Semiconductor device, cell balance control method, and battery pack

Abstract

To more appropriately perform cell balancing.SOLUTION: The charging rate of each battery cell at each point in time is estimated on the basis of the voltage of each battery cell connected in series at each point in time, the integrated value of the current flowing through the multiple battery cells during the period between each point in time is calculated, the maximum capacity of each battery cell is estimated on the basis of the charging rate of each battery cell at each point in time and the integrated value, a reference battery cell is determined on the basis of the maximum capacity of each battery cell and the charging rate of each battery cell, and battery cells other than the reference battery cell are discharged.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor device, a cell balancing control method, and a battery pack. [Background technology]

[0002] It has been known that imbalances in capacity between cells (cell imbalances) can occur due to manufacturing variations in battery cells and individual differences in deterioration over long periods of use. When charging or discharging in such a state, some cells may be overcharged or overdischarged. Furthermore, if some cells are overcharged or overdischarged, the protection function of those cells may stop charging or discharging. In this case, the original performance of the remaining cells may not be fully realized, even though they remain usable.

[0003] In a battery pack composed of multiple cells, a technique for equalizing the voltages of the cells (cell balancing) is known to prevent over-discharge and over-charge caused by variations in remaining capacity among the cells (see, for example, Patent Document 1). Patent Document 1 discloses a technique for performing cell balancing control using a flying capacitor. Another known method for performing cell balancing control is to periodically measure the cell voltages, discharge the cells when the voltage difference between the cells exceeds a cell balancing start threshold, and terminate the cell discharge when the voltage difference between the cells falls below a cell balancing end threshold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-058013 Summary of the Invention [Problem to be solved by the invention]

[0005] The voltage of a cell changes depending on aging, operating temperature, and discharge current. Therefore, even if cell balancing is performed to match the cell voltage, the capacity of the cells does not necessarily match. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0006] In one embodiment of the present disclosure, a battery system includes a voltage measurement circuit that measures the voltage of each of a first battery cell and a second battery cell that are connected in series, a current measurement circuit that measures the current flowing through the first battery cell and the second battery cell, and a control unit that controls discharging of at least one of the first battery cell and the second battery cell, wherein the control unit estimates a charging rate of each of the first battery cell and the second battery cell at a first point in time based on the voltage of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at the first point in time, and estimates a charging rate of each of the first battery cell and the second battery cell at the second point in time based on the voltage of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at a second point in time different from the first point in time, and a maximum capacity of the second battery cell based on the charging rate of the second battery cell at the first time point, the charging rate of the first battery cell at the second time point, and the integrated value; a maximum capacity of the second battery cell based on the charging rate of the second battery cell at the first time point, the charging rate of the second battery cell at the second time point, and the integrated value; a reference battery cell is determined from the first battery cell and the second battery cell based on the maximum capacity of the first battery cell, the charging rate of the first battery cell, the maximum capacity of the second battery cell, and the charging rate of the second battery cell; and a battery cell of the first battery cell and the second battery cell other than the reference battery cell is discharged.

[0007] In one embodiment of the present disclosure, a semiconductor device estimates a charging rate of each of the first battery cell and the second battery cell at a first time point based on the voltages of the first battery cell and the second battery cell measured at a first time point by a voltage measurement circuit that measures the voltages of the first battery cell and the second battery cell connected in series, estimates a charging rate of each of the first battery cell and the second battery cell at the first time point based on the voltages of the first battery cell and the second battery cell measured at a second time point by the voltage measurement circuit, and estimates a charging rate of each of the first battery cell and the second battery cell at the second time point based on the voltages of the first battery cell and the second battery cell measured at the second time point by a current measurement circuit that measures a current flowing through the first battery cell and the second battery cell. a cell balance control method for calculating an integrated value of a current flowing through two battery cells, estimating a maximum capacity of the first battery cell based on the charging rate of the first battery cell at the first time point, the charging rate of the first battery cell at the second time point, and the integrated value, estimating a maximum capacity of the second battery cell based on the charging rate of the second battery cell at the first time point, the charging rate of the second battery cell at the second time point, and the integrated value, determining a reference battery cell from the first battery cell and the second battery cell based on the maximum capacity of the first battery cell, the charging rate of the first battery cell, the maximum capacity of the second battery cell, and the charging rate of the second battery cell, and discharging battery cells from the first battery cell and the second battery cell other than the reference battery cell.

[0008] In one embodiment of the present disclosure, a battery includes a first battery cell and a second battery cell connected in series, a voltage measurement circuit that measures the voltages of the first battery cell and the second battery cell, a current measurement circuit that measures the current flowing through the first battery cell and the second battery cell, and a control unit that controls discharging of at least one of the first battery cell and the second battery cell, wherein the control unit estimates a charging rate of the first battery cell and the second battery cell at a first point in time based on the voltages of the first battery cell and the second battery cell measured by the voltage measurement circuit at the first point in time, and calculates a charging rate of the first battery cell and the second battery cell at the second point in time based on the voltages of the first battery cell and the second battery cell measured by the voltage measurement circuit at a second point in time different from the first point in time. a maximum capacity of the first battery cell based on the charging rate of the first battery cell at the first time point, the charging rate of the first battery cell at the second time point, and the integrated value; a maximum capacity of the second battery cell based on the charging rate of the second battery cell at the first time point, the charging rate of the second battery cell at the second time point, and the integrated value; a reference battery cell is determined from the first battery cell and the second battery cell based on the maximum capacity of the first battery cell, the charging rate of the first battery cell, the maximum capacity of the second battery cell, and the charging rate of the second battery cell; and battery cells of the first battery cell and the second battery cell other than the reference battery cell are discharged. [Effects of the Invention]

[0009] According to one aspect, cell balancing can be performed more appropriately. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of a device according to an embodiment. [Figure 2] 10 is a flowchart illustrating an example of processing by a control unit according to the embodiment. [Figure 3] FIG. 4 is a diagram showing an example of data recorded in an SOC-OCV table according to the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of the relationship between the capacity and voltage of each battery cell according to the embodiment. [Figure 5] 10 is a timing chart showing an example of timing of cell balancing processing according to the embodiment; [Figure 6] 10 is a timing chart showing an example of timing of cell balancing processing according to the embodiment; [Figure 7] FIG. 2 is a diagram illustrating an example of a configuration of a control unit according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The principles of the present disclosure will be described with reference to some exemplary embodiments. It should be understood that these embodiments are set forth for illustrative purposes only, to aid those skilled in the art in understanding and practicing the present disclosure, without implying any limitation on the scope of the disclosure. The disclosure described herein may be implemented in various ways other than those described below.

[0012] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. <Configuration> The configuration of a device 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the configuration of a device 1 according to an embodiment. The device 1 may be, for example, a personal computer, a server, a home appliance, a factory appliance, or a vehicle. Examples of vehicles in the present disclosure may include, for example, an electric vehicle (EV), a hybrid electric vehicle (HEV), an electric motorcycle, an electrically assisted bicycle, and an electric kick scooter.

[0014] 1, the device 1 includes a battery pack 10 and a main body 20. The main body 20 is a main body portion of the device 1. The battery pack 10 may be housed in a housing of the main body 20.

[0015] The battery pack 10 includes battery cells C1 to C n (n is an integer of 2 or more), and a battery management IC (Integrated Circuit) 11 (an example of a "semiconductor device"). n are connected in series, with the positive side electrically connected to the main body 20 at connection point P1 and the negative side electrically connected to the main body 20 at connection point P2. They are also electrically connected to the main body 20 at connection point P3 for communication to notify the battery state, etc.

[0016] The battery management IC 11 includes a cell balance unit 111, a selection circuit 112, a voltage measurement circuit 113, a current measurement circuit 114, and a control unit 115. The cell balance unit 111 includes resistors R1 to R n , switches S1 to S n and switch control circuits SC1 to SC2 that control the switches. n The combination of each battery cell C1 to C n Each has.

[0017] The selection circuit 112 selects the battery cells C1 to C n This is a circuit that electrically connects only one battery cell designated by the control unit 115 to the voltage measurement circuit 113 out of the above.

[0018] The voltage measurement circuit 113 measures the voltage of the battery cells C1 to C2 connected in series. n In the example of FIG. 1, the voltage measurement circuit 113 measures the voltages of the battery cells C1 to C n The selection circuit 112 measures the voltage of the battery cell selected from the above.

[0019] The current measurement circuit 114 measures the current of the battery cells C1 to C2 connected in series. nIn the example of FIG. 1, the current measuring circuit 114 measures the current flowing through the battery cells C1 to C n Based on the magnitude of the voltage drop across the sense resistor Rs provided on the electrical circuit to which the battery cells C1 to C n The control unit 115 measures the current flowing through the battery cells C1 to C n The discharge of at least one battery cell is controlled.

[0020] <Processing of the control unit 115> Next, an example of the processing of the control unit 115 according to the embodiment will be described with reference to Figs. 2 to 6. Fig. 2 is a flowchart showing an example of the processing of the control unit 115 according to the embodiment. Fig. 3 is a diagram showing an example of data recorded in an SOC-OCV table according to the embodiment. Fig. 4 is a diagram showing an example of the relationship between the capacity and voltage of each battery cell according to the embodiment. Figs. 5 and 6 are timing charts showing an example of the timing of the cell balancing processing according to the embodiment. Note that the processing of Fig. 2 may be executed periodically, for example, in a no-load state (a state in which no load is connected to the battery cell and no current flows in or out of the battery cell).

[0021] In step S101, the control unit 115 calculates the voltages of the battery cells C1 to C2 measured by the voltage measurement circuit 113 at a first time point. n Based on the voltages of the battery cells C1 to C2 at the first time point, n The charging rate SOC1[i] of each battery cell is estimated, where i is a subscript for each battery cell and takes a value from 1 to n.

[0022] Here, the control unit 115 may acquire the measured voltage value of each battery cell after a specific time (for example, the time it takes for the power of the battery cell to stabilize after the power supply from the battery cell is stopped) has elapsed in an unloaded state (a state in which no load is connected to the battery cell and no current flows in or out of the battery cell).

[0023] The control unit 115 may acquire the charging rate corresponding to the measured voltage value by using, for example, a table (SOC (State Of Charge)-OCV (Open Circuit Voltage) table) in which each voltage value of the battery cell is associated with each charging rate value of the battery cell. Note that the SOC-OCV table may be generated in advance through an experiment or simulation and registered (set, recorded) in the control unit 115 or the like.

[0024] An example of the charging rate values ​​of the battery cells for each voltage value of the battery cells, which are recorded in the SOC-OCV table according to the embodiment, is shown in Fig. 3. In the example of Fig. 3, a curve 301 is shown which indicates that the higher the voltage of the battery cell, the higher the charging rate.

[0025] Furthermore, the control unit 115 may calculate an estimated value of the charging rate according to the measured voltage value, for example, by using a function for calculating the charging rate value of the battery cell from the voltage value of the battery cell. In this case, the control unit 115 may estimate (infer) the charging rate value of the battery cell from the voltage value of the battery cell, for example, by using AI (Artificial Intelligence) or the like.

[0026] Next, the control unit 115 calculates the voltages of the battery cells C1 to C2 measured by the voltage measurement circuit 113 at the second time point. n Based on the voltages of the battery cells C1 to C2 at the second time point, n The charging rate SOC2[i] of each of the batteries is estimated (step S102).

[0027] Here, the control unit 115 may acquire a measured value of the voltage of each battery cell after a specific time has elapsed under no load, for example. The control unit 115 may estimate the state of charge SOC2[i] of each battery cell using a method similar to that of step S101 described above.

[0028] The first point in time may be close to full discharge (the voltage is the discharge cut-off voltage), and the second point in time may be close to full charge. Note that the first point in time may be close to full charge, and the second point in time may be close to full discharge. In this case, the control unit 115 may, for example, n It may be determined whether the lowest voltage among the voltages of the battery cells C1 to C2 is within a specific range (specific range on the fully discharge side) corresponding to the voltage of the fully discharged battery. The specific range on the fully discharged battery side may be registered (set, recorded) in the control unit 115 or the like by an operator (administrator) or the like. Then, the control unit 115 may execute the process of step S101, for example, when the lowest voltage is within the specific range on the fully discharged battery side. Then, the control unit 115 may determine whether the lowest voltage among the voltages of the battery cells C1 to C2 is within a specific range (specific range on the fully discharged battery side) corresponding to the voltage of the fully discharged battery. n It may be determined whether the highest voltage among these voltages is within a specific range (full charge side specific range) corresponding to the voltage at full charge. The full charge side specific range may be registered (set, recorded) in the control unit 115 by an operator (administrator) or the like. Then, the control unit 115 may execute the process of step S102, for example, when the highest voltage is within the full charge side specific range.

[0029] 4 shows an example of the relationship between the capacity and voltage of each battery cell according to the embodiment. In the example of FIG. 4, voltage values ​​401 for each capacity of battery cell C1, voltage values ​​402 for each capacity of battery cell C2, and n 4 shows an example of voltage value 403 for each capacity. For example, the control unit 115 may determine the timing when the capacity of each battery cell is capacity 411 as a first time point, and the timing when the capacity of each battery cell is capacity 412 as a second time point.

[0030] The first time point may be when the charge rate is close to full charge, and the second time point may be when the charge rate is close to full discharge. In this case, the control unit 115 may determine, for example, the time when the capacity of each battery cell is capacity 412 in FIG. 4 as the first time point, and the time when the capacity of each battery cell is capacity 411 as the second time point. In this case, the control unit 115 may determine, for example, the time when the capacity of each battery cell is capacity 412 in FIG. 4 as the second time point. nThe control unit 115 may determine whether the highest voltage among the voltages of the battery cells C1 to C2 is within the full charge side specific range. Then, for example, if the highest voltage is within the full charge side specific range, the control unit 115 may execute the process of step S101. Then, for example, the control unit 115 may determine whether the highest voltage among the voltages of the battery cells C1 to C2 is within the full charge side specific range. n The control unit 115 may determine whether the lowest voltage among the voltages is within the fully discharged side specific range. Then, for example, if the lowest voltage is within the fully discharged side specific range, the control unit 115 may execute the process of step S102.

[0031] The full charge side specified range and the fully discharge side specified range may be registered (set, recorded) in advance in the control unit 115 or the like. In this case, the upper and lower limit values ​​of the full charge side specified range and the upper and lower limit values ​​of the fully discharge side specified range may be registered in advance. In this case, the full charge side specified range may be, for example, a range of voltage lower than the voltage of the battery cell when fully charged. Also, the fully discharge side specified range may be, for example, a range of voltage higher than the discharge end voltage of the battery cell. Note that the control unit 115 may update the full charge side specified range and the fully discharge side specified range using AI or the like.

[0032] Next, the control unit 115 calculates the currents of the battery cells C1 to C2 measured by the current measuring circuit 114 during the period from the first time point to the second time point. n The integrated value Σc (absolute value) of the current flowing through the battery cells C1 to C2 and the duration of the period is calculated (step S103). The unit of the integrated value Σc may be, for example, Ah (ampere-hour) or mAh (milliampere-hour). n are connected in series, the current value flowing through each battery cell is the same, and the integrated value Σc for each battery cell is the same.

[0033] Next, the control unit 115 controls the battery cells C1 to C nThe control unit 115 estimates the maximum capacity Qmax[i] of each battery cell (battery capacity when the charging rate is 100% (fully charged), in units of Ah or mAh, for example) (step S104). Here, the control unit 115 may calculate the estimated value of the maximum capacity of each battery cell, for example, using the following equation (1): Qmax[i]=Σc / (SOC1[i]-SOC2[i]) ···(1)

[0034] The processes of steps S105 and S106 below may be executed at any timing, for example, periodically. In this case, the control unit 115 may execute the processes of steps S105 and S106 below, for example, at a timing after a specific time has elapsed in a no-load state. For example, if the battery pack 10 is charged or discharged while the cell balance control (at least one of the processes of steps S105 and S106 below) is being executed, the control unit 115 may temporarily stop the cell balance control. Then, the control unit 115 may execute the processes of steps S105 and S106 again when a specific time has elapsed again in a no-load state. As a result, for example, the battery cells C1 to C n This allows cell balance control to be performed without repeating the process up to step S104, which estimates the maximum capacity of each of the above.

[0035] Next, the control unit 115 calculates the maximum capacity of each battery cell based on the estimated maximum capacity of each battery cell and the current charging rate of each battery cell. n A reference cell is determined from the above, and the discharge time length for each battery cell other than the reference cell is determined (step S105). This makes it possible to improve the accuracy of, for example, ATTF (average time to full charge) and ATTE (average time to empty) defined in the Smart Battery Data Specification of the PC battery standard.

[0036] (Example of matching the capacity of each battery cell when fully charged) The control unit 115 may determine the discharge time length for each battery cell so that the capacities of the battery cells are the same when fully charged (for example, when the charge rate of each battery cell is 100%). This allows the capacities of the battery cells to be the same when fully charged, reducing the risk of the battery cells being overcharged.

[0037] In this case, the control unit 115 may estimate the capacity ToMAXCap[i] of each battery cell until full charge based on, for example, the maximum capacity Qmax[i] of each battery cell and the current (for example, second point in time) charging rate SOC3[i] of each battery cell. Note that the control unit 115 may estimate the charging rate SOC3[i] of each battery cell based on the voltage of each battery cell measured by the voltage measurement circuit 113 using a method similar to that of step S101 described above.

[0038] Then, the control unit 115 may calculate the capacity (available capacity) ToMAXCap[i] of each battery cell until it is fully charged, for example, using the following formula (2).

[0039] ToMAXCap[i]=Qmax[i]×(100-SOC3[i]) ···(2)

[0040] Then, the control unit 115, for example, n Among them, the battery cell C with the largest full charge capacity ToMAXCap[i] is k may be determined as the reference battery cell.

[0041] Then, the control unit 115 determines, for example, the reference battery cell C k ToMAXCap[k] and the reference battery cell C k Each battery cell other than C j Based on ToMAXCap[j] and each battery cell C j The discharge time CBTime[j] for the reference battery cell C k It is a subscript for each battery cell other than k, and is a value from 1 to n other than k.

[0042] Then, the control unit 115 calculates the current of each battery cell C j The discharge time length (cell balancing time) CBTime[j] for each of the j-th power supply nodes may be determined. CBTime[j]=(ToMAXCap[k]-ToMAXCap[j]) / BalCurr ···(3)

[0043] This allows the reference battery cell C k Each battery cell other than C j For each battery cell C j The capacity of the reference battery cell C k The BalCurr is the voltage applied to the battery cell C of the cell balancing unit 111. j Switch S for j Battery cell C when turned on j The value of BalCurr may be registered (set, recorded) in advance in the control unit 115 or the like.

[0044] Note that the control unit 115 may execute a process of matching the capacities of the battery cells when fully charged, for example, when the highest voltage among the voltages of the battery cells is within a specific range on the full charge side. This allows the cell balancing process to be executed when, for example, one or more battery cells are close to being fully charged, thereby further reducing the risk of the battery cells being overcharged.

[0045] FIG. 5 shows battery cells C1, C2, and C n 5 shows an example of the transitions 501 to 503 of the charging rates of the battery cells C1 to C2. n The process of step S101 is executed at the first time point t1 when the lowest voltage among the voltages of the battery cells C1 to C2 is within the specific range on the fully discharge side. n At the second time point t2 when the highest voltage among the voltages is within the full charge side specific range, the processes from step S102 to step S106, which will be described later, are executed.

[0046] (Example of matching the capacity of each battery cell when fully discharged) The control unit 115 may determine the discharge time length for each battery cell so that the capacities of the battery cells are the same when they are completely discharged (deeply discharged, at the discharge cut-off voltage, for example, when the charge rate of each battery cell is approximately 0%). This allows the capacities of the battery cells to be the same when they are completely discharged, for example, and therefore reduces over-discharge of the battery cells.

[0047] In this case, the control unit 115 may estimate the capacity (remaining capacity) ToMINCap[i] of each battery cell until full discharge based on the maximum capacity Qmax[i] of each battery cell and the current (e.g., second point in time) charging rate SOC4[i] of each battery cell. Note that the control unit 115 may estimate the charging rate SOC4[i] of each battery cell based on the voltage of each battery cell measured by the voltage measurement circuit 113 using a method similar to that of step S101 described above.

[0048] Then, the control unit 115 may calculate the capacity ToMINCap[i] of each battery cell until it is fully discharged, for example, using the following equation (4). ToMINCap[i]=Qmax[i]×(SOC4[i]) ···(4)

[0049] Then, the control unit 115, for example, n Among them, the battery cell C with the smallest capacity ToMINCap[i] until full discharge k may be determined as the reference battery cell.

[0050] Then, the control unit 115 determines, for example, the reference battery cell C k ToMINCap[k] and the reference battery cell C k Each battery cell other than C j Based on ToMINCap[j] and each battery cell C j As described above, j is the discharge time length CBTime[j] of the reference battery cell C k It is a subscript for each battery cell other than k, and is a value from 1 to n other than k.

[0051] Then, the control unit 115 calculates the voltage of each battery cell C j The discharge time length (cell balancing time) CBTime[j] for each of the j-th power supply nodes may be determined. CBTime[j]=(ToMINCap[j]-ToMINCap[k]) / BalCurr ···(5)

[0052] This allows the reference battery cell C k Each battery cell other than C j For each battery cell C j The capacity of the reference battery cell C k The battery can be discharged for a length of time equal to the full discharge capacity of the battery.

[0053] Note that the control unit 115 may execute a process of matching the capacities of the battery cells when fully discharged, for example, when the lowest voltage among the voltages of the battery cells is within a specific range on the fully discharged side. This allows the cell balancing process to be executed when, for example, one or more battery cells are close to being fully discharged, thereby further reducing the risk of the battery cells becoming over-discharged.

[0054] FIG. 6 shows battery cells C1, C2, and C n 6 shows examples of the transitions 601 to 603 of the charging rates of the battery cells C1 to C2. n The process of step S101 is executed at the first time point t1 when the highest voltage among the voltages of the battery cells C1 to C2 is within the full charge side specific range. n At the second time point t2 when the lowest voltage among the voltages is within the complete discharge side specific range, the processes from step S102 to step S106, which will be described later, are executed.

[0055] (Example of matching the capacity of each battery cell when fully charged and fully discharged) The control unit 115 may execute the process of matching the capacities of the battery cells when fully charged and the process of matching the capacities of the battery cells when fully discharged at different times. This makes it possible to reduce overcharging and overdischarging of the battery cells, for example, because the capacities of the battery cells when fully charged and when fully discharged match.

[0056] In this case, for example, when the highest voltage among the voltages of the battery cells is within a specific range on the fully charged side, the control unit 115 may execute the process of matching the capacities of the battery cells when fully charged described above.Also, for example, when the lowest voltage among the voltages of the battery cells is within a specific range corresponding to the voltages when fully discharged described above, the control unit 115 may execute the process of matching the capacities of the battery cells when fully discharged described above.

[0057] Next, the control unit 115 controls the battery cells C1 to C n Each battery cell C other than the reference cell j Here, the control unit 115 controls the one or more battery cells C of the cell balance unit 111 to discharge, for example. j Switch S for j is turned ON for the calculated CBTime[j] time period, thereby performing discharging for cell balancing. This makes it possible to perform cell balancing only on the battery pack 10 side, for example, without requiring a command for cell balancing control from the system side (main body 20 side). Also, for example, when the device 1 is stored in an unused state for a long period of time, cell balancing control can be performed without the user being aware of it. Also, cell balancing control on the discharging side becomes possible.

[0058] It is known that differences in the operating environment, manufacturing variations, and other factors can cause differences in the rate of deterioration of each cell. In this case, differences in the capacity of each cell occur. Furthermore, even if the capacity of each cell is the same, the charging rate of each cell may differ. Therefore, even if cell balancing is performed to make the voltage of each cell the same, the capacities of each cell may not match. According to the present disclosure, more appropriate cell balancing control can be performed even when both the capacity and charging rate of each cell vary.

[0059] (Regarding the control unit 115) Fig. 7 is a diagram showing an example of the configuration of the control unit 115 according to the embodiment. In the example of Fig. 7, the control unit 115 includes a processor 101, a memory 102, and a communication interface 103. These units may be connected by a bus or the like. The memory 102 stores at least a part of the program 104. The communication interface 103 includes an interface required for communication with other network elements.

[0060] When the program 104 is executed by the processor 101, memory 102, and the like in cooperation with each other, the computer 100 performs at least some of the processing of the embodiments of the present disclosure. The memory 102 may be of any type. As a non-limiting example, the memory 102 may be a non-transitory computer-readable storage medium. The memory 102 may also be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. Although only one memory 102 is shown in the computer 100, several physically different memory modules may exist in the computer 100. The processor 101 may be of any type. The processor 101 may include one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture, as a non-limiting example. The computer 100 may have multiple processors, such as application-specific integrated circuit chips that are time-slaved to a clock that synchronizes the main processor.

[0061] The program can be stored and provided to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible recording media. Examples of non-transitory computer-readable media include magnetic recording media, magneto-optical recording media, optical disk media, and semiconductor memory. Magnetic recording media include, for example, flexible disks, magnetic tapes, and hard disk drives. Magneto-optical recording media include, for example, magneto-optical disks. Optical disk media include, for example, Blu-ray discs, CD (Compact Disc)-ROMs (Read Only Memory), CD-Rs (Recordable), and CD-RWs (Rewritable). Semiconductor memory includes, for example, solid-state drives, mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (Random Access Memory). The program may also be provided to a computer by various types of temporary computer-readable media. Examples of temporary computer-readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire or an optical fiber, or via a wireless communication path.

[0062] The invention made by the present inventor has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the embodiments already described, and various modifications are possible within the scope of the gist of the invention. [Explanation of symbols]

[0063] 1 equipment 10 Battery pack C1~C n Battery cell 11 Battery management IC 111 Cell balance section 112 Selection circuit 113 Voltage measurement circuit 114 Current measurement circuit 115 Control Unit R1~R n resistance S1~S n switch SC1~SC n Switch Control Circuit P1~P3 connection points 20 Main Unit

Claims

1. a voltage measurement circuit that measures the voltages of the first battery cell and the second battery cell that are connected in series; a current measurement circuit for measuring a current flowing through the first battery cell and the second battery cell; a control unit that controls discharging of at least one of the first battery cell and the second battery cell, The control unit estimating a charging rate of each of the first battery cell and the second battery cell at a first time point based on the voltages of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at the first time point; estimating a charging rate of each of the first battery cell and the second battery cell at a second time point, based on the voltages of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at the second time point, which is different from the first time point; calculating an integrated value of currents flowing through the first battery cell and the second battery cell during a period from the first time point to the second time point; estimating a maximum capacity of the first battery cell based on the charging rate of the first battery cell at the first time point, the charging rate of the first battery cell at the second time point, and the integrated value; estimating a maximum capacity of the second battery cell based on the charging rate of the second battery cell at the first time point, the charging rate of the second battery cell at the second time point, and the integrated value; determining a reference battery cell from the first battery cell and the second battery cell based on a maximum capacity of the first battery cell, a charging rate of the first battery cell, a maximum capacity of the second battery cell, and a charging rate of the second battery cell; discharging the first battery cell and the second battery cell other than the reference battery cell; Semiconductor device.

2. The control unit estimating a capacity until a full charge of the first battery cell based on the estimated maximum capacity of the first battery cell and the charging rate of the first battery cell; estimating a capacity until full charge of the second battery cell based on the estimated maximum capacity of the second battery cell and the charging rate of the second battery cell; determining, as the reference battery cell, one of the first battery cell and the second battery cell that has the largest capacity until fully charged; The semiconductor device according to claim 1 .

3. The control unit discharging the battery cells other than the reference battery cell among the first battery cell and the second battery cell for a time period during which the full charge capacity of the battery cell becomes equal to the full charge capacity of the reference battery cell; The semiconductor device according to claim 2 .

4. The control unit When the lowest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to a voltage at a time of full discharge, estimating the charging rates of the first battery cell and the second battery cell at the first time point; When the highest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to a voltage at a fully charged state, the charging rates of the first battery cell and the second battery cell at the second time point are estimated.

4. The semiconductor device according to claim 2.

5. The control unit When the highest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to the voltages at full charge, the first battery cell and the second battery cell other than the reference battery cell are caused to discharge.

4. The semiconductor device according to claim 2.

6. The control unit estimating a capacity until a full discharge of the first battery cell based on the estimated maximum capacity of the first battery cell and the charging rate of the first battery cell; estimating a capacity of the second battery cell until it is fully discharged based on the estimated maximum capacity of the second battery cell and the charging rate of the second battery cell; determining, as the reference battery cell, one of the first battery cell and the second battery cell that has the smallest capacity until fully discharged; The semiconductor device according to claim 1 .

7. The control unit discharging the first battery cell and the second battery cell other than the reference battery cell for a period of time such that the capacity of the battery cell until full discharge becomes equal to the capacity of the reference battery cell until full discharge; The semiconductor device according to claim 6.

8. The control unit When the highest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to a voltage at a fully charged state, the charging rates of the first battery cell and the second battery cell at the first time point are estimated; When the lowest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to a voltage at a time of full discharge, the charging rates of the first battery cell and the second battery cell at the second time point are estimated.

8. The semiconductor device according to claim 6.

9. The control unit When the lowest voltage of the first battery cell and the second battery cell is within a specific range corresponding to the voltage at the time of full discharge, the first battery cell and the second battery cell other than the reference battery cell are caused to discharge.

8. The semiconductor device according to claim 6.

10. The semiconductor device estimating a charging rate of each of the first battery cell and the second battery cell at a first time point based on the voltages of the first battery cell and the second battery cell measured at the first time point by a voltage measurement circuit that measures the voltages of the first battery cell and the second battery cell connected in series; estimating charging rates of the first battery cell and the second battery cell at a second time point based on voltages of the first battery cell and the second battery cell measured by the voltage measurement circuit at the second time point, the second time point being different from the first time point; calculating an integrated value of the current flowing through the first battery cell and the second battery cell during a period from the first time point to the second time point, the integrated value being measured by a current measurement circuit that measures the current flowing through the first battery cell and the second battery cell; estimating a maximum capacity of the first battery cell based on the charging rate of the first battery cell at the first time point, the charging rate of the first battery cell at the second time point, and the integrated value; estimating a maximum capacity of the second battery cell based on the charging rate of the second battery cell at the first time point, the charging rate of the second battery cell at the second time point, and the integrated value; determining a reference battery cell from the first battery cell and the second battery cell based on a maximum capacity of the first battery cell, a charging rate of the first battery cell, a maximum capacity of the second battery cell, and a charging rate of the second battery cell; discharging the first battery cell and the second battery cell other than the reference battery cell; Cell balancing control method.

11. The semiconductor device is estimating a capacity until a full charge of the first battery cell based on the estimated maximum capacity of the first battery cell and the charging rate of the first battery cell; estimating a capacity until full charge of the second battery cell based on the estimated maximum capacity of the second battery cell and the charging rate of the second battery cell; determining, as the reference battery cell, one of the first battery cell and the second battery cell that has the largest capacity until fully charged; The cell balancing control method according to claim 10.

12. The semiconductor device is discharging the battery cells other than the reference battery cell among the first battery cell and the second battery cell for a time period during which the full charge capacity of the battery cell becomes equal to the full charge capacity of the reference battery cell; The cell balancing control method according to claim 11.

13. The semiconductor device is When the lowest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to a voltage at a time of full discharge, estimating the charging rates of the first battery cell and the second battery cell at the first time point; When the highest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to a voltage at a fully charged state, the charging rates of the first battery cell and the second battery cell at the second time point are estimated. The cell balancing control method according to claim 11 or 12.

14. The semiconductor device is When the highest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to the voltages at full charge, the first battery cell and the second battery cell other than the reference battery cell are caused to discharge. The cell balancing control method according to claim 11 or 12.

15. The semiconductor device is estimating a capacity until a full discharge of the first battery cell based on the estimated maximum capacity of the first battery cell and the charging rate of the first battery cell; estimating a capacity of the second battery cell until it is fully discharged based on the estimated maximum capacity of the second battery cell and the charging rate of the second battery cell; determining, as the reference battery cell, one of the first battery cell and the second battery cell that has the smallest capacity until fully discharged; The cell balancing control method according to claim 10.

16. The semiconductor device is discharging the first battery cell and the second battery cell other than the reference battery cell for a period of time such that the capacity of the battery cell until full discharge becomes equal to the capacity of the reference battery cell until full discharge; The cell balancing control method according to claim 15.

17. The semiconductor device is When the highest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to a voltage at a fully charged state, the charging rates of the first battery cell and the second battery cell at the first time point are estimated; When the lowest voltage among the voltages of the first battery cell and the second battery cell is within a specific range corresponding to a voltage at a time of full discharge, the charging rates of the first battery cell and the second battery cell at the second time point are estimated. The cell balancing control method according to claim 15 or 16.

18. The semiconductor device is When the lowest voltage of the first battery cell and the second battery cell is within a specific range corresponding to the voltage at the time of full discharge, the first battery cell and the second battery cell other than the reference battery cell are caused to discharge. The cell balancing control method according to claim 15 or 16.

19. a first battery cell and a second battery cell connected in series; a voltage measurement circuit that measures the voltages of the first battery cell and the second battery cell; a current measurement circuit for measuring a current flowing through the first battery cell and the second battery cell; a control unit that controls discharging of at least one of the first battery cell and the second battery cell, The control unit estimating a charging rate of each of the first battery cell and the second battery cell at a first time point based on the voltages of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at the first time point; estimating a charging rate of each of the first battery cell and the second battery cell at a second time point, based on the voltages of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at the second time point, which is different from the first time point; calculating an integrated value of currents flowing through the first battery cell and the second battery cell during a period from the first time point to the second time point; estimating a maximum capacity of the first battery cell based on the charging rate of the first battery cell at the first time point, the charging rate of the first battery cell at the second time point, and the integrated value; estimating a maximum capacity of the second battery cell based on the charging rate of the second battery cell at the first time point, the charging rate of the second battery cell at the second time point, and the integrated value; determining a reference battery cell from the first battery cell and the second battery cell based on a maximum capacity of the first battery cell, a charging rate of the first battery cell, a maximum capacity of the second battery cell, and a charging rate of the second battery cell; discharging the first battery cell and the second battery cell other than the reference battery cell; Battery pack.

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