JP2010088194A - Device and method for adjusting capacity of battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately adjust the fluctuation in capacity occurring in a battery pack constituted of a cell containing a region less in the change rate of open voltage to capacity and having voltage-capacity characteristics. <P>SOLUTION: The capacity adjustment device 10 for the battery pack 1 having a plurality of cells 11n connected in series, the cells containing a first region less in the change rate of the open voltage to capacity and also having the voltage-capacity characteristics, the device includes a battery pack voltage sensor 103 for detecting the total voltage Vt of the battery pack 1, a cell voltage sensor 102 for detecting the terminal voltage Vcn of the cell 11n, a capacity adjustment part 101 for adjusting the capacity of each cell 11n, and a CPU 106 for controlling the operation of the capacity adjustment part 101. When the total voltage Vt belongs to a second region relatively greater in the change rate than the first region, the CPU 106 obtains the terminal voltage Vcn of the cell 11n, and calculates the time for operating the capacity adjustment part 101 based on the terminal voltage Vcn, to operate the capacity adjustment part 101 at the particular time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery pack capacity adjustment apparatus and method.

  If charging / discharging is repeated for an assembled battery in which a plurality of cells are connected in series, or if such an assembled battery is left for a long period of time, each of the cells constituting the assembled battery will be subject to a difference in self-discharge or deterioration. The cell has a variation in capacity (SOC). When the capacity varies among the cells, the usable power of the assembled battery is limited. For this reason, it is necessary to adjust the variation in the capacity generated in each cell as much as possible.

  2. Description of the Related Art Conventionally, a capacity adjustment method is known in which an open circuit voltage of each cell constituting an assembled battery is detected, a variation in capacity generated in each cell is estimated based on the open circuit voltage, and this is adjusted (Patent Document 1). ).

JP 2003-282155 A

  By the way, a cell having a voltage-capacitance characteristic including a region where a change rate of an open-circuit voltage with respect to a capacity is small is known as a cell constituting an assembled battery. When such a cell is charged, for example, in the vicinity of the start of charging (SOC: State of Charge (0%)), the cell voltage increases at a large rate of change, but the SOC decreases to, for example, about 20%. The cell voltage increase rate (rate of change) becomes dull after the point of time until the battery is charged. This tendency continues until the SOC before the full charge is about 95%, for example. Thereafter, in a short region before the SOC reaches 100%, the cell voltage increases at a relatively large rate of change and reaches full charge. This tendency is also true when the cell is discharged. That is, when this type of cell is charged / discharged, the SOC is within a predetermined interval (for example, about 20% to about 95%) from the time of full charge to the time of completion of discharge or from the time of charge start to the time of completion of charge. The change profile of the cell voltage becomes substantially flat in a wide area.

  Moreover, the voltage sensor used at the time of open circuit voltage detection by the conventional method mentioned above may produce an error in the detected voltage value from the limit of decomposition performance.

  Therefore, when the technique of Patent Document 1 is applied to an assembled battery in which a plurality of cells having the above-described characteristics are connected in series, and the detected open-circuit voltage of the cell belongs to the above-described substantially flat region, the open-circuit voltage is set. The accuracy of the capacity estimated based on this becomes a problem.

  The problem to be solved by the present invention is to provide an assembled battery capacity adjusting apparatus and method capable of accurately adjusting a variation in capacity generated in an assembled battery composed of cells having predetermined voltage-capacitance characteristics. It is.

  When adjusting the capacity of an assembled battery composed of cells having a predetermined voltage-capacitance characteristic, the present invention provides a terminal for each cell when the total voltage of the assembled battery belongs to a region where the change rate of the open-circuit voltage with respect to the capacity is large. The above-described problem is solved by obtaining a voltage, calculating a time for operating the cell capacity adjusting means provided for each cell based on the terminal voltage of the cell, and operating the cell capacity adjusting means for the time. .

  According to the above invention, when the total voltage of the assembled battery belongs to a region where the change rate of the open circuit voltage with respect to the capacity is large, the cell capacity adjusting means is operated for a time calculated based on the terminal voltage of each cell. It is possible to accurately adjust the variation in capacity generated in the assembled battery including cells having voltage-capacity characteristics.

  Hereinafter, embodiments of the invention will be described with reference to the drawings.

  In addition, although the following description demonstrates as what the assembled battery is comprised with the lithium ion battery, it is not limited to this. In addition, this assembled battery will be described as being mounted on a vehicle.

  As shown in FIG. 1, the capacity adjustment system 100 according to the present embodiment includes an assembled battery 1, a current sensor 2, a main relay 3, an inverter 4, a motor 5, and a capacity adjustment device 10.

  The assembled battery 1 is connected to the inverter 4 via the current sensor 2 and the main relay 3 and supplies DC power to the inverter 4. The current sensor 2 detects a discharge current flowing from the assembled battery 1 to the inverter 4 and a charging current flowing from the inverter 4 to the assembled battery 1, and outputs them to the battery controller 104 (CPU 106) of the capacity adjustment device 10. The main relay 3 is opened / closed by a command from the CPU 106 of the capacity adjustment device 10 to connect and release the assembled battery 1 and the motor 5. The inverter 4 converts the DC power of the assembled battery 1 into AC power and applies the AC power to the motor 5, and drives the motor 5 to run the vehicle. The inverter 4 also converts AC regenerative power generated by the motor 5 during braking of the vehicle into DC power and charges the assembled battery 1. The motor 5 is composed of an AC motor for driving.

  The assembled battery 1 of this example is composed of a set of series cell blocks in which 96 cells (unit batteries) 11 as secondary batteries are connected in series. However, the number of series connections of the assembled battery 1 is not limited to 96. Moreover, the assembled battery 1 may be comprised by the serial-parallel cell block which connected the serial cell block mentioned above in parallel by arbitrary numbers.

  Each of the cells 111 to 1196 in this example (hereinafter also referred to as “11n” as a representative. “N” means the nth cell 11) is composed of a lithium ion battery having the same design. Hereinafter, an example of the structure of each cell 11n will be described.

  As shown in FIG. 2, the cell 11 n of this example includes a battery element 250, an outer case 260, a positive electrode lead (positive electrode terminal) 270, and a negative electrode lead (negative electrode terminal) 280.

  The battery element 250 includes a positive electrode plate having a positive electrode active material layer 251 on a current collector 252 and a negative electrode plate having a negative electrode active material layer 253 on a current collector 252. A separator (electrolyte layer) 254 that holds an electrolyte. It is comprised by laminating | stacking via.

The positive electrode active material layer 251 includes a positive electrode active material, a conductive additive, a binder, and the like. Examples of the positive electrode active material include lithium-transition metal composite oxides such as LiMn ₂ O ₄ . Examples of the conductive assistant include acetylene black, carbon black, graphite, carbon fiber, and carbon nanotube. Examples of the binder include polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), and polyimide.

  The negative electrode active material layer 253 includes a negative electrode active material, a conductive additive, a binder, and the like. The negative electrode active material includes a graphite-based carbon material (graphite-based). Since the cell 11n of this example includes the battery element 250 having the negative electrode active material layer 253 including the graphite-based carbon material, the cell 11n has the voltage-SOC characteristics shown in FIG. This point will be described later.

  The current collector 252 is, for example, an aluminum foil, a copper foil, a stainless steel foil, a titanium foil, a nickel-aluminum clad material, a copper-aluminum clad material, a stainless steel-aluminum clad material, or a plating material of a combination of these metals. Etc. Among the above materials, a positive electrode current collector 252 is selected as a positive electrode potential, and a negative electrode current collector 252 is selected from a material that is stable at a negative electrode potential. Generally, the positive electrode current collector 252 is made of aluminum. A copper foil is used for the negative electrode current collector 252.

  The separator 254 plays a role of holding an electrolyte, and is made of, for example, polyolefin such as polyethylene or polypropylene, polyamide, polyimide, or the like.

The electrolyte (electrolytic solution) held in the separator 254 is a liquid polymer or a fluid gel polymer, and includes, for example, an organic solvent, a supporting salt, a small amount of a surfactant, and the like. Examples of the organic solvent include cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC), chain carbonates such as dimethyl carbonate, and ethers such as tetrahydrofuran. Examples of the supporting salt include inorganic acid anion salts such as lithium salt (LiPF ₆ ) and organic acid anion salts such as LiCF ₃ SO ₃ . The gel polymer electrolyte includes an electrolytic solution, a host polymer, and the like. As the host polymer, a polymer having no lithium ion conductivity, such as a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVDF-HFP), PAN (polyacrylonitrile (PAN), PMMA (polymethyl methacrylate (PMMA)), Examples thereof include polymers (solid polymer electrolytes) having ion conductivity such as PEO (polyethylene oxide) and PPO (polypropylene oxide).

  The exterior case 260 is formed in a bag shape by joining the peripheral edges of the sheet-shaped exterior material 262 by heat welding, and is used to accommodate the battery element 250. The exterior material 262 is, for example, a polymer-metal composite laminate film having a three-layer structure, and includes a metal layer 264 and a polymer resin layer 266 disposed on both surfaces of the metal layer 264. The metal layer 264 can be made of, for example, a metal foil such as aluminum, stainless steel, nickel, or copper. The polymer resin layer 266 can be composed of, for example, a heat-welding resin film such as polyethylene, polypropylene, modified polyethylene, modified polypropylene, ionomer, and ethylene vinyl acetate. Note that the bonding of the exterior material 262 is not limited to applying heat welding.

  The positive electrode lead 270 and the negative electrode lead 280 are connected to the current collector 252 of the battery element 250 and extend from the inside of the outer case 260 to the outside in order to draw current from the battery element 250.

<Capacity adjustment device>
Returning to FIG. 1, the capacity adjustment apparatus 10 of this example is an apparatus that adjusts the capacity of the assembled battery 1 connected to the motor 5 via the current sensor 2, the main relay 3, and the inverter 4, and includes a capacity adjustment unit. 101, a cell voltage sensor 102, an assembled battery voltage sensor 103, and a battery controller 104.

  The battery controller 104 includes a CPU 106, a ROM 107, and a RAM 108. The CPU 106 (control unit) executes processing (capacity adjustment processing) described later. The ROM 107 stores a program executed by the CPU 106. The RAM 108 (storage means) temporarily stores predetermined data. The RAM 108 includes at least information related to the voltage-SOC correlation diagram (see FIG. 3) of the assembled battery 1 and the cell 11n, the threshold voltage value C1 of the cell 11n, and the C1 multiplied by the number of cells. Information regarding the threshold voltage value 96C1 and information regarding the capacity adjustment time initial value t0 (seconds) are stored in advance.

  The assembled battery voltage sensor 103 (total voltage detection means) detects the total voltage Vt of the assembled battery 1, that is, the terminal voltage of the entire assembled battery 1, and outputs it to the CPU.

  After receiving a command from the CPU 106, the cell voltage sensor 102 (cell voltage detection means) is connected to terminal voltages Vc1 to Vc96 (hereinafter also referred to as Vcn as representative. Vcn represents the voltage of the nth cell 11). It is detected and output to the CPU 106. In this example, when the total voltage Vt of the assembled battery 1 belongs to the A region (see FIG. 3) described later, the cell voltage sensor 102 does not detect the terminal voltage Vcn of each cell 11n, and the B region (see FIG. 3). The voltage Vcn is detected when belonging to.

  The capacity adjusting unit 101 (capacity adjusting means) configures the assembled battery 1 in order to prevent any of the cells 11n from being overcharged or overdischarged and the capacity of the assembled battery 1 from being fully utilized. The variation of the capacity (SOC) generated in each cell 11n is adjusted for each cell 11n. In general, in order to adjust the variation of the SOC generated in each cell 11n, a cell 11n having a larger SOC than the cell 11n having a predetermined SOC is discharged and leveled, and a cell 11n having a smaller SOC is charged. Leveling. In this example, a case where a cell 11n having a large SOC is discharged is illustrated.

  The capacity adjustment unit 101 of this example is a circuit for discharging the SOC of each cell 11n, and includes a series circuit of a resistor 101a and a transistor 101b. This series circuit is connected in parallel to each cell 11n. The resistor 101a is a discharge resistor, and the transistor 101b is a switching element for discharging and stopping. As the switching element, a semiconductor switching element such as an FET, a relay, or the like can be used instead of the transistor 101b.

  The capacity adjustment device 10 may further include a temperature sensor 109 and the like. In this case, the temperature sensor 109 detects the temperature of the assembled battery 1 and outputs it to the CPU 106.

  The cell 11n when the negative electrode active material layer 253 (see FIG. 2) contains a graphite-based carbon material has voltage-SOC characteristics as shown in FIG. 3, for example. In FIG. 3, the horizontal axis indicates the capacity (SOC) of the cell, and the vertical axis indicates the open circuit voltage of the cell. In order to obtain the characteristics shown in FIG. 3, for example, the cell voltage at full charge is first detected. Next, the cell is discharged with a predetermined current. At this time, discharge is stopped at each time point when the SOC of the cell is reduced by, for example, a predetermined percentage in the calculation, and the cell voltage at that time is detected. By repeating this, the characteristics shown in FIG. 3 can be acquired.

  In general, in an assembled battery in which the SOC of a cell is in a fixed proportional relationship with the open circuit voltage, the open circuit voltage variation itself is a variation in capacity generated in each cell. However, as shown in FIG. 3, since the cell 11n of the present embodiment uses a graphite-based carbon material for the negative electrode, the change amount of the open circuit voltage with respect to the SOC standard change width, that is, the change rate of the open circuit voltage with respect to the SOC ( Compared to the case of the B region (second region, a narrow region with an SOC of about 20% or less) and the C region (second region, a narrow region with an SOC of about 95% or more) In addition, it becomes smaller in the case of the A region (first region, a wide region from about 20% to about 95% SOC).

  In the example of FIG. 3, even if the SOC fluctuates by about 75% in the A region, the change amount ΔVcna of the open circuit voltage is extremely small. As described above, when the detected open voltage is within the A region with respect to the cell 11n having a flat voltage waveform in which the cell voltage hardly changes in the wide SOC region (A region), the cell voltage sensor 102 (set) It is difficult to accurately calculate the capacity (SOC) of the cell 11n (the assembled battery 1) at that time from the resolution limit of the battery voltage detection sensor 103).

  In the example of FIG. 3, it is understood that the change amount ΔVcnb of the open circuit voltage is large (ΔVcnb >> ΔVcna) even if the SOC fluctuates by only about 20% in the B region. In the present embodiment, when the total voltage Vt belonging to a region (B region or C region, preferably B region) in which the slope of the voltage waveform in FIG. 3 is large, in other words, the change rate of the open-circuit voltage with respect to the SOC is large is detected. For example, the terminal voltage Vcn of each cell 11n is detected, the capacity adjustment time tcn (first time) for each cell 11n is calculated based on this Vcn, and this tcn is used as the capacity adjustment time initial value t0 (second time). Rewrite (update) for (time).

<Capacity adjustment process>
Hereinafter, an example of the capacity adjustment process according to the present embodiment will be described.

  As shown in FIG. 4, first, in step (hereinafter, step is abbreviated as S) 1, the assembled battery voltage sensor 103 detects the total voltage Vt of the assembled battery 1 and outputs it to the CPU 106. The detection timing of the total voltage Vt is not particularly limited. For example, the ignition key switch (IGN) (not shown) may be turned on (when the vehicle is started), may be turned off (when the vehicle is stopped), or may be turned off after the IGN is turned on. Until the vehicle is running (during vehicle travel).

  Next, in S <b> 2, the CPU 106 acquires the threshold voltage value 96 </ b> C <b> 1 of the assembled battery 1 stored in the RAM 108. The threshold voltage value 96C1 acquired here is a voltage value belonging to the B region of FIG. 3, that is, the region where the change rate of the open circuit voltage with respect to the SOC is large.

  Next, in S3, the CPU 106 compares the total voltage Vt of the assembled battery 1 detected in S1 with the threshold voltage value 96C1 acquired in S2. As a result, if Vt> 96C1 (No in S3), the process proceeds to S10, and if Vt ≦ 96C1 (Yes in S3), the process proceeds to S4.

  If the total voltage Vt of the detected assembled battery 1 is within the area A in FIG. 3 even if S5 to S9 described later are executed in the case of No in S3, as described above, the assembled battery voltage sensor 103 From the limit of resolution, it is difficult to accurately calculate the capacity of the assembled battery 1 as a whole. Normally, it takes a relatively long time (for example, about 1 minute for 96 cells) to detect all the terminal voltages Vcn of each cell 11n by the cell voltage sensor 102, and the capacity of the assembled battery 1 is accurately determined for the reason described above. It is useless to detect the terminal voltage Vcn of each cell 11n in spite of being difficult to calculate. Therefore, in the case of No in S3, the process proceeds to S10.

  Next, in S <b> 4, the cell voltage sensor 102 detects the terminal voltage Vcn of each cell 11 n and outputs it to the CPU 106. The acquisition order of the cell voltage Vcn is not particularly limited, and the acquisition order may be determined and acquired one by one, or the voltages of all the cells 11n may be acquired simultaneously.

  Next, in S5, the CPU 106 extracts the cell voltage minimum value Vcmin from the cell voltage Vcn for each cell 11n acquired in S4, and sets this as the capacity adjustment target value Vg. Thereafter, a capacity adjustment time tcn (seconds) corresponding to the deviation between the set capacity adjustment target value Vg and the voltage Vcn of each cell 11n is calculated, and the capacity adjustment unit 101 is turned on for the above-mentioned adjusted discharge time tcn to adjust the capacity. The cell 11n having a voltage Vcn larger than the target value Vg is discharged. An example (after S6) is as follows.

  In S6, CPU 106 calculates a difference ΔVcn (= Vcn−Vg) between cell voltage Vcn acquired in S4 and capacity adjustment target value Vg set in S5.

  For example, in the example shown in FIG. 5, Vcmin is indicated by the Vc4 cell (fourth cell 114), the next highest voltage is the Vc1 cell (first cell 111), and thereafter the Vc2 cell ( The second cell 112) and the Vc3 cell (third cell 113) are in this order. Then, ΔVc1 of the cell 111 is (Vc1−Vc4), ΔVc2 of the cell 112 is (Vc2−Vc4), and ΔVc3 of the cell 113 is (Vc3−Vc4).

  Next, returning to FIG. 4, in S7, the CPU 106 determines each cell 11n other than the cell indicating the cell voltage minimum value Vcmin extracted in S5 based on ΔVcn calculated in S6 (in the example of FIG. 5, other than the cell 114). The capacity adjustment amount ΔSOCn of each of the cells 111 to 113, 115 to 1196) is calculated. The calculation of ΔSOCn of each cell 11n can be performed based on the cell voltage-SOC correlation diagram (see FIG. 3) stored in the RAM.

  Next, in S8, CPU 106 calculates a capacity adjustment time tcn for each cell for each cell other than the specific cell based on ΔSOCn calculated in S7. Since the capacity adjustment amount ΔSOCn can be considered in the same manner as the electric amount ΔQn (unit is C) for each cell 11n, tcn for each cell is calculated based on Equation 1.

[Formula 1] ΔQn = Ic × tcn (1)
Here, “Ic” indicates a current (unit: A) discharged through the resistor 101a. For example, in the example of FIG. 5, a capacity adjustment time tc1 that discharges (discharges) electricity by ΔQ1 is calculated for the cell 111, tc2 that discharges ΔQ2 is calculated for the cell 112, and the cell 113 Is calculated by calculating tc3 which discharges ΔQ3. As a result, tc1 of the cell 111 is calculated as (ΔQ1 / Ic), tc2 of the cell 112 is calculated as (ΔQ2 / Ic), and tc3 of the cell 113 is calculated as (ΔQ3 / Ic).

  Next, returning to FIG. 4, in S9, the CPU 106 rewrites the capacity adjustment time initial value t0 stored in the RAM 108 to the capacity adjustment time tcn calculated in S8.

  Next, in S10, the CPU 106 stores the capacity adjustment time stored in the RAM 108 (for example, the initial value t0 if No in S3, the rewritten value tcn rewritten in S9 if Yes in S3). To get.

  Based on the acquisition or storage (initial value or previous value) in S10, the capacity adjustment of each cell is executed, but the actual execution timing of the capacity adjustment is performed at predetermined intervals (for immediate execution after update). Not limited).

  The predetermined cycle is executed every predetermined time and every predetermined charge / discharge amount integrated value (charging and discharging are counted as integration). This is because the estimated variation is caused by the internal resistance and is reproduced every predetermined period.

  Thereby, even if it is a case of NO determination in S3, the capacity can be adjusted with the initial value or a close estimated value (previous value). Next, when it is No at S3, the CPU 106 determines the capacity adjustment unit 101 of each cell 11n, and when it is Yes at S3, it determines the capacity adjustment unit 101 of cells other than the specific cell. A command signal is sent to the base of the transistor 101b to turn on the transistor 101b for the acquired capacitance adjustment time (t0 or tcn) and to turn it off (non-conducting) after a predetermined time.

  In response to a command from the CPU 106, the capacity adjustment unit 101 turns on the transistor 101b for a predetermined time. As a result, the charging power of the designated cell 11n is discharged through the resistor 101a, and the SOC of the designated cell 11n is reduced by the amount of discharge. In this case, the CPU 106 performs duty control by repeatedly turning on and off the transistor 101b. This duty ratio is determined based on the discharge capacity and discharge time (capacity adjustment time) of the designated cell 11n.

  A voltage sensor (not shown) is connected between the collector and emitter of the transistor 101b. When the transistor 101b is turned on, the collector-emitter voltage becomes approximately 0V, and when the transistor 101b is turned off, the collector-emitter voltage becomes the cell voltage Vcn of each cell 11n. The CPU 106 monitors the collector-emitter voltage of the transistor 101b with a voltage sensor (not shown), and checks the operation status of the transistor 101b, that is, the capacity adjustment status of each cell 11n, and observes the variation in the SOC generated between the cells 11n. adjust.

  From FIG. 6, by discharging only during tc1 with respect to the cell 111, only during tc2 with respect to the cell 112, and only during tc3 with respect to the cell 113, the SOCs of the cells 111 to 113 become ΔQ1 , ΔQ2 and ΔQ3 are understood to decrease. The voltages Vc1, Vc2, and Vc3 of the cells 111 to 113 are finally adjusted to the vicinity of the same voltage Vc4 (Vcmin) as that of the cell 114.

  As described above, according to the present embodiment, the CPU 106 adds the total assembled voltage 1 to the B region (see FIG. 3) which is relatively larger than the A region (see FIG. 3) where the rate of change of the voltage with respect to the SOC is small. After the terminal voltage Vcn of each cell 11n is acquired when the voltage Vt belongs, the minimum voltage value Vc4 is acquired from the terminal voltage Vcn, and thereafter, other than the cell 114 indicating the minimum voltage value Vc4 and the minimum voltage value Vc4 Since the capacity adjustment unit 101 is operated only for the times tc1 to tc3 and tc5 to tc96 calculated based on the terminal voltages Vc1 to Vc3 and Vc5 to Vc96 of the respective cells 111 to 113 and 115 to 1196 of FIG. 3), the variation in capacity generated in the assembled battery 1 composed of the cells 11n having the voltage-capacitance characteristics including the voltage-capacitance characteristics can be accurately adjusted.

FIG. 1 is a block diagram showing an example of an assembled battery capacity adjustment system according to the present embodiment. FIG. 2 is a cross-sectional view showing an example of a cell constituting the assembled battery of FIG. FIG. 3 is a characteristic diagram showing the relationship between the voltage (V) and SOC (%) of the assembled battery of FIG. 1 and the cell of FIG. FIG. 4 is a flowchart illustrating an example of the capacity adjustment process according to the present embodiment. FIG. 5 is a partially enlarged view of a portion V in FIG. FIG. 6 is an explanatory diagram showing the transition of the cell voltage before and after capacity adjustment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Capacity adjustment system 1 ... Battery assembly 111-1196 (11n) ... Cell 2 ... Current sensor 3 ... Main relay 4 ... Inverter 5 ... Motor 10 ... Capacity adjustment apparatus 101 ... Capacity adjustment part (capacity adjustment means)
101a ... resistor 101b ... transistor 102 ... cell voltage sensor (cell voltage detection means)
103 ... Battery voltage sensor (battery voltage detection means)
104 ... Battery controller 106 ... CPU (control means)
107 ... ROM
108 ... RAM (storage means)
109 ... temperature sensor

Claims (6)

An apparatus for adjusting the capacity of an assembled battery in which a plurality of cells having voltage-capacitance characteristics including a first region in which a change rate of an open-circuit voltage with respect to a capacity is small is connected,
A total voltage detecting means for detecting a total voltage which is a terminal voltage of the whole assembled battery;
Cell voltage detecting means for detecting a terminal voltage of the cell;
Cell capacity adjusting means for adjusting the capacity of each cell;
Control means for controlling the operation of the cell capacity adjusting means,
The control means obtains a terminal voltage of the cell when the total voltage belongs to a second region where the rate of change is relatively larger than the first region, and based on the terminal voltage of the cell A battery pack capacity adjustment device characterized in that a time for operating the cell capacity adjustment means is calculated and the cell capacity adjustment means is operated for the time. The capacity adjustment device for an assembled battery according to claim 1,
The control means acquires a minimum voltage value from the acquired terminal voltage of the cell, and calculates the time based on the minimum voltage value and the terminal voltage of the cell. apparatus. The capacity adjustment device for an assembled battery according to claim 1 or 2,
The battery is a lithium-ion battery including a battery element having a negative electrode active material layer containing a graphite-based carbon material. A method of adjusting the capacity of an assembled battery in which a plurality of cells having voltage-capacitance characteristics including a first region in which a change rate of an open circuit voltage with respect to a capacity is small is connected,
Obtaining a terminal voltage of the cell when a total voltage which is a terminal voltage of the entire assembled battery belongs to a second region where the rate of change is relatively larger than the first region;
Calculating a first time for operating a cell capacity adjusting means for adjusting the capacity of each cell based on the terminal voltage of the cell;
And a step of operating the cell capacity adjusting means only for the first time. A method for adjusting the capacity of an assembled battery according to claim 4,
After calculating said 1st time, the capacity | capacitance adjustment method of the assembled battery characterized by rewriting the 2nd time previously memorize | stored in the memory | storage means to the said 1st time. The battery pack capacity adjustment method according to claim 5,
The assembled battery capacity adjusting method, wherein when the total voltage belongs to the first area, the cell capacity adjusting means is operated only for the second time.

Images