Charging and discharging system

Abstract

To provide a charging and discharging system that can select either a rapid charging or a normal charging, which is slower than the rapid charging, for the storage batteries of a plurality of electric vehicles, at low cost.SOLUTION: In the charging and discharging system having a plurality of charging and discharging stands, the charging and discharging system is configured at low cost by limiting the number of the charging and discharging stands capable of performing the rapid charging. A first power supply line SL11 or SL12 and a first direct current relay R11 or R12, which are used in a supply direct current connection circuit that supplies combined direct current power obtained by combining direct current power output from n charging and discharging power supply circuits PS1 to PS5 in a single charging operation to a specific charging and discharging stand S1 for the rapid charging, are configured by expensive components required for the rapid charging. Power supply lines SL13 to SL15 and direct current relays R13 to R15, which are used in circuit portions connected to the other charging and discharging stands S3 to S5, are configured by inexpensive components.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charging / discharging system having a plurality of charging / discharging power supply circuits capable of performing a charging operation to charge a storage battery of an electric vehicle and a discharging operation to supply power from the storage battery to a load electrically connected to a power receiving facility. [Background technology]

[0002] Japanese Patent No. 7315739 (Patent Document 1) discloses a charging / discharging system including a power receiving facility that supplies and demands power from a power transmission system, a plurality of battery cells mounted on each of a plurality of electric vehicles, and a plurality of chargers / dischargers that perform a charging operation to charge the plurality of battery cells using charging power received by the power receiving facility, and a discharging operation to supply power from the plurality of battery cells to loads electrically connected to the power receiving facility. The charging / discharging system shown in Patent Document 1 is used in a facility run by a business that has a parking lot and charging facilities for a plurality of electric vehicles.

[0003] Furthermore, Japanese Patent Publication No. 62-58227 (Patent Document 2) discloses a charging system for electric vehicles, which is a charging device equipped with a plurality of chargers for charging storage batteries mounted on each of a plurality of electric vehicles, and which includes connection means for initially connecting the output terminals of a certain number of the plurality of chargers in parallel to rapidly charge one of the plurality of storage batteries, and switching means for switching the parallel connection of the output terminals of the storage batteries according to the charging state of the storage battery to which the connection means is connected, thereby increasing or decreasing the number of chargers connected in parallel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7315739 [Patent Document 2] Special Publication No. 62-58227 Summary of the Invention [Problem to be solved by the invention]

[0005] The charging system disclosed in Patent Document 2 discloses a multi-configuration that allows the user to select between rapid charging (large-capacity charging) and normal charging (small-capacity charging) for the storage battery. It is possible to apply the system disclosed in Patent Document 2 to a charging / discharging system like that disclosed in Patent Document 1. However, in reality, the adoption of such charging / discharging systems has not progressed as expected. The reason for this is that the cost of equipment becomes extremely high as the number of EVs increases. This is because businesses that use EVs for business purposes typically use normal charging, but may need rapid charging for business reasons. Therefore, they often install rapid chargers (approximately 30 kW to 50 kW) in addition to normal chargers (approximately 10 kW or less), which can result in high equipment costs. Therefore, if this configuration could be achieved with a single device, the utilization rate of the charging infrastructure would increase, creating cost benefits.

[0006] The object of the present invention is to provide an inexpensive multi-charging / discharging system that can select either rapid charging (large capacity charging) or normal charging (small capacity charging), which is slower than rapid charging, for the storage batteries of multiple electric vehicles. [Means for solving the problem]

[0007] In the following, for ease of understanding, the configuration of the present invention will be described using the reference numerals attached to the drawings. Note that the reference numerals attached in the following description do not limit the present invention to the embodiments.

[0008] A charging / discharging system 1 according to a first aspect of the present invention includes a power receiving equipment PR that supplies and demands electric power from a commercial power source, and n parallel-connected charging / discharging power supply circuits PS1 to PS5 that perform a charging operation of charging at least one of n electric storage devices B1 to B5 mounted on each of n electric vehicles EV1 to EV5 (n is an integer of 3 or greater) using charging power received by the power receiving equipment PR, and a discharging operation of supplying power from at least one of the n electric storage devices B1 to B5 to a load L electrically connected to the power receiving equipment PR.

[0009] Furthermore, the charging / discharging system 1 of the first aspect of the present invention includes n charging / discharging stations S1 to S5 each having a connector C connecting the n charging / discharging power supply circuits PS1 to PS5 with n battery cells B of n electric vehicles, n DC connecting circuits DC1 to DC5 each including first power supply lines SL11 to SL15 and first DC relays R11 to R15 and arranged between the n charging / discharging stations S1 to S5 and the n charging / discharging power supply circuits PS1 to PS5, respectively, and n-1 inter-terminal connecting circuits TC1 to TC4 each including second power supply lines SL21 to SL24 and second DC relays R21 to R24 and arranged between two DC terminals of the n DC terminals DT1 to DT5 to connect two adjacent terminals of the n DC terminals DT1 to DT5 of the n charging / discharging power supply circuits PS1 to PS5. Furthermore, the charging / discharging system 1 has n-1 inter-terminal connection circuits TC1-TC4 including second power supply lines SL21-SL24 and second DC relays R21-R24 arranged between two adjacent DC terminals to interconnect the n DC terminals DT1-DT5 of the n charging / discharging power supply circuits PS1-PS5 to form a closed loop circuit, and one inter-terminal connection circuit TC5 including a second power supply line SL25 and a second DC relay R25 arranged between the two DC terminals DT1 and DT5 located at both ends.The charging / discharging system 1 also has a control unit CD that controls switching of the charging / discharging operation of the plurality of charging / discharging power supply circuits PS1-PS5 and switching of the opening / closing operation of the plurality of first DC relays R11-R15 and the plurality of second DC relays R21-R25.

[0010] The control unit CD controls the opening and closing of first DC relays R11 to R15 and n second DC relays R21 to R25 so that all of the composite DC power output from n charging / discharging power supply circuits PS1 to PS5 can be supplied to m specific charging / discharging stands S1 for rapid charging connected to m (m is an integer greater than or equal to 1 and less than n) DC connection circuits DC1.

[0011] The first power supply line and the first DC relay included in m DC connection circuits of the n DC connection circuits DC1 to DC5 each have an installed capacity required to supply composite DC power, which is the DC power output from the n charge / discharge power supply circuits PS1 to PS5 in one charging, to the electric vehicle's battery connected to the connector C of one specific fast charging / discharging stand selected by the control unit CD from the m specific fast charging / discharging stands connected to the m DC connection circuits.

[0012] Furthermore, other components, including the nm first feed lines and nm first DC relays, the n-1 second feed lines SL21 to SL24 and the n-1 second DC relays R21 to R24, and the closed loop forming second feed line SL25 and the closed loop forming second DC relay R25, included in the nm DC connection circuits other than the m DC connection circuits, each have an installed capacity required to supply a small amount of power that is less than the combined DC power to the nm DC connection circuits.

[0013] Furthermore, when one specific charging / discharging stand for rapid charging is selected, the control unit CD controls the opening and closing of n first DC relays and n-1 second DC relays R21 to R24, as well as the second DC relay R25 for forming a closed loop, so that small power is not supplied to the DC connection circuits of charging / discharging stands other than the specific charging / discharging stand.

[0014] When a specific charging / discharging station for rapid charging is not selected, the opening and closing of n first DC relays and n-1 second DC relays R21 to R24, as well as the second DC relay R25 for forming a closed loop, are controlled so that a small amount of power is supplied to the DC connection circuit of each charging / discharging station.

[0015] To reduce costs, it is usually preferable to configure the system with a number of circuits where m is 1 or at most less than n / 2. For example, when n is 5 and m is 2, the small power is 1 / 5 to 3 / 5 of the combined DC power.

[0016] By using the configuration of the charging / discharging system 1 of the first aspect of the present invention and using appropriately rated components, EV1 to EV5 connected to n charging / discharging stations S1 to S5 can be normally charged using the DC output of the corresponding n charging / discharging power supply circuits PS1 to PS5 (the charging capacity at this time is equal to or greater than the rated capacity of one charging / discharging power supply circuit but less than the total amount for n stations), and in addition, m (m is an integer greater than 1 and less than n) charging / discharging stations S1 out of the n charging / discharging stations can be operated as specific charging / discharging stations capable of rapid charging (the charging capacity at this time is the total amount of n times the rated capacity of one charging / discharging power supply circuit), making it possible to build a highly convenient charging / discharging system 1 at a lower cost than conventional systems.

[0017] In the case where the charging / discharging system 1 of the first aspect is used and a specific charging / discharging stand S1 capable of rapid charging m units is installed among the n DC connection circuits DC1 to DC5, the first power supply line and the first DC relay included in the m DC connection circuits may each have an installation capacity required for rapid charging (large-capacity charging) of the combined DC power obtained by combining the DC outputs of the n charging / discharging power supply circuits in one charging to the storage battery of an electric vehicle connected to the connector of one specific charging / discharging stand for rapid charging connected to one DC connection circuit.

[0018] Furthermore, among the second power supply lines SL21 to SL25 and second DC relays R21 to R25 included in each of the n inter-terminal connection circuits TC1 to TC5, the components involved in power supply to the m specific charging / discharging stations S1 may each have the minimum equipment capacity required for rapid charging.

[0019] Furthermore, among the second power supply lines SL21 to SL25 and second DC relays R21 to R25 included in each of the n inter-terminal connection circuits TC1 to TC5, the components not involved in the power supply to m specific charging / discharging stands S1, and the first power supply lines (SL12 to SL15) and first DC relays (R12 to 15) included in each of the n-m DC connection circuits other than the m DC connection circuit DC1, may each have the minimum installed capacity required for normal charging (small-capacity charging) of the storage battery (B2 to B5) of one electric vehicle (EV2 to EV5) connected to one charging / discharging stand (S2 to S5) using the combined DC output output from at least one but less than n charging / discharging power supply circuits (PS1 to PS5) in one charging.

[0020] By using the configuration of the charging / discharging system 1 of the first aspect of the present invention and using appropriately rated components, only m specific charging / discharging stations for rapid charging can perform rapid charging (large-capacity charging) of the storage battery B1 with the combined DC power (the charging capacity at this time is the total amount of n times the rated capacity of one charging / discharging power supply circuit) that is the DC power output from n charging / discharging power supply circuits PS1 to PS5 in one charging, and the other charging / discharging stations S2 to S5 can perform normal charging (small-capacity charging), which is slower than rapid charging.

[0021] Therefore, for example, the first power supply line and first DC relay used in the circuit portion connected to m specific charging / discharging stations for rapid charging can be configured with high-capacity, expensive components required for rapid charging (high-capacity charging), while the first power supply line and first DC relay used in the circuit portion connected to the other charging / discharging stations and the second power supply line and second DC relay included in the terminal connection circuit can be configured with inexpensive components with a capacity roughly less than half that of the high-capacity, expensive components.As a result, compared to applying the multiple charging system shown in Patent Document 2 to the charging / discharging system described in Patent Document 1, the present invention can achieve the effect of significantly reducing equipment costs.

[0022] The second embodiment of the charging / discharging system 11 of the present invention is a modified example of the first embodiment of the charging / discharging system 1, and when n is an odd number greater than or equal to 3, the number of specific charging / discharging stands S1 for rapid charging is set to one, and the installation location is changed to, for example, a central position, thereby making it possible to reduce the amount of expensive, large-capacity parts used compared to the charging / discharging stand of the first embodiment.

[0023] That is, in this embodiment, n charge / discharge power supply circuits PS1 to PS5 connected in parallel are used, which perform a charging operation of charging at least one of n battery storage devices B1 to B5 mounted on each of n or more odd-numbered electric vehicles EV1 to EV5 using charging power received by the power receiving equipment PR, and a discharging operation of supplying power from at least one of the n battery storage devices B1 to B5 to a load L electrically connected to the power receiving equipment PR. The first power feed line SL13 and the first DC relay R13 included in one DC connection circuit (DC3) of the n DC connection circuits DC1 to DC5 each have an installation capacity required to supply combined DC power output from the n charge / discharge power supply circuits PS1 to PS5 in one charging to the battery (B3) of the electric vehicle (EV3) connected to the connector C of a specific rapid charging / discharging stand (S3) connected to the one DC connection circuit (DC3).

[0024] The other components, including the n-1 first power feed lines and n-1 first DC relays, as well as the n-1 second power feed lines SL21-SL24 and the n-1 second DC relays R21-R24, included in the n-1 DC connection circuits other than one DC connection circuit, each have a minimum installed capacity required to supply small power that is less than the combined DC power. When a specific charging / discharging stand for quick charging is selected, the control unit CD controls the opening and closing of the n first DC relays and the n-1 second DC relays R21-R24 so that small power is not supplied to the DC connection circuits of charging / discharging stands other than the specific charging / discharging stand.

[0025] In this way, one charging / discharging stand S3 can be configured to be capable of large-capacity charging, and moreover, the amount of large-capacity, expensive parts used can be reduced compared to the first embodiment.

[0026] The control unit CD controls the n-1 first power feed lines and the n-1 first DC relays, as well as the n-1 second power feed lines SL21-SL24 and the n-1 second DC relays R21-R24 included in the n-1 DC connection circuits other than the one DC connection circuit, to supply a small amount of power that is less than the composite DC power output from the n charging / discharging power supply circuits PS1-PS5 to the charging / discharging stand S3 connected to the one DC connection circuit DC3, and when a specific charging / discharging stand for fast charging is selected, the control unit CD controls the opening and closing of the n first DC relays and the n-1 second DC relays R21-R24 so that the small amount of power is not supplied to the DC connection circuits of charging / discharging stands other than the specific charging / discharging stand.

[0027] When n is 5, the first power feed line SL13 and the first DC relay R13 included in the DC connection circuit DC3 located at the center of the n DC connection circuits DC1 to DC5 only need to have an installed capacity sufficient to supply composite DC power, which is the sum of the DC power output from the n charge / discharge power supply circuits PS1 to PS5 in one charging, to the battery B3 of the electric vehicle EV3 connected to the connector C of the specific charge / discharge stand S3 for rapid charging connected to the single DC connection circuit DC3. The small power is preferably 1 / 5 or less of the composite DC power. When n is 3, the small power is preferably 1 / 3 or less of the composite DC power.

[0028] A charging / discharging system 12 according to a third embodiment of the present invention is a modified version of the charging / discharging system 11 according to the second embodiment. This charging / discharging system is intended for installation in a small space in a small business. The number of charging / discharging stations n is set to a minimum of three, and the number of specific charging / discharging stations S1 for rapid charging is set to one. Furthermore, the specific charging / discharging station S1 is installed in a central location, making the system more compact than the charging / discharging stations according to the second embodiment. However, compared to the first and second embodiments, the charging / discharging system 12 according to the third embodiment has only three charging / discharging stations S1 to S3, which reduces user convenience. Therefore, to increase the number of EVs that can be connected simultaneously, each of the three charging / discharging stations S1 to S3 may be provided with a plurality of connectors C, and the three charging / discharging stations and the control unit CD may be configured to continuously charge the storage batteries of multiple electric vehicles using a single charging / discharging station. In this way, after charging of the battery B of one electric vehicle EV is completed, charging of the battery B' of the second electric vehicle EV' starts consecutively without the need for manual reconnection of the charging plug. In this way, when charging of one side is completed, charging of the other side starts automatically, eliminating the need to wait for charging of one side to be completed, thereby improving convenience for the user.

[0029] A combined charging / discharging system may be configured by connecting a plurality of charging / discharging units in parallel to a charging facility PR, each of which is configured by components other than the charging / discharging systems of any one of the first to third aspects described above, excluding the charging / discharging stands. In such a combined charging / discharging system, the system can be easily expanded by adding more charging / discharging units.

[0030] Multiple charging / discharging units may be mounted on one or more utility poles. In this case, multiple charging / discharging stands may be mounted on multiple utility poles, respectively. This further reduces the installation space for the system. [Brief explanation of the drawings]

[0031] [Figure 1]1 is a block diagram showing the configuration of a charge / discharge system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a situation in which normal charging is being performed at all charging / discharging stations in a configuration in which two specific charging / discharging stations capable of rapid charging are used, using the charging / discharging system of the first aspect of FIG. 1. [Figure 3] FIG. 3 is a diagram showing a situation when one of the charging / discharging stations for rapid charging is switched to rapid charging from the situation in FIG. 2. [Figure 4] This figure shows the situation when, from the situation in Figure 3, charging of the first electric vehicle's battery is completed through rapid charging at one specific charging / discharging station, charging is stopped, and then another specific charging / discharging station is switched to rapid charging. [Figure 5] This figure shows the situation from Figure 4 when another specific charging / discharging station has completed charging the second electric vehicle's battery through rapid charging and stopped charging, and the remaining other charging / discharging stations have resumed normal charging. [Figure 6] FIG. 2 is a block diagram showing the configuration of a charge / discharge system according to a second embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing an example in which the charging / discharging system of the second embodiment of FIG. 6 is used, and a charging / discharging stand located in a central position is used as a specific charging / discharging stand capable of rapid charging. [Figure 8] FIG. 10 is a block diagram showing the basic configuration of a charge / discharge system 12 according to a third embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing an example of the configuration of a combined charge / discharge system in which two charge / discharge systems 12 according to a third embodiment of the present invention are connected in parallel. [Figure 10] FIG. 10 is a diagram showing an example of a configuration in which the combined charge / discharge system of FIG. 9 is mounted on a utility pole. DETAILED DESCRIPTION OF THE INVENTION

[0032] Specific examples of embodiments of the charge / discharge systems according to the first to third aspects of the present invention will be described in detail below with reference to the drawings.

[0033] [Charge / Discharge System of First Aspect] FIG. 1 shows the basic configuration of an embodiment in which a charging / discharging system 1 according to a first aspect of the present invention is applied to a dedicated parking lot. FIG. 2 shows an example in which two charging / discharging stations capable of rapid charging and three charging / discharging stations capable of only normal charging are mixed using the basic configuration of FIG. 1. FIG. 3 shows an example in which rapid charging is performed at one charging / discharging station S1 and charging is not performed at the other charging / discharging stations S2 to S5 in the example in FIG. 2. FIG. 4 shows an example in which rapid charging is performed at one charging / discharging station S2 and charging is not performed at the other charging / discharging stations S1, S3 to S5 in the example in FIG. 2. FIG. 5 shows an example in which charging is not performed at two charging / discharging stations S1 and S2 in the example in FIG. 2 and charging is performed at low power at the other charging / discharging stations S3 to S5.

[0034] In the charging / discharging system 1 according to the first embodiment shown in FIGS. 1 to 5, a charging / discharging unit U connected to a power receiving facility PR that receives and supplies power from a commercial power source is configured in a single housing, and this housing is installed within a dedicated parking lot or on a utility pole. The charging / discharging unit U is equipped with five charging / discharging power supply circuits PS1 to PS5, each with a rated capacity of 10 kW, for a total power supply capacity of 50 kW. Furthermore, five charging / discharging stations S1 to S5 corresponding to the five charging / discharging power supply circuits PS1 to PS5 are installed at predetermined intervals within the same parking lot. In this embodiment, two charging / discharging stations S1 and S2 are designated as specific charging / discharging stations capable of rapid charging, each with an installed capacity capable of rapid charging of up to 50 kW. The other charging / discharging stations S3 to S5 have an installed capacity capable of normal charging of up to 20 kW.

[0035] The first aspect of Fig. 2 to Fig. 5 will be described below. To accommodate a maximum output of 50 kW, components with an installed capacity of 50 kW are used for the first power feed lines SL11 and SL12 and the first DC relays R11 and R12 in the two DC connection circuits DC1 to DC2 connected to the specific fast charging charge / discharge stations S1 and S2. Note that in Fig. 2 to Fig. 5, differences in installed capacity are indicated by bold lines. Components with an installed capacity of 20 kW are used for the first power feed lines SL13 to SL15 and the first DC relays R13 to R15 in the three DC connection circuits DC3 to DC5 connected to the other charge / discharge stations S3 to S5, and for the second power feed lines SL21 to SL25 and the second DC relays R21 to R25 in the five terminal connection circuits TC1 to TC5.

[0036] In the first embodiment shown in FIGS. 2 to 5, which uses components with such installed capacities, only two specific rapid-charging charging / discharging stations S1 and S2 can rapidly charge (large-capacity charge) the battery B1 or B2 with the combined DC power (50 kW rapid-charging power) output from the five charging / discharging power supply circuits PS1 to PS5 in a single charge. The other charging / discharging stations S3 to S5 use components with a rated capacity of 20 kW instead of the 10 kW capacity of the corresponding charging / discharging power supply circuits. Therefore, if there is available space in the charging / discharging power supply circuits, these can be used to perform normal charging at up to 20 kW at the other charging / discharging stations. Note that this embodiment is applied to a dedicated parking lot, and so as long as users are informed in advance of the features of this charging / discharging system 1, which includes a mixture of charging / discharging stations capable of rapid charging and charging / discharging stations capable of only normal charging, some inconvenience to users will not be a problem.

[0037] In the embodiment of the first aspect shown in Figures 2 to 5, in order to charge the battery cells B1 to B5 mounted on five electric vehicles EV1 to EV5 from five charging and discharging stations S1 to S5, five charging and discharging power supply circuits PS1 to PS5 are provided which perform a charging operation of charging at least one of the five battery cells B1 to B5 using charging power received by the power receiving equipment PR, and a discharging operation of supplying power from at least one of the five battery cells B1 to B5 to a load L electrically connected to the power receiving equipment PR.

[0038] In addition, in an embodiment of the first aspect, there are provided five inter-terminal connection circuits TC1 to TC5, each including second power supply lines SL21 to SL25 and second DC relays R21 to R25, arranged between two of the five DC terminals DT1 to DT5, in order to interconnect the five DC terminals DT1 to DT5 of the five charge / discharge power supply circuits PS1 to PS5. In order to interconnect the five DC terminals DT1 to DT5 of the five charge / discharge power supply circuits PS1 to PS5 and form a closed loop circuit LC, there are provided four inter-terminal connection circuits TC1 to TC4, each including second power supply lines SL21 to SL24 and second DC relays R21 to R24, arranged between two adjacent DC terminals, and one closed loop-forming inter-terminal connection circuit TC5, which is arranged between the two DC terminals DT1 and DT5 located at both ends and includes a closed loop-forming second power supply line SL25 and a closed loop-forming second DC relay R25.

[0039] The five charge / discharge power supply circuits PS1 to PS5 are respectively equipped with charge / discharge control boards SB1 to SB5 that control the charge / discharge power supply circuits PS1 to PS5 to perform charge / discharge operations in response to control signals from the control unit CD.

[0040] Each of the five charging / discharging stations S1 to S5 has a connector C that connects the five charging / discharging power supply circuits PS1 to PS5 with the five battery cells B1 to B5 of the five electric vehicles. Five DC connection circuits DC1 to DC5, each including first power feed lines SL11 to SL15 and first DC relays R11 to R15, are connected between the n charging / discharging stations S1 to S5 and the n charging / discharging power supply circuits PS1 to PS5. Each of the five charging / discharging stations S1 to S5 is equipped with a touch display DP1 to DP5 that includes operation buttons for each charging / discharging station S1 to S5 and a display that displays the operating status.

[0041] The control unit CD has the functions of receiving a charge start command via operation of the touch buttons on the touch displays DP1 to DP5, receiving information from the charge / discharge control boards SB1 to SB5 including the operating status of the charge / discharge power supply circuits PS1 to PS5, and receiving the open / close status of the first DC relays R11 to R15 and the second DC relays R21 to R25. The control unit CD also has the functions of sending information on the charge capacity that can be charged to the charge / discharge control boards SB1 to SB5 and sending open / close commands to the first DC relays R11 to R15 and the second DC relays R21 to R25, taking into account the operating status of the charge / discharge power supply circuits PS1 to PS5 and the open / close status of the first DC relays R11 to R15 and the second DC relays R21 to R25.

[0042] 1 to 5 can be abstracted and explained as follows using n (an integer of 3 or more) and m (an integer of 1 or more and less than n): The charging / discharging system 1 of the first embodiment includes a power receiving facility PR that supplies and demands power from a commercial power source, and n charging / discharging power supply circuits PS1 to PS5 connected in parallel that perform a charging operation of charging at least one of n power storage devices B1 to B5 mounted on each of n electric vehicles EV1 to EV5 (n is an integer of 3 or more), using charging power received by the power receiving facility PR, and a discharging operation of supplying power from at least one of the n power storage devices B1 to B5 to a load L electrically connected to the power receiving facility PR. The charging / discharging system 1 includes n charging / discharging stations S1 to S5 each having a connector C that connects the n charging / discharging power supply circuits PS1 to PS5 with n battery cells B of n electric vehicles; n DC connection circuits DC1 to DC5 each including first power supply lines SL11 to SL15 and first DC relays R11 to R15 and arranged between the n charging / discharging stations S1 to S5 and the n charging / discharging power supply circuits PS1 to PS5; and n-1 inter-terminal connection circuits TC1 to TC4 each including second power supply lines SL21 to SL24 and second DC relays R21 to R24 and arranged between two DC terminals of the n DC terminals DT1 to DT5 to connect two adjacent terminals of the n DC terminals DT1 to DT5 of the n charging / discharging power supply circuits PS1 to PS5. Furthermore, the charge / discharge system 1 includes n-1 inter-terminal connection circuits TC1 to TC4 each including second power supply lines SL21 to SL24 and second DC relays R21 to R24 arranged between two adjacent DC terminals to interconnect the n DC terminals DT1 to DT5 of the n charge / discharge power supply circuits PS1 to PS5 to form a closed loop circuit, and one inter-terminal connection circuit TC5 including a second power supply line SL25 and a second DC relay R25 arranged between the two DC terminals DT1 and DT5 located at both ends.The charge / discharge system 1 also includes a control unit CD that controls switching of the charge / discharge operation of the plurality of charge / discharge power supply circuits PS1 to PS5 and switching of the opening / closing operation of the plurality of first DC relays R11 to R15 and the plurality of second DC relays R21 to R25.

[0043] The control unit CD controls the opening and closing of first DC relays R11 to R15 and n second DC relays R21 to R25 so that all of the composite DC power output from n charging / discharging power supply circuits PS1 to PS5 can be supplied to m specific charging / discharging stands S1 for rapid charging connected to m (m is an integer greater than or equal to 1 and less than n) DC connection circuits DC1.

[0044] The first power supply line and the first DC relay included in m DC connection circuits of the n DC connection circuits DC1 to DC5 each have an installed capacity required to supply composite DC power, which is the DC power output from the n charge / discharge power supply circuits PS1 to PS5 in one charging, to a battery of an electric vehicle connected to the connector C of one specific charge / discharge stand for rapid charging selected by the control unit CD from the m specific charge / discharge stands for rapid charging connected to the m DC connection circuits.

[0045] Furthermore, other components, including the nm first feed lines and nm first DC relays, the n-1 second feed lines SL21 to SL24 and the n-1 second DC relays R21 to R24, and the closed loop forming second feed line SL25 and the closed loop forming second DC relay R25, included in the nm DC connection circuits other than the m DC connection circuits, each have an installed capacity required to supply a small amount of power that is less than the combined DC power to the nm DC connection circuits.

[0046] When one specific charge / discharge stand for quick charging is selected, the control unit CD controls the opening and closing of the n first DC relays and the n-1 second DC relays R21 to R24, as well as the second DC relay R25 for forming a closed loop, so that small power is not supplied to the DC connection circuits of charge / discharge stands other than the specific charge / discharge stand. Note that when no specific charge / discharge stand for quick charging is selected, the control unit CD controls the opening and closing of the n first DC relays and the n-1 second DC relays R21 to R24, as well as the second DC relay R25 for forming a closed loop, so that small power is supplied to the DC connection circuits of each charge / discharge stand.

[0047] Specific operations of the control unit CD will be described below with reference to Figs. 2 to 5, assuming a typical usage situation when this embodiment is installed in a company's private parking lot. Fig. 2 shows a normal usage situation by a business that uses electric vehicles EV for business purposes, i.e., a situation in which 10 kW normal charging is performed at all charging / discharging stations. That is, in Fig. 2, the control unit CD opens all of the first DC relays R11 to R15 and closes all of the second DC relays R21 to R25. This allows 10 kW normal charging (small capacity charging) at all five charging / discharging stations S1 to S5.

[0048] 3 shows a state when the specific charging / discharging station S1 for rapid charging is switched to 50 kW rapid charging (large-capacity charging), continuing from the state in FIG. 2. That is, in FIG. 3, the second DC relay R23 is in an open state, the second DC relays R21, R22, R24, and R25 are in a closed state, the first DC relay R11 is in a closed state, and the first DC relays R12 to R15 are in an open state. In this embodiment, rapid charging is performed with a total power supply capacity of 50 kW for the charging / discharging unit U, and therefore, normal charging is stopped (charging standby) at S2 to S5 other than the specific charging / discharging station S1 for rapid charging, thereby enabling 50 kW rapid charging (large-capacity charging) at one specific charging / discharging station S1.

[0049] In the state shown in Figure 3, when electric vehicle EV1 is connected to connector C of a specific charging / discharging station S1 for rapid charging and a user presses the start button on touch display DP1, electric vehicle EV1 and charge / discharge control board SB1 begin communication, and information from touch display DP1 and charge / discharge control board SB1 is sent to control unit CD. Next, control unit CD sends a charge stop command to charge / discharge control boards SB1-SB5 to stop charge / discharge power supply circuits PS1-PS5, and also sends open commands to first DC relays R11-R15 and second DC relays R21-R25 to open these relays. After that, control unit CD sends a close command to first DC relay R11 and second DC relays R21, R22, R24, and R25 to close these relays, and sends a charge start command, including the charge capacity, to charge / discharge control boards SB1-SB5. The charge / discharge control boards SB1 to SB5 send a charge start command, including the charge capacity, to the charge / discharge power supply circuits PS1 to PS5, and the charge / discharge power supply circuits PS1 to PS5 begin outputting the charge capacity as instructed. When charging is complete and charging is to be stopped, the control unit CD also sends a charge stop command to the charge / discharge power supply circuits PS1 to PS5 via the charge / discharge control boards SB1 to SB5, and an open command is given to the first DC relay R11 and the second DC relays R21, R22, R24, and R25. This completes rapid charging (large-capacity charging) at the specific charge / discharge stand S1, as shown in Figure 3.

[0050] Continuing from the state in Figure 3, the state in Figure 4 shows a situation where charging of the battery B1 of the electric vehicle EV1 connected to the connector C of the specific charging / discharging station S1 is completed (fully charged) and stopped by rapid charging at the specific charging / discharging station S1, and then the charging is switched to 50 kW rapid charging (large-capacity charging) at another specific rapid charging station S2. That is, in the state in Figure 4, the control unit CD opens the second DC relay R24, closes the second DC relays R21, R22, R23, and R25, closes the first DC relay R12, and opens the first DC relays R11 and R13 to R15. In this embodiment, rapid charging is performed with a total power supply capacity of 50 kW for the charging / discharging system 1, and normal charging is stopped (charging standby) at S1 and S3 to S5 other than the specific charging / discharging station S2 where rapid charging is performed, thereby enabling one specific charging / discharging station S2 to perform rapid charging (large-capacity charging) at 50 kW.

[0051] In the state shown in Fig. 4, the control unit CD sends a charge stop command to the charge / discharge control boards SB1 to SB5 to stop the charge / discharge power supply circuits PS1 to PS5, and also sends an open command to the first DC relays R11 to R15 and the second DC relays R21 to R25 to open these relays. The control unit CD then sends a close command to the first DC relay R12 and the second DC relays R21, R22, R23, and R25 to close these relays, and sends a charge start command including the charge capacity to the charge / discharge control boards SB1 to SB5. The charge / discharge control boards SB1 to SB5 send the charge start command including the charge capacity to the charge / discharge power supply circuits PS1 to PS5, and the charge / discharge power supply circuits PS1 to PS5 start outputting the charge capacity as instructed. When charging is completed and charging is to be stopped, a charge stop command is sent from the control unit CD to the charge / discharge power supply circuits PS1 to PS5 via the charge / discharge control boards SB1 to SB5, and an open command is given to the first DC relay R12 and the second DC relays R21, R22, R23, and R25. This completes rapid charging (large-capacity charging) at the specific charge / discharge stand S1 as shown in Figure 4.

[0052] Fig. 5 shows a state in which the batteries B1 and B2 of electric vehicles EV1 and EV2 connected to connectors C of specific charging / discharging stations S1 and S2 for rapid charging have completed charging (fully charged) and stopped charging, and the remaining other charging / discharging stations S3 to S5 have resumed normal charging. That is, in the state of Fig. 5, the control unit CD opens the second DC relays R21, R23, and R24, closes the second DC relays R22 and R25, opens the first DC relays R11 and R12, and closes the first DC relays R13 to R15. In a first mode, the other charging / discharging stations S3 to S5 have an installed capacity capable of normal charging (small-capacity charging) of up to 20 kW, and the specific charging / discharging stations S1 and S2 have stopped full charging, leaving a surplus of 20 kW in the power supply capacity of the charging / discharging system 1. As a result, as shown in Figure 5, of the other three charging / discharging stations, stations S3 and S5 are capable of 20kW normal charging (small capacity charging), and the remaining charging / discharging station S4 is capable of 10kW normal charging (small capacity charging).

[0053] The display operation of the touch displays DP1 to DP5 provided on the five charging / discharging stations S1 to S5 is optional. For example, when the first DC relay R11 of the specific charging / discharging station S1 for quick charging is closed, the first DC relays R12 to R15 of the other charging / discharging stations S2 to S5 may remain open, and the touch displays DP2 to DP5 of the other charging / discharging stations S2 to S5 may display the waiting time until they become available for use. This allows users to know that the other charging / discharging stations S2 to S5 are not malfunctioning and to wait. Furthermore, when at least one of the first DC relays of the other charging / discharging stations S2 to S5 is closed, the first DC relay R11 and the four second DC relays R21 to R24 of the specific charging / discharging station S1 for quick charging are preferably open, and the touch display DP1 of the specific charging / discharging station S1 for quick charging may display the waiting time until they become available for use. In this way, users of the specific rapid charging station S1 can know that the specific rapid charging station S1 is not malfunctioning and can wait. The control unit CD has the function of calculating the waiting time at each station S1 to S5 based on the usage status of each station S1 to S5, and sending a command to each station to display the waiting time on the touch display of each station.

[0054] According to the first aspect of the invention described above with reference to FIGS. 1 to 5, by configuring some of the DC connection circuits DC1 to DC5 with high-capacity components, the number of specific charging / discharging stations for rapid charging can be increased as desired, thereby increasing the number of parking spaces where rapid charging is possible, thereby improving user convenience. In this case, since there is no need to replace the terminal connection circuits TC1 to TC4 with high-capacity ones, the facility can be constructed at low cost. Furthermore, according to the first aspect of the invention, by having the control unit CD appropriately control the opening and closing of the first DC relays R11 to R15 and the second DC relays R21 to R25, it is possible to add power supply capacity to adjacent charging / discharging stations of the charging / discharging power supply circuit corresponding to a charging / discharging station where charging has finished, thereby improving the power utilization rate of the charging / discharging system 1.

[0055] [Charge / Discharge System of Second Aspect] Fig. 6 shows the basic configuration of a charging / discharging system 11 according to a second embodiment of the present invention (a configuration in which normal charging is performed at all charging / discharging stations S1 to S5). Fig. 7 shows an embodiment in which the central charging / discharging station S3 is a specific charging / discharging station for rapid charging. The difference between the charging / discharging system 11 according to the second embodiment shown in Figs. 6 and 7 and the charging / discharging system 1 according to the first embodiment shown in Figs. 1 to 5 is that the number of specific charging / discharging stations capable of rapid charging is limited to one, the central charging / discharging station S3, without using the inter-terminal connection circuit TC5 including the second power supply line SL25 and the second DC relay R25 arranged between the two DC terminals DT1 and DT5 used in the embodiment shown in Figs. 1 to 5.

[0056] To explain this embodiment conceptually, n (five in FIG. 7 ) or more odd number of electric vehicles EV1 to EV5 are used, which perform a charging operation of charging at least one of n battery storage devices B1 to B5 mounted on each of the n (five in FIG. 7 ) or more electric vehicles EV1 to EV5 using charging power received by a power receiving facility PR, and a discharging operation of supplying power from at least one of the n battery storage devices B1 to B5 to a load L electrically connected to the power receiving facility PR. The first power feed line SL13 and the first DC relay R13 included in one DC connection circuit (DC3) of the n DC connection circuits DC1 to DC5 each have an installation capacity required to supply combined DC power output from the n battery storage devices PS1 to PS5 in one charging to a battery storage device (B3) of an electric vehicle (EV3) connected to a connector C of a specific rapid charging / discharging stand (S3) connected to one DC connection circuit (DC3). Furthermore, other components, including the n-1 first power feed lines and n-1 first DC relays, as well as the n-1 second power feed lines SL21-SL24 and n-1 second DC relays R21-R24, included in the n-1 (four in FIG. 7) DC connection circuits other than the one DC connection circuit, each have a minimum installed capacity required to supply small power that is less than the combined DC power. When a specific charging / discharging stand for quick charging is selected, the control unit CD controls the opening and closing of the n first DC relays and the n-1 second DC relays R21-R24 so that small power is not supplied to the DC connection circuits of charging / discharging stands other than the specific charging / discharging stand.

[0057] In the example of Figure 7, a single DC connection circuit DC3 located in the center supplies composite DC power to a battery B3 of an electric vehicle EV3 connected to connector C of a specific charging / discharging station S3. In this way, although convenience for users is reduced, the number of large-capacity, expensive parts used can be reduced, making it possible to build facilities at lower cost.

[0058] The control unit CD controls the opening and closing of the second DC relays R21-R24 and the first DC relays R11-R15 included in the four terminal-to-terminal connection circuits TC1-TC4 so that all of the combined DC power output from the five charge / discharge power supply circuits PS1-PS5 can be supplied to the charge / discharge stand S3 connected to one DC connection circuit DC3. That is, in the state shown in Fig. 7, the control unit CD closes the second DC relays R21-R24, closes the first DC relay R13, and opens the first DC relays R11, R12, R14, and R15, thereby enabling the charge / discharge stand S3 to be used as a specific charge / discharge stand capable of rapid charging.

[0059] 7, it is also possible to designate a charging / discharging station connected to one of the DC connection circuits other than the central DC connection circuit DC3 as the specific charging / discharging station. For example, to designate charging / discharging station S1 as the specific charging / discharging station, all of the second DC relays R21 to R24 are closed, the first DC relay R11 is closed, and the first DC relays R12 to R15 are open. In this case, the first DC relay R11 and the second DC relays R21 to R24 should each have an installed capacity sufficient to supply the combined DC output of the five charging / discharging power supply circuits PS1 to PS5 during one charging to the battery B1 of the electric vehicle EV1 connected to the connector C of one specific fast-charging charging / discharging station S1. Each of the first DC relays R12 to R15 only needs to have the minimum facility capacity required to supply power to the battery (B2 to B5) of one electric vehicle (EV2 to EV5) connected to one charging / discharging station (S2 to S5).

[0060] As with the first aspect of the invention, the control unit CD can add the function of supplying power to adjacent charge / discharge stands of the charge / discharge power supply circuits PS1 to PS5 corresponding to the charge / discharge power stand where charging has completed by appropriately controlling the opening and closing of the first DC relays R11 to R15 and the second DC relays R21 to R24.

[0061] [Charge / discharge system according to the third aspect] FIG. 8 shows the basic configuration of a charging / discharging system 12 according to a third aspect of the present invention. The configuration in FIG. 8 is basically the same as that in the second embodiment where n=3. Therefore, the DC connection circuit DC2 located in the center is used as a specific charging / discharging station capable of rapid charging. However, in this aspect, each charging / discharging station is provided with two connectors C and C', and the control unit CD is configured to charge the storage batteries (B1 and B2, B3 and B4, B5 and B6) of two electric vehicles at one charging / discharging station.

[0062] [Combined charging and discharging system] FIG. 9 is a diagram showing a specific example of a fourth embodiment using a charging / discharging system 12 according to the third aspect of the present invention. In the state shown in FIG. 9, the number n of charging / discharging stations in the charging / discharging system 11 according to the second embodiment is set to a minimum of three, and a plurality of such stations are installed to form a combined charging / discharging system 13. The combined charging / discharging system 13 shown in FIG. 9 includes first and second charging / discharging units U1 and U2 connected in parallel to a power receiving facility PR. The components constituting the second charging / discharging unit U2 are numbered consecutively from the reference numerals assigned to the components constituting the first charging / discharging unit U1. The charging / discharging control board (SB) and control unit (CD) shown in the other embodiments described above are omitted from FIG. 9. Because the two charging / discharging units U1 and U2 have the same configuration, only the first charging / discharging unit U1 will be described. Similar to the charging / discharging system 12 of Figure 8, one charging / discharging unit U1 uses three parallel-connected charging / discharging power supply circuits PS1 to PS3 to perform a charging operation of charging at least one of six battery cells B1 to B6 mounted on each of electric vehicles EV1 to EV3' connected to three charging / discharging stations S1 to S3 using charging power received by the power receiving equipment PR, and a discharging operation of supplying power from at least one of the six battery cells (B1 to B6) to a load L electrically connected to the power receiving equipment PR. The first power feed line SL12 and first DC relays R12A and R12B included in the single DC connection circuit DC2 located at the center of the three DC connection circuits DC1 to DC3 each have an installed capacity required to supply composite DC power, which is a combination of DC power output from the three charge / discharge power supply circuits PS1 to PS3 in one charge, to the battery B3 (B4) of the electric vehicle EV2 (EV2') connected to the connector C (C') of the specific charge / discharge stand S2 for rapid charging, which is connected to the single DC connection circuit DC2. The second power feed lines SL21 and SL22 and second DC relays R21 and R22 included in the two inter-terminal connection circuits TC1 and TC2 each have an installed capacity required to supply DC power output from the charge / discharge power supply circuits PS1 and PS, respectively, to the single DC connection circuit DC2.

[0063] Furthermore, the first power feed lines SL11 and SL13 and the first DC relays R11A and R11B and R13A and R13B included in the two DC connection circuits DC1 and DC3 other than the one DC connection circuit DC2 respectively have the minimum installed capacity required to supply the DC power output from the corresponding charge / discharge power supply circuits PS1 and PS3 to the capacitors B1 and B2 and B5 and B6 of the electric vehicles connected to the charge / discharge stations S1 and S3.

[0064] A control unit CD (not shown) controls the opening and closing of the second DC relays R21 and R22 and the first DC relays R11A-R13B included in the two inter-terminal connection circuits TC1 and TC2 so that all of the combined DC power output from the three charge / discharge power supply circuits PS1-PS3 can be supplied to the specific charge / discharge station S2 for rapid charging connected to one DC connection circuit DC2. This configuration enables the specific charge / discharge station S2 located in the center to perform large-capacity charging while reducing the amount of large-capacity, expensive components used. The configuration and operation of the second charge / discharge unit U2 are the same as those of the first charge / discharge unit U1, so a detailed description is omitted. This combined charge / discharge system 13 can be easily expanded by adding additional charge / discharge units.

[0065] Fig. 10 is a configuration diagram of the combined charging / discharging system 13 shown in Fig. 9 when the charging / discharging units U1 and U2 are attached to utility poles. By arranging the charging / discharging units U1 and U2 side by side on utility poles for power lines that receive power from power-receiving equipment in this way, it is possible to reduce the installation space and installation costs for the combined charging / discharging system 13. [Industrial Applicability]

[0066] According to the present invention, it is possible to provide an inexpensive charging / discharging system that allows the selection of either rapid charging (large-capacity charging) or normal charging (small-capacity charging), which is slower than rapid charging, for the storage batteries of multiple electric vehicles. [Explanation of symbols]

[0067] 1,11,12 Charging and discharging system 13 Combined charging and discharging system U, U1, U2 charge / discharge unit PR power receiving equipment EV1~EV5 Electric Vehicles B1~B5 Capacitor PS1~PS5 Charge / discharge power supply circuit S1~S5 Charging / Discharging Stand SL11~SL15 1st feeder line SL21~SL25 Second feeder line R11~R15 First DC relay R21~R25 Second DC relay DT1~DT5 DC terminal DC1~DC5 DC connection circuit TC1~TC5 terminal connection circuit LC closed loop circuit

Claims

1. a power receiving facility that receives and demands power from a commercial power source; n charge / discharge power supply circuits connected in parallel that perform a charging operation of charging at least one of n (n is a positive integer of 3 or more) battery units mounted on each of the n electric vehicles using charging power received by the power receiving equipment, and a discharging operation of supplying power from at least one of the n battery units to a load electrically connected to the power receiving equipment; n charging / discharging stations each having a connector for connecting the n charging / discharging power supply circuits to the n electric storage devices of the n electric vehicles; n DC connection circuits, each including a first power supply line and a first DC relay, arranged between the n charging / discharging stands and the n charging / discharging power supply circuits; n-1 inter-terminal connection circuits including second feed lines and second DC relays arranged between two adjacent DC terminals to interconnect the n DC terminals of the n charging / discharging power supply circuits and to form a closed loop circuit; and one closed loop-forming inter-terminal connection circuit including a second closed loop-forming feed line and a second closed loop-forming DC relay arranged between two DC terminals located at both ends; a control unit that controls switching of charge and discharge operations of the n plurality of charge and discharge power supply circuits and switching of opening and closing operations of the plurality of first DC relays and the plurality of second DC relays, the first power feed line and the first DC relay included in m (m is an integer equal to or greater than 1 and less than n) DC connection circuits out of the n DC connection circuits each have an installed capacity necessary to supply combined DC power output from the n charge / discharge power supply circuits in one charging operation to the battery of the electric vehicle connected to the connector of one specific charge / discharge stand for rapid charging selected by the control unit from m specific charge / discharge stands for rapid charging connected to the m DC connection circuits, other components, including the nm number of first feed lines and the nm number of first DC relays, the n-1 number of second feed lines and the n-1 number of second DC relays, and the closed-loop-forming second feed line and the closed-loop-forming second DC relay, included in the nm number of DC connecting circuits other than the m number of DC connecting circuits, each have an installed capacity required to supply a small amount of power that is less than the combined DC power to the nm number of DC connecting circuits, The charging / discharging system is characterized in that, when the control unit selects one specific charging / discharging stand for rapid charging, it controls the opening and closing of n first DC relays, n-1 second DC relays, and the second DC relay for forming a closed loop so that the small power is not supplied to the DC connection circuits of the charging / discharging stands other than the specific charging / discharging stand.

2. 2. The charging / discharging system according to claim 1, wherein when said n is 5 and said m is 2, said small power is 1 / 5 to 2 / 5 of said combined DC power.

3. a power receiving facility that receives and demands power from a commercial power source; n charge / discharge power supply circuits connected in parallel that perform a charging operation of charging at least one of n (n is a positive integer of 3 or more) battery units mounted on each of the n electric vehicles using charging power received by the power receiving equipment, and a discharging operation of supplying power from at least one of the n battery units to a load electrically connected to the power receiving equipment; n charging / discharging stations each having a connector for connecting the n charging / discharging power supply circuits to the n electric storage devices of the n electric vehicles; n DC connection circuits, each including a first power supply line and a first DC relay, arranged between the n charging / discharging stands and the n charging / discharging power supply circuits; n-1 inter-terminal connection circuits including second feed lines and second DC relays arranged between two adjacent DC terminals to interconnect the n DC terminals of the n charging / discharging power supply circuits and to form a closed loop circuit; and one closed loop-forming inter-terminal connection circuit including a second closed loop-forming feed line and a second closed loop-forming DC relay arranged between two DC terminals located at both ends; a control unit that controls switching of the charge and discharge operations of the plurality of charge and discharge power supply circuits and switching of the opening and closing operations of the plurality of first DC relays and the plurality of second DC relays, the two DC connection circuits and the first DC relay connected to one of the DC terminals to which the closed-loop forming terminal-to-terminal connection circuit is connected and another DC terminal adjacent to the one DC terminal each have an installed capacity required to supply a composite DC power obtained by combining DC powers output from the n charge / discharge power supply circuits to the battery of the electric vehicle connected to the connector of one specific charge / discharge stand selected by the control unit from the two specific charge / discharge stands for quick charging connected to the two DC connection circuits, other components including the n-2 first power feed lines and the n-2 first DC relays, the n-1 second power feed lines and the n-1 second DC relays, and the closed loop-forming second power feed line and the closed loop-forming second DC relay included in the n-2 DC connection circuits other than the two DC connection circuits each have a minimum installed capacity required to supply a small power that is less than the combined DC power, The charging / discharging system is characterized in that, when the control unit selects the one specific charging / discharging stand for rapid charging, it controls the opening and closing of the n first DC relays, the n-1 second DC relays, and the second DC relay for forming a closed loop so that the small power is not supplied to the DC connection circuits of the charging / discharging stands other than the specific charging / discharging stand.

4. 4. The charging / discharging system according to claim 3, wherein the control unit controls opening and closing of the second DC relay included in the n-1 terminal-to-terminal connection circuits and the closed-loop forming second DC relay included in the closed-loop forming terminal-to-terminal connection circuit so as to supply the combined DC power output from the two charging / discharging power supply circuits to the remaining charging / discharging stand without supplying the combined DC power output from the n charging / discharging power supply circuits to either of the two specific charging / discharging stands.

5. a power receiving facility that receives and demands power from a commercial power source; n charge / discharge power supply circuits connected in parallel that perform a charging operation of charging at least one of n (n is a positive odd number equal to or greater than 3) battery units mounted on each of the n electric vehicles using charging power received by the power receiving equipment, and a discharging operation of supplying power from at least one of the n battery units to a load electrically connected to the power receiving equipment; n charging / discharging stations each having a connector for connecting the n charging / discharging power supply circuits to the n electric storage devices of the n electric vehicles; n DC connection circuits, each including a first power supply line and a first DC relay, arranged between the n charging / discharging stands and the n charging / discharging power supply circuits; n-1 inter-terminal connection circuits including a second power supply line and a second DC relay arranged between two of the n DC terminals to interconnect the n DC terminals of the n charging / discharging power supply circuits; a control unit that controls switching of the charge and discharge operations of the plurality of charge and discharge power supply circuits and switching of the opening and closing operations of the plurality of first DC relays and the plurality of second DC relays, the first power feed line and the first DC relay included in one DC connection circuit of the n DC connection circuits each have an installation capacity required to supply a combined DC power obtained by combining the DC powers output from the n charge / discharge power supply circuits in one charging operation to the battery of the electric vehicle connected to the connector of a specific charge / discharge stand for rapid charging connected to the one DC connection circuit, other components, including the n-1 first power feed lines and the n-1 first DC relays, as well as the n-1 second power feed lines and the n-1 second DC relays, included in the n-1 DC connection circuits other than the one DC connection circuit, each have a minimum installed capacity required to supply a small amount of power that is less than the combined DC power, The charging / discharging system is characterized in that, when a specific charging / discharging stand for the rapid charging is selected, the control unit controls the opening and closing of n first DC relays and n-1 second DC relays so that the small power is not supplied to the DC connection circuits of the charging / discharging stands other than the specific charging / discharging stand.

6. wherein n is 5; a first power feed line and a first DC relay included in one DC connection circuit located at the center of the n DC connection circuits have an installed capacity required to supply a combined DC power obtained by combining DC power output from five charge / discharge power supply circuits in one charging to a battery of an electric vehicle connected to a connector of a specific charge / discharge stand for rapid charging connected to one DC connection circuit, 6. The charging / discharging system according to claim 5, wherein the small power is equal to or less than 2 / 5 of the combined DC power.

7. 6. The charging / discharging system according to claim 5, wherein said n is 3, and said small power is equal to or less than one-third of said combined DC power.

8. The charging / discharging system according to any one of claims 1 to 7, wherein each of the n charging / discharging stands includes a plurality of the connectors, and the n charging / discharging stands and the control unit are configured to charge the storage batteries of a plurality of the electric vehicles at one charging / discharging stand.

9. A combined charging / discharging system, in which charging / discharging units constituted by a plurality of charging / discharging systems according to any one of claims 5 to 7, excluding the plurality of charging / discharging stands, are provided in parallel to a common charging facility.

10. The combined charging / discharging system according to claim 9 , wherein a plurality of the charging / discharging units are mounted on one or more utility poles.

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