Power management system and electric vehicle

Abstract

To enable power supply from a power storage device of an electric vehicle conveying a load at least in a facility, to the facility while smoothly managing the electric vehicle.SOLUTION: A power management system according to the present disclosure manages power exchange between power storage devices of a plurality of electric vehicles conveying loads and a charging / discharging device connected to a power system of a facility. The power management system includes a vehicle management device. When power supply from at least one of the electric vehicles to the power system is requested, the vehicle management device selects an electric vehicle having a capacity for discharge from the power storage device on the basis of the SOC of the power storage devices of the electric vehicles and the weights of the loads on the electric vehicles. Further, the vehicle management device gives a command for discharge from the storage device to the power system, to the selected electric vehicle. As a result, while the electric vehicles conveying loads are smoothly managed, power can be supplied from the power storage devices of the electric vehicles to the power system.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a power management system that manages the exchange of power between a power storage device of an electric vehicle that transports cargo and a charging / discharging device connected to a facility's power grid, and to an electric vehicle that transports cargo at least within a facility. [Background technology]

[0002] A conventionally known energy management device includes a remaining charge receiving unit that acquires the remaining charge of a storage battery installed on an aircraft, and a plan creation unit that creates a power usage plan that is a plan for using power at an airport based on the remaining charge of the storage battery of the aircraft (see, for example, Patent Document 1). The plan creation unit of this energy management device creates an operation plan for electric vehicles used for work at the airport based on the power usage plan. Furthermore, the plan creation unit selects electric vehicles to be charged with power from the storage battery of the aircraft or another charging device based on the distance between the electric vehicles and the parking location, the SOC of the storage battery of the electric vehicles, the work time, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-045029 Summary of the Invention [Problem to be solved by the invention]

[0004] If the batteries of electric vehicles are connected to an airport's power grid via a charging / discharging device, it would be possible to balance the supply and demand of electricity at the airport by supplying power from the batteries of the electric vehicles to the power grid. However, Patent Document 1 does not disclose supplying power from the batteries of electric vehicles to the airport's power grid. As a result, at airports where the above-mentioned energy management device is used, electric vehicles that supply power to the power grid may not be selected appropriately, which could cause problems in the operation of the electric vehicles.

[0005] A primary object of the present disclosure is to enable smooth operation of an electric vehicle that transports cargo at least within a facility, while enabling power to be supplied from a power storage device of the electric vehicle to the facility's power system. [Means for solving the problem]

[0006] The power management system disclosed herein manages the exchange of power between power storage devices of multiple electric vehicles that transport at least cargo within a facility and charging / discharging devices connected to the facility's power grid. The power management system includes a vehicle management device. When at least one electric vehicle requests power supply to the power grid, the vehicle management device selects an electric vehicle that has excess capacity for discharging from its power storage device based on the SOC of the power storage device of each electric vehicle and the weight of the cargo on each electric vehicle. The vehicle management device then instructs the selected electric vehicle to discharge power from its power storage device to the power grid.

[0007] The electric vehicle of the present disclosure transports cargo at least within a facility. The electric vehicle includes a power storage device and a control device. The power storage device exchanges power with a charging / discharging device connected to the facility's power grid. When a power storage device requests power supply to the power grid, the control device determines whether there is a surplus capacity for discharging from the power storage device based on the SOC of the power storage device and the weight of the cargo. If there is a surplus capacity for discharging from the power storage device, the control device lowers the lower limit SOC of the power storage device compared to when there is no surplus capacity for discharging from the power storage device.

[0008] According to the power management system and electric vehicle of the present disclosure, it is possible to smoothly operate the electric vehicle that transports cargo at least within the facility, while supplying power from the power storage device of the electric vehicle to the facility's power system. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram showing a facility to which a power management system according to the present disclosure is applied; [Figure 2] FIG. 2 is a schematic diagram showing the configuration of an electric vehicle used in the facility of FIG. [Figure 3] 10 is a flowchart illustrating a routine executed by a vehicle management device of the power management system of the present disclosure. [Figure 4] 3 is a flowchart illustrating an example of a routine executed in the electric vehicle of the present disclosure. [Figure 5] 10 is a flowchart showing another example of a routine executed in the electric vehicle of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, embodiments of the present disclosure will be described with reference to the drawings.

[0011] FIG. 1 is a schematic configuration diagram showing a facility 1 to which a power management system 10 according to the present disclosure is applied. The facility 1 shown in the figure is an airport. In addition to various facilities (not shown) related to aircraft operations and the like, the facility 1 includes a power system 2 that supplies AC power to each facility, and a charging / discharging area 3 for a plurality of electric vehicles 20 that transport cargo C within the facility 1. The power system 2 is linked to the power transmission equipment of an electric power company and a plurality of power supply devices such as renewable energy power generation devices (such as solar power generation devices and wind power generation devices) and cogeneration systems installed within the facility 1. A plurality of charging / discharging devices 4, a plurality of charging / discharging devices 5, and a plurality of charging / discharging devices 6 are installed in the charging / discharging area 3.

[0012] The charging / discharging device 4 is a DC rapid charging / discharging device. The charging / discharging device 4 converts AC power from the power system 2 into DC power and supplies it to the battery (power storage device) 21 of the electric vehicle 20, and can also convert DC power from the battery 21 into AC power and supply it to the power system 2. The charging / discharging device 5 is an AC charging / discharging device. The charging / discharging device 5 can transform AC power from the power system 2 and supply it to the battery 21 of the electric vehicle 20, and can also transform AC power from the battery 21 and supply it to the power system 2. The charging / discharging device 6 is a non-contact charging / discharging device. The charging / discharging device 6 can also transform AC power from the power system 2 and supply it to the battery 21 of the electric vehicle 20, and can also transform AC power from the battery 21 and supply it to the power system 2. That is, the power system 2 can be linked to the battery 21 of the electric vehicle 20 as a power supply device via the charging / discharging devices 4, 5, and 6. The charging / discharging area 3 may be provided with at least one charging / discharging device 4 and at least one charging / discharging device 5. The charging / discharging device 6 may be omitted from the charging / discharging area 3.

[0013] The electric vehicle 20 is a battery electric vehicle (BEV) or a plug-in hybrid vehicle (PHEV). The electric vehicle 20 includes trucks, vans, one-box cars, towing tractors, belt loaders, ramp buses, food loaders, sewage trucks, water tankers, trash trucks, fuel trucks, etc. The electric vehicle 20 may be one that travels outside the facility 1 as well as within the facility 1, and may be an autonomous vehicle. The cargo C of the electric vehicle 20 includes cargo that is loaded on a dolly towed by a towing tractor.

[0014] As shown in Fig. 2, the electric vehicle 20 includes a system main relay SMR, a power control unit (hereinafter referred to as "PCU") 22, and a motor generator MG in addition to a battery 21. The battery 21 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. A positive power line PL is connected to a positive terminal of the battery 21 via a positive relay of the system main relay SMR. A negative power line NL is connected to a negative terminal of the battery 21 via a negative relay of the system main relay SMR.

[0015] The PCU 22 is connected to the battery 21 via a positive power line PL, a negative power line NL, and a system main relay SMR. The PCU 22 includes an inverter (drive circuit) 22i that drives the motor generator MG, a boost converter 22c, and the like. The motor generator MG is a synchronous generator motor (three-phase AC motor). The rotor of the motor generator MG is connected to a drive shaft DS that is connected to the drive wheels DW via a power transmission mechanism that includes a reducer and a differential gear. The motor generator MG is driven by electric power from the PCU 22 (battery 21) and outputs drive torque (drive force) to the drive shaft DS. Furthermore, the motor generator MG outputs regenerative braking torque to the drive shaft DS when braking the electric vehicle 20.

[0016] As shown in FIG. 2 , electric vehicle 20 also includes a DC receptacle 24 into which a charge / discharge connector of charge / discharge device 4 is plugged, an AC receptacle 25 into which a charge / discharge connector of charge / discharge device 5 is plugged, and a non-contact power transmitting / receiving device 26. DC receptacle 24 is connected to a relay DCR. Relay DCR is connected to a positive power line PL and a negative power line NL between a system main relay SMR and PCU 22. When relay DCR and system main relay SMR are closed, DC receptacle 24 is connected to battery 21. AC receptacle 25 is connected to a charging / discharging device 27 including an AC / DC converter and a DC / DC converter. Charging / discharging device 27 is connected to a positive power line PL and a negative power line NL between the system main relay SMR and PCU 22 via a relay CHR. When relay CHR and system main relay SMR are closed, AC receptacle 25 is connected to battery 21 via charging / discharging device 27 .

[0017] The non-contact power transmitting and receiving device 26 includes an AC / DC converter and a DC / DC converter. The non-contact power transmitting and receiving device 26 is fixed to the underside of a floor panel of the electric vehicle 20 and connected to the relay NCR. The relay NCR is connected to the positive power line PL and the negative power line NL between the system main relay SMR and the PCU 22. When the relay NCR and the system main relay SMR are closed, the non-contact power transmitting and receiving device 26 is connected to the battery 21. The non-contact power transmitting and receiving device 26 can contactlessly receive AC power from the charging and discharging device 6 in the charging and discharging area 3 and can convert power from the battery 21 into AC power and transmit it to the charging and discharging device 6 contactlessly.

[0018] As shown in FIG. 2 , the electric vehicle 20 further includes an electronic control unit (hereinafter referred to as “ECU”) 200 that manages the battery 21, and an on-board communication device 201. The ECU 200 is a microcomputer including a CPU, ROM, RAM, etc. (not shown). The ECU 200 calculates the SOC of the battery 21 based on the terminal voltage, charge / discharge current, temperature, etc. of the battery 21. The ECU 200 also controls the non-contact power transmitting / receiving device 26 and the charge / discharge device 27, and controls the opening and closing of relays DCR, CHR, and NCR. The ECU 200 also calculates the weight of the load C based on detection values ​​of a suspension stroke sensor (not shown) of the electric vehicle 20, etc. The on-board communication device 201 exchanges various information with the ECU 200 and also exchanges various information with external devices via high-speed wireless data communication (packet communication).

[0019] The power management system 10 manages the exchange of power between batteries 21 of multiple electric vehicles 20 and charging / discharging devices 4, 5, or 6, each connected to a power grid 2 of a facility 1. As shown in FIG. 1 , the power management system 10 includes a facility management server (facility management device) 11 and a vehicle management server (vehicle management device) 12. The facility management server 11 manages the supply and demand of power in the facility 1. The vehicle management server 12 exchanges information with the facility management server 11, and manages all electric vehicles 20 used in the facility 1 and the charging / discharging area 3.

[0020] The facility management server 11 includes a computer having a CPU, ROM, RAM, input / output devices, etc., and a storage device for storing various information. The facility management server 11 includes a power monitoring unit 13 and a power usage plan creation unit 15, which are configured by the cooperation of hardware such as the CPU, ROM, and RAM and pre-installed programs. The power monitoring unit 13 acquires information such as the voltage and frequency of the power grid 2 and monitors the power fluctuations in the power grid 2 based on the acquired information. The power monitoring unit 13 also acquires information on the power usage status of each piece of equipment in the facility 1 (including the charging / discharging area 3). The power usage plan creation unit 15 creates a power usage plan for the facility 1 based on the information acquired by the power monitoring unit 13 at predetermined intervals (e.g., every 1-2 hours) and transmits the created power usage plan to each piece of equipment in the facility 1. The power usage plan includes the predicted amount of power usage, predicted surplus power, predicted power shortage, and allowable power usage for each piece of equipment within the predetermined time period.

[0021] The vehicle management server 12 includes a computer having a CPU, ROM, RAM, input / output devices, etc., a storage device that stores various information, and a communication device 14 for communicating with the onboard communication device 201 of the electric vehicle 20. The vehicle management server 12 exchanges information with the charging / discharging devices 4, 5, and 6 in the charging / discharging area 3. Furthermore, the vehicle management server 12 includes a vehicle operation plan creation unit 16 and a charge / discharge plan creation unit 18, which are configured by the cooperation of hardware such as the CPU, ROM, and RAM and pre-installed programs. The vehicle operation plan creation unit 16 creates a vehicle operation plan for all electric vehicles 20 used in the facility 1 at predetermined time intervals (e.g., every 1-2 hours). The charge / discharge plan creation unit 18 creates a charge / discharge plan for the batteries 21 of all electric vehicles 20 used in the facility 1 at predetermined time intervals (e.g., every 1-2 hours). The charge / discharge plan specifies, for each electric vehicle 20, whether charging or discharging of the battery 21 is necessary, the target SOC of the battery 21, the charge / discharge device 4, 5 or 6 in the charge / discharge area 3 to be connected, and the like.

[0022] Next, the procedure for creating a vehicle operation plan and a charge / discharge plan by the vehicle management server 12 will be described with reference to Fig. 3. Fig. 3 is a flowchart showing a routine executed by the vehicle management server 12 in response to receiving a power usage plan from the facility management server 11 (power usage plan creation unit 15).

[0023] 3, the vehicle management server 12 acquires the power usage plan from the facility management server 11 (step S100). Next, based on the information from the charging / discharging area 3, the vehicle management server 12 extracts electric vehicles 20 that are not connected to the charging / discharging device 4, 5, or 6 in the charging / discharging area 3 (step S110). Furthermore, the vehicle management server 12 acquires the position information and the SOC of the battery 21 of the electric vehicles 20 extracted in step S110 (step S120). In step S120, the vehicle management server 12 requests the electric vehicles 20 that are not connected to the charging / discharging device 4, 5, or 6 to transmit the position information and the SOC of the battery 21. In response to the request from the vehicle management server 12, the ECU 200 of the electric vehicle 20 transmits the vehicle position information and the SOC of the battery 21 acquired by GPS to the vehicle management server 12 via the on-board communication device 201.

[0024] After the processing of step S120, the vehicle operation plan creation unit 16 of the vehicle management server 12 updates the vehicle operation plan based on the position information of each electric vehicle 20, the SOC of the battery 21 of each electric vehicle 20, the planned driving distance of each electric vehicle 20 until the next update timing of the vehicle operation plan (the next execution timing of the routine in FIG. 3), etc. (step S130). Note that the position information and the SOC of the battery 21 of the electric vehicle 20 connected to the charging / discharging device 4, etc. are transmitted from the charging / discharging device 4, etc. to the vehicle management server 12. In addition, the vehicle management server 12 acquires the weight of the cargo C of each electric vehicle 20 (step S140). The weight of the cargo C of the electric vehicle 20 parked in the charging / discharging area 3 is acquired based on the detection value of a vehicle weight scale (not shown) installed in the parking space of the charging / discharging area 3. The weight of the cargo C of the electric vehicle 20 that is not connected to the charging / discharging device 4, 5 or 6 in the charging / discharging area 3 is calculated by the ECU 200 of the electric vehicle 20 and transmitted from the in-vehicle communication device 201 to the vehicle management server 12.

[0025] Next, the vehicle management server 12 determines whether the power supply in the power system 2 is tight based on the power usage plan from the facility management server 11 (step S150). If the power supply in the power system 2 is not tight (step S150: NO), the charge / discharge plan creation unit 18 of the vehicle management server 12 selects an electric vehicle 20 whose battery 21 should be charged based on the amount of power usage allowed for the charge / discharge area 3 in the power usage plan and the SOC of the battery 21 of each electric vehicle 20 (step S160). Furthermore, the charge / discharge plan creation unit 18 creates a charge / discharge plan (here, a charging plan) for the electric vehicle 20 based on the selection result of step S160 and the weight of the cargo C of each electric vehicle 20 acquired in step S140 (step S170).

[0026] In step S170, the charge / discharge plan creation unit 18 sets the target SOC of the battery 21 of an electric vehicle 20 whose weight of cargo C is equal to or greater than a predetermined, relatively large first weight, to be higher than that of the battery 21 of an electric vehicle 20 whose weight of cargo C is less than the first weight. As a result, when the batteries 21 of multiple electric vehicles 20 are charged with power from the power grid 2 according to the charge / discharge plan, the target SOC of the battery 21 of an electric vehicle 20 whose weight of cargo C is large will be higher than that of the battery 21 of an electric vehicle 20 whose weight of cargo C is small. Then, the vehicle management server 12 transmits a charge command based on the charge / discharge plan to an electric vehicle 20 whose battery 21 should be charged and which is not connected to the charge / discharge device 4, 5, or 6 in the charge / discharge area 3 (step S180), and ends the routine of FIG. 3.

[0027] The charging command from the vehicle management server 12 includes the target SOC of the battery 21 and the charging / discharging device 4, 5, or 6 in the charging / discharging area 3 to which the electric vehicle 20 is to be connected. In response to receiving the charging command, the electric vehicle 20 whose battery 21 is to be charged is driven manually or automatically to a designated parking space in the charging / discharging area 3. The vehicle management server 12 also transmits the charging / discharging plan created in step S170 to the charging / discharging devices 4, 5, and 6 in the charging / discharging area 3. The charging / discharging devices 4, 5, and 6 charge the battery 21 of the corresponding electric vehicle 20 with power from the power grid 2 in accordance with the charging / discharging plan from the vehicle management server 12.

[0028] On the other hand, if the power supply in the power system 2 is tight and at least one electric vehicle 20 is requesting power supply to the power system 2 (step S150: YES), the charge / discharge plan creation unit 18 of the vehicle management server 12 selects an electric vehicle 20 that has a margin for discharging power from the battery 21 based on the SOC of the battery 21 of each electric vehicle 20 and the weight of the cargo C of each electric vehicle 20 acquired in step S140 (step S165). In step S165, the charge / discharge plan creation unit 18 selects, for example, an electric vehicle 20 whose battery 21 SOC is equal to or greater than a predetermined, relatively large, discharge allowable threshold and whose cargo C weight is less than a predetermined, relatively small, second weight.

[0029] Furthermore, the charge / discharge plan creation unit 18 creates a charge / discharge plan (here, a discharge plan) for the electric vehicles 20 based on the selection result of step S165 (step S175). In step S175, the charge / discharge plan creation unit 18 sets a predetermined value S0 lower than the predetermined lower limit SOC value S1 of the battery 21 of each electric vehicle 20 as the target SOC of the electric vehicles 20 that have capacity to discharge from their batteries 21 selected in step S165. Then, the vehicle management server 12 transmits a discharge command based on the charge / discharge plan to the electric vehicles 20 that are not connected to the charge / discharge device 4, 5, or 6 in the charge / discharge area 3 and have capacity to discharge from their batteries 21 (step S185), and ends the routine of FIG. 3.

[0030] The discharge command from the vehicle management server 12 includes the target SOC of the battery 21, the charging / discharging devices 4, 5, or 6 in the charging / discharging area 3 to which the electric vehicle 20 is to be connected, and the like. In the present embodiment, when the ECU 200 of the electric vehicle 20 receives a command signal from the vehicle management server 12 via the in-vehicle communication device 201, it executes the routine shown in FIG. 4. The ECU 200 acquires the content of the command signal from the vehicle management server 12 (step S200), and determines whether the command signal is a discharge command (step S210). When the command signal from the vehicle management server 12 is a charging command (step S210: NO), the ECU 200 sets (maintains) the above value S1 to the lower limit SOC of the battery 21 (step S220), and ends the routine of FIG. 4. When the command signal from the vehicle management server 12 is a discharge command (step S210: YES), the ECU 200 sets (changes) the above value S0 (<S1) that matches the target SOC to the lower limit SOC of the battery 21 (step S225), and ends the routine of FIG. 4. That is, the vehicle management server 12 lowers the lower limit SOC of the electric vehicle 20 having sufficient capacity for discharging from the battery 21 compared to the electric vehicle 20 having no sufficient capacity for discharging from the battery 21.

[0031] The electric vehicle 20 for which the battery 21 is to be discharged is caused to travel to a designated parking space in the charging / discharging area 3 by a driver or autonomous driving in response to the reception of the discharge command. Further, the vehicle management server 12 transmits the charging / discharging plan created in step S175 to the charging / discharging devices 4, 5, and 6 in the charging / discharging area 3. The charging / discharging devices 4, 5, and 6 discharge the battery 21 of the corresponding electric vehicle 20 according to the charging / discharging plan from the vehicle management server 12, and supply the power from the battery 21 to the power grid 2. When discharging from the battery 21 to the power grid 2, the operation of the charging / discharging device 4, 5, or 6 may be stopped when the SOC of the battery 21 reaches the target SOC (=S0). Also, when the SOC of the battery 21 reaches the target SOC (=S0), the relays DCR, CHR, or NCR may be opened by the ECU 200 of the electric vehicle 20.

[0032] As described above, the power management system 10 includes a vehicle management server 12 that manages the exchange of power between the batteries 21 of multiple electric vehicles 20 that transport at least a load C within the facility 1 and the charging / discharging devices 4, 5, and 6 connected to the power grid 2 of the facility 1. When at least one electric vehicle 20 requests power supply to the power grid 2 (step S150: YES), the vehicle management server 12 selects an electric vehicle 20 that has a margin for discharging power from its battery 21 based on the SOC of the battery 21 of each electric vehicle 20 and the weight of the load C on each electric vehicle 20 (step S165). That is, the vehicle management server 12 appropriately selects an electric vehicle 20 that can supply power to the power grid 2 of the facility 1, taking into consideration the weight of the load C in addition to the SOC of the battery 21. This prevents power from being supplied to the power grid 2 from an electric vehicle 20 that does not have a margin for discharging power from its battery 21, thereby preventing a shortage of SOC in the battery 21 of that electric vehicle 20. Furthermore, the vehicle management server 12 instructs the selected electric vehicle 20 to discharge power from its battery 21 to the power grid 2 (step S185). This enables an electric vehicle 20 with excess power for discharging from its battery 21 to be connected to the charge / discharge device 4, 5, or 6. As a result, the power management system 10 makes it possible to smoothly operate a plurality of electric vehicles 20 transporting cargo C while supplying power from the batteries 21 of the electric vehicles 20 to the power grid 2 of the facility 1.

[0033] Furthermore, the vehicle management server 12 lowers the lower limit SOC of the electric vehicle 20 that has a surplus capacity for discharging from the battery 21 compared to the electric vehicle 20 that has no surplus capacity for discharging from the battery 21 (steps S175, S185). This enables the electric vehicle 20 that has a surplus capacity for discharging from the battery 21 to supply more power to the power grid 2.

[0034] Furthermore, the power management system 10 includes a facility management server 11 that monitors the power supply and demand state of the power system 2 and creates a power usage plan for the facility 1. The vehicle management server 12 creates an operation plan for the multiple electric vehicles 20 based on the power usage plan created by the facility management server 11 (step S130), and determines whether or not a power supply from at least one electric vehicle 20 to the power system 2 is requested based on the power usage plan (step S150). This achieves a good balance between power supply and demand in the facility 1.

[0035] Furthermore, when the batteries 21 of the multiple electric vehicles 20 are charged with power from the power grid 2 (step S150: NO), the vehicle management server 12 sets the target SOC of the batteries 21 of the electric vehicles 20 carrying a heavy load C higher than that of the batteries 21 of the electric vehicles 20 carrying a light load C (step S170). This allows the batteries 21 of the multiple electric vehicles 20 to be appropriately charged, enabling the multiple electric vehicles 20 to be operated smoothly.

[0036] The power management system 10 may be applied to facilities other than airports. For example, the power management system 10 may be applied to factories, logistics facilities such as distribution centers, large-scale commercial facilities, and the like.

[0037] Alternatively, the ECU 200 of the electric vehicle 20 may determine whether there is sufficient power to discharge the battery 21 of the electric vehicle 20, instead of the vehicle management server 12. FIG. 5 is a flowchart illustrating a routine that may be executed by the ECU 200 in response to the receipt by the in-vehicle communication device 201 of a command signal from the vehicle management server 12. When the in-vehicle communication device 201 receives the command signal from the vehicle management server 12, the ECU 200 acquires the content of the command signal from the vehicle management server 12 (step S300) and determines whether the command signal is a discharge command (step S310). If the command signal from the vehicle management server 12 is a charge command (step S310: NO), the ECU 200 sets (maintains) the value S1 as the lower limit SOC of the battery 21 (step S315) and ends the routine of FIG. 5.

[0038] If the command signal from the vehicle management server 12 is a discharge command requesting discharge from the battery 21 to the power grid 2 (step S310: YES), the ECU 200 acquires the separately calculated SOC of the battery 21 and the weight of the cargo C (step S320) and determines whether there is a margin for discharge from the battery 21 (step S330). In step S330, the ECU 200 determines, for example, whether the SOC of the battery 21 is equal to or greater than a predetermined, relatively large, discharge allowance threshold and the weight of the cargo C is less than a predetermined, relatively small, second weight. If the SOC of the battery 21 is less than the discharge allowance threshold or the weight of the cargo C is equal to or greater than the second weight and there is no margin for discharge from the battery 21 (step S340: NO), the ECU 200 sets (maintains) the value S1 as the lower limit SOC of the battery 21 (step S315) and ends the routine of FIG. 5. On the other hand, if the SOC of the battery 21 is equal to or greater than the discharge tolerance threshold, the weight of the cargo C is less than the second weight, and there is remaining capacity for discharge from the battery 21 (step S340: YES), the ECU 200 sets the above value S0, which is lower than the value S1, as the lower limit SOC of the battery 21 (step S350), and terminates the routine of Figure 5.

[0039] 5 takes into consideration the weight of the load C as well as the SOC of the battery 21 to appropriately determine whether the battery 21 can supply power to the power grid 2 of the facility 1. When the battery 21 has a margin for discharge (YES in step S340), the ECU 200 lowers the lower limit SOC of the battery 21 (step S350) compared to when the battery 21 does not have a margin for discharge (NO in step S340). This enables the battery 21 to supply more power to the power grid 2 when the battery 21 has a margin for discharge. Furthermore, when the battery 21 does not have a margin for discharge, the ECU 200 prevents the battery 21 from supplying more power than necessary to the power grid 2, thereby preventing the SOC of the battery 21 from becoming insufficient. As a result, it becomes possible to supply power from the battery 21 of the electric vehicle 20 to the power grid 2 of the facility 1 while smoothly operating the electric vehicle 20 transporting the load C.

[0040] As described above, the power management system (10) of the present disclosure manages the exchange of power between the power storage devices (21) of a plurality of electric vehicles (20) that each transport a load (C) at least within a facility (1) and the charging / discharging devices (4, 5, 6) connected to the power grid (2) of the facility (1). The power management system (10) includes a vehicle management device (12). When a power supply from at least one electric vehicle (20) to the power grid (2) is requested (S150: YES), the vehicle management device (12) selects an electric vehicle (20) that has a surplus capacity for discharging from the power storage device (21) based on the SOC of the power storage device (21) of each electric vehicle (20) and the weight of the load (C) of each electric vehicle (20) (S165). That is, the vehicle management device (12) appropriately selects an electric vehicle (20) capable of supplying power to the power grid (2) of the facility (1) by taking into consideration the weight of the cargo (C) as well as the SOC of the power storage device (21). This prevents an electric vehicle (20) that does not have sufficient capacity to discharge from the power storage device (21) from supplying power to the power grid (2), thereby preventing the SOC of the power storage device (21) of the electric vehicle (20) from becoming insufficient. Furthermore, the vehicle management device (12) instructs the selected electric vehicle (20) to discharge from the power storage device (21) to the power grid (S185). This allows an electric vehicle (20) that has sufficient capacity to discharge from the power storage device (21) to be connected to the charging / discharging devices (4, 5, 6). As a result, according to the power management system (1) of the present disclosure, it is possible to smoothly operate a plurality of electric vehicles (20) that transport cargo (C) at least within the facility (1), while supplying power from the storage devices (21) of the electric vehicles (20) to the power system (2) of the facility (1).

[0041] The vehicle management device (12) may lower the lower limit SOC of the electric vehicle (20) having a surplus capacity for discharging from the power storage device (21) compared to the electric vehicle (20) having no surplus capacity for discharging from the power storage device (21) (S175, S185). This enables the electric vehicle (20) having a surplus capacity for discharging from the power storage device (21) to supply more power to the power grid (2).

[0042] The power management system 10 may include a facility management device 11 that monitors the power supply and demand state of the power grid 2 and creates a power usage plan for the facility. The vehicle management device 12 may create an operation plan for the plurality of electric vehicles 20 (S130) based on the power usage plan created by the facility management device 11, and may determine whether or not a power supply from at least one electric vehicle 20 to the power grid 2 is requested (S150) based on the power usage plan. This power management system 10 can achieve a good balance between power supply and demand in the facility 1.

[0043] When the power storage devices 21 of the plurality of electric vehicles 20 are charged with power from the power grid 2 (S150: NO), the vehicle management device 12 may set the target SOC of the power storage devices 21 of the electric vehicles 20 having a heavy load C higher than that of the power storage devices 21 of the electric vehicles 20 having a light load C (S175). This allows the power storage devices 21 of the plurality of electric vehicles 20 to be appropriately charged, thereby enabling smooth operation of the plurality of electric vehicles 20.

[0044] The electric vehicle (20) of the present disclosure transports a load (C) at least within a facility (1). The electric vehicle (20) includes a power storage device (21) and a control device (200). The power storage device (21) exchanges electric power with charging / discharging devices (4, 5, 6) connected to a power grid (2) of the facility (1). When a request for power supply from the power storage device (21) to the power grid (2) is received (S310: YES), the control device (200) determines whether there is a surplus capacity for discharging from the power storage device (21) based on the SOC of the power storage device (21) and the weight of the load (C) (S330, S340). That is, the control device (200) appropriately determines whether power can be supplied from the power storage device (21) to the power grid (2) of the facility (1) by taking into account the weight of the load (C) as well as the SOC of the power storage device (21). Furthermore, when there is a surplus capacity for discharge from the power storage device (21) (YES at S340), the control device (200) lowers (S350) the lower limit SOC of the power storage device (21) compared to when there is no surplus capacity for discharge from the power storage device (21) (NO at S340). This enables more power to be supplied to the power grid (2) when there is a surplus capacity for discharge from the power storage device (21). Furthermore, when there is no surplus capacity for discharge from the power storage device (21), the control device (200) prevents the power storage device (21) from supplying more power than necessary to the power grid (2), thereby preventing the SOC of the power storage device (21) from becoming insufficient. As a result, it becomes possible to supply power from the power storage device (21) of the electric vehicle (20) to the power grid (2) of the facility (1) while smoothly operating the electric vehicle (20) that transports the load (C) at least within the facility (1).

[0045] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment is merely a specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0046] The invention of the present disclosure can be used in facilities where loads are transported by multiple electric vehicles and in the electric vehicle manufacturing industry. [Explanation of symbols]

[0047] 1 facility, 2 power system, 3 charging area, 4, 5, 6 charging / discharging device, 10 power management system, 11 facility management server (facility management device), 13 power monitoring unit, 15 power usage plan creation unit, 12 vehicle management server (vehicle management device), 14 communication device, 16 vehicle operation plan creation unit, 18 charging / discharging plan creation unit, 20 electric vehicle, 21 battery, 200 electronic control unit (ECU), MG motor generator.

Claims

1. An electric power management system that manages exchange of electric power between power storage devices of a plurality of electric vehicles that transport cargo at least within a facility and charging / discharging devices connected to a power grid of the facility, a vehicle management device that, when a request for power supply from at least one of the electric vehicles to the power grid is received, selects an electric vehicle that has excess capacity for discharging from the power storage device based on an SOC of the power storage device of each of the electric vehicles and a weight of the cargo of each of the electric vehicles, and instructs the selected electric vehicle to discharge from the power storage device to the power grid.

2. 2. The power management system according to claim 1, The vehicle management device is an electric power management system that lowers the lower limit SOC of the electric vehicle that has a surplus capacity for discharging from the power storage device compared to the electric vehicle that does not have a surplus capacity for discharging from the power storage device.

3. 3. The power management system according to claim 1, a facility management device that monitors the power supply and demand state of the power grid and creates a power usage plan for the facility; The vehicle management device creates an operation plan for the plurality of electric vehicles based on the power usage plan created by the facility management device, and determines, based on the power usage plan, whether or not a power supply from at least one of the electric vehicles to the power grid is requested.

4. 3. The power management system according to claim 1, The vehicle management device is a power management system that, when the storage devices of the multiple electric vehicles are charged with power from the power grid, sets a target SOC of the storage devices of the electric vehicles with a heavy load to a higher value than that of the storage devices of the electric vehicles with a lighter load.

5. An electric vehicle that transports cargo at least within a facility, a power storage device that exchanges power with a charging / discharging device connected to a power grid of the facility; a control device that, when a request for power supply from the power storage device to the power grid is made, determines whether or not there is a surplus capacity for discharge from the power storage device based on an SOC of the power storage device and a weight of the cargo, and, when there is a surplus capacity for discharge from the power storage device, lowers a lower limit SOC of the power storage device compared to when there is no surplus capacity for discharge from the power storage device; An electric vehicle equipped with:

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