JPH05142313A - Open circuit voltage estimation device for lead-acid battery - Google Patents

Abstract

PURPOSE:To provide an open circuit voltage estimation device for a lead-acid battery, for estimating open circuit voltage from the measurement data of voltage as well as current during electrification, without breaking a battery circuit. CONSTITUTION:Detection circuits (12a, 12b) for measuring current Ij and terminal voltage Vj from a lead-acid battery PB that is being discharged, and a first calculation circuit 14, are provided, by which the terminal voltage Vj is estimated based on the current Ij, through a first relational expression including a constant term correspondent to the open circuit voltage of the lead-acid battery PB and a coefficient term relating to the current Ij, by which a difference between the estimated terminal voltage and the measured terminal voltage is calculated, by which calculation is carried out by changing the coefficient term so that the terminal voltage estimated based on the difference is similar to the measured one, and by which outputting is carried out on the ground that the estimated terminal voltage and the measured one match with one another, and that the constant when an input current is zero is the open circuit voltage of the lead-acid battery PB.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for estimating an open circuit voltage of a lead storage battery used as a power source for an electric vehicle.

[0002]

2. Description of the Related Art Conventionally, lead acid batteries have been used as a power source for electric vehicles.

This lead-acid battery is excellent in terms of life and price, but has a small storage capacity in one charge, so that when it is used as a power source for an electric vehicle, the traveling distance is shortened. The current situation is that charging is not easy because the charging place is limited.

Therefore, when using a lead-acid battery,
It is necessary to be able to accurately estimate the travelable distance at a desired time point, and therefore, it is important to accurately grasp the remaining capacity of the lead storage battery.

In order to accurately grasp this state of charge, the open circuit voltage corresponding to the electromotive force of the battery, which is one of the indexes showing the performance of the lead storage battery, is used as a standard.

By the way, a lead-acid battery has a large voltage drop due to discharge, and it takes a long time to recover the voltage after the voltage drop due to a chemical reaction and a diffusion phenomenon. After stopping the discharge to stop the voltage drop, it was necessary to wait for a long time until the voltage gradually recovered.

Therefore, it is conceivable to first cut off the battery circuit, measure the change in the terminal voltage for a short time after the interruption of the discharge, and estimate the open circuit voltage from the measurement result.

However, in the measurement, it is necessary to actually cut off the battery circuit, and the car stops due to the cutoff. Therefore, it is not possible to perform the measurement in a place where the traffic is heavy. was there.

Therefore, it is desired that the open circuit voltage can be estimated without interrupting the battery circuit.

[0010]

However, when the battery circuit is not cut off, the measured terminal voltage often fluctuates irregularly due to the influence of the current during discharging, and the open circuit voltage is calculated from these irregular data. There was a problem that it was difficult to estimate.

The present invention has been made in view of the above problems, and an object thereof is to estimate an open circuit voltage from measured data of a voltage and a current during energization without interrupting a battery circuit. An object of the present invention is to provide a lead-acid battery open-circuit voltage estimation device that is capable of performing the above.

[0012]

In order to achieve the above object, an open circuit voltage estimating apparatus for a lead storage battery according to the present invention includes a detecting means for actually measuring a current and a terminal voltage from a discharging lead storage battery, and Based on the above, the terminal voltage is estimated by a first relational expression including a constant term corresponding to the open circuit voltage of the lead storage battery and a coefficient term relating to the current, and the difference between the estimated terminal voltage and the actually measured terminal voltage is calculated. Along with the calculation, the coefficient term is changed so as to approximate the terminal voltage estimated based on the difference to the measured terminal voltage, and the estimated terminal voltage and the measured terminal voltage match and are input. The present invention is characterized by having a first calculation means for outputting a constant component when the current is zero as an open circuit voltage of the lead storage battery.

[0013]

In the open-circuit voltage estimating device for a lead-acid battery having the above structure, the detecting means measures the current and the terminal voltage from the discharging lead-acid battery, and based on the measured current, the first calculating means detects the lead-acid battery The terminal voltage is estimated by the first relational expression including the constant term corresponding to the open circuit voltage and the coefficient term related to the current, and the difference between the estimated terminal voltage and the actually measured terminal voltage is calculated, and based on the difference. The coefficient term is changed to calculate the estimated terminal voltage to approximate the measured terminal voltage, and the constant is calculated when the estimated terminal voltage and the measured terminal voltage match and the input current is zero. Output is regarded as the open circuit voltage of the lead storage battery.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an open circuit voltage estimating apparatus for a lead storage battery according to the present invention will be described below with reference to the drawings.

A lead-acid battery open circuit voltage estimating apparatus 1 shown in FIG.
0 applies an adaptive digital filter (hereinafter abbreviated as ADF) 11 to estimate the open circuit voltage of the lead storage battery PB.

In FIG. 1, R is a load, and various electric parts such as an electric motor mounted on the electric vehicle correspond to the load R. Here, an equivalent model is used instead of the electric vehicle. I will explain using it.

FIG. 2 shows the main configuration of an experimental system based on the equivalent model.

(Outline of Experimental System) The experimental system is
It is a test device that uses running resistance as a simulated load, and has a control / measurement device via a personal computer. Here, 10 lead-acid batteries PB connected in series are used as a drive power source for the test apparatus (hereinafter referred to as an EV drive tester), and the EV drive tester runs under the load of the generator by the generator operation of the electric motor M. It simulates resistance.

The electric motor M is composed of two direct current electric motors (DCM) M1,
M2 and one AC motor (ACM) M3 are provided, and each motor M1, M2, M3 is connected to the universal FA system (U) via the direct digital control device (DDC).
FAS) respectively controlled. T is a torque meter.

The vehicle model and traveling pattern assumed in this experiment are shown below.

Vehicle model: An electric vehicle of a standard passenger car class with a weight of 1000 kg, which is 1 / th of a vehicle equipped with four electric motors M
There are four models.

Traveling pattern: The following pattern is repeatedly used based on a traveling pattern that is representative of urban driving.

Acceleration region The acceleration is 4 km / h / s.

Constant speed region The traveling speed is appropriately selected from the values of 10, 20, ..., 60 km / h, and the traveling time is 30 seconds.

Deceleration area Decelerate at a rate of 2 km / h / s.

Stopping period The vehicle is stopped for 30 seconds between runs.

(Outline of Adaptive Digital Filter) Next,
The basic model of the adaptive digital filter is shown in FIG.

In FIG. 3, xj and yj are input / output signals of the ADF 11, ej is an error signal with respect to the target value dj, and j is a time suffix. The non-recursive model given by Eq. (1) is used here.

[0029]

[Equation 1]

Here, N is the order of the filter, and bk, j is the weighting factor of the filter at time step j. The Feintuch algorithm given by the following equation is used for the coefficient estimation.

[0031]

[Equation 2]

Where v is a sufficiently small positive constant,
The step width in the steepest gradient method is shown.

Therefore, the calculation algorithm of ADF11 is
It is given in Steps 1 to 7 as follows.

Step1. Initial setting of v, bk, 0 (k = 0, ..., N) Step2. j = 0 (setting of initial time) Step3. Reading xj and dj Step4. yj = b0, j * xj + b1, j * xj-1 + ... + bN, j *
xj-N (calculation of predicted value) Step5. ej = dj-yj (calculation of error) Step6. bk, j + 1 = bk, j + v.ej.xj-k (parameter updating) Step7. j = j + 1, return to Step 3.

(ADF Open Circuit Voltage Prediction Model) As shown in FIGS. 4 and 5, the current Ij of the lead storage battery PB is the input digital value xj of the ADF 11 and the terminal voltage Vj is the target digital value yj of the ADF 11. The current Ij fluctuates and the terminal voltage Vj fluctuates according to the running condition.

FIG. 4 shows an equivalent circuit of the lead storage battery PB used as a power source for the EV drive tester, where r is the lead storage battery PB.
, E is an electromotive force. FIG. 5 is a chart used for explaining the identification of the lead storage battery model by the ADF 11, where xj is digital information of the input current Ij.

FIG. 6 shows the current Ij at this time and the lead storage battery PB.
It is an example of actual measurement of the terminal voltage Vj per one, and shows the states when the current increases, is constant, decreases, and has zero value, which correspond to the respective driving phases of the electric vehicle such as acceleration, constant speed, deceleration, and stop. There is. Here, it can be seen that the terminal voltage Vj fluctuates in a manner opposite to the increase and decrease of the current due to the influence of the internal resistance r of the lead storage battery PB and the like.

However, with Ij = I (jT) and Vj = V (jT), the sampling interval T is T = 0.756 seconds.

As described above, the current Ij and the voltage Vj are set to the ADF1.
As for the input and the target value of 1, the current Ij and the voltage Vj are related.
The ADF model is constructed as shown below.

[0040]

[Equation 3]

[0041]

[Equation 4]

[0042]

[Equation 5]

However, ej = Vj-Vj ', and Vj' is Vj
The predicted value of is shown.

In this embodiment, a constant term Cj is newly added to the equation (1) considering that the average value of voltage and current is not zero. However, w indicates the step width with respect to Cj.

As can be seen from the equation (3), Cj is the current I =
It corresponds to the voltage value at 0, that is, the estimated value of the open circuit voltage of the lead storage battery PB at the time jT. Hereinafter, this Cj will be regarded as the estimated open circuit voltage.

Next, in order to determine the order N of the model, the discharge of the lead storage battery PB was dispersed and calculated using the data of the 62nd cycle.
AIC was calculated and the results are shown in Table 1.

[0047]

[Table 1]

AIC indicates the Akaike information criterion and is represented by AIC = DN · log (variance) + 2 · (order). DN is the number of data, the variance is represented by Σej2 / DN, and the order is represented by N.

Here, the fact that the discharge is one cycle means a process until it becomes difficult to use the lead storage battery PB as a power source due to the discharge caused by the operation of the electric vehicle. The reason for choosing the data for the 62nd cycle is
This is because the discharge current of this cycle shows a considerably large value in various experimental data, and it is easy to verify the prediction accuracy of ADF11.

As can be seen from Table 1, when the order N = 2, both the variance and the AIC are the minimum, so the quadratic model given by the equation (6) (first relational equation) is adopted.

[0051]

[Equation 6]

That is, the predicted value Vj 'which is the estimated terminal voltage value at a certain time j is the current value Ij-2 at the time j-2 and the time j.
The current value Ij-1 at -1 and the current value Ij at time j are calculated.

However, the initial value of Cj is the initial value (12.598V) of the open circuit voltage that can be measured, and v = 0.0001, w = 0.0
I set it to 007.

FIG. 7 shows transitions of the coefficient bk, j and the constant term Cj when the terminal voltage Vj is predicted by this model.
The estimated value and the estimated error are shown in FIG.
(Result for 0 to 100 seconds), (b) (Result for 900 to 1000 seconds)
Shown in.

From these figures, it can be seen that the ADF model accurately estimates the terminal voltage, although the coefficient varies slightly.

(Estimation of open circuit voltage by ADF) It is confirmed that the constant term Cj in the equation (6) is appropriate as the estimated open circuit voltage.
Verify using the data of the cycle.

FIG. 9 shows the estimated open circuit voltage Cj together with the measured terminal voltage during discharge according to the time transition thereof. Here, ● indicates the maximum value of the measured terminal voltage within 300 steps, and ○ indicates the estimated open circuit voltage for each 300 steps.

The estimated open circuit voltage monotonously decreases at a level higher than the measured voltage with the lapse of discharge time, and is in good agreement with the generally-proposed open circuit voltage transition tendency with discharge.

Further, the comparison between the measured value and the calculated value of the final open circuit voltage at the 62nd cycle of discharge is as shown in the column of the final open circuit voltage in Table 1, and since the measured value is 12.101V, it is almost equal. I understand what you are doing.

In this way, by applying ADF11, the lead storage battery P
The open-circuit voltage, which is an index showing the performance of B, was estimated, and their effectiveness was quantitatively verified using experimental data.

As a result, by using ADF11,
It was found that the open circuit voltage can be estimated without interrupting the discharge of the lead acid battery PB.

Next, an embodiment of the open circuit voltage estimating apparatus 10 for a lead storage battery based on the open circuit voltage prediction model by the ADF will be described.
A specific configuration will be described.

As shown in FIG. 1, the open-circuit voltage estimating apparatus 10 for a lead storage battery has an ADF 11 and a detection circuit for detecting discharge data of the lead storage battery PB as input information to the ADF 11.

The detection circuit measures the discharge data from the lead storage battery PB which is discharging by operating the electric motor M, and the current Ij
And a voltage detection circuit 12b for detecting the terminal voltage Vj.

The current Ij detected by the current detection circuit 12a is digitally converted via the A / D converter 13a and then output to the ADF 11, and the terminal voltage Vj detected by the voltage detection circuit 12b is A / D. After being digitally converted via the D converter 13b, it is output to the ADF 11.

The ADF 11 includes a first arithmetic circuit (first arithmetic means) 14, a comparison circuit 15, a judgment circuit 16 and a memory 17.
a and 17b.

Of the discharge data output to the ADF 11, A
The current information based on the current Ij output from the / D converter 13a is input to the first arithmetic circuit 14 as the input signal xj via the memory 17b.

On the other hand, the voltage information output from the A / D converter 13b is input to the comparison circuit 15 as the target value dj via the memory 17a.

Based on the input signal xj, the first arithmetic circuit 14 determines the constant term and the current Ij corresponding to the open circuit voltage of the lead storage battery PB.
The terminal voltage is estimated by the first relational expression (equation (6) above) including the coefficient term related to. The estimated terminal voltage is output to the comparison circuit 15 as the output signal yj of the first arithmetic circuit 14.

The comparison circuit 15 is the output signal yj of the first arithmetic circuit 14 and is the estimated value Vj 'which is the estimated terminal voltage.
And the target value dj which is the measured terminal voltage are compared,
The error signal ej which is the difference is output to the judgment circuit 16 and the first arithmetic circuit 14.

Based on the error signal ej fed back to the first arithmetic circuit 14, the first arithmetic circuit 14 changes the coefficient term so as to approximate the predicted value Vj 'to the target value dj, and calculates the predicted value Vj. ′ Is the output signal yj of the first arithmetic circuit 14.
Is output to the comparison circuit 15.

Further, based on the input error signal ej,
The determination circuit 16 determines whether or not the predicted value Vj 'and the target value dj match.

Then, from the comparison circuit 15 to the first arithmetic circuit 1
When the predicted value Vj 'and the target value dj substantially match with each other, the first arithmetic circuit 14 regards the constant Cj as the open circuit voltage of the lead storage battery PB and outputs it.

(Relationship between Open Circuit Voltage and Discharge Amount) By the way, in order to relate the estimated open circuit voltage to the remaining capacity (Wh) of the lead storage battery PB, it is necessary to investigate the relation between the open circuit voltage and the discharge amount. Is.

10 in FIG. 10 shows the relationship between the estimated open circuit voltage by the ADF 11 and the discharge amount. The estimated open circuit voltage monotonically decreases as the discharge progresses. To obtain an estimation formula that expresses the relationship between this discharge amount and the estimated open circuit voltage,
Perform data analysis by regression analysis and ADF modeling.

The value of each coefficient shown below is in units of discharge amount.
kWh, voltage unit is for V.

A: Regression analysis method The following quadratic regression equation is adopted in order to predict the discharge amount in consideration of the discharge amount and the estimated open circuit voltage tendency in FIG.

[0078]

[Equation 7]

Here, x is the discharge amount, y is the estimated open circuit voltage, αj, βj, γj are regression coefficients estimated from the data up to time jT, and are obtained by solving the following normal equations. Be done.

[0080]

[Equation 8]

[0081]

[Equation 9]

[0082]

[Equation 10]

Here, xi and yi represent the discharge amount and the estimated open circuit voltage at time iT, respectively.

Regarding the result of regression analysis by this method,
The regression curve is shown in the curve A of FIG. In addition, the regression coefficient and the estimation error at each time are shown in FIG.
It shows in (b).

From this result, it is understood that the relationship between the discharge amount and the estimated open circuit voltage can be approximated by the quadratic regression equation. At the end of discharge (J = 5290), the measured amount of discharge was 1488Wh,
The calculated discharge amount by the quadratic regression equation is 1545Wh.

However, in this regression analysis method, it is necessary to solve the equations (8) to (10) for each j, which requires a considerable calculation time.

In order to improve this point, a sequential calculation method based on the ADF modeling method is proposed below.

B: ADF modeling method As a result of the examination in the previous section, it was found that the relationship between the discharge amount and the estimated open circuit voltage can be approximated by a quadratic regression equation. Based on this result, we propose a method that applies the following ADF model suitable for sequential calculation.

[0089]

[Equation 11]

[0090]

[Equation 12]

[0091]

[Equation 13]

[0092]

[Equation 14]

[0093]

[Equation 15]

Here, Cj 'is the predicted value of the estimated open circuit voltage at time jT, Whj is the discharge amount at time jT, and fj, g
j, hj are weighting factors, and p, q, r are step widths when updating the weighting factors.

By using this method, the step width and the initial value of the coefficient were variously changed, and an estimated curve that accurately approximates the relationship between the discharge amount and the estimated open circuit voltage was obtained. The estimated curve was calculated as follows.

[0096]

[Equation 16]

The prediction result using the curve given by equation (15) is shown by curve B in FIG. 12A and 12B show the transitions of the coefficient and the error.

Curves A and B of FIG. 10 and equations (8) to (10)
Comparing Eqs. (11) to (14), it can be seen that the discharge amount estimation method using the ADF modeling method is superior to the regression analysis method in terms of calculation time and accuracy.

(Estimation of Remaining Capacity by Open Circuit Voltage) From the above examination, it became clear that the relationship between the estimated open circuit voltage and the discharge amount can be approximated by a quadratic expression of the discharge amount. Therefore, by using this quadratic equation, as shown in FIG. 13, the discharge amount corresponding to the difference between the current value of the estimated open circuit voltage and its limit value is defined as the remaining possible discharge amount (remaining capacity), and
Can be estimated.

Therefore, as described above, the ADF modeling method, which is easy to calculate, is applied to estimate the remaining capacity. in this case,
As shown in FIG. 12A, it is expected that the estimation accuracy is poor at the initial stage of discharge because the coefficient of the model is not stable.

Therefore, in the first half period including the initial stage of discharge, an average quadratic regression formula (hereinafter referred to as a reference formula) obtained by repeating discharges in the past is used as an estimation formula, and in the latter half period, the ADF model is used. The chemical method will be used.

That is, the remaining capacity is predicted by the following two-step estimation method of (A) and (B).

(A) Estimating the first period of discharge The estimation formula in the first period is the following equation (second relational equation).

[0104]

[Equation 17]

Here, V0 and Wh represent the estimated open circuit voltage and the discharge amount, respectively, and α, β, γ represent regression coefficients.

When the limit value of the open circuit voltage is V1, the total discharge amount Wht when the open circuit voltage reaches this limit value is (1
Substituting VO = V1 in equation (7),

[0107]

[Equation 18]

It is calculated by

Here, if the current discharge amount is Whn,
The remaining capacity Whr is given by the following equation.

[0110]

[Formula 19]

(B) Estimating in the latter half of discharge The estimation formula in the latter half of the discharge is (11) to (14) at the estimated calculation time jT.
Based on the ADF model estimated by the equation, the following equation (3rd relational equation)

[0112]

[Equation 20]

As in the case of (A), the remaining capacity is calculated by the following equation.

[0114]

[Equation 21]

[0115]

[Equation 22]

It should be noted that it is necessary to select the classification of the first half and the second half so that the estimated value of the remaining capacity does not change abruptly at the boundary of the division, and in this embodiment, the discharge period classification given in Table 2 is used.

[0117]

[Table 2]

Next, a specific example of the structure of the lead-acid battery remaining capacity estimating device 20 for predicting the remaining capacity by the two-step estimation method will be described.

The lead-acid battery remaining capacity estimation device 20 shown in FIG. 14 is based on the estimated open-circuit voltage output from the first arithmetic circuit 14 in addition to the lead-acid battery open circuit voltage estimation device 10 and the initial discharge stage of the lead-acid battery PB. The remaining capacity of the second relational expression ((1
7)) and the remaining capacity of the lead storage battery in the latter stage of discharge is estimated by the third relational expression (Equation (20)) and outputs the remaining capacity Whr to the second arithmetic circuit 21 (second arithmetic means). Have

(Results of Remaining Capacity Estimation) Here, a lead-acid battery PB is simulated by simulating a typical urban driving pattern of an electric vehicle.
Three cases (cases A, B, and
For the experimental data of C), the estimation is performed using the method proposed above, and its effectiveness is verified. Table 2 shows the discharge conditions and the constants used for the calculation in each case.

The estimation results of the remaining capacity for each of A, B and C cases are shown in FIGS.

As can be seen from these figures, in each case, the remaining capacity gradually decreases with the progress of discharge, while the total discharge capacity obtained by adding the already consumed discharge amount to this is approximately the final measurement in each case. It remains within ± 5% of the value.

It can be seen that the accuracy is particularly good in the case A (see FIG. 15) of the random traveling pattern which is considered to be close to the actual city traveling. It is also shown that substantially the same prediction accuracy can be obtained in case C (see FIG. 17) for high-speed operation.

In case B (see FIG. 16), the discharge is relatively slow, and the change in the open circuit voltage is gradual as compared with the tendency of the average reference formula. Therefore, the remaining capacity was calculated to be small in the previous period when the reference formula was applied to the estimation, and the total discharge amount decreased to about -10%.

By the way, in running an electric vehicle,
The accuracy of the latter half of discharge is important, and the error of 10% in the first half is not a very important problem for practical use.

Therefore, it is considered that the estimation of the remaining capacity by the remaining capacity estimation device for a lead storage battery according to the present invention is effective for various running patterns.

As described above, in order to grasp the remaining capacity of the lead storage battery, the ADF 11 is applied to estimate the open circuit voltage which is an index showing the performance of the lead storage battery PB. The effectiveness was quantitatively verified.

The contents are summarized as follows.

1. By using the ADF method, the open circuit voltage can be estimated without interrupting the discharge of the lead acid battery.

2. The estimated open circuit voltage has a correlation with the discharge amount of the lead storage battery, and can be approximated by a quadratic equation.

Using the quadratic equation of 3.2, the remaining capacity up to the usage limit of the lead storage battery can be accurately estimated from the estimated open circuit voltage during discharge and the discharge amount.

[0132]

According to the present invention, there is provided a lead-acid battery open circuit voltage estimating device which detects a current and a terminal voltage from a discharging lead-acid battery, and detects the terminal voltage based on the current. Estimated by the first relational expression including the constant term corresponding to the voltage and the coefficient term related to the current, the difference between the estimated terminal voltage and the measured terminal voltage is calculated, and the estimation is performed based on the difference. Calculate by changing the coefficient term to approximate the terminal voltage to the measured terminal voltage,
The present invention is characterized by having a first calculation means for outputting a constant amount when the estimated terminal voltage and the actually measured terminal voltage match and the input current is zero as the open circuit voltage of the lead storage battery.

Therefore, without interrupting the battery circuit,
The open circuit voltage can be estimated from the measured data of voltage and current during energization.

[Brief description of drawings]

FIG. 1 is a block diagram showing an open circuit voltage estimating apparatus for a lead storage battery according to the present invention.

FIG. 2 is an explanatory diagram showing a main configuration of an experimental system having an open circuit voltage estimation device for a lead storage battery.

FIG. 3 is an explanatory diagram showing a basic model of ADF.

FIG. 4 is an equivalent circuit diagram of a lead storage battery.

FIG. 5 is a chart used for explaining identification of a lead storage battery model by ADF.

FIG. 6 is a diagram showing an actual measurement example of the current shown in FIG. 3 and the terminal voltage per battery.

FIG. 7 is a diagram showing changes in coefficients and constant terms when a terminal voltage is predicted by an open circuit voltage model using ADF.

FIG. 8 shows a case where a terminal voltage is predicted by an open circuit voltage model using ADF, (a) is a diagram of predicted values,
(B) is a figure of a prediction error.

FIG. 9 is a diagram showing a time transition of an estimated open circuit voltage and a measured voltage value.

FIG. 10 is an explanatory diagram showing a main configuration of an experimental system having an open circuit voltage estimation device for a lead storage battery.

FIG. 11 is an explanatory diagram showing a basic model of ADF.

FIG. 12 is an equivalent circuit diagram of a lead storage battery.

FIG. 13 is a chart used for explaining identification of a lead storage battery model by ADF.

FIG. 14 is a block diagram showing a remaining capacity estimation device for a lead storage battery.

FIG. 15 is a diagram showing an actual measurement example of the current shown in FIG. 3 and the terminal voltage per battery.

FIG. 16 is a diagram showing changes in coefficients and constant terms when a terminal voltage is predicted by an open circuit voltage model using an ADF.

FIG. 17 shows a case where the terminal voltage is predicted by an open circuit voltage model using ADF, (a) is a diagram of predicted values,
(B) is a figure of a prediction error.

[Explanation of symbols]

 10 Open Circuit Voltage Estimating Device for Lead Acid Battery 12a Detection Circuit (Detection Means) 12b Detection Circuit (Detection Means) 14 First Operation Circuit (First Operation Means) PB Lead Acid Battery Ij Current Vj Terminal Voltage

[Procedure amendment]

[Submission date] November 20, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0097

[Correction method] Change

[Correction content]

The result of prediction using the curve given by equation (16) is shown by curve B in FIG. 12A and 12B show the transitions of the coefficient and the error. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 27, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] Figure 9

[Correction method] Change

[Correction content]

[Figure 9]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumihiko Ishikawa 2869-4, 7 wards, Kita-cho, Takamatsu-shi, Kagawa (72) Inventor Shigenori Matsumura 2--12-26, Kaminocho, Takamatsu-shi, Kagawa (72) Inventor Takao Marui 2-10-40 Sonenishi-cho, Toyonaka-shi, Osaka Prefecture (72) Masamichi Inakura 1-33-15-15 Hirose, Shimamoto-cho, Mishima-gun, Osaka Prefecture Inventor Shigeru Omatsu 2-9, Nakajojo-shima, Tokushima-shi, Tokushima Prefecture

Claims (1)

[Claims] 1. A detecting means for actually measuring a current and a terminal voltage from a discharging lead acid battery, a constant term corresponding to the open circuit voltage of the lead acid battery and a coefficient term relating to the current, based on the current. Estimated by a first relational expression including and calculating the difference between the estimated terminal voltage and the measured terminal voltage, and approximating the terminal voltage estimated based on the difference to the measured terminal voltage, A first computing means for computing by changing the coefficient term, and regarding the constant when the estimated terminal voltage and the actually measured terminal voltage match and the input current is zero as the open circuit voltage of the lead storage battery and outputting the result. An open circuit voltage estimating apparatus for a lead storage battery, comprising: