control device

Abstract

To provide a control device capable of preventing excessive discharge of a battery cell in 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 characteristic value derivation part derives a characteristic value indicating variations in respective voltages of the plurality of battery cells. A balance processing part can execute balance processing of reducing the variations in the voltages. When 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 execute the balance processing to the balance processing part. The balance processing part determines a target voltage higher than the lowest voltage by a predetermined voltage among the respective voltages of the plurality of battery cells, in response to reception of the first command. The balance processing part further executes the balance processing based on the determined target voltage.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] A cell capacity adjustment device according to the background art is provided in an electric device equipped with a battery module in which a plurality of battery cells are connected in series. When the operation of the electric device is paused, the cell capacity adjustment device executes a balancing process. In the balancing process, after the voltages of the battery cells included in the battery module are acquired, the lowest voltage among the total voltages is set as the target voltage. The cell capacity adjustment device executes the balancing process so that the voltages of all the battery cells are aligned with the target voltage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the background art, there is a risk of excessively discharging the battery cells until the voltage falls below the target voltage (i.e., the lowest voltage).

[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 preventing excessive discharge of battery cells in a balancing process.

Means for Solving the Problems

[0006] The control device according to the present invention comprises a first energy storage 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 characteristic value derivation unit derives characteristic values ​​that indicate the voltage variation of each of the plurality of battery cells. The balance processing unit is capable of performing a balance processing to reduce the voltage variation. When 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 balance processing unit to instruct it to perform the balance processing. In response to receiving the first command, the balance processing unit determines a target voltage that is a predetermined voltage higher than the lowest voltage among the voltages of the plurality of battery cells. The balance processing unit further performs the balance processing based on the determined target voltage. [Effects of the Invention]

[0007] According to the present invention, excessive discharge of battery cells can be prevented during the balancing process. [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 100. [Figure 4] This figure shows the details of the balancing process as shown in Figure 3. [Figure 5] This figure shows an example of the display screen of the display 9 shown in Figure 1. [Figure 6A] Figure 1 is a flowchart showing the first part of a modified example of the processing of the control device 100. [Figure 6B] This flowchart shows a second modified example of the processing of the control device 100 shown in Figure 1. [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] The rectifier 1 can receive the supply of an 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. The rectifier 1 is further electrically connected to a battery pack 2 and an inverter 3. When the operation mode of the working machine 200 is the first mode, the rectifier 1 converts the AC voltage into a DC voltage and supplies the converted DC voltage to the battery pack 2. The rectifier 1 further converts the AC voltage into a DC voltage and supplies the converted DC voltage to the inverter 3 when the operation mode is the second mode. The rectifier 1 further cuts off the power supply path from the rectifier 1 to the battery pack 2 and the inverter 3 when the operation mode is the third mode. As a result, the DC voltage is supplied to the inverter 3 by the battery pack 2. The first mode, the second mode, and the third mode are selectively switched by a mode switch (not shown) provided in the working machine 200.

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

[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 the 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 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. Typically, the low-voltage battery 5 is a lithium-ion battery or a lead-acid battery.

[0019] The ECU 6 operates by 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. 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 working machine 200.

[0020] The self-holding circuit 7 is a circuit that holds the operation of a relay provided on the power supply path 101. When a start signal from the key switch 8 is input, the self-holding circuit 7 turns on the relay. As a result, the ECU 6 and the low-voltage battery 5 are electrically connected by the power supply path 101. That is, the power supply from the low-voltage battery 5 to the ECU 6 is started. 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 the operator. In other words, the key switch 8 switches the electric motor 201, which is the load, on and off. When the key switch 8 is switched to start, it sends 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 sends a stop signal to the ECU 6. When the key switch 8 is switched to stop, the engine stops.

[0022] 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 monitors and controls the status 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 acquires the cell voltage from each voltage detection circuit 214 and from each CMU214. The BMU22 functions as an example of a characteristic value derivation unit and derives a characteristic value that indicates the magnitude of variation in 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. Therefore, the characteristic value can be derived with a simple calculation.

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

[0031] As shown in Figure 3, when the key switch 8 is switched to start, the control device 100 starts processing and the work machine 200 starts.

[0032] In step S101, the ECU 6 periodically sends a request to the BMU 22 to transmit characteristic values.

[0033] In step S102, in response to receiving a transmission request, the BMU22 acquires the cell voltage from each voltage detection circuit 214 via the CMU211 of the same battery module 21. The BMU22 derives characteristic values ​​based on the acquired cell voltages. The BMU22 transmits the derived characteristic values ​​to the ECU6.

[0034] 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 predetermined reference value indicating whether the variation in cell voltage is large or small. If the ECU6 determines that the value is not greater than or equal to the first threshold (No in step S103), it executes step S106. On the other hand, if the ECU6 determines that the value is greater than or equal to the first threshold (Yes in step S103), it executes step S104.

[0035] In step S104, the ECU6 sends a first command to the BMU22. The first command is a command to instruct the BMU22 to perform the balancing process.

[0036] In step S105, in response to receiving the first command, the BMU22 identifies the lowest voltage among the multiple cell voltages acquired in step S102. The BMU22 then determines a target voltage higher than the identified lowest voltage.

[0037] In step S105, the BMU22 further instructs each CMU211 to perform a balance process. The BMU22 and each CMU211 perform a balance process based on the determined target voltage, as an example of a balance processing unit. As a result of the balance process based on the target voltage, the variation in the cell voltages of the multiple battery cells 212 in each battery module 21 is reduced. Since the target voltage is set to a value higher than the minimum voltage, all battery cells 212 do not fall below the minimum voltage due to discharge. In other words, excessive discharge of battery cells can be prevented during the balance process.

[0038] The details of the balancing process are as follows. First, each CMU 211 identifies the target battery cell 212 from the four battery cells 212 in the same battery module 21. The target battery cell 212 is the battery cell 212 that has a cell voltage higher than the target voltage. Each CMU 211 turns on the switching element 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 from the discharge resistor included in the corresponding cell balancing circuit 213. Each CMU 211 turns off the switching element of each corresponding cell balancing circuit 213 in response to the cell voltage detected by the voltage detection circuit 214 connected in parallel to the target battery cell 212 reaching the target voltage. Each CMU 211 reduces the cell voltage of all target battery cells 212 to a voltage slightly higher than the target voltage.

[0039] In the balancing process, the ECU6 periodically executes step S105A. In step S105A, the ECU6 receives characteristic values ​​from the BMU22 in the same manner as in steps S101 and S102. The ECU6 further determines whether the received characteristic values ​​are less than or equal to a second threshold. The second threshold is a characteristic value that is smaller than the first threshold and indicates the variation in the cell voltages of the multiple battery cells 212 relative to the target voltage. The second threshold is predetermined. If the ECU6 determines that the values ​​are not less than or equal to the second threshold (No in step S105A), it executes step S105A. On the other hand, if the ECU6 determines that the values ​​are less than or equal to the second threshold (Yes in step S105A), it terminates the balancing process and waits to execute step S101 until the transmission cycle for the next transmission request begins.

[0040] In step S106, the ECU 6 determines whether or not it has received a stop signal from the key switch 8. If the ECU 6 determines that it has not received a stop signal (No in step S106), it waits to execute step S101 until the transmission cycle for the next transmission request begins. On the other hand, if the ECU 6 determines that it has received a stop signal (Yes in step S106), it executes step S107.

[0041] Steps S107 to S109 are the same process as steps S101 to S103. If ECU6 determines that the value is not above the first threshold (No in step S109), it executes step S110. On the other hand, if ECU6 determines that the value is above the first threshold (Yes in step S109), it executes step S111.

[0042] In step S110, since the ECU 6 does not need to perform the balancing process, it 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. That is, the process in Figure 3 is completed.

[0043] In step S111, the ECU 6 sends a first command to the BMU 22. Specifically, the ECU 6 sends the first command to the BMU 22 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. Therefore, the balancing process is performed after the work machine 200 is stopped. As a result, power is stably supplied from the battery pack 2 when the work machine 200 is operated next.

[0044] In step S111, the ECU 6 further sends a second command to the converter 4. The second command is a command to instruct the battery pack 2 to supply power to the low-voltage battery 5.

[0045] In step S112, the converter 4, upon receiving the second command, supplies a DC voltage from the battery pack 2 to the low-voltage battery 5. As a result, the low-voltage battery 5 is charged. The ECU 6 sends the second command to the converter 4 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. Therefore, the ECU 6 is continuously supplied with DC voltage from the low-voltage battery 5 without interruption, and the balancing process is performed stably.

[0046] In step S113, in response to receiving the first command, the BMU22 instructs each CMU211 to perform the balancing process, similar to step S105. As a result, the same balancing process as in step S105 is performed.

[0047] During the balancing process, the ECU6 periodically executes step S113A. In step S113A, the ECU6 receives characteristic values ​​from the BMU22 in the same manner as in steps S101 and S102. The ECU6 further determines whether the received characteristic values ​​are below the second threshold. If the ECU6 determines that the values ​​are not below the second threshold (No in step S113A), it executes step S113A. On the other hand, if the ECU6 determines that the values ​​are below the second threshold (Yes in step S113A), it terminates the balancing process and executes step S110.

[0048] Next, the details of the balancing process will be explained with reference to Figures 1 to 4. Figure 4 is a diagram showing the details of the balancing process shown in Figure 3. Figure 4 shows the cell voltage distributions A to D. Each of the distributions A to D shows four battery cells A1 to D1 as examples of multiple battery cells 212.

[0049] Cell voltage distribution A shows the cell voltages of battery cells A1 to D1 at the time of transmission of the first command (see step S111 in Figure 3). In cell voltage distribution A, the cell voltage of battery cell A1 is exemplified as 2.54[V]. The cell voltages of battery cells B1 to D1 are as shown in the figure.

[0050] Cell voltage distribution B shows the cell voltages of battery cells A1 to D1 at the time the target voltage is determined (see step S113 in Figure 3). In cell voltage distribution B, the cell voltages of battery cells A1 to D1 are the same as when the first command is transmitted. Cell voltage distribution B shows a target voltage of 2.52[V], which is the lowest cell voltage among battery cells A1 to D1 (2.50[V]) plus a predetermined voltage of 20[mV].

[0051] Cell voltage distribution C shows the cell voltages of battery cells A1 to D1 during the balancing process (see step S113 in Figure 3). As shown in cell voltage distribution C, battery cells A1 and C1, which have cell voltages higher than the target voltage among battery cells A1 to D1, discharge. Therefore, the cell voltages of battery cells A1 and C1 approach the target voltage compared to before the start of the balancing process.

[0052] As shown in cell voltage distribution D, during the balancing process, the low-voltage battery 5 is charged by the DC voltage from battery pack 2. As a result, the voltage of each battery cell A1 to D1 decreases. However, since the target voltage is set to a value higher than the lowest cell voltage, all battery cells 212 do not fall below the lowest voltage due to discharge.

[0053] Next, with reference to Figure 5, step S113 (balancing process) in Figure 3 will be explained in more detail. Figure 5 shows the notification image 93 displayed on the display 9 shown in Figure 1. The notification image 93 is an example of an image.

[0054] During the execution of step S113 (balancing process), the ECU 6 displays image data showing a notification image 93, as shown in Figure 5, on the display 9. The notification image 93 is an image related to the balancing process and includes at least one of a first string 931 and a second string 932, and a third string 933. The first string 931 is a string indicating that the control device 100 will stop after the balancing process is completed. The second string 932 is a string indicating that the work machine 200 can be switched to start by the key switch 8 while the balancing process is being executed. The third string 933 is a string indicating that the balancing process is being executed.

[0055] According to the second modification, the operator of the work machine 200 can understand that a balancing process is being performed on the stopped work machine 200 by viewing the notification image 93. In addition, the operator can visually obtain various information by viewing at least one of the first string 931 and the second string 932, and the third string 933.

[0056] [Differentiation] Next, with reference to Figures 1, 2, 6A, and 6B, modified versions of the control device 100's processing will be described in detail. Figures 6A and 6B are flowcharts showing the first and second parts, respectively, of the modified versions of the control device 100's processing shown in Figure 1.

[0057] As shown in Figures 6A and 6B, when the control program is running, the control device 100 executes steps S201 to S219, S205A, S214A, and S219A. Of these, steps S201 to S210 and S205A are the same as steps S101 to S110 and S105A in Figure 3, so their respective explanations will be omitted.

[0058] Step S211 is executed if it is determined in step S209 that the characteristic value is equal to or greater than the first threshold. In step S211, the ECU 6 determines whether the current voltage value of the low-voltage battery 5 has reached the third threshold. The third threshold is a reference value that indicates whether or not to supply power to the low-voltage battery 5. If it is determined that the voltage value is not equal to or greater than the third threshold (No in step S211), steps S212 to S214 and S214A are executed. Steps S212 to S214 are the same as steps S111 to S113 and S113A in Figure 3, so their respective explanations are omitted. On the other hand, if it is determined that the voltage value is equal to or greater than the third threshold (Yes in step S211), step S215 is executed.

[0059] In step S215, the ECU 6 sends a first command to the BMU 22. However, no second command is sent in step S215. Specifically, if the characteristic value derived by the BMU 22 is greater than or equal to the first threshold, and the current voltage value of the low-voltage battery 5 is greater than or equal to the third threshold, the DC voltage of the battery pack 2 is not supplied to the low-voltage battery 5. Therefore, the voltage of each cell in the battery pack 2 stabilizes during the balancing process.

[0060] In step S216, in response to receiving the first command, the BMU22 instructs each CMU211 to perform the balancing process, similar to step S205. As a result, the same balancing process as in step S205 is performed.

[0061] Next, in step S217, the ECU 6 determines, similar to step S211, whether the current voltage value of the low-voltage battery 5 has reached the third threshold. If it determines that the voltage value is equal to or greater than the third threshold (Yes in step S217), step S219A is executed. On the other hand, if it determines that the voltage value is not equal to or greater than the third threshold (No in step S217), step S218 is executed.

[0062] In step S218, the ECU 6 sends a second command to the converter 4. Specifically, the ECU 6 sends the second command if it determines that the voltage value of the low-voltage battery 5 is equal to or greater than the third threshold during the balancing process.

[0063] In step S219, the converter 4, in response to receiving the second command, supplies a DC voltage from the battery pack 2 to the low-voltage battery 5. As a result, the balancing process is performed stably without interruption due to power shortage.

[0064] If the result in step S217 is Yes, or after step S219 is executed, step S219A is executed. Step S219A is the same process as step S105A. If ECU6 determines that it is not below the second threshold (No in step S219A), it executes step S217. On the other hand, if ECU6 determines that it is below the second threshold (Yes in step S219A), it executes step S210.

[0065] 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.

[0066] 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.

[0067] (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.

[0068] (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.

[0069] (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.

[0070] (4) In one embodiment, the control device 100 was applied to a work machine 200 operated by an operator. 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.

[0071] (5) In this embodiment, the control device 100 was equipped with a display 9. However, the control device 100 is not required to be equipped with a display 9 if the work machine 200 can be remotely operated by a remote controller or monitored by a cloud computer. Specifically, the control device 100 can transmit status image data to the remote controller or cloud computer via a wireless communication interface.

[0072] (6) In the embodiment, as shown in Figure 3, Figures 6A and 6B, the balancing process could be performed before and after receiving the stop signal of the key switch 8. However, the control program is not limited to this, and it is sufficient if the balancing process is performed at least after receiving the stop signal.

[0073] (7) In the embodiment, the target voltage was a voltage higher than the minimum voltage. However, the target voltage is not limited to this, and is a voltage that is a predetermined voltage higher than the minimum voltage. The predetermined voltage is a fixed value that is set in advance. When it is a fixed value, the target voltage can be easily determined, thus reducing the processing load on the ECU6. Alternatively, the target voltage may be a value between the average value of all cell voltages and the minimum voltage (i.e., a variable value). In this case, the target voltage is reliably kept low, so the variation in cell voltage is relatively reduced.

[0074] This application discloses the following notes. These notes are not intended to limit the present invention.

[0075] (Note 1) It has multiple battery cells and a first energy storage unit that supplies power to the load, 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, Control unit and Equipped with, The control unit transmits a first command to the balance processing unit to instruct the execution of the balance processing when the characteristic value derived by the characteristic value derivation unit is equal to or greater than a first threshold. The balance processing unit is a control device that, in response to receiving the first command, determines a target voltage higher than the lowest voltage among the voltages of the plurality of battery cells, and performs the balance processing based on the determined target voltage.

[0076] (Note 2) The control device according to Appendix 1, wherein the balance processing unit discharges battery cells among the plurality of battery cells that have a voltage higher than the target voltage to bring them to the target voltage, thereby reducing the voltage variation.

[0077] (Note 3) If the characteristic values ​​of the plurality of battery cells are below the second threshold, the balancing process is completed. The control device according to Appendix 1 or Appendix 2, wherein the second threshold is smaller than the first threshold and larger than a characteristic value indicating the variation of the target voltage with respect to the voltages of the plurality of battery cells.

[0078] (Note 4) The control device according to Appendix 1 to Appendix 3, wherein the target voltage is a value between the average value of the voltages of each of the plurality of battery cells and the minimum voltage.

[0079] (Note 5) 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 and Furthermore, The control device according to any one of the appendices 1 to 4, wherein the control unit transmits a second command to the power supply unit instructing the supply of power from the first energy storage unit to the second energy storage unit when the characteristic value derived by the characteristic value derivation unit is equal to or greater than the first threshold.

[0080] (Note 6) The control unit, If the characteristic value derived by the characteristic value derivation unit is equal to or greater than the first threshold, and the voltage of the second energy storage unit is equal to or greater than the third threshold, the second command is not transmitted to the power supply unit. The control device according to Appendix 5, which transmits the second command to the power supply unit when the voltage of the second energy storage unit is less than the third threshold during the execution of the balancing process.

[0081] (Note 7) The system further includes a switching unit for switching between starting and stopping the aforementioned load, The control device according to any one of the appendices 1 to 6, wherein the control unit transmits the first command to the balance processing 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.

[0082] (Note 8) The control device according to Appendix 7, further comprising a display unit that displays an image related to the balancing process during the execution of the balancing process.

[0083] (Note 9) The control unit generates the image which includes 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, as described in Appendix 8, and is the control device. [Industrial applicability]

[0084] The present invention relates to a control device and has industrial applicability. [Explanation of Symbols]

[0085] 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 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 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, Control unit and Equipped with, The control unit transmits a first command to the balance processing unit to instruct it to execute the balance processing when the characteristic value derived by the characteristic value derivation unit is equal to or greater than a first threshold. The balance processing unit, upon receiving the first command, determines a target voltage higher than the lowest voltage among the voltages of the plurality of battery cells, and performs the balance processing based on the determined target voltage. If the characteristic values ​​of the plurality of battery cells are below the second threshold, the balancing process is completed. A control device wherein the second threshold is smaller than the first threshold and larger than a characteristic value indicating the variation of the target voltage with respect to the voltages of the plurality of battery cells.

2. A first energy storage unit having a plurality of battery cells and supplying power to a load, 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, Control unit and Equipped with, The control unit transmits a first command to the balance processing unit to instruct it to execute the balance processing when the characteristic value derived by the characteristic value derivation unit is equal to or greater than a first threshold. The balance processing unit, upon receiving the first command, determines a target voltage higher than the lowest voltage among the voltages of the plurality of battery cells, and performs the balance processing based on the determined target voltage. 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 and Furthermore, The control unit transmits a second command to the power supply unit instructing the supply of power from the first energy storage unit to the second energy storage unit when the characteristic value derived by the characteristic value derivation unit is equal to or greater than the first threshold.

3. A first energy storage unit having a plurality of battery cells and supplying power to a load, 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, Control unit and Equipped with, The control unit transmits a first command to the balance processing unit to instruct it to execute the balance processing when the characteristic value derived by the characteristic value derivation unit is equal to or greater than a first threshold. The balance processing unit, upon receiving the first command, determines a target voltage higher than the lowest voltage among the voltages of the plurality of battery cells, and performs the balance processing based on the determined target voltage. The system further includes a switching unit for switching between starting and stopping the aforementioned load, The control unit transmits the first command to the balance processing 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. A control device further comprising a display unit that displays an image related to the balancing process during the execution of the balancing process, The control unit generates the image which includes 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 a control device that is performing the balancing process.

4. The control device according to any one of claims 1 to 3, wherein the balance processing unit discharges the battery cells among the plurality of battery cells that have a voltage higher than the target voltage to the target voltage, thereby reducing the voltage variation.

5. The control device according to any one of claims 1 to 3, wherein the target voltage is a value between the average value of the voltages of each of the plurality of battery cells and the minimum voltage.

6. The control unit is If the characteristic value derived by the characteristic value derivation unit is equal to or greater than the first threshold, and the voltage of the second energy storage unit is equal to or greater than the third threshold, the second command is not transmitted to the power supply unit. The control device according to claim 2, wherein if the voltage of the second energy storage unit is less than the third threshold during the execution of the balancing process, the control device transmits the second command to the power supply unit.

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