control device

Abstract

To provide a control device which can stably execute balance processing.SOLUTION: In a control device, a first power storage part has a plurality of battery cells, and supplies power to a load. A switching part switches between start and stop of the load. A power supply part can supply power from the first power storage part to a second power storage part. A characteristic value derivation part derives a characteristic value indicating variation in each voltage of the plurality of battery cells. A balance processing part can execute balance processing of reducing the variation in the voltage. When the switching part is switched to stop, and the characteristic value derived by the characteristic value derivation part is equal to or more a first threshold, a control part transmits a first command of instructing to supply power from the first power storage part to the second power storage part, to the power supply part, and transmits a second command of instructing to execute the balance processing to the balance processing part.SELECTED DRAWING: Figure 3

Description

Technical Field

[0005]

[0001] The present invention relates to a control device.

Background Art

[0002] A working machine according to the background art is driven by electric power supplied from a battery pack under the control of a control device. The battery pack is composed of a plurality of battery modules. In each battery module, a plurality of battery cells are connected in series. The working machine further includes a lead battery. The lead battery is a battery with a lower voltage than the battery pack. Also, the lead battery supplies driving power to the control device. The control device executes a balancing process within a time range in which the voltage of a lead battery other than the battery pack becomes equal to or higher than a predetermined voltage value and the charge rate of the battery pack becomes equal to or higher than a predetermined charge rate value after the key switch of the working machine is switched from on to off. By the balancing process, variations in the energy capacity of each battery cell are suppressed (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the background art has a problem that the balancing process is not stably executed. Specifically, after the key switch is turned off, depending on the usage situation of the lead battery, the voltage of the lead battery may not become equal to or higher than the predetermined voltage value. In this case, the balancing process is not executed.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a control device capable of stably executing a balancing process. [Means for solving the problem]

[0006] The control device according to the present invention comprises a first energy storage unit, a switching unit, a second energy storage unit, a power supply unit, a characteristic value derivation unit, a balance processing unit, and a control unit. The first energy storage unit has a plurality of battery cells and supplies power to a load. The switching unit switches the load between starting and stopping. The second energy storage unit is chargeable and dischargeable. The power supply unit can supply power from the first energy storage unit to the second energy storage unit. The characteristic value derivation unit derives characteristic values ​​that show the voltage variation of each of the plurality of battery cells. The balance processing unit can perform a balance processing to reduce the voltage variation. The control unit receives power from the second energy storage unit. When the switching unit is switched to stop and the characteristic value derived by the characteristic value derivation unit is equal to or greater than the first threshold, the control unit transmits a first command to the power supply unit instructing the first power storage unit to supply power to the second power storage unit, and transmits a second command to the balance processing unit instructing the balance processing to be executed. [Effects of the Invention]

[0007] According to the present invention, the balancing process is performed stably. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram of a work machine equipped with a control device according to an embodiment. [Figure 2] This block diagram shows an example of a battery pack configuration as shown in Figure 1. [Figure 3] Figure 1 is a flowchart showing the processing of the control device. [Figure 4] This flowchart shows a first modified example of the processing of the control device shown in Figure 1. [Figure 5] This figure shows the relationship between characteristic values ​​and the first, second, and third thresholds. [Figure 6] This flowchart shows a second modified example of the processing of the control device shown in Figure 1. [Figure 7] This flowchart shows a third modified example of the processing of the control device shown in Figure 1. [Figure 8] This figure shows an example of the display screen of the display shown in Figure 1. [Figure 9] This is a block diagram of a work machine equipped with a control device according to the fifth modified example. [Modes for carrying out the invention]

[0009] Embodiments and various modifications of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and will not be repeated in the description.

[0010] [Embodiment] Hereinafter, with reference to Figure 1, a work machine 200 equipped with a control device 100 according to one embodiment of the present invention will be described. The work machine 200 is, for example, a hydraulic excavator or a wheel loader. Figure 1 is a block diagram of the work machine 200 equipped with the control device 100 according to the embodiment. As shown in Figure 1, the work machine 200 includes the control device 100, an electric motor 201 as a load, a hydraulic pump 202, a control valve 203, and a hydraulic actuator 204.

[0011] The electric motor 201 is, for example, a three-phase AC motor, which generates driving force when AC power is supplied from the inverter 3. The hydraulic pump 202 is operated by the driving force from the electric motor 201. As a result, hydraulic fluid is supplied to the hydraulic actuator 204 via the control valve 203. The hydraulic actuator 204 is, for example, a boom cylinder, an arm cylinder, a tool cylinder, a swing hydraulic cylinder, or a slewing hydraulic cylinder.

[0012] The control device 100 is electrically connected to the electric motor 201 and controls the power supply to the electric motor 201. The control device 100 includes a rectifier 1, a battery pack 2, an inverter 3, a DC-DC converter (hereinafter abbreviated as "converter") 4, a low-voltage battery 5, an ECU (Electronic Control Unit) 6, a self-holding circuit 7, a key switch 8, and a display 9.

[0013] Battery pack 2 is an example of a first energy storage unit. Converter 4 is an example of a power supply unit. Low-voltage battery 5 is an example of a second energy storage unit. ECU 6 is an example of a control unit. Key switch 8 is an example of a switching unit. Display 9 is an example of a display unit.

[0014] Rectifier 1 can receive AC voltage (AC power) from an external power source 300 via a power supply path 301. The external power source 300 is, for example, a commercial power source or a power supply device. The power supply path 301 is, for example, a power cable. Rectifier 1 is further electrically connected to a battery pack 2 and an inverter 3. When the operating mode of the work machine 200 is the first mode, rectifier 1 converts the AC voltage to DC voltage and supplies the converted DC voltage to the battery pack 2. When the operating mode is the second mode, rectifier 1 further converts the AC voltage to DC voltage and supplies the converted DC voltage to the inverter 3. When the operating mode is the third mode, rectifier 1 further disconnects the power supply path from rectifier 1 to the battery pack 2 and inverter 3. As a result, DC voltage is supplied to the inverter 3 by the battery pack 2. The first mode, second mode, and third mode can be selectively switched by a mode switch (not shown) provided on the work machine 200.

[0015] Battery pack 2 is a rechargeable secondary battery. Battery pack 2 is typically a lithium-ion battery. In the first mode, battery pack 2 is charged by a DC voltage supplied from rectifier 1. In the third mode, battery pack 2 supplies a DC voltage to inverter 3 by discharging.

[0016] The inverter 3 converts the DC voltage supplied from the rectifier 1 or the battery pack 2 into an AC voltage and supplies the converted AC voltage to the electric motor 201. In other words, the battery pack 2 supplies an AC voltage to the electric motor 201 as a load via the inverter 3.

[0017] The converter 4 steps down the DC voltage supplied from the battery pack 2 and converts it into a DC voltage suitable for charging the low-voltage battery 5. The converter 4 supplies the converted DC voltage to the low-voltage battery 5. That is, the converter 4 can supply power from the battery pack 2 to the low-voltage battery 5.

[0018] The low-voltage battery 5 is a rechargeable secondary battery. The low-voltage battery 5 is not limited to a lithium-ion battery and may be a lead-acid battery. The low-voltage battery 5 is charged by receiving a DC voltage from the converter 4. When the low-voltage battery 5 is electrically connected to the ECU 6 via the power supply path 101, it supplies a DC voltage to the ECU 6.

[0019] The ECU 6 operates with the DC voltage from the low-voltage battery 5. That is, the ECU 6 receives power supply from the low-voltage battery 5. The ECU 6 has various ICs mounted on the circuit board. The various ICs are, for example, a power supply circuit and a microcomputer. The microcomputer has a built-in memory. Note that the memory may be mounted on the circuit board as an IC separate from the microcomputer. The memory stores a control program and various data. When the microcomputer starts operating, it starts executing the control program and controls each component of the construction machine 200.

[0020] The self-holding circuit 7 is a circuit that holds the operation of a relay located on the power supply path 101. When a start signal is input from the key switch 8, the self-holding circuit 7 turns on the relay. As a result, the ECU 6 and the low-voltage battery 5 are electrically connected via the power supply path 101. That is, power supply from the low-voltage battery 5 to the ECU 6 begins. When a release signal is input from the ECU 6, the self-holding circuit 7 turns off the relay. As a result, the power supply path 101 is interrupted.

[0021] The key switch 8 is located near the steering wheel (not shown) of the work machine 200. The key switch 8 is a switch that switches the work machine 200 on (i.e., on) and off (i.e., off) by operation by an operator. In other words, the key switch 8 switches the start and stop of the electric motor 201, which is the load. When the key switch 8 is switched to start, it transmits a start signal to the self-holding circuit 7. When the key switch 8 is switched to start, the engine (not shown) of the work machine 200 starts. Conversely, when the key switch 8 is switched to stop, it transmits a stop signal to the ECU 6. When the key switch 8 is switched to stop, the engine stops.

[0022] *The configuration of claim 6 Display 9 is located near the driver's seat (not shown) of the work machine 200. Display 9 displays images on its screen that are represented by various image data transmitted from the ECU 6. In particular, Display 9 displays images related to the balancing process (described later) on its screen while the balancing process is being performed.

[0023] Next, we will describe the details of the battery pack 2 with reference to Figure 2. Figure 2 is a block diagram showing an example configuration of the battery pack 2 shown in Figure 1. As shown in Figure 2, the battery pack 2 comprises four battery modules 21 and a BMU (Battery Management Unit) 22. Note that the battery modules 21 are also called battery packs. The number of battery modules 21 can be one or more.

[0024] Each battery module 21 has a CMU (Cell Management Unit) 211, four battery cells 212, four cell balancing circuits 213, and four voltage detection circuits 214. In other words, the battery pack 2 has multiple battery cells 212. For convenience, in Figure 2, the reference numerals "211", "212", "213", and "214" are assigned to one CMU, one battery cell, one cell balancing circuit, and one voltage detection circuit.

[0025] The CMU211 controls the state of the four battery cells 212 in the same battery module 21.

[0026] Each battery cell 212 is rechargeable and dischargeable. A total of 16 battery cells 212 are provided in the battery pack 2. The 16 battery cells 212 are connected in series. In addition, one cell balancing circuit 213 and one voltage detection circuit 214 are connected in parallel to each of the 16 battery cells 212.

[0027] Each cell balancing circuit 213 has a discharge resistor and a switching element. The switching element is turned on and off under the control of a CMU (hereinafter referred to as "corresponding CMU") 211 included in the same battery module 21. While the switching element is on, the battery cell 212 connected in parallel with the discharge resistor discharges. As a result, the variation in cell voltage of the battery pack 2 is reduced.

[0028] Each voltage detection circuit 214, under the control of the corresponding CMU 211, detects the voltage of the battery cell 212 connected in parallel with itself (hereinafter referred to as "cell voltage") and outputs the detected cell voltage to the corresponding CMU 211.

[0029] The BMU22 controls the state of the four battery modules 21 included in the battery pack 2. The BMU22 is an example of a characteristic value derivation unit, and it acquires the cell voltage from each voltage detection circuit 214 from each CMU214. The BMU22 derives a characteristic value that shows the variation of each acquired cell voltage. The BMU22 outputs the derived characteristic value to the ECU6. In detail, the characteristic value is the difference between the maximum and minimum values ​​for all cell voltages.

[0030] Next, the processing of the control device 100 will be explained in detail with reference to Figures 1 to 3. Figure 3 is a flowchart showing the processing of the control device 100 as shown in Figure 1.

[0031] As shown in Figure 3, when the control program is running, in step S101, the ECU 6 receives a stop signal from the key switch 8 and sends a request to the BMU 22 to transmit characteristic values.

[0032] In step S102, the BMU22 acquires cell voltages from each voltage detection circuit 214 in response to the transmission request. The BMU22 derives characteristic values ​​based on the acquired cell voltages. The BMU22 transmits the derived characteristic values ​​to the ECU6.

[0033] In step S103, the ECU6 determines whether the received characteristic value is greater than or equal to a first threshold. The first threshold is a reference value indicating whether the variation in cell voltage is large or small. If the ECU6 determines that the characteristic value is not greater than or equal to the first threshold (No in step S103), it executes step S104. On the other hand, if the ECU6 determines that the characteristic value is greater than or equal to the first threshold (Yes in step S103), it executes step S105.

[0034] In step S104, the ECU 6 sends a release signal to the self-holding circuit 7. Upon receiving the release signal, the self-holding circuit 7 cuts off the power supply path 101 by turning off the relay. As a result, the work machine 200 stops.

[0035] Step S105 is executed when the key switch 8 is switched to stop and the characteristic value derived by the BMU 22 is greater than or equal to the first threshold. In step S105, the ECU 6 sends a first command to the converter 4 and a second command to the BMU 22. The first command is a command to instruct the battery pack 2 to supply power to the low-voltage battery 5. The second command is a command to instruct the execution of the balancing process.

[0036] In response to receiving the first command, the converter 4 supplies a DC voltage from the battery pack 2 to the low-voltage battery 5, thereby charging the low-voltage battery 5. Consequently, the ECU 6 is continuously supplied with DC voltage from the low-voltage battery 5. As a result, the following balancing process is stably performed.

[0037] Upon receiving the second command, the BMU22 instructs each CMU211 to perform the balancing process. Each CMU211 identifies at least one target battery cell 212 from among the four battery cells 212 in the same battery module 21. The target battery cell 212 includes at least the battery cell 212 with the highest cell voltage. Each CMU211 turns on the switching elements of the cell balancing circuit (hereinafter referred to as the "corresponding cell balancing circuit") 213 connected in parallel to the target battery cell 212. As a result, the target battery cell 212 discharges. Consequently, the variation in each cell voltage is reduced. Each CMU211 also turns off the switching elements of each corresponding cell balancing circuit 213 as appropriate. The conditions or timing for turning off each switching element can be those of known technology. In response to turning off the switching elements of the corresponding cell balancing circuit 213, each CMU211 sends a notification to the BMU22 indicating the completion of the balancing process. Note that BMU22 and each CMU211 are examples of balance processing units. BMU22 sends a completion notification for the balance processing in response to receiving completion notifications from all CMU211s.

[0038] Upon receiving a notification from the BMU22 that the balancing process has finished, the ECU6 terminates step S105 and executes step S104.

[0039] [First variation] Next, a first modified example of the processing of the control device 100 will be described in detail with reference to Figures 1, 2, and 4. Figure 4 is a flowchart of the first modified example of the processing of the control device 100 shown in Figure 1.

[0040] As shown in Figure 4, when the control program is running, the control device 100 executes steps S201 to S212. Of these, steps S201 to S205 are the same as steps S101 to S105 in Figure 3, so their respective explanations will be omitted.

[0041] Step S206 is performed after step S205. In step S206, the BMU22 further acquires the current cell voltage from each voltage detection circuit 214 in response to the receipt of the second command. The BMU22 derives characteristic values ​​based on the acquired cell voltages. The BMU22 transmits the derived characteristic values ​​to the ECU6.

[0042] In step S207, the ECU6 determines whether the received characteristic value has reached the third threshold. The third threshold is a reference value that is smaller than the second threshold (described later) and indicates whether the balancing process can be terminated. If the ECU6 determines that the characteristic value has reached the third threshold (Yes in step S207), it executes step S208. On the other hand, if the ECU6 determines that the characteristic value has not reached the third threshold (No in step S207), it executes step S209.

[0043] In step S208, ECU6 stops sending the second command. As a result, BMU22 stops instructing each CMU211 to perform the balancing process. After step S208 is executed, step S204 is executed.

[0044] In step S209, the ECU 6 determines whether the received characteristic value has reached the second threshold. The second threshold is smaller than the first threshold and larger than the third threshold. The second threshold is a reference value that indicates whether it is permissible to stop the power supply from the battery pack 2 to the low-voltage battery 5. If the ECU 6 determines that the characteristic value has reached the second threshold (Yes in step S209), it executes step S210. On the other hand, if the ECU 6 determines that the characteristic value has not reached the second threshold (No in step S209), it executes step S206.

[0045] In step S210, the ECU 6 stops sending the first command. Consequently, power supply from the battery pack 2 to the low-voltage battery 5 is stopped. In other words, even if balancing is being performed, if the characteristic value decreases, power supply to the low-voltage battery 5 is stopped. After step S210 is executed, step S211 is executed.

[0046] Next, in step S211, the ECU 6 determines whether the current voltage value of the low-voltage battery 5 has reached the fourth threshold. The fourth threshold is a reference value that indicates whether or not to resume power supply to the low-voltage battery 5. If it is determined that the voltage value is not below the fourth threshold (No in step S211), step S204 is executed. On the other hand, if it is determined that the voltage value is below the fourth threshold (Yes in step S211), step S212 is executed.

[0047] In step S212, the ECU 6 sends a first command to the converter 4. As a result, power supply to the low-voltage battery 5 is resumed, and the balancing process is performed stably. Therefore, when the key switch 8 is switched to the next start, the low-voltage battery 5 can stably supply power to the ECU 6. After step S212 is executed, step S204 is performed.

[0048] Next, with reference to Figure 5, the detailed effects of the first modified example will be described. Figure 5 is a diagram showing the relationship between the characteristic value and the first threshold, second threshold, and third threshold. In Figure 5 and the following description, the characteristic value, first threshold, second threshold, and third threshold are denoted by the reference symbols "Vd", "V1", "V2", and "V3", respectively.

[0049] As shown in Figure 5, when the characteristic value Vd is greater than or equal to the first threshold V1, power is supplied to the low-voltage battery 5 while the balancing process is performed. In other words, the charge level of the low-voltage battery 5 is unlikely to drop to zero while the balancing process is being performed. Therefore, the balancing process is performed stably.

[0050] As the balancing process and power supply to the low-voltage battery 5 are further performed, the characteristic value Vd gradually decreases and eventually reaches the second threshold V2. In response to the characteristic value Vd reaching the second threshold V2, the power supply to the low-voltage battery 5 is stopped. That is, discharge from the battery pack 2 is stopped. Therefore, after the characteristic value Vd reaches the second threshold V2, power supply to the low-voltage battery 5 is stopped. Thus, the variation in the characteristic value Vd caused by the discharge of the battery pack 2 is suppressed. That is, the balancing process is performed with high precision. As a result, the characteristic value Vd (i.e., variation) is suppressed even more stably. Then, in response to the characteristic value Vd reaching the third threshold V3, the execution of the balancing process is terminated.

[0051] Furthermore, after the characteristic value Vd reaches the second threshold V2, power supply to the low-voltage battery 5 is resumed in accordance with the fact that the current voltage value of the low-voltage battery 5 falls below the fourth threshold.

[0052] [Second variation] Next, a second modified example of the control device 100's processing will be described in detail with reference to Figures 1, 2, and 6. Figure 6 is a flowchart showing the second modified example of the control device 100's processing shown in Figure 1.

[0053] As shown in Figure 6, when the control program is running, the control device 100 executes steps S301 to S308. Of these, steps S301 to S306 are the same as steps S201 to S206 in Figure 4, so their respective explanations will be omitted.

[0054] Step S307 is executed after step S306. In step S306, the ECU6 determines whether the received characteristic value has reached the fifth threshold. The fifth threshold is smaller than the first threshold and is a reference value that indicates whether or not the balancing process can be terminated. If the ECU6 determines that the characteristic value has reached the fifth threshold (Yes in step S307), it executes step S308. On the other hand, if the ECU6 determines that the characteristic value has not reached the fifth threshold (No in step S307), it executes step S305.

[0055] In step S308, the ECU 6 stops transmitting the second command. As a result, the BMU 22 stops instructing each CMU 211 to perform the balancing process. In step S308, the ECU 6 further transmits a fourth command to the self-holding circuit 7. The fourth command is a command to instruct the disconnection of the power supply path 101. In response to receiving the fourth command, the self-holding circuit 7 turns off the relay. As a result, the power supply path 101 is disconnected. That is, in step S308, the completion of the balancing process and the disconnection of the power supply path 101 are performed simultaneously. Therefore, the second modified example has the effect of reducing the processing load on the ECU 6 compared to the first modified example.

[0056] [Third variation] Next, a third modified example of the control device 100's processing will be described in detail with reference to Figures 1, 2, and 7. Figure 7 is a flowchart of the third modified example of the control device 100's processing shown in Figure 1.

[0057] As shown in Figure 7, when the control program is running, the control device 100 executes steps S401 to S407. Of these, steps S401 to S405 are the same as steps S101 to S105 in Figure 3, so their explanation will be omitted.

[0058] Step S406 is executed after step S405. In step S406, the ECU6 determines whether the key switch 8 has been switched to start. If it is determined that the key switch 8 has not been switched to start (No in step S406), step S405 is executed to continue the balancing process. On the other hand, if it is determined that the key switch 8 has been switched to start (Yes in step S406), step S407 is executed to terminate the balancing process.

[0059] In step S407, the ECU 6 stops transmitting the second command and transmits the fifth command to the inverter 3. The fifth command is a command to start the electric motor 201 as a load. In response to receiving the fifth command, the inverter 3 applies an AC voltage to the electric motor 201 as a load via the inverter 3. As a result, the work machine 200 starts. According to the third modification, the work machine 200 can be used even while the balancing process is being performed.

[0060] In the first or second modified example, the ECU 6 may execute the fifth command in response to the key switch 8 being switched to start during the balance process.

[0061] [Fourth variation] Next, a fourth modified example of the control device 100's processing will be described in detail with reference to Figures 1 and 8. Figure 8 is a diagram showing an example of the display screen of the display 9 shown in Figure 1.

[0062] During the balance process, the ECU 6 displays a screen 91 on the display 9, as shown in Figure 8. The screen 91 is related to the balance process. Specifically, the screen 91 includes at least one of a first string 911 and a second string 912, and a third string 913. The first string 911 is a string indicating that the control device 100 will stop after the balance process is completed. The second string 912 is a string indicating that the work machine 200 can be switched to start by the key switch 8 during the balance process. The third string 913 is a string indicating that the balance process is being performed.

[0063] According to the fourth modified example, the operator of the work machine 200 can easily understand the current status of the work machine 200 by viewing at least one of the first string 911 and the second string 912 and the third string 913 on the screen 91.

[0064] [Fifth variation] Next, a fifth modified example of the control device 100 will be described in detail with reference to Figures 1 and 9. Figure 9 is a block diagram of a work machine 200 equipped with the control device 100 according to the fifth modified example. As shown in Figure 9, the control device 100 of the fifth modified example differs from the control device 100 of the embodiment in that it is equipped with a light-emitting element 92 instead of a display 9. The light-emitting element 92 is another example of a display unit.

[0065] The light-emitting element 92 emits light while the balancing process is being performed under the control of the ECU 6. The emitted light indicates that the balancing process is in progress. Furthermore, the light intensity of the emitted light is greater than the light intensity of the display 9. As a result, the operator of the work machine 200 can understand the current status of the work machine 200 remotely.

[0066] Embodiments of the present disclosure have been described above with reference to the drawings. However, the present disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its essence. Furthermore, the multiple components disclosed in the above embodiments can be modified as appropriate. For example, some components from all the components shown in one embodiment may be added to the components of another embodiment, or some components from all the components shown in one embodiment may be removed from the embodiment.

[0067] Furthermore, the drawings schematically show each component in order to facilitate understanding of this disclosure, and the thickness, length, number, spacing, etc. of each component shown may differ from the actual dimensions due to the convenience of drawing creation. Also, the configuration of each component shown in the above embodiments is merely an example and is not particularly limiting, and it goes without saying that various modifications are possible within the scope that does not substantially deviate from the effects of this disclosure.

[0068] (1) In this embodiment, since the electric motor 201 is a three-phase AC motor, the battery pack 2 supplies AC power to the electric motor 201 as a load via the inverter 3. However, it is not limited to this, and if the electric motor 201 is a DC motor, the battery pack 2 can supply DC voltage to the electric motor 201 via a DC-DC converter or directly.

[0069] (2) In the embodiment, the characteristic value was the difference between the maximum and minimum values ​​for all cell voltages. However, it is not limited to this, and the characteristic value may also be the variance or standard deviation of all cell voltages. Alternatively, a minimum cell voltage (i.e., four cell voltages in the embodiment) may be selected for each battery module 21. The difference between the maximum and minimum values ​​for the selected cell voltages may be derived as the characteristic value.

[0070] (3) In this embodiment, the control device 100 controlled the electric motor 201 of the work machine 200. However, it is not limited to this, and the control device 100 may control, for example, the motor of an electric vehicle. In addition, the control device 100 can be applied to electrical equipment or electronic equipment equipped with a battery pack 2.

[0071] (4) In the embodiment, the control device 100 was applied to a work machine 200 operated by a user. However, the control device 100 is not limited to this and may be applied to a work machine 200 that can be remotely operated. In this case, the control device 100 includes a remote controller for switching between starting and stopping instead of the key switch 8. Alternatively, the control device 100 may be applied to an automatically operated work machine 200. In this case, the control device 100 uses the ECU 6 to switch between starting and stopping the work machine 200 instead of the key switch 8.

[0072] This application discloses the following notes. These notes are not intended to limit the present invention.

[0073] (Note 1) It has multiple battery cells and a first energy storage unit that supplies power to the load, A switching unit for switching between starting and stopping the load, A second energy storage unit that can be charged and discharged, A power supply unit capable of supplying power from the first power storage unit to the second power storage unit, A characteristic value derivation unit that derives characteristic values ​​indicating the voltage variation of each of the plurality of battery cells, A balancing processing unit capable of performing a balancing process to reduce the aforementioned voltage variation, A control unit that receives power from the second energy storage unit and Equipped with, A control device in which, when the switching unit is switched to stop and the characteristic value derived by the characteristic value derivation unit is greater than or equal to a first threshold, the control unit transmits a first command to the power supply unit to instruct the supply of power from the first energy storage unit to the second energy storage unit, and transmits a second command to the balance processing unit to instruct the execution of the balance processing.

[0074] (Note 2) The control unit, during the execution of the balancing process, When the characteristic value derived by the characteristic value derivation unit reaches a second threshold that is smaller than the first threshold, the transmission of the first command is stopped. When the characteristic value derived by the characteristic value derivation unit reaches a third threshold that is smaller than the second threshold, the transmission of the second command is stopped. The control device described in Appendix 1, which transmits the first command to the power supply unit when the voltage of the second energy storage unit reaches a fourth threshold.

[0075] (Note 3) The control device according to Appendix 1 or Appendix 2, wherein, during the execution of the balancing process, when the characteristic value derived by the characteristic value derivation unit reaches a fifth threshold that is smaller than the first threshold, the control unit stops transmitting the second command to the balancing unit and transmits a fourth command to instruct the interruption of the power supply path from the second energy storage unit to the control unit.

[0076] (Note 4) The control device according to any one of the appendices 1 to 3, wherein the characteristic value is the difference between the maximum and minimum values ​​of the individual voltages of the plurality of battery cells.

[0077] (Note 5) The control device according to any one of the appendices 1 to 4, wherein the control unit transmits a fifth command to the load to start the load when the switching unit is switched to start during the execution of the balancing process.

[0078] (Note 6) The control device according to any one of the appendices 1 to 5, further comprising a display unit that displays a screen related to the balancing process during the execution of the balancing process.

[0079] (Note 7) The control unit generates a third image including at least one of the first string and the second string, and the third string. The first string indicates that the control device will stop after the completion of the balancing process. The second string indicates that the switching unit can switch to start during the execution of the balancing process, The third string indicates that the balancing process is being performed, and is a control device according to any of the appendices 1 to 6.

[0080] (Note 8) Further equipped with light-emitting elements, The control unit is the control device according to any one of Appendix 1 to Appendix 7, wherein the control unit lights up the light-emitting element when the balance processing unit is performing the balance processing. [Industrial applicability]

[0081] The present invention relates to a control device and has industrial applicability. [Explanation of symbols]

[0082] 100 Control device 1 rectifier 2 Battery Packs 21 Battery Modules 211 CMU 212 battery cells 213 Cell balancing circuit 214 Voltage detection circuit 22 BMU 3 Inverter 4 Converters 5 Low-voltage battery 6 ECU 7 Self-holding circuit 8 Key Switches 9 displays 91 screens 92 Light-emitting elements 101 Power supply route 200 working machines

Claims

1. It has multiple battery cells and a first energy storage unit that supplies power to the load, A switching unit for switching between starting and stopping the load, A second energy storage unit that can be charged and discharged, A power supply unit capable of supplying power from the first power storage unit to the second power storage unit, A characteristic value derivation unit that derives characteristic values ​​indicating the voltage variation of each of the plurality of battery cells, A balancing processing unit capable of performing a balancing process to reduce the aforementioned voltage variation, A control unit that receives power from the second energy storage unit and Equipped with, A control device in which, when the switching unit is switched to stop and the characteristic value derived by the characteristic value derivation unit is greater than or equal to a first threshold, the control unit transmits a first command to the power supply unit to instruct the supply of power from the first energy storage unit to the second energy storage unit, and transmits a second command to the balance processing unit to instruct the execution of the balance processing.

2. The control unit, during the execution of the balancing process, When the characteristic value derived by the characteristic value derivation unit reaches a second threshold that is smaller than the first threshold, the transmission of the first command is stopped. When the characteristic value derived by the characteristic value derivation unit reaches a third threshold that is smaller than the second threshold, the transmission of the second command is stopped. The control device according to claim 1, wherein when the voltage of the second energy storage unit reaches a fourth threshold, the first command is transmitted to the power supply unit.

3. The control device according to claim 1, wherein, during the execution of the balancing process, when the characteristic value derived by the characteristic value derivation unit reaches a fifth threshold that is smaller than the first threshold, the control unit stops transmitting the second command to the balancing unit and transmits a fourth command to a self-holding circuit that maintains the operation of a relay provided on the power supply path to interrupt the power supply path from the second energy storage unit to the control unit.

4. The control device according to any one of claims 1 to 3, wherein the characteristic value is the difference between the maximum and minimum values ​​of the individual voltages of the plurality of battery cells.

5. The control device according to any one of claims 1 to 3, wherein the control unit transmits a fifth command to the load to start the load when the switching unit is switched to start during the execution of the balancing process.

6. The control device according to any one of claims 1 to 3, further comprising a display unit that displays a screen related to the balancing process during the execution of the balancing process.

7. The control unit generates a third image including at least one of the first string and the second string, and the third string. The first string indicates that the control device will stop after the completion of the balancing process. The second string indicates that the switching unit can switch to start during the execution of the balancing process. The control device according to any one of claims 1 to 3, wherein the third string indicates that the balancing process is being performed.

8. Further equipped with light-emitting elements, The control device according to any one of claims 1 to 3, wherein the control unit lights up the light-emitting element when the balance processing unit is performing the balance processing.

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