Semiconductor device, method of controlling unit balancing,

Abstract

The embodiment of the invention relates to semiconductor equipment, a method for controlling unit balance and a battery pack. An improved cell balancing is provided. Estimating a state of charge of each battery cell at each point in time based on a voltage of each cell coupled in series, calculating an integrated value of a current flowing through the plurality of battery cells during a period between each point in time, the maximum capacity of each cell is estimated based on the state of charge and the integrated value of the current of each cell at each time point, a reference cell is determined based on the maximum capacity and the state of charge of each cell, and cells other than the reference cell are discharged.

Description

[0001] Cross Reference to Related Applications

[0002] The disclosure of Japanese Patent Application No. 2024-063524 filed on April 10, 2024, including the specification, drawings and abstract, is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present disclosure relates to a semiconductor device, a cell balancing control method, and a battery pack. BACKGROUND

[0004] Conventionally, it is well known that imbalance of cell capacity (cell imbalance) occurs due to manufacturing differences and individual deterioration differences during long-term use of battery cells. Charging or discharging in this state can cause some cells to be overcharged or overdischarged. In addition, in the case where some cells are overcharged or overdischarged, charging and discharging can be stopped due to the protection function of the relevant cells. In this case, even if the other cells are in a usable state, the original performance can not be fully utilized.

[0005] The disclosed technology is listed as follows.

[0006] [Patent Literature 1] Japanese Unexamined Patent Application Publication No. 2019-058013

[0007] In a battery assembly composed of a plurality of battery cells, a technology known as cell balancing equalizes parameters such as the voltage of each cell to prevent overdischarge and overcharge due to variations in the remaining capacity between cells (see, for example, Patent Literature 1). Patent Literature 1 discloses a technology for performing cell balancing control using a flying capacitor. In addition, as a method for performing cell balancing control, a technology is known in which the voltage of each cell is measured periodically, the discharge of the cells is performed when the voltage difference between each cell exceeds a cell balancing start threshold, and the discharge of the cells is terminated when the voltage difference between each cell is lower than a cell balancing end threshold. SUMMARY

[0008] The voltage of the cells varies due to aging, operating temperature, and discharge current. Therefore, there is a problem that even if cell balancing is performed to align the voltage of the cells, the capacity of the cells does not necessarily match. Other objects and novel features will become apparent from the description and drawings of this specification.

[0009] In one embodiment of the present disclosure, a semiconductor device is provided, including: a voltage measurement circuit configured to measure a voltage of each of first and second battery cells coupled in series,

[0010] a current measurement circuit configured to measure a current flowing through the first and second battery cells, and a control unit configured to control discharging of at least one of the first and second battery cells,

[0011] wherein the control unit estimates a state of charge of each of the first and second battery cells at a first point in time based on a voltage of each of the first and second battery cells measured by the voltage measurement circuit at the first point in time, estimates a state of charge of each of the first and second battery cells at a second point in time different from the first point in time based on a voltage of each of the first and second battery cells measured by the voltage measurement circuit at the second point in time, calculates an integrated value of the current flowing through the first and second battery cells during a period from the first point in time to the second point in time,

[0012] estimating a maximum capacity of the first battery cell based on the state of charge of the first battery cell at the first time point, the state of charge of the first battery cell at the second time point, and the integrated value of the current, estimating a maximum capacity of the second battery cell based on the state of charge of the second battery cell at the first time point, the state of charge of the second battery cell at the second time point, and the integrated value of the current flowing through the second battery cell, determining a reference battery cell from among the first battery cell and the second battery cell based on the maximum capacity of the first battery cell, the state of charge of the first battery cell, the maximum capacity of the second battery cell, and the state of charge of the second battery cell, and discharging the battery cells other than the reference battery cell among the first battery cell and the second battery cell. Further, in one embodiment of the disclosure, there is provided a method of cell balancing, including: measuring a voltage of each of first and second battery cells coupled in series, measuring a current flowing through the first and second battery cells, estimating a state of charge of each of the first and second battery cells at a first time point based on the voltage of each of the first and second battery cells measured at the first time point, estimating a state of charge of each of the first and second battery cells at a second time point different from the first time point based on the voltage of each of the first and second battery cells measured at the second time point, calculating an integrated value of the current flowing through the first and second battery cells 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 state of charge of the first battery cell at the first time point, the state of charge of the first battery cell at the second time point, and the integrated value of the current, estimating a maximum capacity of the second battery cell based on the state of charge of the second battery cell at the first time point, the state of charge of the second battery cell at the second time point, and the integrated value of the current, determining a reference battery cell from among the first battery cell and the second battery cell based on the maximum capacity of the first battery cell, the state of charge of the first battery cell, the maximum capacity of the second battery cell, and the state of charge of the second battery cell, and discharging the battery cells other than the reference battery cell among the first battery cell and the second battery cell.

[0013] In one embodiment of the present disclosure, a battery pack is provided, including: a first battery cell and a second battery cell coupled in series, a voltage measurement circuit configured to measure a voltage of each of the first battery cell and the second battery cell, a current measurement circuit configured to measure a current flowing through the first battery cell and the second battery cell, and a control unit configured to control discharging of at least one of the first battery cell and the second battery cell, wherein the control unit estimates a state of charge of each of the first battery cell and the second battery cell at a first time point based on a voltage of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at the first time point, estimates a state of charge of each of the first battery cell and the second battery cell at a second time point different from the first time point based on a voltage of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at the second time point, calculates 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, estimates a maximum capacity of the first battery cell based on the state of charge of the first battery cell at the first time point, the state of charge of the first battery cell at the second time point, and the integrated value of the current, estimates a maximum capacity of the second battery cell based on the state of charge of the second battery cell at the first time point, the state of charge of the second battery cell at the second time point, and the integrated value of the current, determines a reference battery cell from among the first battery cell and the second battery cell based on the maximum capacity of the first battery cell, the state of charge of the first battery cell, the maximum capacity of the second battery cell, and the state of charge of the second battery cell, and discharges a battery cell other than the reference battery cell among the first battery cell and the second battery cell.

[0014] According to one aspect, cell balancing can be performed more appropriately. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 FIG. 1 is a diagram illustrating an example of a configuration of an apparatus according to an embodiment.

[0016] Figure 2 FIG. 2 is a flowchart illustrating an example of a process of a control unit according to an embodiment.

[0017] Figure 3 FIG. 3 is a diagram illustrating an example of data recorded in an SOC-OCV table according to an embodiment.

[0018] Figure 4 FIG. 4 is a diagram illustrating an example of a relationship between a capacity and a voltage of each battery cell according to an embodiment.

[0019] Figure 5 FIG. 5 is a timing chart illustrating an example of a timing of a cell balancing process according to an embodiment.

[0020] Figure 6 is a timing chart showing an example of a timing of a cell balancing process according to an embodiment.

[0021] Figure 7 is a diagram showing an example of a configuration of a control unit according to an embodiment. DETAILED DESCRIPTION

[0022] The principles of the present disclosure are described with reference to several exemplary embodiments. These embodiments are described only for illustrative purposes and are not intended to limit the scope of the present disclosure, and it is understood that they help those skilled in the art to understand and implement the present disclosure. The disclosure described in this specification can be implemented in various ways other than those described below.

[0023] In the following description and claims, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs unless otherwise defined.

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0025] <Configuration>

[0026] Referring to Figure 1 , a configuration of equipment 1 according to an embodiment will be described. Figure 1 is a diagram showing an example of a configuration of equipment 1 according to an embodiment. The equipment 1 can be, for example, a personal computer, a server, a household appliance, factory equipment, or a vehicle, etc. Examples of the vehicle in the present disclosure can include, for example, an electric vehicle (EV), a hybrid electric vehicle (HEV), an electric motorcycle, an electric assist bicycle, and an electric scooter, etc.

[0027] In Figure 1 an example, the equipment 1 has a battery pack 10 and a main body 20. The main body 20 is a main body portion of the equipment 1. The battery pack 10 can be housed within an outer case of the main body 20.

[0028] The battery pack 10 has battery cells C1 to Cn (n is an integer of 2 or more) and a battery management integrated circuit 11 (battery management IC 11) (an example of a "semiconductor device"). The battery cells C1 to Cn are coupled in series with the positive electrode side electrically coupled to the main body 20 at a connection point P1 and the negative electrode side electrically coupled to the main body 20 at a connection point P2. In addition, it is electrically coupled to the main body 20 at a communication connection point P3 for notification of a battery state, etc.

[0029] The battery management IC 11 has a cell balancing section 111, a selection circuit 112, a voltage measurement circuit 113, a current measurement circuit 114, and a control unit 115. The cell balancing section 111 has a combination of a resistor R1 to Rn, a switch S1 to Sn, and a switch control circuit SC1 to SCn for controlling each switch for each of the battery cells C1 to Cn.

[0030] The selection circuit 112 is a circuit that electrically connects only one of the battery cells C1 to Cn designated by the control unit 115 to the voltage measurement circuit 113.

[0031] The voltage measurement circuit 113 measures the voltage of each of the battery cells C1 to Cn coupled in series. In Figure 1 the example, the voltage measurement circuit 113 is a circuit that measures the voltage of the battery cell selected from among the battery cells C1 to Cn by the selection circuit 112.

[0032] The current measurement circuit 114 measures the current flowing through the battery cells C1 to Cn coupled in series. In Figure 1 the example, the current measurement circuit 114 measures the current flowing through the battery cells C1 to Cn based on the magnitude of the voltage drop across a sense resistor Rs provided in an electrical circuit to which the battery cells C1 to Cn are coupled.The control unit 115 controls discharging of at least one of the battery cells C1 to Cn.

[0033] <Process of the control unit 115>

[0034] Next, an example of the process of the control unit 115 according to the embodiment will be described with reference to Figures 2 to 6 Figure 2 is a flowchart showing an example of the process of the control unit 115 according to the embodiment. Figure 3 is a graph showing an example of data recorded in the SOC-OCV table according to the embodiment. Figure 4 is a graph showing an example of the relationship between the capacity and the voltage of each battery cell according to the embodiment. Figure 5 and Figure 6 is a timing chart showing an example of the timing of the cell balancing process according to the embodiment. The process of Figure 2 may be performed at regular timing in, for example, a no-load condition (a state in which no load is connected to the battery cells and no current flows into or out of the battery cells).

[0035] In step S101, the control unit 115 estimates the state of charge SOC1[i] of each of the battery cells C1 to Cn at the first time point on the basis of the voltage of each of the battery cells C1 to Cn measured by the voltage measurement circuit 113 at the first time point. It should be noted that i is an index for each battery cell, and can be an arbitrary value from 1 to n.

[0036] Here, for example, the control unit 115 can acquire the voltage measurement value of each battery cell after a certain time elapses in a no-load state (a state in which no load is coupled to the battery cell, and no current flows into or out of the battery cell) (for example, a time required for the power of the battery cell to stabilize after the supply of power from the battery cell is stopped).

[0037] For example, the control unit 115 can use a table (SOC (State of Charge)-OCV (Open Circuit Voltage) table) that associates each voltage value of the battery cell with each state of charge value of the battery cell to obtain the state of charge corresponding to the measured voltage value. It should be noted that the SOC-OCV table can be generated by previous experiments or simulations, and registered (set, recorded) in the control unit 115 or the like.

[0038] Figure 3 An example of the state of charge value of the battery cell recorded in the SOC-OCV table in relation to the embodiment is shown. 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 state of charge. Figure 3

[0039] In addition, for example, the control unit 115 can calculate the estimated state of charge corresponding to the measured voltage value using a function or the like for calculating the state of charge value from the voltage value of the battery cell. In this case, for example, the control unit 115 can estimate (infer) the state of charge value from the voltage value of the battery cell using AI (Artificial Intelligence) or the like.

[0040] Subsequently, in step S102, the control unit 115 estimates the state of charge SOC2[i] of each of the battery cells C1 to Cn at the second time point on the basis of the voltage of each of the battery cells C1 to Cn measured by the voltage measurement circuit 113 at the second time point.

[0041] Here, for example, the control unit 115 can acquire the voltage measurement value of each battery cell after a certain time elapses in a no-load state. The control unit 115 can estimate the state of charge SOC2[i] of each battery cell using the same method as described in step S101.

[0042] ​The first time point may be close to full discharge (voltage at the end of discharge), and the second time point may be close to full charge. It should be noted that the first time point may be close to full charge, and the second time point may be close to full discharge. In this case, for example, the control unit 115 may determine whether the lowest voltage among the voltages of each of the battery cells C1 to Cn is within a predetermined range corresponding to the voltage at full discharge (predetermined range on the full discharge side). It should be noted that the predetermined range on the full discharge side may be registered (set, recorded) in the control unit 115 or the like by an operator (administrator), etc. Then, for example, when the lowest voltage is within the predetermined range on the full discharge side, the control unit 115 may perform the processing of step S101. Furthermore, the control unit 115 may determine whether the highest voltage among the voltages of each of the battery cells C1 to Cn is within a predetermined range corresponding to the voltage at full charge (predetermined range on the full charge side). The predetermined range on the full charge side may be registered (set, recorded) in the control unit 115 or the like by an operator (administrator), etc. Also, for example, when the highest voltage is within a predetermined range on the fully charged side, the control unit 115 may perform the process of step S102 .

[0043] Figure 4 An example of the relationship between the capacity and voltage of each battery cell according to an embodiment is shown. Figure 4 In the example shown, voltage values ​​401 for each capacity of battery cell C1, voltage values ​​402 for each capacity of battery cell C2, and voltage values ​​403 for each capacity of battery cell Cn are shown. For example, the control unit 115 may define the timing when the capacity of each battery cell is capacity 411 as the first time point, and define the timing when the capacity of each battery cell is capacity 412 as the second time point.

[0044] In contrast to the above, the first time point can be when the charge rate is close to full charge, and the second time point can be when the charge rate is close to full discharge. In this case, the control unit 115 can, for example, take the timing when the capacity of each battery cell is the capacity 412 as the first time point, and take the timing when the capacity of each battery cell is the capacity 411 as the second time point. In this case, the control unit 115 can determine whether the highest voltage among the voltages of each of the battery cells C1 to Cn is within the predetermined range on the full charge side. Also, the control unit 115 can, for example, execute the processing of step S101 when the highest voltage is within the predetermined range on the full charge side. The control unit 115 can determine whether the lowest voltage among the voltages of each of the battery cells C1 to Cn is within the predetermined range on the full discharge side, for example, when the lowest voltage is within the predetermined range on the full discharge side. The control unit 115 can execute the processing of step S102, for example, when the lowest voltage is within the predetermined range on the full discharge side.

[0045] It should be noted that the predetermined range on the full charge side and the predetermined range on the full discharge side can be pre-registered (set, recorded) in the control unit 115 or the like. In this case, the upper and lower limits of the predetermined range on the full charge side and the upper and lower limits of the predetermined range on the full discharge side can be pre-registered. In this case, the predetermined range on the full charge side can be, for example, a voltage range lower than the voltage of the battery cell at full charge. Also, the predetermined range on the full discharge side can be, for example, a voltage range higher than the discharge termination voltage of the battery cell. It should be noted that the control unit 115 can update the predetermined range on the full charge side and the predetermined range on the full discharge side using AI or the like.

[0046] Subsequently, the control unit 115 calculates the integral value Sc (absolute value) of the current flowing through the battery cells C1 to Cn during the period from the first time point to the second time point measured by the current measurement circuit 114 (step S103). It should be noted that the unit of the integral value Sc can be, for example, Ah (Ampere-hour) or mAh (milli-Ampere-hour). It should be noted that since the battery cells C1 to Cn are coupled in series, the current value flowing through each battery cell is the same, and the value of the integral value Sc for each battery cell is the same.

[0047] Subsequently, the control unit 115 estimates the maximum capacity (cell capacity at 100% charge rate (full charge)) of each of the battery cells C1 to Cn. The unit can be, for example, Ah or mAh) Qmax[i] (step S104). Here, the control unit 115 can calculate the estimated value of the maximum capacity of each battery cell by the following formula (1).

[0048] Q max[i] =∑c / (SOC1[i] - SOC2[i])...(1)

[0049] It should be noted that the processes of step S105 and step S106 can be executed at any timing, for example, periodically. In this case, the control unit 115 can execute the processes of step S105 and step S106 at a timing after a predetermined time elapses in the no-load state, for example. It should be noted that, for example, when the battery pack 10 is charged or discharged while the cell balancing control (at least one of the processes in step S105 and step S106) is being executed, the control unit 115 can temporarily stop the cell balancing control. Then, the control unit 115 can execute the processes of step S105 and step S106 again when the predetermined time elapses again in the no-load state. As a result, for example, the process of estimating the maximum capacity of each of the battery cells C1 to Cn before step S104 need not be repeated to execute the cell balancing control.

[0050] Subsequently, based on the current charge rate of each battery cell and the estimated maximum capacity of each battery cell, the control unit 115 determines a reference cell from among the battery cells C1 to Cn and determines a discharge period of each battery cell other than the reference cell (step S105). As a result, for example, the accuracy of ATTF (average time to full) and ATTE (average time to empty) defined in the PC Battery Standard Intelligent Battery Data Specification can be improved.

[0051] <Example of matching the capacity of each battery cell at full charge>

[0052] For example, the control unit 115 can determine the discharge period for each battery cell to match the capacity of each battery cell at full charge (for example, when the charge rate of each battery cell reaches 100%). As a result, for example, since the capacity of each battery cell at full charge is matched, the occurrence of overcharging of the battery cells can be reduced.

[0053] In this case, the control unit 115 can estimate the pre-full charge capacity ToMAXCap[i] for each battery cell based on the maximum capacity Qmax[i] of each battery cell and the current charge rate SOC3[i] of each battery cell (for example, at the second point in time), for example. Further, using a method similar to step S101 described above, the control unit 115 can estimate the charge rate SOC3[i] of each battery cell based on the voltage of each battery cell measured by the voltage measurement circuit 113.

[0054] Then, the control unit 115 can calculate the pre-full charge capacity (available capacity) ToMAXCap[i] for each battery cell by, for example, the following equation (2).

[0055] ToMAXCap[i] = Q max [i] x (100 - SOC3[i])... (2)

[0056] Then, the control unit 115 can determine, for example, the battery cell Ck having the maximum value of the full charge capacity ToMAXCap[i] among the battery cells C1 to Cn as the reference battery cell.

[0057] Then, the control unit 115 can determine, for example, the discharge period CBTime[j] for each battery cell Cj based on ToMAXCap[k] of the reference battery cell Ck and ToMAXCap[j] of each battery cell Cj other than the reference battery cell Ck. Here, j is the index of each battery cell other than the reference battery cell Ck, and is a value other than k in 1 to n.

[0058] Then, the control unit 115 can determine, for example, the discharge period (cell balancing time) CBTime[j] for each battery cell Cj by the following equation (3).

[0059] CBTime[j] = (ToMAXCap[k] - ToMAXCap[j]) / BalCurr... (3)

[0060] As a result, each battery cell Cj other than the reference battery cell Ck can be discharged for a period of time until the full charge capacity of each battery cell Cj is the same as that of the reference battery cell Ck. Here, BalCurr is the discharge current value of the battery cell Cj when the switch Sj for the battery cell Cj in the battery cell balancing selection 111 is turned on. The value of BalCurr can be pre-registered (set, recorded) in the control unit 115 or the like.

[0061] Further, the control unit 115 can execute the process of matching the capacity of each battery cell at the time of full charge, for example, when the highest voltage among the voltages of each battery cell is within a predetermined range on the full charge side. As a result, for example, the battery cell balancing processing is executed when one or more battery cells are close to full charge, thereby further reducing the possibility of battery cell overcharging.

[0062] Figure 5 Examples of transitions 501-503 in the charge rate of the battery cells C1, C2, Cn according to the embodiment are shown. In the example shown in FIG. 5, the battery cells C1, C2, Cn are discharged to the same level of charge at the same time. Figure 5In the example of FIG. 1, the process of step S101 is executed at a first time point tl at which the lowest voltage among the voltages of the battery cells Cl to Cn is within a predetermined range on the fully discharged side. Further, the process from step S102 to step S106 described later is executed at a second time point t2 at which the highest voltage among the voltages of each of the battery cells Cl to Cn is within a predetermined range of full charge.

[0063] <Example of Matching Each Cell Capacity at Full Discharge>

[0064] The control unit 115 can determine the discharge period for each battery cell to match the capacity of each battery cell at full discharge (deep discharge, at a discharge termination voltage, for example, when the charge rate of each battery cell is approximately 0%). As a result, for example, the occurrence of battery cell overdischarge can be reduced due to the matching of the capacity of each battery cell at full discharge.

[0065] In this case, the control unit 115 can estimate the full discharge before capacity (remaining capacity) ToMINCap[i] of each battery cell based on, for example, the maximum capacity Qmax[i] of each battery cell and the current charge rate SOC4[i] of each battery cell (for example, at the second time point). Further, using a method similar to the method described in step S101, the control unit 115 can estimate the charge rate SOC4[i] of each battery cell based on the voltage of each battery cell measured by the voltage measurement circuit 113.

[0066] Then, the control unit 115 can calculate the full discharge before capacity ToMINCap[i] for each battery cell, for example, by the following equation (4).

[0067] ToMINCap[i] = Q max [i] x (SOC4[i])... (4)

[0068] Then, the control unit 115 can determine, for example, the battery cell Ck having the minimum value of the full discharge before capacity ToMINCap[i] among the battery cells Cl to Cn as the reference battery cell.

[0069] Then, the control unit 115 can determine, for example, the discharge period CBTime[j] for each battery cell Cj based on ToMINCap[k] of the reference battery cell Ck and ToMINCap[j] of each battery cell Cj other than the reference battery cell Ck. As described above, j is the index of each battery cell other than the reference battery cell Ck, and is a value other than k among 1 to n.

[0070] Then, the control unit 115 may determine a discharge period (cell balancing time) CBTime[j] for each battery cell Cj, for example, by the following equation (5).

[0071] CBTime[j]=(ToMINCap[j]-ToMINCap[k]) / BalCurr...(5)

[0072] As a result, each battery cell Cj except the reference battery cell Ck may be discharged for a period of time until the pre-full-discharge capacity of each battery cell Cj is the same as the pre-full-discharge capacity of the reference battery cell Ck.

[0073] In addition, the control unit 115 may perform a process of matching the capacity of each battery cell at the time of full discharge when the lowest voltage among the voltages of each battery cell is within a predetermined range of full discharge. As a result, for example, when one or more battery cells are close to full discharge, a cell balancing process is performed, thereby further reducing the occurrence of battery cell over-discharge.

[0074] Figure 6 6 shows an example of transitions 601 to 603 of the charge rate of each of the battery cells C1, C2, Cn according to an embodiment. Figure 6 In the example of FIG. 1 , the process of step S101 is performed at a first time point t1 when the highest voltage among the voltages of each of the battery cells C1 to Cn is within a predetermined range on the fully charged side. Furthermore, the process from step S102 to step S106 described later is performed at a second time point t2 when the lowest voltage among the voltages of each of the battery cells C1 to Cn is within a predetermined range on the fully discharged side.

[0075] <Example of Matching the Capacity of Each Battery Cell at Full Charge and Discharge>

[0076] The control unit 115 may perform a process of matching the capacity of each battery cell when fully charged and a process of matching the capacity of each battery cell when fully discharged at different timings. As a result, for example, the capacity of each battery cell when fully charged and fully discharged can be matched, thereby reducing the possibility of overcharging and overdischarging of the battery cells.

[0077] In this case, for example, when the highest voltage among the voltages of each battery cell is within a predetermined range on the fully charged side, the control unit 115 may perform a process of matching the capacity of each battery cell at the time of full charge. In addition, when the lowest voltage among the voltages of each battery cell is within a predetermined range corresponding to the voltage at the time of full discharge, the control unit 115 may perform a process of matching the capacity of each battery cell at the time of full discharge.

[0078] Subsequently, the control unit 115 discharges each of the battery cells Cj other than the reference cell among the battery cells C1 to Cn (step S106). Here, for example, the control unit 115 can perform discharging to achieve cell balancing by opening the switch Sj for one or more battery cells Cj in the cell balancing section 111 for a period of time calculated as CBTime[j]. This allows, for example, the need for a cell balancing control command from the system side (the main body 20 side) to be eliminated, and cell balancing to be performed only on the battery pack 10 side. Furthermore, for example, cell balancing control can be performed without the user being aware, such as when the equipment 1 is in a long-term storage state of non-use. Furthermore, cell balancing control on the discharging side also becomes possible.

[0079] As is well known, the degradation speed of each cell can differ due to differences in the operating environment and variations in the manufacturing process. In this case, the capacity of each cell will differ. Even if the capacity of each cell is the same, the charge rate of each cell can differ. Therefore, even if cell balancing is performed to equalize the voltage of each cell, the capacity of the cells can not match. According to the present disclosure, even if the capacity and charge rate of each cell changes, more appropriate cell balancing control can be performed.

[0080] <Regarding the Control Unit 115>

[0081] Figure 7 is a diagram showing an example of the configuration of the control unit 115 according to the embodiment. In the example of Figure 7 The control unit 115 includes the processor 101, the memory 102, and the communication interface 103. These components can be coupled by a bus or the like. The memory 102 stores at least a portion of the program 104. The communication interface 103 includes an interface necessary for communication with other network elements.

[0082] At least part of the processes of the embodiments of the present disclosure is executed by the computer 100 when the program 104 is executed by cooperation of the processor 101 and the memory 102 and the like. The memory 102 can be any type. As a non-limiting example, the memory 102 can be a non-transitory computer readable storage medium. Furthermore, the memory 102 can be implemented using any appropriate 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, there can be several physically different memory modules in the computer 100. The processor 101 can be any type. The processor 101 can include one or more processors based on general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSP), and include, as a non-limiting example, multi-core processor architectures. The computer 100 can have multiple processors, such as an application-specific integrated circuit chip that is synchronized in time with a clock that is synchronized with a main processor.

[0083] The program can be stored and supplied to the computer using various types of non-transitory computer readable media. The non-transitory computer readable media include various types of tangible recording media. Examples of the non-transitory computer readable media include a magnetic recording medium, a magneto-optical recording medium, an optical disk medium, a semiconductor memory, and the like. The magnetic recording medium includes, for example, a floppy disk, a tape, a hard disk drive, and the like. The magneto-optical recording medium includes, for example, a magneto-optical disk, and the like. The optical disk medium includes, for example, a Blu-ray (registered trademark) disk, a CD (Compact Disc)-ROM (Read Only Memory), a CD-R (Recordable), a CD-RW (Rewritable), and the like. The semiconductor memory includes, for example, a solid state drive, a mask ROM, a PROM (Programmable ROM), an EPROM (Erasable PROM), a flash ROM, a RAM (Random Access Memory), and the like. Furthermore, the program can also be supplied to the computer through various types of transitory computer readable media. Examples of the transitory computer readable media include an electrical signal, an optical signal, and an electromagnetic wave. The transitory computer readable medium can supply the program to the computer via a wired communication path such as an electrical wire and an optical fiber, or via a wireless communication path.

[0084] In the above, the invention made by the inventor has been specifically described based on the embodiments, but the present invention is not limited to the embodiments that have been described, and various modifications can be made without departing from the gist thereof, needless to say.

Claims

1. A semiconductor device comprising: a voltage measurement circuit configured to measure a voltage of each of the first battery cell and the second battery cell coupled in series, a current measurement circuit configured to measure current flowing through the first battery cell and the second battery cell, and a control unit configured to control the discharge of at least one of the first battery cell and the second battery cell, wherein the control unit estimates a charge rate of each of the first battery cell and the second battery cell at the first time point based on a voltage 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 charge rate of each of the first battery cell and the second battery cell at a second time point different from the first time point based on a voltage of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at the second time point, calculating an integrated value of 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, estimating a maximum capacity of the first battery cell based on the charge rate of the first battery cell at the first time point, the charge rate of the first battery cell at the second time point, and the integrated value of the current, estimating a maximum capacity of the second battery cell based on the charge rate of the second battery cell at the first time point, the charge rate of the second battery cell at the second time point, and the integrated value of the current flowing through the second battery cell, determining a reference battery cell from among the first battery cell and the second battery cell based on the maximum capacity of the first battery cell, the charge rate of the first battery cell, the maximum capacity of the second battery cell, and the charge rate of the second battery cell, Battery cells other than the reference battery cell among the first battery cell and the second battery cell are discharged.

2. The semiconductor device according to claim 1 , wherein the control unit estimates the pre-full-charge capacity of the first battery cell based on the charge rate of the first battery cell and the estimated maximum capacity of the first battery cell, estimating a pre-full-charge capacity of the second battery cell based on the charge rate of the second battery cell and the estimated maximum capacity of the second battery cell, and A battery cell having the largest pre-full-charge capacity among the first battery cell and the second battery cell is determined as the reference battery cell.

3. The semiconductor device according to claim 2 , wherein the control unit discharges the battery cells other than the reference battery cell among the first battery cell and the second battery cell for a period of time until the pre-full-charge capacity of the battery cells is the same as the pre-full-charge capacity of the reference battery cell.

4. The semiconductor device according to claim 2 or 3, wherein when a lowest voltage among the voltages of the first battery cell and the second battery cell is within a predetermined range corresponding to a voltage at a time of full discharge, the control unit estimates the charge rate of each of the first battery cell and the second battery cell at the first time point, and When a highest voltage among the voltages of the first and second battery cells is within a predetermined range corresponding to a voltage at a full charge, the control unit estimates a charge rate of each of the first and second battery cells at the second time point.

5. A semiconductor device according to claim 2 or 3, wherein when the highest voltage among the voltages of the first battery cell and the second battery cell is within a predetermined range corresponding to the voltage when fully charged, the control unit discharges the battery cells among the first battery cell and the second battery cell except the reference battery cell.

6. The semiconductor device according to claim 1 , wherein the control unit estimates the capacity before full discharge of the first battery cell based on the charge rate of the first battery cell and the estimated maximum capacity of the first battery cell, and estimating a capacity before full discharge of the second battery cell based on the charge rate of the second battery cell and the estimated maximum capacity of the second battery cell, and The battery cell having the smallest pre-full-discharge capacity among the first battery cell and the second battery cell is determined as the reference battery cell.

7. The semiconductor device according to claim 6, wherein the control unit discharges the battery cells other than the reference battery cell among the first battery cell and the second battery cell for a period of time until the pre-full-discharge capacity of the battery cells is the same as the pre-full-discharge capacity of the reference battery cell.

8. A semiconductor device according to claim 6 or 7, wherein when the highest voltage among the voltages of the first battery cell and the second battery cell is within a predetermined range corresponding to the voltage when fully charged, the control unit estimates the charging rate of the first battery cell and the second battery cell at the first time point, and when the lowest voltage among the voltages of the first battery cell and the second battery cell is within a predetermined range corresponding to the voltage when fully discharged, the control unit estimates the charging rate of the first battery cell and the second battery cell at the second time point.

9. A semiconductor device according to claim 6 or 7, wherein when the lowest voltage among the voltages of the first battery cell and the second battery cell is within a predetermined range corresponding to the voltage when fully discharged, the control unit discharges the battery cells among the first battery cell and the second battery cell except the reference battery cell.

10. A method for controlling cell balance, comprising: measuring a voltage of each of the first and second battery cells coupled in series, measuring the current flowing through the first battery cell and the second battery cell, estimating a charge rate of each of the first battery cell and the second battery cell at the first time point based on a voltage of each of the first battery cell and the second battery cell measured at the first time point, estimating a charge rate of each of the first battery cell and the second battery cell at a second time point different from the first time point based on a voltage of each of the first battery cell and the second battery cell measured at the second time point, calculating an integrated value of 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, estimating a maximum capacity of the first battery cell based on the charge rate of the first battery cell at the first time point, the charge rate of the first battery cell at the second time point, and the integrated value of the current, estimating a maximum capacity of the second battery cell based on the charge rate of the second battery cell at the first time point, the charge rate of the second battery cell at the second time point, and the integrated value of the current; determining a reference battery cell from among the first battery cell and the second battery cell based on the maximum capacity of the first battery cell, the charge rate of the first battery cell, the maximum capacity of the second battery cell, and the charge rate of the second battery cell; Battery cells other than the reference battery cell among the first battery cell and the second battery cell are discharged.

11. The method for controlling cell balancing according to claim 10, wherein the step of determining the reference battery cell further comprises: estimating a pre-full-charge capacity of the first battery cell based on the charge rate of the first battery cell and the estimated maximum capacity of the first battery cell, estimating a pre-full-charge capacity of the second battery cell based on the charge rate of the second battery cell and the estimated maximum capacity of the second battery cell, and A battery cell having the largest pre-full-charge capacity among the first battery cell and the second battery cell is determined as the reference battery cell.

12. The method for controlling cell balancing according to claim 11 , wherein the step of discharging the battery cells other than the reference battery cell among the first battery cell and the second battery cell further comprises: The battery cell is discharged for a period of time until the pre-full-charge capacity of the battery cell is the same as the pre-full-charge capacity of the reference battery cell.

13. The method for controlling cell balancing according to claim 11 or 12, wherein When a lowest voltage among the voltages of the first battery cell and the second battery cell is within a predetermined range corresponding to a voltage at a time of full discharge, estimating the charge rate of each of the first battery cell and the second battery cell at the first time point is performed; and When a highest voltage among the voltages of the first battery cell and the second battery cell is within a predetermined range corresponding to a voltage at a full charge, estimating the charge rate of each of the first battery cell and the second battery cell at the second time point is performed.

14. The method for controlling cell balancing according to claim 11 or 12, wherein when a highest voltage among the voltages of the first battery cell and the second battery cell is within a predetermined range corresponding to a voltage at a full charge, a step of discharging battery cells other than the reference battery cell is performed.

15. The method for controlling cell balancing according to claim 10, wherein the step of determining the battery cell as the reference battery cell further comprises: estimating a capacity before full discharge of the first battery cell based on the charge rate of the first battery cell and the estimated maximum capacity of the first battery cell, and estimating a capacity before full discharge of the second battery cell based on the charge rate of the second battery cell and the estimated maximum capacity of the second battery cell, and The battery cell having the smallest pre-full-discharge capacity among the first battery cell and the second battery cell is determined as the reference battery cell.

16. The method for controlling control unit balancing according to claim 15, wherein the step of discharging the battery cells other than the reference battery cell among the first battery cell and the second battery cell continues for a period of time until the pre-full-discharge capacity of the battery cells is the same as the pre-full-discharge capacity of the reference battery cell.

17. A method for controlling cell balancing according to claim 15 or 16, wherein When the highest voltage among the voltages of the first battery cell and the second battery cell is within a predetermined range corresponding to a voltage at a fully charged state, performing a step of estimating a charge rate of the first battery cell and the second battery cell at the first time point, When a lowest voltage among the voltages of the first and second battery cells is within a predetermined range corresponding to a voltage at a full charge, estimating a charge rate of the first and second battery cells at the second time point is performed.

18. The method for controlling cell balancing according to claim 15 or 16, wherein when a lowest voltage is within a predetermined range corresponding to a voltage at a time of full discharge, a step of discharging the battery cells other than the reference battery cell among the first battery cell and the second battery cell is performed.

19. A battery pack comprising: a first battery cell and a second battery cell coupled in series, a voltage measurement circuit configured to measure a voltage of each of the first battery cell and the second battery cell, a current measurement circuit configured to measure current flowing through the first battery cell and the second battery cell, and a control unit configured to control the discharge of at least one of the first battery cell and the second battery cell, wherein the control unit estimates a charge rate of each of the first battery cell and the second battery cell at the first time point 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 time point, estimating a charge rate of each of the first battery cell and the second battery cell at a second time point different from the first time point based on a voltage of each of the first battery cell and the second battery cell measured by the voltage measurement circuit at the second time point, calculating an integrated value of 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, estimating a maximum capacity of the first battery cell based on the charge rate of the first battery cell at the first time point, the charge rate of the first battery cell at the second time point, and the integrated value of the current, estimating a maximum capacity of the second battery cell based on the charge rate of the second battery cell at the first time point, the charge rate of the second battery cell at the second time point, and the integrated value of the current, determining a reference battery cell from among the first battery cell and the second battery cell based on the maximum capacity of the first battery cell, the charge rate of the first battery cell, the maximum capacity of the second battery cell, and the charge rate of the second battery cell, and Battery cells other than the reference battery cell among the first battery cell and the second battery cell are discharged.

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