1. An electric power transaction system for an electric vehicle, the electric power transaction system configured to transaction electric power for charging and discharging of a battery of the electric vehicle, the electric power transaction system characterized by comprising:

a display device configured to display a current transaction price of power; and

at least one processor configured to set exercise contents for trading power of the battery in response to an instruction of a user, and to control charging and discharging of the battery according to the exercise contents set.

2. The electric power trading system of claim 1, wherein the processor is configured to set as the exercise content an exercise that does not select a power sale for selling the electric power of the battery when the current trading price of electric power is a price below a predetermined threshold.

3. The electric power transaction system according to claim 1, wherein the processor is configured to control charging and discharging of the battery in response to the indication of the user to make an allowable charge amount of the battery larger than a usual allowable charge amount.

4. The power trading system of claim 1, wherein the processor is configured to set the exercise content based on the exercise content selected by the user from a plurality of exercise contents for trading the power of the battery.

5. The electric power transaction system according to claim 4, wherein the pieces of exercise content for trading the electric power of the battery include electric power selling, electric power purchasing, and electric power storage.

6. A charge-discharge device configured to control charging and discharging of a battery in an electric power transaction system for an electric vehicle that transactions electric power for charging and discharging of the battery of the electric vehicle, characterized by comprising:

a display device configured to display a current transaction price of power; and

at least one processor configured to set exercise contents for trading power of the battery in response to an instruction of a user, and to control charging and discharging of the battery according to the exercise contents set.

Background

Electric vehicles comprising a battery are well known. Examples of the electric vehicle include an electric vehicle and a hybrid vehicle that use battery power as a drive source. The electric vehicle in this specification may be any vehicle as long as it includes a battery. Generally, a battery of an electric vehicle is charged by connecting the electric vehicle to a charging station or a charge and discharge device provided in a home.

There has been a system for processing electric power transaction by charging and discharging between an electric vehicle and a charge and discharge device. For example, japanese unexamined patent application publication No. 2011-55572 discloses a system in which a user of an electric vehicle pays an electric fee to a side of a charge and discharge device when electric power is supplied from the charge and discharge device to the electric vehicle, and the charge and discharge device pays an electric fee to the user of the electric vehicle when electric power is supplied from the electric vehicle to the charge and discharge device.

Disclosure of Invention

However, in the same manner as, for example, stock prices, the transaction price, which is a purchase price or a sale price of electricity, may vary with time based on the relationship between supply and demand of electricity, or the like. In this case, it is conceivable to use (sell, buy, hold, etc.) the electric power of the electric vehicle as a stock. In the operation of trading the electric power of the electric vehicle, the user of the electric vehicle may determine the operation content of the electric power of the electric vehicle after grasping the current trading price of the electric power.

The electric power transaction system for an electric vehicle disclosed in the present specification enables a user of the electric vehicle to determine an operation content for trading electric power of the electric vehicle according to a current trading price of the electric power.

The electric power trading system for an electric vehicle according to the first aspect of the present invention is configured to trade electric power for charging and discharging of a battery of the electric vehicle. The electric power trading system comprises a display device and at least one processor, wherein the display device is configured to display a current trading price of electric power, the at least one processor is configured to respond to an instruction of a user to set an exercise content of the electric power for trading a battery, and control charging and discharging of the battery according to the set exercise content.

With the above configuration, since the current transaction price of electric power is displayed on the display device, the user can easily grasp the current transaction price of electric power. Therefore, the user can determine the operation content of the electric power for trading the electric vehicle according to the current trading price of the electric power.

In the above-described aspect, when the current transaction price of electric power is a price lower than a predetermined threshold, the processor may set, as the operation content, an exercise of electric power selling that does not select electric power of the selling battery.

In the above scheme, the processor may control the charging and discharging of the battery in response to an instruction from a user to make an allowable charge amount of the battery larger than a normal allowable charge amount.

In the above-described aspect, the processor may set the operation content based on an operation content selected by a user from a plurality of operation contents for trading the power of the battery.

In the above-described aspect, the plurality of exercise contents for trading the power of the battery may include power selling, power purchasing, and power storing.

Further, the charge-discharge device according to the second aspect of the invention is configured to control charging and discharging of the battery in an electric power trading system for an electric vehicle that trades electric power for charging and discharging of the battery of the electric vehicle. The charging and discharging apparatus includes a display device configured to display a current transaction price of electric power, and at least one processor configured to set an exercise content for trading the electric power of the battery in response to an instruction of a user, and to control charging and discharging of the battery according to the set exercise content.

With aspects of the present invention, a user of an electric vehicle can determine the contents of the operation of electric power for trading the electric vehicle according to the current trading price of electric power.

Drawings

Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals denote like elements, and wherein:

fig. 1 is a schematic diagram of the configuration of an electric power transaction system according to the present embodiment;

fig. 2 is a schematic diagram of the configuration of an electric vehicle according to the present embodiment;

fig. 3 is a schematic diagram of a configuration of a charge and discharge device according to the present embodiment;

fig. 4 is a diagram showing an example of a transaction price display screen;

fig. 5 is a schematic diagram of the configuration of a server according to the present embodiment;

FIG. 6 is a graph showing the price of a power transaction over time;

fig. 7 is a schematic diagram of a configuration of an electric vehicle according to a modified embodiment;

fig. 8 is a schematic diagram of a configuration of a user terminal according to a modified embodiment; and

fig. 9 is a flowchart showing a flow of processing of the electric power transaction system according to the present embodiment.

Detailed Description

Fig. 1 is a schematic diagram of the configuration of an electric power transaction system 10 for an electric vehicle according to the present embodiment. The electric power trading system 10 includes an electric vehicle 12, a charge and discharge device 14, a server 16, an electric power company 18, and a user terminal 20. The charge and discharge device 14, the server 16, and the electric power company 18 are communicably connected to each other via a communication line 22 such as a LAN or the internet. Further, the electric vehicle 12 and the user terminal 20 may be communicably connected to the charge and discharge device 14 via wired or wireless near field communication.

Further, a power transmission line is provided between the charge and discharge device 14 and the power company 18, and electric power is transmitted/received between the charge and discharge device 14 and the power company 18 via the power transmission line. Further, the electric vehicle 12 and the charge-discharge device 14 are connected to each other via a power cable or the like so as to be able to transmit/receive electric power. Alternatively, the electric vehicle 12 and the charge and discharge device 14 may be able to transmit/receive electric power therebetween without any contact. The dashed arrows in fig. 1 represent power transmission/reception paths.

The electric vehicle 12, the charge and discharge device 14, and the server 16 will be described in detail below.

The power company 18 transmits power from the grid to the charge and discharge device 14. Further, the power company 18 may also receive power from the charge and discharge device 14. The utility 18 determines a transaction price that includes a price to purchase power from the utility 18 (purchase price) and a price to sell power to the utility 18 (sell price). The transaction price may vary over time depending on, for example, the balance between supply and demand for electricity. Other devices, such as charging and discharging devices 14, may obtain the current transaction price 82 of power by accessing the utility company 18 via the communication line 22.

The user terminal 20 is a mobile terminal, such as a smartphone or a tablet terminal, and is carried by a user (hereinafter simply referred to as "user") of the electric vehicle 12. The user terminal 20 includes a communication unit composed of a network adapter or the like, a storage unit composed of a RAM, a ROM, or the like, a display unit composed of a liquid crystal display or the like, an input unit composed of a touch panel, buttons, or the like, and a control unit composed of a CPU, a microcomputer, or the like.

In the electric power trading system 10, electric power of the electric vehicle 12 may be traded between a user and an electric power company 18. Specifically, when the user purchases electric power from the electric power company 18 and supplies the electric power to the electric vehicle 12 from the charge and discharge device 14, the user pays an electric power fee to the electric power company 18 according to the transaction price. Further, when the user sells electric power to the electric power company 18 and supplies electric power from the electric vehicle 12 to the charge and discharge device 14, the electric power company 18 pays an electric power fee to the user according to the transaction price.

The power trading system 10 may include a wholesale power trading center in which power is traded. In this case, the user may trade power with the wholesale power trading center.

Fig. 2 is a schematic diagram of the configuration of the electric vehicle 12. The electric vehicle 12 includes a battery that stores electric power, and may be, for example, an electric vehicle or a hybrid vehicle that uses electric power as a drive source. As described above, the electric vehicle 12 may be any vehicle as long as it includes a battery.

The communication unit 30 is constituted by, for example, a BluetoothThe near field network adapter of the adapter. The communication unit 30 exhibits a function of communicating with the charge and discharge device 14 via wired or wireless near field communication. Further, the communication unit 30 may be composed of a network adapter or the like, and may be capable of communicating with the server 16 and the electric power company 18 via the communication line 22.

The battery 32 is a secondary battery such as a lithium battery. The electric power is stored in the battery 32, and the electric vehicle 12 can be driven by using the electric power of the battery 32 as a driving source. In the electric power transaction system 10, the user can use the electric power of the battery 32 as an asset.

The power connector 34 is used to connect a power cable. By connecting the electric vehicle 12 to the charge and discharge device 14 via the power cable, electric power can be transmitted/received between the electric vehicle 12 and the charge and discharge device 14. Specifically, when the electric vehicle 12 receives the electric power supplied from the charge-discharge device 14, the battery 32 is charged, and when the battery 32 is discharged, the electric power is supplied from the electric vehicle 12 to the charge-discharge device 14.

The power generation unit 36 is composed of, for example, a solar panel. The power generation unit 36 has a power generation function, and charges the battery 32 with the generated electric power. The power generation unit 36 may be able to generate power even when the electric vehicle 12 is not running, for example, when the vehicle is parked in a parking lot, as with solar power generation using a solar panel. With such a power generation unit 36, the battery 32 can be charged with electric power as an asset transaction even when the electric vehicle 12 is not running.

The control unit 38 includes, for example, an ECU (electronic control unit). The control unit 38 controls each unit of the electric vehicle 12. Further, as shown in fig. 2, the control unit 38 may also function as an allowable charge amount control unit 40.

The allowable charge amount control unit 40 controls the allowable charge amount of the battery 32. Generally, from the viewpoint of extending the life of the battery 32, the allowable charge amount of the battery 32 is controlled so that it becomes a value smaller than the maximum chargeable amount. However, in the present embodiment, the electric power charging the battery 32 is an asset to be traded. For this reason, the battery 32 can be charged with more electric power. Therefore, according to the instruction of the user, the allowable charge amount control unit 40 increases the allowable charge amount of the battery 32 with respect to the normal allowable charge amount. For example, when the user is selecting a specific operation mode (for example, a mode oriented to the amount of charge) as the operation mode of the electric vehicle 12, the allowable charge amount control unit 40 increases the allowable charge amount of the battery 32 compared to the other operation modes.

Fig. 3 is a schematic diagram of the configuration of the charge and discharge device 14. The charge-discharge device 14 is used to charge and discharge the battery 32 of the electric vehicle 12. The charging and discharging device 14 is installed at a charging station (charging post) on a road or at home of a user.

The charge and discharge device 14 authenticates the user before the user operates. For example, the user is authenticated by inputting a user ID and a password for uniquely identifying the user. Alternatively, the user is authenticated by reading an ID card in which the user ID is written. In this way, the charge and discharge device 14 may determine the user who is operating the charge and discharge device 14.

The communication unit 50 is composed of, for example, a network adapter and a near field network adapter. The communication unit 50 exhibits a function of communicating with other devices such as the server 16 via the communication line 22. Further, the communication unit 50 exhibits a function of communicating with the electric vehicle 12 and the user terminal 20 via wired or wireless near field communication.

The display unit 52 is composed of, for example, a liquid crystal display. Various screens are displayed on the display unit 52.

The input unit 54 is composed of, for example, various buttons or a touch panel. The input unit 54 is used to input an instruction of a user to the charge and discharge device 14.

The large secondary battery 56 is a secondary battery such as a lithium battery. The large-sized storage battery 56 can store a large amount of electric power, and can store at least much more electric power than the battery 32 of the electric vehicle 12.

The power connector 58 is used to connect a power cable that connects the electric vehicle 12 with the charge and discharge device 14.

The power transmission/reception unit 60 is a power transmission/reception port for receiving power from the electric power company 18 (i.e., the grid) and transmitting the power to the grid. When the power transmission/reception unit 60 receives power from the grid, the battery 32 of the electric vehicle 12 connected via the power cable is charged. Further, the power transmission/reception unit 60 may transmit electric power from the discharge battery 32 or the large-sized storage battery 56 of the electric vehicle 12 connected via the power cable to the grid.

The control unit 62 includes, for example, a CPU or a microcomputer. The control unit 62 controls the respective units of the charge and discharge device 14. Further, as shown in fig. 3, the control unit 62 may also function as a display control unit 64, an operation content determination unit 66, and a charge and discharge processing unit 68. The processing of the display control unit 64, the operation content determination unit 66, and the charge and discharge processing unit 68, which will be described below, is performed in a state where the electric vehicle 12 and the charge and discharge device 14 are connected to each other via the power cable.

The display control unit 64 controls the display of the display unit 52. Specifically, the display control unit 64 causes the display unit 52 to display the current transaction price 82 of the electric power acquired by the communication unit 50 from the electric power company 18 (or the wholesale electric power transaction center) via the communication line 22. In the present embodiment, the display control unit 64 causes the display unit 52 to display a trading price display screen including the current trading price 82 of electric power. The display control unit 64 may cause the display unit 52 to display the transaction price display screen in response to an instruction by the user, or cause the display unit 52 to display the transaction price display screen in response to connection of the electric vehicle 12 with the charge and discharge device 14 via the power cable, or detection of the electric vehicle 12 by the charge and discharge device 14 via near field communication.

Fig. 4 shows an example of the transaction price display screen 80. As described above, the current transaction price 82 of the electric power acquired from the electric power company 18 is displayed on the transaction price display screen 80. Since the current trading price 82 changes with time, the display control unit 64 changes the displayed current trading price 82 all the time while the trading price display screen 80 is being displayed. The user can easily grasp the current transaction price 82 by viewing the transaction price display screen 80.

Returning to fig. 3, the exercise content determination unit 66 determines exercise content for trading the power of the battery 32 of the electric vehicle 12 in response to the user's instruction input from the input unit 54. In the present specification, "transaction" refers to exchange of electric power and money, i.e., electric power purchase and electric power sale, between a user and the electric power company 18 (or wholesale electric power trading center), and "use" refers to the following concept: it includes not only electric power purchase and electric power sale but also a method of using electric power, such as electric power storage (details of which will be described below). Further, the operation content determined by the operation content determining unit 66 is a concept including an operation type and an operation power amount.

First, in response to an instruction from the user, the exercise content determination unit 66 selects a selected exercise type from a plurality of exercise types prepared in advance. In the present embodiment, the operation types prepared in advance are power purchase in which the user purchases power from the electric power company 18 to charge the battery 32, power sale in which the user sells power from the discharging battery 32 to the electric power company 18, and power storage in which the user stores power discharged from the battery 32 as the user's power in the large storage battery 56 of the charge and discharge device 14. The types of exercise that can be selected by the user are not limited to the above-described types, and may include, for example, power lending in which the user lends power to another user and power borrowing in which the user lends power from another user.

In the present embodiment, as shown in fig. 4, an operation type selection button 84 that enables the user to select an operation type is displayed on the transaction price display screen 80. The liquid crystal panel serving as the display unit 52 is a touch panel (i.e., a liquid crystal panel serves as the display unit 52 and the input unit 54), and the user can select the selection exercise type by operating the exercise type selection button 84. Specifically, when the user touches the electric power purchase button 84a, the exercise content determining unit 66 selects electric power purchase as the selection exercise type, and when the user touches the electric power selling button 84b, the exercise content determining unit 66 selects electric power selling as the selection exercise type. When the user touches the power storage button 84c, the exercise content determination unit 66 selects power storage as the selected exercise type.

The user may use another method to input a selection of the exercise type. For example, as the input unit 54, a mechanical power purchase button, a power sale button, and a power storage button may be provided, and the exercise content determination unit 66 may select the selection of the exercise type according to the operation of the mechanical button.

Next, after selecting the selection exercise type, the exercise content determination unit 66 determines the amount of exercise power in response to an instruction of the user. In the present embodiment, when the user operates the exercise type selection button 84 on the transaction price display screen 80, the display control unit 64 causes the display unit 52 to display an exercise power amount input screen (not shown) that enables the user to input an amount of exercise power. The user inputs the amount of operating power on the operating power input screen. Specifically, when the user has selected the electric power purchase button 84a, the user inputs the amount of power purchased on the operating electric power amount input screen, and when the user has selected the electric power selling button 84b, the user inputs the amount of power sold on the operating electric power amount input screen. When the user has selected the power storage button 84c, the user inputs the power storage amount on the exercise power amount input screen. Based on the input, the operation content determination unit 66 determines the amount of operation power.

The charge/discharge processing unit 68 executes charge/discharge processing of the battery 32 in accordance with the operation content determined by the operation content determining unit 66. Specifically, when the exercise content determination unit 66 has selected electric power purchase as the selected exercise type, the charge and discharge processing unit 68 charges the battery 32 with electric power corresponding to the determined purchase electric power amount (i.e., the amount purchased by the user) from the electric grid via the electric power transmission/reception unit 60. Further, when the exercise content determination unit 66 has selected electric power selling as the selected exercise type, the charge-discharge processing unit 68 discharges the battery 32 with electric power corresponding to the determined selling amount (i.e., the amount sold by the user) and transmits the electric power to the grid via the electric power transmission/reception unit 60. Further, when the operation content determination unit 66 has selected the electric power storage as the selected operation type, the charge-discharge processing unit 68 discharges the battery 32 by an amount of electricity corresponding to the determined electric power storage amount, and charges the large-sized storage battery 56 with electric power.

When the exercise content determination unit 66 has selected electric power purchase or electric power sale as a selection exercise type and the charge-discharge device 14 has charged/discharged the battery 32 in response to the selection, the control unit 62 of the charge-discharge device 14 transmits electric power transaction information indicating the user ID of the user, the exercise content (exercise type and exercise electric power amount), and the current transaction price 82 of electric power to the server 16. Further, when the exercise content determination unit 66 has selected electric power storage as the selected exercise type and the charge-discharge device 14 has charged the large storage battery 56 with electric power from the discharge battery 32 (stored electric power in the large storage battery 56) in response to the selection, the control unit 62 stores a user ID indicating the user in a storage unit (not shown) of the charge-discharge device 14 in association with the stored amount of electric power.

The user can use the electric power stored in the large storage battery 56 at any time. For example, when the electricity transaction price rises, the user may sell the electricity stored in advance in the large storage battery 56. When the electric power stored in the large storage battery 56 is sold, the control unit 62 also transmits, to the server 16, a user ID indicating the user and information indicating the exercise content. Since the electric power stored in the large-sized storage battery 56 may be an object to be traded later, it can be said that the electric power storage as the operation type is also included in the operation of the electric power of the trading battery 32. Further, when the remaining amount of the battery 32 of the electric vehicle 12 decreases, the battery 32 can be charged with the electric power stored in the large-sized storage battery 56 without purchasing new electric power.

In the present embodiment, electric power is purchased from and sold to the power grid (electric power company 18), but when the above-described wholesale electric power trading center exists, the user can purchase electric power from and sell electric power to the wholesale electric power trading center. In this case, when the user has selected the purchase of electric power, the charge and discharge processing unit 68 may charge the battery 32 with the electric power from the wholesale electric power trading center, and when the user has selected the sale of electric power, the charge and discharge processing unit 68 may transmit the electric power from the battery 32 to the wholesale electric power trading center.

Fig. 5 is a schematic diagram of the configuration of the server 16. The server 16 is composed of a computer, and performs deposit/withdrawal processing for users who have purchased or sold electric power.

The communication unit 90 is constituted by a network adapter, for example. The communication unit 90 exhibits a function of communicating with other devices such as the charge and discharge device 14 via the communication line 22.

The storage unit 92 is composed of, for example, a hard disk, ROM, or RAM. The storage unit 92 stores a user ID of a user registered in advance in the electric power transaction system 10 and information (for example, an account number) indicating a deposit/withdrawal destination of the user in association with each other.

The control unit 94 is composed of, for example, a CPU. As shown in fig. 5, the control unit 94 functions as a transaction processing unit 96.

The transaction processing unit 96 performs deposit/withdrawal processing for the user based on the electric power transaction information received from the charge and discharge device 14. Specifically, when the electric power transaction information whose operation content is electric power purchase is received from the charge and discharge device 14, the transaction processing unit 96 performs withdrawal processing for extracting an amount of money, which is calculated based on the amount of used electric power (purchased electric power) and the electric power transaction price included in the electric power transaction information, from the user indicated by the user ID included in the electric power transaction information. The amount of money withdrawn is transferred to the utility company 18. Further, when the electricity transaction information whose exercise content is electricity selling is received from the charge and discharge device 14, the transaction processing unit 96 performs a deposit process for a deposited amount, which is calculated based on the amount of used electricity (amount of sold electricity) and the electricity transaction price included in the electricity transaction information, to the user indicated by the user ID included in the electricity transaction information. The amount to be deposited is paid by the utility company 18.

As described above, the outline of the electric power trading system 10 according to the present embodiment has been described. With the electric power trading system 10, when the user uses the electric power of the battery 32 of the electric vehicle 12, the current trading price 82 of the electric power is displayed on the display unit 52 of the charge and discharge device 14. Therefore, the user can appropriately determine the content of the application of the electric power as the asset based on the current transaction price 82 of the electric power.

For example, when the electricity transaction price is low, electricity purchase can be positively selected while avoiding selection of electricity sale. On the other hand, when the electricity transaction price is high, electricity sales can be positively selected while avoiding selection of electricity purchase. Further, even if the charge amount of the battery 32 is close to the allowable charge amount (close to the full charge amount), at least a part of the power of the battery 32 can be moved to the large storage battery 56 by selecting the power storage when the current transaction price 82 is low. In this way, the battery 32 can be further charged with the electric power generated by the power generation unit 36. In other words, the amount of electricity as an asset can be further increased. Thereafter, when the electricity transaction price rises, the user may also sell the electricity stored in the large storage battery 56 and the electricity newly charging the battery 32. In this way, the user may profit from the electricity transaction.

Further, a selling price threshold value as a threshold value of the electricity trading price may be set in advance. The set selling price threshold value is stored in advance in the charge and discharge device 14. In this embodiment, the selling price threshold is set by the user. Alternatively, the selling price threshold may be automatically set by the control unit 62 of the charge and discharge device 14. Specifically, the control unit 62 may predict a future change in the transaction price based on the past transaction history of the user and the past change in the electricity transaction price, and then set the selling price threshold value so as to maximize the expected value of the benefit that the electricity transaction of the user will produce.

After setting the selling price threshold, when the current transaction price 82 of the electricity is lower than the selling price threshold, the exercise content determination unit 66 does not select the electricity sale as the exercise type, that is, does not allow the user to sell the electricity (prohibits the electricity sale). Specifically, when the current transaction price 82 of electric power is lower than the selling price threshold, even if the user operates the electric power selling button 84b (see fig. 4) on the transaction price display screen 80, the exercise content determining unit 66 invalidates the operation. Alternatively, the display control unit 64 does not cause the display unit 52 to display the electricity selling button 84b on the transaction price display screen 80.

FIG. 6 is a song showing the change of electricity transaction price over time and a selling price thresholdAnd (6) line drawing. In the graph of fig. 6, the horizontal axis represents time and the vertical axis represents electricity transaction price. The dotted line represents a preset selling price threshold. At the current time t_nThe electricity transaction price is below the selling price threshold. Thus, at the present time t_nThe user is not allowed to sell electricity using the content determination unit 66. When looking at the current time t_nAt a later time, at a slave time t_nTo time t₁While the electricity transaction price is still below the selling price threshold from time t₁To time t₂The electricity trade price is above the sell price threshold for the period of time. In FIG. 6, at time t₂During a later time period, the electricity transaction price is again below the selling price threshold. Therefore, the exercise content determining unit 66 does not allow the user to determine the time t from the time t_nTo time t₁And at time t₂Selling electricity for a later period of time, but allowing the user to do so from time t₁To time t₂Sell electricity during the time period.

Further, when the user has stored the electric power from the battery 32 in the large storage battery 56 of the charge-discharge device 14, the user may be able to set the charge-discharge processing unit 68 in advance such that the charge-discharge processing unit 68 automatically sells the electric power stored in the large storage battery 56 when the electric power trade price reaches the selling price threshold. At the present time t shown in fig. 6_nWhen the user has stored the electric power from the battery 32 in the large-sized storage battery 56 and has set the charge and discharge processing unit 68 as described above, the charge and discharge processing unit 68 reaches the selling price threshold at the time t when the electricity transaction price reaches the selling price threshold₁The consumer's power stored in the large battery 56 is automatically transferred (i.e., sold) to the grid. In this way, the user may automatically sell electricity when the electricity transaction price reaches the selling price threshold. In this case, the user may be able to set the sales electricity amount in advance.

In the present embodiment, the current transaction price 82 of the electric power is displayed on the display unit 52 of the charge and discharge device 14, and the user inputs the operation content of the electric power of the battery 32 to the charge and discharge device 14. However, the display of the current transaction price 82 of electric power and the input of the exercise content may be performed in the electric vehicle 12.

Fig. 7 is a schematic diagram of the configuration of an electric vehicle 12a according to a modified embodiment. The configuration components that exhibit the same functions as those of the electric vehicle 12 in the above-described embodiment are given the same reference numerals as those of fig. 2, and the description thereof will be omitted.

The electric vehicle 12a also includes a display unit 100 composed of a liquid crystal panel or the like, and an input unit 102 composed of a touch panel, buttons, or the like. The control unit 38a of the electric vehicle 12a has the functions of the display control unit 64 and the operation content determination unit 66 that the control unit 62 of the charge and discharge device 14 has in the above-described embodiment.

The display control unit 64 of the electric vehicle 12a receives the current transaction price 82 of electric power from the charge-discharge device 14 via near-field communication, and causes the display unit 100 to display the price. Alternatively, the display control unit 64 of the electric vehicle 12a may directly receive the current transaction price 82 of the electric power by communicating with the electric power company 18 or the wholesale electric power transaction center and cause the display unit 100 to display the price. The display control unit 64 of the electric vehicle 12a may cause the display unit 100 to display the transaction price display screen 80 shown in fig. 4.

The operation content determination unit 66 of the electric vehicle 12a determines the operation content for trading the electric power of the battery 32 according to the instruction of the user input from the input unit 102.

By transmitting the operation content determined by the operation content determining unit 66 to the charge/discharge device 14, the charge/discharge instructing unit 104 causes the charge/discharge device 14 to execute the charge/discharge process on the battery 32 in accordance with the operation content. When the user has selected electric power purchase or electric power sale as the exercise content and the charge and discharge device 14 has charged/discharged the battery 32 in response to the instruction of the charge and discharge instruction unit 104, the charge and discharge instruction unit 104 transmits electric power transaction information to the server 16. Further, when the user has selected power storage as the exercise content and, in response to the selection, the charge-discharge device 14 charges the large storage battery 56 with power from the discharge battery 32 (stored power in the large storage battery 56), the charge-discharge instruction unit 104 transmits, to the charge-discharge device 14, a user ID indicating the user and information indicating the power storage amount, and stores the user ID and the information in a storage unit (not shown) of the charge-discharge device 14.

Further, the display of the current transaction price 82 of electric power and the input of the exercise content may be performed on the user terminal 20.

Fig. 8 is a schematic diagram of the configuration of the user terminal 20a according to the modified embodiment.

The communication unit 110 is composed of a network adapter, a near field network adapter, or the like, and exhibits a function of communicating with the server 16 and the electric power company 18 via the communication line 22. Further, the communication unit 110 exhibits a function of communicating with the charge and discharge device 14 via near field communication. The display unit 112 is composed of a liquid crystal panel or the like, and the input unit 114 is composed of a touch panel, buttons, or the like.

The control unit 116 is composed of, for example, a CPU or a microcontroller. The control unit 116 has the functions of the display control unit 64, the operation content determination unit 66, and the charge and discharge instruction unit 104 that the electric vehicle 12a has in the above-described modified embodiment.

The display control unit 64 of the user terminal 20a causes the display unit 112 to display the current transaction price 82 of the power received from the charge and discharge device 14, the electric power company 18, or the wholesale power transaction center. The display control unit 64 may cause the display unit 112 to display the transaction price display screen 80 shown in fig. 4.

The operation content determination unit 66 of the user terminal 20a determines the operation content for trading the power of the battery 32 according to the user's instruction input from the input unit 114.

Since the process of the charge and discharge instruction unit 104 of the user terminal 20a is the same as the process of the charge and discharge instruction unit 104 of the electric vehicle 12a, a description thereof will be omitted.

Further, the display control unit 64 and the exercise content determination unit 66 do not necessarily have to be included in the same device. For example, the display control unit 64 may be provided in the charge and discharge device 14, and the exercise content determining unit 66 may be provided in the user terminal 20. In this case, the current transaction price 82 of the electric power is displayed on the display unit 52 of the charge and discharge device 14, and the user views the price and inputs the exercise content of the electric power for trading the battery 32 to the user terminal 20.

Hereinafter, the flow of processing of the electric power transaction system 10 will be described with reference to a flowchart shown in fig. 9. At the beginning of the flowchart of fig. 9, it is assumed that the electric vehicle 12 and the charge-discharge device 14 are connected via a power cable.

In step S10, the display control unit 64 of the charge and discharge device 14 causes the display unit 52 to display the trade price display screen 80 including the current trade price 82 of the electric power acquired from the electric power company 18.

In step S12, the user operates one of the exercise type selection buttons 84 included in the transaction price display screen 80 with reference to the current transaction price 82 displayed in step S10. The exercise content determination unit 66 selects an exercise type for trading the power of the battery 32 of the electric vehicle 12 according to an exercise type selection button 84 operated by the user.

When the exercise content determining unit 66 selects power purchase in step S12, the process proceeds to step S14.

In step S14, the user inputs the purchase power amount through the input unit 54 of the charge and discharge device 14. The exercise content determining unit 66 determines the amount of electricity ordered based on the user's input.

In step S16, the charge and discharge processing unit 68 charges the battery 32 of the electric vehicle 12 with the electric power of the grid in accordance with the operation content determined in steps S12 and S14. Thereafter, the control unit 62 of the charge and discharge device 14 transmits power transaction information indicating the user ID indicating the user, the exercise content (exercise type and exercise power amount), and the current transaction price 82 of power to the server 16.

In step S18, the transaction processing unit 96 of the server 16 withdraws money from the user based on the power transaction information received in step S16.

When the exercise content determination unit 66 selects power selling in step S12, the process proceeds to step S20.

In step S20, the exercise content determination unit 66 determines whether the user has set a selling price threshold. When the selling price threshold has been set, the process proceeds to step S22. On the other hand, when the selling price threshold is not set, the process skips step S22 and proceeds to step S24.

In step S22, the exercise content determination unit 66 determines whether the current transaction price 82 of electric power is equal to or higher than the selling price threshold. The process ends here when the current transaction price 82 of electricity is below the selling price threshold. The process may stop until the electricity transaction price reaches the selling price threshold. When the current transaction price 82 of the electric power is equal to or higher than the selling price threshold, the process proceeds to step S24.

In step S24, the user inputs the amount of electricity sold through the input unit 54 of the charge and discharge device 14. The exercise content determining unit 66 determines the amount of electricity sold based on the input from the user.

In step S26, the charge and discharge processing unit 68 transmits the electric power of the battery 32 to the grid according to the exercise contents determined in steps S12 and S24. Thereafter, the control unit 62 of the charge and discharge device 14 transmits the electric power transaction information to the server 16.

In step S28, the transaction processing unit 96 of the server 16 deposits money to the user based on the power transaction information received in step S26.

When the exercise content determination unit 66 selects power storage in step S12, the process proceeds to step S30.

In step S30, the user inputs the power storage amount through the input unit 54 of the charge and discharge device 14. The exercise content determination unit 66 determines the power storage amount according to the input of the user.

In step S32, the charge and discharge processing unit 68 stores the electric power of the battery 32 in the large-sized storage battery 56 of the charge and discharge device 14 according to the exercise contents determined in steps S12 and S30. Thereafter, the control unit 62 of the charge and discharge device 14 stores the user ID indicating the user in association with the power storage amount in the storage unit of the charge and discharge device 14.

Although the embodiment of the electric power transaction system for an electric vehicle according to the present invention has been described above, the electric power transaction system for an electric vehicle according to the present invention is not limited thereto, and various modifications may be made within the scope not departing from the scope of the present invention.