JP7844762B2 - Power conditioner, control unit, and power supply system - Google Patents

Description

Cross-reference of related applications

This application claims priority to Japanese Patent Application No. 2023-203289, filed in Japan on November 30, 2023, and the entire disclosure of the earlier application is incorporated herein by reference.

This disclosure relates to power conditioners, control devices, and power supply systems.

Power conditioners are used to connect DC power supply units, such as battery storage systems and solar power generation systems, which output DC power, to power systems that carry 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. This inrush current can damage electronic components such as capacitors and coils within the power conditioner. Therefore, it has been proposed to provide an inrush current prevention circuit in the power conditioner (see Patent Document 1).

Japanese Patent Publication No. 2013-078183

From the first perspective, the power conditioner is:
Connection terminals for the DC power supply unit,
A bidirectional DC/DC converter connected to the aforementioned connection terminal,
A relay that opens and closes the electrical connection between the connection terminal and the bidirectional DC/DC converter,
A voltage sensor that detects the voltage between the connection terminal and the relay,
A bidirectional inverter electrically connected to the aforementioned bidirectional DC/DC converter,
The connection sequence with the DC power supply unit connected to the connection terminal includes a control unit that, instructing the bidirectional inverter to perform AC/DC conversion and output a DC voltage to the bidirectional DC/DC converter, adjusting the DC voltage output from the bidirectional DC/DC converter to the connection terminal to a first voltage, and then switching the relay ON.

The control device from the second perspective is:
In 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 the electrical connection between the connection terminal and the bidirectional DC/DC converter, a voltage sensor for detecting the voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC/DC converter, the power conditioner includes a control unit that 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 terminal to a first voltage, and then switches the relay ON.

From a third perspective, the power supply system is:
A DC power supply unit capable of outputting DC power,
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 the electrical connection between the connection terminal and the bidirectional DC/DC converter, a voltage sensor for detecting the voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC/DC converter,
The power conditioner includes a control device that, in the connection sequence with the DC power supply unit connected to the connection terminal , causes the bidirectional inverter to perform AC-DC conversion and output a DC voltage to the bidirectional DC/DC converter, 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.

This is a schematic diagram showing the general configuration of the power conditioner according to this embodiment. This is a flowchart illustrating the connection sequence processing performed by the control unit of the power conditioner shown in Figure 1.

Embodiments of this disclosure will be described below with reference to the drawings. In the components shown in the following drawings, the same components are denoted by the same reference numerals.

As shown in Figure 1, a power conditioner 10 according to one embodiment of the present disclosure 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 power conditioner 10 may further comprise 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.

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 connecting to the DC power supply unit 23 and is used at least for inputting the power output by the DC power supply unit 23. In a configuration where the DC power supply unit 23 is a battery storage 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, for example, a device capable of outputting DC power such as a solar power generation device, a battery storage device, or a fuel cell device. In the following description, the DC power supply unit 23 is a battery storage device. The first connection terminal 11 of the battery storage device may include a positive terminal 11a and a negative terminal 11b.

The second connection terminal 20 may be a terminal for connecting to a power system that carries AC power. The second connection terminal 20 is envisioned to be connected to, for example, a commercial power system 24.

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 the DC voltage. Specifically, the bidirectional DC/DC converter 12 outputs a DC voltage adjusted to a specific voltage value from the first connection terminal 11 side to the bidirectional inverter 15. Conversely, the bidirectional DC/DC converter 12 outputs a DC voltage adjusted to a specific voltage value from the bidirectional inverter 15 side to the first connection terminal 11 side.

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. For example, the first relay 13 may be provided 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. For example, the first relay 13 may interrupt the current in the OFF state. For example, the first relay 13 may conduct current in the ON state.

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. The second relay 21 may, for example, interrupt the current in the OFF state. The second relay 21 may, for example, conduct current in the ON state.

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

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.

The bidirectional inverter 15 may convert AC voltage to DC voltage, or DC voltage to AC voltage. In the following description, the conversion of AC voltage to DC voltage will also be referred to as AC/DC conversion. The bidirectional inverter 15 may be connected to the bidirectional DC/DC converter 12 on the DC side. Alternatively, the bidirectional inverter 15 may be connected to the second connection terminal 20 on the AC side.

The communication unit 17 may communicate information with external devices. For example, the communication unit 17 may communicate with the DC power supply unit 23. Also, the communication unit 17 may communicate with a server via a network.

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.

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 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.

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 a specific process. 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.

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

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

In the connection sequence, the control unit 16 causes the bidirectional inverter 15 to perform AC-DC conversion so that it outputs a DC voltage to the bidirectional DC/DC converter 12. After the AC-DC conversion is performed, 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 a first voltage. Alternatively, the control unit 16 may control the bidirectional DC/DC converter 12 to adjust the DC voltage to a first voltage.

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 arbitrarily determined within a predetermined range based on the output voltage. The first voltage may be set within a predetermined range such that the inrush current is such that the input capacitor 18, the intermediate link capacitor 19, and the switching elements of the bidirectional DC/DC converter 12 do not fail. The predetermined range is preferably as close as possible to the output voltage of the DC power supply unit 23, for example, a range of -50% to +20% of the output voltage. In other words, the first voltage may be arbitrarily set to a voltage value close to the output voltage, and may be set to a voltage higher or lower than the output voltage, or to the same value as the output voltage.

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

Alternatively, the output voltage does not have to be determined based on the actually detected value. For example, the output voltage may be determined based on information about the voltage value expected under normal operating conditions 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 (for example, information about the rated output voltage) obtained from a server of a business operator handling the DC power supply unit 23 via the communication unit 17.

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 a 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 becomes the first voltage. Alternatively, the control unit 16 may increase the target value in steps so that it passes through at least the second voltage and finally becomes the first voltage.

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, and then switches the first relay 13 ON, in other words, to a conductive state.

The control unit 16 may include the stable maintenance of the voltage detected by the first voltage sensor 14 as a condition for switching the first relay 13 ON. For example, the control unit 16 may switch the first relay 13 ON if it adjusts the DC voltage output from the bidirectional DC/DC converter 12 to the first connection terminal 11 to the first voltage and the voltage detected by the first voltage sensor 14 is stably maintained. As a specific example, in a configuration where the DC power supply unit 23 is a solar cell, the control unit 16 may determine that the voltage is stably maintained if, during times when sunlight changes in the upward or downward direction, such as in the morning or evening, the fluctuation value of the voltage detected by the first voltage sensor 14 over a time range, such as 10 seconds, falls within ±1V of the moving average value in that time range. Note that the ±1V range is an example where the rated output of the DC power supply unit 23 is 200V.

The control unit 16 may switch the first relay 13 ON even if the voltage detected by the first voltage sensor 14 is not maintained stably, as long as the voltage is within an acceptable range. The acceptable range may be defined as a range of 20V based on the first voltage, for example, if the rated output of the DC power supply unit 23 is 200V. The first voltage may be at the center of the acceptable 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 20V. Note that the case where the difference exceeds 20V is an example when the rated output of the DC power supply unit 23 is 200V.

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.

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 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 switch the electrical connection between the power source 25 and the third connection terminal 26. The third relay 27 may, for example, interrupt the current in the OFF state. The third relay 27 may, for example, conduct current in the ON state.

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 a specific process. 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.

When the control unit 28 receives a command from the control unit 16 of the power conditioner 10 to output power, it may switch the third relay 27 ON. The control unit 28 may adjust the output voltage output from the power source 25.

Next, the connection sequence processing performed by the control unit 16 in this embodiment will be explained using the flowchart in Figure 2. The connection sequence processing is started, for example, when the power conditioner 10 detects the start of communication with the DC power supply unit 23. Alternatively, the connection sequence processing may be started when the user detects an operation input to the input device. Furthermore, for DC power supply units 23 that do not have a third relay 27 or DC power supply units 23 in which the third relay 27 is ON, the connection sequence processing may be started when the voltage detected by the first voltage sensor 14 is not zero, or when it changes from zero to a value other than zero.

In step S100, the control unit 16 controls the communication unit 17 to send a command to the DC power supply unit 23 to output power. Note that this step does not need to be performed for DC power supply units 23 that do not have a third relay 27. After sending the power output command, the process proceeds to step S101.

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. A voltage of zero may include a voltage that is within the measurement error range with respect to zero of the first voltage sensor 14.

In step S102, the control unit 16 acquires information on 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 the first voltage sensor 14, the DC power supply unit 23, or the server. After acquiring the information, the process proceeds to step S103.

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

In step S104, the control unit 16 causes the bidirectional inverter 15 to perform AC-DC conversion and 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.

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

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

In step S107, the control unit 16 determines whether the voltage detected by the first voltage sensor 14 is being maintained stably. If it is not being maintained stably, the process proceeds to step S108. If it is being maintained stably, the process proceeds to step S109.

In step S108, the control unit 16 determines whether the voltage detected by the first voltage sensor 14 is within an acceptable range. If it is not within an acceptable range, the process proceeds to step S107. If it is within an acceptable range, the process proceeds to step S109.

In step S109, the control unit 16 controls the first relay 13 to be switched ON. After the switchover, the connection sequence processing is completed.

The power conditioner 10 of this embodiment, configured as described above, includes a first connection terminal 11 for a DC power supply unit 23, a bidirectional DC/DC converter 12 connected to the first connection terminal 11, a first relay 13 for opening and closing the electrical connection between the first connection terminal 11 and the bidirectional DC/DC converter 12, a first voltage sensor 14 for detecting the voltage between the first connection terminal 11 and the first relay 13, a bidirectional inverter 15 electrically connected to the bidirectional DC/DC converter 12, and a control unit 16 that, in the connection sequence with the DC power supply unit 23, causes the bidirectional inverter 15 to perform AC-DC conversion 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 to a first voltage, 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 flowing 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, since 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.

Furthermore, the power conditioner 10 switches the first relay 13 ON when the voltage detected by the first voltage sensor 14 is maintained stably. With this configuration, even when the power conditioner 10 is connected to a DC power supply unit 23 in which the voltage of the output power fluctuates, such as in a solar power generation system, the first relay 13 can be turned ON when 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 is low. Therefore, even when the power conditioner 10 is connected to a DC power supply unit 23 in which the voltage of the output power fluctuates, inrush current can be suppressed.

Furthermore, if the voltage detected by the first voltage sensor 14 is not maintained stably, the power conditioner 10 switches the first relay 13 ON when the voltage falls within the acceptable range. With this configuration, the power conditioner 10, in a configuration where it is connected to a DC power supply unit 23 whose output power voltage fluctuates, can prevent a prolonged connection time due to the unstable voltage while also preventing current flow due to a large inrush current.

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 connection of the first relay 13. Therefore, since the power conditioner 10 reduces this voltage difference, it can reduce the inrush current.

Furthermore, in the power conditioner 10, the output voltage is determined based on the voltage information 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, since the power conditioner 10 reduces this voltage difference, it can reduce the inrush current.

Furthermore, the power conditioner 10 is further equipped with 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 the 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 conforms to the specifications of the DC power supply unit 23.

Furthermore, the power conditioner 10 is further equipped with a communication unit 17 for communicating information, and the output voltage is determined based on the output voltage information of the DC power supply unit 23 obtained via the communication unit 17. With this configuration, the power conditioner 10 can obtain output voltage information from an external server or the like. Therefore, even if the power conditioner 10 cannot communicate with the DC power supply unit 23, it can obtain information such as the rated output voltage from the manufacturer's server of the DC power supply unit 23 based on model information, etc., and determine the first voltage.

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 it to the first voltage. In a configuration in which a smoothing input capacitor 18 is provided in the bidirectional DC/DC converter 12, the high voltage at which the input capacitor 18 is charged may damage surrounding electronic components. To address this issue, the power conditioner 10 having the above configuration outputs a lower DC voltage before outputting the first DC voltage, thereby reducing the possibility of damage to surrounding electronic components even in a configuration in which an input capacitor 18 is provided.

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 if the voltage detected by the first voltage sensor 14 is not zero. In a configuration where the start condition of the connection sequence is that the voltage detected by the first voltage sensor 14 is not zero, the connection sequence will not start if the DC power supply unit 23 is not outputting power. In response to such events, the power conditioner 10 having the above configuration can improve the reliability of starting the connection sequence, even in a configuration where the start condition of the connection sequence is that the voltage detected by the first voltage sensor 14 is not zero.

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 to a first voltage. With this configuration, the power conditioner 10 can adjust to the first voltage immediately when the bidirectional DC/DC converter 12 is started by adjusting the bidirectional inverter 15 to the first voltage, thereby improving responsiveness.

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 to a first voltage. With this configuration, the power conditioner 10 can adjust to a first voltage using its basic functions without adding a dedicated control program, by adjusting the bidirectional DC/DC converter 12 to obtain the first voltage.

In one embodiment, (1) the power conditioner is
Connection terminals for the DC power supply unit,
A bidirectional DC/DC converter connected to the aforementioned connection terminal,
A relay that opens and closes the electrical connection between the connection terminal and the bidirectional DC/DC converter,
A voltage sensor that detects the voltage between the connection terminal and the relay,
A bidirectional inverter electrically connected to the aforementioned bidirectional DC/DC converter,
The connection sequence with the DC power supply unit includes a control unit that causes the bidirectional inverter to perform AC/DC conversion and output a DC voltage to the bidirectional DC/DC converter, 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.

(2) In the power conditioner described in (1) above,
The control unit switches the relay ON when the voltage detected by the voltage sensor is maintained stably.

(3) In the power conditioner described in (1) above,
If the voltage detected by the voltage sensor is not maintained stably, the control unit switches the relay ON when the voltage falls within an acceptable range.

(4) In any of the power conditioners described in (1) to (3) above,
The first voltage is determined based on the output voltage of the DC power supply unit.

(5) The power conditioner in (4) above is
The output voltage is determined based on the voltage information detected by the voltage sensor.

(6) The power conditioner in (4) above is
The unit further comprises a communication unit that communicates with the aforementioned DC power supply unit,
The output voltage is determined based on the output voltage information obtained from the DC power supply unit.

(7) The power conditioner in (4) above is
It is further equipped with a communication unit for transmitting information,
The output voltage is determined based on the output voltage information of the DC power supply unit obtained via the communication unit.

(8) In any of the power conditioners described in (1) through (7) above,
In the connection sequence, the control unit sets the target value of the DC voltage output from the bidirectional DC/DC converter to the connection terminal to a second voltage lower than the first voltage, and then changes it to the first voltage.

(9) In any of the power conditioners described in (1) through (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 if the voltage detected by the voltage sensor is not zero.

(10) In any of the power conditioners described in (1) through (9) above,
The control unit controls the bidirectional inverter to adjust the DC voltage output from the bidirectional DC/DC converter to the connection terminal to a first voltage.

(11) In any of the power conditioners described in (1) through (9) above,
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) In any of the power conditioners described in (1) through (11) above,
The DC power supply unit is a battery storage device, a solar power generation device, or a fuel cell device.

In one embodiment, (13) the control device is
In a connection sequence between 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 the electrical connection between the connection terminal and the bidirectional DC/DC converter, a voltage sensor for detecting the voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC/DC converter, the power conditioner includes a control unit that 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 terminal to a first voltage, and then switches the relay ON.

In one embodiment, (14) the power supply system is
A DC power supply unit capable of outputting DC power,
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 the electrical connection between the connection terminal and the bidirectional DC/DC converter, a voltage sensor for detecting the voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC/DC converter,
The connection sequence between the power conditioner and the DC power supply unit includes a control device that causes the bidirectional inverter to perform AC-DC conversion and output a DC voltage to the bidirectional DC/DC converter, 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.

While embodiments of the power conditioner 10 have been described above, embodiments of the power conditioner 10 can also be provided as a storage medium on which a program is recorded, in addition to a method or program for implementing the device.

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 embedded in an operating system. Moreover, the program may or may not be configured so that all processing is performed only on the CPU on the control board. The program may also be configured so that some or all of its processing is performed by another processing unit implemented on an expansion board or expansion unit attached to the board, as needed.

The diagrams illustrating the embodiments described herein are schematic. Dimensions and proportions shown in the drawings do not necessarily correspond to actual dimensions.

While embodiments relating to this disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can make various modifications or alterations based on this disclosure. Therefore, it should be noted that these modifications or alterations are within the scope of this disclosure. For example, the functions included in each component can be rearranged in a logically consistent manner, and multiple components can be combined into one or separated.

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

All of the constituent elements described in this disclosure, and/or all of the methods or steps of the processes disclosed, can be combined in any combination except for any combination in which these features are mutually exclusive. Furthermore, each of the features described in this disclosure can be replaced by an alternative feature that works for the same, equivalent, or similar purposes, unless expressly disregarded. Thus, unless expressly disregarded, each of the disclosed features is merely an example of a comprehensive set of identical or equivalent features.

Furthermore, the embodiments relating to this disclosure are not limited to any specific configuration of the embodiments described above. The embodiments relating to this disclosure can be extended to all novel features or combinations thereof described herein, or all novel methods or processing steps or combinations thereof described herein.

In this disclosure, the terms "First," "Second," etc., are identifiers used to distinguish the configurations. Configurations distinguished by the terms "First," "Second," etc., in this disclosure may have their numbers swapped. For example, the first connector and the second connector may have their identifiers "First" and "Second" swapped. The identifier swapping occurs simultaneously. The configurations remain distinguishable even after the identifier swapping. Identifiers may be deleted. Configurations from which identifiers have been deleted are distinguished by their codes. The terms "First," "Second," etc., in this disclosure should not be used alone to interpret the order of the configurations or to justify the existence of smaller numbered identifiers.

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 (14)

Connection terminals for the DC power supply unit,
A bidirectional DC/DC converter connected to the aforementioned connection terminal,
A relay that opens and closes the electrical connection between the connection terminal and the bidirectional DC/DC converter,
A voltage sensor that detects the voltage between the connection terminal and the relay,
A bidirectional inverter electrically connected to the aforementioned bidirectional DC/DC converter,
A power conditioner comprising: a control unit that, in a connection sequence with a DC power supply unit connected to the connection terminal , causes the bidirectional inverter to perform AC-DC conversion and 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. In the power conditioner according to claim 1,
The control unit switches the relay ON when the voltage detected by the voltage sensor is maintained stably. In the power conditioner according to claim 1,
The control unit switches the relay ON when the voltage detected by the voltage sensor is not maintained stably, and when the voltage is within an acceptable range. In the power conditioner according to any one of claims 1 to 3,
The first voltage is determined based on the output voltage of the DC power supply unit. In the power conditioner according to claim 4,
The output voltage is determined based on the voltage information detected by the voltage sensor. In the power conditioner according to claim 4,
The unit further comprises a communication unit that communicates with the aforementioned DC power supply unit,
The output voltage is determined based on the output voltage information obtained from the DC power supply unit. In the power conditioner according to claim 4,
It is further equipped with a communication unit for transmitting information,
The output voltage is determined based on the output voltage information of the DC power supply unit obtained via the communication unit. In the power conditioner according to any one of claims 1 to 3,
The control unit, in the connection sequence, sets the target value of the DC voltage output from the bidirectional DC/DC converter to the connection terminal to a second voltage lower than the first voltage, and then changes it to the first voltage. In the power conditioner according to any one of claims 1 to 3,
The control unit sends a command to the DC power supply unit to output power before the start of the connection sequence, and the power conditioner starts the connection sequence if the voltage detected by the voltage sensor is not zero. In the power conditioner according to any one of claims 1 to 3,
The control unit is a power conditioner that 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. In the power conditioner according to any one of claims 1 to 3,
The control unit is a power conditioner that 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. In the power conditioner according to any one of claims 1 to 3,
The DC power supply unit is a power conditioner which is a battery storage device, a solar power generation device, or a fuel cell device. A control device comprising a control unit that, in a connection sequence with a DC power supply unit connected to a connection terminal in 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 the electrical connection between the connection terminal and the bidirectional DC/DC converter, a voltage sensor for detecting the voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC/DC converter, the control unit that 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 terminal to a first voltage, and then switches the relay ON. A DC power supply unit capable of outputting DC power,
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 the electrical connection between the connection terminal and the bidirectional DC/DC converter, a voltage sensor for detecting the voltage between the connection terminal and the relay, and a bidirectional inverter electrically connected to the bidirectional DC/DC converter,
A power supply system comprising: a control device that, in the connection sequence between the power conditioner and the DC power supply unit connected to the connection terminal , causes the bidirectional inverter to perform AC-DC conversion and output a DC voltage to the bidirectional DC/DC converter, 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.