DC power supply unit, causes the bidirectional inverter to perform AC / DC conversion to output a DC voltage to the bidirectional DC / DC converter side, adjusts the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage, and then switches the relay ON.

[0060] (2) In the power conditioner of (1) above, the control unit switches the relay ON when the voltage detected by the voltage sensor is maintained stable.

[0061] (3) In the power conditioner of (1) above, when the voltage detected by the voltage sensor is not maintained stably, the control unit switches the relay ON when the voltage is within an allowable range.

[0062] (4) In the power conditioner according to any one of (1) to (3) above, the first voltage is determined based on the output voltage of the DC power supply unit.

[0063] (5) In the power conditioner of (4), the output voltage is determined based on information about a voltage detected by the voltage sensor.

[0064] (6) The power conditioner of (4) above further includes a communication unit that communicates with the DC power supply unit, and the output voltage is determined based on output voltage information obtained from the DC power supply unit.

[0065] (7) The power conditioner of (4) above further includes a communication unit that communicates information, and the output voltage is determined based on information about the output voltage of the DC power supply unit obtained via the communication unit.

[0066] (8) In the power conditioner of any one of (1) to (7) above, in the connection sequence, the control unit sets a target value of the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a second voltage lower than the first voltage, and then changes the target value to the first voltage.

[0067] (9) In any of the power conditioners (1) to (8) above, the control unit sends a command to the DC power supply unit to output power before the start of the connection sequence, and starts the connection sequence when the voltage detected by the voltage sensor is not zero.

[0068] (10) In the power conditioner according to any one of (1) to (9), the control unit controls the bidirectional inverter to adjust the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage.

[0069] (11) In the power conditioner according to any one of (1) to (9), the control unit controls the bidirectional DC / DC converter so as to adjust the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage.

[0070] (12) In the power conditioner according to any one of (1) to (11), the DC power supply unit is a storage battery device, a solar power generation device, or a fuel cell device.

[0071] In one embodiment, (13) the control device includes: a control unit that, in a connection sequence between the DC power supply unit and a power conditioner having a connection terminal for a DC power supply unit, a bidirectional DC / DC converter connected to the connection terminal, a relay that opens and closes an electrical connection between the connection terminal and the bidirectional DC / DC converter, a voltage sensor that detects a voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC / DC converter, causes the bidirectional inverter to perform AC / DC conversion to output a DC voltage to the bidirectional DC / DC converter side, adjusts the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage, and then switches the relay on.

[0072] In one embodiment, (14) a power supply system includes: a DC power supply unit capable of outputting DC power; a power conditioner having a connection terminal for the DC power supply unit, a bidirectional DC / DC converter connected to the connection terminal, a relay for opening and closing an electrical connection between the connection terminal and the bidirectional DC / DC converter, a voltage sensor for detecting a voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC / DC converter; and a control device that, in a connection sequence between the power conditioner and the DC power supply unit, causes the bidirectional inverter to perform AC / DC conversion to output a DC voltage to the bidirectional DC / DC converter side, adjusts the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage, and then switches the relay ON.

[0073] The above has described an embodiment of the power conditioner 10. However, embodiments of the present disclosure can also be embodied as a method or program for implementing the device, or as a storage medium on which a program is recorded (for example, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a magnetic tape, a hard disk, or a memory card).

[0074] Furthermore, the implementation form of the program is not limited to application programs such as object code compiled by a compiler or program code executed by an interpreter, but may also be in the form of a program module incorporated into an operating system. Furthermore, the program may or may not be configured so that all processing is performed solely by the CPU on the control board. The program may also be configured so that part or all of it is executed by another processing unit mounted on an expansion board or expansion unit added to the board as needed.

[0075] The drawings illustrating the embodiments of the present disclosure are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

[0076] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art could make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included in the scope of the present disclosure. For example, the functions included in each component can be rearranged so as not to cause logical inconsistencies, and multiple components can be combined or divided into one.

[0077] For example, in the above embodiment, the control unit 16 of the power conditioner 10 executes the connection sequence, but the connection sequence may also be executed by a control device connected to the power conditioner, for example, via a network. In other words, effects similar to those of the above embodiment can be obtained in a power supply system configured with a control device capable of executing the connection sequence, together with the power conditioner and the DC power supply unit 23.

[0078] All of the features described in this disclosure and / or all steps of all of the disclosed methods or processes may be combined in any combination except combinations in which these features are mutually exclusive. Furthermore, each feature described in this disclosure may be replaced by an alternative feature serving the same, equivalent, or similar purpose, unless expressly denied. Thus, unless expressly denied, each disclosed feature is only one example of a generic series of identical or equivalent features.

[0079] Furthermore, embodiments of the present disclosure are not limited to the specific configurations of any of the above-described embodiments, but rather extend to any novel feature or combination thereof described herein, or any novel method or process step or combination thereof described herein.

[0080] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the configuration. In this disclosure, the configurations distinguished by descriptions such as "first" and "second" can have their numbers interchanged. For example, the first connection terminal can have its identifiers "first" and "second" interchanged with the second connection terminal. The identifiers are interchanged simultaneously. The configurations remain distinguished even after the identifiers are interchanged. Identifiers may be deleted. A configuration from which an identifier has been deleted is distinguished by a symbol. The identifiers "first" and "second" in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of an identifier with a smaller number.

[0081] REFERENCE SIGNS LIST 10 Power conditioner 11 First connection terminal 11a Positive terminal 11b Negative terminal 12 Bidirectional DC / DC converter 13 First relay 14 First voltage sensor 15 Bidirectional inverter 16 Control unit 17 Communication unit 18 Input capacitor 19 Intermediate link capacitor 20 Second connection terminal 21 Second relay 22 Second voltage sensor 23 DC power supply unit 24 Commercial grid 25 Power source 26 Third connection terminal 27 Third relay 28 Control unit

Claims

1. A power conditioner comprising: a connection terminal for a DC power supply unit; a bidirectional DC / DC converter connected to the connection terminal; a relay for opening and closing an electrical connection between the connection terminal and the bidirectional DC / DC converter; a voltage sensor for detecting a voltage between the connection terminal and the relay; a bidirectional inverter electrically connected to the bidirectional DC / DC converter; and a control unit for, in a connection sequence with the DC power supply unit, causing the bidirectional inverter to perform AC / DC conversion to output a DC voltage to the bidirectional DC / DC converter, and adjusting the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage, and then switching the relay ON.

2. The power conditioner according to claim 1, wherein the control unit switches the relay ON when the voltage detected by the voltage sensor is maintained stable.

3. A power conditioner according to claim 1, wherein the control unit switches the relay ON when the voltage detected by the voltage sensor is not maintained stable but is within an allowable range.

4. The power conditioner according to any one of claims 1 to 3, wherein the first voltage is determined based on the output voltage of the DC power supply unit.

5. The power conditioner according to claim 4, wherein the output voltage is determined based on information on a voltage detected by the voltage sensor.

6. A power conditioner according to claim 4, further comprising a communication unit that communicates with said DC power supply unit, and wherein said output voltage is determined based on output voltage information obtained from said DC power supply unit.

7. A power conditioner according to claim 4, further comprising a communication unit for communicating information, wherein the output voltage is determined based on information on the output voltage of the DC power supply unit acquired via the communication unit.

8. A power conditioner according to any one of claims 1 to 7, wherein, in the connection sequence, the control unit sets a target value of the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a second voltage lower than the first voltage, and then changes the target value to the first voltage.

9. A power conditioner according to any one of claims 1 to 8, wherein the control unit sends a command to the DC power supply unit to output power before the start of the connection sequence, and starts the connection sequence when the voltage detected by the voltage sensor is not zero.

10. A power conditioner according to any one of claims 1 to 9, wherein the control unit controls the bidirectional inverter so as to adjust the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage.

11. A power conditioner according to any one of claims 1 to 9, wherein the control unit controls the bidirectional DC / DC converter so as to adjust the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage.

12. The power conditioner according to any one of claims 1 to 11, wherein the DC power supply unit is a storage battery device, a solar power generation device, or a fuel cell device.

13. A control device comprising: a power conditioner having a connection terminal for a DC power supply unit, a bidirectional DC / DC converter connected to the connection terminal, a relay for opening and closing an electrical connection between the connection terminal and the bidirectional DC / DC converter, a voltage sensor for detecting a voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC / DC converter, the control device comprising: a control unit for causing the bidirectional inverter to perform AC / DC conversion to output a DC voltage to the bidirectional DC / DC converter side, adjusting the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage, and then switching the relay ON, in a connection sequence between the DC power supply unit and the power conditioner.

14. A power supply system comprising: a power conditioner having a DC power supply unit capable of outputting DC power; a connection terminal for the DC power supply unit, a bidirectional DC / DC converter connected to the connection terminal, a relay for opening and closing an electrical connection between the connection terminal and the bidirectional DC / DC converter, a voltage sensor for detecting a voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC / DC converter; and a control device for, in a connection sequence between the power conditioner and the DC power supply unit, having the bidirectional inverter perform AC / DC conversion to output a DC voltage to the bidirectional DC / DC converter side, and adjusting the DC voltage output from the bidirectional DC / DC converter to the connection terminal side to a first voltage, and then switching the relay ON.

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