JP2014059206A - Charge state estimation device and charge state estimation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge state estimation device and a charge state estimation method for a secondary battery which estimate an SOC value more accurately for variations in SOC-OCV characteristics due to charging and discharging and reduce an estimation error of the SOC.SOLUTION: The charge state estimation device comprises: a plurality of SOC-OCV characteristics tables 4-1 each containing a full charge characteristic curve, a complete discharge characteristic curve, and at least one SOC-OCV characteristic curve dividing a region between the full charge characteristic curve and the complete discharge characteristic curve, each of the SOC-OCV characteristic curves being given a travel value; a travel amount calculation part 4-2 calculating, based on a current integration amount by charging and discharging and a travel value of the SOC-OCV characteristic curve used immediately before the charging and discharging, a travel amount of the SOC-OCV characteristic curve according to the current integration amount; an SOC-OCV characteristics selection part 4-3 determining a travel value closest to the travel amount and selecting an SOC-OCV characteristic curve of the travel value; and an SOC estimation part 4-5 estimating an SOC value from a measured OCV value by using the selected SOC-OCV characteristic curve.

Description

  The present invention relates to a state-of-charge estimation apparatus and a state-of-charge estimation method for a secondary battery, and in particular, a state of charge (SOC) is determined from an open circuit voltage (OCV) of the secondary battery and an SOC-OCV characteristic. The present invention relates to a state-of-charge estimation device and a state-of-charge estimation method that reduce the estimation error when estimating based on the method.

  In devices such as automobiles and electrical equipment that use secondary batteries such as lithium-ion batteries, the performance is greatly affected by the performance of the secondary battery used. It is required to control well and maintain high performance of the secondary battery.

  In such a secondary battery, the state of charge (hereinafter referred to as “SOC”) is based on the SOC-OCV characteristic indicating the correlation between SOC and OCV from the open circuit voltage (hereinafter referred to as “OCV”) of the secondary battery. 5A shows an example of the SOC-OCV characteristic.

  The SOC-OCV characteristic has a characteristic that the characteristic curve varies between charging and discharging due to the influence of the internal resistance and polarization phenomenon of the secondary battery. FIG. 5B shows an example of variation in SOC-OCV characteristics. In FIG. 5B, 5-1 indicates the SOC-OCV characteristic (hereinafter referred to as “full charge characteristic”) when the battery is charged from the fully discharged state to the fully charged state. Reference numeral 5-2 represents SOC-OCV characteristics (hereinafter referred to as “complete discharge characteristics”) when discharged from a fully charged state to a fully discharged state.

  When the secondary battery is charged or discharged in a state between full discharge and full charge, the characteristic curve to follow as the SOC-OCV characteristic depends on the past charge / discharge implementation state. However, it is difficult to specify exactly what characteristic curve the SOC-OCV characteristic becomes for each charge / discharge.

  Therefore, in general, the SOC is estimated using an average characteristic 5-3 that is an average value between the full charge characteristic 5-1 and the complete discharge characteristic 5-2 as the SOC-OCV characteristic. FIG. 5A shows an example of the average characteristic 5-3 of the SOC-OCV characteristic.

  Although it is difficult to accurately determine what kind of characteristic curve the SOC-OCV characteristic will be when charging / discharging is performed, during charging / discharging in a normal charging state between the fully discharged state and the fully charged state As shown in FIG. 6A, the SOC-OCV characteristic follows between the full charge characteristic 5-1 and the complete discharge characteristic 5-2.

  When the charging / discharging is repeated, the OCV varies between the full charge characteristic 5-1 and the complete discharge characteristic 5-2 as shown in FIG. In the SOC-OCV characteristic, the slope is not uniform, and the slope of the characteristic curve is steep in the vicinity of the fully charged state (SOC = 100%) or the fully discharged state (SOC = 0%). In the middle normal charging state area, the slope of the characteristic curve is gentle.

  For this reason, even if the integrated amount of charge / discharge current is the same, the amount of fluctuation in the OCV value varies depending on the state of charge (SOC) and depending on whether the charge or discharge is performed. It is difficult to determine the fluctuation amount of the OCV value.

  As described above, prior art for performing battery control with high accuracy for a secondary battery (large hysteresis battery) in which the relationship between the OCV and the SOC changes depending on the charge / discharge history is, for example, Patent Documents 1 to 3 listed below. Is known by.

  The technique described in Patent Document 1 relates to a method of charging to near the maximum normal voltage value and then discharging to the vicinity of the target voltage value when the reference state battery voltage drops below the normal minimum voltage value. .

  The technique described in Patent Document 2 pays attention to the hysteresis characteristic generated by charging / discharging of the secondary battery, and calculates the current SOC value obtained based on integration of the charging / discharging amount of the secondary battery and a predetermined target SOC value. This relates to charge / discharge control for converging the difference.

  The technique described in Patent Document 3 and the like shows a SOC-OCV characteristic by separately measuring the OCV after charging and the OCV after discharging for a secondary battery in which the OCV after charging is different from the OCV after discharging. The present invention relates to a technique for calculating a charging rate with high accuracy by selectively applying a charging side table and a discharging side table as a charging rate calculation table.

JP 2000-261905 A JP 2002-238106 A JP2011-169817A

  In general, when estimating the SOC value from the measured OCV value, the average characteristic of the SOC-OCV characteristic as shown in FIG. 5A is used. The SOC estimated using this average characteristic is used. The value of is actually estimated including an error due to fluctuations in the SOC-OCV characteristics due to the above-described charge / discharge history.

  That is, as shown in FIG. 5B, when the average characteristic 5-3 of the SOC-OCV characteristic is used for the measured OCV value Vp, the estimated value of SOC becomes Sp. The possible value of the SOC is any value between the SOC value S1 in the full charge characteristic 5-1 and the SOC value S2 in the complete discharge characteristic 5-2. The estimated value Sp of the SOC is a maximum. It includes an error of E1 or E2 which is the difference between them.

  Therefore, when the SOC value is calculated from the measured OCV value based on the average characteristic 5-3 of the SOC-OCV characteristic, the SOC value is not a true value in most cases. However, it is extremely difficult to specify exactly which value the SOC value is true for fluctuations in the SOC-OCV characteristics, and it is virtually impossible.

As an effect of not specifying the true value of SOC,
(1) The charge / discharge control of the secondary battery cannot be performed properly, and the safety in use of the secondary battery is reduced.
(2) The range of usable electrical energy is underestimated due to the SOC estimation error.
(3) In determination in power control and the like, accuracy of determination using the SOC value is impaired, and power control and the like can be performed appropriately.
Problems arise.

  In view of the above problems, the present invention estimates the SOC-OCV characteristic closer to the true value in accordance with the state of charge / discharge with respect to fluctuations in the SOC-OCV characteristic due to charge / discharge, and the estimated SOC-OCV A state of charge estimation device and a state of charge estimation method capable of estimating an SOC value using characteristics and reducing an SOC estimation error are provided.

  A state-of-charge estimation device according to one aspect of the present invention is a state-of-charge estimation device that estimates SOC based on SOC-OCV characteristics from OCV, and is a full charge characteristic, a complete discharge characteristic, the full charge characteristic, and a full discharge. SOC-OCV characteristic table in which a plurality of SOC-OCV characteristics including at least one SOC-OCV characteristic that divides the area between the characteristics are mapped, and a movement value is assigned to each SOC-OCV characteristic The amount of movement for calculating the amount of movement of the SOC-OCV characteristic according to the amount of integrated current based on the current accumulated amount due to charging / discharging and the movement value of the SOC-OCV characteristic used immediately before the charging / discharging A calculating unit and a movement value closest to the movement amount calculated by the movement amount calculating unit are determined, and an SOC-OCV characteristic of the movement value is selected from the plurality of SOC-OCV characteristics. C-OCV characteristic selection means, and SOC estimation means for estimating the SOC value from the measured OCV value using the SOC-OCV characteristic selected by the SOC-OCV characteristic selection means. is there.

  As a result, the movement amount of the SOC-OCV characteristic that fluctuates according to the current integrated amount of the charge / discharge current is estimated, and the SOC-OCV characteristic that is closest to the movement amount is obtained from a plurality of SOC-OCV characteristics prepared in advance. It is possible to reduce the SOC estimation error by selecting and estimating the SOC using the SOC-OCV characteristic.

  Further, the movement amount calculation means performs an operation for moving the movement amount of the SOC-OCV characteristic downward with respect to the current integration due to discharging as compared with the current integration due to charging. As a result, the movement amount is corrected downward with respect to the current integrated amount at the time of discharge as compared with the time of charge, and the SOC-OCV characteristic can be selected with higher accuracy.

  In addition, there is provided SOC-OCV characteristic deterioration estimation means for generating an SOC-OCV characteristic obtained by multiplying the SOC-OCV characteristic selected by the SOC-OCV characteristic selection means by a deterioration coefficient corresponding to the deterioration year of the secondary battery. The SOC estimation means estimates the SOC value using the SOC-OCV characteristic generated by the SOC-OCV characteristic deterioration estimation means. Thereby, it is possible to estimate a highly accurate SOC value according to the aging of the secondary battery.

  According to the present invention, the SOC-OCV characteristic that is closer to the true value is estimated in accordance with the state of charge / discharge with respect to the fluctuation of the SOC-OCV characteristic due to the charge / discharge, and the estimated SOC-OCV characteristic is used. Thus, the estimation error of the SOC can be reduced by estimating the SOC value.

It is a figure which shows the example of the curve of the added SOC-OCV characteristic by this invention. It is a figure which shows the example of the flow of selection of a SOC-OCV characteristic. It is a figure which shows the example of the flow of selection of a deterioration map. It is a figure which shows the structural example of the functional block of the charge condition estimation apparatus of this invention. It is a figure which shows an example of a SOC-OCV characteristic. It is a figure which shows an example of the SOC-OCV characteristic at the time of charging / discharging.

  Embodiments of the present invention will be described in detail based on the following examples. In the present invention, as shown in FIG. 1, the SOC-OCV characteristic (full charge characteristic) 5-1 curve when charged from the fully discharged state to the fully charged state, and when discharged from the fully charged state to the fully discharged state SOC-OCV characteristic 1 that passes through points of different SOC values for each OCV value in the SOC-OCV characteristic region surrounded by the curve of SOC-OCV characteristic (complete discharge characteristic) 5-2 -1,1-2,1-3 are newly added.

  The newly added SOC-OCV characteristics 1-1, 1-2, and 1-3 include 0% and 100% OCV voltages of 3.0 V and 4 in the full charge characteristics 5-1 and the full discharge characteristics 5-2. .1V passes through the point, but does not intersect at other points, and is added to divide the SOC-OCV characteristic region surrounded by the full charge characteristic 5-1 and complete discharge characteristic 5-2 almost evenly. To do.

  The SOC-OCV characteristic table that maps and stores the correspondence relationship between the SOC and the OCV includes a full charge characteristic 5-1, a complete discharge characteristic 5-2, and newly added SOC-OCV characteristics 1-1, 1-2, and the like. The correspondence relationship between each SOC 1-3 and OCV 1-3 is mapped and stored.

  As the newly added SOC-OCV characteristics 1-1, 1-2, and 1-3, FIG. 1 shows an example in which three are added. However, the number of added SOC-OCV characteristics 1-1, 1-2, and 1-3 is not limited to three. It can be appropriately increased or decreased depending on the characteristics of the battery and the required SOC estimation accuracy, and by adding at least one, the accuracy of the SOC can be improved as compared with the conventional case. Hereinafter, an embodiment in which three are added will be described.

  The SOC is estimated by adding five SOC-OCV characteristics including three newly added SOC-OCV characteristics 1-1, 1-2, and 1-3, a full charge characteristic 5-1 and a complete discharge characteristic 5-2. Use any of the characteristics. Here, the SOC-OCV characteristic 1-2 is an average characteristic of the full charge characteristic 5-1 and the complete discharge characteristic 5-2, and the SOC-OCV characteristic 1-1 is the full charge characteristic 5-1 and the average characteristic 1. -2 and the SOC-OCV characteristic 1-3 is an average characteristic of the complete discharge characteristic 5-2 and the average characteristic 1-2.

  Table 1 shows an example of an SOC-OCV characteristic table in which each SOC value corresponding to each OCV value is mapped for each of the five SOC-OCV characteristics.

ＳＯＣ−ＯＣＶ特性テーブルは、各ＳＯＣ−ＯＣＶ特性のそれぞれに対応付けて付与した移動値を同時に保持する。表１に示す例では、平均特性１−２の位置を基準位置として平均特性１−２の移動値を０とし、この平均特性１−２からの移動量（乖離）を示す移動値を、他のＳＯＣ−ＯＣＶ特性に対して付与している。

The SOC-OCV characteristic table simultaneously holds movement values assigned in association with the respective SOC-OCV characteristics. In the example shown in Table 1, the position of the average characteristic 1-2 is set as a reference position, the movement value of the average characteristic 1-2 is set to 0, and the movement value indicating the movement amount (deviation) from the average characteristic 1-2 is set to other values. To the SOC-OCV characteristics.

  Therefore, the movement value of the full charge characteristic 5-1 is 1, the movement value of the complete discharge characteristic 5-2 is -1, the average characteristic SOC-OVC characteristic 1-1 of the full charge characteristic 5-1 and the average characteristic 1-2. Is 0.5, and the movement value of the average characteristic SOC-OVC characteristic 1-3 of the complete discharge characteristic 5-2 and the average characteristic 1-2 is -0.5.

  With respect to these five SOC-OCV characteristics, how the OCV value moves in the SOC-OCV characteristic area by integrating the currents input to and output from the secondary battery by charging and discharging, and is used for estimating the SOC. It is estimated how the SOC-OCV characteristic moves. Then, the estimation error of the SOC is reduced by estimating the SOC using the SOC-OCV characteristic of the estimated movement value.

  When charging from the point P2 on the complete discharge characteristic 5-2 to the point P1 on the full charge characteristic 5-1, in the central area of the normal use state in the SOC-OCV characteristic, the charge characteristic 1-4 of FIG. It is assumed that when the discharge is made from the point P1 on the full charge characteristic 5-1 to the point P2 on the complete discharge characteristic 5-2, the curve becomes the curve of the discharge characteristic 1-5 in FIG. It is difficult to specify accurately.

  Therefore, the SOC change amount ΔSOC from the point P2 to the point P1 where the movement value of the SOC-OCV characteristic changes from the minimum value (= −1) to the maximum value (= + 1) is measured in advance, and the SOC with respect to the change amount ΔSOC is measured. The ratio of the maximum change width (= 2) of the movement value of the -OCV characteristic is calculated as the movement coefficient. When discharging, the change amount of OCV becomes larger than the same change amount ΔSOC as compared with the time of charging. Therefore, when discharging, the movement coefficient is multiplied by a downward correction coefficient for correcting the movement value downward. .

The amount of change ΔSOC in the SOC that varies depending on the amount of accumulated current input to and output from the secondary battery due to charge / discharge is
ΔSOC = accumulated current ÷ full capacity (Equation 1)
Is calculated by

Therefore, the amount of movement of the SOC-OCV characteristic that varies due to the integration of current input to and output from the secondary battery is calculated by the following equation.
Movement amount = previous movement value−ΔSOC × movement coefficient × downward correction coefficient (Equation 2)
With respect to the movement amount calculated by the above (Expression 2), it is determined which movement value is the closest to the movement amount among the movement values that are discrete values, and the closest movement value is selected.

  In (Expression 2), the initial value of the previous movement value is 1 when charging from the fully discharged state. (In the fully charged state, since the value is close to the full charge characteristic 5-1, it is set to 1 which is the movement value of the full charge characteristic 5-1.) Further, the integrated current in the calculation of ΔSOC is the discharge The current is positive and the charging current is negative. As described below, the movement coefficient is 1 / 8.1 as an example. Further, the downward correction coefficient is 1 at the time of charging, and is determined depending on the characteristics of the secondary battery at the time of discharging.

  Here, the movement coefficient will be described in detail. As for the SOC-OCV characteristic, the difference between the SOC and the OCV varies depending on the area between the charge characteristic and the discharge characteristic. In this embodiment, since the SOC value is estimated from the OCV value, the complete discharge characteristic 5 is obtained in an area (area L shown as an example in FIG. 1) in which the deviation of the SOC value is the largest with respect to the same OCV value. The accumulated current amount at which the OCV fluctuates from the point -2 to the point of the full charge characteristic 5-1.

  An SOC change amount ΔSOC corresponding to the integrated current amount is calculated, and 16.2% is obtained as an example. That is, if the SOC is changed by charging 16.2%, the full discharge characteristic 5-2 shifts to the full charge characteristic 5-1. Since -1 changes to +1 and the change width is 2, 2 / 16.2 = 1 / 8.1 is determined as the movement coefficient. The movement coefficient is a coefficient that normalizes the movement amount in correspondence with the movement value of the SOC-OCV characteristic, and indicates a change in movement value per 1% change in ΔSOC.

  Next, the downward correction coefficient will be described. In the SOC-OCV characteristics, OCV shows a lower value on the discharge side than on the charge side, and even when the current integration amount is the same at the time of charging and discharging, the variation at the time of discharging is larger than that at the time of charging. Become. Therefore, a downward correction coefficient is used to accelerate the amount of movement during discharge.

The SOC is normally calculated by the following equation using the full charge capacity as the denominator and the accumulated current amount as the numerator.
SOC = initial SOC + current integrated amount / full charge capacity (Equation 3)
However, since the discharge capacity is smaller than the charge capacity, if the current integration amount equal to the current integration amount of 10% SOC change during charging is discharged, the full charge capacity, which is the denominator of the above equation, is Since it becomes smaller, the SOC fluctuation at the time of discharge becomes 10% or more. This fluctuation depends on the charge / discharge efficiency of the secondary battery and is a value specific to the battery. However, 1/10 of the known charge / discharge efficiency of 99.5% is used as the degree of influence on the downward correction, and 1.0005 is used. It can be determined as a downward correction factor.

  Next, the number of divisions of the SOC-OCV characteristic area will be described. In the above-described embodiment, the three SOC-OCV characteristics 1-1, 1-2, and 1-3 are included in the SOC-OCV characteristic region surrounded by the full charge characteristic 5-1 and the complete discharge characteristic 5-2. A curve was added to divide the SOC-OCV characteristic area into four.

  The number of divisions depends on the required accuracy. Now, assuming that the required accuracy is 1%, and the maximum SOC deviation is 4% between the full charge characteristic 5-1 and the complete discharge characteristic 5-2, the area of the maximum deviation 4% is divided into four. Thus, it is possible to estimate the SOC with the required accuracy of 1% by estimating the SOC with the SOC-OCV characteristics in increments of 1%.

  When the current integration error generated due to a current sensor or an A / D conversion error exceeds 1%, the number of SOC-OCV characteristics to be added is reduced. For example, when the maximum deviation is 4% and the current integration error is larger than 1.5%, the total number of SOC-OCV characteristics is set to 4, the number of divisions is reduced to 3, and the area of maximum deviation 4% is divided into 3 1.3% (= 4% ÷ 3).

  Next, the SOC-OCV characteristic table will be described in detail. In the SOC-OCV characteristic table, discrete OCV values are arranged in the horizontal direction, and SOC values are mapped to the respective OCV values. When the voltage of the secondary battery is measured, an intermediate value finer than the value of each OCV in the SOC-OCV characteristic table is detected. For the intermediate value of the OCV, the SOC value can be supplemented by linear interpolation. On the other hand, since the vertical movement value of the SOC-OCV characteristic table is related to the number of divisions described above, linear interpolation of the SOC-OCV characteristic is not performed on the movement value.

  Next, the movement amount of the SOC-OCV characteristic will be described in detail. In the above-described embodiment, a total of five SOC-OCV characteristics are used as SOC-OCV characteristics to be used for estimating the SOC, and a movement amount based on current integration by charging / discharging is calculated. Among the five SOC-OCV characteristics, the movement value is calculated. Selects the one close to the amount of movement. When the movement amount is ± 1 or more, it is handled as a movement value ± 1. Therefore, the SOC-OCV characteristic used for estimating the SOC does not extend beyond the region surrounded by the full charge characteristic 5-1 and the complete discharge characteristic 5-2, and the estimated value of the SOC is deteriorated from the conventional estimated value. There is nothing.

  Here, the above-described operation will be described using specific numerical examples. Now, it is assumed that discharge is performed with the point Q in FIG. 1 as a starting point. It is assumed that the point Q is on the full charge characteristic 5-1 (movement value: +1), the OCV is 4.047 V, and the SOC is 95.02% (see Table 1). Then, it is assumed that the SOC change ΔSOC due to discharge is calculated as 4.98% by the above-described (Equation 1).

Then, according to the above (Equation 2), the movement amount is
Movement amount = 1-5 x (1 / 8.1) x 1.0005 = 0.3824
Is calculated as

  Of the movement values (+1, +0.5, 0, −0.5, −1) which are discrete values, it is determined which movement value is the closest to the movement amount 0.3824, and the closest movement Select the value +0.5. Accordingly, the SOC-OCV characteristic 1-1 having a movement value of 0.5 is used, and the SOC-OCV characteristic table of Table 1 is referred to the SOC-OCV characteristic having a movement value of 0.5, and the OCV value is calculated. The SOC is obtained.

  Next, aged deterioration of the secondary battery will be described. The secondary battery changes its SOC-OCV characteristics due to aging. Therefore, it is necessary to correct the mapping data of the SOC-OCV characteristic according to the deterioration state. In order to perform this correction, a deterioration map for each deterioration year is prepared.

  An example of the deterioration map is shown in Table 2.

劣化マップの横方向にはＯＣＶの値に応じた劣化係数を配列し、縦方向には劣化年数に応じた劣化係数配列する。該劣化マップの係数をＳＯＣ−ＯＣＶ特性のマッピングデータに乗じることにより、劣化に対する補正を行う。劣化マップは各ＳＯＣ−ＯＣＶ特性５−１、５−２、１−１、１−２、１−３毎に保管することとする。

Degradation coefficients corresponding to the OCV values are arranged in the horizontal direction of the deterioration map, and deterioration coefficients are arranged in the vertical direction according to the deterioration years. The deterioration is corrected by multiplying the mapping data of the SOC-OCV characteristic by the coefficient of the deterioration map. The deterioration map is stored for each SOC-OCV characteristic 5-1, 5-2, 1-1, 1-2, 1-3.

  An example of the flow of selecting the above-mentioned SOC-OCV characteristic and selecting the deterioration map is shown in FIGS. As shown in FIG. 2, it is determined whether the secondary battery is being charged or discharged (S2-1, S2-2). In the case of charging, the movement amount due to current integration at the time of charging is calculated by setting the downward correction coefficient of the above (Equation 2) to 1 (S2-3). In the case of discharging, the movement amount due to current integration during discharging is calculated by setting the downward correction coefficient of the above-described (Equation 2) to 1.0005 (S2-4). If it is neither charging nor discharging, the movement amount is not changed, and the previous movement amount is held (S2-5).

  Next, it is determined whether the movement amount is less than -0.75, -0.75 or more and less than -0.25, -0.25 or more and less than 0.25, or 0.25 or more and less than 0.75 (S2 -6 to S2-9). When the movement amount is less than -0.75, the SOC-OCV characteristic of the movement value -1 is selected (S2-10). When the movement amount is -0.75 or more and less than -0.25, the SOC-OCV characteristic having a movement value of -0.5 is selected (S2-11). When the movement amount is -0.25 or more and less than 0.25, the SOC-OCV characteristic with the movement value 0 is selected (S2-12). When the movement amount is not less than 0.25 and less than 0.75, the SOC-OCV characteristic having a movement value of 0.5 is selected (S2-13). When the amount of movement is other than that, the SOC-OCV characteristic of the movement value 1 is selected (S2-14).

  Next, the deterioration of the secondary battery is estimated. As in the example illustrated in FIG. 3, it is determined whether the age of the secondary battery is 0 years, 1 year, n years, or 9 years (S3-1 to S3-4). When the deterioration year is 0 years, the deterioration map of year 0 is selected (S3-5). When the deterioration year is 1 year, the deterioration map of year 1 is selected (S3-6), and the deterioration year is n years. If the deterioration year is 9 years, select the deterioration map of year 9 (S3-8), otherwise select the deterioration map of year 10 (S3-8). (S3-9). FIG. 3 shows an example in which the deterioration map is prepared for 10 years, but how many years the deterioration map is prepared is appropriately selected depending on the performance of the secondary battery and the like.

  In the deterioration map, a deterioration coefficient for reducing the SOC value of the SOC-OCV characteristic table due to aging deterioration is mapped. The SOC-OCV characteristic table corresponding to the deterioration years is created by multiplying the deterioration coefficient of the deterioration map selected according to the deterioration years by the SOC value of the SOC-OCV characteristic table (S3-10).

  The SOC value is estimated based on the measured OCV value using the SOC-OCV characteristic selected by the movement amount according to the flow of FIG. 2 described above and the deterioration estimated by the flow of FIG. 3 (S-11). It should be noted that the age of deterioration can be determined by deterioration estimation using a current value measured in synchronization with the battery voltage.

  FIG. 4 shows a functional block configuration example of the SOC estimation apparatus that selects the above-described SOC-OCV characteristic. The SOC estimation device includes a table storage unit 4-1, a movement amount calculation unit 4-2, an SOC-OCV characteristic selection unit 4-3, an SOC-OCV characteristic deterioration estimation unit 4-4, and an SOC estimation unit 4-5. .

  The SOC-OCV characteristic table storage unit 4-1 stores mapping data of at least one SOC-OCV characteristic that divides between the full charge characteristic 5-1 and the complete discharge characteristic 5-2. The movement amount calculation unit 4-2 includes a movement value held in the movement value holding unit 4-6 selected last time, a current integration amount of charge / discharge measured by the current integration amount measurement unit 4-7, and a movement coefficient. Using the movement coefficient held in the holding unit 4-8 and the lower correction coefficient held in the lower correction coefficient holding unit 4-9, the movement amount of the SOC-OCV characteristic is calculated by the above-described (Equation 2). To do.

  The SOC-OCV characteristic selection unit 4-3 determines the movement value closest to the movement amount calculated by the movement amount calculation unit 4-2, and selects the SOC-OCV characteristic of the movement value. The SOC-OCV characteristic deterioration estimation unit 4-4 reads a deterioration map corresponding to the deterioration year of the secondary battery to be estimated from the deterioration map storage unit 4-10, and calculates the deterioration coefficient of the deterioration map of the SOC-OCV characteristic. The mapping data is multiplied to generate an SOC-OCV characteristic whose deterioration has been estimated.

  The SOC estimation unit 4-5 is a value of the measured OCV using the SOC-OCV characteristic selected by the SOC-OCV characteristic selection unit 4-3 and estimated by the SOC-OCV characteristic deterioration estimation unit 4-4. From this, the SOC value is estimated.

  The embodiments of the SOC estimation apparatus and the SOC estimation method of the present invention have been described based on the examples. However, the present invention is not limited to the above-described embodiments and does not depart from the gist of the present invention. Various configurations or embodiments may be taken within.

4-1 SOC-OCV characteristic table storage unit 4-2 Movement amount calculation unit 4-3 SOC-OCV characteristic selection unit 4-4 SOC-OCV characteristic deterioration estimation unit 4-5 SOC estimation unit 4-6 Previously selected movement value Holding unit 4-7 Current integration amount measuring unit 4-8 Movement coefficient holding unit 4-9 Downward correction coefficient holding unit 4-10 Degradation map storage unit

Claims (8)

In the state of charge estimation device for estimating the state of charge (SOC) based on the SOC-OCV characteristics from the open circuit voltage (OCV) of the secondary battery,
SOC-OCV characteristics (hereinafter referred to as “full charge characteristics”) when charging from a fully discharged state to a fully charged state, and SOC-OCV characteristics (hereinafter referred to as “complete discharge characteristics”) when discharging from a fully charged state to a fully discharged state. A plurality of SOC-OCV characteristics including at least one SOC-OCV characteristic that divides a region between the full charge characteristic and the full discharge characteristic, and for each SOC-OCV characteristic SOC-OCV characteristic table to which the movement value is given,
Movement amount calculation means for calculating the movement amount of the SOC-OCV characteristic according to the current accumulation amount based on the current accumulation amount due to charging / discharging and the movement value of the SOC-OCV characteristic used immediately before the charging / discharging. When,
A SOC-OCV characteristic selection unit that determines a movement value closest to the movement amount calculated by the movement amount calculation unit, and selects an SOC-OCV characteristic of the movement value from the plurality of SOC-OCV characteristics;
SOC estimation means for estimating the SOC value from the measured OCV value using the SOC-OCV characteristic selected by the SOC-OCV characteristic selection means;
A charging state estimation device comprising:   2. The movement amount calculation unit performs an operation of moving the movement amount of the SOC-OCV characteristic downward with respect to the current integration due to discharging as compared with the current integration due to charging. Charge state estimation device.   The movement amount calculating means multiplies the change amount of the SOC due to charge / discharge current integration by a movement coefficient for normalizing the movement amount in correspondence with the movement value of the SOC-OCV characteristic, and the multiplication at the time of discharge. Is multiplied by a downward correction coefficient for moving the SOC-OCV characteristic downward, and the movement value of the SOC-OCV characteristic used immediately before the charge / discharge is increased or decreased by the value of the multiplication, The charge amount estimation apparatus according to claim 1, wherein the movement amount is calculated.   SOC-OCV characteristic deterioration estimation means for generating an SOC-OCV characteristic obtained by multiplying the SOC-OCV characteristic selected by the SOC-OCV characteristic selection means by a deterioration coefficient corresponding to the deterioration year of the secondary battery, 4. The state of charge according to claim 1, wherein the SOC estimation unit estimates the value of the SOC using the SOC-OCV characteristic generated by the SOC-OCV characteristic deterioration estimation unit. Estimating device. In the state of charge estimation method for estimating the state of charge (SOC) based on the SOC-OCV characteristics from the open circuit voltage (OCV) of the secondary battery,
SOC-OCV characteristics (hereinafter referred to as “full charge characteristics”) when charging from a fully discharged state to a fully charged state, and SOC-OCV characteristics (hereinafter referred to as “complete discharge characteristics”) when discharging from a fully charged state to a fully discharged state. A plurality of SOC-OCV characteristics including at least one SOC-OCV characteristic that divides a region between the full charge characteristic and the full discharge characteristic, and for each SOC-OCV characteristic Using the SOC-OCV characteristic table to which the movement value is given,
Based on the current accumulated amount due to charging / discharging and the movement value of the SOC-OCV characteristic used immediately before the charging / discharging, the movement amount of the SOC-OCV characteristic corresponding to the current accumulated amount is calculated,
Determining a movement value closest to the calculated movement amount, and selecting an SOC-OCV characteristic of the movement value from the plurality of SOC-OCV characteristics;
A state of charge estimation method, wherein the SOC value is estimated from the measured OCV value using the selected SOC-OCV characteristic.   6. The calculation of the movement amount according to claim 5, wherein the movement amount is calculated by moving the movement amount of the SOC-OCV characteristic downward with respect to the current integration due to the discharge as compared with the current integration due to the charging. Charge state estimation method.   The movement amount is calculated by multiplying the change in the SOC due to charge / discharge current integration by a movement coefficient that normalizes the movement amount in correspondence with the movement value of the SOC-OCV characteristic, and the multiplication at the time of discharge. Is multiplied by a downward correction coefficient for moving the SOC-OCV characteristic downward, and the movement value of the SOC-OCV characteristic used immediately before the charge / discharge is increased or decreased by the value of the multiplication, The charge state estimation apparatus according to claim 5, wherein the movement amount is calculated.   An SOC-OCV characteristic obtained by multiplying the selected SOC-OCV characteristic by a deterioration coefficient corresponding to the age of the secondary battery is generated, and the SOC-OCV characteristic obtained by multiplying the deterioration coefficient is used. The charge state estimation method according to claim 5, wherein a value is estimated.

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