Work machine, electric power control method, and electric power control system

Abstract

Provided is a work machine such as an electric excavator 100, the work machine comprising a vehicle body that includes a work device, an AC / DC converter 111 that is provided to the vehicle body and receives electric power from a system electric power supply 400, and a high-voltage power storage battery 112 that is provided to the vehicle body, and the work machine being operated by electric power that is received from the system electric power supply 400 by the AC / DC converter 111 and electric power from the high-voltage power storage battery 112, wherein the work machine comprises a first data transmission / reception unit 125 for receiving information outputted by a server 500 serving as an external device, and comprises a vehicle control device 120 for setting electric power to be received from the system electric power supply 400 on the basis of the information received by the first data transmission / reception unit 125. As a result, it is possible to provide a work machine, an electric power control method, and an electric power control system that make it possible to more appropriately distribute power acquired from the system electric power supply to the work machine, thereby both reducing load on the system electric power supply and improving work efficiency at a work site.

Description

Work machine, power control method and power control system

[0001] The present invention relates to a work machine, a power control method, and a power control system. In particular, the present invention relates to a work machine that operates using both power from a grid power supply and power from a battery, and to a power control method and a power control system that can be preferably applied to this work machine.

[0002] Recently, from an environmental perspective, electrically operated work machines have been increasingly used. As a method for supplying power to a work machine, there is a method in which power is supplied from both a grid power supply and a battery.

[0003] Patent Document 1 discloses an electric construction machine in which a controller calculates its own required power for driving multiple hydraulic actuators based on operation signals from multiple operating devices, calculates an allowable power as a power limit value that the electric motor can use based on its own required power, the required power of other electric construction machines received via a communication device, and the allowable power of the commercial power receiving equipment, and controls the power consumption of the electric motor so that it does not exceed the allowable power.

[0004] Japanese Patent Application Laid-Open No. 2020-39239

[0005] However, there is an upper limit to the amount of power that can be received from a grid power source. Meanwhile, the power required within a work site that shares the grid power source changes from time to time depending on the operating status and number of electrically powered products, such as work machines, operating at the work site. Furthermore, electric power companies may request a reduction in power usage depending on the power supply and demand situation of the entire power infrastructure. Therefore, it is necessary to achieve both a reduction in the load on the grid power source and improved work efficiency within the work site. In other words, it is necessary to more appropriately allocate power to work machines in accordance with the upper limit of the power that can be received from the grid power source and requests to reduce power usage. An object of the present invention is to provide a work machine, a power control method, and a power control system that can appropriately allocate power obtained from a grid power source to work machines, thereby achieving both a reduction in the load on the grid power source and improved work efficiency within the work site.

[0006] In order to solve the above problems, the present invention provides a work machine that includes a vehicle body including a work implement, power receiving means mounted on the vehicle body for receiving power from a power grid, and a battery mounted on the vehicle body, and that operates on power received from the power grid by the power receiving means and power from the battery, and that includes control means that sets the power to be received from the power grid based on information output by an external device mounted outside the work machine.In this case, it is possible to provide a work machine that can appropriately allocate power obtained from the power grid, thereby achieving both a reduction in the load on the power grid and improved work efficiency at the work site.

[0007] Here, the vehicle information system includes a data transceiver that transmits vehicle information to an external device and receives information output from the external device. The data transceiver transmits information on the power consumed by the vehicle to the external device as vehicle information. The external device receives new power information calculated from the power consumed by the vehicle over a predetermined period of time prior to the present based on the information on the power consumed by the vehicle. The control means sets the power to be received from the grid power supply based on the new power information determined by the external device received by the data transceiver. In this case, the power to be received from the grid power supply can be set according to the power most recently used by the vehicle itself. Furthermore, the predetermined period can be set to exclude periods during which the vehicle itself is stopped. In this case, the power most recently used by the vehicle itself can be calculated more accurately.

[0008] The present invention also provides a power control method in which a processor executes a program stored in memory to set the power received from a power grid based on a signal output from an external device for a work machine that operates on power from a power grid and power from a battery. In this case, it is possible to provide a power control method that can be preferably applied to a work machine that can achieve both a reduction in the load on the power grid and improved work efficiency at the work site.

[0009] Furthermore, the present invention provides a power control system comprising a plurality of work machines that operate on power from a grid power supply and power from a battery, and a management device that determines the power to be allocated from the grid power supply to each of the work machines based on the total power consumption of the plurality of work machines when they are operating, and the work machines are equipped with a control device that sets the power to be received from the grid power supply to the power determined by the management device.In this case, it is possible to provide a power control system that can be preferably applied to work machines that can achieve both a reduction in the load on the grid power supply and work efficiency at the work site.

[0010] According to the present invention, it is possible to provide a work machine, a power control method, and a power control system that can appropriately allocate power obtained from a power grid to a work machine, thereby achieving both a reduction in the load on the power grid and improved work efficiency at the work site.

[0011] 1 is a block diagram showing the overall configuration of a work site to which this embodiment is applied. FIG. 2 is a diagram showing a power control system of this embodiment. FIG. 3 is a flowchart showing a case where an operator sets the power to be received from the grid power supply while the electric shovel is in operation. FIG. 4 is a sequence diagram showing data exchange between a vehicle control device, a control device, and a database. FIG. 5 is a flowchart showing a case where a server calculates and sets the power to be received from the grid power supply while the electric shovel is in operation. FIG. 6 is a sequence diagram showing data exchange between a power plant, a vehicle control device, a control device, and a database. FIG. 7 is a flowchart showing a case where a server calculates and sets the power to be received from the grid power supply while the electric shovel is in operation. FIG. 8 is a sequence diagram showing data exchange between a power plant, a vehicle control device, a control device, and a database. (a) to (b) are diagrams explaining the most recent predetermined time period. (a) to (e) are diagrams showing transitions in the power state (mode) of an electric shovel. (a) is a diagram explaining a case where the power received from the grid power supply is changed. (b) to (d) are diagrams showing changes in peak power when the power source is changed. FIG. 9 is a diagram showing a specific example of a case where power received from the grid power supply is allocated to multiple electric shovels.

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0013] <Explanation of Overall Configuration of Work Site> FIG. 1 is a block diagram showing the overall configuration of a work site to which this embodiment is applied. Multiple work machines operate at the work site. The work site shown in the figure is a construction site. The illustration shows a case where an electric shovel 100 operates as a work machine at the construction site. Note that the work machine operating at the construction site is not limited to the electric shovel 100, and can be construction machinery such as a wheel loader, bulldozer, or crane truck. The work machine operating at the construction site may also be a truck 190 for transporting gravel or the like. Note that the work site is not limited to a construction site. For example, it can also be an agricultural work site where agricultural machinery operates as work machines. In this case, the agricultural machinery can be a felling machine, a timber processing machine, a tractor, a forestry work vehicle, a logging machine, or the like. Note that FIG. 1 shows a case where operation information of various work machines is collected in a server 500 via wireless communication or the like, and information is managed for operation, inspection, and maintenance.

[0014] The electric shovel 100 shown in the figure is an example of a work machine that operates using power from a grid power supply and power from a battery. The electric shovel 100 can also be said to be an example of an electric construction machine. A power cable 200 that supplies power to the electric shovel 100 is connected to the electric shovel 100. The power cable 200 is, for example, a high-voltage cable that is capable of transmitting three-phase alternating current. Both ends of the power cable 200 are connected to the electric shovel 100 and a reel-type cable container 300, and power is supplied to the electric shovel 100 via the reel-type cable container 300. The reel-type cable container 300 has the power cable 200 wound around a cable reel (not shown) housed within the container, and the power cable 200 is unwound from the cable reel toward the electric shovel 100.

[0015] The reel-type cable container 300 is supplied with power from a power grid 400. The power grid 400 is also called a commercial power source, and is power generated by a power plant 410 and supplied by a power company. In FIG. 1, power is supplied from two power grids 400.

[0016] The amount of power that can be used from the grid power supply 400 is limited by contract or other factors. The power limit is, for example, 88 VA. Therefore, even when multiple work machines are operating, the total power used cannot exceed this limit. A battery-powered work machine that operates solely on power from its battery needs to receive power from the grid power supply when charging. If multiple work machines are rapidly charging at the same time during a break, for example, this could result in an overload on the grid power supply or interference with rapid charging due to limitations on the available power. Furthermore, a cable-operated work machine that operates solely on power from the grid power supply could be disrupted in its operation or the normal operation of the grid power supply if the power demand based on output fluctuations of the work machine exceeds the available power. Therefore, this embodiment employs a battery-cable combined use work machine that is configured to receive power from the grid power supply while also using power from its own onboard battery. By individually setting an upper limit on the amount of power that can be used for each work machine depending on the conditions at the work site, it is possible to reduce the load on the grid power supply and respond to the power demands of the work machines.

[0017] However, the power required within a work site that shares a grid power supply changes from time to time depending on the operating status and number of electrically powered products, such as work machines, operating at the work site. Furthermore, there are cases where a request to reduce power usage is received from the power company depending on the power supply and demand situation of the entire power infrastructure. In such cases, a method of setting a fixed upper limit on the power received from the grid power supply for each work machine is not sufficient to achieve both a reduction in the load on the grid power supply and a response to the power requests of the work machines. Therefore, this embodiment aims to solve this problem by adopting a method of changing the power received by each work machine from the grid power supply, at least while the work machine is operating, depending on the operating status of the work machine.

[0018] <Explanation of the configuration of power control system 1> Fig. 2 is a diagram showing the power control system 1 of this embodiment. In the power control system 1 shown in Fig. 2, power is supplied from a system power supply 400 to an electric shovel 100 via a power cable 200. Note that, in the following explanation, for the sake of simplicity, a case will be described in which the work machine is the electric shovel 100, but it goes without saying that the invention can also be applied to cases in which the work machine is other than the electric shovel 100.

[0019] The electric shovel 100 includes a high-voltage circuit 110, a vehicle control device 120, a hydraulic circuit 130, an operation system 140, a power plant 410, a third data transmission / reception unit 411 of the power plant 410, and a server 500. The electric shovel 100 shown in the figure controls the high-voltage circuit 110 using power supplied from a power cable 200 via the vehicle control device 120 to drive a drive motor 118, which is a power source. High voltage circuit 110 is an example of a power receiving device that receives power from system power supply 400 and includes an AC / DC converter 111 that converts AC power supplied from power cable 200 into DC power, a high voltage storage battery 112 that is an example of a battery and stores power, a pre-charge relay 113 and a main relay 114 that control the ON / OFF of high voltage circuit 110, a resistor 115, a capacitor 116, an inverter 117 that converts DC power into AC power for driving drive motor 118, and drive motor 118.

[0020] When the high-voltage circuit 110 is turned on, the pre-charge relay 113 is first turned on. This causes charge to accumulate in the capacitor 116. Then, the main relay 114 is turned on. This prevents an inrush current from occurring when the high-voltage circuit 110 is turned on. It also prevents the terminals of the high-voltage circuit 110 from welding. The high-voltage circuit 110 supplies power to the drive motor 118 using power generated by the AC / DC converter 111 and the high-voltage storage battery 112. In other words, when the load on the drive motor 118 is small, the drive motor 118 is driven by power from the AC / DC converter 111. At this time, if there is a surplus of power supplied from the AC / DC converter 111, the high-voltage storage battery 112 is charged. On the other hand, when the load on the drive motor 118 increases and the power from the AC / DC converter 111 becomes insufficient, the shortfall in power is supplied from the high-voltage storage battery 112. The power supplied from the AC / DC converter 111 and the high-voltage storage battery 112 is converted into stable direct current by repeated charging and discharging by a capacitor 116. Then, an inverter 117 converts the direct current into alternating current at a desired frequency and voltage, and controls the rotation speed of a drive motor 118. This controls the amount of hydraulic pressure generated by a hydraulic pump 131, and operates the electric excavator 100.

[0021] The vehicle control device 120 sets the power to be received from the grid power supply 400 based on information output by a server 500, which is an external device provided outside the electric excavator 100. In other words, the vehicle control device 120 sets the power to be received from the grid power supply 400 to the power determined by the server 500. It can also be said that the vehicle control device 120 sets the power that the electric excavator 100 receives from the grid power supply 400 to the distributed power determined by the server 500. The AC / DC converter 111 then adjusts the power received from the grid power supply 400 (upper limit of received power). For example, the power received from the grid power supply 400 can be adjusted by adjusting the resistance value in a current limiting circuit of the AC / DC converter 111. The vehicle control device 120 includes a control and calculation function unit 121, a data recording unit (memory) 122, and a communication function unit 123. The control and calculation function unit 121 performs calculations to control the AC / DC converter 111, the high-voltage storage battery 112, and the inverter 117. The AC / DC converter 111, the high-voltage storage battery 112, and the inverter 117 are provided with control units (controllers) 111C, 112C, and 117C, respectively. The control units 111C, 112C, and 117C transmit data representing the states of the AC / DC converter 111, the high-voltage storage battery 112, and the inverter 117 to the control and calculation function unit 121. The control and calculation function unit 121 performs calculations based on the transmitted data and transmits control signals for controlling the AC / DC converter 111, the high-voltage storage battery 112, and the inverter 117 to the control units 111C, 112C, and 117C. When adjusting the power received from the grid power supply 400, the vehicle control device 120 transmits a command, and the control unit 111C of the AC / DC converter 111 receives the command. Then, the setting of the AC / DC converter 111 changes, thereby changing the power received from the grid power supply 400. The data recording unit (memory) 122 records program data used by the control and calculation function unit 121 to perform calculations. The communication function unit 123 is a communication interface used when transmitting control signals to the control units 111C, 112C, and 117C. In addition, a vehicle monitor 124 and a first data transmission / reception unit 125 are connected to the vehicle control device 120. The vehicle monitor 124 can display the status of the electric excavator 100.Furthermore, the vehicle monitor 124 is, for example, a touch panel, and the operator can input settings for the electric excavator 100 through the vehicle monitor 124. The first data transmitter / receiver 125 is an example of a first data communication device that receives information output by the server 500, which is an external device, and is a communication interface for communicating with the server 500, which is also an external device. The vehicle control device 120 sets the power to be received from the system power supply 400 based on the information received by the first data transmitter / receiver 125.

[0022] The hydraulic circuit 130 includes a hydraulic pump 131 that generates hydraulic pressure, a hydraulic oil tank 132 that stores hydraulic oil, a first directional control valve 133, and a second directional control valve 134. The hydraulic pump 131 is a variable displacement hydraulic pump driven by the drive motor 118. The hydraulic pump 131 draws hydraulic oil from the hydraulic oil tank 132 and supplies the hydraulic oil to the swing motor (not shown), boom cylinder 14, arm cylinder 16, and bucket cylinder 17 of the electric excavator 100 via the first directional control valve 133 and the second directional control valve 134, thereby operating the electric excavator 100. Note that hereinafter, when the boom cylinder 14, arm cylinder 16, and bucket cylinder 17 are not distinguished from one another, they may be simply referred to as the hydraulic cylinders 14, 16, and 17. The hydraulic cylinders 14, 16, and 17, as well as the boom, arm, and bucket (not shown), are examples of working devices.

[0023] The operation system 140 is provided in the driver's cab of the electric shovel 100, and is used by the operator when operating the electric shovel 100. The operation system 140 includes a work mode selection switch, a motor control dial (not shown) for setting the rotation speed of the drive motor 118, operation levers 141A, 141B, etc. The operation levers 141A, 141B correspond to the respective swing motors and hydraulic cylinders 14, 16, 17, and are, for example, electric levers that output an electric operation signal (lever signal Lv) corresponding to the amount of operation.

[0024] The server 500 is an example of a management device that determines multiple power distributions for distributing power received from the grid power supply 400 to each of the multiple electric excavators 100 based on the total power consumption when the work machines are operating. The server 500 is an external device and a server computer that manages the entire power control system 1. The server 500 can be, for example, a cloud server that operates on the cloud. The server 500 includes a second data transmitter / receiver 510, a control device 520, and a database 530. The second data transmitter / receiver 510 is a communication interface that exchanges data such as power with the electric excavators 100. In this case, the second data transmitter / receiver 510 communicates with a first data transmitter / receiver 125 that is connected to the vehicle control device 120 of the electric excavator 100. The control device 520 communicates with the multiple electric excavators 100 and obtains the power used by each electric excavator 100. The power that each electric excavator 100 receives from the grid power supply 400 is then determined. As will be described in detail later, as a first method for determining the power, worker B determines the power that each electric shovel 100 will receive from the grid power supply 400 based on the acquired power. Worker B is, for example, a manager of the power control system 1. As a second method for determining the power, the control device 520 determines the power that each electric shovel 100 will receive from the grid power supply 400 using a predetermined calculation method based on the acquired power. The determined power is sent to each electric shovel 100 via the second data transmission / reception unit 510. The database 530 stores a history of the acquired power.

[0025] The third data transmitter / receiver 411 of the power plant 410 transmits the allowable power value of the grid power supply 400 to the server 500, as will be described in detail later.

[0026] <Description of Processing Performed by Power Control System 1>

[0027] FIGS. 3 to 8 are flowcharts and sequence diagrams showing the processing performed by the power control system 1. Of these, FIG. 3 is a flowchart showing a case in which an operator B sets the power (hereinafter sometimes referred to as the "allowable power value") to be received from the grid power supply 400 while an electric shovel 100 (hereinafter sometimes referred to as the "vehicle body") is operating. In this case, the electric shovel 100, which is the vehicle body, includes a structure, a drive unit, and the like, and constitutes a work machine. First, operator B manually inputs the allowable power value (S301). For example, operator B monitors the power used by multiple electric shovels 100 (vehicle bodies) and sets the allowable power value depending on the work situation. For example, if a certain electric shovel 100 is performing work with a heavy load and using a lot of power, the allowable power value of that electric shovel 100 is increased. On the other hand, if a certain electric shovel 100 is performing work with a light load and using a small amount of power, the allowable power value of that electric shovel 100 is decreased. As a result, worker B allocates the power received from the grid power supply 400 in accordance with the status of the power used by each electric excavator 100 while observing the upper limit of the grid power supply 400 used. Next, the control device 520 recognizes the allowable power value (S302). Furthermore, the control device 520 transmits the allowable power value data to the second data transceiver 510 (S303). Then, the second data transceiver 510 wirelessly transmits the data to the first data transceiver 125 of the vehicle body (S304). In the electric excavator 100, the first data transceiver 125 of the vehicle body receives the allowable power value data from the second data transceiver 510 of the server 500 (S305). Next, the first data transceiver 125 of the vehicle body transmits the allowable power value data to the vehicle control device 120 (S306). Furthermore, the vehicle control device 120 transmits the allowable power value data to the AC / DC converter 111 (S307). Then, the AC / DC converter 111 performs power conversion in accordance with the allowable power value using its hardware (S308).

[0028] FIG. 4 is a sequence diagram showing data exchange between the vehicle control device 120, the control device 520, and the database 530. When worker B manually inputs the allowable power value, the vehicle control device 120 needs to understand the status of power usage by the multiple electric excavators 100. To this end, each vehicle control device 120 of the multiple electric excavators 100 transmits power consumption data to the control device 520 (S401). The control device 520 transmits the power consumption data to the database 530 and stores the data (S402). The control device 520 also acquires power consumption data for a predetermined period of time from the database 530 (S403). After viewing this data, worker B manually inputs the allowable power value (S404). This corresponds to S301 in FIG. 3. The control device 520 transmits the allowable power value to the vehicle control device 120 (S405). This corresponds to S304 in FIG. 3. The vehicle control device 120 changes the allowable power value (S406). This corresponds to S307 in FIG. 3.

[0029] 3 and 4 , the power to be received from the system power supply 400 is determined by a server 500, which is an external device, and the vehicle control device 120 obtains the power from the server 500 via communication. At this time, the power to be received from the system power supply 400 is determined by worker B, who is the manager, based on the power used by multiple work machines including the vehicle control device 120 itself (the vehicle body). At this time, worker B allocates power to the multiple electric excavators 100 within a range that does not exceed the upper limit of power that can be obtained from the system power supply 400 (in this case, the contracted power value). In this way, worker B can manually set the power that the electric excavators 100 receive from the system power supply 400 while the electric excavators 100 are operating.

[0030] 5 is a flowchart showing a case where the server 500 calculates and sets the amount of power to be received from the grid power supply 400 while the electric excavator 100 is operating. First, the control unit 117C of the inverter 117 transmits key ON / OFF information and power consumption data to the vehicle control device 120 (S501). Next, the first data transmission / reception unit 125 of the vehicle body wirelessly transmits this information to the second data transmission / reception unit 510 of the server 500 (S502).

[0031] In the server 500, the second data transmitter / receiver 510 transmits data to the control device 520 (S503). Next, the control device 520 transmits the data to the database 530 (S504). At this time, the database 530 receives the data from the control device 520 and stores the data (S505). Furthermore, the control device 520 calculates the allowable power value from the most recent power consumed by the electric excavator 100 for a predetermined period of time while the key was ON (S506). Then, the control device 520 transmits the allowable power value to the second data transmitter / receiver 510 (S507). The second data transmitter / receiver 510 wirelessly transmits the data to the first data transmitter / receiver 125 of the vehicle body (S508).

[0032] The first data transmitter / receiver 125 of the vehicle body receives the allowable power value data from the second data transmitter / receiver 510 of the server 500 (S509). The first data transmitter / receiver 125 of the vehicle body transmits the allowable power value data to the vehicle control device 120 (S510). The vehicle control device 120 then receives the allowable power value data (S511). Next, the vehicle control device 120 transmits the allowable power value data to the AC / DC converter 111 (S512). The hardware of the AC / DC converter 111 then performs power conversion in accordance with the allowable power value (S513).

[0033] FIG. 6 is a sequence diagram showing data exchange between the vehicle control device 120, the control device 520, and the database 530. First, power consumption data of the electric excavator 100 is transmitted to the control device 520 (S601). This corresponds to S502 in FIG. 5. The control device 520 transmits the power consumption data to the database 530 and stores the data (S602). This corresponds to S504 to S505 in FIG. 5. The control device 520 also acquires power consumption data for a predetermined period of time from the database 530 (S603), and calculates an allowable power value based on the acquired power consumption data (S604). This corresponds to S506 in FIG. 5. The control device 520 transmits the allowable power value to the vehicle control device 120 (S605). This corresponds to S508 in FIG. 5. The vehicle control device 120 changes the allowable power value (S606). This corresponds to S512 in FIG. 5.

[0034] 5 and 6 , the power to be received from the system power supply 400 is determined by the server 500, which is an external device, and the vehicle control device 120 obtains this power from the server 500 via communication. At this time, the server 500, which is an external device, calculates the power to be received from the system power supply 400 based on the power used by the electric excavator 100, which is the device itself, over a predetermined period going back from the present time. In this case, the server 500 calculates the power to be received from the system power supply 400 based on the power used by the electric excavator 100 while the device itself is operating, without taking into account the power of other electric excavators 100. In this way, the vehicle control device 120 can automatically set the power to be received from the system power supply 400 calculated by the server 500 while the electric excavator 100 is operating. In this case, the first data transmission / reception unit 125 transmits power consumption information, which is information about the power consumed by the vehicle body, to the server 500, and the server 500 receives information about new power that has been determined based on the power consumption information.The vehicle control device 120 then sets the power to be received from the system power supply 400 based on the new power information determined by the server 500 and received by the first data transmission / reception unit 125.

[0035] Figure 7 is also a flowchart showing a case in which the server 500 calculates and sets the amount of power to be received from the grid power supply 400 while the electric excavator 100 is operating. However, compared to the case in Figure 5, the method of calculating the power to be received from the grid power supply 400 is different. First, the control unit 117C of the inverter 117 of each of the multiple electric excavators 100 (vehicle bodies) transmits key ON / OFF information and power consumption data to the vehicle control device 120 (S701). Meanwhile, the control unit 112C of the high-voltage storage battery 112 of each of the multiple vehicle bodies transmits SOC (State Of Charge) data to the vehicle control device 120 (S702). Next, the first data transmission / reception unit 125 of the vehicle body wirelessly transmits this information to the second data transmission / reception unit 510 of the server 500 (S703).

[0036] In the server 500, the second data transmission / reception unit 510 transmits data to the control device 520 (S704). Meanwhile, the second data transmission / reception unit 510 in the server 500 receives the allowable power value of the grid power supply 400 within the construction site from the power plant 410 and transmits this value to the control device 520 (S705). Next, the control device 520 further transmits the data transmitted in S704 and S705 to the database 530 (S706). The database 530 receives the data from the control device 520 and stores the data (S707). Furthermore, the control device 520 calculates the distribution power required for each vehicle as the allowable power value for each vehicle from the most recent key ON / OFF, power consumption, SOC, and contracted power value of the grid power supply 400 (S708). Then, the control device 520 transmits the allowable power value to the second data transmission / reception unit 510 (S709). Furthermore, the second data transmitter / receiver 510 wirelessly transmits the distributed power required for each vehicle body to the first data transmitter / receiver 125 of each vehicle body (S710).

[0037] The first data transmitter / receiver 125 of each vehicle body receives the allowable power value data from the second data transmitter / receiver 510 of the server 500 (S711). The first data transmitter / receiver 125 of each vehicle body transmits the allowable power value data to the vehicle control device 120 (S712). The vehicle control device 120 then receives the allowable power value data (S713). Next, the vehicle control device 120 transmits the allowable power value data to the AC / DC converter 111 (S714). The hardware of the AC / DC converter 111 then performs power conversion in accordance with the allowable power value (S715).

[0038] 7 , the first data transmitter / receiver 125 transmits vehicle key ON / OFF information to the server 500, and receives new power information determined by the server 500 based on power consumption information (in this case, power consumption data) and information on power consumed while the vehicle is operating, which is determined from the key ON / OFF information. The first data transmitter / receiver 125 also transmits remaining battery capacity information (in this case, SOC data), which is information on the remaining capacity of the high-voltage storage battery 112, to the server 500, and receives new power information determined by the server 500 based on the power consumption information and the remaining battery capacity information.

[0039] On the other hand, the server 500 receives a plurality of pieces of power consumption information, which is information on the power consumed by the bodies of the plurality of electric shovels 100, and a contract power value, which is the power that can be obtained from the system power supply 400, determines the total power consumption based on the plurality of pieces of power consumption information, and determines the distribution power of the plurality of electric shovels 100 to be distributed to each of the electric shovels 100 based on the total power consumption, the plurality of pieces of power consumption information, and the contract power value, so that power is distributed to the electric shovels 100 in a range where the sum of the plurality of distribution powers does not exceed the contract power value, and transmits information on the determined plurality of distribution powers to each of the plurality of electric shovels 100.

[0040] FIG. 8 is a sequence diagram showing data exchange between the power plant 410, the vehicle control device 120, the control device 520, and the database 530. First, each vehicle control device 120 of the multiple electric excavators 100 transmits power consumption data and other data to the control device 520 (S801). This corresponds to S703 in FIG. 7. The power plant 410 transmits the contracted power value to the control device 520 (S802). This corresponds to S705 in FIG. 7. The control device 520 transmits the power consumption data and the contracted power value to the database 530 and stores the data (S803). This corresponds to S706 to S707 in FIG. 7. The control device 520 also acquires power consumption data of the multiple electric excavators 100 from the database 530 (S804), and calculates the allowable power value based on the acquired power consumption data (S805). This corresponds to S708 in FIG. 7. The control device 520 transmits the allowable power value data to the vehicle control device 120 (S806). This corresponds to S710 in Fig. 7. The vehicle control device 120 changes the allowable power value (S807). This corresponds to S714 in Fig. 7.

[0041] According to the method shown in FIGS. 7 and 8 , the amount of power received from the system power supply 400 is determined by the server 500, which is an external device, and the vehicle control device 120 obtains the amount of power received from the server 500 through communication. At this time, the power received from the system power supply 400 is calculated by the server 500, which is an external device, based on the power consumed by multiple electric excavators 100, including the electric excavator 100 itself. In this case, the server 500 takes into account the power consumption of not only the server 500 itself but also the other electric excavators 100. The server 500 then calculates the allocation of power to be received from the system power supply 400 based on the power consumption consumed by the multiple electric excavators 100 while the server 500 itself is operating. At this time, the server 500, which is an external device, allocates power to the multiple electric excavators 100 within a range that does not exceed the upper limit of power that can be obtained from the system power supply 400 (in this case, the contracted power value). In this way, the power to be received from the system power supply 400 calculated by the server 500 can be automatically set by the vehicle control device 120 while the electric excavator 100 is operating.

[0042] <Explanation of Most Recent Predetermined Time> In FIG. 5 , the control device 520 calculates the allowable power value from the power consumed by the electric shovel 100 during a predetermined time while the key was most recently ON. How this most recent predetermined time is determined will be described next. FIGS. 9( a) and 9(b) are diagrams illustrating the most recent predetermined time. In this embodiment, the most recent predetermined time is a predetermined period going back from the current time. FIG. 9(a) illustrates a case where this period can be continuously acquired. That is, during the predetermined period Δt going back from the current time indicated by "present," the electric shovel 100 has the key turned ON and is operating, and power consumption can be acquired. FIG. 9(b) illustrates a case where this period cannot be continuously acquired. That is, during the predetermined period Δt going back from the current time indicated by "present," there is a period when the key of the electric shovel 100 is turned OFF, and during this period, the electric shovel 100 is stopped, and power consumption cannot be acquired. In this case, the power consumption during the key-on period is obtained by going back further in time, and the total time is set to the predetermined period Δt. In FIG. 9B, the predetermined period is set so that the sum of the operating periods Δt1 and Δt2 is Δt (Δt1 + Δt2 = Δt). In other words, the predetermined period Δt is set excluding periods during which the device itself is stopped. Alternatively, if the predetermined period Δt includes a period during which the device is stopped, a predetermined initial value may be used.

[0043] <Explanation of Operating and Stopped> In this embodiment, whether the electric shovel 100 is operating or stopped is determined as follows. FIGS. 10( a) to 10(e) are diagrams showing the transition of the power state (mode) of the electric shovel 100. Here, the transition of the power state (mode) of the electric shovel 100 is shown when the electric shovel 100 is turned from key OFF to key ON and then back to key OFF. FIG. 10(a) shows the power state when the key of the electric shovel 100 is removed and the key is OFF. At this time, both the low-voltage circuit and the high-voltage circuit 110 (see FIG. 2) are off. FIG. 10(b) shows the power state when the key is inserted into the electric shovel 100 and the ACC (accessory) switch is turned on. At this time, the low-voltage circuit is turned on, but the high-voltage circuit 110 remains off. In this power state, the vehicle control device 120, vehicle monitor 124, and first data transmission / reception unit 125 of the electric excavator 100 can be operated, but the hydraulic circuit 130 cannot be operated, and the arm of the electric excavator 100 cannot be moved. FIG. 10( c) shows the power state when the main relay 114 of the high-voltage circuit 110 (see FIG. 2) is turned ON. At this time, both the low-voltage circuit and the high-voltage circuit 110 are turned ON. In this power state, the hydraulic circuit 130 of the electric excavator 100 can be operated, and the arm of the electric excavator 100 can be moved. FIG. 10( d) shows the power state when the main relay 114 of the high-voltage circuit 110 is turned OFF. The power state at this time is the same as FIG. 10( b), and the low-voltage circuit is ON but the high-voltage circuit 110 is OFF. FIG. 10( e) shows the power state when the key is removed from the electric excavator 100 and the key is turned OFF. The power state at this time is the same as that shown in FIG. 10A, and both the low voltage circuit and the high voltage circuit 110 are turned off.

[0044] In this embodiment, the electric shovel 100 being in operation refers to the state shown in Fig. 10(c). In other words, this refers to the state when both the low voltage circuit and the high voltage circuit 110 are turned on. On the other hand, in this embodiment, the electric shovel 100 being stopped refers to the states shown in Figs. 10(a) to 10(b) and 10(d) to 10(e). In other words, this refers to the state when the high voltage circuit 110 is turned off.

[0045] <Explanation of Effects> Next, the effects of this embodiment will be described. As described above, in this embodiment, the vehicle control device 120 changes the power received from the grid power supply 400. The timing of the change may be while the electric excavator 100 is operating or while it is stopped. Thus, even while the electric excavator 100 is stopped, the power received from the grid power supply 400 can be changed in response to a signal from the server 500. In other words, the change may be made at any time as long as the signal can be received on the electric excavator 100 side. When the change is made while the electric excavator 100 is stopped, such as at night or during a break when the remaining battery charge is less likely to fluctuate, optimal power distribution can be performed from outside the electric excavator 100 (without having to get on to drive the electric excavator 100), taking into consideration the remaining battery charge of the electric excavator 100 and the like, thereby enabling charge management within the work site.

[0046] FIG. 11( a) is a diagram illustrating a case where the power received from the grid power supply 400 is changed. In FIG. 11( a), the horizontal axis represents time, and the vertical axis represents the power consumption of the electric shovel 100. In the figure, dotted line L indicates the power received from the grid power supply 400. When the power consumption of the electric shovel 100 is equal to or less than dotted line L, the electric shovel 100 is operated using power from the grid power supply 400. At this time, the high-voltage storage battery 112, which is a battery, is charged with surplus power from the grid power supply 400. On the other hand, when the power consumption of the electric shovel 100 exceeds dotted line L, the shortage is replenished from the high-voltage storage battery 112, and the electric shovel 100 is operated using power from both the grid power supply 400 and the high-voltage storage battery 112. In this embodiment, the power received from the grid power supply 400 is changed using the method described above. This corresponds to moving the dotted line L up and down in FIG. 11( a). Furthermore, even if the power received by the electric shovel 100 changes or decreases while the electric shovel 100 is in operation, the shortfall is replenished from the high-voltage storage battery 112, so there is no impact on the operation of the electric shovel 100 or the operability of the operator.

[0047] This makes it possible to level out the peak power of the power received from the grid power supply 400. FIGS. 11(b) to 11(d) are diagrams showing changes in peak power when the power supply is changed. Of these, FIG. 11(b) is a diagram showing a case where the electric shovel 100 is operated using only the battery. In this case, when the electric shovel 100 is operated, the power received from the grid power supply 400 is zero. However, for example, it is necessary to charge the battery using power from the grid power supply 400 during a lunch break. In this case, charging must be performed in a short period of time, and therefore the peak power becomes high.

[0048] FIG. 11( c ) is a diagram showing a case where the electric shovel 100 is operated using only power from the grid power supply 400. Compared to the case of FIG. 11( a ), power is received from the grid power supply 400 for a longer period of time. Therefore, when considering a case where the same amount of power is received as in FIG. 11( a ), the power received from the grid power supply 400 is leveled and the peak power is reduced. However, since the power required to operate the electric shovel 100 increases or decreases depending on the type of work, the power received from the grid power supply 400 increases or decreases as shown in the figure. Therefore, the peak power does not decrease significantly, and power leveling is not sufficient. The amount of power corresponds to the area indicated in gray.

[0049] Fig. 11(d) shows the case of this embodiment, where the electric shovel 100 is operated using power from both the grid power supply 400 and the battery. In this case, the presence of the battery further equalizes the power received from the grid power supply 400, and the peak power becomes even smaller, compared to Fig. 11(c).

[0050] With regard to the power received from the grid power supply 400, if the peak power can be leveled, the power received from the grid power supply 400 can also be leveled. In this case, the power received from the grid power supply 400 can be more efficiently allocated in accordance with the power request required by each electric excavator 100. Furthermore, in this embodiment, the server 500 determines the power to be received from the grid power supply 400 by each electric excavator 100. In this case, the power to be received from the grid power supply 400 can be determined in accordance with the power request required by the plurality of electric excavators 100. Therefore, the power received from the grid power supply 400 can be more efficiently allocated. Therefore, even if the grid power supply 400 has an upper limit on the amount of power that can be used, such as contracted power, that power can be used more effectively. As a result, it is possible to achieve both a reduction in the load on the grid power supply 400 and a response to the power request of the electric excavator 100.

[0051] <Example> Fig. 7 illustrates an actual example of allocating power received from the grid power supply 400 to a plurality of electric excavators 100. Fig. 12 is a diagram showing a specific example of allocating power received from the grid power supply 400 to a plurality of electric excavators 100. Here, the amount of power allocated to each electric excavator 100 from the grid power supply 400 is determined based on the ratio between the average past power consumption of each electric excavator 100 and the remaining operating time calculated from the remaining SOC. Note that a case will be described in which power received from the grid power supply 400 is allocated to four electric excavators A to D. The average past power consumption of electric excavator A can be calculated using the following formula 1. Furthermore, the amount of power allocated to electric excavator A from the grid power supply 400 can be calculated using the following formula 2. Note that the same method can be used for allocating power to electric excavators B to D.

[0052]

[0053]

[0054] In equations 1 and 2, h Ａ ~h D is the remaining operating time [h] of the electric excavators A to D, h Ａｌｌ Is, h Ａ ~hＤ Total remaining operating time [h], SOC Ａ is the remaining battery power of the electric excavator A [kWh], P Ａ ａｖｅ is the average power consumption of electric shovel A [kW], P ｌｉｍ is the contracted power [kW] of the system power supply 400, P Ａ is the power [kW] allocated to the electric shovel A, and n is the number of electric shovels.

[0055] When the remaining operating time [h], SOC, and remaining battery capacity of the electric shovels A to D are as shown in the figure, the remaining operating time h of the electric shovels A to D can be calculated by the formula 1. Ａ ~h D are 3h, 2h, 2h, and 6h, respectively. From this, the remaining operating time h of electric excavators A to D is Ａ ~h D The ratio of A:B:C:D is 3h:2h:2h:6h, which results in a distribution ratio of 10:11:11:7. When the contracted power of the system power supply 400 is 88VA, the power that the electric excavators A to D receive from the system power supply 400 is A:B:C:D=22kW:25kW:25kW:16kW.

[0056] <Explanation of Power Control Method> The processing performed by the vehicle control device 120 in this embodiment described above is realized by cooperation between software and hardware resources. That is, a processor such as a CPU (Central Processing Unit) (not shown) provided in the vehicle control device 120 loads into memory and executes a program that realizes each function of the vehicle control device 120, thereby realizing each function performed by the vehicle control device 120.

[0057] Therefore, the processing performed by the vehicle control device 120 described above can be considered to be a power control method in which the processor executes a program recorded in memory, and the processor sets the power to be received from the system power supply 400 based on a signal output by the server 500, which is an external device, for a work machine that operates on power from the system power supply 400 and power from the high-voltage storage battery 112, etc.

[0058] The program for realizing this embodiment can be provided not only by communication means but also by being stored on a recording medium such as a CD-ROM.

[0059] Although the present embodiment has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the claims that various modifications and improvements to the above embodiment are also included in the technical scope of the present invention.

[0060] 1...power control system, 14, 16, 17...hydraulic cylinder (working device), 100...electric shovel (working machine, own device), 110...high voltage circuit, 111...AC / DC converter (power receiving device), 112...high voltage storage battery (battery), 120...vehicle control device, 121...control calculation function unit (processor), 122...data recording unit (memory), 125...first data transmission / reception unit (first data communication device), 130...hydraulic circuit, 200...power cable, 300...reel-type cable container, 400...system power supply, 500...server (external device, management device), 520...control device, 530...database

Claims

1. A work machine comprising: a vehicle body including a work implement; a power receiving device provided on the vehicle body for receiving power from a power grid; and a battery provided on the vehicle body, the work machine being operated using power received from the power grid by the power receiving device and power from the battery, the work machine comprising: a first data communications device for receiving information output by an external device; and a vehicle control device for setting the power to be received from the power grid based on the information received by the first data communications device.

2. The work machine described in claim 1, wherein the first data communication device transmits power consumption information, which is information about the power consumed by the vehicle body, to the external device and receives information about new power determined by the external device based on the power consumption information, and the vehicle control device sets the power to be received from the system power source based on the information about the new power determined by the external device received by the first data communication device.

3. A work machine as described in claim 2, wherein the first data communication device transmits key ON / OFF information of the vehicle body to the external device, and the external device receives the new power information determined based on information on the power consumed during the period when the vehicle body is operating, which is determined from the power consumption information and the key ON / OFF information.

4. A work machine as described in claim 2, wherein the first data communication device transmits battery remaining capacity information, which is information about the remaining capacity of the battery, to the external device, and the external device receives information about the new power determined based on the power consumption information and the battery remaining capacity information.

5. A power control method in which a processor executes a program recorded in a memory to set the power to be received from a power grid for a work machine that operates on power from a power grid and power from a battery, based on a signal output from an external device.

6. A power control system comprising: a management device that determines a plurality of distribution powers for distributing power received from a system power source to a plurality of work machines, based on a total power consumption when the work machines are operating using power from a system power source and power from a battery; and a vehicle control device that is mounted on the work machines and sets the power that the work machines receive from the system power source to the distribution power determined by the management device.

7. The power control system according to claim 6, wherein the management device receives a plurality of pieces of power consumption information, which is information on power consumed by the bodies of the plurality of work machines, and a contract power value, which is power that can be obtained from the system power source, determines the total power consumption based on the plurality of pieces of power consumption information, determines a plurality of distribution powers to be distributed to each of the plurality of work machines based on the total power consumption, the plurality of pieces of power consumption information, and the contract power value, so that power is distributed to the plurality of work machines within a range in which the sum of the plurality of distribution powers does not exceed the contract power value, and transmits information on the determined plurality of distribution powers to each of the plurality of work machines.

Images