JP2015165198A - Method and device for estimating state of charge of storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for accurately estimating the state of charge (SOC) of a storage battery.SOLUTION: A device for estimating the state of charge of a storage battery includes: means 104 for calculating the SOC from information on a voltage, charge and discharge currents, and temperature of a storage battery with an arithmetic expression using a coefficient group; means 105 for performing, in creating or updating the coefficient group, switching as to whether make the same or different a direction of charge or discharge during the measurement of a voltage, currents, and temperature of the storage battery for the creation of coefficients and a direction of charge or discharge during the adjustment of the SOC to be a preferred value, which is temporally prior to the measurement; and means 106 for creating/updating the coefficient group for estimating the SOC from the measurements obtained by the above means.

Description

  The present invention relates to a method for detecting (estimating) a state of a storage battery.

  As background art in this technical field, the amount of charge input / output to / from the storage battery is obtained from the current value and its duration, and the remaining amount of the storage battery (hereinafter referred to as SOC: A method (hereinafter referred to as a current integration method) for obtaining State Of Charge) is known. Further, regarding a lead storage battery, Non-Patent Document 1 describes an equation that associates current, voltage, temperature, and SOC at a certain point in time. If the formula described in Non-Patent Document 1 is used, SOC can be obtained from current, voltage, and temperature by convergence calculation.

(The Institute of Electrical Engineers of Japan, B, 128, No. 8, 2008) "Lead-Battery Simulation Modeling Method Using Stepped Current"

  In SOC estimation using the conventional current integration method, errors accumulate as the number of integrations from the reference point increases. In general, a storage battery is designed to satisfy a predetermined performance by operating within an appropriate SOC range. Therefore, if an error is included in the SOC estimation, the operation deviates from the appropriate SOC range, resulting in deterioration of the storage battery. In particular, in storage batteries for wind power and solar power leveling, it is operated for a long time in a partially charged state (hereinafter referred to as PSOC: Partial State Of Charge) so that it can always handle both charging and discharging, Compared to storage batteries for other applications that frequently reach a fully charged state, the problem of cumulative error in SOC using the current integration method was likely to be noticeable.

  Moreover, in the SOC estimation method in which the coefficient is determined using the stepped current pattern described in the conventional (Non-patent Document 1), the estimation error in a specific direction with respect to the exact SOC depending on the type and model of the storage battery. There was a problem that occurred.

  In order to solve the above problems, the storage battery state detection method of the present invention is a procedure for calculating the SOC by an arithmetic expression using a certain coefficient group from information on the voltage, charge / discharge current, and temperature of the storage battery, creating the coefficient group or When updating, the direction of charge or discharge when measuring the voltage, current, and temperature of the storage battery to create the coefficient, and the direction of charge or discharge when adjusting the SOC to a preferred value in time before the measurement And a procedure for switching between the same and different, and a procedure for creating / updating a coefficient group for SOC estimation from the measured values according to the above procedure.

  Since the SOC is calculated from the current values of voltage, current, and temperature, it is possible to avoid the accumulation of errors according to the number of times of accumulation, as in the estimation of SOC using a conventional current integration method. By using a plurality of estimation results in which the direction of error generation with respect to an accurate SOC is reversed, the SOC is estimated from the coefficient created using the step-like current pattern described in the conventional (Non-Patent Document 1). Compared with the method, the error can be reduced. By changing the current direction of charge and discharge that precedes in time, it is possible to create a plurality of SOC estimation coefficients in which the direction of error generation with respect to an accurate SOC is reversed with a sufficiently high probability in practical use.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a figure which shows the whole structure. It is a figure which shows the schematic flow of a SOC calculation part. It is a figure which shows the schematic flow of a SOC coefficient update part. It is a figure which shows the flow of a SOC calculation coefficient update part. It is a figure which shows the flow of SOC adjustment between measurements. It is a figure which shows the flow of a measurement of the electric current for coefficient determination, a voltage, and temperature. It is a figure which shows SOC transition and applied current in the case of sign (Icond) = sign (Imes). It is a figure which shows SOC transition and applied electric current in the case of sign (Icond) <= sign (Imes). It is a figure which shows typically the SOC calculation process which concerns on Example 3 of this invention. It is a figure which shows typically the calculation process by the estimated polarization amount calculation means immediately before. It is a figure explaining the method of adjusting the amount of polarization and making a coefficient by making current application time of Icond variable. It is a figure which shows the electric current application pattern in the case of calculating the SOC estimation coefficient equivalent to the case where the small amount of polarization of a reverse direction is applied immediately after application of the large amount of polarization after Icond application. It is a figure which shows the SOC estimation model with which the polarization by the current fluctuation of a long time constant and the polarization by the current fluctuation of a short time constant are superimposed.

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

  Fig. 1 shows the overall configuration. In this example, a configuration for estimating the SOC of a storage battery used for output fluctuation leveling at a wind power generation site is shown.

  Fig. 101 is a storage battery subject to SOC estimation, 102 is a (bidirectional) converter for charging / discharging the storage battery 101, 103 is a leveling operation that controls the leveling operation and the overall control related to the leveling operation of the site. 104 is a SOC calculation unit (SOC calculation unit) that estimates the SOC of the storage battery 101 based on the measured value, 105 is a charge / discharge of the storage battery 101 according to the control algorithm installed in the leveling control unit 103 based on the SOC estimation result The charge / discharge control unit 106 outputs a charge / discharge command to the converter 102 so as to perform the charge / discharge operation necessary for determining the coefficient when it is necessary to update the coefficient for SOC estimation under a predetermined condition, SOC calculation unit coefficient update unit that determines the coefficient based on the result, 107 is used to realize the charge / discharge operation necessary for determining the SOC estimation coefficient regardless of the input / output of current from the wind power generator or interconnection point Other storage battery banks or charge / discharge devices Ku is the current input and output apparatus capable of such other loads, 108 linking point with an external system, 109 bus, 110 is a wind power generator.

  FIG. 2 shows a schematic flow of tasks executed by the SOC calculation unit 104. The flow shown in FIG. 2 is a task that is started when the time elapsed by the timer or other SOC is required during normal leveling operation, and reads the measured values of voltage, current, and temperature related to the storage battery 101 (s501), Based on the measured value, the SOC is calculated according to a predetermined algorithm (s502), and the calculated SOC is output for subsequent processing (s503).

  The measured values (measurement data) of the voltage, current, and temperature related to the storage battery 101 and other measured values (measurement data) are sent to the leveling control unit 103 as indicated by the one-dot chain line in FIG. Measured at 103. For this purpose, the leveling control unit 103 is provided with a measurement unit that measures various measurement values. The leveling control unit 103 itself may be regarded as constituting a measurement unit for various measurement values.

  A schematic flow of tasks executed by the SOC calculation coefficient update unit 106 is shown in FIG. The flow shown in FIG. 3 is a task that is started when the coefficient for SOC estimation needs to be updated, such as aging. First, the SOC calculation coefficient update necessity determination unit 111 determines whether the estimation accuracy based on the current SOC estimation coefficient is sufficient. For the determination, for example, there is a method of comparing with a current integrated SOC value immediately after equal charge or reset charge. Alternatively, the update may be activated by an external command by SOC calculation coefficient update external input 112. When an update start signal is transmitted from the SOC calculation coefficient update necessity determination unit 111, the SOC calculation coefficient update unit 106 determines whether or not it is possible to shift to the SOC estimation count update mode (s504). When the condition is satisfied, the mode shifts from the generator output fluctuation leveling mode, which is the normal operation mode, to the SOC estimation coefficient update mode (s505). After the transition to the update mode, charge / discharge for calculating the SOC estimation coefficient and measurement are performed (s506). An SOC estimation coefficient is calculated using the measurement result (s507). The calculation result is transferred to the coefficient storage unit used in the SOC calculation unit 104 (s508), and then returned to the generator output fluctuation leveling mode (s509).

  Next, the operation of the charge / discharge and measurement flow (s506) for calculating the SOC estimation coefficient described above will be described with reference to FIG. First, in s511, adjustment is made to a value that becomes a reference point of SOC in a series of measurements for coefficient update. An example of the reference point is SOC 100%. Next, after adjusting the SOC to a predetermined value in s512, the terminal voltage, the storage battery, or the temperature around the storage battery is measured under a predetermined current condition in s513. The SOC adjustment of s512 and the measurement of s513 are generally repeatedly measured over a plurality of SOC states. In s514, it is determined that measurement has been completed over all SOC conditions, and a series of charging / discharging and measurement flows for calculating the SOC estimation coefficient is completed. In this flow, the order of s512 and s513 may be reversed. Further, another s512 may be inserted after s513.

  Next, the operation of the SOC adjustment between measurements in s512 will be described using FIG. First, at s521, the SOC target value is set. For example, when the current value of SOC is 100%, if the measurement of s513 is to be performed at SOC 90%, the SOC achievement target is SOC 90%. At this time, the reaching target may be based on the SOC variation ΔSOC instead of the SOC absolute value. For example, the value of ΔSOC is 3% or more and less than 40%. The lower limit of ΔSOC is set to an amount sufficient to cause a terminal voltage deviation from the OCV (Open Circuit Voltage) state due to charge / discharge. Therefore, a small ΔSOC can be used in a storage battery that is prone to polarization. The opposite is true for storage batteries that are less prone to polarization. On the other hand, if ΔSOC is excessively large, the resolution of the SOC estimation coefficient with respect to SOC decreases. For example, in a measurement with a DOD (Depth of Discharge) of 80%, if ΔSOC is 40%, the number of sampling points for the SOC is 3.

  Note that, in the SOC adjustment in this series of measurements, since the integration time (number of integrations) from the SOC reference point is small, it is assumed that the current integration SOC is used, but this is not restrictive. After setting the target SOC, a current Icond (abbreviation for I conditioning) is applied for SOC adjustment in s522. Current application to the target storage battery 101 depends on the exchange of current with other storage battery banks and other current input / output devices 107 that have multiple banks, adjustment of current distribution, and contract conditions, but external AC This is done either by exchanging current with the power supply. The value of Icond is naturally within the limit value of the charge / discharge current of the target storage battery, but it is less than the maximum value of the applied current Imes (abbreviation of I measurement) at the time of measurement for determining the coefficient at the subsequent stage. Use the value above as a guide. An example is 0.1 CA (1 CA is a current value at which a fully charged storage battery can be completely discharged in one hour, provided that the capacity does not depend on the discharge current value). The current value directly affects the time required for the measurement for calculating the SOC estimation coefficient, and also affects the characteristics of the derived SOC estimation coefficient. For example, when the value of Icond is increased, the amount of change in the terminal voltage is increased after the SOC adjustment with the same current as compared with the OCV state. This seems to be the effect of polarization and the like. When the Icond is high, the better SOC estimation coefficient can be obtained according to the characteristics of the wind site to be leveled (wind conditions, generator characteristics, etc.). Hereinafter, as a definition of the current direction, a negative value is a charging direction and a positive value is a discharging direction. Therefore, sign (Icond) = − 1 for Icond in the charging direction, and sign (Icond) = 1 for Icond in the discharging direction. Sign (·) is an operator that converts the sign in parentheses into a value obtained by adding the same sign to absolute value 1.

  In s523, after determining that the SOC calculated based on the integrated value of Icond * Tcond has reached the target value, the SOC adjustment is terminated. If the target value has already been reached in step s521, the process ends without being shown in the figure.

Next, the coefficient determination current, voltage, and temperature measurement operations in s513 will be described with reference to FIG. First, in s531, the application direction (charging direction or discharging direction) of the measurement current Imes applied in the next stage is determined. In s532, Imes in the direction determined in the previous step is applied. With application of Imes, terminal voltage, current, and storage battery temperature (or temperature around the storage battery) are measured in s533.
As Imes is applied, the terminal voltage of the storage battery changes almost asymptotically to a constant value (provided that the current value before Imes application (= Icond) and the current value of Imes are different). The measurement is terminated when the change amount becomes sufficiently small, when the ΔSOC conversion amount exceeds a certain value, or when a predetermined time Tmes elapses (s534). The above steps are sequentially applied with respect to a plurality of Imes, and are completed with the application with respect to all the Imes (s535). As for the value of Imes, for example, a value smaller than Icond, a value about Icond, and a value more than Icond are selected about three or more points. Further, in the loop including s532, if Imes is applied in the order of the value having the smallest absolute value to the value having the largest absolute value, the influence of the terminal voltage fluctuation due to the application of the immediately preceding Imes can be reduced.

  Next, a configuration example of the SOC estimation coefficient in s507 of FIG. 3 is shown.

  When SOC is S [dimensionless, full charge: 1, complete discharge: 0], battery voltage is v [V], and battery current is i [A], the relationship between SOC and battery voltage v is (Equation 1) Indicated by

Here, the coefficients Cv1, Cv2, and Cv3 in (Expression 1) are expressed by the following (Expression 2) in relation to the current value i during charging.

(Equation 1) is a form to calculate voltage from SOC, current, temperature (reflected in coefficient value) for convenience, but using a widely known quadratic equation solution formula, S is positively calculated. Can be easily converted. You may use the method of calculating | requiring S numerically with the iterative method using a golden section etc.

Here, regarding the coefficient group Cxx in (Expression 1) and the coefficient group Cyyyy in (Expression 2),
A coefficient group derived from measurement data under the condition of sign (Icond) = sign (Imes) and sign (Imes) = − 1 is a forward charge coefficient (hereinafter Ccf),
-The coefficient group derived from the measurement data under the condition of sign (Icond) = sign (Imes) and sign (Imes) = 1, the forward discharge coefficient (hereinafter Cdf),
-The coefficient group derived from the measurement data under the condition of sign (Icond) ≠ sign (Imes) and sign (Imes) = -1, the charging coefficient in the reverse direction (hereinafter Ccr),
-The coefficient group derived from the measurement data under the condition of sign (Icond) ≠ sign (Imes) and sign (Imes) = 1, the discharge coefficient in the reverse direction (hereinafter Cdr),
It is defined as

  In addition, using Ccf, the calculated SOC value is expressed as S (Ccf) (the same applies to other coefficient groups).

  Here, FIG. 7 shows an example of SOC transition and applied current when sign (Icond) = sign (Imes), and FIG. 8 shows an example of SOC transition and applied current when sign (Icond) ≠ sign (Imes). As shown, any method may be used as long as the current application for applying the terminal voltage variation from the OCV is performed prior to the measurement for determining the coefficient, and is not limited to the illustration.

Next, when actually performing SOC estimation using the SOC estimation coefficient, not in the stage of creating the SOC estimation coefficient, it is convenient to determine which coefficient is applied to the charge / discharge direction and calculated. The following formula is used.
Sl = Sc (Ccf) + Sd (Cdr) (Formula 3)
The first term on the right side of the above (Equation 3) applies the coefficient group Ccf in the SOC estimation (Sc) when the current in the charging direction is applied to the storage battery subject to the SOC estimation, The term is a pseudo representation of calculating the SOC by applying the coefficient group Cdr in the SOC estimation (Sd) of the discharge direction. The left side Sl of the above (Equation 3) indicates that the calculation result is an estimation result that is predicted in advance to be a lower (SOC Low) SOC estimation value.

Similarly, a convenient expression that is expected to be a higher (SOC High) SOC estimation result is the following (formula 4).
Sh = Sc (Ccr) + Sd (Cdf) (Formula 4)
Using the results of (Equation 3) and (Equation 4) described above, the SOC estimation result Sout of this example is expressed by the following (Equation 5).
Sout = p * Sl + (1-p) * Sh (Formula 5)
Here, p is a coefficient that divides Sl and Sh inward and outward, and using 0.5, for example, indicates that the midpoint of both is the SOC estimation result. The above p is appropriately adjusted according to the characteristics of the wind power site actually applied in addition to the characteristics of the storage battery.

  The SOC estimation coefficient creation method and the SOC estimation method shown in the above embodiment may be applied not only when the SOC estimation coefficient is updated, but also when it is performed only once when the leveling storage battery system is manufactured. Alternatively, the present invention may be applied to a case where a new storage battery of a new type or revision is introduced only once.

  Next, a second embodiment will be described.

Depending on the characteristics of the storage battery, at least one of the charging direction and the discharging direction may be smaller than the terminal voltage fluctuation due to the immediately preceding current state. In that case, it is a combination of the previous (formula 3) (formula 4),
Sl = Sc (Ccf) + Sd (Cdr), Sh = Sc (Ccr) + Sd (Cdf)
Instead of, the following combinations can be used.

When the terminal voltage fluctuation in the discharge direction is small, the following (Equation 6) or (Equation 7) is used.
Sl = Sc (Ccf) + Sd (Cdf), Sh = Sc (Ccr) + Sd (Cdf) (Formula 6)
Sl = Sc (Ccf) + Sd (Cdr), Sh = Sc (Ccr) + Sd (Cdr) (Formula 7)
When the terminal voltage fluctuation in the charging direction is small, the following (Equation 8) or (Equation 9) is used.
Sl = Sc (Ccf) + Sd (Cdr), Sh = Sc (Ccf) + Sd (Cdf) (Formula 8)
Sl = Sc (Ccr) + Sd (Cdr), Sh = Sc (Ccr) + Sd (Cdf) (Formula 9)
Using any of (Equation 6) to (Equation 9) above can reduce the number of measurements to determine the coefficient group for SOC estimation, thus reducing man-hours and reducing the impact on wind turbine operating time . Or if it is the same operation time, the update frequency of a coefficient can be increased.

  Next, a third embodiment will be described.

  The inner / outer division coefficient p in (Equation 5) in the first example was a fixed value. Here, p is a variable value. As a variable method of p, there is a method of using an amount based on a moving average or temporary delay value of a current value in a certain period, which is preceded in time, and appropriately multiplying by a coefficient of magnification and an offset, and good correction can be performed.

p = (temporary current delay value-offset) * magnification factor (Equation 10)
The variable of p is particularly effective when applied to a form in which an error in SOC estimation tends to remain due to asymmetry, as in (Expression 6) to (Expression 9). FIG. 9 schematically shows these processes. In the figure, the immediately preceding estimated polarization amount calculation unit calculates the above-mentioned p. The SOC is calculated from the calculation result of Sh and Sl and the degree of tilt using p. In the schematic circuit of FIG. 9, only the inner part is shown, but it can be extended to the outer part as it is.

  In the previous embodiment, the assumption was made that the positions of the inner and outer portions of Sh and Sl are linearly proportional to the amount of polarization. Depending on the type of storage battery and the charge / discharge pattern, the above relationship may be nonlinear. In this case, the calculation using a plurality of coefficient groups of S_1, S_2,. good. The coefficient is created by adjusting the amount of polarization by changing the current application time of Icond as indicated by t1 and t2 in FIG. At the time of SOC estimation, the most similar condition to the polarization amount for determining the coefficient is calculated by the estimated polarization amount calculating means immediately before FIG. 10, and the weight Wm corresponding to the most similar coefficient is weighted. As a simple example, the weight Wm = 1 corresponding to the most similar coefficient group is set, and the other weights are set to 0. Alternatively, the weights normalized so that the sum is 1 may be distributed according to the degree of similarity. When creating multiple coefficient groups S_1, S_2, ..., S_n, the amount of polarization (corresponding to the current application time of Icond) is adjusted by the characteristics of the wind at the wind site that actually performs the SOC estimation (wind conditions) ) May be adjusted as appropriate. This is because fluctuations in the amount of power generated by wind power generation are limited in describing with a one-dimensional value of the amount of polarization. On the other hand, when the number of dimensions is increased, it is not always possible to expect an improvement in accuracy commensurate with an increase in maintenance man-hours such as coefficient updating. On the contrary, the work which maintains many coefficients appropriately under the situation where many factors including the deterioration of the storage battery are acting is not feasible. Therefore, a method of projecting to a one-dimensional weighting by analyzing the actual value of the actual generated power pattern of the target wind site and adjusting the amount of polarization (corresponding to the current application time of Icond) is practical. I think it is useful.

  FIG. 12A and FIG. 12B are examples of current application patterns for calculating an SOC estimation coefficient corresponding to a case where a small amount of polarization in the reverse direction is applied immediately after application of a large amount of polarization after Icond application. The same current application pattern may be obtained by making the application time of Icond extremely small, but it is not efficient and there is a possibility that an estimation coefficient reflecting another characteristic may be formed. Therefore, by using the application pattern shown in FIG. The coefficient is obtained when is applied. Although not shown, there are four combinations for obtaining these coefficients depending on the current direction of Icond and the context of ImesCn and ImesDn. As shown in this example, a case where the current in the direction of charging or discharging continues and then becomes a current in the reverse direction for a short time and then becomes the current in the original direction again is often the case in storage batteries for wind power output fluctuation suppression applications. It is a charge / discharge pattern that can be seen. For example, after a discharge lasts for a long time, charging with large amplitude occurs for a short time when the wind speed gradually increases, reaches the wind speed at which the windmill should be cut off for a short time, and then weakens to the wind speed at which power can be generated again. It is. For a similar purpose, as shown in FIG. 12B, the SOC estimation coefficient may be created with a pattern including inversion of the current direction for a shorter period.

  Using the current pattern shown in FIG. 12B, an SOC estimation coefficient that takes into account the influence of polarization on current fluctuation in a very short time is created. In this case, the SOC estimation model shown in FIG. 13 in which polarization due to current fluctuation with a longer time constant and polarization due to current fluctuation with a short time constant are superimposed may be applied. This provides an effect similar to that in which two parallel circuits of CR (capacitor and resistor) that are generally used are configured in series when describing the characteristics of the storage battery with an equivalent circuit. In other words, the effect of polarization due to a change in current with a relatively large time constant (weighted WL) and the effect of polarization due to a change in current with a relatively small time constant (weighted Ws) are superimposed. Thus, a more accurate SOC estimation value can be obtained. Similarly, not only two series but also respective coefficients may be obtained with time constants corresponding to a multistage configuration of three or more series, and the SOC may be estimated by weighting similarly. The calculation of the weight can be easily obtained by numerically calculating a known low-pass filter having a different cutoff frequency or a first-order lag value having a different time constant.

  In addition, this invention is not limited to each above-mentioned Example, Various modifications are included. For example, the above-described embodiments are for explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units (calculation units), processing means, and the like may be realized in hardware by designing a part or all of them, for example, with an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function can be stored in a memory, a hard disk, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

  101 ... Storage battery, 102 ... Converter, 103 ... Leveling control unit, 104 ... SOC calculation unit, 105 ... Charge / discharge control unit, 106 ... SOC calculation coefficient update unit, 107 ... Other current input / output devices, 108 ... External system 109 ... busbar, 110 ... wind power generator, 111 ... SOC calculation coefficient update necessity determination unit, 112 ... SOC calculation coefficient update external input, s501 to s535 ... steps of the flowchart.

Claims (5)

In the method for estimating the state of charge of a storage battery,
The procedure for calculating the state of charge by an arithmetic expression using a certain coefficient group from information on the voltage, charge / discharge current, and temperature of the storage battery, and the voltage and current of the storage battery for creating the coefficient group when creating or updating the coefficient group The direction of charging or discharging at the time of temperature measurement and the direction of charging or discharging at the time prior to the measurement and adjusting the charging state to a preferred value are switched between the same or different. A method for estimating a state of charge of a storage battery, comprising: a procedure; and a step of creating / updating a coefficient group for estimating a state of charge from a measurement value obtained by applying the procedure. The method for estimating the state of charge of a storage battery according to claim 1,
Using both the calculation result by the coefficient group created by making the two current directions the same for the storage battery at the time of charging and the calculation result by the coefficient group created by making the two current directions different by the battery at the time of the discharge The first state of charge value calculated by
Using both the calculation result by the coefficient group created with the two current directions different for the storage battery during charging and the calculation result by the coefficient group created by making the two current directions the same for the storage battery during discharge The second state of charge value calculated by
A method for estimating the state of charge of a storage battery, wherein the state of charge is estimated using a battery. The method for estimating the state of charge of a storage battery according to claim 1,
Using both the calculation result by the coefficient group created by making the two current directions the same for the storage battery at the time of charging and the calculation result by the coefficient group created by making the two current directions different by the battery at the time of the discharge The first state of charge value calculated by
Using both the calculation result by the coefficient group created by making the two current directions the same with respect to the storage battery at the time of charging and the calculation result by the coefficient group created by making the two current directions the same with respect to the storage battery at the time of discharge The calculated third charge state value,
A method for estimating the state of charge of a storage battery, wherein the state of charge is estimated using a battery. The method for estimating the state of charge of a storage battery according to claim 1,
Using both the calculation result of the coefficient group created with the same direction of the two currents for the storage battery during charging and the calculation result of the coefficient group created with the same direction of the two currents for the storage battery during discharge And the third state of charge value calculated by
Using both the calculation result by the coefficient group created with the two current directions different for the storage battery during charging and the calculation result by the coefficient group created by making the two current directions the same for the storage battery during discharge The second state of charge value calculated by
A method for estimating the state of charge of a storage battery, wherein the state of charge is estimated using a battery. In the storage battery charge state estimation device,
Storage battery current, voltage, temperature measurement unit, determination unit for determining whether or not the coefficient group needs to be updated when a predetermined condition is satisfied, and a coefficient for controlling measurement for updating the coefficient group according to an instruction from the determination unit An update unit, a control unit that switches the charge / discharge direction so as to obtain a terminal voltage that is higher or lower than the open-circuit voltage in time before acquisition of a measurement value used for coefficient calculation in the coefficient update unit, and the control unit A calculation unit that calculates a plurality of charge states from a plurality of coefficient groups created under different conditions of the switching direction and calculates the estimated values of the plurality of charge states, and calculates a new charge state estimate. An apparatus for estimating the state of charge of a storage battery.

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