Battery control system, work vehicle, and control method

Abstract

To appropriately control the battery charging current and reduce the risk of the battery overheating and limiting output during operation after charging. [Solution] The battery control system 1 that controls the battery 4 of a hydraulic excavator 100 equipped with a work machine acquires planned work information indicating the expected work mode and work time after charging the battery 4, and based on the planned work information, sets a first threshold temperature T which is the target temperature when charging is complete. T To determine the first threshold temperature T when charging is complete. T Determine the limiting current I1 such that the first threshold temperature T is determined. T The power controller 3 performs the following: determining the charging current relative to the battery temperature during charging based on the limiting current I1.

Description

Technical Field

[0001] The present disclosure relates to a battery control system, a work vehicle, and a control method.

Background Art

[0002] Patent Document 1 discloses a battery control method that can control the Joule heat generated by a battery during charging and charge the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Work vehicles such as construction machinery have a higher output during operation than automobiles. In addition, there may be no space to add a cooling function to the work vehicle, and the battery is often at a high temperature. Therefore, when charging using the technology described in Patent Document 1, the temperature may be high after charging. In this case, if the work vehicle is operated after charging, the temperature of the battery may further increase, and there is a risk that it cannot operate sufficiently due to the output limitation of the battery.

Means for Solving the Problems

[0005] According to the present disclosure, there is provided a battery control system for controlling a battery of a work vehicle equipped with a working machine, the system including a controller that performs: acquiring planned work information indicating a work mode and work time assumed after charging of the battery; determining a target temperature at the end of charging based on the planned work information; determining a limiting current such that the target temperature is reached at the end of charging; and determining a charging current with respect to the battery temperature during charging based on the determined target temperature and the limiting current.

[0006] According to the present disclosure, there is provided a work vehicle including the above battery control system and a working machine.

[0007] According to the present disclosure, there is provided a control method for controlling a battery of a work vehicle equipped with a working machine, the method including: acquiring planned work information indicating a work mode and work time assumed after charging of the battery; determining a target temperature at the end of charging based on the planned work information; and determining a limiting current such that the target temperature is reached at the end of charging, which is performed by a controller included in a battery control system.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to appropriately control the charging current of the battery and reduce the occurrence of the battery becoming hot during operation after charging and being output-limited.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an example of a battery control system according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing an example of a battery control system according to an embodiment. [Figure 3] FIG. 3 is a block diagram showing a computer system according to an embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a charging current with respect to a battery temperature. [Figure 5] Figure 5 shows another example of charging current as a function of battery temperature. [Figure 6] Figure 6 shows an example of the relationship between time and battery temperature. [Figure 7] Figure 7 shows the time change in battery temperature when operating at maximum load in work mode. [Figure 8] Figure 8 shows the time-dependent changes in battery temperature during charging and operation. [Figure 9] Figure 9 is a flowchart showing the battery control method according to the embodiment. [Modes for carrying out the invention]

[0010] The embodiments described below will be explained with reference to the drawings, but the disclosure is not limited thereto. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

[0011] [Embodiment] Figure 1 is a schematic diagram showing an example of a battery control system according to an embodiment. Figure 2 is a block diagram showing an example of a battery control system according to an embodiment. In the embodiment, the battery control system 1 is applied to a work vehicle such as a construction machine such as a hydraulic excavator that is powered by a battery. The work vehicle 100 has a rechargeable energy storage device, such as a battery 4, and is powered by electricity supplied from the battery 4. In the embodiment, the work vehicle 100 is a small hydraulic excavator. In the following description, the work vehicle 100 will be referred to as a hydraulic excavator 100 as appropriate. The work vehicle 100 is a rechargeable work vehicle.

[0012] <Work Vehicles> As shown in Figures 1 and 2, the hydraulic excavator 100 comprises a hydraulic pump 16, a main valve 15, a work implement cylinder 11, a slewing motor 12, and a travel motor 13. The hydraulic pump 16 supplies hydraulic fluid to the work implement cylinder 11, the slewing motor 12, and the travel motor 13 via the main valve 15. The work implement cylinder 11 generates power using the hydraulic pressure of the hydraulic fluid supplied from the hydraulic pump 16. The work implement of the hydraulic excavator 100 operates using the power generated by the work implement cylinder 11. The slewing motor 12 generates power using the hydraulic pressure of the hydraulic fluid supplied from the hydraulic pump 16. The hydraulic excavator 100 rotates using the power generated by the slewing motor 12. The travel motor 13 generates power using the hydraulic pressure of the hydraulic fluid supplied from the hydraulic pump 16. The hydraulic excavator 100 travels using the power generated by the travel motor 13.

[0013] The inverter 19 of the hydraulic excavator 100 is electrically connected to the battery 4. The motor 18, which is the load, is connected to the inverter 19. The inverter 19 supplies power to the motor 18. The motor 18 is connected to the hydraulic pump 16.

[0014] <Battery control system> The battery control system 1 for the hydraulic excavator 100 comprises a charger 2, a power controller 3, a battery 4, and a monitor 5.

[0015] Charger 2 charges battery 4. Charger 2 may be a standard charger or a fast charger. Charger 2 may be installed on the hydraulic excavator 100 or on the outside of the hydraulic excavator 100. Charger 2 converts AC power input from an external source into DC power suitable for charging.

[0016] Battery 4 supplies the power required to drive the hydraulic excavator 100. In other words, battery 4 is a high-voltage drive battery. Battery 4 is rechargeable and can be charged, for example, overnight or during lunch breaks. The charging and discharging of battery 4 are controlled by the power controller (controller) 3.

[0017] The battery 4 includes temperature sensors 6, such as an internal temperature sensor and an ambient temperature sensor. The temperature sensors 6 transmit the measured temperature data to the power controller 3.

[0018] The internal temperature sensor measures the battery temperature of battery 4. The internal temperature data measured by the internal temperature sensor is transmitted to the power controller 3.

[0019] The ambient temperature sensor measures the ambient temperature around the battery 4. The ambient temperature data measured by the ambient temperature sensor is transmitted to the power controller 3.

[0020] Monitor 5 is implemented using, for example, an organic EL or liquid crystal display screen. Monitor 5 has a display unit that displays various information, including operating information of the hydraulic excavator 100, an operation unit 7 into which various instructions or information are input by the operator, and a display unit controller implemented using a CPU or the like.

[0021] Monitor 5 displays various information related to charging on its display unit, for example. Monitor 5 can accept various operations, such as starting and stopping charging, via the operation unit 7.

[0022] Monitor 5 can accept input, for example, via the control unit 7, for the expected work mode and work time after charging. For example, just before the operator initiates the charging process, Monitor 5 displays a screen allowing the operator to select or input the expected work mode and work time after charging.

[0023] The operating mode can be selected or entered from multiple operating modes, such as power mode and eco mode, as well as a sleep mode.

[0024] The work time can be selected or entered in increments of approximately 15 minutes, for example.

[0025] <Power Controller> Figure 3 is a block diagram showing a power controller, which is a controller of the battery control system according to the embodiment. The power controller 3 controls the charging and discharging of the battery 4. The power controller 3 is electrically connected to the battery 4 and the monitor 5. The power controller 3 includes a numerical processing unit (processor), such as a CPU (Central Processing Unit). The power controller 3 is composed of one or more numerical processing units.

[0026] Figure 3 is a block diagram showing a computer system according to an embodiment. The power controller 3 includes a computer system 1000. The computer system 1000 includes a processor 1001 such as a CPU, a main memory 1002 including non-volatile memory such as ROM (Read Only Memory) and volatile memory such as RAM (Random Access Memory), a storage 1003, and an interface 1004 including input / output circuits. The functions of the power controller 3 described above are stored as a program in the storage 1003. The processor 1001 reads the program from the storage 1003, loads it into the main memory 1002, and executes the above-mentioned processing according to the program. The program may be distributed to the computer system 1000 via a network.

[0027] The power controller 3 determines that the battery temperature at the start of charging is the first threshold temperature (target temperature) T T If the following conditions are met, the rated current I R It charges at the first threshold temperature T. T This is the target temperature of the battery 4 at the completion of charging, determined based on the scheduled work information. First threshold temperature T T The decision will be discussed later.

[0028] The power controller 3 determines that the battery temperature at the start of charging is the first threshold temperature T T Higher second threshold temperature (battery limit temperature) T L If the temperature exceeds the second threshold temperature T, charging will be stopped. Lis the limit temperature determined by the battery characteristics and is a constant.

[0029] The power controller 3 charges as follows. First, the power controller 3 acquires scheduled operation information indicating the operation mode and operation time assumed after charging the battery 4, and based on the scheduled operation information, determines the first threshold temperature T of the battery 4 at the time of charging completion T and determines a limit current I1 such that the first threshold temperature T T is reached at the time of charging completion. Then, the power controller 3 performs charging based on the determined first threshold temperature T T the limit current I1, and the battery temperature.

[0030] Explanation of the acquisition of scheduled operation information. The power controller 3 acquires, for example, scheduled operation information indicating the operation mode and operation time assumed after charging, which is input by the operator via the monitor 5. When there is no input of scheduled operation information to the monitor 5, the power controller 3 may predict the operation mode and operation time after charging from the accumulated data, which is the history of the operation mode and operation time after charging stored in a storage unit not shown, and acquire it as scheduled operation information. When acquiring from the accumulated data, for example, the operation mode and operation time after charging on the previous day may be acquired as scheduled operation information. Also, for example, the scheduled operation information may be acquired from the accumulated data transmitted from a plurality of work vehicles to an external server device not shown and stored in the storage unit. <00002​​​​​​The power controller 3 determines the expected temperature rise ΔT of the battery 4 after charging based on the work mode and work time of the scheduled work information. If the work mode is the idle mode, the power controller 3 sets the expected temperature rise ΔT to 0 (zero). The expected temperature rise ΔT is a value estimated by the work mode and work time. The expected temperature rise ΔT may also be estimated by considering the battery temperature obtained from the battery 4's temperature sensor and the ambient temperature. For example, the power controller 3 determines the expected temperature rise ΔT based on correlation data showing the relationship between the work mode, work time and the expected temperature rise ΔT. The correlation data for determining the expected temperature rise ΔT may be derived, for example, from measured values ​​of the battery temperature rise measured by a cycle test of the operation and charging of the hydraulic excavator 100. The correlation data for determining the expected temperature rise ΔT is predetermined and stored in a memory unit not shown in the figure. Then, the power controller 3 uses the determined expected temperature rise ΔT of the battery 4 to determine the first threshold temperature T T Determine the first threshold temperature T. T is, T T =T L Determined by -ΔT

[0032] The determination of the limiting current I1 is explained. The battery temperature at the start of charging is the first threshold temperature T. T If the above conditions are met, the battery temperature needs to be lowered during charging. The small hydraulic excavator 100 of this embodiment does not have a function to cool the battery 4. Therefore, the heat from the battery 4 needs to be released by natural heat dissipation during charging. If the charging current to the battery 4 is set to 0 [A], charging will not be possible. Therefore, it is necessary to supply a small amount of charging current to lower the battery temperature while charging. Accordingly, the power controller 3 determines that the battery temperature at the start of charging is the first threshold temperature T T If higher, the battery temperature during charging is lowered to the first threshold temperature T. T The limiting current I1 is determined such that the battery temperature at the start of charging is the first threshold temperature T. TThe limiting current I1 is determined by allowing a rise in battery temperature during charging if the following conditions are met. For example, the power controller 3 determines the limiting current I1 based on correlation data showing the relationship between the battery temperature at the start of charging and the limiting current I1. The correlation data for determining the limiting current I1 may be derived, for example, by a cycle test of the operation and charging of the hydraulic excavator 100. The correlation data for determining the limiting current I1 is stored in advance in a memory unit (not shown).

[0033] The power controller 3 determines the first threshold temperature T T Based on the limiting current I1, the charging current is determined in relation to the battery temperature during charging.

[0034] Figure 4 shows an example of charging current in relation to battery temperature. In the example shown in Figure 4, the power controller 3 charges the battery when the battery temperature reaches the first threshold temperature T T If the following conditions are met, a constant rated current I R The battery is charged. Power controller 3 will set the battery temperature to the first threshold temperature T when the battery temperature is reached. T The above and the second threshold temperature T L The power controller 3 charges the battery at the limiting current I1 if the following conditions are met: L If it is greater than that, the charging current is set to 0 [A].

[0035] Figure 5 shows another example of charging current with respect to battery temperature. In the example shown in Figure 5, the power controller 3 charges the battery when the battery temperature reaches the first threshold temperature T T If the following conditions are met, the rated current I R The charging current is gradually reduced from the first threshold temperature T to the limit current I1. The power controller 3 detects when the battery temperature reaches the first threshold temperature T. T The above and the second threshold temperature T L If the following conditions are met, the charging current is gradually reduced from the limiting current I1 to 0 (zero) [A] to charge the battery. The power controller 3 controls the battery temperature when it reaches the second threshold temperature T L If it is greater than that, the charging current is set to 0 [A].

[0036] Figure 6 shows an example of the relationship between time and battery temperature. Figure 6 shows an example where the battery operates in the morning, is rapidly charged during the lunch break, operates in the afternoon, and is charged overnight. During the first charge (lunch break) after the first (morning) operation, charging is performed in a way that lowers the battery temperature. During the first (lunch break) charge, the first threshold temperature T of the battery 4 is set according to the expected temperature rise ΔT of the battery 4 in the work mode assumed for the second (afternoon) operation after charging. T This is set. The battery temperature after the end of the second (afternoon) operation is the second threshold temperature T L Therefore, during the second operation (afternoon), the battery temperature reached the second threshold temperature T. L It will not exceed this limit, and its operation will not be restricted.

[0037] <Control Method> Figure 9 is a flowchart showing a battery control method according to an embodiment. For example, when charging of the battery 4 of the hydraulic excavator 100 is started, the battery control system 1 is activated. When the battery control system 1 is activated, the processing shown in the flowchart in Figure 9 is started and the control method is executed.

[0038] The power controller 3 determines whether or not there is input for the work mode and work time after charging (step ST11). The power controller 3 determines that there is input if it receives an operation via the operation unit 7 of the monitor 5 to input the expected work mode and work time after charging. If the power controller 3 determines that there is input for the work mode and work time after charging (step ST11; Yes), it proceeds to step ST13. If the power controller 3 does not determine that there is input for the work mode and work time after charging (step ST11; No), it proceeds to step ST12.

[0039] If it is determined that there is no input for the work mode and work time after charging (step ST11; No), the power controller 3 determines the work mode and work time after charging from the stored data (step ST12). The power controller 3 predicts the work mode and work time after charging from the stored data, which is the history of the work mode and work time after charging stored in a memory unit (not shown), and acquires it as scheduled work information. The power controller 3 proceeds to step ST14.

[0040] If it is determined that there is input for the work mode and work time after charging (step ST11; Yes), the power controller 3 determines the work mode and work time after charging as input values ​​(step 13). The power controller 3 obtains planned work information, which indicates the expected work mode and work time after charging, for example, input by the operator via the operation unit 7 of the monitor 5. The power controller 3 proceeds to step ST14.

[0041] The power controller 3 controls the first threshold temperature T of the battery 4. T (Step ST14) The power controller 3 sets the first threshold temperature T of the battery 4 at the completion of charging, according to the expected temperature rise ΔT of the battery 4 in the work mode expected after charging, based on the scheduled work information. T The power controller 3 then proceeds to step ST15.

[0042] The power controller 3 determines that the battery temperature at the start of charging is the first threshold temperature T T It is determined whether it is greater than or less than (step ST15). The power controller 3 determines if the battery temperature at the start of charging is the first threshold temperature T T If it is determined to be greater than (step ST15; Yes), proceed to step ST16. Power controller 3 determines that the battery temperature at the start of charging is the first threshold temperature T T If it is not determined to be greater than (Step ST15; No), proceed to Step ST18.

[0043] The battery temperature at the start of charging is the first threshold temperature T. TIf it is determined to be greater (step ST15; Yes), the limiting current I1 is determined to lower the temperature during charging (step ST16).

[0044] The battery temperature at the start of charging is the first threshold temperature T. T If it is not determined to be greater than (Step ST15; No), the limiting current I1 is determined while allowing the temperature rise during charging (Step ST18).

[0045] The power controller 3 charges the battery 4 with a charging current based on the battery temperature and the limiting current determined as described above.

[0046] <effect> In this embodiment, the second threshold temperature T L <If the battery temperature is high, the charging current will be reduced to 0[A] to protect battery 4.

[0047] In this embodiment, the first threshold temperature T T ≤ Battery temperature ≤ Second threshold temperature T L In this case, the battery temperature is lowered while charging, and the battery temperature at the end of charging is set to the first threshold temperature T. T The following applies:

[0048] In this embodiment, the battery temperature < first threshold temperature T T If so, the first threshold temperature T T The battery temperature can rise up to this point, so the rated current I R Charge it with this.

[0049] Figure 6 shows an example of the time change in battery temperature when charging is controlled by charging current for each temperature range. The battery temperature at the start of charging is the first threshold temperature T. T It is higher. Therefore, the battery temperature is lowered while charging, and the first threshold temperature T is reached when charging is complete. T It is necessary to do so. By using the charge control of the embodiment, the battery temperature at the completion of charging is the first threshold temperature T T Once fully charged, the device can operate in the user's requested work mode and for the specified duration.

[0050] <Effects> As described above, in this embodiment, the first threshold temperature T at the time of charging completion is determined based on the scheduled work information. T And, when charging is complete, the first threshold temperature T T Based on the limiting current I1 determined to be such that the charging current can be determined in relation to the battery temperature during charging. According to this embodiment, the charging current of the battery 4 can be appropriately controlled to reduce the likelihood of the battery 4 becoming overheated and limiting its output during operation after charging. According to this embodiment, as shown in Figure 6, the workload of the hydraulic excavator 100 can be maintained without limitations during afternoon operation.

[0051] In this embodiment, based on the planned work information, the first threshold temperature T is determined according to the expected temperature rise ΔT of the battery 4 in the work mode assumed after charging. T The first threshold temperature T can be determined by considering the assumed temperature rise ΔT of the battery 4 after operation. T This can be determined. According to the embodiment, it is possible to reduce the risk of the battery 4 becoming overheated and limiting its output during operation after charging.

[0052] In this embodiment, the first threshold temperature T is reached when charging is complete. T The limiting current I1 can be determined in such a way. According to this embodiment, the charging current of the battery 4 can be appropriately controlled considering the expected temperature rise ΔT of the battery 4 after operation.

[0053] In this embodiment, the temperature of the battery 4 at the start of charging is the first threshold temperature T T If the value is higher, the limiting current I1 can be determined to lower the temperature of the battery 4 during charging. According to this embodiment, the charging current of the battery 4 can be appropriately controlled.

[0054] In this embodiment, the temperature of the battery 4 at the start of charging is the first threshold temperature T TThe limiting current I1 can be determined while allowing a rise in the temperature of the battery 4 during charging, provided the following conditions are met. According to this embodiment, the charging current of the battery 4 can be appropriately controlled.

[0055] In this embodiment, the temperature of the battery 4 is the first threshold temperature T T A lower first threshold temperature T T If the following conditions are met, the rated current I R It can be charged using [a specific method]. According to this embodiment, if the battery temperature is sufficiently low at the start of charging, it can be charged efficiently without limitations, and after charging is complete, it can be used in the work mode and for the work time requested by the user.

[0056] In this embodiment, the temperature of the battery 4 is the first threshold temperature T T A higher second threshold temperature T L If the above conditions are met, charging can be stopped.

[0057] In this embodiment, instead of simply limiting the charging current, a limiting current I1 is set that allows charging while lowering the temperature during charging, enabling efficient charging. According to this embodiment, charging control can be performed to sufficiently lower the battery temperature, taking into account the temperature rise during operation. [Explanation of symbols]

[0058] 1...Battery control system, 2...Charger, 3...Power controller, 4...Battery, 5...Monitor, 6...Temperature sensor, 7...Operation unit, 11...Work machine cylinder, 12...Slewing motor, 13...Travel motor, 15...Main valve, 16...Hydraulic pump, 18...Motor, 19...Inverter, I1...Limiting current, I R …Rated current, T T ...First threshold temperature (target temperature), T L ...Second threshold temperature, ΔT...Assumed temperature rise.

Claims

1. A battery control system for controlling the battery of a work vehicle equipped with work implements, After charging the aforementioned battery, the system acquires planned work information indicating the expected work mode and work time, Based on the aforementioned scheduled work information, the target temperature at the completion of charging is determined, Determine the limiting current such that the target temperature is reached when charging is complete, Based on the determined target temperature and limiting current, the charging current is determined for the battery temperature during charging, A controller that executes A battery control system equipped with this feature.

2. The aforementioned controller, Based on the aforementioned scheduled work information, the target temperature is determined according to the expected temperature rise of the battery in the work mode assumed after charging. The battery control system according to claim 1.

3. The aforementioned controller, If the battery temperature at the start of charging is higher than the target temperature, the limiting current is determined to lower the battery temperature during charging. The battery control system according to claim 1.

4. The aforementioned controller, If the battery temperature at the start of charging is below the target temperature, the limiting current is determined while allowing the battery temperature to rise during charging. The battery control system according to claim 1.

5. The aforementioned controller, If the battery temperature at the start of charging is below the first threshold temperature, which is lower than the target temperature, charging is performed at the rated current. The battery control system according to claim 1.

6. The aforementioned controller, If the battery temperature at the start of charging is above a second threshold temperature, which is higher than the target temperature, charging is stopped. The battery control system according to claim 1.

7. A battery control system according to any one of claims 1 to 6, Work equipment and A work vehicle equipped with the following features.

8. A control method for controlling the battery of a work vehicle equipped with a work implement, After charging the aforementioned battery, the system acquires planned work information indicating the expected work mode and work time, Based on the aforementioned scheduled work information, the target temperature at the completion of charging is determined, Determining the limiting current such that the target temperature is reached when charging is complete, A control method performed by a controller equipped in a battery control system.

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