EV charging and discharging system

Abstract

Provided is an EV charging / discharging system comprising: a plurality of charging / discharging stands that are detachably connected to an EV so as to perform charging and discharging of a power storage device mounted on the connected EV; a plurality of bidirectional converters that are provided to correspond to the plurality of charging / discharging stands and perform bidirectional power conversion in a direction in which a power storage device of an EV connected to a corresponding charging / discharging stand is charged and a direction in which the power storage device of the EV connected to the corresponding charging / discharging stand is discharged; and a control device for controlling the operation of the plurality of bidirectional converters. The control device controls the operation of the plurality of bidirectional converters such that the EV connected to each of the plurality of charging / discharging stands has a target charging rate at the end of parking. Accordingly, provided is an EV charging / discharging system with which it is possible to more effectively utilize an EV power storage device while further increasing the convenience of an EV user.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an EV charging / discharging system. [Background technology]

[0002] In order to achieve carbon neutrality, the introduction of power generation facilities using renewable energy is progressing. However, power generation facilities using renewable energy have the problem of difficulty in obtaining a stable amount of power. For example, with solar power generation, the amount of power generated varies depending on the time of day and weather conditions.

[0003] Therefore, it has been proposed to use stationary storage batteries, charging them when power generation is high and discharging them when power generation is low, in order to level out the load on electricity demand.Furthermore, the use of storage devices in EVs (electric vehicles) instead of stationary storage batteries is also being considered.

[0004] An EV charging / discharging system that is connected to a power generation facility that uses renewable energy and a power grid, charges the EV's power storage device using power from at least one of the power generation facility and the power grid, and discharges the power stored in the EV's power storage device to the power grid, can charge the EV and level the load of power demand, making effective use of the EV's power storage device.

[0005] In such an EV charging / discharging system, it is desirable to be able to make more effective use of the EV's power storage device while further improving convenience for EV users. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-282383 [Patent Document 2] Japanese Patent Publication No. 2022-25664 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-85689 Summary of the Invention [Problem to be solved by the invention]

[0007] An embodiment of the present invention provides an EV charging / discharging system that can more effectively utilize an EV's power storage device while further improving convenience for EV users. [Means for solving the problem]

[0008] According to an embodiment of the present invention, there is provided an EV charging / discharging system connected to a power generation facility that uses renewable energy and a power grid, the system comprising: a plurality of charging / discharging stands that are detachably connected to EVs to charge and discharge power storage devices mounted on the connected EVs; a plurality of bidirectional converters that are provided corresponding to the plurality of charging / discharging stands and perform bidirectional power conversion in a direction to charge the power storage device of the EV connected to the corresponding charging / discharging stand and a direction to discharge the power storage device of the EV connected to the corresponding charging / discharging stand; and a control device that controls operation of the plurality of bidirectional converters, wherein, in the power conversion in the charging direction, the plurality of bidirectional converters convert power supplied from at least one of the power generation facility and the power grid into DC power compatible with the EV, and then convert the converted DC power into and supplies the EVs connected to the corresponding charging / discharging stands with DC power supplied from the power storage devices of the EVs connected to the corresponding charging / discharging stands, and in the power conversion in the discharging direction, converts DC power supplied from the power storage devices of the EVs connected to the corresponding charging / discharging stands into power on the power grid side and supplies the converted power to the power grid side. The control device acquires information on parking times of the EVs connected to the plurality of charging / discharging stands and information on target charging rates at the end of parking of the EVs connected to the plurality of charging / discharging stands, and controls operation of the plurality of bidirectional converters in the charging direction during time periods when the amount of power generated by the power generation facility is high, and controls operation of the plurality of bidirectional converters in the discharging direction during time periods when the amount of power generated by the power generation facility is low, based on the acquired parking time information and charging rate information, so that the EVs connected to each of the plurality of charging / discharging stands will have their target charging rates at the end of parking. The control device is capable of acquiring information regarding changes to the parking time of the EV, and performs processing to change the parking time in response to the acquisition of the information regarding changes to the parking time of the EV. If the charging rate of the EV is lower than a target charging rate when the information regarding changes to the parking time of the EV is acquired, the control device performs one of the following as necessary, in descending order of priority, to achieve the target charging rate at the end of the changed parking period: charging the power storage device using surplus power from the power generation facility; charging the power storage device using power stored in the power storage devices of other EVs that are connected to the multiple charging / discharging stations and that can be discharged; stopping charging of the other EVs connected to the multiple charging / discharging stations; and charging the power storage device using power from the power grid. An EV charging and discharging system is provided. [Effects of the Invention]

[0009] According to an embodiment of the present invention, an EV charging / discharging system is provided that can more effectively utilize the EV's power storage device while further improving convenience for EV users. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram schematically illustrating an EV charging / discharging system according to an embodiment. [Figure 2] FIG. 10 is a block diagram schematically illustrating a modified example of the EV charging / discharging system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0012] FIG. 1 is a block diagram schematically illustrating an EV charging / discharging system according to an embodiment. As shown in FIG. 1, an EV charging / discharging system 10 includes a plurality of charging / discharging stations 12, a plurality of bidirectional AC / DC converters 14 (bidirectional converters), and a control device 16.

[0013] The EV charging / discharging system 10 is connected to a power generation facility 2 that uses renewable energy and a power grid 4. The EV charging / discharging system 10 is used together with the power generation facility 2 and the power grid 4. The power grid 4 is, for example, an AC power grid. The power of the power grid 4 is, for example, AC power. However, the power of the power grid 4 is not limited to AC power and may be DC power or the like.

[0014] The power generation facility 2 supplies the generated power to the power grid 4 and the EV charging / discharging system 10. The power generation facility 2 is a grid-connected power generation facility. The power generation facility 2 is, for example, a solar power generation facility. The power generation facility 2 includes, for example, solar panels and a power conversion device that converts DC power generated by the solar panels into AC power compatible with the power grid 4. However, the power generation facility 2 may also be, for example, a wind power generation facility or a geothermal power generation facility. The power generation facility 2 may be any power generation facility that generates power using renewable energy and can be connected to the power grid 4.

[0015] The multiple charging / discharging stands 12 are used for connection to the EVs 6. The multiple charging / discharging stands 12 are devices that are detachably connected to the EVs 6 to charge and discharge the electricity storage devices 6a mounted on the connected EVs 6. In other words, the multiple charging / discharging stands 12 are charging / discharging plugs that are detachably connected to charging / discharging sockets provided on the EVs 6.

[0016] The EV charging / discharging system 10 is connected to EVs 6 via one of a plurality of charging / discharging stands 12. This allows the EV charging / discharging system 10 to charge the number of EVs 6 corresponding to the number of charging / discharging stands 12.

[0017] The EV 6 may be a BEV (Battery Electric Vehicle) powered only by a motor, or a PHEV (Plug-in Hybrid Electric Vehicle) powered by a motor and an engine. The EV 6 may be any vehicle that has a power storage device 6a, runs on DC power stored in the power storage device 6a, and is capable of charging the power storage device 6a from an external power supply. The power storage device 6a of the EV 6 may be, for example, a storage battery or a capacitor. The power storage device 6a may be any device that can store DC power.

[0018] The EV charging / discharging system 10 charges the power storage devices 6a of the EVs 6 connected to multiple charging / discharging stands 12 using power supplied from at least one of the power generation facility 2 and the power grid 4. The EV charging / discharging system 10 also discharges the power stored in the power storage devices 6a of the EVs 6 connected to the multiple charging / discharging stands 12 to the power grid 4. Note that in cases where there are a large number of charging / discharging stands 12 (number of EVs 6 that can be connected) and all of the power generated by the power generation facility 2 can be used to charge the EVs 6, the power generation facility 2 may be a self-consumption power generation facility.

[0019] The multiple charging and discharging stands 12 have a function of communicating with the connected EVs 6. The charging and discharging stands 12 communicate with, for example, the ECU (Electronic Control Unit) of the EVs 6. By communicating with the connected EVs 6, the charging and discharging stands 12 acquire information related to the current state of charge (SOC) of the power storage device 6a from the EVs 6. The information related to the state of charge of the power storage device 6a may be any information that allows the charging and discharging stands 12 to ascertain the current state of charge of the power storage device 6a, such as information related to the voltage value of the power storage device 6a. Furthermore, the information acquired by the charging and discharging stands 12 from the EVs 6 is not limited to information related to the state of charge. The charging and discharging stands 12 may also acquire information related to the optimal current value (current command value) according to the state of the power storage device 6a from the EVs 6, for example.

[0020] The multiple bidirectional AC / DC converters 14 are provided corresponding to the multiple charging / discharging stands 12, respectively, and perform bidirectional power conversion in a direction to charge the power storage device 6a of the EV 6 connected to the corresponding charging / discharging stand 12, and in a direction to discharge the power storage device 6a of the EV 6 connected to the corresponding charging / discharging stand 12.

[0021] The bidirectional AC / DC converter 14 converts AC power supplied from at least one of the power generation facility 2 and the power grid 4 into DC power compatible with the EVs 6, and supplies the converted DC power to the corresponding charging / discharging stand 12. The bidirectional AC / DC converter 14 also converts DC power supplied from the power storage device 6a of the EV 6 connected to the corresponding charging / discharging stand 12 into AC power compatible with the power grid 4, and supplies the converted AC power to the power grid 4.

[0022] In this way, in power conversion in the charging direction, the multiple bidirectional AC / DC converters 14 convert power supplied from at least one of the power generation facility 2 and the power grid 4 into DC power compatible with the EVs 6, and supply the converted DC power to the corresponding charging / discharging stands 12. In power conversion in the discharging direction, the multiple bidirectional AC / DC converters 14 convert DC power supplied from the power storage device 6a of the EV 6 connected to the corresponding charging / discharging stand 12 into power on the power grid 4 side, and supply the converted power to the power grid 4 side.

[0023] As a result, the multiple bidirectional AC / DC converters 14 can supply converted AC power to the power grid 4 and can also supply it to the AC sides of other bidirectional AC / DC converters 14. In other words, the multiple bidirectional AC / DC converters 14 enable selling of power (reverse power flow) to the power grid 4 based on the power stored in the power storage device 6a of the EV 6, and also enable charging of the power storage device 6a of another EV 6 based on the power stored in the power storage device 6a of the EV 6. The bidirectional AC / DC converter 14 is, for example, an AC / DC converter capable of bidirectional power conversion.

[0024] The rated voltage of the DC sides of the multiple bidirectional AC / DC converters 14 is, for example, equal to or higher than the total voltage of the power storage devices 6a of the EVs 6. The total voltage of the power storage devices 6a of the EVs 6 is, for example, about 400 V. In this case, the rated voltage of the DC sides of the multiple bidirectional AC / DC converters 14 is set to 400 V or higher. Note that the rated voltages of the multiple bidirectional AC / DC converters 14 do not necessarily have to be the same.

[0025] The control device 16 controls the operation of the multiple bidirectional AC / DC converters 14. The control device 16 acquires information about the parking time of the EV 6 connected to the multiple charging / discharging stations 12 and information about the target charging rate at the end of parking of the EV 6 connected to the multiple charging / discharging stations 12. More specifically, the parking time information is information that indicates the time from when the EV 6 starts to park until the planned end of parking. More specifically, the charging rate information is information that indicates what percentage of SOC the power storage device 6a should be at when the EV 6 plans to end parking.

[0026] The multiple charging / discharging stands 12 each have an operation panel 12a for inputting information about parking time and charging rate. When a user of an EV 6 connects the EV 6 to a charging / discharging stand 12 to charge or discharge, the user inputs information about parking time and charging rate via the operation panel 12a. The control device 16 communicates with the multiple charging / discharging stands 12 to obtain information about parking time and charging rate from the multiple charging / discharging stands 12.

[0027] The control device 16 has a communication device 16a for communicating with an information terminal (not shown) via a network such as the Internet. The information terminal may be, for example, a smartphone or a personal computer owned by the user of the EV 6, or a dedicated terminal installed in a parking space where multiple charging / discharging stations 12 are installed. When the user of the EV 6 connects the EV 6 to the charging / discharging station 12 to charge or discharge, the user may input information about the parking time and the charging rate via the information terminal. The control device 16 may acquire information about the parking time and the charging rate from the information terminal by communicating with the information terminal via the communication device 16a. Note that communication between the communication device 16a and the information terminal may be wired or wireless.

[0028] In this way, the control device 16 acquires information on the parking time and the charging rate by, for example, communicating with a plurality of charging / discharging stations 12 or information terminals. However, the method of acquiring the information on the parking time and the charging rate is not limited to the above, and any method that allows the control device 16 to appropriately acquire the information on the parking time and the charging rate may be used.

[0029] Based on the acquired parking time information and charging rate information, the control device 16 controls the operation of the multiple bidirectional AC / DC converters 14 in a charging direction during time periods when the amount of power generated by the power generation facility 2 is high, and controls the operation of the multiple bidirectional AC / DC converters 14 in a discharging direction during time periods when the amount of power generated by the power generation facility 2 is low, so that the EVs 6 connected to each of the multiple charging / discharging stations 12 will reach the target charging rate when parking ends.

[0030] For example, if the power generation facility 2 is a solar power generation facility, the amount of power generated by the power generation facility 2 tends to be high during the daytime and low from the evening to the morning. On the other hand, the spot market price in the wholesale electricity market tends to be low during the noon time slot and high during the evening to night time slot. The noon time slot is, for example, from 11:00 to 14:00. The evening to night time slot is, for example, from 15:00 to 21:00.

[0031] Therefore, when the power generation facility 2 is a solar power generation facility, the control device 16 controls the operation of the multiple bidirectional AC / DC converters 14 in a charging direction during the daytime when the amount of power generated by the power generation facility 2 is large, and controls the operation of the multiple bidirectional AC / DC converters 14 in a discharging direction during the time period from evening to morning when the amount of power generated by the power generation facility 2 is small. This makes it possible to increase profits from selling electricity compared to, for example, selling electricity during a time period when the spot market price is low.

[0032] For example, in a business, multiple EVs 6 owned by employees who use them for commuting to work may simply be parked in the business's parking lot during daytime business hours. In such a case, the EV charging / discharging system 10 according to this embodiment can be applied to charge the multiple EVs 6 during daytime business hours (e.g., 11:00 AM to 2:00 PM) and discharge the multiple EVs 6 in the evening (e.g., 3:00 PM to 5:00 PM) just before the employees return home.

[0033] As a result, for example, a business operator operating the power generation facility 2 and the EV charging / discharging system 10 can increase revenue from selling electricity by charging during times when the spot market price is low and discharging during times when the spot market price is high. Employees (users) who own EVs 6 can charge the energy storage devices 6a of the EVs 6 to a desired charge level by the time they return home. For example, in exchange for using the employee's EVs 6 instead of using a stationary storage battery, the EVs 6 can be charged free of charge. This benefits both the business operator and the employees (users) and allows for more effective use of multiple EVs 6 than simply parking them. Furthermore, by charging and discharging the energy storage devices 6a of the EVs 6 so that the target charge level is reached when the EVs are no longer parked (e.g., when they return home), convenience for the users of the EVs 6 can be enhanced.

[0034] Therefore, the EV charging / discharging system 10 according to this embodiment can make more effective use of the power storage device 6a of the EV 6 while further improving convenience for the user of the EV 6.

[0035] For example, if the parking time of EV6 overlaps with both a time period when power generation equipment 2 generates a lot of electricity and a time period when power generation equipment 2 generates a little electricity, and the charging rate information is set to less than 100%, control device 16 charges EV6's power storage device 6a at a rate higher than the target charging rate during the time period when power generation equipment 2 generates a lot of electricity, and then discharges EV6's power storage device 6a during the time period when power generation equipment 2 generates a little electricity, so that the charging rate reaches the target rate when EV6 ends parking.

[0036] For example, assume that EV 6 is parked from 9:00 to 18:00 and the target charge rate is set to 25%. In this case, control device 16 charges the power storage device 6a of EV 6 between 9:00 and 15:00, for example, to charge the power storage device 6a of EV 6 to a charge rate higher than 25%, and then discharges the power storage device 6a of EV 6 between 15:00 and 18:00, to set the charge rate of the power storage device 6a of EV 6 to 25%. This, for example, can further increase revenue from selling electricity and more effectively utilize the power storage device 6a of EV 6.

[0037] The charging rate does not necessarily have to be set to less than 100%. For example, before a holiday, it is possible to set the charging rate to 100% before going home. In this way, being able to arbitrarily set the target charging rate when parking ends can further enhance convenience for EV6 users.

[0038] Furthermore, the control device 16 acquires, for example, information regarding the dischargeable amount of the power storage device 6a that can be discharged within the parking time. The control device 16 acquires, for example, the information regarding the dischargeable amount by communicating with a plurality of charging / discharging stations 12 or information terminals, in the same manner as the information regarding the parking time and the charging rate. However, the method of acquiring the information regarding the dischargeable amount is not limited to the above and any method may be used.

[0039] The control device 16 determines the charge amount of the power storage device 6a and the discharge amount of the power storage device 6a based on the acquired information on the dischargeable amount.

[0040] Furthermore, the control device 16 acquires, for example, information regarding the chargeable amount of the power storage device 6a that is allowable within the parking time. The control device 16 acquires, for example, information regarding the chargeable amount by communicating with a plurality of charging / discharging stations 12 or information terminals, similar to the information regarding the parking time and the charging rate. However, the method of acquiring information regarding the chargeable amount is not limited to the above and any method may be used.

[0041] The control device 16 determines the charge amount of the power storage device 6a and the discharge amount of the power storage device 6a based on the acquired information on the chargeable amount. That is, the control device 16 determines the charge amount of the power storage device 6a and the discharge amount of the power storage device 6a based on the information on the dischargeable amount and the information on the chargeable amount. Note that the control device 16 does not necessarily need to acquire both the information on the dischargeable amount and the information on the chargeable amount. The control device 16 may acquire only one of the information on the dischargeable amount and the information on the chargeable amount, and determine the charge amount of the power storage device 6a and the discharge amount of the power storage device 6a based on the acquired information.

[0042] For example, suppose EV 6 is parked from 9:00 AM to 6:00 PM, the target charge rate is set to 25%, the allowable chargeable amount is set to 75% SOC, and the allowable dischargeable amount is set to 60% SOC. Furthermore, suppose the charge rate of power storage device 6a at the start of charging is 10% SOC. In this case, control device 16 charges power storage device 6a of EV 6 between 9:00 AM and 3:00 PM, charging power storage device 6a of EV 6 up to 85% SOC, and then discharges power storage device 6a of EV 6 between 3:00 PM and 6:00 PM, bringing the charge rate of power storage device 6a of EV 6 to 25%.

[0043] In this way, the allowable chargeable amount and dischargeable amount can be set arbitrarily. For example, a user who wants to set a high charge amount when returning home can set a high allowable chargeable amount. For example, a user who is concerned about deterioration of the power storage device 6a due to charging and discharging can set a low allowable dischargeable amount. By allowing the allowable chargeable amount and dischargeable amount to be set arbitrarily according to user preferences, the convenience of the EV 6 can be further improved.

[0044] The control device 16 can also acquire information regarding changes to the parking time of the EV 6. The control device 16 acquires information regarding changes to the parking time of the EV 6, for example, by communicating with multiple charging / discharging stations 12 or information terminals, similar to the information regarding the parking time and the charging rate. For example, when the user of the EV 6 wants to change the parking time due to an unexpected outing, the user operates an information terminal such as a smartphone owned by the user to send information regarding changes to the parking time of the EV 6 to the control device 16. However, the method of acquiring information regarding changes to the parking time of the EV 6 is not limited to the above and may be any method.

[0045] The control device 16 changes the parking time of the EV 6 in response to the acquired information regarding the change in the parking time. For example, if the current charge rate of the EV 6 differs from the target charge rate at the end of the parking time, the control device 16 charges or discharges the power storage device 6a of the EV 6 so that the target charge rate is reached at the end of the changed parking time. By making it possible to change the parking time of the EV 6 in this way, it is possible to prevent the charge rate of the EV 6 from differing from the desired charge rate, for example, when the user suddenly leaves the house. This can, for example, further improve convenience for the user of the EV 6.

[0046] When the control device 16 acquires information regarding a change in the parking time of EV 6 and finds that the charging rate of EV 6 is lower than the target charging rate, it performs one of the following as necessary, in order of highest priority, to achieve the target charging rate at the end of the changed parking period: charging the power storage device 6a using surplus power from the power generation equipment 2, charging the power storage device 6a using power stored in the power storage devices 6a of other dischargeable EVs 6 connected to multiple charging / discharging stands 12, stopping the charging of other EVs 6 connected to multiple charging / discharging stands 12, and charging the power storage device 6a using power from the power grid 4.

[0047] For example, if the time remaining until the end of the changed parking period is short, the control device 16 rapidly charges the power storage device 6a of the EV 6 whose parking period has been changed, based on the surplus power of the power generation facility 2, the power stored in the power storage devices 6a of the other EVs 6, and the power of the power grid 4. This makes it possible to further prevent the charge rate of the EV 6 from differing from the desired charge rate.

[0048] At this time, the control device 16 gives top priority to surplus power from the power generation facility 2 when charging the power storage device 6a of the EV 6 whose parking time has been changed. If the surplus power from the power generation facility 2 alone is insufficient, the control device 16 also uses power stored in the power storage devices 6a of the other EVs 6 to charge the power storage devices 6a of the EV 6 whose parking time has been changed. If the surplus power from the power generation facility 2 and the power stored in the power storage devices 6a of the other EVs 6 are insufficient, the control device 16 stops the charging of the other EVs 6 that can be stopped, thereby increasing the power available for charging the power storage devices 6a of the EV 6 whose parking time has been changed. If the surplus power from the power generation facility 2 and the power stored in the power storage devices 6a of the other EVs 6 are insufficient and there are no other EVs 6 whose charging can be stopped, the control device 16 also uses power from the power grid 4 to charge the power storage devices 6a of the EV 6 whose parking time has been changed.

[0049] In this way, in descending order of priority, one of the following is performed as needed: charging the power storage device 6a using surplus power from the power generation facility 2; charging the power storage device 6a using power stored in the power storage devices 6a of other dischargeable EVs 6 connected to multiple charging / discharging stands 12; stopping the charging of other EVs 6 connected to multiple charging / discharging stands 12; and charging the power storage device 6a using power from the power grid 4. By giving priority to using surplus power from the power generation facility 2 and power stored in the power storage devices 6a of other EVs 6 in this way, it is possible to reduce the amount of power used from the power grid 4 even when charging the power storage device 6a of an EV 6 whose parking time has been changed. For example, it is possible to reduce the contract demand fee associated with the use of power from the power grid 4.

[0050] FIG. 2 is a block diagram schematically illustrating a modified example of the EV charging / discharging system according to the embodiment. 2, in the EV charging / discharging system 10a, the multiple bidirectional AC / DC converters 14 are replaced with multiple bidirectional DC / DC converters 20 (bidirectional converters). The EV charging / discharging system 10a further includes a bidirectional AC / DC converter 22.

[0051] The bidirectional AC / DC converter 22 converts AC power supplied from the power grid 4 into DC power, and also converts the DC power into AC power according to the power grid 4, and supplies the converted AC power to the power grid 4.

[0052] The multiple bidirectional DC / DC converters 20 are provided corresponding to the multiple charging / discharging stands 12, respectively, and perform bidirectional power conversion in a direction to charge the power storage device 6 a of the EV 6 connected to the corresponding charging / discharging stand 12, and in a direction to discharge the power storage device 6 a of the EV 6 connected to the corresponding charging / discharging stand 12.

[0053] The bidirectional DC / DC converter 20 converts DC power supplied from at least one of the power generation facility 2 and the power grid 4 and converted by the bidirectional AC / DC converter 22 into another DC power compatible with the EV 6, and supplies the converted DC power to the corresponding charging / discharging stand 12. The bidirectional DC / DC converter 20 also converts DC power supplied from the power storage device 6a of the EV 6 connected to the corresponding charging / discharging stand 12 into DC power compatible with the bidirectional AC / DC converter 22, and supplies the converted DC power to the bidirectional AC / DC converter 22. The bidirectional AC / DC converter 22 converts the DC power supplied from the multiple bidirectional DC / DC converters 20 into AC power compatible with the power grid 4.

[0054] In this way, in power conversion in the charging direction, the multiple bidirectional DC / DC converters 20 convert power supplied from at least one of the power generation facility 2 and the power grid 4 into DC power compatible with the EVs 6, and supply the converted DC power to the corresponding charging / discharging stands 12. In power conversion in the discharging direction, the multiple bidirectional DC / DC converters 20 convert DC power supplied from the power storage device 6a of the EVs 6 connected to the corresponding charging / discharging stands 12 into DC power on the bidirectional AC / DC converter 22 side (power grid 4 side), and supply the converted power to the bidirectional AC / DC converter 22 side.

[0055] As a result, the multiple bidirectional DC / DC converters 20 can supply converted DC power to the bidirectional AC / DC converter 22 and also to other bidirectional DC / DC converters 20. In other words, the multiple bidirectional DC / DC converters 20 enable selling of power (reverse power flow) to the power grid 4 based on the power stored in the power storage device 6a of the EV 6, and also enable charging of the power storage device 6a of another EV 6 based on the power stored in the power storage device 6a of the EV 6. The bidirectional DC / DC converter 20 is, for example, a DC / DC converter capable of bidirectional power conversion.

[0056] The control device 16 controls the operation of the multiple bidirectional DC / DC converters 20 and also controls the operation of the bidirectional AC / DC converter 22. The control device 16 controls the direction of power conversion by the bidirectional AC / DC converter 22 and the magnitude of the converted power, depending on the total power in the charging and discharging directions of the multiple bidirectional DC / DC converters 20. As a result, the operation of the bidirectional AC / DC converter 22 makes it possible to supply power supplied from at least one of the power generation facility 2 and the power grid 4 to the multiple bidirectional DC / DC converters 20, and to sell power (reverse power flow) to the power grid 4 based on the power stored in the power storage device 6a of the EV 6.

[0057] In this way, the multiple bidirectional converters may be bidirectional AC / DC converters 14 or bidirectional DC / DC converters 20. The supply of power from one bidirectional converter to another bidirectional converter (the supply of power from an EV 6 to another EV 6) may be AC ​​power or DC power. The configuration of the multiple bidirectional converters is not limited to the above and may be any configuration that is provided corresponding to each of the multiple charging and discharging stands 12 and that can perform bidirectional power conversion in both directions: charging the power storage device 6a of the EV 6 connected to the corresponding charging and discharging stand 12, and discharging the power storage device 6a of the EV 6 connected to the corresponding charging and discharging stand 12.

[0058] The present embodiment includes the following aspects. (Appendix 1) An EV charging / discharging system connected to a power generation facility that uses renewable energy and a power grid, a plurality of charging / discharging stations that are detachably connected to EVs to charge and discharge power storage devices mounted on the connected EVs; a plurality of bidirectional converters provided corresponding to the plurality of charging / discharging stands, each of which performs bidirectional power conversion in a direction to charge the power storage device of the EV connected to the corresponding charging / discharging stand and a direction to discharge the power storage device of the EV connected to the corresponding charging / discharging stand; a control device for controlling the operation of the plurality of bidirectional converters; Equipped with In the power conversion in the charging direction, the plurality of bidirectional converters convert power supplied from at least one of the power generation facility and the power grid into DC power compatible with the EV and supply the converted DC power to the corresponding charging / discharging stand, and in the power conversion in the discharging direction, convert DC power supplied from the power storage device of the EV connected to the corresponding charging / discharging stand into power on the power grid side and supply the converted power to the power grid side; The control device acquires information about parking times of the EVs connected to the multiple charging / discharging stations and information about target charging rates at the end of parking of the EVs connected to the multiple charging / discharging stations, and, based on the acquired parking time information and charging rate information, controls operation of the multiple bidirectional converters in the charging direction during time periods when the power generation facility has a high amount of power, and controls operation of the multiple bidirectional converters in the discharging direction during time periods when the power generation facility has a low amount of power, so that the EVs connected to each of the multiple charging / discharging stations will have the target charging rate at the end of parking.

[0059] (Appendix 2) 2. The EV charging / discharging system according to claim 1, wherein, when a parking period of the EV overlaps with both a time period when the power generation facility has high power generation and a time period when the power generation facility has low power generation and the information on the charge rate is set to less than 100%, the control device charges the power storage device of the EV at a rate higher than a target charge rate during the time period when the power generation facility has high power generation, and then discharges the power storage device of the EV during the time period when the power generation facility has low power generation so that the charge rate will be the target rate when the EV ends parking.

[0060] (Appendix 3) The control device acquires information about an allowable discharge amount of the power storage device within a parking time, and determines a charge amount of the power storage device and a discharge amount of the power storage device based on the acquired information about the allowable discharge amount.

[0061] (Appendix 4) The EV charging / discharging system according to claim 2 or 3, wherein the control device acquires information about an allowable chargeable amount of the power storage device within a parking time, and determines a charge amount and a discharge amount of the power storage device based on the acquired information about the chargeable amount.

[0062] (Appendix 5) The EV charging / discharging system according to any one of appendices 1 to 4, wherein the control device is capable of acquiring information regarding changes to the parking time of the EV, and performs processing to change the parking time in response to the acquisition of information regarding changes to the parking time of the EV.

[0063] (Appendix 6) The EV charging / discharging system according to claim 5, wherein when the control device acquires information related to a change in the parking time of the EV and finds that the charging rate of the EV is lower than a target charging rate, the control device performs one of the following as necessary, in descending order of priority, to achieve the target charging rate at the end of the changed parking period: charging the power storage device using surplus power from the power generation facility; charging the power storage device using power stored in the power storage devices of other EVs that are connected to the multiple charging / discharging stands and that are capable of discharging; stopping charging of the other EVs connected to the multiple charging / discharging stands; and charging the power storage device using power from the power grid.

[0064] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0065] 2...power generation equipment, 4...power system, 6...EV (electric vehicle), 6a...electric storage device, 10, 10a...EV charging / discharging system, 12...charging / discharging stand, 14...bidirectional AC / DC converter, 16...control device, 20...bidirectional DC / DC converter, 22...bidirectional AC / DC converter

Claims

1. An EV charging / discharging system connected to a power generation facility that uses renewable energy and a power grid, a plurality of charging / discharging stands that are detachably connected to EVs to charge and discharge power storage devices mounted on the connected EVs; a plurality of bidirectional converters provided corresponding to the plurality of charging / discharging stands, each of which performs bidirectional power conversion in a direction to charge the power storage device of the EV connected to the corresponding charging / discharging stand and a direction to discharge the power storage device of the EV connected to the corresponding charging / discharging stand; a control device for controlling the operation of the plurality of bidirectional converters; Equipped with In the power conversion in the charging direction, the plurality of bidirectional converters convert power supplied from at least one of the power generation facility and the power grid into DC power compatible with the EV and supply the converted DC power to the corresponding charging / discharging stand, and in the power conversion in the discharging direction, convert DC power supplied from the power storage device of the EV connected to the corresponding charging / discharging stand into power on the power grid side and supply the converted power to the power grid side; the control device acquires information on parking times of the EVs connected to the plurality of charging / discharging stations and information on target charging rates at the end of parking of the EVs connected to the plurality of charging / discharging stations, and controls, based on the acquired parking time information and charging rate information, operation of the plurality of bidirectional converters in the charging direction during time periods when the amount of power generation by the power generation facility is high, and controls operation of the plurality of bidirectional converters in the discharging direction during time periods when the amount of power generation by the power generation facility is low, so that the EVs connected to each of the plurality of charging / discharging stations will have the target charging rates at the end of parking; The control device is capable of acquiring information regarding changes to the parking time of the EV, and processes the change in parking time in response to the acquisition of the information regarding the change in parking time of the EV. If the charging rate of the EV is lower than a target charging rate when the information regarding the change in parking time of the EV is acquired, the control device performs one of the following as necessary, in descending order of priority, so that the charging rate of the EV will reach the target charging rate at the end of the changed parking period: charging the power storage device using surplus power from the power generation equipment, charging the power storage device using power stored in the power storage devices of other EVs that are connected to the multiple charging / discharging stands and that can be discharged, stopping the charging of the other EVs connected to the multiple charging / discharging stands, or charging the power storage device using power from the power grid.

2. 2. The EV charging / discharging system according to claim 1, wherein, when a parking period of the EV overlaps with both a time period during which the power generation facility generates a large amount of power and a time period during which the power generation facility generates a small amount of power, and the charge rate information is set to less than 100%, the control device charges the power storage device of the EV to a charge rate higher than a target charge rate during the time period during which the power generation facility generates a large amount of power, and then discharges the power storage device of the EV during the time period during which the power generation facility generates a small amount of power, so that the charge rate reaches the target charge rate when the EV ends parking.

3. 3. The EV charging / discharging system according to claim 2, wherein the control device acquires information about an allowable discharge amount of the power storage device within a parking time, and determines a charge amount of the power storage device and a discharge amount of the power storage device based on the acquired information about the allowable discharge amount.

4. 3. The EV charging / discharging system according to claim 2, wherein the control device acquires information about an allowable chargeable amount of the power storage device within a parking time, and determines a charge amount and a discharge amount of the power storage device based on the acquired information about the allowable chargeable amount.

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