JP2013250071A - Full charge capacity detection device and storage battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and highly accurately detect a full charge capacity on the basis of ΔSOC.SOLUTION: An estimated capacity value (FCC) that is an estimate value of a full charge capacity of a battery module is obtained by dividing an integration quantity (ΣI) of a current flowing the battery module by a variation (ΔSOC) of SOC (State of Charge) of the battery module. Further, reliability (W) of the estimation is obtained for every estimated capacity value by using the variation of SOC. An output capacity value (FCC) that is a detection value of the full charge capacity is obtained by weighing and averaging the plurality of estimated capacity values using the plurality of degrees of reliability corresponding to the plurality of estimated capacity values.

Description

  The present invention relates to a full charge capacity detection device and a storage battery system.

  There is known a method of detecting the full charge capacity of a battery module by dividing the integrated amount of current flowing through the battery module composed of a storage battery by the amount of change in the SOC (state of charge) of the battery module. In this method, when ΔSOC (the amount of change in SOC) is small, the influence of an error included in the current measurement value of the battery module increases, and the detection accuracy of the full charge capacity decreases. For example, as shown in FIG. 12, there is a usage form in which charge / discharge for so-called peak shift is performed in normal times while securing a certain remaining capacity in preparation for a power failure. There is a high possibility that ΔSOC in the discharge is not sufficiently large.

  In order to improve the detection accuracy of the full charge capacity, in the first conventional method, when the full charge capacity is detected, the discharge exceeds the SOC lower limit value in the normal use state, and then the charge exceeds the SOC upper limit value. By doing so, ΔSOC is expanded (see Patent Document 1 below). In the second conventional method, when ΔSOC is smaller than a predetermined value, detection of the full charge capacity is not executed (see Patent Document 2 below).

JP 2012-29455 A JP 2011-106953 A

  The first conventional method cannot be used for a usage pattern that cannot allow discharge exceeding the SOC lower limit value or charging exceeding the SOC upper limit value (for example, a usage pattern as shown in FIG. 12), and discharge exceeding the SOC lower limit value. Alternatively, normal use of the battery module is restricted during the charging period exceeding the SOC upper limit value. Further, in the second conventional method, when the state where ΔSOC is smaller than a predetermined value continues, the full charge capacity detection cannot be executed continuously. In the usage pattern as shown in FIG. 12, in particular, a state where ΔSOC falls below a predetermined value may occur continuously or frequently.

  Therefore, an object of the present invention is to provide a full charge capacity detection device and a storage battery system that can detect a full charge capacity stably and accurately.

  A full charge capacity detection device according to the present invention is based on a remaining capacity change amount of a battery module made of a storage battery during a target period and an integrated amount of current flowing through the battery module during the target period. A full charge capacity estimation unit that generates an estimated capacity value by estimating a full charge capacity, a reliability derivation unit that obtains a reliability of the estimated capacity value based on the remaining capacity change amount, and a plurality of timings And an output processing unit that generates an output capacity value of the full charge capacity based on a plurality of estimated capacity values and a plurality of reliability levels corresponding to the plurality of estimated capacity values.

  A storage battery system according to the present invention includes a battery module including a storage battery, and the above-described full charge capacity detection device that detects a full charge capacity of the battery module.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the full charge capacity detection apparatus and storage battery system which can detect a full charge capacity stably accurately.

1 is a schematic overall configuration diagram of a storage battery system according to a first embodiment of the present invention. It is an internal block diagram of the full charge capacity detection apparatus which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the estimation method of a full charge capacity. It is a figure which shows the waveform of the measured current value of a battery module, the estimated value of SOC, the estimated value of full charge capacity, and the output value of full charge capacity. It is a partial block diagram of a full charge capacity detection apparatus including the internal block diagram of a FCC statistics processing part. It is a figure which shows the corresponding relationship with the remaining capacity variation | change_quantity, estimated capacity | capacitance value, and reliability which are calculated | required sequentially, and each time. It is a flowchart showing the operation | movement procedure of FCC statistical processing. It is a figure which concerns on 2nd Embodiment of this invention and shows the equivalent circuit of a battery module. It is a figure for demonstrating the open circuit voltage estimation method which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the parameter utilized in 4th Embodiment of this invention. It is a figure for demonstrating the output adjustment process which concerns on 7th Embodiment of this invention and sets the update restriction | limiting range. It is a figure which shows the mode of the fluctuation | variation of SOC in a certain usage form.

  Hereinafter, an example of an embodiment of the present invention will be specifically described with reference to the drawings. In each of the drawings to be referred to, the same part is denoted by the same reference numeral, and redundant description regarding the same part is omitted in principle. In this specification, for simplification of description, a symbol or reference that refers to information, signal, physical quantity, state quantity, member, or the like is written to indicate information, signal, physical quantity, state quantity or Names of members and the like may be omitted or abbreviated.

<< First Embodiment >>
A first embodiment of the present invention will be described. FIG. 1 is a schematic overall configuration diagram of a storage battery system 1 according to the first embodiment of the present invention. The storage battery system 1 includes a battery module 11, a current sensor 12, a voltage sensor 13, a temperature sensor 14, and a battery control unit 15. You may think that the electric power block 20 is also contained in the component of the storage battery system 1. FIG.

  The battery module 11 includes one or more storage batteries (in other words, secondary batteries). The storage battery forming the battery module 11 is any type of storage battery, for example, a lithium ion battery or a nickel metal hydride battery. In FIG. 1, the battery module 11 is formed by a plurality of storage batteries connected in series, but the number of storage batteries forming the battery module 11 may be one. Some or all of the storage batteries included in the battery module 11 may be connected in parallel to each other. Hereinafter, the battery module 11 is considered as one storage battery. In the present embodiment, discharging and charging means discharging and charging of the battery module 11 unless otherwise specified.

  A power block 20 is connected to the battery module 11. The power block 20 includes a load and a power source. The battery module 11 can supply discharge power to a load in the power block 20 and can be supplied with charging power from a power source in the power block 20. A power conversion circuit (not shown) may be interposed between the battery module 11 and the load and power source in the power block 20.

  The current sensor 12 is interposed between the battery module 11 and the power block 20 and measures the value of current flowing through the battery module 11 (hereinafter also referred to as battery current value). The battery current value measured by the current sensor 12 is represented by the symbol I. The voltage sensor 13 measures the value of the output voltage of the battery module 11 (hereinafter also referred to as a battery voltage value). The battery voltage value measured by the voltage sensor 13 is represented by the symbol CCV. The battery voltage value CCV is a terminal voltage value of the battery module 11 and a potential difference between the positive electrode and the negative electrode of the battery module 11. The temperature sensor 14 measures the temperature of the battery module 11 (hereinafter referred to as battery temperature). The battery temperature measured by the temperature sensor 14 is represented by the symbol T. The battery temperature T is, for example, the surface temperature of the pack that encloses the storage battery in the battery module 11 or the temperature at a specific part in the battery module 11.

  The battery current value I, the battery voltage value CCV, and the battery temperature T measured by the sensors 12, 13, and 14 are sent to the battery control unit 15. The battery control unit 15 controls charging and discharging of the battery module 11 using battery state data including the battery current value I, the battery voltage value CCV, and the battery temperature T.

The battery control unit 15 includes a full charge capacity detection device 30. The full charge capacity detection device 30 detects the full charge capacity of the battery module 11 based on the battery current value I, the battery voltage value CCV, and the battery temperature T. The detection value of the full charge capacity by the full charge capacity detection device 30 is represented by the symbol FCC _OUT .

  FIG. 2 shows an internal block diagram of the full charge capacity detection device 30. Hereinafter, the battery current value I, the battery voltage value CCV, and the battery temperature T measured by the sensors 12, 13, and 14 may be referred to as a measured current value I, a measured voltage value CCV, and a measured temperature T. Sometimes called measured values I, CCV and T.

The full charge capacity detection device 30 includes an OCV estimation unit 31 that estimates the open circuit voltage OCV of the battery module 11 using all or a part of the measurement values I, CCV, and T, and an estimated value of the open circuit voltage OCV by the OCV estimation unit 31. , An SOC estimation unit 32 that estimates an SOC (state of charge) that is a remaining capacity index of the battery module 11, a current integration unit 33 that calculates a current integration amount ΣI by integrating the measured value I, and an FCC estimation unit 35. A flag storage unit 34 that holds and stores an FCC estimation execution flag FLG for controlling execution / non-execution of the FCC estimation process by 35, and an estimation result of the SOC estimation unit 32 when the flag FLG is set to “ON” And the FCC estimation unit 35 that estimates the full charge capacity FCC of the battery module 11 using the current integration result of the current integration unit 33, and the statistical processing data. Comprises a FCC statistical processing section 36 for calculating and outputting a detection value FCC _OUT of full charge capacity using the estimated results of the FCC estimation unit 35, a statistical processing data storage unit 37 for holding and storing the statistical process data, the . Hereinafter, the operation, function, and configuration of each part illustrated in FIG. 2 will be described in detail. In the following description, the open circuit voltage, the full charge capacity, the remaining capacity, and the SOC refer to those of the battery module 11 unless otherwise specified.

The OCV estimation unit 31 estimates the open circuit voltage OCV based on the measured voltage value CCV when the charging and discharging of the battery module 11 is stopped, and when the open circuit voltage OCV is estimated, the FCC estimation execution flag FLG is “ON”. Set. More specifically, for example, when a predetermined fixed time (for example, 1 hour) has elapsed since the switching from the charge / discharge execution state to the charge / discharge stop state, the OCV estimation unit 31 determines the measured voltage value CCV as the voltage sensor 13. The obtained measured voltage value CCV is estimated and derived as the value of the open circuit voltage OCV, and the flag FLG is set to “ON”. The OCV estimation unit 31 may change the certain time according to the measured temperature T. The charge / discharge execution state refers to a state where the battery module 11 is being charged or discharged, and corresponds to a state where the absolute value of the measured current value I is greater than a predetermined value _ITH , for example. The charge / discharge stop state refers to a state where charging and discharging of the battery module 11 are stopped, and corresponds to a state where the absolute value of the measured current value I is equal to or less than a predetermined value _ITH , for example. The predetermined value I _TH may be zero or a minute positive value. The OCV estimation unit 31 can determine the estimation timing of the open circuit voltage OCV based on the measured current value I or based on the state of the switching element that switches between the charge / discharge execution state and the charge / discharge stop state.

  The SOC of the battery module 11 is a ratio of the remaining capacity of the battery module 11 to the full charge capacity of the battery module 11 and depends on the open circuit voltage OCV of the battery module 11. The SOC estimation unit 32 holds table data or an arithmetic expression that defines the relationship between the open circuit voltage OCV of the battery module 11 and the remaining capacity index SOC. The SOC estimation unit 32 converts the estimated value of the open circuit voltage OCV by the OCV estimation unit 31 into the remaining capacity index SOC of the battery module 11 using the table data or the arithmetic expression.

  The current integrating unit 33 integrates the measured current value I during an arbitrary period, and calculates and outputs the integrated value as a current integrated amount ΣI. A period during which this integration is performed is called a target period. It is assumed that the polarity of the battery current value I when the battery module 11 is discharged is negative, and the polarity of the battery current value I when the battery module 11 is charged is positive.

  The flag storage unit 34 is formed of a semiconductor memory or the like, and stores and holds the state of any flag including the flag FLG. The flag FLG is set to “ON” or “OFF”.

  The FCC estimation unit 35 executes an FCC estimation process for estimating the full charge capacity FCC of the battery module 11 when the flag FLG is set to “ON”. When “ON” is set in the flag FLG, the FCC statistical processing unit 36 also executes subsequent FCC statistical processing. When “OFF” is set in the flag FLG, the FCC estimation process and the FCC statistical process are not executed. After the flag FLG is set to “ON” by the OCV estimation unit 31, when the FCC estimation process and the FCC statistical process for one time are completed, the OCV estimation unit 31, the FCC estimation unit 35, or the FCC statistical processing unit 36 sets the flag FLG. “OFF” is set.

The FCC estimation process will be described with reference to FIG. Now, the time t _i-1 and t _i between the assumption that the charging or discharging of the battery module 11 is performed in the time t _i-1 and t _i, respectively the estimated SOC by SOC estimating unit 32 in SOC represent at _i-1 and SOC _i. The FCC estimation process is executed every time the flag FLG is set to “ON”. Time t _i-1 corresponds to the execution timing of the (i-1) th FCC estimation process, and time t _i corresponds to the execution timing of the i-th FCC estimation process (i is an integer). The current integration unit 33 can perform the integration process in synchronization with the execution timing of the FCC estimation process. In the example of FIG. 3, the current integration unit 33 sets the period between times t _i−1 and t _i as the target period, and calculates the current integration amount ΣI by integrating the measured current value I during the target period. . A current integrated amount ΣI between times t _i-1 and t _{i is} represented by a symbol ΣI _i . The amount of change in SOC between times t _i-1 and t _i is represented by ΔSOC _i (see the following formula (A1)). Since the SOC represents the remaining capacity of the battery module 11 as a ratio, ΔSOC _i is a type of remaining capacity change.

The estimated value of the full charge capacity FCC by the FCC estimation unit 35 is also referred to as an estimated capacity value for convenience. The FCC estimation unit 35 calculates an estimated capacity value FCC _i that is an estimated value of the full charge capacity FCC at time t _i according to the following formulas (A1) and (A2). After calculating the estimated capacity value FCC _i , the current integration unit 33 resets the current integration amount ΣI, and starts integration of the measured current value I after time t _i starting from a state where ΣI = 0.
ΔSOC _i = SOC _i −SOC _i−1 (A1)
FCC _i = ΣI _i / ΔSOC _i (A2)

The FCC statistical processing unit 36 calculates an output capacity value FCC _OUT that is a detected value of the full charge capacity of the battery module 11 by FCC statistical processing using a plurality of estimated capacity values. FIG. 4 shows a conceptual diagram of generation of the output capacitance value FCC _OUT . In FIG. 4, waveforms 311, 312, 313 and 314 are waveforms of the measured current value I, the estimated SOC value, the FCC estimated value (estimated capacity value FCC _i ), and the FCC output value (output capacity value FCC _OUT ), respectively. Represents. The waveform 313a is obtained by superimposing the waveform 313 on the graph indicating the waveform 314 with a dotted line. In the full charge capacity detection unit 30, instead of output as an output capacitance FCC _OUT estimated capacitance value FCC _i, determines the output capacitance FCC _OUT considering the reliability of each estimated capacitance value FCC _i.

The measured current value I by the current sensor 12 includes errors (such as an offset error and a non-linearity error), and if ΔSOC used for estimating the full charge capacity FCC is small, the ratio of the error of the measured current value I to ΔSOC. As a result, the influence of the error of the measured current value I on the estimated capacitance value FCC _i increases. That is, when ΔSOC used for estimating the full charge capacity FCC is small, the error included in the estimated capacity value FCC _i tends to increase, and the reliability of the estimated capacity value FCC _i is lowered. In the FCC statistical processing, the estimated capacity value corresponding to the relatively low reliability is not reflected in the output capacity value FCC _OUT so much, and the estimated capacity value corresponding to the relatively high reliability is largely reflected in the output capacity value FCC _OUT. As described above, the statistical value of the plurality of estimated capacitance values is obtained as the output capacitance value FCC _OUT . In FIG. 4, for example, the reliability with respect to the estimated capacity value FCC ₂ is set low corresponding to the small ΔSOC ₂ , and as a result, the difference between the estimated capacity value and the output capacity value at time t ₂ is particularly large. .

The details of the FCC statistical processing will be described in detail together with the statistical processing data storage unit 37. FIG. 5 is a partial block diagram of the full charge capacity detection device 30 including an internal block diagram of the FCC statistical processing unit 36. The FCC statistical processing unit 36 includes a reliability deriving unit 51, a statistical calculation unit 52, and an output adjustment unit 53. FIG. 6 shows a correspondence relationship between the remaining capacity change amount ΔSOC _i , the estimated capacity value FCC _i and the reliability W _i that are sequentially obtained, and each time. For any integer i, the time t _{i + 1} is later than time t _i, at time t _i and t _{i + 1,} discharge or charge of the battery module 11, or, as both the charging and discharging is performed To do. ΔSOC _i is a remaining capacity change amount obtained at time t _i (a change amount of SOC between times t _i−1 and t _i ), and FCC _i is an estimated capacity value obtained at time t _i . W _i is the reliability corresponding to the estimated capacity value FCC _i .

The statistical processing data storage unit 37 is formed of a semiconductor memory or the like. Every time the estimated capacity value FCC _i and the reliability W _i are obtained, the statistical processing data together with the time information corresponding to the FCC _i and W _i is obtained. Remember to include. Now, after the time t _n−1 and immediately before the time t _n , the storage unit 37 corresponds to the estimated capacity values FCC _{1 to} FCC _n−1 and the reliability W _{1 to} W _n−1. It is assumed that it is stored in the statistical processing data together with the time information. n is an integer of 3 or more. The time information corresponding to the estimated capacity value FCC _i and the reliability W _i is, for example, the time t _i itself, but may be any information as long as the elapsed time from the time t _i to the current time can be obtained. A set of estimated capacity value, reliability, and time information corresponding to any one time is referred to as set data for convenience.

FIG. 7 is a flowchart showing the operation procedure of the FCC statistical processing. The FCC statistical process includes the processes of steps S11 to S13. Every time the flag FLG is “ON” and the estimated capacity value FCC _i is obtained, the FCC statistical processing including steps S11 to S13 can be performed. Here, _assuming that the time t _n is the current time, the FCC statistical processing at the time t _n will be described.

In step S <b> 11, the FCC statistical processing unit 36 performs statistical data update processing. In the statistical processing data update processing, the FCC statistical processing unit 36 sets, among the statistical processing data stored in the storage unit 37, the set data whose elapsed time exceeds a predetermined data holding time as statistical processing data. Exclude from Here, as shown in FIG. 6, it is assumed that the predetermined data holding time is longer than the time between times t ₂ and t _n but shorter than the time between times t ₁ and t _n . Then, in step S11 executed at time t _n , the set data composed of FCC ₁ , W ₁ and t ₁ is excluded from the statistical processing data stored in the storage unit 37 (in the storage unit 37). Deleted from memory).

In the statistical data update process in step S11, the reliability deriving unit 51 derives a new reliability corresponding to the new estimated capacity value. Here, since at time t _n is estimated capacitance value FCC _n is assumed that newly obtained, a new confidence W _n corresponding to the new estimated capacitance value FCC _n is derived. In the statistical processing data update processing, the set data composed of FCC _n , W _n and t _n is added to the statistical processing data and stored in the storage unit 37. As a result, after completion of the update processing of the statistical processing data at time t _n, the statistical processing data in the storage unit 37 includes FCC _{2 to} FCC _n , W _{2 to} W _n and t _{2 to} t _n. Will be. The reliability deriving unit 51 obtains the reliability W _i so that the reliability W _i increases as the remaining capacity change amount ΔSOC _i increases. Specifically, for example, the reliability W _i is obtained according to the following formula (A3).
W _i = ΔSOC _i (A3)

In step S12 following step S11, the statistical processing unit 52 calculates the statistical capacity value FCC _AVE from the statistical processing data stored in the storage unit 37. At this time, the statistical processing unit 52 has an estimated capacity value corresponding to a relatively large reliability among estimated capacity values FCC _{2 to} FCC _n included in the statistical processing data, and an estimated capacity corresponding to a relatively small reliability. than the value, large as contributing to statistical capacity value FCC _AVE (result, as also greatly contribute to the output capacitance FCC _OUT), obtaining the statistical capacitance value FCC _AVE. Specifically, for example, the statistical processing unit 52 calculates the statistical capacity value FCC _AVE at the time t _n by the weighted average calculation of the estimated capacity values FCC _{2 to} FCC _n using the reliability W _{2 to} W _n as the weighted average coefficient. calculate. That is, the statistical processing unit 52 can calculate the statistical capacity value FCC _AVE at time t _n according to the following formula (A4).

In step S13 following step S12, the output adjustment unit 53 determines the output capacitance value FCC _OUT from the statistical capacitance value FCC _AVE through the output adjustment process. In the output adjustment process, the output adjustment unit 53 can control whether or not the output capacitance value FCC _OUT is updated according to a plurality of reliability levels. That is, for example, in the output adjustment process, the output adjustment unit 53 outputs the statistical capacity value FCC _AVE as it is as the output capacity value FCC _OUT in principle, but the total or average value of the reliability included in the statistical processing data (current value) In the example, when the sum or average value of W _{2 to} W _n is smaller than a predetermined threshold value, the output capacity value FCC _OUT is not updated. If the total or average value of the reliability is low, the reliability of the statistical capacity value FCC _AVE as the estimated value of the full charge capacity is low, and therefore it is possible to output a reasonable capacity value without updating the output capacity value FCC _OUT. It is. More specifically, the output adjustment unit 53 outputs the output capacity value that coincided with FCC _AVE [n−1] when the total or average value of the reliability included in the statistical processing data is equal to or greater than a predetermined threshold. FCC _OUT is updated to FCC _AVE [n] at time t _n , but if the sum or average value is smaller than the threshold value, the output capacity value FCC _OUT is not updated to FCC _AVE [n] at time t _n . Maintain FCC _AVE [n-1]. FCC _AVE [i] represents the statistical capacity value FCC _AVE obtained in step S12 at time t _i .

In the storage battery system 1, for example, a usage pattern in which charging / discharging for so-called peak shift is performed in normal times while ensuring a certain remaining capacity in preparation for a power failure is assumed (see FIG. 12). In such a usage pattern, there is a high possibility that ΔSOC in normal charge / discharge is not sufficiently large. In this embodiment, even in such a usage pattern, by detecting the reliability of FCC estimation from ΔSOC and performing statistical processing according to the reliability, it is possible to detect and output an appropriate FCC or a highly reliable FCC. Is possible. Unlike the second conventional method, even if ΔSOC is small, it is possible to stably obtain FCC _OUT in consideration of reliability (a situation where full charge capacity detection is continuously stopped is avoided).

<< Second Embodiment >>
A second embodiment of the present invention will be described. In the second embodiment and third to seventh embodiments described later, modified techniques of the technique described in the first embodiment will be described. The items described in the second to seventh embodiments can be applied to the first embodiment, and as long as there is no contradiction, the items described in any two or more of the second to seventh embodiments can be freely combined. It can also be applied to the first embodiment.

  The OCV estimation unit 31 may estimate the open-circuit voltage OCV using any known open-circuit voltage estimation method other than the method described in the first embodiment.

Or the OCV estimation part 31 may estimate the open circuit voltage OCV using the method shown below. 8A to 8C and FIG. 9 are referred to. FIG. 8A is an equivalent circuit in the battery module 11. The equivalent circuit in the battery module 11 can be considered to be a series connection circuit of a voltage source VS that outputs the voltage OCV and zero internal resistance, and an impedance circuit Z including a resistance component and a capacitance component. The circuits Z _A and Z _{B in} FIGS. 8B and 8C are a first example and a second example of the internal circuit of the impedance circuit Z. Circuit Z _A includes a resistor R0, a circuit connected in series with the parallel connection circuit of a resistor R1 and a capacitor C1. The circuit Z _B is a circuit in which a resistor R0, a parallel connection circuit of a resistor R1 and a capacitor C1, and a parallel connection circuit of a resistor R2 and a capacitor C2 are connected in series. Hereinafter, the circuit Z _B is regarded as the impedance circuit Z unless otherwise specified.

FIG. 9 shows a waveform 410 _CCV of the measured voltage value CCV and a waveform 410 _OCV of the true open-circuit voltage value of the battery module 11. In FIG. 9, charging and discharging are stopped in a period P0 between times t _A and t _B , and then discharging is performed in a period P1 between times t _B and t _C , and thereafter times t _C and t _D. Charging and discharging are stopped during the period P2. The time t _C0 is the time immediately before the time t _C and belongs to the period P1, and the time t _C1 is the time after the time t _C and belongs to the period P2. The OCV estimation unit 31 firstly calculates the time t t according to the equation (B1) based on the measured values CCV and I at time t _C0 , CCV _ON [t _C0 ] and I [t _C0 ], and the known resistance value R _TOTAL. Estimate the open circuit voltage OCV _{ON: EST} [t _c0 ] of _C0 . The resistance value R _TOTAL conforms to the following formula (B2) (where R0, R1, and R2 indicate the resistance values of the resistors R0, R1, and R2). Thereafter, at time t _C1 , the OCV estimation unit 31 obtains an initial residual voltage V _DIFF according to the following equation (B3) using CCV _OFF [t _C1 ], which is the measured value CCV at time t _C1 . The initial residual voltage V _DIFF is a voltage applied to the circuit Z at time t _C1 (voltage remaining in the circuit Z).

After _{obtaining the} residual voltage V _DIFF , the OCV estimation unit 31 can estimate the open circuit voltage OCV _{OFF: EST} [t] at an arbitrary time t in the period P2 according to the following formula (B4). CCV _OFF [t] is a measured voltage value CCV at time t in the period P2. V _TRANS [t] is a voltage applied to the circuit Z at the time t in the period P2, and when the circuit Z _B is regarded as the circuit Z, it is obtained according to the equation (B5). However, “t” on the right side of the formula (B5) indicates an elapsed time from the time t _C1 . V _DIIF1 and V _DIIF2 are determined according to the following formulas (B6) to (B9) using the initial residual voltage V _DIFF and the known coefficients α ₁ and α ₂ . The time constants τ ₁ and τ ₂ are set in advance through experiments or the like. The values of R _TOTAL , α ₁ , α ₂ , τ _1, and τ ₂ may be fixed values, but may be variable values according to the measurement temperature T or the degree of deterioration of the battery module 11.

Even when charging is performed in the period P1, the open circuit voltage can be estimated by the same method. If this method is used, it is possible to accurately estimate the open-circuit voltage without waiting for the terminal voltage of the battery module 11 to stabilize after stopping charging or discharging. The OCV estimator 31 determines that the open-circuit voltage OCV _{OFF: EST} [t is satisfied when a condition for accurately estimating the open-circuit voltage is established after charging or discharging is stopped (for example, when a predetermined time has elapsed from time t _C ). ] And the flag FLG may be set to “ON”.

<< Third Embodiment >>
A third embodiment of the present invention will be described. Although the reliability of the output capacity value FCC _OUT is ensured by the FCC statistical processing using the reliability W _i , if ΔSOC _i is smaller than a predetermined lower limit value, the estimated capacity value is calculated using ΔSOC _i. The processing for obtaining FCC _i and the FCC statistical processing that should have been performed using FCC _i may not be executed.

<< Fourth Embodiment >>
A fourth embodiment of the present invention will be described. The derivation formula of the reliability W _i is not limited to the above formula (A3). For example, the reliability deriving unit 51, the formula (A3a), according to equation (A3b) or formula (A3c), may be derived reliability W _i.
W _i = (ΔSOC _i ) ² (A3a)
W _i = ΔSOC _i × (d _i-1 + d _i ) (A3b)
W _i = (ΔSOC _i ) ² × (d _i-1 + d _i ) (A3c)

Refer to FIG. 10 for an explanation of d _i−1 and d _i . A curve 440 in FIG. 10 is a curve showing a relationship between the OCV and the SOC with the SOC and OCV taken on the horizontal axis and the vertical axis. FIG. 10 also shows SOC estimated values SOC _i−1 and SOC _{i at} times t _i−1 and t _i by the SOC estimating unit 32. SOC _i-1 and SOC _i are the remaining capacity indexes from which ΔSOC _i used for estimation of FCC _i corresponding to the reliability W _i is calculated (see the above formula (A1)). In equations (A3b) and (A3c), d _i is the slope of curve 440 when SOC = SOC _i−1 , and d _i−1 is the slope of curve 440 when SOC = SOC _i. is there. The reliability deriving unit 51 holds table data or the like that can specify the curve 440, and can use the table data or the like to obtain the gradients d _i-1 and d _i from the SOC _i-1 and SOC _i . The greater the slopes d _i-1 and d _i , the higher the accuracy of SOC estimation, and the higher the reliability of FCC estimation. Therefore, in the formulas (A3b) and (A3c), the reliability W _i is increased as the slopes d _i−1 and d _i increase.

Moreover, FCC statistical processing section 36, after obtaining the reliability W _i at time t _i, may reduce the value of the reliability W _i over time from the time t _i. For example, when the FCC statistical processing unit 36 treats the reliability W _i obtained at time t _i as the initial reliability W _i [INIT] and performs FCC statistical processing at time t _i , the initial reliability W The statistical capacity value FCC _AVE at time t _i is calculated using _i [INIT] as the reliability W _i . Thereafter, when FCC statistical processing is performed at time t _{i + j} , the reliability obtained by subtracting the reliability correction amount from the initial reliability W _i [INIT] is used as the reliability W _i , and time t _{i +} calculating the statistical capacitance value FCC _AVE of _j (where, j is a positive integer, the lower limit of the confidence W _i is zero). The reliability correction amount increases as the time difference between the times t _i and t _{i + j} increases.

<< Fifth Embodiment >>
A fifth embodiment of the present invention will be described. The method of deriving the statistical capacitance FCC _AVE by the formula (A4) are merely exemplary, relatively large corresponding to the reliability is estimated capacitance value is relatively small reliability than the estimated capacitance value corresponding to the statistical capacity value FCC _AVE As long as it greatly contributes to the above, the method for deriving the statistical capacity value FCC _AVE can be variously modified. Alternatively, the statistical calculation unit 52 may obtain the statistical capacity value FCC _AVE from a plurality of estimated capacity values FCC _i without using the reliability. That is, for example, the statistical calculation unit 52 may calculate the statistical capacity value FCC _AVE at time t _n by a simple average of a plurality of estimated capacity values FCC _i according to the following formula (A4a).

<< Sixth Embodiment >>
A sixth embodiment of the present invention will be described. The full charge capacity should basically decrease with deterioration due to use of the battery module 11. Thus, the output adjusting section 53 such that the output capacitance FCC _OUT output does not exceed the initial value of output capacitance FCC _OUT (1 No. initially obtained output capacitance FCC _OUT) at an arbitrary time t _i An upper limit may be imposed on the output capacity value FCC _OUT . That is, for example, when the statistical capacity value FCC _AVE obtained at time t _i is larger than the initial output capacity value FCC _OUT , the output adjustment unit 53 outputs the initial output capacity value FCC _OUT as the output at time t _i . You may output as capacitance value FCC _OUT .

<< Seventh Embodiment >>
A seventh embodiment of the present invention will be described. In the output adjustment process (see FIG. 7) in step S13, the output adjustment unit 53 sets an update restriction range corresponding to a plurality of reliability levels W _i and updates the output capacity value FCC _OUT within the update restriction range. Anyway.

An example of a method for realizing this will be described with reference to FIG. In FIG. 11, each black square represents each statistical capacity value FCC _AVE derived at each time, and each range 530 represents each update limit range set at each time. The statistical capacity value FCC _AVE is obtained according to the method described in the first or fifth embodiment. A solid broken line 510 represents a time change of the output capacitance value FCC _OUT when the output adjustment process including the setting of the update restriction range is performed. When the output adjustment process including setting of the update limit range is performed, the output capacity value FCC _OUT at each time is stored in the update limit range 530 at each time. A broken broken line 520 for reference is obtained when output adjustment processing including setting of the update restriction range is not performed (that is, when the statistical capacity value FCC _AVE derived at each time is directly output as the output capacity value FCC _OUT ). _Represents the time change of the output capacitance value FCC _OUT .

For the sake of concrete description, as in the first embodiment, the time t _n is the current time, a description of the output adjustment processing including setting the update limit range at time t _n. In the output adjustment process at the time t _n , the output adjustment unit 53 first determines the reliability total ΣW _i (in this example, the sum of W _{2 to} W _n ) or the average value included in the statistical processing data, Sets the error width W_ERR. When performing output adjustment processing at time t _n , as described in the first embodiment, since the reliability included in the statistical processing data is the reliability W _{2 to} W _n , the sum ΣW _i is the reliability W _2. which is the total value of ~W _n. For example, the output adjustment unit 53 sets the error width W_ERR according to the following formula (C1). k is a predetermined coefficient. k may be a coefficient proportional to the number of reliability that is the basis of the total sum ΣW _i , that is, (n−1). In this case, the error width W_ERR is an average value of the reliability W _{2 to} W _n (ΣW _i / (n-1)). As long as the error width W_ERR decreases as the reliability sum or average value increases, the calculation formula of the error width W_ERR is not limited to the formula (C1).

The output adjustment unit 53 sets an update limit range having the error width W_ERR based on the statistical capacity value FCC _AVE at time t _n so that fluctuations in the output capacity value FCC _OUT are suppressed as much as possible (that is, output) The output capacitance value FCC _OUT is updated within the update limit range (so that the fluctuation of the capacitance value FCC _OUT is minimized).

In order to clarify and clarify the description, the output capacity value FCC _OUT at times t _n−1 and t _n is represented by symbols FCC _OUT [n−1] and FCC _OUT [n], and the statistical capacity value FCC at time t _{n is shown} . _AVE is represented by the symbol FCC _AVE [n], and the error width W_ERR based on the reliability W _{2 to} W _n is represented by the symbol W_ERR [n]. Then, FCC _OUT [n] is determined through the case division into the following first to third cases. The first to third cases correspond to cases where the time t _n corresponds to the times t _{X1 to} t _X3 in FIG. That is, the output adjustment unit 53
In the first case where the first inequality “FCC _OUT [n−1] ≦ FCC _AVE [n] −W_ERR [n]” is satisfied, the expression “FCC _OUT [n] = FCC _AVE [n] −W_ERR [n]”. To find FCC _OUT [n]
In the second case where the second inequality “FCC _AVE [n] −W_ERR [n] <FCC _OUT [n−1] <FCC _AVE [n] + W_ERR [n]” is satisfied, the expression “FCC _OUT [n] = FCC _OUT [n-1] ”is used to obtain FCC _OUT [n] (ie, FCC _OUT is not updated)
In the third case where the third inequality “FCC _AVE [n] + W_ERR [n] ≦ FCC _OUT [n−1]” is satisfied, the expression “FCC _OUT [n] = FCC _AVE [n] + W_ERR [n]” is satisfied. To obtain FCC _OUT [n].

Since the statistical capacity value FCC _AVE has high reliability when the total or average value of reliability is large, there is little problem in outputting the statistical capacity value FCC _AVE itself or a value close thereto as the output capacity value FCC _OUT. It is reasonable in terms of accuracy. Therefore, in the above method example, the error width W_ERR is reduced when the reliability sum or average value is large. On the other hand, when the total or average value of the reliability is small and the reliability of the statistical capacity value FCC _AVE is low, there is a high possibility that the error of the statistical capacity value FCC _AVE viewed from the true full charge capacity is large. On the other hand, it is often inappropriate or unnatural that the output capacity value FCC _OUT provided to the user or the host system fluctuates greatly. Therefore, when the total or average value of the reliability is small and the reliability of the statistical capacity value FCC _AVE is low, the error width W_ERR corresponding to the width of the update limit range is increased to suppress the fluctuation of the output capacity value FCC _OUT. Prioritize. By such a method, both accuracy guarantee and fluctuation suppression of the FCC output value can be achieved in accordance with the reliability of FCC estimation.

Even in the first or third case, when the reliability sum or average value is smaller than the predetermined threshold, the output capacitance value FCC _OUT is not updated as described in the first embodiment. (That is, FCC _OUT [n] = FCC _OUT [n−1] may be used). Further, the error width W_ERR may be a fixed width that does not depend on the sum of reliability or the average value.

<< Deformation, etc. >>
The embodiment of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims. The above embodiment is merely an example of the embodiment of the present invention, and the meaning of the term of the present invention or each constituent element is not limited to that described in the above embodiment. The specific numerical values shown in the above description are merely examples, and as a matter of course, they can be changed to various numerical values. As annotations applicable to the above-described embodiment, annotation 1 and annotation 2 are described below. The contents described in each comment can be arbitrarily combined as long as there is no contradiction.

[Note 1]
The full charge capacity detection device 30 can be configured by hardware or a combination of hardware and software. Arbitrary specific functions among the functions realized by the apparatus 30 are described as a program, the program is stored in a flash memory that can be mounted on the apparatus 30, and the program is stored in an arithmetic processing unit in the apparatus 30. The specific function may be realized by executing on the microcomputer (for example, a microcomputer that can be mounted on the device 30 or the battery control unit 15).

[Note 2]
For example, it can be considered as follows. The statistical calculation unit 52 and the output adjustment unit 53 form an output processing unit that generates an output capacitance value FCC _OUT based on a plurality of estimated capacitance values FCC _i and a plurality of reliability W _i . It can be said that the output adjustment unit 53 in the seventh embodiment includes an update limit range setting unit that sets an update limit range.

DESCRIPTION OF SYMBOLS 1 Storage battery system 11 Battery module 30 Fully charged capacity detection apparatus 31 OCV estimation part 32 SOC estimation part 33 Current integration part 34 Flag storage part 35 FCC estimation part 36 FCC statistical processing part 37 Statistical processing data storage part 51 Reliability deriving part 52 Statistical calculation unit 53 Output adjustment unit

Claims (7)

Estimated capacity value by estimating the full charge capacity of the battery module based on the remaining capacity change amount during the target period and the integrated amount of current flowing through the battery module during the target period of the battery module comprising the storage battery A full charge capacity estimation unit for generating
A reliability deriving unit for determining the reliability of the estimated capacity value based on the remaining capacity change amount;
An output processing unit configured to generate an output capacity value of the full charge capacity based on a plurality of estimated capacity values generated at a plurality of timings and a plurality of reliability levels corresponding to the plurality of estimated capacity values; A full charge capacity detection device characterized by the above. Increasing the reliability as the reliability deriving unit and the remaining capacity change amount increase,
The output processing unit has an estimated capacity value corresponding to a relatively large reliability among the estimated capacity values generated at the plurality of timings, rather than an estimated capacity value corresponding to a relatively small reliability. The full charge capacity detection apparatus according to claim 1, wherein the full charge capacity detection apparatus greatly contributes to the output capacity value. The output processing unit generates the output capacity value through a weighted average calculation of the plurality of estimated capacity values using the plurality of reliability as a weighted average coefficient. 2. The full charge capacity detection device according to 2. The full-charge capacity detection apparatus according to claim 1, wherein the output processing unit controls whether or not the output capacity value is updated based on the plurality of reliability levels. The output processing unit includes a statistical calculation unit that derives a statistical capacity value based on the plurality of estimated capacity values, and an update limit range setting unit that sets an update limit range according to the plurality of reliability levels, and the update The full charge capacity detection device according to claim 1, wherein the output capacity value is updated within a limited range. The update restriction range has an error width according to the sum or average value of the plurality of reliability levels,
The full charge capacity detection device according to claim 5, wherein the output processing unit updates the output capacity value within the update limit range so that a change in the output capacity value is suppressed. A battery module comprising a storage battery;
A full charge capacity detection device for detecting a full charge capacity of the battery module,
A storage battery system using the full charge capacity detection device according to any one of claims 1 to 6 as the full charge capacity detection device.

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