JP5393182B2 - Battery internal resistance component estimation method and charge capacity estimation method - Google Patents

Description

  The present invention belongs to the technical field of an internal resistance component estimation method and a charge capacity estimation method for a battery constituted by a plurality of unit battery cells.

  Conventionally, a secondary battery is represented by an equivalent circuit consisting of an electromotive force, an electrolyte resistance, a positive and negative electrode resistance, and an electrode capacitor component. (For example, refer to Patent Document 1).

In addition, there is a case in which the internal resistance value of each cell is calculated using only the DC resistance component by using the current value and voltage value of each cell accumulated in a plurality of measurements (see, for example, Patent Document 2). ).
In addition, when performing charging / discharging, there is one in which one of current and voltage is changed in a stepped shape or a rectangular wave shape, and the capacitor component is measured by the internal resistance of the secondary battery (see, for example, Patent Document 3). .

JP 2000-1333322 A (page 2-4, all figures) JP 2004-28861 A (page 2-9, full view) JP 2006-162283 A (page 2-29, full view)

However, conventionally, the calculation error of the internal resistance is large, and the calculation error of SOC (State of charge, hereinafter abbreviated as SOC), which is the battery capacity calculated using the internal resistance, is large.
In addition, it is difficult to accurately measure the internal resistance according to Japanese Patent Application Laid-Open No. 2006-162283 of the above-mentioned conventional publication due to fluctuations in current and voltage during operation.

  The present invention has been made paying attention to the above-mentioned problems, and the object of the present invention is to improve the accuracy of the internal resistance estimation value, and thus to improve the accuracy of calculating the SOC, which is the battery capacity. An object is to provide an internal resistance component estimation method and a charge capacity estimation method.

In order to achieve the above object, according to the present invention, there is provided a method for estimating an internal resistance component of a battery composed of a plurality of unit battery cells, wherein the internal resistance component of the battery is unevenly distributed due to diffusion movement of ionic substances inside the battery. In the battery internal resistance component estimation method for estimating the diffusion polarization resistance by setting the diffusion polarization resistance in consideration of the voltage generated in the step and using the change in the concentration of the diffusion material over time , the diffusion polarization resistance is supplied by the battery. A current value to be detected, divided into a plurality of time intervals by a sign change of the detected current, an average current Ia in each time interval is calculated, and a saturation polarization voltage ΔVo of the average current Ia is calculated from a previously obtained relationship, Using the curve f (t) calculated from the solution of the diffusion equation, the diffusion polarization toward the saturation polarization voltage ΔVo in the direction in which the potential difference is large in the positive or negative direction with time. The progress changes, calculated as a diffusion polarization voltage ΔVa just before the sign of the detected current for each said time interval is changed, and performing the estimation.

  Therefore, according to the present invention, the accuracy of the internal resistance estimation value can be improved, and as a result, the calculation accuracy of the SOC that is the battery capacity can be improved.

It is a block diagram which shows the structure of the battery apparatus using the internal resistance component estimation method and charging capacity estimation method of the battery of Example 1. 3 is a flowchart showing a flow of calculation processing of battery capacity SOC using the battery internal resistance component estimation method of Embodiment 1; It is a flowchart which shows the flow of the calculation process of the diffusion polarization voltage in step S9 of FIG. It is explanatory drawing of the spreading | diffusion state which has arisen inside the battery. It is explanatory drawing of the diffusion state with progress of time. It is a diagram showing an example of the experimental waveforms for determining the ΔVo and L / D ^0.5. It is explanatory drawing of the state which a substance density | concentration decreases with time by diffusion and reaction. It is a graph which shows the relationship between the curve before correction | amendment and after correction | amendment. It is explanatory drawing which shows an example of the experimental waveform which determines a correction coefficient. It is a graph which shows the relationship between temperature and the temperature coefficient computed from the Arrhenius rule. It is a graph which shows the example of the battery current change measured with the sensor. It is a graph which shows the average electric current computed from the battery electric current measured with the sensor. It is a graph which shows the relationship between an average electric current and (DELTA) Vo. It is a graph which shows the polarization voltage computed from the solution of the average current and the diffusion equation. It is a graph which shows the calculation state of a polarization voltage. It is a graph which shows the example of the relationship between an average electric current and a correction coefficient. It is explanatory graph figure of polarization voltage ((DELTA) Vb) computed from (DELTA) V and the solution of a diffusion equation. It is a graph of the state which calculates polarization voltage ((DELTA) Vb). It is explanatory drawing which shows the calculation state of polarization voltage (DELTA) V. It is explanatory drawing of the circuit of the battery containing internal resistance. It is explanatory drawing of a current-voltage characteristic. It is a graph which shows the relationship between a battery open circuit voltage and SOC. It is a figure of the equivalent circuit of the battery containing polarization resistance. It is a graph which shows the current voltage characteristic containing polarization resistance. It is explanatory drawing which shows the state inside a lithium ion secondary battery. It is a graph which shows the change state of the electric current and voltage at the time of direct-current internal resistance measurement. It is explanatory drawing of DC internal resistance of a battery, and a measurement circuit. It is a graph which shows the change state of the electric current at the time of direct current | flow internal resistance measurement when sampling time is considered. It is a flowchart which shows the calculation process of the direct current | flow resistance R part performed by step S9 of FIG. It is a figure which shows the equivalent circuit of the battery of only DC resistance. It is a figure which shows the equivalent circuit of the battery which added the polarization resistance component. It is a time chart which shows the difference of the equivalent circuit of a battery, and a voltage change. It is a time chart which shows the difference of the equivalent circuit of a battery, and Eo estimated value. It is a time chart which shows the characteristic which diffusion polarization cancels. 6 is a graph showing an example of battery current change measured by a sensor in Example 2. FIG. It is a graph which shows the average electric current computed from the battery electric current measured with the sensor in Example 2. FIG. It is a graph which shows the relationship between the average electric current of Example 2, and time. It is a graph which shows the calculation state of the polarization voltage of Example 2. FIG. In Example 2, it is a graph which shows the state which computed the calculated polarization voltage from the solution of the average current and the diffusion equation. It is explanatory graph figure of the polarization voltage ((DELTA) Vb) computed from (DELTA) V in Example 2, and the solution of a diffusion equation. It is a graph of the state which calculates the polarization voltage ((DELTA) Vb_n) in Example 2. FIG. It is explanatory drawing which shows the calculation state of voltage (DELTA) V by the polarization in Example 2. FIG. It is explanatory drawing which shows the calculation state of polarization voltage (DELTA) V_n in Example 2. FIG. It is a block diagram which shows the structure of the battery apparatus using the internal resistance component estimation method and discharge capacity estimation method of the battery of Example 3. It is a block diagram which shows the control structure which performs the internal resistance component estimation method and discharge capacity estimation method of the battery of Example 3. 10 is a flowchart illustrating a flow of a usable time calculation process executed by the battery controller 2 according to the third embodiment. FIG. 10 is an explanatory diagram showing a calculation state of a battery capacity calculation voltage Vc in Example 3. FIG. 10 is an explanatory diagram showing a calculation state of a usable battery full capacity in Example 3. 6 is a graph showing a discharge curve at 20 ° C. in Example 3. FIG. 6 is a graph showing a discharge curve at 0 ° C. in Example 3. FIG. It is explanatory drawing which shows the circuit whose internal resistance is only DC resistance. It is a graph which shows the discharge curve when internal resistance considers only DC resistance. It is explanatory drawing which shows the circuit set in Example 3 whose internal resistance consists of DC resistance and polarization resistance. It is a graph of the discharge curve in the case of Example 3 whose internal resistance contains polarization resistance.

  Hereinafter, the embodiment for realizing the battery internal resistance component estimation method of the present invention will be described with reference to the first embodiment corresponding to the inventions according to claims 1 to 6 and the implementation corresponding to the inventions according to claims 1 to 8. Description will be made based on Example 2 and Example 3 corresponding to the inventions according to claims 1 to 7 and 9.

First, the configuration will be described.
FIG. 1 is a block diagram illustrating a configuration of a battery device using the battery internal resistance component estimation method and the charge capacity estimation method according to the first embodiment.
The battery device 1 according to the first embodiment includes a battery controller 2, a voltage sensor 3, a current sensor 4, a battery 5, a load 6, and a temperature sensor 7.
The battery controller 2 calculates the total capacity of the battery 5 (battery capacity), input / output possible power, and the like.
The voltage sensor 3 measures the voltage output from the battery 5.
The current sensor 4 measures the current output from the battery 5.
The battery 5 is formed by connecting a plurality of unit battery cells, for example, several tens, for example, and is described as the battery 5 in the present specification. In Example 1, it is set as a lithium ion battery.
The temperature sensor 7 measures the battery temperature of the battery 5.

The operation will be described.
[Battery capacity SOC calculation]
FIG. 2 is a flowchart showing the flow of the battery capacity SOC calculation process using the battery internal resistance component estimation method according to the first embodiment. Each step will be described below.
In step S <b> 1, the voltage value V and the current value I are input from the voltage sensor 3 and the current sensor 4. The current sensor detects the discharge current as negative and the charge current as positive.

  In step S2, it is determined whether or not there is a current change that can calculate the internal resistance R and the diffusion polarization voltage ΔV, which is a voltage drop caused by polarization, and if there is a sufficient current change, the process proceeds to step S9, where a sufficient current change occurs. If not, the process proceeds to step S3.

  In step S3, a new internal resistance value of the battery 5 is obtained by an experiment or the like and recorded in a memory (not shown), and a value obtained by multiplying the read new internal resistance of the battery 5 by a deterioration coefficient and a temperature coefficient is obtained. The internal resistance value R ′ of the battery is calculated, and the process proceeds to step S4. The deterioration coefficient can be obtained from an IV line obtained by linearly approximating the voltage value V and the current value I sampled a plurality of times, and the temperature coefficient is based on the correlation between the temperature and the temperature coefficient obtained in advance by experiments. Can be obtained.

In step S4, the voltage value V and current value I input in step S1, the internal resistance value R ′ calculated in step S3, or the internal resistance R calculated in step S9 described later, and the diffusion polarization voltage ΔV Based on the above, the open circuit voltage of the battery is calculated.
(Equation 1)
Eo = V-IR-ΔV (the sign of ΔV is the same as I)

  In step S5, the reset target SOC (%) is calculated from the battery open voltage Eo by referring to the table. The table is a table showing the correlation between the battery open voltage Eo and the battery SOC (%) obtained in advance through experiments or the like.

  In step S6, the sensor current is integrated and current integration SOC (%) is calculated. That is, the voltage when the charge / discharge current at the time of starting the system is 0 (that is, when the battery is not loaded) is detected, and the detected voltage is set as the open circuit voltage Eo, and the SOC (%) is referenced with reference to the table used in step S5. Thereafter, a value obtained by converting the integrated value of the sensor current from the time of starting the system into SOC (%) is added to or subtracted from the SOC (%) at the time of starting the system to obtain the current integrated SOC.

  In step S7, as the SOC reset process, the current integrated SOC (%) is increased or decreased to approach the reset target SOC (%). That is, when there is a difference between the current integrated SOC and the reset target SOC, the current integrated SOC is corrected so as to approach the reset target SOC within a range equal to or less than a predetermined upper limit correction value.

  In step S8, the battery capacity SOC (%) calculated in step S7 is output to an input / output management unit (not shown) that calculates input / output possible power.

  In step S9, the internal resistance R is calculated from the current and voltage change, and the polarization voltage increases from the average current from the previous charge / discharge switching (switching from charge to discharge or discharge to charge) to the current charge / discharge switching. The amount ΔVa that changes in the direction is calculated, the amount ΔVb in which the polarization voltage changes in the decreasing direction from the average current is calculated, and the diffusion polarization voltage ΔV is calculated from ΔVa and ΔVb.

  In step S10, the deterioration state of the battery is determined from the calculated internal resistance R, and the internal resistance R is stored in the internal memory of the battery controller 2 or the like.

  In step S11, it is determined whether or not a shutdown process for ending the SOC calculation process is performed. If the shutdown process is performed, the SOC calculation process is terminated. If the shutdown process is not performed, the process returns to step S1.

[Diffusion polarization voltage calculation]
FIG. 3 is a flowchart showing the flow of the diffusion polarization voltage calculation process in step S9 of FIG. 2, and each step will be described below.

  In step S91, the time with the same sign of the current is calculated from the change in the sensor current. For example, t1, t2, t3, t4 in FIG.

  In step S92, the average current during the time tx is calculated and set as Ia. For example, the time tx is, for example, t1, t2, t3, t4 in FIG.

  In step S93, ΔVa at time tx is calculated from the average current Ia using f (t).

  In step S94, ΔVb is calculated using f (t) with the previous value (tx−1) of ΔV as an initial value.

  In step S95, ΔV between the times tx is calculated. If a plurality of times tx are obtained, steps S93 → S94 → S95 are repeated correspondingly. For example, ΔV is calculated for each of t1 to t4 in the case of FIG.

[Calculation of diffusion polarization voltage]
In the battery internal resistance component estimation method according to the first embodiment, the diffusion polarization voltage ΔV is calculated.
For the diffusion polarization voltage ΔV, in the lithium ion battery as the battery 5, the polarization voltage due to the concentration difference caused by the diffusion of lithium ions is defined as the diffusion polarization voltage ΔV, and the resistance component causing this voltage drop is defined as the polarization resistance. And estimation accuracy is improved by considering this polarization resistance as an internal resistance component of a battery.

First, diffusion will be described.
FIG. 4 is an explanatory diagram of a diffusion state occurring inside the battery.
For example, as shown in FIG. 4, it is assumed that the initial position of the diffusing substance is the concentration calculation position, the initial concentration c _0, and the distance 2L is the limit distance.
As a result, the substance diffuses and moves uniformly over time (see FIGS. 4A to 4C).

FIG. 5 is an explanatory diagram of the diffusion state over time.
Considering the diffusion of the substance with respect to the time axis, expressing the change in concentration at the concentration calculation position in FIG. 4 with respect to time, dividing the concentration value by the initial concentration (division) and setting the initial value to 1, FIG. a), which can be set as a function of f (t).

Here, obtaining diffusion polarization from the diffusion equation and its solution will be described.
If c is the concentration (g / m ³ ), D is the diffusion coefficient (m ² / t), x is the position (m), and t is the time (s), the diffusion equation is as follows.

そして、濃度算出位置Ｌでの近似解は、

The approximate solution at the density calculation position L is

として、

As

(Equation 4)
c = c ₀ (1-exp (−4 × z ² / π)) ^0.5

  It becomes.

  Since the diffusion polarization voltage ΔV is proportional to the concentration,

(Equation 5)
ΔV = ΔVo (1-exp (−4 × z ² / π)) ^0.5

  It becomes.

  Also,

(Equation 6)
f (t) = (1-exp (−4 × z ² / π)) ^0.5

  far.

FIG. 6 is a diagram showing an example of an experimental waveform for determining ΔVo and L / D ^0.5 .
Here, ΔVo is a value determined by the current I after obtaining a waveform in an experiment as shown in FIG. An experiment as shown in FIG. 6 is performed, and L / D ^0.5 is determined by fitting while considering the electrode thickness of the battery with D being 10 ⁻⁸ to 10 ^{−10 in} the measured voltage result and the approximate solution of ΔV. . Alternatively, when L and D can be calculated based on the battery electrode material, electrode thickness, porosity, etc., the values are used.

Next, the case of diffusion in which the concentration decreases by reaction will be described.
FIG. 7 is an explanatory diagram of a state in which the substance concentration decreases with time due to diffusion and reaction.
In FIG. 7, when the reaction takes place at a diffusion distance of 2 L and the diffusing material is consumed, the concentration of the material becomes 0 at that location. Since reaction and diffusion occur simultaneously in the battery 5, it is necessary to correct the solution of the diffusion equation described above.

FIG. 8 is a graph showing the relationship between curves before and after correction. FIG. 9 is an explanatory diagram showing an example of an experimental waveform for determining a correction coefficient.
The solution of the diffusion equation is illustrated as f (t) in FIG. 8. However, as compared with the experimental data in which a constant current flows as shown in FIG. 9, a deviation occurs as the current increases. For this reason, fitting is performed by an experiment as shown in FIG. 9 to calculate the relationship between the correction coefficient and the current. The corrected curve can be calculated by raising f (t) to the power of the correction coefficient. When this curve is multiplied (multiplied) by ΔVo determined from the current I in FIG. 9, it becomes a value closer to the ΔV curve in FIG. 9 than the curve before correction.

FIG. 10 is a graph showing the relationship between the temperature and the temperature coefficient calculated from the Arrhenius law.
Furthermore, assuming that ΔV follows Arrhenius law, when 25 ° C. is used as a reference for the temperature coefficient, the temperature coefficient is expressed by the following equation.

(Equation 7)
Temperature coefficient = exp (-U / kT) / (exp (-U / k x 298))

  When the corrected value of the diffusion coefficient D is D ′,

(Equation 8)
D ′ = D × temperature coefficient

By substituting D ′ calculated from Equation 8 into (Equations 3 to 4), ΔV subjected to temperature correction can be calculated (see FIG. 10). T is the battery temperature (K), U is the activation energy (eV) of the positive electrode material, 1 eV is 1.602 × 10 ⁻¹⁹ (J), and k is 1.380 × 10 ⁻²³ (J / K). Calculate the coefficient.

Next, calculation of the diffusion polarization voltage will be described. The following method is a method that uses an average current because time has elapsed during battery operation and an error has occurred in the open circuit voltage Eo calculated from current integration.
FIG. 11 is a graph showing an example of battery current change measured by a sensor. FIG. 12 is a graph showing the average current calculated from the battery current measured by the sensor.
As shown in FIG. 11, the time until the sign of the sensor current changes is counted. Note that it is also considered that the sign has changed when 0A is reached (step S91).
That is, depending on the load 6 supplied with power, the battery current to be measured repeats the inversion of the sign or repeats 0A and a predetermined value. Here, the average current can be calculated in the power supply state to various loads 6 so as to include the case where the sign change of the current becomes 0A.

  Assuming that the current measurement interval is tc (s) and the time count tx (s) is reset by changing the current sign, the average current Ia (A) can be calculated by the following equation (step S92, see FIG. 12).

なお、時間カウントは、電流の符号が変化したら０にする。
図１３は平均電流とΔＶoの関係を示すグラフ図である。図１４は平均電流と拡散方程式の解から算出した分極電圧を示すグラフ図である。図１５は分極電圧の算出状態を示すグラフ図である。
図１６は平均電流と補正係数の関係の例を示すグラフ図である。
補正係数は、一定電流充電または放電後に電流を０Ａにした場合の電圧変化を測定し、基本曲線f(t)と平均電流を用いて予め算出しておいた値を使用する（図１６参照）。

The time count is set to 0 when the sign of the current changes.
FIG. 13 is a graph showing the relationship between the average current and ΔVo. FIG. 14 is a graph showing the polarization voltage calculated from the average current and the solution of the diffusion equation. FIG. 15 is a graph showing the calculation state of the polarization voltage.
FIG. 16 is a graph showing an example of the relationship between the average current and the correction coefficient.
As the correction coefficient, a voltage change is measured when the current is set to 0 A after constant current charging or discharging, and a value calculated in advance using the basic curve f (t) and the average current is used (see FIG. 16). .

  Next, a method for calculating ΔVa will be described. The relationship as shown in FIG. 13 is calculated in advance, and ΔVo is calculated from the average current at time tx. ΔVo is a saturation polarization voltage. Then, from the curve obtained by correcting the basic curve f (t) calculated from the solution of the diffusion equation and the relationship between FIG. 13 and FIG. 16, ΔVa until immediately before the current sign changes is calculated by the following equation (step S93). FIG. 14, FIG. 15, FIG. 16).

(Equation 10)
ΔVa = ΔVo × {1-f (t)} ^{correction coefficient}

Next, calculation of ΔVb will be described.
FIG. 17 is an explanatory graph of the polarization voltage (ΔVb) calculated from ΔV and the solution of the diffusion equation. FIG. 18 is a graph showing a state in which the polarization voltage (ΔVb) is calculated.
From the curve obtained by correcting the basic curve f (t) calculated from the solution of the diffusion equation, ΔVb until immediately before the current sign changes is calculated by the following equation (see step S94, FIG. 18). Note that f (t) is a basic curve calculated from the solution of the diffusion equation, and the correction coefficient is ΔV, and ΔVo is set to ΔV in the relationship of FIG. 13 to determine the average current, and the relationship between the average current and FIG. It is a value calculated from

(Equation 11)
ΔVb = ΔV × {1-f (t)} ^{correction coefficient}

Next, ΔV between tx is calculated.
FIG. 19 is an explanatory diagram showing a calculation state of the polarization voltage ΔV.

  Using ΔVa and ΔVb, ΔV between tx is calculated by the following equation (step S95).

(Equation 12)
ΔV = ΔVa + ΔVb

  ΔV calculated just before the current sign changes and the time count is reset is used to calculate ΔVb (becomes an initial value of ΔVb). When the current 0A continues, ΔVa = 0, so ΔV can be calculated at a voltage (current) measurement time interval from the change in ΔVb.

[Operation to calculate battery capacity SOC]
FIG. 20 is an explanatory diagram of a battery circuit including an internal resistance. FIG. 21 is an explanatory diagram of current-voltage characteristics.
The DC internal resistance of the battery will be described. In the case of direct current resistance, a current drop IR due to the internal resistance R occurs according to the current I flowing from the battery (see FIG. 21). Eo is an ideal battery voltage when there is no internal resistance in the battery, and can be measured when the circuit current I is zero. This is called an open circuit voltage (open electromotive force) (see FIG. 21).

FIG. 22 is a graph showing the relationship between the battery open voltage and the SOC.
In the case of a lithium ion battery, since there is a relationship between the battery open voltage and the SOC as shown in FIG. 21, the SOC can be known by measuring the open voltage.
When the battery is in operation, since the current flows, it is not easy to directly measure the open circuit voltage with a voltage sensor or the like, but the battery terminal voltage V, current I, internal resistance R and open circuit voltage Eo are shown in FIG. Since there is a relationship shown, an open circuit voltage can be calculated if the internal resistance value can be detected during operation.

FIG. 23 is a diagram of an equivalent circuit of a battery including a polarization resistance. FIG. 24 is a graph showing current-voltage characteristics including polarization resistance.
FIG. 23 shows an example of an internal resistance equivalent circuit when a component other than the DC resistance of the battery is included. In FIG. 23, resistance _RA is the contact resistance due to the connection line of the battery, the resistance when ions pass through the electrolyte, and the resistance when ions pass through the separator-electrode interface (ie, the steady component). Resistance R _B is the resistance due to the speed of the electrode reaction (e.g., Li-ion and e ^- reaction) and, ion or is formed from a resistance due to the diffusion rate of the gas, i.e. a transient component appearing during a transient.

When the voltage drop caused by the polarization resistance and [Delta] V, it becomes current-voltage characteristics as shown in FIG. 24, the resistance DC resistance R _A, if the voltage drop due to polarization resistance of the resistor R _B is known, is possible to calculate the exact Eo it can. This makes it possible to accurately calculate the SOC.

FIG. 25 is an explanatory view showing the state inside the lithium ion secondary battery.
FIG. 25 shows the internal state of the lithium ion secondary battery when the discharge continues. In the case of discharge, the concentration of lithium ions increases in the vicinity of the positive electrode. This is because charging (discharging) continues, the electrode reaction is stabilized, and the diffusion of lithium ions is rate-limiting. The resulting lithium ion concentration gradient appears as a concentration polarization voltage (resistance), which is one of the polarization voltages (resistance).

  FIG. 26 is a graph showing a change state of current and voltage when measuring DC internal resistance. FIG. 27 is an explanatory diagram of the DC internal resistance of the battery and the measurement circuit.

  In a battery having an internal resistance as shown in FIG. 27, when there is a change in current as shown in FIG. 26, the DC internal resistance value can be calculated by the following equation.

図２８はサンプリング時間を考慮した場合の直流内部抵抗測定時の電流と電圧の変化状態を示すグラフ図である。
実際は、電流と電圧、温度の測定において、サンプリング時間間隔でデータが取得されるので、図２８に示すようになる。従って、計算は、次の式のようになるが、直流抵抗Ｒを算出することができる。

FIG. 28 is a graph showing a change state of current and voltage at the time of measuring the DC internal resistance in consideration of the sampling time.
Actually, in the measurement of current, voltage, and temperature, data is acquired at sampling time intervals, as shown in FIG. Therefore, the calculation is as shown in the following equation, but the DC resistance R can be calculated.

図２９に示すのは、図２のステップＳ９で実行される直流抵抗Ｒ部分の算出処理を示すフローチャートで、以下各ステップについて説明する。
なお、このフローチャートでは、実際のデータがサンプリング時間間隔で取得されることを考慮し、電圧センサ３で検出される電圧をＶi、電流センサ４で検出される電流をＩi、温度センサ７で検出される温度をＴiとする。ここで、iは、取得するデータ数とともに増加していく数とする。

FIG. 29 is a flowchart showing the calculation process of the DC resistance R portion executed in step S9 of FIG. 2, and each step will be described below.
In this flowchart, considering that actual data is acquired at sampling time intervals, the voltage detected by the voltage sensor 3 is Vi, the current detected by the current sensor 4 is Ii, and the temperature sensor 7 is detected. Let T i be the temperature to be measured. Here, i is a number that increases with the number of data to be acquired.

  In step S101, n is set to 1, the resistance value R (average) of the internal resistance is the previously measured resistance value R, i is set to 0, I0 is set to 0, and Vo is set to the battery voltage at I0 = 0. .

  In step S102, the calculation of i = i + 1 is performed, and the count-up for inputting the next data is performed.

  In step S103, a conditional expression of | Ii−Ii−1 |> = X (threshold) is calculated. If the condition is satisfied, the process proceeds to step S104. If the condition is not satisfied, the process returns to step S102. In this process, by providing the current change with the threshold value X, the resistance value R is prevented from becoming large when the current change is small, and the resistance value R can be calculated more accurately when the current change is large.

  In step S104, the resistance value R of the internal resistance is calculated by Equation 14.

  In step S105, a conditional expression of R> 0 is calculated. If the condition is satisfied, the process proceeds to step S106, and if the condition is not satisfied, the process returns to step S102. In this process, the process of removing R = 0 and abnormal values, that is, R <0 is performed.

  In step S106, temperature correction is performed by dividing (dividing) the resistance value R of the internal resistance by the temperature coefficient. Since the resistance value R depends on temperature (Arrhenius law), temperature correction is performed and converted to a value under the same temperature (for example, 25 ° C.) condition.

  In step S107, R (average) = (R (average) + R) / n is calculated, and the average value of the resistance values R is calculated. It is also effective to prevent sudden changes by taking a weighted average. Here, as an example, a 1/2 average calculation is shown.

  In step S108, it is determined whether or not the vehicle is stopped. If it is stopped, the process proceeds to step S109, and if it is not stopped, the process returns to step S102. Here, the stop is when the ignition is off or when the passenger gets off. The getting-off is detected by detecting opening / closing of a door, a load of a seat, and the like.

  In step S109, the resistance value R (average) is backed up in the memory as an internal resistance value. The backed up internal resistance value R is used for battery deterioration determination and input / output power calculation.

According to the above processing, the data obtained at the sampling time interval is actually set to the count number i, and the internal resistance value R can be calculated by the processing using Expression 14.
Also, since the internal resistance value R is calculated by removing the abnormal value and taking the weighted average for the resistance value subjected to temperature correction, it becomes a more accurate value, and the battery deterioration determination and input / output power calculation accuracy To increase.

FIG. 30 is a diagram showing an equivalent circuit of a battery having only DC resistance (R, r). FIG. 31 is a diagram showing an equivalent circuit of a battery to which a polarization resistance component is added. FIG. 32 is a time chart showing the difference between the battery equivalent circuit and the voltage change. FIG. 33 is a time chart showing the difference between the battery equivalent circuit and the estimated Eo value.
For example, as the value of the internal resistance used for calculating the charge capacity of the battery, only the DC resistance R and resistance r of an equivalent circuit as shown in FIG. 30 can be considered.

If the internal resistance is only the DC resistance (R, r), the voltage change when the current changes in a step shape is as shown in FIG. However, since the actual voltage changes as shown in FIG. 32C, it can be considered that the influence of a transient polarization component appears (see FIG. 31).
Since the open circuit voltage Eo is calculated from the measurement voltage V measured by the voltage sensor 3 using the internal resistance, considering only the DC resistance, FIG. 33 (a) is obtained. Therefore, considering only the DC resistance, the open circuit voltage Eo necessary for calculating the resetting SOC cannot be accurately calculated, resulting in a large error in the battery capacity meter.
On the other hand, when the open circuit voltage Eo is calculated using the internal resistance in consideration of the polarization resistance component as in the first embodiment, the result is as shown in FIG. 33 (b), which is an error close to Eo in FIG. 32 (c). Can be estimated.

In other words, explain.
Considering an equivalent circuit considering only the DC resistance as shown in FIG. 30, Eo = V-IR-Ir.
However, in practice, since a difference occurs as shown in FIG. 32 (c), a case where a polarization component is considered as shown in FIG. 31 is considered.
Where I (A) is the measured current, V (v) is the measured voltage between terminals, R (Ω) is the internal resistance of the DC component, ΔV (v) is the diffusion polarization voltage, and Eo (v) is the battery open voltage. To do.
In this case, Eo = V−ΔV. Here, ΔV is a function of time t, and when I = 0, ΔV decreases according to a curve given as a solution of the diffusion equation.
That is, if the diffusion polarization voltage can be calculated, the estimation accuracy of the battery open voltage Eo is improved.

In the first embodiment, the diffusion polarization voltage ΔVa at which diffusion polarization progresses by diffusion over time using a solution of a diffusion equation that has been fitted to be used for estimation by experiments or the like and improved in accuracy, and over time. The diffusion polarization voltage Vb generated when the diffusing substance is eliminated by the reaction of the diffusing substance is calculated. Then, the diffusion polarization voltage ΔV due to the diffusion polarization resistance is calculated together.
Since the direct current component (R) can be obtained with high accuracy according to FIGS. 26, 27, and 12, the internal resistance of the battery can be estimated with high accuracy.

FIG. 34 is a time chart showing characteristics in which diffusion polarization is eliminated.
In the first embodiment, even when the battery voltage slowly changes due to the influence of the polarization voltage as shown in FIG. 34, the calculation system of the open circuit voltage Eo is improved by taking the polarization voltage into account, and the battery charge capacity is accurately determined. Can be calculated well.

Next, the effect will be described.
In the battery internal resistance component estimation method according to the first embodiment, the effects listed below can be obtained.

  (1) A method for estimating an internal resistance component of a battery 5 composed of a plurality of unit battery cells, in which a voltage caused by uneven distribution due to diffusion movement of an ionic substance inside the battery 5 is taken into account for the internal resistance component of the battery 5 Since the diffusion polarization resistance is set and the diffusion polarization resistance is estimated using the time variation of the concentration of the diffused material, the accuracy of the internal resistance estimation value can be improved, and the calculation accuracy of the battery capacity SOC is improved. it can.

  (2) In the above (1), in order to estimate the change over time of the concentration of the diffusing material using the diffusion equation, the change over time in the concentration of ions moving for the electrode reaction that generates a voltage inside the battery is determined using the diffusion equation. Since the voltage difference caused by diffusion polarization is accurately estimated, the accuracy of the internal resistance estimated value can be improved, and the calculation accuracy of the SOC that is the battery capacity can be improved.

  (3) In the above (1) or (2), the internal resistance component of the battery 5 is set to the diffusion polarization resistance and the DC internal resistance that causes a voltage drop in series. In order to estimate the resistance component, the contact resistance due to the connection line of the battery 5, the resistance when ions pass through the electrolytic solution-contacted electrolytic solution, the resistance when ions pass through the separator-electrode interface, in accordance with the DC internal resistance And the resistance due to the diffusion rate of ions or gas can be taken into account by the diffusion polarization resistance, so that the accuracy of the internal resistance estimation value can be improved. Can be improved.

(4) In the above (1) to (3), the diffusion polarization resistance detects the current value supplied by the battery 5 and divides it into a plurality of time intervals tx by the change in sign of the detected current, and averages each time interval tx calculates the current Ia, calculates the saturation polarization voltage delta Vo of the average current Ia from a previously determined relationship, using the curve f (t) calculated from the solution of the diffusion equation, is positive or negative high potential with time the progress change of diffusion polarization towards and saturated polarization voltage delta Vo in direction, is calculated as a diffusion polarization voltage ΔVa just before the sign of the detected current changes time interval tx, for the estimation, diffusion polarization voltage in progress Can be accurately estimated to improve the accuracy of the internal resistance estimation value, and as a result, the calculation accuracy of the battery capacity SOC can be improved.

  (5) In the above (4), the diffusion polarization resistance is calculated by calculating ΔV from the diffusion polarization voltage ΔVa of the previous time interval and the diffusion polarization voltage ΔVb of the previous time interval, and the ΔV and the diffusion equation at the next time interval. Using the curve f (t) calculated from the above solution, the diffusion polarization elimination change in the direction in which the potential difference decreases with the passage of time is defined as the diffusion polarization voltage ΔVb until just before the sign of the detected current changes for each time interval. Calculate and estimate the diffusion polarization voltage ΔV by adding the diffusion polarization voltage ΔVa and the diffusion polarization voltage ΔVb until just before the sign of the detected current changes at the same time interval, so the diffusion polarization is eliminated by the electrode reaction It is possible to accurately estimate the phenomenon to be performed, improve the accuracy of the internal resistance estimation value, and thus improve the calculation accuracy of the SOC that is the battery capacity.

  (6) In the above (4) or (5), a voltage change is measured when the detected current value is set to 0 A after charging or discharging the predetermined current detected, and the curve f (t) As the current value (voltage value) increases, the amount of elimination of diffusion caused by the reaction increases and the actual value deviates from the curve f (t). The correction will be made in consideration of the phenomenon, and the accuracy of the estimation using the curve f (t) can be improved, so that the accuracy of the internal resistance estimation value can be improved. Can be improved.

  (8) When the battery is not operating, the open circuit voltage Eo is measured. When the battery is operating, the open circuit voltage Eo is estimated and calculated from the internal resistance component estimated by the above (1) to (6) and the detected current. Since the charge capacity of the battery is calculated from the open-circuit voltage Eo regardless of the operating state based on the relationship obtained in advance, the calculation accuracy of the SOC, which is the battery capacity, can be improved by the estimated internal resistance value. Further, for example, even when the battery voltage changes slowly due to the influence of the polarization voltage, the calculation accuracy of the open circuit voltage Eo can be improved and the SOC can be accurately calculated by considering the polarization voltage.

Example 2 is an example in which the time count tx (s) is set to a period during which the sensor current change is smaller than the specified value when calculating the diffusion polarization voltage.
Since the configuration is the same as that of the first embodiment, the description thereof is omitted.
The operation will be described.

[Calculation of diffusion polarization voltage]
In the second embodiment, the time elapses during the battery operation, and an error occurs in the open circuit voltage Eo calculated from the current integration, and the average current is used.
FIG. 35 is a graph showing an example of battery current change measured by the sensor in Example 2. FIG. 36 is a graph showing the average current calculated from the battery current measured by the sensor in Example 2.
In Example 2, the time during which the sensor current change is smaller than the specified value is counted. In FIG. 35, the specified value is 10A as an example.
Then, the average current Ia (A) can be calculated from the counted time count tx (s) and Equation 9 (see FIG. 36).

The time count tx (s) is counted again from the beginning (1 × tc) when the change in current exceeds a specified value. The current at the start of counting is I1, and the current measurement interval is tc.
FIG. 37 is a graph showing the relationship between the average current and time in Example 2. FIG. 37 (b) is a partially enlarged explanatory view of FIG. 37 (a). FIG. 38 is a graph showing the state of calculation of the polarization voltage in Example 2. FIG. 39 is a graph showing a state in which the calculated polarization voltage is calculated from the average current and the solution of the diffusion equation in Example 2.
The relationship between the calculated average current Ia (A) and time can be expressed as shown in FIG. 37B from the measurement interval tc, where time t_n.

Next, an average current and ΔVo relationship as shown in FIG. 13 (similar to the first embodiment) is calculated in advance, and ΔVo_n is calculated from the average current Ia_n at time t_n.
Then, from the relationship between the curve obtained by correcting the basic curve f (t) calculated from the solution of the diffusion equation and FIG. 13 (similar to Example 1), ΔVa until the current change exceeds the specified value is expressed by the following equation: Calculate (see FIGS. 38 and 39).

(Equation 15)
ΔVa_n = ΔVo_n × {1-f (t)} ^{correction coefficient}
As the correction coefficient, a voltage change is measured when the current is set to 0 A after charging or discharging at a constant current, and a value calculated in advance using the basic curve f (t) and the average current is used (in Example 1). (Since it is the same as FIG. 16, illustration is omitted).

Next, calculation of ΔVb_n will be described.
FIG. 40 is an explanatory graph of the polarization voltage (ΔVb) calculated from ΔV and the solution of the diffusion equation in Example 2. FIG. 41 is a graph showing a state in which the polarization voltage (ΔVb_n) in Example 2 is calculated. 41 is an enlarged view of a portion A1 in FIG.
From the curve obtained by correcting the basic curve f (t) calculated from the solution of the diffusion equation, ΔVb_n until the change in current exceeds the specified value is calculated by the following equation (see FIG. 41). Note that f (t) is a basic curve calculated from the solution of the diffusion equation, and the correction coefficient is ΔV_n calculated below, and ΔVo_n is set to ΔV_n in the relationship of FIG. It is a value determined and calculated from the relationship between the average current and FIG. 13 (similar to Example 1).

(Equation 16)
ΔVb_n = ΔV_n × f (t) ^{correction coefficient}

Next, ΔV_n at time tn is calculated.
FIG. 42 is an explanatory diagram illustrating a calculation state of the voltage ΔV by polarization in the second embodiment. FIG. 43 is an explanatory diagram illustrating a calculation state of the polarization voltage ΔV_n in the second embodiment. 42 is the same as FIG. 39, and the enlarged view of the A3 portion in FIG. 42 is FIG.
Between time t_n, ΔV_n at tn is calculated by the following equation using ΔVa_n and ΔVb_n calculated.

(Equation 17)
ΔV_n = ΔVa_n + ΔVb_n
As shown in FIG. 43, the polarization voltage ΔV_n is calculated from ΔVa_n and ΔVb_n in consideration of the diffusion equation, as indicated by ΔV_1 to ΔV_4.
ΔV_n calculated immediately before the time count is reset is used to calculate ΔVb_n (becomes an initial value of ΔVb_n). Further, when the current continues at 0 A, ΔV_n can be calculated at a voltage (current) measurement time interval from the change in ΔVb_n (because ΔVa_n = 0).

Explain the effect. The battery internal resistance component estimation method according to the second embodiment has the following effects in addition to the above (1) to (6) and (8).
(7) For the time interval tx for calculating the average current Ia, the current value supplied by the battery 5 is detected and divided into a plurality by the sign change of the detected current, and the current change amount at the same sign is smaller than the specified value Since it is divided into a plurality of periods, the average current Ia is calculated as the average of a plurality of data with little fluctuation, and the accuracy is improved by making the average current Ia accurate so that no deviation from the data occurs. As a result, the accuracy of the estimated internal resistance can be improved, and as a result, the calculation accuracy of the SOC that is the battery capacity can be improved.
Since other functions and effects are the same as those of the first embodiment, description thereof is omitted.

The third embodiment is an example in which the DOD that is the discharge capacity is calculated by the battery internal resistance component estimation method, and the usable time is calculated.
The configuration will be described.
FIG. 44 is a block diagram illustrating a configuration of a battery device using the battery internal resistance component estimation method and the discharge capacity estimation method according to the third embodiment.
The battery device 1 according to the third embodiment includes a battery controller 2, a voltage sensor 3, a current sensor 4, a battery 5, a load 6, a temperature sensor 7, an output limiting device 8, and a usable time display device 9.

The output limiting device 8 is a relay or the like that stops the output so that the power supply from the battery 5 to the load 6 is not supplied below the discharge stop voltage. Note that the discharge stop voltage is set in advance as a voltage that does not hinder the performance of the battery 5 that repeats charging and discharging.
The usable time display device 9 displays the remaining usable time in time when the battery 5 is in a use state in which the battery 5 is continuously discharged. The usable time display device 9 may be a part of another display device or may be provided as a function of the other display device.

FIG. 45 is a block diagram illustrating a control configuration for executing the internal resistance component estimation method and the discharge capacity estimation method of the battery according to the third embodiment.
The block configuration of FIG. 45 is configured as a program or a circuit inside the battery controller 2.
This block configuration includes a DC resistance calculation unit 21, a diffusion polarization voltage calculation unit 22, a battery capacity calculation voltage calculation unit 23, and a usable time calculation unit 24.
45, the battery voltage V detected by the voltage sensor 3, the current value I detected by the current sensor 4, and the battery temperature T detected by the temperature sensor 7 are input.

The direct current resistance calculation unit 21 calculates the direct current resistance R portion from the battery voltage V, the current value I, and the battery temperature T, and outputs it to the battery capacity calculation voltage calculation unit 23.
Diffusion polarization voltage calculation unit 22 calculates diffusion polarization voltage ΔV from current value I and battery temperature T, and outputs it to battery capacity calculation voltage calculation unit 23.
The battery capacity calculation voltage calculation unit 23 calculates the battery capacity calculation voltage Vc from the DC resistance R, the battery voltage V, the current value I, and the diffusion polarization voltage ΔV, and outputs it to the usable time calculation unit 24.
The usable time calculation unit 24 calculates the usable time from the battery capacity calculation voltage Vc and outputs it to the usable time display device 9.
Since other configurations are the same as those of the first embodiment, description thereof is omitted.

The operation will be described.
[Battery usage time calculation process]
FIG. 46 is a flowchart showing the flow of the usable time calculation process executed by the battery controller 2 of the third embodiment. Each step will be described below.

  In step S31, the battery controller 2 inputs the battery voltage V detected by the voltage sensor 3, the current value I detected by the current sensor 4, and the battery temperature T detected by the temperature sensor 7, and calculates SOC (%). The calculation of SOC is the same as in the first and second embodiments.

  In step S32, the DC resistance calculator 21 calculates the DC resistance R. The content of the calculation process is the same as in the first embodiment. Then, the correction value of the DC resistance R is R ′, and the temperature correction is performed to a resistance value corresponding to 25 ° C. from R ′ = R × temperature coefficient. Further, the correction value R ′ is set to R ″, and correction is performed so that it corresponds to 0% of SOC by R ″ = R ′ × capacitance coefficient.

  In step S33, the diffusion polarization voltage calculator 22 calculates a voltage ΔV that is a polarization resistance voltage drop. The processing content of the voltage drop ΔV due to the polarization resistance is the same as in the first embodiment. Then, the correction value of the diffusion coefficient D is set to D ′, and the temperature correction corresponding to 25 ° C. is performed by the correction value ΔV ′ of the voltage drop ΔV calculated from D ′ = D × temperature coefficient (corresponding to 25 ° C.). Further, the correction value ΔV ′ is set to ΔV ″, and correction is performed so as to be equivalent to 0% of SOC by ΔV ″ = ΔV ′ × capacitance coefficient.

  In step S34, the battery capacity calculation voltage calculation unit 23 calculates the battery capacity calculation voltage Vc (V) by the battery capacity calculation voltage Vc = discharge stop voltage−I × R ″ −ΔV ″.

  In step S35, the usable time calculation unit 24 calculates DOD_VC, which is a DOD at the voltage Vc, from the open circuit voltage Eo curve.

  In step S36, the usable time calculation unit 24 sets CF (Ah) as the full capacity (Ah) of the battery 5 that is the Ah capacity of the battery 5 when the DOD is 0%, and the dischargeable full capacity (Ah) = CF × The dischargeable full capacity is calculated by DOD_VC / 100.

In step S <b> 37, the usable time calculation unit 24 calculates a dischargeable capacity according to dischargeable capacity (Ah) = dischargeable full capacity × SOC / 100.
The description so far is when the deterioration of the battery is ignored, and the discharge capacity (Ah) at DOD 100% = full capacity (Ah). Actually, the full capacity (Ah) decreases due to the battery usage period, storage at high temperature, and charge / discharge cycles, but this is done by conducting charge / discharge tests on batteries that have deteriorated separately and have reduced capacity, and the full capacity defined by DOD 100%. By measuring the capacity and updating the value of the full capacity according to the deterioration state of the battery, the dischargeable full capacity can be similarly calculated.

  In step S <b> 38, the usable time calculation unit 24 calculates the usable time based on the usable time (h) = dischargeable capacity (Ah) / I (A).

  In step S39, it is determined whether or not the usable time calculation process is to be terminated. If it is to be terminated, the process is terminated. If not, the process returns to step S31. For example, it may be completed by switching the charge / discharge state of the battery, stopping the use of the vehicle, or the like.

[DOD and usable time calculation]
FIG. 47 is an explanatory diagram showing a calculation state of the battery capacity calculation voltage Vc in the third embodiment. FIG. 48 is an explanatory diagram showing a calculation state of the usable battery full capacity in the third embodiment.
Since the calculation of the direct current resistance R and the polarization resistance voltage ΔV is the same as in the first and second embodiments, the description thereof is omitted. In the third embodiment, similarly to FIG. 10 of the first embodiment, the temperature correction based on the temperature coefficient calculated from the Arrhenius rule and the correction equivalent to SOC 0% are performed (steps S32 and S33).

Then, through the process of step S34, the battery capacity calculation voltage calculation unit 23 calculates the battery capacity calculation voltage Vc (V).
Here, with reference to FIG. 47, the battery capacity calculation voltage Vc takes a value between the full charge voltage and the discharge stop voltage, and the value is the discharge stop voltage −I × R ″ −. Calculated by ΔV ″. (Here again, ΔV <0 if I <0.)

And calculation of the usable battery full capacity of step S35 which the usable time calculation part 24 performs is demonstrated with reference to FIG. When DOD is taken on the horizontal axis, the open-circuit voltage Eo curve from the full charge voltage to the discharge stop voltage is as shown in FIG. From this characteristic curve and the battery capacity calculation voltage Vc obtained in the process of step S34, DOD_VC that is the usable battery full capacity is obtained.
As shown in FIG. 48, when DOD_VC of DOD (discharge capacity) of the discharge stop voltage, that is, DOD = 100%, is subtracted from DOD_VC, ΔSOC is indicated. Note that the relationship between the open-circuit voltage Eo and the SOC shown in FIG. 48, which is obtained and set in advance by experiments or the like by performing temperature correction and capacity correction on the resistance value R ″ and the voltage ΔV ″, can be used.

From the DOD_VC obtained in this way, the dischargeable full capacity and the dischargeable capacity are calculated. Since the dischargeable capacity is Ah, the usable time is calculated by dividing by the current value I (A).
As described above, in the third embodiment, by accurately obtaining the estimated internal resistance value by the diffusion polarization resistance, the accuracy of the usable DOD (DOD_VC) is improved, and the usable time is calculated and displayed with high accuracy.

Further explanation will be given.
49 is a graph showing a discharge curve at 20 ° C. in Example 3. FIG. 50 is a graph showing a discharge curve at 0 ° C. in Example 3. FIG.
The battery 5 at 20 ° C. discharges in a curve as shown in FIG. Here, FIG. 49 shows discharge curves when the battery current value I is 0.2 C (360 mA), 1.0 C (1800 mA), and 2.0 C (3600 mA). It can be seen that the discharge capacity decreases as the current of the battery 5 increases. FIG. 50 shows a discharge curve of the battery 5 at 0 ° C. It can be seen that when the temperature of the battery 5 decreases, the discharge capacity also decreases. This is because the terminal voltage of the battery drops due to the influence of the direct current resistance and polarization resistance of the battery 5 and reaches the discharge stop voltage earlier.

  In Example 3, since the influence of the direct current resistance and polarization resistance can be taken into consideration, the discharge capacity at current and temperature is accurately calculated, and the usable time of the battery 5 is accurately calculated.

In order to clarify the operation of the third embodiment, further explanation will be added below.
FIG. 51 is an explanatory diagram showing a circuit in which the internal resistance is only a DC resistance. FIG. 52 is a graph showing a discharge curve when only the direct current resistance is considered as the internal resistance. FIG. 52 shows discharge curves when the current values are 0.2 C (360 mA), 0.5 C (900 mA), 1.0 C (1800 mA), and 2.0 C (3600 mA).

  When estimating a discharge curve in consideration of internal resistance, it is conceivable to consider DC resistance as internal resistance as shown in FIG. As shown in FIG. 51, when the internal resistance is only a DC resistance, even if the current changes, the change in the discharge capacity is small. Therefore, as the current flowing increases, the usable time is displayed as the end of discharge is approached. An error will occur. For this reason, the user cannot accurately grasp the usable time of the device driven by the battery 5.

FIG. 53 is an explanatory diagram showing a circuit set in the third embodiment in which the internal resistance includes a DC resistance and a polarization resistance. FIG. 54 is a graph of a discharge curve in Example 3 in which the internal resistance includes polarization resistance.
As shown in FIG. 53, in Example 3, since the internal resistance considers the DC resistance and polarization resistance, the discharge curve is as shown in FIG. In the discharge curve of FIG. 54, when the current changes, the influence of polarization resistance appears, and even when the current increases, the discharge capacity can be calculated more accurately. For this reason, the user accurately grasps the usable time of the device driven by the battery 5.

Further explanation will be added.
For the battery status display, the charge capacity (SOC), the number of charge / discharge cycles, the usable time, etc. can be considered. Since the battery 5 has a reduced energy that can be taken out due to deterioration or a decrease in battery temperature, the discharge time varies depending on the use situation even when the same output is obtained.
That is, since the internal state of the battery 5 changes depending on the current usage situation and how it was used, it is difficult to calculate the usable battery capacity. However, for example, when it is used for driving a vehicle or when there is an importance such as an air conditioner used in a cabin temperature environment that affects the evaluation of the vehicle, a more accurate display of the usable time is required. In the third embodiment, the usable time with high accuracy is provided by considering the influence of the polarization resistance.

Explain the effect. Example 3 has the following effects in addition to the above (1) to (7).
(9) Discharge stop set in advance as a limit of the discharge capacity from the product of the voltage drop ΔV due to the internal resistance component estimated by the above (1) to (7), the detection current I and the DC component R, and the full charge voltage Based on the discharge characteristics up to the voltage, the usable dischargeable capacity DOD_VC up to the discharge stop voltage is estimated, and the battery use when the current battery use state continues from the detected current I and the dischargeable capacity DOD_VC Since the possible time is estimated and calculated, the calculation accuracy of the battery usage time can be improved by the estimated internal resistance value accurately estimated.

As mentioned above, although the internal resistance component estimation method of the battery according to the present invention has been described based on the first embodiment, the specific configuration is not limited to these embodiments, and each claim of the claims Design changes and additions are allowed without departing from the gist of the invention.
In Example 1, since the value to be actually estimated is Eo, the voltage drop ΔV due to the diffusion polarization resistance component is obtained. However, depending on the method of use, the diffusion polarization resistance may be obtained.
The battery includes a case where a primary battery, a secondary battery, and a single battery are combined in series or in parallel.

DESCRIPTION OF SYMBOLS 1 Battery apparatus 2 Battery controller 3 Voltage sensor 4 Current sensor 5 Battery 6 Load 7 Temperature sensor 8 Output limiting device 9 Usable time display apparatus

Claims (7)

A battery internal resistance component estimation method comprising a plurality of unit battery cells,
In the internal resistance component of the battery, set a diffusion polarization resistance in consideration of the voltage generated by uneven distribution due to the diffusion movement of the ionic substance inside the battery,
In the battery internal resistance component estimation method for estimating the diffusion polarization resistance by using the time variation of the concentration of the diffusion material,
The diffusion polarization resistor detects a current value supplied by the battery, divides into a plurality of time intervals by a change in sign of the detected current, calculates an average current Ia in each time interval, and calculates the average current from a previously obtained relationship. The saturation polarization voltage ΔVo of Ia is calculated, and using the curve f (t) calculated from the solution of the diffusion equation, the progress of diffusion polarization toward the saturation polarization voltage ΔVo in the direction in which the potential difference is positive or negative is increased with time. The change is calculated as a diffusion polarization voltage ΔVa until immediately before the sign of the detection current changes for each time interval, and estimation is performed.
The internal resistance component estimation method of the battery characterized by the above-mentioned. The battery internal resistance component estimation method according to claim 1,
In the internal resistance component of the battery, set the DC internal resistance that causes a voltage drop in series with the diffusion polarization resistance,
Estimating the internal resistance component from the change in detected current and the voltage between terminals,
The internal resistance component estimation method of the battery characterized by the above-mentioned. In the battery internal resistance component estimation method according to claim 1 or 2,
The diffusion polarization resistance is such that the diffusion polarization voltage ΔV of the previous time interval decreases in the potential difference with time using the curve f (t) calculated from the solution of the diffusion equation at the next time interval. The change in elimination of diffusion polarization is calculated as a diffusion polarization voltage ΔVb until immediately before the sign of the detection current changes for each time interval, and the diffusion polarization voltage until just before the sign of the detection current changes in the same time interval The diffusion polarization voltage ΔV is calculated by adding ΔVa and the diffusion polarization voltage ΔVb, and estimation is performed.
The internal resistance component estimation method of the battery characterized by the above-mentioned. In the battery internal resistance component estimation method according to any one of claims 1 to 3,
After charging or discharging the detected current of a predetermined value, the voltage change when the detected current value is set to 0A is measured, a correction coefficient for correcting the curve f (t) is obtained, and the curve f (t) Correct the
The internal resistance component estimation method of the battery characterized by the above-mentioned. In the internal resistance component estimation method of the battery according to any one of claims 1 to 4,
The time interval for calculating the average current Ia is not limited to detecting the current value supplied by the battery and dividing it into a plurality by the sign change of the detected current. Separate ,
The internal resistance component estimation method of the battery characterized by the above-mentioned. A battery charge capacity estimation method using the battery internal resistance component estimation method according to any one of claims 1 to 4,
When the battery is not operating, the open circuit voltage Eo is measured,
When the battery is in an operating state, the open-circuit voltage Eo is estimated and calculated from the internal resistance component estimated by the internal resistance component estimation method of the battery and the detected current,
The charge capacity of the battery is calculated from the open circuit voltage Eo regardless of the operating state according to the relationship obtained in advance.
A method for estimating the charge capacity of a battery. A battery usable time estimation method using the internal resistance component estimation method for a battery according to any one of claims 1 to 5,
The internal resistance component estimated by the internal resistance component estimation method of the battery, the detected current,
Discharge characteristics from full charge voltage to discharge stop voltage set in advance as the limit of discharge capacity,
Based on the above, a usable dischargeable capacity up to the discharge stop voltage is estimated and calculated,
From the detected current and the dischargeable capacity, a battery usable time is estimated and calculated when the current battery usage state continues.
A method for estimating a usable time of a battery.

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