Charging and discharging device, charging and discharging control method and storage medium

Abstract

Provided are a charging and discharging device, a charging and discharging control method, and a computer program that can exhibit high responsiveness even in accordance with a prescribed timing corresponding to a charging and discharging method. The charging and discharging device has a connector connected to an on-board power line, the on-board power line is connected to a storage battery installed in a vehicle, and the charging and discharging device controls the charging and discharging of the storage battery, wherein the charging and discharging device includes: a communication unit that is connected to an on-board control device for communication, and the on-board control device switches the connection and disconnection of a vehicle-side relay installed on the on-board power line; a communication control unit that transmits and receives messages to and from the on-board control device via the communication unit based on a prescribed timing; and a connection standby state maintaining unit that maintains the vehicle-side relay in a connection standby state in which the vehicle-side relay is kept connected during a period in which the charging and discharging of the storage battery is not performed after the vehicle-side relay is switched to be connected based on the prescribed timing.

Description

Technical Field

[0001] The present invention relates to a charging and discharging device connected to a storage battery provided in a vehicle, a charging and discharging control method, and a storage medium. Background Art

[0002] The battery capacity of the battery of an electric vehicle is, for example, a relatively large capacity of 5 to 100 kWh. The following technology is proposed: in addition to using the electricity stored in the above-mentioned vehicle to drive the electric vehicle, it is also used to realize V2X, including, for example, V2H (Vehicle to Home) that can be supplied to homes, V2B (Vehicle to Building) that can be supplied to buildings not limited to homes, and V2G (Vehicle to Grid) that can be supplied to the power grid. It is expected that even if there is a power outage due to a disaster, the electricity stored in the movable electric vehicle can be supplied to maintain life and maintain factory work. In the case of realizing V2X, it is expected to be able to accept control from the EMS (Energy Management System) and perform charging and discharging in a planned manner.

[0003] Regarding a charging and discharging device for realizing V2H, Patent Document 1 proposes a device that controls charging and discharging by grasping the connection between the vehicle and the charging and discharging device on the charging and discharging device side without turning on a relay on the charging and discharging device side installed on a power line connected to a battery of the vehicle.

[0004] Patent Document 2 discloses a technology for stopping charging when a voltage fluctuation phenomenon occurs in which the voltage from a commercial power source repeatedly drops and recovers in order to protect an on-vehicle charging and discharging circuit including an ACDC converter for adjusting power supplied to a battery installed in an electric vehicle.

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5642226

[0008] Patent Document 2: Japanese Patent Application Publication No. 2013-090459 Summary of the invention

[0009] Summary of the Invention

[0010] Problems to be solved by the invention

[0011] As also disclosed in Patent Document 1, the connection detection of the power line between the vehicle and the charging and discharging device, the establishment of the communication connection between the vehicle and the charging and discharging device, and the start and stop of charging and discharging are safely performed in accordance with a prescribed sequence corresponding to any of several charging and discharging methods. The control of charging and discharging needs to follow the steps corresponding to the prescribed sequence, and it is difficult to respond to the control instructions from the EMS that require a quick response. The switching of the operation and stop of charging and discharging requires the switching of the DC relay on the vehicle side, the DC relay on the charging and discharging device side, and the disconnection relay. In the case where the switching of the operating mode is repeated to match the detailed control, the connection and disconnection of the above-mentioned relay are frequently repeated, resulting in the deterioration of the relay, which may be damaged prematurely.

[0012] An object of the present invention is to provide a charge and discharge device, a charge and discharge control method, and a storage medium storing a computer program that can suppress degradation and exhibit high responsiveness despite following a predetermined timing corresponding to a charge and discharge pattern.

[0013] Solutions to Solve Problems

[0014] A charging and discharging device of one embodiment of the present disclosure has a connector connected to a vehicle-mounted power line, the vehicle-mounted power line is connected to a battery installed in the vehicle, and the charging and discharging device controls the charging and discharging of the battery, wherein the charging and discharging device includes: a communication unit, which is communicatively connected to a vehicle-mounted control device, and the vehicle-mounted control device switches the connection and disconnection of a relay on the vehicle side installed on the vehicle-mounted power line; a communication control unit, which sends and receives messages with the vehicle-mounted control device via the communication unit based on a specified timing; and a connection standby state maintaining unit, which maintains the relay on the vehicle side in a connection standby state in which the relay is kept connected during a period when the charging and discharging of the battery is not performed after switching the relay on the vehicle side to connected based on the specified timing.

[0015] A charge and discharge control method according to an embodiment of the present disclosure enables a charge and discharge device to control the charge and discharge of a battery installed in a vehicle, the charge and discharge device having a connector connected to a vehicle-mounted power line, the vehicle-mounted power line being connected to the battery, wherein the charge and discharge device is communicatively connected to a vehicle-mounted control device, the vehicle-mounted control device switches on and off a relay on the vehicle side installed on the vehicle-mounted power line, the charge and discharge device and the vehicle-mounted control device send and receive messages based on a specified timing, and after the charge and discharge device switches the relay on the vehicle side to on based on the specified timing, the charge and discharge device maintains the relay on the vehicle side in a connected standby state during a period in which the charge and discharge of the battery is not performed.

[0016] A computer program of one embodiment of the present disclosure enables a computer to execute processing, wherein the computer is mounted on a charging and discharging device, the charging and discharging device has a connector connected to a vehicle-mounted power line, the vehicle-mounted power line is connected to a battery installed in the vehicle, the charging and discharging device has a communication unit that communicates with a vehicle-mounted control unit, the vehicle-mounted control unit switches on and off a relay on the vehicle side installed on the vehicle-mounted power line, wherein the processing includes: sending and receiving messages between the charging and discharging device and the vehicle-mounted control unit through the communication unit based on a specified timing; and after switching the relay on the vehicle side to on based on the specified timing, maintaining the relay on the vehicle side in a connected standby state during a period when charging and discharging of the battery is not performed.

[0017] In one embodiment of the present disclosure, the vehicle-side relay is maintained not to be switched off by the control in the charge and discharge control device on the vehicle side. If the relay of the vehicle-mounted power line is disconnected, the steps corresponding to the prescribed timing must be re-implemented until the charge and discharge are started, which takes time. However, by reducing the time and maintaining the vehicle-side relay on, a quick response to the control of the charge and discharge can be achieved.

[0018] A charging and discharging device according to one embodiment of the present disclosure includes a charging and discharging circuit, which includes a relay for switching on and off the transfer of power between the battery and a commercial power supply or a load. In the connection standby state, the relay on the vehicle side is turned on and the relay of the charging and discharging circuit is turned off.

[0019] In a charging and discharging device of one embodiment of the present disclosure, the relay of the charging and discharging circuit includes: a decoupling relay for switching on and off the power transfer between the charging and discharging circuit and the commercial power supply; and a device-side relay installed between the charging and discharging circuit and the connector, wherein in the connection standby state, the decoupling relay is disconnected and the device-side relay is connected.

[0020] In one embodiment of the present disclosure, in a connection standby state in which the relay on the vehicle side is kept turned on, at least one of the multiple relays provided inside the charging and discharging device is turned off. The device-side relay installed between the connector and the charging and discharging circuit is kept turned on in the same way as the vehicle-side relay. By suppressing the number of switching times of the relay being turned on or off as much as possible, power consumption can be suppressed and degradation of the relay can be suppressed. It should be noted that the decoupling relay provided inside the charging and discharging device can also be kept turned on, in which case a faster response can be achieved.

[0021] In the charging and discharging device of one embodiment of the present disclosure, the connection standby state maintaining unit turns off the relay on the charging and discharging circuit side, and transmits a message indicating the charging and discharging current value of the approximate lower limit value determined to be during charging or discharging to the vehicle-mounted control device through the communication control unit.

[0022] In one embodiment of the present disclosure, in the vehicle-mounted control device, it is configured that the relay on the vehicle side can be maintained on during charging and discharging at a minimum current value.

[0023] In a charging and discharging device of one embodiment of the present disclosure, the connection standby state maintaining unit determines whether the charging rate of the battery is above a specified first charging rate for judging as fully charged. When the connection standby state maintaining unit determines that the charging rate of the battery is above the first charging rate, the unit sends a message indicating a discharge current value judged as being discharged to the vehicle-mounted control unit.

[0024] In one embodiment of the present disclosure, when the power storage device of the vehicle is in a fully charged state, the on-vehicle control device assumes that minimum discharge is being performed and can maintain the relay on the vehicle side in an on-state.

[0025] In a charging and discharging device of one embodiment of the present disclosure, the connection standby state maintaining unit determines whether the charging rate of the battery is below a specified second charging rate which is determined to be a lower limit. When the connection standby state maintaining unit determines that the charging rate of the battery is above the second charging rate, the connection standby state maintaining unit turns on the relay of the charging and discharging circuit and charges the battery with power from the commercial power supply until the charging rate of the battery reaches a specified third charging rate. The connection standby state maintaining unit sends a message indicating the charging current value to the vehicle-mounted control unit.

[0026] In one embodiment of the present disclosure, when the charge rate of the power storage device of the vehicle is in an empty state (lower limit), the relay on the vehicle side can be maintained on as if minimum charging is being performed.

[0027] In a charging and discharging device of one embodiment of the present disclosure, the connection standby state maintaining unit disconnects the relay on the vehicle side to cut off the communication connection based on the communication unit when at least any one of the following conditions is met: whether a specified time has passed since the start of maintaining the connection standby state, whether the charging rate of the battery is below a specified second charging rate judged as a lower limit, or whether the charging rate of the battery has decreased by more than a specified proportion since the start of maintaining the connection standby state.

[0028] In one embodiment of the present disclosure, the vehicle-side relay is kept in a connected standby state for a long time, and the remaining power of the battery may continue to be consumed. In this case, the relay is turned off and the communication connection is also cut off. Thus, the connection is not maintained excessively and the charging and discharging device operates appropriately.

[0029] A charging and discharging device according to one embodiment of the present disclosure includes a charging and discharging circuit, which includes a relay for switching on and off the transfer of power between the battery and a commercial power supply or a load, and the connection standby state maintaining unit turns on both the relay on the vehicle side and the relay of the charging and discharging circuit, and charges or discharges with power set to a lower limit.

[0030] It is also possible to maintain the connection of the relay provided inside the charging and discharging device, in which case a faster response can be achieved. In this case, the connection standby state maintaining unit performs charging and discharging with a minimum output. It should be noted that, here, the "lower limit" and "minimum limit" are not limited to zero, and can be, for example, an output of 50 to 100W.

[0031] A charging and discharging device according to one embodiment of the present disclosure comprises: a host control communication unit that exchanges data with a host control unit that instructs charging and discharging of a battery in the vehicle; and a judgment unit that judges whether to change to a protection state for protecting the relay based on information related to the battery obtained from the on-board control unit via the communication unit and instructions from the host control unit received via the host control communication unit.

[0032] A charging and discharging method according to an embodiment of the present disclosure enables a charging and discharging device to control charging and discharging of a battery installed in a vehicle, the charging and discharging device having a connector connected to a vehicle-mounted power line, the vehicle-mounted power line being connected to the battery, wherein the charging and discharging device is communicatively connected to a vehicle-mounted control device, the vehicle-mounted control device switches on and off a relay installed on the vehicle side of the vehicle-mounted power line, the charging and discharging device exchanges data with a host control device that instructs charging and discharging of the battery in the vehicle, and the charging and discharging device determines whether to transition to a protection state for protecting the relay based on information related to the battery obtained from the vehicle-mounted control device through communication and instructions received from the host control device.

[0033] A computer program of one embodiment of the present disclosure enables a computer to execute processing, wherein the computer is mounted on a charging and discharging device, the charging and discharging device has a connector connected to a vehicle-mounted power line, the vehicle-mounted power line is connected to a battery installed in a vehicle, and the charging and discharging device has: a first communication unit that is communicatively connected to a vehicle-mounted control device, the vehicle-mounted control device switches the connection and disconnection of a relay installed on the vehicle side of the vehicle-mounted power line; and a second communication unit that exchanges data with a host control device, wherein the processing includes: obtaining information related to the battery from the vehicle-mounted control device via the first communication unit; obtaining an indication of charging and discharging in the battery from the host control device via the second communication unit; and judging whether to change to a protection state for protecting the relay based on the information related to the battery and the indication from the host control device.

[0034] In one embodiment of the present disclosure, when it is predicted that the vehicle's relays are repeatedly turned on and off due to a discrepancy between information related to the vehicle's battery obtained from the vehicle-mounted control device through communication and instructions from the upper control device (EMS or a controller provided inside the charging and discharging device), the vehicle is switched to a protection state. In the protection state, the vehicle's relays are controlled to be not turned on and off as much as possible. In the protection state, the relays provided in the charging and discharging device are also controlled to be not turned on and off as much as possible.

[0035] In the charge and discharge device according to one embodiment of the present disclosure, in the protection state, no response is given to a charge instruction or a discharge instruction from the host control device, or a negative response is returned to the instruction.

[0036] In one embodiment of the present disclosure, during the protection state, the vehicle becomes unresponsive to instructions from the EMS. Alternatively, in the case of not following instructions from the EMS as a protection state, an unresponsive, negative response (Negative Acknowledge), etc. are returned to the EMS. A negative response indicates a state in which the instructions are received but not followed. There is the possibility that a higher-level control device such as the EMS can infer that the control instruction being sent is inappropriate for the connected vehicle based on the fact that the charging and discharging device becomes unresponsive or returns a negative response.

[0037] The charge and discharge device according to one embodiment of the present disclosure transmits a transition notification to the protection state through the second communication unit.

[0038] In the charging and discharging device of the present disclosure, when the state changes to the protection state, a transition notification to the protection state is sent to the EMS. There is a possibility that the EMS receives the transition notification to the protection state and can infer that the control instruction being sent is inappropriate for the connected vehicle.

[0039] In the charge and discharge device according to one embodiment of the present disclosure, the determination unit determines that the state should be shifted to the protection state when the determination unit repeatedly receives the same instruction from the host control device within a predetermined period.

[0040] In the charging and discharging device of the present invention, when the same instruction is repeatedly received from the EMS or the internal controller, it is predicted that the instruction is inappropriate and no processing corresponding to the instruction is performed on the vehicle side. Since the processing is not performed, it is also expected that the same instruction will be repeated in the future, so it is judged to be transitioning to the protection state.

[0041] In the charge and discharge device according to one embodiment of the present disclosure, the determination unit determines that the state is shifted to the protection state when the upper control device switches the charge instruction and the discharge instruction a plurality of times or more within a predetermined period.

[0042] In the charging and discharging device disclosed in the present invention, even if different instructions are issued from the EMS or the internal controller, if they are repeated more than a plurality of times within a specified period, it is predicted that the instructions are inappropriate for the vehicle and the instructions will be further repeated, thereby repeatedly switching the relay on and off, and therefore the judgment unit judges that the state is transitioning to the protection state.

[0043] In the charge and discharge device of one embodiment of the present disclosure, the determination unit determines that the state is shifted to the protection state when the relay on the vehicle side is switched off by the on-vehicle control device and the same instruction is repeatedly received.

[0044] In the charging and discharging device of the present invention, when charging or discharging is instructed although charging and discharging are stopped by control on the vehicle side, it is predicted that the instruction from the EMS or the internal controller is inappropriate for the vehicle and the instruction will be further repeated, thereby repeatedly switching the relay on and off, and the judgment unit judges that it is transitioning to the protection state.

[0045] In a charging and discharging device of one embodiment of the present disclosure, the judgment unit judges to transition to a protection state when the judgment unit receives a charging instruction from the upper control device in a state where the charging rate of the battery is above a specified first ratio for judgment as full charge, or when the judgment unit receives a discharging instruction from the upper control device in a state where the charging rate of the battery is below a specified second ratio for judgment as a lower limit.

[0046] In the charging and discharging device of the present invention, when charging or discharging is instructed although charging and discharging are stopped by control on the vehicle side, it is predicted that the instruction from the EMS or the internal controller is inappropriate for the vehicle and the instruction will be further repeated, thereby repeatedly switching the relay on and off, and the judgment unit judges that it is transitioning to the protection state.

[0047] In the charge and discharge device according to one embodiment of the present disclosure, the determination unit acquires information on the vehicle type of the vehicle through the first communication unit, and determines whether to transition to the protection state based on transition conditions stored for each vehicle type.

[0048] In the charging and discharging device of the present disclosure, whether to transition to the protection state is determined according to the transition condition corresponding to the vehicle type, so that the charging control content on the vehicle side and the instructions from various EMS can be appropriately coordinated.

[0049] In the charge and discharge device according to one embodiment of the present disclosure, the determination unit determines that the state has returned from the protection state after a predetermined waiting time has elapsed since the state shifted to the protection state.

[0050] In the charge and discharge device of the present disclosure, after transitioning to the protection state, the device may return to the protection state after a predetermined waiting time has elapsed.

[0051] In the charging and discharging device of one embodiment of the present disclosure, the determination unit determines to recover from the protection state when the charging rate of the storage battery obtained by the first communication unit is less than the prescribed first ratio or when the charging rate of the storage battery exceeds the prescribed second ratio.

[0052] The charging and discharging device of the present disclosure can prevent the relay from being repeatedly switched on and off by returning from the protection state after confirming that the charging rate of the vehicle battery has returned to a chargeable state or a dischargeable state.

[0053] The charge and discharge device of the present disclosure may be restored when a reset instruction is given after the transition to the protection state. The reset instruction is an instruction given by operation in an interface operable by a user or an instruction from a higher-level control device maintaining a communication connection.

[0054] Effects of the Invention

[0055] According to the present disclosure, the connection state of the vehicle-mounted power line is maintained without the need to reset the sequence, and thus high responsiveness can be exhibited with respect to the instruction of charging and discharging. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1This is a schematic diagram of the charge and discharge device and EMS according to the first embodiment.

[0057] Figure 2 This is a block diagram showing a connection structure between the charging and discharging device and the vehicle according to the first embodiment.

[0058] Figure 3 This is a diagram showing an overview of charging and discharging controlled by the EMS.

[0059] Figure 4 This is a flowchart showing an example of a processing procedure performed by the control unit of the charging and discharging device.

[0060] Figure 5 This is a flowchart showing an example of a processing procedure performed by the control unit of the charge and discharge device.

[0061] Figure 6 This is a flowchart showing an example of a control procedure for maintaining the “connection standby state”.

[0062] Figure 7 This is a flowchart showing an example of a control procedure for transitioning the state between the "connection standby state" and the "disconnection standby state".

[0063] Figure 8 This is a flowchart showing an example of a transition procedure of the charging and discharging device to the protection state.

[0064] Fig. 9 This is a flowchart showing an example of a transition procedure of the charging and discharging device to the protection state.

[0065] Fig.10 This is a flowchart showing an example of a process procedure for determining whether to transition to the protection state.

[0066] Fig.11 This is a flowchart showing another example of the determination process procedure of whether to shift to the protection state.

[0067] Fig.12 This is a flowchart showing an example of a processing procedure for restoring from a protected state.

[0068] Fig.13 This is a flowchart showing an example of a transition procedure of the charge and discharge device to the protection state in the third embodiment.

[0069] Fig.14 This is a flowchart showing an example of a transition procedure of the charge and discharge device to the protection state in the third embodiment. DETAILED DESCRIPTION

[0070] The present disclosure will be described in detail with reference to the accompanying drawings showing embodiments of the present disclosure.

[0071] (Implementation Method 1)

[0072] Figure 1 It is a simplified diagram of the charging and discharging device 1 and EMS200 of embodiment 1. The load 21, the power generation device 23 and the charging and discharging device 1 arranged in the home are connected by means of the distribution board 28 and the power line PL. EMS200 is connected to the charging and discharging device 1 through the communication line CL. EMS200 is connected to the group of the power generation device 23, the load 21 and the distribution board 28 through a signal line or a communication line (not shown in the figure). The communication between EMS200 and the charging and discharging device 1 is not limited to the communication line CL, but can also be wireless communication, and can also be achieved through power line communication in the power line PL. EMS200 controls the transfer of power between the load 21 and the power system E, the power generation device 23 and the vehicle V. EMS200 can be replaced by a controller built into the charging and discharging device 1.

[0073] In another example, EMS200 controls the transfer of electric power between the power storage device 22 and the power generation device 23 installed in the parking lot as a public facility, and the vehicle V through the charging and discharging device 1, and the power system E. In this example, the power system E is connected to the power storage device 22, the power generation device 23, and a plurality of charging and discharging devices 1 via the distribution board 28 and the power line PL. In this example, EMS200 is connected to a plurality of charging and discharging devices 1 via the communication line CL. EMS200 is connected to the power storage device 22, the power generation device 23, and the distribution board 28 via a signal line or a communication line (not shown). The power system E, the power storage device 22, the power generation device 23, the charging and discharging device 1, and the load 21 can be connected in multiples to form a large-scale grid system.

[0074] Figure 2 1 is a block diagram showing the connection structure of the charging and discharging device 1 and the vehicle V of the first embodiment. The vehicle V is an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid vehicle (PHEV), or a fuel cell vehicle (FCV). The vehicle V is provided with a large-capacity power storage device 30 that can be used for its driving. The vehicle V is provided with a connector 35 connected to a power line VPL connected to the power storage device 30 and a vehicle-mounted charging and discharging control device 32 that controls the charging and discharging in the power storage device 30. A DC relay 33 included in the charging and discharging circuit on the vehicle V side is installed on the power line VPL, and the vehicle-mounted charging and discharging control device 32 controls the connection and disconnection of the DC relay 33. The connector 35 includes a communication terminal for communication connection with the vehicle-mounted charging and discharging control device 32.

[0075] The charging and discharging device 1 includes a charging and discharging circuit 10, a control unit 11, a communication unit 12, a power supply unit 13, an operation unit 14, and an output unit 15. The charging and discharging circuit 10 includes various circuit elements such as a bidirectional inverter and various relays. The charging and discharging circuit 10 includes a DC relay 10a connected to a connector 15 connected to the vehicle V, and a parallel-off relay 10b installed between the power line PL on the EMS 200 side and the power supply unit 13. The charging and discharging circuit 10 is connected to the connector 15 through the power line PL via the DC relay 10a.

[0076] The control unit 11 controls the circuit elements included in the charge and discharge circuit 10 to control the switching of charge and discharge, current and voltage of the power storage device 30 of the vehicle V. The control unit 11 includes a CPU (Central Processing Unit) and a memory, and the CPU executes a control process based on a computer program 1P stored in the memory to control the charge and discharge circuit 10. The computer program 1P can be a program in which the CPU reads a computer program 9P stored in a computer-readable storage medium 9 and stores it in the memory.

[0077] The communication unit 12 includes a vehicle communication unit 12a and an EMS communication unit 12b. The vehicle communication unit 12a is communicatively connected to the vehicle-mounted charge and discharge control device 32 via the connector 15 and the connector 35. The protocol of the communication connection of the vehicle communication unit 12a can comply with the charge and discharge method corresponding to the vehicle V, the connectors 15 and 35, or can correspond to a plurality of protocols and selectively execute any one of them so as to be applicable to different charge and discharge methods. In embodiment 1, the vehicle communication unit 12a communicates with the vehicle-mounted charge and discharge control device 32 via CAN (Controller Area Network). Communication can also be achieved through PLC.

[0078] The EMS communication unit 12b communicates with the EMS 200 via the communication line CL. The EMS communication unit 12b may be, for example, a communication module corresponding to the communication line CL in accordance with Ethernet (registered trademark) or a communication module corresponding to the communication line CL corresponding to ECHONET / ECHONETLite (registered trademark). The EMS communication unit 12b may also communicate via a PLC.

[0079] The power supply unit 13 includes a UPS (Uninterruptible Power Systems) circuit and a starting battery to supply power to the control unit 11. When a power outage occurs, the power supply unit 13 supplies power required for starting the charging and discharging device 1 from the starting battery. The power supply unit 13 can also charge the starting battery with power from the power system E, the power generation device 23, or the vehicle V.

[0080] The operation unit 14 includes a display, a touch panel with built-in display, and physical buttons, and is exposed from the exterior of the charging and discharging device 1 to receive operations including start (start) and stop (end) from the user. The control unit 11 can control the charging and discharging circuit 10 based on the operations received by the operation unit 14.

[0081] The output unit 15 is a display. The output unit 15 includes a segmented display. The output unit 15 outputs text or images under the control of the control unit 11. As a substitute for the output unit 15, a display of an information terminal device such as a smartphone or a tablet terminal that can be wirelessly connected to the EMS communication unit 12b can be used. In this case, the information terminal device is connected to the charging and discharging device 1 via wireless communication, and can display a screen containing text or images output from the control unit 11. The output unit 15 can also be an LED or a lamp that outputs by lighting up / extinguishing or flashing in a mode corresponding to the instruction from the control unit 11. The output unit 15 can also be a speaker that outputs a stored buzzer sound according to the instruction from the control unit 11. The output unit 15 can also use a display, an LED, and a speaker in combination.

[0082] like Figure 1 and Figure 2 As shown, the charging and discharging circuit 10 of the charging and discharging device 1 configured as described above is connected to the power storage device 30 of the vehicle V through the DC relay 10a and the DC relay 33 on the vehicle V side and the power line PL when the connector 15 is connected to the connector 35 of the vehicle V. Figure 1 and Figure 2 As shown, the charge-discharge circuit 10 is connected to the group of EMS 200, power system E, and load 21 through the power line PL via the parallel-off relay 10b and the distribution board 28. The charge-discharge device 1 controls the transfer of power between the group of power storage device 30, EMS 200, power system E, and load 21 according to the control in EMS 200. When the parallel-off relay 10b, the DC relay 10a, and the DC relay 33 are all in the on state, the charge-discharge circuit 10 can discharge the power storage device 30 to the group of load 21 or charge from the power system E through the power line PL.

[0083] The control unit 11 of the charging and discharging device 1 transmits and receives information with the vehicle-mounted charging and discharging control device 32 and the EMS 200 via the communication unit 12, and controls the charging and discharging circuit 10. The control unit 11 controls charging and discharging between the power system E, the group of loads 21, the power storage device 22 or the power generation device 23, and the vehicle V according to instructions from the EMS 200 that is notified of the state that the vehicle V is connected from the charging and discharging device 1.

[0084] Figure 3 This is a diagram showing an overview of charging and discharging controlled by the EMS 200 . Figure 3 The horizontal axis of represents the passage of time in units of one day, and shows the power consumption of the load 21 , the amount of power generated by the power generation device 23 , and the state of charge and discharge in the power storage device 30 of the vehicle V.

[0085] like Figure 3 As shown, the EMS 200 performs schedule control in a manner such that the power storage device 30 of the vehicle V is charged from the power system E at night when the power purchase price of the power purchased from the power system E is set to be low. Charging may also be performed based on the driving schedule. During the day when the power purchase price of the power purchased from the power system E is set to be high, the EMS 200 supplies power to the load 21 from the power storage device 30 of the vehicle V that has been charged in advance at night. The power from the power generation device 23 that can generate power using sunlight may be rectified and supplied to the load 21, and may be temporarily supplied from the power storage device 30 during a period when the power generation amount of the power generation device 23 is insufficient.

[0086] In particular, when controlling the charge and discharge of power supplied from the power storage device 30 of the vehicle V to the load 21, the EMS 200 requires the charge and discharge device 1 to start or interrupt the power supply from the power storage device 30 of the vehicle V or to adjust the power supply amount according to the operation of the load 21. There is a possibility that the charge and discharge device 1 frequently starts and stops the discharge from the power storage device 30 according to the instructions from the EMS 200. If a connection sequence requiring several seconds is executed between the power storage device 30 of the vehicle V and the on-board charge and discharge control device 32 at each adjustment, the responsiveness is poor and the fluctuation of the operation of the load 21 cannot be fully coped with. Therefore, in order to improve the responsiveness to the instructions from the EMS 200, the charge and discharge device 1 of the present disclosure achieves the improvement of the responsiveness through the control shown below.

[0087] Hereinafter, a process procedure performed by the control unit 11 of the charging and discharging device 1 will be described. Here, it is assumed that the vehicle V is connected to the charging and discharging device 1 via the connector 15 and the connector 35 as described above.

[0088] Figure 4 and Figure 5 1 is a flowchart showing an example of a processing procedure performed by the control unit 11 of the charging and discharging device 1 .

[0089] When the control unit 11 receives a start instruction from the EMS 200, an instruction from the operation unit 14, or power supply from the power supply unit 13 based on a scheduled start and starts (step S101), it notifies the EMS 200 that it is in a state before communication with the vehicle V is established (step S102).

[0090] The control unit 11 executes the prescribed connection sequence to unlock the connector 15 and the connector 35 (step S103), and establishes a communication connection with the on-board charge and discharge control device 32 through the vehicle communication unit 12a (step S104). When the communication connection is established, the control unit 11 obtains the vehicle information of the vehicle V from the on-board charge and discharge control device 32 (step S105). The vehicle information obtained in step S105 includes the identification data of the vehicle V, the vehicle type, the charging capacity and the charging rate (SOC: State Of Charge). The vehicle type is EV, HEV, PHEV, FCV, etc. When the vehicle type is FCV, the vehicle V is a discharge-only vehicle. Whether the vehicle type is EV, HEV or PHEV, there is a situation where only charging can be performed.

[0091] The control unit 11 notifies the EMS 200 that the communication connection with the vehicle V has been completed (step S106). The notification of the completion of the connection with the vehicle V includes the chargeable and dischargeable electric power determined based on the charging capacity and the charging rate.

[0092] The control unit 11 executes a connection sequence with the vehicle-mounted charge and discharge control device 32 and the power storage device 30 to turn on the DC relay 10 a on the charge and discharge device 1 side and the DC relay 33 on the vehicle V side (step S107 ).

[0093] The control unit 11 notifies the EMS 200 of the "connection standby state" in which the DC relay 33 on the vehicle V side is kept on and charging or discharging can be started at any time and the output can be changed (step S108). In the "connection standby state", the control unit 11 makes the inverter in the charge and discharge circuit 10 a gate block and at least makes the parallel-off relay 10b open. In the "connection standby state" of the first embodiment, the control unit 11 performs on / off control on the DC relay 10a in the charge and discharge circuit 10 in the same manner as the DC relay 33 on the vehicle V side.

[0094] In step S108, the control unit 11 may output the fact that the device is in the "connection standby state" to the user through the output unit 15. The output may be in the form of displaying text on the output unit 15, displaying text or images on the user's information terminal device, turning on / off or flashing an LED or lamp of the output unit 15 in a predetermined pattern, or outputting sound through a speaker of the output unit 15.

[0095] The control unit 11 executes control for maintaining the "connection standby state" until receiving a charge / discharge instruction (step S109). The control for maintaining the "connection standby state" will be described in detail later.

[0096] Next, the control unit 11 turns on the parallel-off relay 10b of the charge-discharge circuit 10 as a relay on the charge-discharge device 1 side (the DC relay 10a remains in the on state) (step S110), and starts or continues charging and discharging according to the power setting instructed from the EMS 200 or the operation unit 14 (step S111). In step S111, when charging the power storage device 30 with the minimum power in the "connection standby state", the switching of the parallel-off relay 10b to the on state can be omitted.

[0097] The control unit 11 notifies the EMS 200 of the fact that charging or discharging is in progress from the EMS communication unit 12b (step S112), and sends a message indicating the current value being output (discharging current value or charging current value) from the vehicle communication unit 12a to the vehicle-mounted charge and discharge control device 32 (step S113).

[0098] The control unit 11 determines whether a control instruction is received from the EMS 200 or the operation unit 14 (step S114 ). If it is determined that a control instruction is not received ( S114 : No), the process returns to step S111 .

[0099] When it is determined in step S114 that a control instruction is received (S114: YES), it is determined whether the control instruction is to terminate the charge and discharge control (an end instruction from the EMS 200 or a stop operation performed through the operation unit 14) (step S115).

[0100] When it is determined that the control instruction is not the end of the charge and discharge control (S115: No), the control unit 11 determines whether it is a standby instruction from the EMS 200 (step S116). When it is determined that it is a standby instruction (S116: Yes), the control unit 11 turns off the parallel-off relay 10b of the charge and discharge circuit 10 as a relay on the charge and discharge device 1 side (the DC relay 10a remains in the on state) (step S117), and returns the process to step S109 to transfer to the "connection standby state".

[0101] When it is determined that it is not a standby instruction (S116: No), the control instruction is to set the power or switch between charge and discharge, and therefore the process returns to step S111 according to the control instruction to continue the charge and discharge.

[0102] In step S115, when it is determined that the control instruction is the end of the charge and discharge control (S115: Yes), the control unit 11 starts the end sequence and notifies the vehicle-mounted charge and discharge control device 32 of the stop from the vehicle communication unit 12a (step S301). The control unit 11 disconnects the DC relay 10a and the parallel-off relay 10b of the charge and discharge circuit 10 as relays on the charge and discharge device 1 side (step S302), and cuts off the communication with the vehicle V side (step S303). The control unit 11 unlocks the connector 15 and the connector 35 (step S304), notifies the EMS 200 of the stop state (step S305), and ends the processing. The control unit 11 can also transfer to the shutdown or sleep state.

[0103] exist Figure 5 In the flowchart, the timing of establishing and disconnecting the communication connection with the vehicle-mounted charge and discharge control device 32 on the vehicle V side, and the timing of opening and releasing the locks of the connectors 15 and 35 are exemplified. The order between opening and releasing the connector locks and the communication control can be arbitrarily designed.

[0104] Figure 6 This is a flowchart showing an example of a control procedure for maintaining the “connection standby state”. Figure 6 The processing steps shown in the flowchart are Figure 4 and Figure 5 The details of the processing of step S109 in the flowchart of FIG. Figure 6 The function implemented by the process shown in the flowchart corresponds to the "connection standby state maintaining unit".

[0105] The control unit 11 starts measuring the standby time of the "connection standby state" (step S201).

[0106] The control unit 11 obtains vehicle information including the charging rate of the power storage device 30 from the vehicle-mounted charge and discharge control device 32 (step S202), and determines whether the charging rate is greater than a first charging rate, which is set to a charging rate at which the DC relay 33 is disconnected as determined to be impossible to charge on the vehicle V side (step S203). The first charging rate is, for example, 95%, which is a state close to full charge.

[0107] When it is determined that the current is above the first charging rate (S203: Yes), the control unit 11 sends a message indicating that the current is the minimum value of the discharge current during the discharge to the vehicle-mounted charge and discharge control device 32 (step S204), and advances the process to step S220. The discharge current value is, for example, 1 A. At this time, the DC relay 33 on the vehicle V side is maintained in the on state, but the parallel-off relay 10b of the charge and discharge circuit 10 of the charge and discharge device 1 is not in the on state, so that the discharge from the power storage device 30 to the load 21 side is not actually performed.

[0108] If it is determined in step S203 that the charge rate is less than the first charge rate (S203: No), it is determined whether the charge rate is less than the second charge rate, and the second charge rate is set to a charge rate at which the DC relay 33 is disconnected because the discharge is determined to be impossible (step S205). The second charge rate is, for example, 10%, which is a state where the remaining battery capacity is low.

[0109] When it is determined that the charge rate is below the second charge rate (S205: Yes), the control unit 11 turns on the parallel-off relay 10b of the charge-discharge circuit 10, which is a relay on the charge-discharge device 1 side (step S206). The DC relay 10a remains in the on state, so all the relays of the charge-discharge circuit 10 are turned on. At this time, the control unit 11 starts or continues charging the power storage device 30 with the minimum power (step S207). The control unit 11 sends a message indicating the charging current value to the vehicle-mounted charge-discharge control device 32 (step S208), and advances the processing to step S220.

[0110] The power supply source of the minimum power in step S207 is preferably the power system E. In charging with full charge as the goal, Figure 3 As shown, a time period when the unit price of electricity purchase is high is not preferable. It should be noted that during charging with the minimum electric power, the charging state may not be notified to the EMS 200.

[0111] If it is determined that the second charging rate is exceeded (S205: No), the control unit 11 determines whether the charging started in step S207 is in progress (step S209), and if it is determined that the charging is in progress (S209: Yes), it determines whether the third charging rate has been reached (step S210). The third charging rate is a charging rate slightly higher than the second charging rate, and the value determined as the minimum limit for discharge is preferably, for example, 15%.

[0112] When it is determined that the third charging rate has been reached (S210: Yes), the control unit 11 turns off the parallel-off relay 10b of the charge-discharge circuit 10 as a relay on the charge-discharge device 1 side (the DC relay 10a remains in the on-state), thereby terminating the charging with the minimum power (step S211). The control unit 11 sends a message indicating that the charging current value (e.g., 1A) determined to be the minimum limit during charging to the on-vehicle charge-discharge control device 32 (step S212), and proceeds to step S220.

[0113] When determining that the third charging rate has not been reached (S210: No), the control unit 11 advances the process to step S207 to continue charging (S207), sends a message indicating the charging current value to the vehicle-mounted charge and discharge control device 32 (S208), and advances the process to step S220.

[0114] When it is determined that it is not charging (S209: No), the charging rate is less than the first charging rate and is less than the second charging rate, and charging and discharging can be performed. In this case, the control unit 11 determines whether the measured standby time has reached the specified upper limit time (for example, 10 minutes) or more (step S213). When it is determined that it has not reached the specified upper limit time (S213: No), the processing proceeds to step S212, and a message is sent to the on-board charge and discharge control device 32 in a manner that determines that it is charging (S212), and the standby state is maintained. It should be noted that, in the case where it is determined in step S213 that it has not reached the upper limit time (S213: No), a message can also be sent to the on-board charge and discharge control device 32 in a manner that determines that it is discharging (S204), and the standby state is maintained.

[0115] If it is determined in step S213 that the waiting time is equal to or longer than the upper limit time (S213: Yes), the control unit 11 ends the measurement of the waiting time (step S214), and the process proceeds to step S216. Figure 4 and Figure 5 It should be noted that when the control unit 11 receives an instruction to end the charge and discharge control from the EMS 200 during the processing of steps S201 to S220, the measurement of the standby time is also ended (S214), and the processing is continued to step S301. Figure 4 and Figure 5 Proceed to step S301 in the flowchart.

[0116] The control unit 11 determines whether a charge / discharge instruction is received from the EMS 200 or the operation unit 14 in the "connection standby state" (step S220). If it is determined that a charge / discharge instruction is not received (S220: No), the control unit 11 returns the process to step S202.

[0117] When it is determined that the charge / discharge instruction is received (S220: Yes), the control unit 11 ends the measurement of the waiting time of the "connection waiting state" that has been started (step S221). Thus, the control unit 11 ends the control of maintaining the DC relay 33 on the vehicle V side turned on to enter the "connection waiting state", and returns the processing to step S222. Figure 4 The flowchart returns to step S110.

[0118] As shown in the processing sequence of steps S201 to S221 , the standby state with the vehicle V can be maintained without canceling while waiting for an instruction from the EMS 200 or the operation unit 14 , and an early response to the instruction can be made.

[0119] In the "connection standby state", only the disconnection relay 10b of the charge and discharge circuit 10 as the relay on the side of the charge and discharge device 1 is disconnected, but both the DC relay 10a and the disconnection relay 10b can also be disconnected. In the "connection standby state", both the DC relay 10a and the disconnection relay 10b of the charge and discharge circuit 10 as the relay on the side of the charge and discharge device 1 can be kept connected and the charge and discharge power is "0". In the case of an instruction to charge or discharge, the state in which the charge and discharge output is "0" is also a "connection standby state", in which case, it is possible to respond more quickly to the instruction from the EMS200. It should be noted that this situation is not limited to "0 (zero)" in the control of the transfer of power between the charge and discharge device 1 and the power storage device 30 of the vehicle V, and an output of 50 to 100W can be continued.

[0120] Figure 6 The processing shown in the flowchart is an example. In addition, the control content can also be changed according to the type of vehicle. For example, in the case of FCV, since the power storage device 30 is not charged, in order to maintain the connection of the DC relay 33 on the FCV side, the control unit 11 sends a message indicating the discharge current value judged to be discharged to the on-board charge and discharge control device 32. On the contrary, for the vehicle V set to be unable to discharge, a message indicating the charging current value judged to be charged is sent to the on-board charge and discharge control device 32. It can also be that when charging from the power system E through the charge and discharge control of the EMS200, when the charging current is reduced to a state near zero, that is, near 1A and the efficiency deteriorates, the control unit 11 detects this situation, disconnects the decoupling relay 10b in the charge and discharge device 1, and sends a message indicating the charging current value judged to be charged to the on-board charge and discharge control device 32, and maintains the "connection standby state" until the power is ensured. During this period, the control unit 11 can reduce the chargeable power / dischargeable power of the power storage device 30 of the vehicle V to zero and notify the EMS 200 of the fact, and stand by until power is secured.

[0121] In this way, the charging and discharging device 1 continuously notifies that it is discharging or charging with the minimum power through communication with the on-board charging and discharging control device 32, and continues to maintain the "connection standby state" to prevent the DC relay 33 on the vehicle side from being disconnected due to the control of the on-board charging and discharging control device 32 on the vehicle V side. Figure 3When switching between charging and discharging, and adjusting the voltage or frequency as shown, it is not necessary to execute the connection sequence with the vehicle V every time, and control can be performed at the required response speed. It should be noted that the power consumption on the vehicle V side in the "connection standby state" is greater than the state in which the DC relay 33 is disconnected. Therefore, in order to suppress the power consumption in the standby state where no charging or discharging is performed, the charging and discharging device 1 disconnects the DC relay 33 on the vehicle side, but combined with the control of maintaining the communication connection with the vehicle in an established state, it is also possible to achieve control with low power consumption as much as possible and high responsiveness.

[0122] In the first embodiment, an example of control in which the vehicle V is not scheduled to be used at present and is maintained in a state connected to the charging and discharging device 1 is illustrated. In a case where the charging and discharging device 1 is always connected in communication with the EMS 200 and charging and discharging are repeatedly performed according to instructions from the EMS 200, the lock between the connector 35 of the vehicle V and the connector 15 of the charging and discharging device 1 is maintained in an open state. However, during the period when the instructions from the EMS 200 are given priority, when the user uses the vehicle V, the inconvenience of not being able to use the connectors 15 and 35 because the locks are not released may occur. Therefore, when the charging and discharging device 1 receives a stop operation from the operating unit 14, first, the control is performed in the following manner: it is assumed that the user intends to disconnect the connector 15, and then, instructions including the start instruction from the EMS 200 are not accepted, and the locks of the connectors 15 and 35 are released. As a result, the user can load and unload the connector. Second, when a certain period of time has passed since the stop operation was received by the operation unit 14, the control unit 11 keeps the locks of the connectors 15 and 35 unlocked and transitions to a state in which instructions including a start instruction from the EMS 200 are received. In this case, when an instruction to confirm the connection with the vehicle V is received from the EMS 200, the locks of the connectors 15 and 35 are turned on. In this case, if the user still intends to disconnect the connectors 15 and 35, the stop operation is performed again, and the control unit 11 transitions to the first state in which the stop operation is received.

[0123] (Variation Example)

[0124] In the above-mentioned embodiment 1, the processing for maintaining the connection standby state in which the relay on the vehicle side is connected is described. In a modified example, the charging and discharging device 1 and the vehicle V can also standby in a "disconnected standby state" which is different from the "connected standby state". The "disconnected standby state" is a state in which the communication connection with the vehicle-mounted charging and discharging control device 32 is cut off, and it is a state in which charging and discharging cannot be started if the prescribed connection sequence is not executed again. The "disconnected standby state" is a state in which it has been confirmed that the lock between the connector 35 of the vehicle V and the connector 15 of the charging and discharging device 1 is open and maintained open. That is, with respect to the "disconnected standby state" and the "stop state", the connection and disconnection of the connector are different degrees. As a state of control of the charging and discharging device 1 and the vehicle V, it is equivalent to the stop state.

[0125] exist Figure 4-Figure 6 In the processing steps shown in the flowchart of , when a charge / discharge instruction is received in the "connection standby state" (S220: Yes), charge / discharge is started (S111), and when the standby time exceeds the upper limit time, the sequence to the stop state is executed (S301-S305). In the modified example, the charge / discharge device 1 is controlled in the following manner: in addition to executing charge / discharge, the "connection standby state" is not only transferred to the stop state, but also transferred to the "disconnection standby state".

[0126] Figure 7 1 is a flowchart showing an example of a control procedure for changing the state between the "connection standby state" and the "disconnection standby state". Figure 7 The processing steps shown in the flowchart are Figure 6 The steps shown in the flowchart are alternative to those shown in the flowchart, but with Figure 6 The steps shown in the flowchart are performed in combination.

[0127] The control unit 11 starts measuring the standby time of the "connection standby state" (step S901).

[0128] The control unit 11 acquires vehicle information including the charging rate of the power storage device 30 from the vehicle-mounted charge and discharge control device 32 (step S902 ), and stores the information in advance as the charging rate at the standby start time (step S903 ).

[0129] The control unit 11 determines whether the standby time has passed a prescribed time (for example, 10 minutes) (step S904). When it is determined that the prescribed time has passed (S904: Yes), the control unit 11 ends the measurement of the standby time (step S905). The control unit 11 disconnects the DC relay 10a and the parallel disconnection relay 10b of the charge and discharge circuit 10 as relays on the charge and discharge device 1 side (step S906), and cuts off communication with the vehicle V side (step S907). The control unit 11 notifies the on-board charge and discharge control device 32 of the transition to the "isolated standby state" from the vehicle communication unit 12a (step S908). In this case, the control unit 11 ends the maintenance processing of the "connected standby state" without returning to Figure 4 and Figure 5 , and transitions to the "isolation standby state" through steps S905-S908.

[0130] When the control unit 11 determines in step S904 that the standby time has not exceeded the predetermined time (S904: No), the control unit 11 obtains the charging rate of the power storage device 30 from the vehicle-mounted charge and discharge control device 32 (step S909). The control unit 1 determines whether the acquired charging rate is less than or equal to a second charging rate, which is set to a charging rate at which it is determined that the vehicle V cannot be discharged and the DC relay 33 is turned off (step S910).

[0131] When it is determined that the charging rate is equal to or lower than the second charging rate (S910: YES), the control unit 11 advances the process to step S905. In this case, the charging and discharging device 1 transitions to the "shutdown standby state".

[0132] When determining that the charging rate is not less than the second charging rate ( S910 : No), the control unit 11 determines whether the charging rate acquired in step S909 has decreased by a predetermined ratio relative to the charging rate at the standby start time (step S911 ).

[0133] When it is determined in step S911 that the charging rate has not decreased by the predetermined ratio ( S911 : NO), the control unit 11 advances the process to step S912 .

[0134] When it is determined that the charging rate has decreased by a predetermined ratio (S911: Yes), the control unit 11 advances the process to step S905. In this case, the charging and discharging device 1 also transitions to the "shutdown standby state".

[0135] The control unit 11 determines whether a stop instruction is received from the EMS 200 or the operation unit 14 in the "connection standby state" (step S912). If it is determined that a stop instruction is received (S912: Yes), the control unit 11 ends the measurement of the standby time of the "connection standby state" that has started (step S913), and returns the process to step S914. Figure 4 and Figure 5 The process proceeds to step S301 of the start and end sequence in the flowchart of FIG. 1. When an abnormal stop is detected, the control unit 11 executes an abnormal stop process to transition from the "connection standby state" to another state or the abnormal stop state.

[0136] In step S912 , when it is determined that the stop instruction has not been received ( S912 : NO), the control unit 11 returns the process to step S904 to maintain the connection standby state.

[0137] The control unit 11 Figure 7 In addition to the conditions shown in the flowchart, not only a "stop instruction" but also a transition instruction to the "isolation standby state" can be received from EMS200, and in this case, it can also transfer to the "isolation standby state".

[0138] As described above, when the control unit 11 detects a situation in which it can be inferred that it is not necessary to maintain the connection standby state, that is, a state in which the responsiveness of charge and discharge is improved, it is preferable to shift to a state in which the communication connection is disconnected.

[0139] The charging and discharging device 1 can also return from the disconnected standby state to the connected standby state. The control unit 11 of the charging and discharging device 1 that has changed to the "disconnected standby state" executes the connection sequence to temporarily change to the connected standby state when there is a charge and discharge instruction from the EMS 200, and then starts charging and discharging. The control unit 11 can execute the connection sequence to change to the "connected standby state" when the EMS 200 instructs it to change to the "connected standby state", that is, to a state where charging and discharging can be performed immediately, in the disconnected standby state.

[0140] Regarding disconnection of the communication connection, even if it is not the "connection standby state", it is necessary to avoid maintaining the communication connection for a long time, such as 24 hours. Therefore, when it is detected that the communication connection is established for a time longer than that defined as a long time, it is desirable that the control unit 11 disconnects the communication connection.

[0141] (Implementation Method 2)

[0142] In the second embodiment, it is considered that a plurality of electric vehicles, namely, vehicles V manufactured by different manufacturers are combined with various EMS 200 to further perform control for protecting the charging and discharging circuit. The charging and discharging device 1 coordinates the control of the EMS 200 and the vehicle V, and when a situation such as the DC relay 33, 10a and the disconnection relay 10b are repeatedly turned on and off occurs, it changes to a protection state that does not respond to the instruction from the EMS 200.

[0143] The hardware configuration of the charge and discharge device 1 and EMS 200 in the second embodiment is the same as that in the first embodiment, so the same reference numerals are used and detailed description is omitted. Next, control of the charge and discharge device 1 in the second embodiment for preventing repeated switching of the DC relays 33, 10a and the parallel-off relay 10b between on and off is described.

[0144] The case where the EMS 200 performs control such as charging the charging rate (SOC) of the power storage device 30 of the vehicle V connected via the charging and discharging device 1 until the charging rate is determined to be fully charged is described as an example. In the discharge device 1 that has received the charging instruction from the EMS 200, the control unit 11 performs a predetermined connection sequence by communicating with the vehicle-mounted charge and discharge control device 32 via the communication line CL and adjusting the output in the power line VPL. When the preparation of the output necessary for charging and discharging between the charging and discharging device 1 and the power storage device 30 is completed through the connection sequence, charging is started.

[0145] Depending on conditions such as temperature, the onboard charge and discharge control device 32 may determine that further charging will deteriorate the power storage device 30 before the charge rate (SOC) in the power storage device 30 reaches a predetermined first ratio for determining that the power storage device 30 is fully charged, and may stop charging. In this case, the onboard charge and discharge control device 32 turns off the DC relay 33 of the vehicle V to stop charging.

[0146] Even if charging is stopped by vehicle-mounted charge and discharge control device 32 , EMS 200 may output a charging instruction until the charging rate of power storage device 30 obtained via charge and discharge device 1 reaches the full charge capacity or the first rate.

[0147] When a charging instruction is output from EMS 200, if it is a conventional charging and discharging device, charging is restarted even in a state where the DC relay 33 of the vehicle V is disconnected by the stop from the vehicle-mounted charging and discharging control device 32. In order to start charging, a predetermined connection sequence including a step of turning on the DC relay 33 is executed, but since it is determined that the power storage device 30 is in a state where it cannot be further charged, the vehicle-mounted charging and discharging control device 32 executes a charging stop control again, turns off the DC relay 33, and stops charging. Since the charging rate of the power storage device 30 has not reached the full charge capacity or the first rate, a charging instruction is output from EMS 200 again.

[0148] Thus, even if the vehicle-mounted charge and discharge control device 32 determines that charging is impossible, when a charging instruction is sent from the EMS 200, the DC relay 33 on the vehicle V side is repeatedly opened and the DC relay 33 is repeatedly closed by the charging start procedure based on the charging instruction. The repeated opening and closing of the DC relay 33 promotes the deterioration of the DC relay 33.

[0149] Therefore, when the charging and discharging device 1 of embodiment 2 is in a situation where the DC relay 33 is repeatedly turned on and off based on the control in the vehicle-mounted charging and discharging control device 32 and the instruction of EMS200, the charging and discharging device 1 of embodiment 2 ignores the instruction from EMS200 and changes to a protection state that does not respond to the instruction, or at least does not perform the protection state of turning on and off the DC relay 33.

[0150] Figure 8 and Fig. 9 2 is a flowchart showing an example of a transition procedure to the protection state of the charge and discharge device 1. The control unit 11 of the charge and discharge device 1 executes the following processing in a state of being communicatively connected to the EMS 200 via the EMS communication unit 12b.

[0151] When the control unit 11 receives a start instruction from the EMS 200, an instruction from the operation unit 14, or starts up by power supply from the power supply unit 13 at the start of a schedule (step S401), it notifies the EMS 200 that it is in a state before communication with the vehicle V is established (step S402).

[0152] The control unit 11 executes the prescribed connection sequence to open the locks of the connector 15 and the connector 35 (step S403), and establishes a communication connection with the on-board charge and discharge control device 32 through the vehicle communication unit 12a (step S404). When the communication connection is established, the control unit 11 obtains the vehicle information of the vehicle V from the on-board charge and discharge control device 32 (step S405). The vehicle information obtained in step S405 includes at least the charging capacity and the charging rate (SOC: State Of Charge). The vehicle information may also include identification data or vehicle type of the vehicle V. The vehicle type is EV, HEV, PHEV, FCV, etc. When the vehicle type is FCV, the vehicle V is a discharge-only vehicle. There are cases where the vehicle type is EV, HEV or PHEV and only charging is possible.

[0153] The control unit 11 notifies the EMS 200 that the communication connection with the vehicle V has been completed (step S406). The notification of the completion of the connection with the vehicle V includes the chargeable and dischargeable electric power determined based on the charging capacity and the charging rate.

[0154] The control unit 11 determines whether a control instruction is received from the EMS 200 (step S407). If it is determined that the EMS communication unit 12b has not received a control instruction from the EMS 200 (S407: No), the control unit 11 returns the process to step S407 after a predetermined standby time has passed. The control unit 11 enters a standby state until a control instruction is received.

[0155] When the control unit 11 determines in step S407 that a control instruction has been received (S407: Yes), it determines whether the control instruction is a charge instruction or a discharge instruction (step S408).

[0156] If it is determined in step S408 that it is a charge instruction or a discharge instruction (S408: Yes), the control unit 11 executes the subsequent connection sequence with the vehicle-mounted charge and discharge control device 32 and the power storage device 30 to turn on the DC relay 33 on the vehicle V side (step S409). The control unit 11 turns on the DC relay 10a and the parallel-off relay 10b of the charge and discharge circuit 10 (step S410) to start or continue charging and discharging (step S411).

[0157] The control unit 11 obtains state information including the charging rate related to the power storage device 30 from the on-board charge and discharge control device 32 through the vehicle communication unit 12a (step S412). In step S412, when charging is stopped by the control of the on-board charge and discharge control device 32, the control unit 11 can obtain the state information of charging stop by receiving the notification of the end from the on-board charge and discharge control device 32.

[0158] The control unit 11 determines whether a control instruction is received from the EMS 200 or the operation unit 14 (step S413). When charging is stopped by the control of the on-board charge and discharge control device 32, the DC relay 33 on the vehicle V side is turned off. In order to turn on the DC relay 33 again, the charge and discharge device 1 requests a predetermined connection sequence from the on-board charge and discharge control device 32. When it is determined in step S413 that a control instruction is not received (S413: No), the process returns to step S411.

[0159] When it is determined in step S413 that a control instruction is received (S413: YES), it is determined whether the control instruction is to end the charge and discharge control (an end instruction from the EMS 200 or an operation of a stop button by the operation unit 14) (step S414).

[0160] When it is determined that the control instruction is not the end of the charge and discharge control (S414: No), the control unit 11 determines whether it is a standby instruction from the EMS 200 (step S415). When it is determined that it is a standby instruction (S415: Yes), the control unit 11 turns off the parallel-off relay 10b of the charge and discharge circuit 10 (the DC relay 10a remains in the on state) (step S416), and returns the process to step S407, returning to the standby state.

[0161] If it is determined that it is not a standby instruction (S415: No), the control instruction is to switch between charging and discharging. The control unit 11 determines whether to transition to the protection state for protecting the relay (step S417). The determination of transition to the protection state in step S417 will be described in detail later.

[0162] When it is determined in step S417 that the state has changed to the protection state (S417: Yes), the control unit 11 turns off the DC relay 10a and the parallel-off relay 10b of the charge-discharge circuit 10 (step S418). The control unit 11 disconnects the vehicle V (step S419), notifies the EMS 200 of the change to the protection state through the EMS communication unit 12b (step S420), and ends the process while keeping the lock of the connector open. The notification of step S420 may be omitted.

[0163] In this case, the control unit 11 changes to the protection state. In the protection state, the control unit 11 receives instructions from the EMS 200 through the EMS communication unit 12b, but ignores the instructions and does not respond to the instructions. In the protection state, the control unit 11 at least does not perform the connection and disconnection of the DC relay 33 of the vehicle V. In the protection state, the control unit 11 can also forcibly shut down the device. When shutting down, the connector lock is released and the communication connection with the EMS 200 is also cut off.

[0164] The control unit 11 temporarily shuts down the charging and discharging device 1 and then restarts it to restore it from the protection state, or Fig.12 The control unit 11 in the shutdown state intermittently activates the EMS communication unit 12b, and restarts the EMS communication unit 12b when confirming that the activation instruction has been received from the EMS 200.

[0165] When it is determined in step S417 that there is no transition (S417: No), the control unit 11 returns the process to step S411 to continue charging and discharging according to the control instruction.

[0166] If it is determined in step S414 that the control instruction is the end of the charge and discharge control (S414: Yes), the control unit 11 starts the end sequence and notifies the vehicle-mounted charge and discharge control device 32 of the stop from the vehicle communication unit 12a (step S421). The control unit 11 turns off the DC relay 10a and the parallel-off relay 10b of the charge and discharge circuit 10 (step S422), and cuts off the communication with the vehicle V side (step S423). The control unit 11 releases the lock of the connector 15 and the connector 35 (step S424), notifies the EMS 200 of the stop state (step S305), and ends the processing. The control unit 11 shifts to the shutdown or sleep state.

[0167] Fig.10 This is a flowchart showing an example of a process procedure for determining whether to transition to the protection state. Fig.10 Flowchart and Figure 8 and Fig. 9 The details of step S417 in the processing steps shown in the flowchart correspond to.

[0168] The control unit 11 determines the interval between the charging instruction or discharging instruction received in step S408 and the timing of receiving the last charging instruction or discharging instruction (step S701). The control unit 11 determines whether the determined interval is within a predetermined interval and the number of receptions is greater than or equal to a predetermined number (step S702).

[0169] In step S701 and step S702 , the control unit 11 counts each time a charge instruction or a discharge instruction is received, and resets the count to zero when a period corresponding to a predetermined interval has passed since the last charge instruction or the discharge instruction was received until the next charge instruction or the discharge instruction is received.

[0170] When the control unit 11 determines that the determined interval is within the prescribed interval and the number of receptions is greater than the prescribed number of times (S702: Yes), it determines that the state should be changed to the protection state (step S703), and changes the process to Fig. 9 Proceed to step S418 in the flowchart.

[0171] In step S702 , the control unit 11 may determine whether the same instruction of either the charge instruction or the discharge instruction is repeatedly received within a predetermined period (predetermined interval×predetermined number of times), and determine to transition to the protection state if the same instruction is repeatedly received within the predetermined period.

[0172] In step S702 , the control unit 11 determines whether the charging instruction and the discharging instruction are substantially alternately received within a predetermined period (predetermined interval×predetermined number of times), and if they are alternately received within the predetermined period, it can be determined that the state is shifted to the protection state.

[0173] In step S702, when it is determined that the interval determined in step S701 is not within the prescribed interval or the number of receptions is less than the prescribed number (S702: No), the control unit 11 determines whether status information indicating the charging stop state is obtained by the vehicle-mounted charging and discharging control device 32 (step S704).

[0174] On the vehicle V side, when the vehicle-mounted charge and discharge control device 32 determines that the charging rate of the power storage device 30 has reached or exceeded the first ratio of the full charge capacity and autonomously switches the DC relay 33 to OFF, it may notify the charge and discharge device 1 to stop charging. In this case, the control unit 11 may Fig. 9 In step S412 shown in the flowchart of FIG. 1 , it is understood that the charging is stopped by the control on the vehicle V side.

[0175] When it is determined in step S704 that a state indicating charging stop is acquired (S704: YES), the control unit 11 determines whether the charging instruction or the discharging instruction received in step S408 is repeatedly received a plurality of times within a predetermined period (step S705).

[0176] In step S705, when it is determined that the vehicle-mounted charge and discharge control device 32 has switched to the charging stop state and the same instruction as a charge instruction or a discharge instruction has been received repeatedly within a predetermined period (S705: Yes), the control unit 11 determines that the state is switched to the protection state (S703). After the determination, the control unit 11 switches the processing to Fig. 9 Proceed to step S418 in the flowchart.

[0177] If the result of the determination in either step S704 or step S705 is negative (S704: No or S705: No), the control unit 11 determines that the state should not be changed to the protection state (step S706), and the process is changed to Fig. 9 Step S411 in the flowchart returns.

[0178] Fig.11 This is a flowchart showing another example of the determination process procedure of whether to shift to the protection state. Fig.11 Flowchart and Figure 8 and Fig. 9 The details of step S417 in the processing steps shown in the flowchart correspond to.

[0179] Control unit 11 determines whether a charging instruction is received from EMS 200 in step S413 when the charging rate in the state information of power storage device 30 acquired in step S412 is equal to or higher than a predetermined first ratio of the full charge capacity determined as fully charged (step S711 ).

[0180] If it is determined in step S711 that a charging instruction has been received even though the charging rate is at least the predetermined first rate (S711: Yes), the control unit 11 determines that the state should be changed to the protection state (step S712), and the process is changed to the protection state. Fig. 9 Proceed to step S418 in the flowchart.

[0181] In step S711, when it is determined that a charging instruction is received again even if it is above the prescribed first ratio, since the charging rate determined as full charge on the vehicle V side has been reached, it is estimated that the on-vehicle charge and discharge control device 32 will control the charging to stop. Nevertheless, in the case where the charging instruction is resent from the EMS 200, it is predicted that the charging stop process in the on-vehicle charge and discharge control device 32 and the sending of the charging instruction from the EMS 200 will be repeated in the future. As a result, it is predicted that the DC relay 33 in the vehicle V and the DC relay 10a and the disconnection relay 10b in the charging and discharging device 1 will be repeatedly turned on and off. Therefore, in such a case, the control unit 11 of the charging and discharging device 1 of the second embodiment changes to a protection state to prevent the charging instruction from being repeated and sent from the EMS 200.

[0182] When it is determined in step S711 that the charging rate is not above the prescribed first ratio or no charging instruction is received (S711: No), the control unit 11 determines whether a discharge instruction is received from the EMS 200 in step S413 when the charging rate acquired in step S412 is below the prescribed second ratio of the full charge capacity judged to be empty (lower limit) (step S713).

[0183] If it is determined in step S713 that a discharge instruction has been received even though the charge rate is less than the predetermined second rate (S713: Yes), the control unit 11 determines that the state should be changed to the protection state (S712), and the process is changed to Fig. 9 Proceed to step S418 in the flowchart.

[0184] In step S713, when it is determined that a discharge instruction is received again even if the discharge instruction is less than the prescribed second ratio, since the charging rate is reached at which the charging capacity is determined to be close to the lower limit on the vehicle V side, it is estimated that the on-vehicle charge and discharge control device 32 will control the discharge to stop. Nevertheless, when the discharge instruction is resent from the EMS 200, it is predicted that the discharge stop process in the on-vehicle charge and discharge control device 32 and the sending of the discharge instruction from the EMS 200 will be repeated in the future. As a result, it is predicted that the DC relay 33 in the vehicle V and the DC relay 10a and the disconnection relay 10b in the charge and discharge device 1 will be repeatedly turned on and off. Therefore, in such a case, the control unit 11 of the charge and discharge device 1 of the second embodiment changes to the protection state in a manner that the discharge instruction is repeatedly sent and not sent from the EMS 200.

[0185] If it is determined in step S713 that the charging rate is not less than the predetermined second rate or that no discharge instruction has been received (S713: No), the control unit 11 determines not to change to the protection state (step S714) and changes the process to Fig. 9 Step S411 in the flowchart returns.

[0186] Regarding whether to change to the protection state in step S117, the control unit 11 executes Fig.10 The process steps shown in the flowchart and Fig.11 The processing steps shown in the flowchart are judged by both or either one.

[0187] Fig.12 The control unit 11 continuously executes the following processing when the communication connection with the EMS 200 is maintained by the EMS communication unit 12 b , the connector lock is kept on, and the protection state ignores the instruction from the EMS 200 .

[0188] The control unit 11 determines whether a predetermined waiting time has elapsed after the transition to the protection state (step S801 ).

[0189] The control unit 11 intermittently communicates with the vehicle-mounted charge and discharge control device 32 of the vehicle V via the vehicle communication unit 12 a (step S802 ), and acquires the charging rate of the power storage device 30 (step S803 ).

[0190] The control unit 11 determines whether the acquired charging rate is higher than the specified second ratio and lower than the specified first ratio (step S804). If it is determined that the acquired charging rate is higher than the specified first ratio or lower than the specified second ratio (S804: No), the control unit 11 returns the process to step S801.

[0191] If the acquired charging rate is determined to be higher than the second ratio and lower than the first ratio ( S804 : Yes), the control unit 11 determines to return from the protection state (step S805 ) and terminates the process. Thereafter, the control unit 11 executes control corresponding to the instruction from the EMS 200 .

[0192] If it is determined in step S801 that the predetermined standby time has not elapsed (S801: No), the control unit 11 determines whether a stop operation has been received through the operation unit 14 (step S806). If it is determined that a stop operation has been received (S806: Yes), the control unit 11 advances the process to step S805, recovers from the protection state, and executes the process corresponding to the operation.

[0193] When it is determined in step S806 that the stop operation has not been received (S806: No), the control unit 11 determines whether a restoration instruction (reset is also acceptable) has been received from the EMS 200 via the EMS communication unit 12b (step S807).

[0194] When it is determined in step S807 that a restoration instruction has been received from the EMS 200 (S807: YES), the control unit 11 advances the process to step S805, restores from the protection state, and executes a process corresponding to the instruction (connection sequence or end sequence).

[0195] When it is determined in step S807 that the instruction to restore has not been received (S807: NO), the control unit 11 returns the process to step S801.

[0196] pass Fig.10 or Fig.11 According to the judgment step shown in the flowchart, when the DC relay 33 in the vehicle V and the DC relay 10a and the parallel-off relay 10b in the charging and discharging device 1 are actually turned on and off repeatedly, or when it is predicted that they will be turned on and off with a high probability, it is judged that the protection state is changed. That is, when the control instruction from the EMS 200 is not suitable for the control in the vehicle-mounted charging and discharging control device 32, the protection state is changed to not respond to the instruction from the EMS 200 for at least a certain period of time, so that the charging and discharging circuit can be protected.

[0197] Furthermore, when the control unit 11 is notified of a stop due to an abnormality by the vehicle communication unit 12 a while executing a predetermined connection sequence with the vehicle-mounted charge and discharge control device 32 in accordance with a control instruction from the EMS 200 , the control unit 11 may control the transition to the protection state.

[0198] Furthermore, the control unit 11 of the charging and discharging device 1 returns from the protection state after confirming that the charging rate of the power storage device 30 of the vehicle V has returned to a chargeable state or a dischargeable state. This can prevent the DC relays 33, 10a and the disconnect relay 10b from being repeatedly switched on and off.

[0199] (Implementation 3)

[0200] In the third embodiment, the state transitions to the protection state under the transition condition corresponding to the type of the vehicle V connected by the connector 15 or 35 via the vehicle communication unit 12 a .

[0201] The hardware structure of the charge and discharge device 1 in Embodiment 3, and the connection structure of the ESM 200 connected to the charge and discharge device and the vehicle-mounted charge and discharge control device 32 are the same as those in Embodiment 1. The same reference numerals are used for the structures of the charge and discharge device 1 in Embodiment 3 that are common to those in Embodiment 1, and detailed descriptions thereof are omitted.

[0202] In the third embodiment, the charging and discharging device 1 stores the transition conditions for each vehicle type in advance in the memory built into the control unit 11 for the vehicles V to be charged and discharged. For example, the transition conditions are stored as follows: for a vehicle V of the first vehicle type, Fig.10 The determination process shown in the flowchart of FIG. 1 is performed for the vehicle V of the second vehicle type. Fig.11 In addition, it can also be stored as: for the vehicle V of the third vehicle type, Fig.11 The first ratio relative to the fully charged capacity in the flowchart is 85%, and the first ratio is 90% for the fourth vehicle type vehicle V. The above-mentioned transition conditions can be stored based on the criteria for judging as fully charged or the criteria for judging as empty (lower limit) provided by the manufacturer of each vehicle V, and can also be made by the charging and discharging device 1 through experiments performed with each vehicle V.

[0203] Fig.13 and Fig.14 : is a flowchart showing an example of a transition procedure of the charge and discharge device 1 to the protection state in the third embodiment. Fig.13 and Fig.14 The processing steps in the flowchart of Implementation 2 Figure 8 and Fig. 9 The steps that are common to the processing steps shown in the flowchart are marked with the same step numbers and the detailed description is omitted.

[0204] In the third embodiment, when the control unit 11 acquires the vehicle information in step S405 ( S405 ), based on the identification information of the vehicle type included in the vehicle information, the control unit 11 reads the transition condition corresponding to the vehicle type from the memory (step S426 ).

[0205] If it is determined in step S415 that the vehicle is not in the standby state (S415: No), the control unit 11 determines whether to change to the protection state based on the transition condition corresponding to the vehicle type read in step S426 (step S427). The details of the determination in step S427 may be Fig.10 The processing steps shown in the flowchart and Fig.11 Both or one of the processing steps shown in the flowchart.

[0206] Information for identifying the type of vehicle is obtained, and judgment is made based on the transition conditions corresponding to the type of vehicle. This enables appropriate coordination between the control content of charging and discharging on the vehicle V side that varies according to the type of vehicle and the instructions from various EMS200, and can protect not only the vehicle V but also the charging and discharging circuit 10 of this device.

[0207] The embodiments disclosed above are illustrative in all points and are not restrictive. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are included.

[0208] Explanation of symbols:

[0209] 1. Charging and discharging device

[0210] 10. Charging and discharging circuit

[0211] 10A DC relay

[0212] 10b De-energizing relay

[0213] 11. Control Unit

[0214] 12 Ministry of Communications

[0215] 12a Vehicle Communication Department

[0216] 12b EMS Communication Department

[0217] 15 Connectors

[0218] 1P Computer Program

[0219] 200 EMS

[0220] 21 Load

[0221] 30 Power storage device

[0222] 32. On-vehicle charging and discharging control device

[0223] 33DC Relay

[0224] 35 Connectors

[0225] PL Power Line

[0226] V Vehicle

[0227] VPL Power Line

Claims

1. A charging and discharging device comprising: A connector connected to a vehicle-mounted power line, wherein the vehicle-mounted power line is connected to a battery provided in the vehicle; a control unit that controls charging and discharging of the storage battery; and a communication unit that is communicatively connected to a vehicle-mounted control device that switches on and off a relay installed on the vehicle side of the vehicle-mounted power line, wherein: The control unit sends and receives messages to and from the vehicle-mounted control device via the communication unit based on a predetermined timing. After switching the relay on the vehicle side to on based on the prescribed timing, the control unit sends a message indicating that charging or discharging is in progress to the vehicle-mounted control device while the battery is not being charged or discharged, thereby maintaining the vehicle-side relay in a connection standby state in on-state.

2. A charging and discharging device, comprising: A connector connected to a vehicle-mounted power line, wherein the vehicle-mounted power line is connected to a battery provided in the vehicle; a control unit that controls charging and discharging of the storage battery; and a communication unit that is communicatively connected to a vehicle-mounted control device that switches on and off a relay installed on the vehicle side of the vehicle-mounted power line, wherein: The control unit sends and receives messages to and from the vehicle-mounted control device via the communication unit based on a predetermined timing. After the control unit switches the relay on the vehicle side to on based on the predetermined timing, the control unit maintains the communication connection with the vehicle and maintains the connection standby state in which the relay on the vehicle side is kept on even when the battery is not being charged or discharged.

3. A charging and discharging device comprising: A connector connected to a vehicle-mounted power line, wherein the vehicle-mounted power line is connected to a battery provided in the vehicle; A control unit that controls charging and discharging of the storage battery; a communication unit that is communicatively connected to an on-vehicle control device that switches on and off a relay installed on the vehicle side of the on-vehicle power line; as well as A charge and discharge circuit includes a relay for switching on and off the transfer of power between the storage battery and a commercial power source or a load, wherein: The control unit sends and receives messages to and from the vehicle-mounted control device via the communication unit based on a predetermined timing. After the control unit switches the relay on the vehicle side to on based on the predetermined timing, the control unit maintains the connection standby state in which the relay on the vehicle side is on while the battery is not being charged or discharged. The relay of the charging and discharging circuit includes: a disconnecting relay for switching on and off the power exchange between the charging and discharging circuit and the commercial power supply; and a device-side relay installed between the charging and discharging circuit and the connector, In the connection standby state, the parallel-off relay is turned off and the device-side relay is turned on.

4. The charge and discharge device according to claim 3, wherein: The control unit turns off the relay on the charge / discharge circuit side to maintain the connection standby state, and transmits a message indicating the charge / discharge current value of the lower limit value determined as being in charge or in discharge from the communication unit to the vehicle-mounted control device.

5. The charge and discharge device according to claim 4, wherein: The control unit determines whether the charging rate of the storage battery is equal to or higher than a predetermined first charging rate for determining that the storage battery is fully charged in order to maintain the connection standby state. The control unit transmits a message indicating a discharge current value determined to be in discharge to the in-vehicle control device when the control unit determines that the charge rate of the storage battery is equal to or higher than a first charge rate.

6. The charge and discharge device according to claim 4, wherein: The control unit determines whether the charging rate of the storage battery is lower than or equal to a predetermined second charging rate determined as a lower limit in order to maintain the connection standby state. When the control unit determines that the charging rate of the storage battery is equal to or higher than the second charging rate, the control unit turns on the relay of the charge-discharge circuit to charge the storage battery with power from the commercial power supply until the charging rate of the storage battery reaches a predetermined third charging rate. The control unit transmits a message indicating a charging current value to the in-vehicle control device.

7. The charge and discharge device according to any one of claims 1 to 6, wherein: The charging and discharging device further includes an output unit configured to output text, lighting / extinguishing of light, blinking, or sound indicating that the device is in the connection standby state while the control unit maintains the connection standby state.

8. The charge and discharge device according to any one of claims 1 to 6, wherein: In order to maintain the connection standby state, the control unit disconnects the relay on the vehicle side to cut off the communication connection based on the communication unit when at least any one of the following conditions is met: whether a specified time has passed since the start of maintaining the connection standby state, whether the charging rate of the battery is below a specified second charging rate judged as a lower limit, or whether the charging rate of the battery has decreased by more than a specified proportion since the start of maintaining the connection standby state.

9. The charge and discharge device according to any one of claims 1 to 6, wherein: The charging and discharging device further includes a host control communication unit that exchanges data with a host control device that instructs charging and discharging of the storage battery of the vehicle. The control unit determines whether to shift to a protection state for protecting the relay on the vehicle side based on information on the battery acquired from the vehicle-mounted control device via the communication unit and an instruction from the host control device received via the host control communication unit.

10. The charge and discharge device according to claim 9, wherein: In the protection state, the control unit does not respond to a charge instruction or a discharge instruction from the host control device, or returns a negative response to the instruction.

11. A charge and discharge control method, wherein a charge and discharge device controls the charge and discharge of a storage battery installed in a vehicle, the charge and discharge device having a connector connected to a vehicle power line, the vehicle power line being connected to the storage battery, wherein: The charging and discharging device is communicatively connected to a vehicle-mounted control device, and the vehicle-mounted control device switches on and off a relay installed on the vehicle side of the vehicle-mounted power line. The charging and discharging device and the vehicle-mounted control device send and receive messages based on a specified timing. After the charge and discharge device switches the relay on the vehicle side to on based on the specified timing, while the battery is not being charged or discharged, the charge and discharge device sends a message indicating that charging or discharging is in progress to the vehicle-mounted control device, thereby maintaining the relay on the vehicle side in a connected standby state.

12. A storage medium, which is a computer-readable storage medium storing a computer program, wherein the computer program causes the computer to execute the following processing, wherein the computer is mounted on a charging and discharging device, the charging and discharging device has a connector connected to a vehicle-mounted power line, the vehicle-mounted power line is connected to a battery installed in a vehicle, and the charging and discharging device has a communication unit that is communicatively connected to a vehicle-mounted control device, and the vehicle-mounted control device switches on and off a relay installed on the vehicle side of the vehicle-mounted power line, wherein: The processing includes: transmitting and receiving messages between the charging and discharging device and the vehicle-mounted control device through the communication unit based on a predetermined timing; and After the vehicle-side relay is switched on based on the prescribed timing, a message indicating that charging or discharging is in progress is sent to the vehicle-mounted control device while the battery is not being charged or discharged, and the vehicle-side relay is maintained in a connection standby state in which it is turned on.

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