JP7809985B2 - Charge/discharge control device, program, and charge/discharge control method - Google Patents

Description

The present invention relates to a charge/discharge control device, a program, and a charge/discharge control method.

Conventionally, in the technical field of controlling the distribution of electricity generated by a solar power generation system installed in a house, a technique is known in which surplus electricity shared among loads in the house is controlled to be supplied to an on-board storage battery installed in a vehicle (see, for example, Patent Document 1).
Furthermore, there is known a technology for supplying power stored in an on-board storage battery to loads in a home during nighttime or other times when power cannot be obtained from solar power generation. One such technology, in particular, sets a lower limit value for the State of Charge (SOC) and controls the SOC of the on-board storage battery so that it does not fall below the set lower limit value (see, for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 2020-031484 Japanese Patent Application Laid-Open No. 2020-018120

When using the above-mentioned technology, setting the SOC lower limit low widens the SOC range in which the battery can be charged and discharged, but there is a problem in that the vehicle cannot be driven long distances when the vehicle is in a low SOC state. Setting the SOC lower limit high also ensures an SOC that allows long distance driving, but narrows the SOC range in which the battery can be charged and discharged. Frequent changes to the SOC lower limit also complicate operations, impairing usability. In other words, with conventional technology, it has been difficult to combine mobility and storage battery applications for vehicles equipped with on-board storage batteries.

The present invention aims to provide optimal control so that a vehicle equipped with an on-board storage battery can be used for both mobility and storage battery purposes.

An inverter charge/discharge control device according to one embodiment of the present invention is a charge/discharge control device that controls charging of an on-board storage battery from a DC power source and discharging from the on-board storage battery to a load, and includes: a target SOC acquisition unit that acquires a target SOC indicating the SOC of the on-board storage battery at a target time; a target time acquisition unit that acquires the target time; a calculation unit that calculates a charging start time , which is the time to start charging the on-board storage battery, at predetermined regular time intervals based on the target SOC and the target time so that charging is completed by the target time; a current time acquisition unit that acquires the current time; and a control unit that compares the acquired current time with the calculated charging start time, controls to start charging when the charging start time has arrived, and controls to stop charging when it is determined that the SOC of the on-board storage battery has reached the target SOC.

In addition, a charge/discharge control device according to one aspect of the present invention further includes an SOC lower limit value acquisition unit that acquires a lower limit value of the SOC of the on-board storage battery when discharging from the on-board storage battery to a load, and the control unit controls the discharge from the on-board storage battery to the load, and when the SOC of the on-board storage battery reaches the lower limit value, controls the discharge from the on-board storage battery to the load to be stopped.

In a charge/discharge control device according to one aspect of the present invention, the calculation unit calculates the charge start time based on the difference between the current SOC of the on-board storage battery and the target SOC, and the charging power, which is the rate at which the on-board storage battery is charged.

In a charge/discharge control device according to one aspect of the present invention, the charging power is a constant value, and the calculation unit calculates the charging start time based on the predetermined charging power.

In a charge/discharge control device according to one aspect of the present invention, the calculation unit learns the charging power based on the charging time and charge amount required to charge the on-board storage battery, and calculates the charging start time based on the learned charging power.

In addition, a charge/discharge control device according to one aspect of the present invention further includes a notification unit that notifies whether the charging power calculated by the calculation unit is equal to or less than a predetermined rated charging power.

In addition, a charge/discharge control device according to one aspect of the present invention further includes a charge priority time slot acquisition unit that acquires a charge priority time slot, and the control unit controls the device to start charging during the acquired charge priority time slot regardless of the charge start time.

In addition, in a charge/discharge control device according to one aspect of the present invention, the DC power source is a solar cell that converts light energy into DC power, and the control unit determines the direction of power flow based on sensor output information acquired by a current sensor that acquires information about the power supplied from the grid power to the load or the power supplied from the DC power source to the grid power.

In addition, in a charge/discharge control device according to one aspect of the present invention, the control unit prioritizes charging from the solar cell to the on-board storage battery when the charge priority time period is not in progress, the charge start time has not yet been reached, and the direction of the power flow indicated in the sensor output information is a reverse power flow to the grid power, and prioritizes discharging of the on-board storage battery when the charge priority time period is not in progress, the charge start time has not yet been reached, and the direction of the power flow indicated in the sensor output information is a forward power flow from the grid power.

Furthermore, a program according to one aspect of the present invention causes a computer that controls charging of an on-board storage battery from a DC power supply and discharging of the on-board storage battery to a load to execute the following steps: a target SOC acquisition step of acquiring a target SOC indicating the SOC of the on-board storage battery at a target time; a target time acquisition step of acquiring the target time; a calculation step of calculating a charging start time , which is the time to start charging the on-board storage battery, at predetermined regular time intervals based on the target SOC and the target time so that charging is completed by the target time; a current time acquisition step of acquiring a current time; and a control step of comparing the acquired current time with the calculated charging start time, and controlling to start charging when the charging start time has arrived, and controlling to stop charging when it is determined that the SOC of the on-board storage battery has reached the target SOC.

Furthermore, a charge/discharge control method according to one aspect of the present invention is a charge/discharge control method for controlling charging of an on-board storage battery from a DC power source and discharging from the on-board storage battery to a load, and includes a target SOC acquisition step for acquiring a target SOC indicating the SOC of the on-board storage battery at a target time; a target time acquisition step for acquiring the target time; a calculation step for calculating a charge start time , which is the time to start charging the on-board storage battery, at predetermined regular time intervals based on the target SOC and the target time so that charging is completed by the target time; a current time acquisition step for acquiring a current time; and a control step for comparing the acquired current time with the calculated charge start time, and controlling to start charging when the charge start time has arrived, and controlling to stop charging when it is determined that the SOC of the on-board storage battery has reached the target SOC.

This invention makes it possible for vehicles equipped with on-board storage batteries to be used for both mobility and storage battery purposes.

1 is a diagram showing an overview of a charge/discharge system according to a first embodiment; 3A and 3B are diagrams for explaining an example of the operation of the charge/discharge control device according to the first embodiment. FIG. 2 is a diagram illustrating an example of a functional configuration of the charge/discharge control device according to the first embodiment. FIG. 10 is a diagram illustrating an example of a user request acquisition screen according to the first embodiment. 4 is a flowchart showing an example of the operation of the charge/discharge control device according to the first embodiment. 5A and 5B are diagrams for explaining the relationship between a target time and a charge/discharge operation according to the first embodiment. FIG. 4 is a diagram illustrating an example of the relationship between PV power generation amount, V2H charge/discharge amount, and home power consumption amount according to the first embodiment. FIG. 10 is a diagram illustrating an example of a functional configuration of a charge/discharge control device according to a second embodiment. FIG. 11 is a diagram illustrating an example of a user request acquisition screen according to the second embodiment. FIG. 10 is a diagram illustrating an example of a functional configuration of a charge/discharge control device according to a third embodiment. FIG. 10 is a diagram illustrating an example of a functional configuration of a charge/discharge control device according to a fourth embodiment. FIG. 13 is a diagram illustrating an example of a user request acquisition screen according to the fourth embodiment.

Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention can be applied are not limited to the following embodiments.

[First embodiment]
First, the first embodiment will be described with reference to FIGS.
1 is a diagram showing an outline of a charge/discharge system according to a first embodiment. The outline of the charge/discharge system 1 will be described with reference to the diagram.
The charge/discharge system 1 includes a charge/discharge control device 10, a house 20, a vehicle 31, a storage battery 41, and a grid power 62. The house 20 includes a solar panel 21 and a load 57. The charge/discharge system 1 supplies power generated by the solar panel 21 to at least one of the load 57, the storage battery 41, and the vehicle 31. The charge/discharge system 1 also supplies power from the grid power 62 to at least one of the load 57 and the vehicle 31. The charge/discharge system 1 also supplies power from at least one of the vehicle 31 and the storage battery 41 to the load 57.

The solar panel 21 is connected to the charge/discharge control device 10 via a connection box 22 .
The solar panel 21 is configured to include a plurality of cells. Each of the plurality of cells converts sunlight emitted from the sun into DC power. The solar panel 21 supplies the converted DC power to at least one of the load 57, the grid power 62, the storage battery 41, and the vehicle 31 via the connection box 22. In other words, the solar panel 21 is a DC power source that converts light energy such as sunlight into DC power and supplies the converted DC power. In the following description, the solar panel 21 may also be referred to as a solar cell.

The solar panel 21 may be any current source capable of supplying power, and other renewable energy sources such as wind power, hydroelectric power, and geothermal power may be used instead of the solar panel 21.

The storage battery 41 stores the power supplied from the solar panel 21 and discharges the stored power to the load 57 .
The amount of power generated by the solar panel 21 is greatly affected by the weather of the day. Therefore, the charging/discharging system 1 stores and discharges power by including a storage battery 41 in addition to the solar panel 21. The storage battery 41 stores surplus power generated by the solar panel 21 and discharges it to the load 57 when the output from the solar panel 21 is low or during the nighttime hours, etc. The charging/discharging system 1 includes the storage battery 41 to prevent a drop in the voltage supplied to the load 57.

The vehicle 31 includes an on-board storage battery 311. The on-board storage battery 311 stores DC power. The vehicle 31 runs using the DC power stored in the on-board storage battery 311 as an energy source. That is, the vehicle 31 may be an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV).
Specifically, the on-board storage battery 311 stores the power generated by the solar panel 21 via the DC link V2H32. The on-board storage battery 311 also stores the power supplied from the grid power 62 via the DC link V2H32.

During times when the vehicle 31 is not being used as a vehicle, the on-board storage battery 311 functions in the same way as the storage battery 41. That is, the on-board storage battery 311 stores surplus electricity generated by the solar panel 21, and discharges it to the load 57 when the output from the solar panel 21 is low or during the nighttime hours, etc.

The house 20 includes a grid-connected breaker 51 , a switching box 52 , an audio monitor 53 , a distribution board 54 , a current sensor 55 , a router 56 , and a load 57 .
The grid-connection breaker 51 is used to connect the solar panels 21 to the distribution board 54. The grid-connection breaker 51 is also used to connect the grid power 62 to the distribution board 54 via the smart meter 61. The switching box 52 switches between a grid-connected state and an independent operation state. The audio monitor 53 displays the amount of power generated by the solar panels 21 and the amount of power used by the house 20, and provides audio guidance. The distribution board 54 distributes power to the loads 57. The distribution board 54 has a function as a ground fault breaker that cuts off power if a ground fault occurs in any of the loads. The current sensor 55 acquires information about the power supplied from the grid power 62 to the load 57 or the power supplied from the solar panels 21 to the grid power 62. In other words, the direction of power flow can be determined based on the sensor output information of the current sensor 55.

The router 56 is connected to a mobile terminal device 71 via a specified communication network NW. The mobile terminal device 71 may be an electronic device such as a smartphone or tablet. The router 56 communicates with the audio monitor 53, storage battery 41, and DC link V2H32 via the charge/discharge control device 10. By providing these communication networks, the charge/discharge system 1 can operate the charge/discharge control settings from the mobile terminal device 71.

The load 57 specifically includes a 100V load 571 and a 200V load 572. The 100V load 571 is a load driven by 100V AC. Examples of the 100V load 571 include a refrigerator, washing machine, television, air conditioner, and light bulb. The 200V load 572 is a load driven by 200V AC. Examples of the 200V load 572 include an air conditioner and an induction cooker.

Figure 2 is a diagram illustrating an example of the operation of the charge/discharge control device according to the first embodiment. An example of the operation of the charge/discharge control device 10 will be described with reference to the diagram. The charge/discharge control device 10 monitors the power flow using a current sensor 55. If the power flow is a reverse flow toward the grid power, it determines that there is surplus solar-generated power, and charges the on-board storage battery 311. If the power flow is a forward flow from the grid power, it determines that there is insufficient solar-generated power for the in-house load, and discharges power from the on-board storage battery 311 to the in-house distribution board 54.

The power supply changeover switch 11 includes a normal terminal 111, an independent terminal 112, and a load side terminal 113. The power supply changeover switch 11 switches the connection between either the normal terminal 111 and the load side terminal 113 or the independent terminal 112 and the load side terminal 113.
The load side terminal 113 is connected to the distribution board 54. The load side terminal 113 is also connected to the solar panel 21 via a power conditioner (PV power conditioner) 23.

The normal terminal 111 is connected to the grid power 62 via a main breaker 63. A current sensor 55 is connected between the power supply changeover switch 11 and the main breaker 63. The current sensor 55 detects the current flowing between the main breaker 63 and the power supply changeover switch 11.
When the power supply changeover switch 11 establishes electrical continuity between the normal terminal 111 and the load side terminal 113 , power is supplied from the grid power 62 to the load 57 , or power is supplied from the solar panel 21 to the grid power 62 .

The self-sustaining terminal 112 is connected to the AC link type V2H 33. The AC link type V2H 33 is connected to the in-vehicle storage battery 311.
When the power supply changeover switch 11 establishes electrical continuity between the independent terminal 112 and the load side terminal 113 , power is supplied from the vehicle storage battery 311 to the load 57 , or power is supplied from the solar panel 21 to the vehicle storage battery 311 .

3 is a diagram showing an example of the functional configuration of the charge/discharge control device according to the first embodiment. An example of the functional configuration of the charge/discharge control device 10 will be described with reference to the diagram. The charge/discharge control device 10 includes a target SOC acquisition unit 110, a target time acquisition unit 120, a calculation unit 130, a current time acquisition unit 140, and a control unit 150.
The charge/discharge control device 10 may be included inside the AC link type V2H 33.

When the vehicle 31 is used for mobility purposes, it is desirable that the SOC (State Of Charge) of the on-board storage battery 311 be equal to or greater than a predetermined value when the user uses the vehicle 31 for mobility purposes (i.e., when the user gets into the vehicle 31). In other words, it is desirable that the SOC of the on-board storage battery 311 be equal to or greater than the target SOC at the target time. Therefore, the charge/discharge control device 10 acquires the target time and target SOC from the user and controls the charging/discharging of the on-board storage battery 311 so that the SOC is equal to or greater than the target SOC at the target time. Specifically, if the target time is 7:00 and the target SOC is 70%, the charge/discharge control device 10 controls the charging/discharging of the on-board storage battery 311 so that the SOC of the on-board storage battery 311 is equal to or greater than 70% at 7:00 every day.

Note that the target time indicates the time when the user plans to start using the vehicle 31 for mobility purposes, and the target SOC is a value indicating the target value of the SOC of the on-board storage battery 311 at the target time.

The target SOC acquisition unit 110 acquires the target SOC. The target time acquisition unit 120 acquires the target time. Information including the target SOC is also referred to as target SOC information IS. Information including the target time is also referred to as target time information IT. The target SOC acquisition unit 110 outputs the target SOC information IS to the calculation unit 130. The target time acquisition unit 120 outputs the target time information IT to the calculation unit 130.

Figure 4 is a diagram showing an example of a user request acquisition screen according to the first embodiment. An example of the user request acquisition screen D10 will be described with reference to the same figure. The charge/discharge control device 10 uses the user request acquisition screen D10 to acquire the target SOC and target time from the user. The user request acquisition screen D10 may be displayed on a display unit (not shown) provided in the charge/discharge control device 10, or on a display unit of another device such as a mobile terminal device 71.

The user request acquisition screen D10 has a text box D11 and a text box D12 as screen components. The user enters information in a predetermined manner in the text box D11 to acquire the target SOC. The user enters information in a predetermined manner in the text box D12 to acquire the target time.

For example, the user inputs the target SOC and target time using an input device such as a keyboard or a voice input device such as a microphone. The user request acquisition screen D10 also displays a predetermined set of options, allowing the user to input the target SOC and target time by selecting the desired target SOC and target time from the displayed options.

3 , calculation unit 130 acquires target SOC information IS from target SOC acquisition unit 110 and acquires target time information IT from target time acquisition unit 120. Calculation unit 130 calculates the charging start time based on the target SOC included in the acquired target SOC information IS and the target time included in the target time information IT.
The charging start time is the time when charging of the in-vehicle storage battery 311 starts. Information including the charging start time is also referred to as charging start time information IST. The calculation unit 130 outputs the charging start time information IST to the control unit 150.

The current time acquisition unit 140 acquires the current time. Information including the current time is also referred to as current time information RT. The current time acquisition unit 140 outputs the current time information RT to the control unit 150.

The control unit 150 acquires charging start time information IST from the calculation unit 130 and acquires current time information RT from the current time acquisition unit 140. The control unit 150 compares the current time included in the acquired current time information RT with the charging start time included in the charging start time information IST, and when the charging start time arrives, controls the initiation of charging of the on-board storage battery 311 from the solar panel 21 or grid power 62. The control unit 150 also acquires information related to the current SOC of the on-board storage battery 311 and compares the current SOC with the target SOC. When the control unit 150 determines that the current SOC of the on-board storage battery 311 has reached the target SOC, it controls the initiation of charging.

Figure 5 is a flowchart showing an example of the operation of the charge/discharge control device according to the first embodiment. An example of the operation of the charge/discharge control device 10 will be described with reference to this figure.

(Step S110) The user sets the "daytime electricity rate time zone" and "nighttime electricity rate time zone" using a predetermined method. Based on the user's settings, the charge/discharge control device 10 obtains information about the "daytime electricity rate time zone" and "nighttime electricity rate time zone."

The "daytime electricity rate time period" is a time period in which the daytime electricity rate is applied when purchasing electricity from the grid power 62.
The "nighttime electricity rate time period" is a time period in which the nighttime electricity rate applies when purchasing electricity from the grid power 62.
Generally, electricity rates differ between "daytime electricity rate time zones" and "nighttime electricity rate time zones." In particular, electricity rates are lower during "nighttime electricity rate time zones," when electricity usage is low, than during "daytime electricity rate time zones."

(Step S120) The user sets the "target SOC" and "target time" using a predetermined method. Based on the user's settings, the charge/discharge control device 10 acquires information about the "target SOC" and "target time." Specifically, the target SOC acquisition unit 110 acquires target SOC information IS, and the target time acquisition unit 120 acquires target time information IT.

Note that the operation shown in step S110 may be performed less frequently than the operation shown in step S120. For example, in a user interface operated by a user, the setting items shown in step S110 are located at a deeper level than the setting items shown in step S120. This configuration allows the user to set the setting items shown in step S120 more easily than the setting items shown in step S110.

(Step S130) The calculation unit 130 calculates the charging start time based on the "target time" and "target SOC" acquired in step S120. Specifically, the charge/discharge control device 10 acquires the "current SOC," which is the current SOC of the on-board storage battery 311, and calculates the charging start time from the "target time," "current SOC," "target SOC," and "rated charging power." The "rated charging power" is a value determined according to the on-board storage battery 311 and may be stored in advance by the charge/discharge control device 10.

The charging start time may be calculated at predetermined intervals, such as three hours or one hour.
Furthermore, the calculation unit 130 may calculate the charging start time at predetermined regular time intervals, and may also calculate the time when the vehicle 31 is reconnected to the DC link V2H32.

The calculation unit 130 may further calculate the charging start time based on the charging power [kW], which is the rate at which the in-vehicle storage battery 311 is charged.
When the calculation unit 130 calculates the charging start time based on the charging rate, the calculation unit 130 calculates the charging start time based on the difference between the current SOC and the target SOC of the in-vehicle storage battery 311 and the charging power.

Here, the charging power may be a predetermined constant value. If the charging power is a predetermined constant value, the calculation unit 130 calculates the charging start time based on the predetermined charging power.

As a modified example, the charge/discharge control device 10 may be configured to learn the charging power. In this case, the charge/discharge control device 10 learns the charging power using a machine learning algorithm. The machine learning algorithm may learn the charging power through supervised learning using the charging time and the charge amount required to charge the in-vehicle storage battery 311 as training data. The machine learning algorithm may be included in the calculation unit 130.
In other words, the calculation unit 130 learns the charging power based on the charging time and charge amount required to charge the in-vehicle storage battery 311, and calculates the charging start time based on the learned charging power.

(Step S140) The control unit 150 determines whether the charging start time calculated in step S130 has arrived. If the control unit 150 determines that the charging start time has arrived (i.e., step S140; YES), the process proceeds to step S150. If the control unit 150 determines that the charging start time has not arrived (i.e., step S140; NO), the process proceeds to step S160.

(Step S150) The charge/discharge control device 10 charges the in-vehicle storage battery 311 with the rated charging power. The charge/discharge control device 10 stops charging when the in-vehicle storage battery 311 reaches the "target SOC."
In addition, if there is electricity generated by the solar panel 21 that cannot be consumed by the load 57, the charge/discharge control device 10 may charge the on-board storage battery 311 even if the electricity exceeds the ``target SOC.''
The charge/discharge control device 10 proceeds to step S130.

In the following description, power generated by the solar panel 21 that cannot be consumed by the load 57 may also be referred to as "PV surplus." Furthermore, when a PV surplus occurs, the surplus power may also be referred to as "PV surplus."
In addition, even if the power generated by the solar panel 21 is used, the case where the power consumed by the load 57 is insufficient may also be referred to as a "PV shortage." In addition, when a PV shortage occurs, the insufficient power may also be referred to as a "PV shortage."

(Step S160) The control unit 150 determines whether or not it is within the daytime rate time zone based on the current time acquired by the current time acquisition unit 140. If the control unit 150 determines that it is within the daytime rate time zone (i.e., step S160; YES), the control unit 150 proceeds to step S170. If the control unit 150 determines that it is not within the daytime rate time zone (i.e., step S160; NO), the control unit 150 proceeds to step S180.

(Step S170) Until the start of the "nighttime electricity rate period," the charge/discharge control device 10 monitors the power flow within the house from the sensor output information of the current sensor 55. Specifically, the control unit 150 determines the direction of the power flow based on the sensor output information acquired by the current sensor 55.
When there is a PV surplus, the charge/discharge control device 10 charges the in-vehicle storage battery 311. Furthermore, when the power consumption of the load 57 exceeds the power generated by the solar panel 21 (i.e., when there is a PV deficiency), the charge/discharge control device 10 discharges the in-vehicle storage battery 311 to the load 57.
The charge/discharge control device 10 proceeds to step S130.

(Step S180) The charge/discharge control device 10 charges the on-board storage battery 311 at the rated power. When the SOC of the on-board storage battery 311 reaches the "target SOC", the charge/discharge control device 10 stops charging the on-board storage battery 311. When charging the on-board storage battery 311, the charge/discharge control device 10 uses the PV surplus if there is a PV surplus, and charges from the grid power 62 if there is no PV surplus.
The charge/discharge control device 10 proceeds to step S130.

6 is a diagram for explaining the relationship between the target time and the charge/discharge operation according to the first embodiment. The relationship between the target time and the charge/discharge operation will be explained with reference to the diagram.
In the figure, the horizontal axis represents time, and the operation of the charge/discharge control device 10 is shown in the morning, afternoon, evening, and late night. The electricity rates in the morning, afternoon, and evening are daytime rates, and the electricity rate in the late night is nighttime rates. As an example, the figure shows the operation over two days when the target SOC and target time are set on the morning of the first day. The figure also shows the operation when the target time is set in the morning and when it is set from afternoon to night.

First, an example in which the target time is set to morning will be described.
At time t1, the user sets a target SOC and a target time. Specifically, the target SOC acquisition unit 110 acquires target SOC information IS, and the target time acquisition unit 120 acquires target time information IT.
The calculation unit 130 calculates the charging start time based on the acquired target SOC acquisition unit 110 and target SOC information IS.
The control unit 150 compares the calculated charging start time with the current time acquired by the current time acquisition unit 140, and determines whether the charging start time has arrived.

During the time period up to time t4, the charge/discharge control device 10 charges the in-vehicle storage battery 311 if there is a PV surplus.
Furthermore, during the period up to time t4, the user may or may not use the vehicle 31 for mobility purposes. When the user uses the vehicle 31 for mobility purposes, the on-board storage battery 311 is again connected to the charge/discharge control device 10 in a state where the remaining SOC decreases with use. If there is a PV surplus, the charge/discharge control device 10 charges the on-board storage battery 311.

At time t4, the control unit 150 determines that it is time to start charging. As it is time to start charging, the control unit 150 starts charging the onboard storage battery 311. This time period is a nighttime rate period (i.e., electricity rates are low), but the control unit 150 does not necessarily charge the onboard storage battery 311 until its SOC reaches 100%, but charges it up to the target SOC. By not charging the onboard storage battery 311 until its SOC reaches 100%, the charge/discharge control device 10 ensures a fatigue area where charging is performed using surplus PV.

At time t5, which is the target time, the SOC of the on-board storage battery 311 reaches the target SOC. From then on, if there is a PV surplus, the charge/discharge control device 10 charges the on-board storage battery 311.

In the period up to time t8, the user may or may not use the vehicle 31 for mobility purposes. If the user uses the vehicle 31 for mobility purposes, the on-board storage battery 311 is again connected to the charge/discharge control device 10 when the remaining SOC decreases due to use. If there is a PV surplus, the charge/discharge control device 10 charges the on-board storage battery 311.

At time t8, the control unit 150 again determines that the charging start time has arrived. Because the charging start time has arrived, the control unit 150 starts charging the in-vehicle storage battery 311. Thereafter, the same processing as on the first day is repeated.

Next, we will explain an example of when the target time is set from noon to night. In this example of when the target time is set to late at night, we may omit explanations of the content already explained in the example of when the target time is set to morning.

At time t2, the control unit 150 determines that the charging start time has arrived. Because the charging start time has arrived, the control unit 150 starts charging the onboard storage battery 311. This time period is a daytime rate period (i.e., electricity rates are high). Therefore, the control unit 150 charges the onboard storage battery 311 with power generated by the solar panel 21 if possible, and if there is a PV shortage, charges the onboard storage battery 311 from grid power 62.

Specifically, the charge/discharge control device 10 monitors the current flow within the house 20 using a current sensor 55, and if there is a PV surplus, it charges the on-board storage battery 311 with power generated by the solar panel 21. If there is a PV shortage, it charges the on-board storage battery 311 from grid power 62.

At time t3, which is the target time, the SOC of the on-board storage battery 311 reaches the target SOC. From then on, if there is a PV surplus, the charge/discharge control device 10 charges the on-board storage battery 311.

In addition, the setting of the target SOC and target time in this embodiment is a mechanism for using the on-board storage battery 311 as a storage battery until the vehicle 31 is driven (i.e., during the period when the vehicle 31 is not being used for mobility purposes). Therefore, as a general rule, it is not recommended to set the target time to a time period between daytime and nighttime.
When the target time is set to a time period from daytime to nighttime, the control in this embodiment may not be used, and a full charge mode may be used in which the in-vehicle storage battery 311 is forcibly charged until its SOC reaches 100%.

7 is a diagram showing an example of the relationship between the PV power generation amount, the V2H charge/discharge amount, and the home power consumption amount according to the first embodiment. With reference to the diagram, an example of the time-dependent changes in the PV power generation amount, the V2H charge/discharge amount, the home power consumption amount, and the SOC of the in-vehicle storage battery 311 will be described.
Figure 7(A) shows an example of the change over time in PV power generation, V2H charge/discharge amount, and in-home power consumption, and Figure 7(B) explains an example of the change over time in the SOC of the vehicle storage battery 311, with the horizontal axis representing time.

Between 7:00 and 9:00, in-home consumption exceeds 2 [KW (kilowatts)], which is large. Therefore, there is a PV shortage, and the on-board battery 311 discharges to the load 57, causing the SOC of the on-board battery 311 to decrease from 66% to 63%.

When in-home consumption drops to 1 kW between 9:00 and 16:00, a PV surplus occurs, and the charge/discharge control device 10 charges the vehicle storage battery 311. Between 9:00 and 16:00, the SOC of the vehicle storage battery 311 increases from 65% to 84%.

From 4:00 PM to midnight, in-home consumption again exceeds 2 kW and increases. After sunset, the amount of power generated by the solar panel 21 drops to zero, and the on-board battery 311 begins discharging again. From 4:00 PM to midnight, the SOC of the on-board battery 311 decreases from 82% to 50%.

From midnight to 5:00, in-home consumption will be 0 [kW]. From midnight to 1:00, no charging or discharging will occur.

At 1:00, the charging start time has arrived, and the charge/discharge control device 10 starts charging the in-vehicle storage battery 311. Since this time period is a nighttime electricity rate period, charging can be performed at a low electricity rate even if power is supplied from the grid power 62. Between 1:00 and 5:00, the charge/discharge control device 10 charges the in-vehicle storage battery 311 until the target SOC is reached. Between 1:00 and 5:00, the SOC of the in-vehicle storage battery 311 increases from 55% to 70%.
That is, in this example, the target SOC is 70% and the target time is 5:00.

From 5:00 to 7:00, PV power generation begins with sunrise, and household consumption begins to increase. The charge/discharge control device 10 prioritizes supplying surplus PV power to the load 57, and discharges the shortfall from the onboard storage battery 311.

[Summary of the First Embodiment]
As described above, the charge/discharge control device 10 according to this embodiment includes the target SOC acquisition unit 110 to acquire a target SOC, the target time acquisition unit 120 to acquire a target time, the calculation unit 130 to calculate a charge start time based on the target SOC and the target time, the current time acquisition unit 140 to acquire the current time, and the control unit 150 to control the start of charging when the charge start time arrives and the stop of charging when it is determined that the SOC of the in-vehicle storage battery 311 has reached the target SOC. That is, according to this embodiment, the charge/discharge control device 10 controls the in-vehicle storage battery 311 to be charged to the target SOC at the target time. Therefore, according to this embodiment, the user can use the vehicle 31 for mobility purposes and can also store surplus power generated by the solar panel 21. Therefore, according to this embodiment, the charge/discharge control device 10 can achieve both mobility purposes and storage battery purposes for a vehicle equipped with an in-vehicle storage battery.

Furthermore, according to this embodiment, the charge/discharge control device 10 is equipped with a calculation unit 130, and thereby calculates the charge start time based on the difference between the current SOC and the target SOC of the on-board storage battery 311 and the charging power of the on-board storage battery 311. In other words, if the charging power is fast, the time between the target time and the charging start time is short, and if the charging power is slow, the time between the target time and the charging start time is long. Therefore, according to this embodiment, even if the charging power differs depending on the type or degree of deterioration of the on-board storage battery 311, it is possible to accurately control the on-board storage battery 311 to charge up to the target SOC at the target time.

Furthermore, according to this embodiment, the charging power in the charge/discharge control device 10 is a predetermined constant value. Because the charge/discharge control device 10 calculates the charging start time based on the charging power, which is a constant value, the charging start time can be easily calculated.

Furthermore, according to this embodiment, the calculation unit 130 learns the charging power based on the charging time and charge amount required to charge the on-board storage battery 311. Furthermore, the calculation unit 130 calculates the charging start time based on the learned charging power. Therefore, according to this embodiment, the calculation unit 130 can accurately control the on-board storage battery 311 to be charged to the target SOC at the target time, even if the charging power changes due to deterioration of the on-board storage battery 311, etc.

Furthermore, according to this embodiment, the charge/discharge control device 10 controls charging of the on-board storage battery 311 from the solar cell, which is a DC power source, and discharging from the on-board storage battery 311 to the load 57. Furthermore, the control unit 150 determines the direction of power flow based on sensor output information acquired by the current sensor 55. That is, according to this embodiment, the charge/discharge control device 10 determines the direction of power flow using the current sensor 55, and performs charging or discharging according to the determined direction of power flow. Therefore, according to this embodiment, the charge/discharge control device 10 can easily determine whether to charge or discharge the on-board storage battery 311.

Second Embodiment
Next, a second embodiment will be described with reference to Figures 8 and 9. A charge/discharge control device 10A according to the second embodiment differs from the charge/discharge control device 10 in that the charge/discharge control device 10A further performs control based on an "upper SOC limit value" and an "lower SOC limit value."

The "SOC upper limit" is the upper limit of the SOC that can be charged to the in-vehicle storage battery 311. The "SOC upper limit" is generally 100%, and does not necessarily need to be set by the user.
The "SOC lower limit" is the lower limit of the SOC that can be discharged from the in-vehicle storage battery 311. The charge/discharge control device 10A discharges within the range up to the set "SOC lower limit." In other words, whenever the user uses the vehicle 31 for mobility purposes, the SOC set by the "SOC lower limit" is ensured.
The "SOC upper limit value" or the "SOC lower limit value" may be set independently in each of the vehicle 31 and the charge/discharge control device 10. The "SOC upper limit value" set in the charge/discharge control device 10 is preferably set to a value lower than the "SOC upper limit value" preset in the vehicle 31. The "SOC lower limit value" set in the charge/discharge control device 10 is preferably set to a value higher than the "SOC lower limit value" preset in the vehicle 31.

8 is a diagram showing an example of the functional configuration of a charge/discharge control device according to the second embodiment. An example of the functional configuration of a charge/discharge control device 10A will be described with reference to the same figure.
The charge/discharge control device 10A differs from the charge/discharge control device 10 in that it includes an SOC fluctuation range acquisition unit 160. In the description of the charge/discharge control device 10A, the same components as those in the charge/discharge control device 10 are denoted by the same reference numerals, and the description thereof may be omitted.

The SOC variation range acquisition unit 160 includes an SOC lower limit value acquisition unit 161 and an SOC upper limit value acquisition unit 162 .
The SOC lower limit value acquisition unit 161 acquires a lower limit value of the SOC of the in-vehicle storage battery 311 when discharging from the in-vehicle storage battery 311 to a load. Information including the SOC lower limit value is also referred to as SOC lower limit value information ISL. The SOC lower limit value acquisition unit 161 outputs the SOC lower limit value information ISL to the control unit 150.
The SOC upper limit value acquisition unit 162 acquires the upper limit value of the SOC of the on-board storage battery 311 when the on-board storage battery 311 is charged from the grid power 62 or the solar panel 21. Information including the upper limit value of the SOC is also referred to as SOC upper limit value information ISU. The SOC upper limit value acquisition unit 162 outputs the SOC upper limit value information ISU to the control unit 150.

The control unit 150 controls the discharge from the on-board battery 311 to the load 57, and when the SOC of the on-board battery 311 reaches a lower limit, controls the discharge from the on-board battery 311 to the load 57 to stop. The control unit 150 also controls the charging of the on-board battery 311 from the grid power 62 or the solar panel 21, and when the SOC of the on-board battery 311 reaches an upper limit, controls the charging of the on-board battery 311 from the grid power 62 or the solar panel 21 to stop.

9 is a diagram showing an example of a user request acquisition screen according to the second embodiment. An example of a user request acquisition screen D10A will be described with reference to the drawing. D10A differs from the user request acquisition screen D10 in that it includes a text box D13 and a text box D14. In describing the user request acquisition screen D10A, components similar to those of the user request acquisition screen D10 are denoted by similar reference numerals, and description thereof may be omitted.
The text box D13 allows the user to input information in a predetermined manner to obtain the SOC lower limit value. The text box D14 allows the user to input information in a predetermined manner to obtain the SOC upper limit value. In the example shown in the figure, the SOC lower limit value is 30% and the SOC upper limit value is 100%.

The SOC upper limit and SOC lower limit may be set in step S110, which was described with reference to Figure 5. The user sets the "SOC upper limit" and "SOC lower limit" using a predetermined method. Based on the user's settings, the charge/discharge control device 10A acquires information about the "SOC upper limit" and "SOC lower limit."

In step S150 described with reference to FIG. 5, the charge/discharge control device 10A stops charging when the SOC of the in-vehicle storage battery 311 reaches the "SOC upper limit" acquired in step S110.
Furthermore, in step S170 described with reference to Figure 5, even in the case of a PV shortage, if the SOC of the vehicle storage battery 311 reaches the "SOC lower limit value" obtained in step S110, the charge/discharge control device 10A stops discharging from the vehicle storage battery 311 to the load 57.

[Summary of the second embodiment]
As described above, the charge/discharge control device 10A according to this embodiment is provided with the SOC lower limit value acquisition unit 161 to acquire the SOC lower limit value of the in-vehicle storage battery 311, and is provided with the control unit 150 to perform control so as to stop discharging from the in-vehicle storage battery 311 to the load 57 when the SOC of the in-vehicle storage battery 311 reaches the SOC lower limit value. That is, the charge/discharge control device 10A controls charging and discharging within a range that does not fall below the set "SOC lower limit value." Therefore, according to this embodiment, the user can use the vehicle 31 for mobility purposes in a state in which the required SOC is secured, regardless of when the user uses the vehicle 31 for mobility purposes.

Furthermore, according to this embodiment, the charge/discharge control device 10A is equipped with an SOC upper limit value acquisition unit 162 to acquire the SOC upper limit value of the on-board storage battery 311, and is equipped with a control unit 150 to control charging of the on-board storage battery 311 from the grid power 62 or the solar panel 21 to stop when the SOC of the on-board storage battery 311 reaches the SOC upper limit value. In other words, the charge/discharge control device 10A controls charging and discharging within a range that does not exceed the set "SOC upper limit value." Therefore, according to this embodiment, the user can prevent unnecessary overcharging of the on-board storage battery 311. Therefore, the charge/discharge control device 10A can save on electricity costs without charging unnecessary power from the grid power 62.

Furthermore, according to this embodiment, the charge/discharge control device 10A includes the SOC variation range acquisition unit 160, thereby acquiring an SOC range for controlling charge/discharge. The charge/discharge control device 10A controls charge/discharge so that the SOC range of the in-vehicle storage battery 311 falls within the acquired SOC range. In other words, when the user uses the vehicle 31 for mobility purposes, the charge/discharge control device 10A controls the SOC range of the in-vehicle storage battery 311 so that it falls within the acquired SOC range.
Therefore, according to this embodiment, the charge/discharge control device 10A can be used for both mobility purposes and storage battery purposes of the vehicle 31 equipped with the on-board storage battery 311.

[Third embodiment]
Next, a third embodiment will be described with reference to Fig. 10. A charge/discharge control device 10B according to the third embodiment has a function of determining whether the on-board storage battery 311 has deteriorated, and if it is determined that the on-board storage battery 311 has deteriorated, notifies the user that the on-board storage battery 311 has deteriorated. This differs from the charge/discharge control device 10.

Here, the degree of deterioration of the storage battery can be determined based on the charging power. Therefore, in the third embodiment, a predetermined charging power is determined in advance, and the degree of deterioration of the storage battery is determined based on the results of comparing this with the calculated charging power of the in-vehicle storage battery 311.

10 is a diagram showing an example of the functional configuration of a charge/discharge control device according to the third embodiment. With reference to the diagram, an example of the functional configuration of a charge/discharge control device 10B will be described.
The charge/discharge control device 10B differs from the charge/discharge control device 10 in that it includes a notification unit 170. In the description of the charge/discharge control device 10B, the same components as those in the charge/discharge control device 10 are denoted by the same reference numerals, and the description thereof may be omitted.

The charge/discharge control device 10B uses a rated charge power acquisition unit (not shown) to acquire information about the rated charge power of the in-vehicle storage battery 311. The rated charge power acquisition unit may acquire pre-stored rated charge power from a storage unit (not shown).
The notification unit 170 notifies whether the charging power calculated by the calculation unit 130 is equal to or less than a predetermined rated charging power. For example, the notification unit 170 may determine that the in-vehicle storage battery 311 is degraded when the charging power calculated by the calculation unit 130 is equal to or less than the predetermined rated charging power. When the notification unit 170 determines that the in-vehicle storage battery 311 is degraded, the notification unit 170 notifies that the in-vehicle storage battery 311 is degraded.

The notification unit 170 may, for example, have a wireless communication device (not shown), and may use the wireless communication device to notify the mobile terminal device 71 via the router 56 and a predetermined communication network NW that the on-board storage battery 311 has deteriorated.
As a variant, the notification unit 170 may notify the driver that the in-vehicle storage battery 311 is deteriorating by turning on or blinking a light emitting diode (LED) (not shown), or by displaying a message on a display unit (not shown) such as a liquid crystal display.

[Summary of the Third Embodiment]
As described above, the charge/discharge control device 10B according to this embodiment includes the notification unit 170, and notifies the user that the in-vehicle storage battery 311 is degraded when the charge power calculated by the calculation unit 130 is equal to or less than a predetermined rated charge power. Therefore, according to this embodiment, the user can recognize that the in-vehicle storage battery 311 is degraded.

[Fourth embodiment]
Next, a fourth embodiment will be described with reference to Fig. 11 and Fig. 12. A charge/discharge control device 10C according to the fourth embodiment differs from the charge/discharge control device 10 in that the charge/discharge control device 10C further performs control based on a "priority charging time period."
The "priority charging time period" is a time period during which charging of the in-vehicle storage battery 311 is prioritized.

11 is a diagram showing an example of the functional configuration of a charge/discharge control device according to the fourth embodiment. An example of the functional configuration of a charge/discharge control device 10C will be described with reference to the same figure.
The charge/discharge control device 10C differs from the charge/discharge control device 10 in that it includes a charge priority time slot acquisition unit 180. In the description of the charge/discharge control device 10C, the same components as those in the charge/discharge control device 10 are denoted by the same reference numerals, and the description thereof may be omitted.

The priority charging time slot acquisition unit 180 acquires the priority charging time slot. Information including the priority charging time slot is also referred to as priority charging time slot information IPT. The priority charging time slot acquisition unit 180 outputs the priority charging time slot information IPT to the control unit 150.
The control unit 150 controls the in-vehicle storage battery 311 to start charging during the acquired charge priority time slot, regardless of the charging start time.

If the current time is not within the charge priority time zone, the charge start time has not yet been reached, and the direction of the current indicated in the sensor output information acquired by the current sensor 55 is the direction of discharging from the solar panel 21 to the grid power 62, the control unit 150 prioritizes charging from the solar panel 21 to the vehicle storage battery 311.
In addition, the control unit 150 prioritizes discharging the onboard storage battery 311 if the current time is not within the charge priority time zone, the charge start time has not been reached, and the direction of the current indicated in the sensor output information acquired by the current sensor 55 is not discharging from the solar panel 21 to the grid power 62 (i.e., if power is being purchased from the grid power 62).

12 is a diagram showing an example of a user request acquisition screen according to the fourth embodiment. An example of a user request acquisition screen D10C will be described with reference to the same figure. D10C differs from the user request acquisition screen D10 in that it includes a text box D5. In the description of the user request acquisition screen D10C, components similar to those of the user request acquisition screen D10 are denoted by similar reference numerals, and description thereof may be omitted.
In the text box D15, the user inputs information in a predetermined manner to obtain the priority charging time period. In the example shown in the figure, the priority charging time period is from 24:00 to 6:00.

The priority charging time period may be set in step S110, which was described with reference to Figure 5. The user sets the "priority charging time period" using a predetermined method. Based on the user's setting, the charge/discharge control device 10C acquires information about the "priority charging time period."

[Summary of the Fourth Embodiment]
As described above, the charge/discharge control device 10C according to this embodiment acquires the priority charging time slot by including the priority charging time slot acquisition unit 180, and controls the start of charging during the acquired priority charging time slot regardless of the charging start time by including the control unit 150. Note that it is assumed that the priority charging time slot is set during the night or late night hours.
Therefore, according to this embodiment, the user can set a priority charging time period, and the charge/discharge control device 10C can charge the in-vehicle storage battery 311 preferentially during the night when electricity rates are low.

Furthermore, according to this embodiment, the charge/discharge control device 10C is equipped with a control unit 150, and therefore prioritizes charging from the solar panel 21 to the onboard storage battery 311 when it is not a charge priority time period, the charging start time has not been reached, and the direction of the current indicated in the sensor output information acquired by the current sensor 55 is the direction of discharging from the solar panel 21.
Furthermore, according to this embodiment, the charge/discharge control device 10C is equipped with a control unit 150, and therefore prioritizes discharging the on-board storage battery 311 when it is not a charge priority time period, the charge start time has not been reached, and the direction of the current indicated in the sensor output information acquired by the current sensor 55 is not the direction of discharging from the solar panel 21.
The non-priority charging time period is assumed to be a daytime time period. Therefore, according to this embodiment, when the priority charging time period is set to a nighttime or late-night time period, the charge/discharge control device 10C can suitably control charge/discharge even during the daytime.

In addition, all or part of the functions of each unit of the charge/discharge control device 10 in the above-described embodiment may be realized by recording a program for realizing these functions on a computer-readable recording medium, and loading and executing the program recorded on this recording medium into a computer system. Note that the term "computer system" here includes hardware such as the OS and peripheral devices.

In addition, "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage units such as hard disks built into computer systems. Furthermore, "computer-readable recording medium" may also include devices that dynamically store programs for a short period of time, such as communication lines when transmitting programs over networks like the Internet or communication lines like telephone lines, or devices that store programs for a fixed period of time, such as volatile memory within computer systems that serve as servers or clients in such cases. Furthermore, the above-mentioned programs may be those that implement some of the functions described above, or may be those that can implement the functions described above in combination with programs already stored in the computer system.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

1...Charge/discharge system, 10...Charge/discharge control device, 11...Power supply changeover switch, 20...House, 21...Solar panel, 23...PV power conditioner, 22...Connection box, 31...Vehicle, 311...In-vehicle storage battery, 32...DC link V2H, 33...AC link type V2H, 41...Storage battery, 51...Grid connection breaker, 52...Switching box, 53...Audio monitor, 54...Distribution board, 55...Current sensor, 56...Router, 57...Load, 571...100V load, 572...200 V load, 61... smart meter, 62... grid power, 63... main breaker, 71... mobile terminal device, NW... communication network, 110... target SOC acquisition unit, 120... target time acquisition unit, 130... calculation unit, 140... current time acquisition unit, 150... control unit, 160... SOC fluctuation range acquisition unit, 161... SOC lower limit value acquisition unit, 162... SOC upper limit value acquisition unit, 170... notification unit, 180... charging priority time zone acquisition unit, D10... user request acquisition screen

Claims (11)

A charge/discharge control device that controls charging of an on-board storage battery from a DC power supply and discharging of the on-board storage battery to a load,
a target SOC acquisition unit that acquires a target SOC indicating an SOC of the in-vehicle storage battery at a target time;
a target time acquisition unit that acquires the target time;
a calculation unit that calculates a charging start time , which is a time to start charging the on-board storage battery, at predetermined regular time intervals based on the target SOC and the target time so that charging is completed by the target time ;
a current time acquisition unit that acquires the current time;
a control unit that compares the acquired current time with the calculated charging start time, and controls to start charging when the charging start time arrives, and controls to stop charging when it is determined that the SOC of the vehicle storage battery has reached the target SOC. an SOC lower limit value acquisition unit that acquires a lower limit value of an SOC of the vehicle storage battery when discharging from the vehicle storage battery to a load;
The charge/discharge control device according to claim 1, wherein the control unit controls discharging from the vehicle storage battery to the load, and when the SOC of the vehicle storage battery reaches the lower limit value, controls to stop discharging from the vehicle storage battery to the load. 3. The charge/discharge control device according to claim 1, wherein the calculation unit calculates the charge start time based on a difference between a current SOC of the vehicle-mounted storage battery and the target SOC, and charging power that is a rate at which the vehicle-mounted storage battery is charged. the charging power is a constant value,
The charge/discharge control device according to claim 3 , wherein the calculation unit calculates the charge start time based on the preset charge power. The charge/discharge control device according to claim 3 , wherein the calculation unit learns the charging power based on a charging time and a charging amount required to charge the vehicle-mounted storage battery, and calculates the charging start time based on the learned charging power. The charge/discharge control device according to claim 5 , further comprising a notification unit that notifies whether the charge power calculated by the calculation unit is equal to or less than a predetermined rated charge power. further comprising a priority charging time slot acquisition unit that acquires a priority charging time slot;
The charge/discharge control device according to claim 1 , wherein the control unit controls the charging to start during the acquired charge priority time slot regardless of the charge start time. the DC power source is a solar cell that converts light energy into DC power;
8. The charge/discharge control device according to claim 1, wherein the control unit determines a direction of power flow based on sensor output information acquired by a current sensor that acquires information about power supplied from a grid power to a load or power supplied from the DC power source to the grid power. The charge/discharge control device according to claim 8 dependent on claim 7, wherein the control unit prioritizes charging from the solar cell to the on-board storage battery when the time is not the charge priority time slot, the charge start time has not been reached, and the direction of the power flow indicated in the sensor output information is a reverse power flow to the grid power, and prioritizes discharging of the on-board storage battery when the time is not the charge priority time slot, the charge start time has not been reached, and the direction of the power flow indicated in the sensor output information is a forward power flow from the grid power. a computer that controls charging from a DC power supply to an on-board storage battery and discharging from the on-board storage battery to a load;
a target SOC acquisition step of acquiring a target SOC indicating an SOC of the in-vehicle storage battery at a target time;
a target time acquisition step of acquiring the target time;
a calculation step of calculating a charging start time , which is a time to start charging the on-board storage battery, at predetermined regular time intervals based on the target SOC and the target time so that charging is completed by the target time ;
a current time acquisition step for acquiring the current time;
a control step of comparing the acquired current time with the calculated charging start time, and controlling to start charging when the charging start time has arrived, and controlling to stop charging when it is determined that the SOC of the on-board storage battery has reached the target SOC. A charge/discharge control method for controlling charging of an on-board storage battery from a DC power supply and discharging of the on-board storage battery to a load, comprising:
a target SOC acquisition step of acquiring a target SOC indicating an SOC of the on-board storage battery at a target time;
a target time acquisition step of acquiring the target time;
a calculation step of calculating a charging start time , which is a time to start charging the on-board storage battery, at predetermined regular time intervals based on the target SOC and the target time so that charging is completed by the target time ;
a current time acquisition step of acquiring the current time;
a control step of comparing the acquired current time with the calculated charging start time, and controlling to start charging when the charging start time has arrived, and controlling to stop charging when it is determined that the SOC of the on-board storage battery has reached the target SOC.