JP2019020174A - Secondary battery controller - Google Patents

Abstract

To solve the problem that the computation of SOCv contains an error due to a deviation of the equivalent circuit model of a secondary battery itself from actual measurement, etc. caused by deterioration or the like.SOLUTION: A secondary battery controller 102 finds a first open-circuit voltage OCV of a secondary battery 100 from an equivalent circuit that includes at least a polarization component represented by a parallel connection between polarization resistance and capacitive component and an internal resistance component R of the secondary battery 100, and finds a state of charge SOCv of the secondary battery 100 from a relationship between the first open-circuit voltage OCV and the state of charge of the secondary battery 100. Then, the secondary battery controller 102 computes a value subtracting, from the value of measured voltage of the secondary battery 100, the value of a second open-circuit voltage computed by a method different from the first open-circuit voltage OCV, a voltage value Vp of the polarization component computed in accordance with the current information of the secondary battery 100 and a value RI represented by the product of the internal resistance value R and the current value I of the secondary battery 100.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a secondary battery control device.

  In recent years, attention has been focused on storage batteries that can effectively use energy in order to cope with the global warming problem. In particular, since battery systems such as power storage devices for mobile bodies and power storage devices for grid connection stabilization can reduce the dependence on fossil fuels, further spread is expected. In order to bring out the performance of these systems, parameters such as the charging rate of the secondary battery (State of Charge, hereinafter referred to as SOC), the degree of deterioration (State of Health, hereinafter referred to as SOH), and the maximum current (allowable current) that can be charged and discharged It is necessary to appropriately perform charge / discharge control using a battery and equalize the charging rate of each battery. For this purpose, it is desirable that there is little error in the SOC (hereinafter abbreviated as SOCv) calculated based on the open circuit voltage (hereinafter abbreviated as OCV) estimated from the voltage during charging and discharging of the secondary battery. .

  Patent Document 1 describes an apparatus for determining an SOCv calculation error. In this apparatus, the SOCv is calculated using an equivalent circuit model of a battery expressed by a series connection of an OCV, an internal resistance, and a parallel connection pair of a polarization resistance and a capacitance component. At this time, when the capacitance component is saturated, it is determined that the error in the calculation of the SOCv is large.

JP 2006-099156 A

  Since Patent Document 1 captures only a state in which the capacitance component is saturated, that is, a condition in which an error due to the equivalent circuit model of the secondary battery is likely to occur, for example, an actual measurement of the equivalent circuit model of the secondary battery due to deterioration or the like. It was not possible to grasp the error due to the difference in the measurement timing of the current and voltage used in the calculation.

A secondary battery control device according to the present invention includes a first open circuit of the secondary battery from an equivalent circuit having at least a polarization component represented by a parallel connection of a polarization resistance and a capacity component, and an internal resistance component R of the secondary battery. A secondary battery control device for obtaining a circuit voltage OCV and obtaining a charge rate SOCv of the secondary battery from a relationship between the first open circuit voltage OCV and a charge rate of the secondary battery, wherein the secondary battery The control device calculates from the measured voltage value of the secondary battery according to the second open circuit voltage value calculated by a method different from the first open circuit voltage OCV and the current information of the secondary battery. The value obtained by subtracting the voltage value Vp of the polarization component and the value RI represented by the product of the internal resistance component R and the current value I of the secondary battery is calculated.
A secondary battery control device according to the present invention includes a first open circuit of the secondary battery from an equivalent circuit having at least a polarization component represented by a parallel connection of a polarization resistance and a capacity component, and an internal resistance component of the secondary battery. An SOCv calculation unit that obtains a voltage and obtains a charge rate SOCv of the secondary battery from a correspondence relationship between the first open circuit voltage and the charge rate SOC of the secondary battery, and a second different from the first open circuit voltage The battery voltage is calculated based on the open circuit voltage, the voltage value of the polarization component calculated according to the current information of the secondary battery, and the value represented by the product of the internal resistance component and the current value of the secondary battery. A battery voltage estimator for estimation; and an error calculator for calculating an error between the battery voltage estimated by the battery voltage estimator and the measured voltage of the secondary battery.

  According to the present invention, it is possible to calculate an SOCv calculation error.

It is a figure which shows the structure of a battery system. It is a figure which shows the equivalent circuit model of a secondary battery. It is a figure which shows the structure of a SOH calculating part. (A), (b) It is a figure which shows transition of the actual voltage and model estimation voltage, and the difference of both. (A), (b) It is a figure which shows the relationship of the error (alpha) and SOCv calculation error. It is a figure which shows transition of Qmax '. It is a figure which shows an OCV approximation curve. It is a figure which shows the structure of the SOH calculating part by 2nd Embodiment. It is a figure which shows the structure of the 2nd SOC calculating part by 3rd Embodiment.

-First embodiment-
Hereinafter, the first embodiment will be described with reference to FIGS. FIG. 1 is a diagram illustrating a configuration of a battery system. The configuration shown in FIG. 1 is a form used in a wide range of applications such as a power storage device for a mobile body and a power storage device for grid connection stabilization, and a battery system 1 that stores electric power and an inverter that charges and discharges the battery system 1 104, a load 105 connected to the inverter 104, and a host controller 103 that controls the battery system 1 and the inverter 104.

  The battery system 1 stores the power storage and discharge of the secondary battery 100, the charge rate SOC which is a control value necessary for these, and the deterioration degree SOH which is a control value necessary for grasping the current performance of the secondary battery 100. Perform the operation. The host controller 103 controls the secondary battery 100 and issues an input / output command of power to the inverter 104 according to the state of the load 105, the control value of the secondary battery 100 output from the battery system 1, and other external commands. . The inverter 104 inputs and outputs power to the secondary battery 100 and the load 105 in accordance with a command from the host controller 103. The load 105 is, for example, a three-phase AC motor or a power system.

  The voltage output from the secondary battery 100 is a DC voltage that changes in accordance with the charging rate SOC, and in many cases, power cannot be directly provided to the load 105 that requires AC. Therefore, the inverter 104 performs conversion from DC to AC and voltage conversion as necessary. With such a configuration, the battery system 1 can appropriately supply an output suitable for the load. Hereinafter, the configuration of the battery system 1 for realizing this configuration will be described.

  The battery system 1 includes a secondary battery 100, a battery information acquisition unit 101, and a secondary battery control device 102. The battery system 1 stores and discharges electric power, and calculates control values of the secondary battery 100 such as SOC and allowable current. To do.

The secondary battery 100 is composed of a plurality of battery cells. Each battery cell is connected in series or in parallel according to the output voltage and capacity required for the secondary battery 100.
The battery information acquisition unit 101 includes a current sensor 106 that measures the value of current flowing through the secondary battery 100, a temperature sensor 107 that measures the surface temperature of the secondary battery 100, and a voltage sensor 108 that measures the voltage of the secondary battery 100. .

  One or a plurality of current sensors 106 may be installed between the secondary battery 100 and the outside. If one is installed, the cost can be minimized. When a plurality of batteries are installed, it is possible to grasp the current distribution between the battery cells connected in parallel.

  One or a plurality of temperature sensors 107 are installed to grasp the temperature of the secondary battery 100. When one is installed, the temperature at a point where the maximum temperature in the secondary battery 100 can be predicted can be measured at a minimum cost. When a plurality of batteries are installed, it is possible to perform control in consideration of the minimum temperature and the maximum temperature by measuring the temperature variation of the battery cells.

  One voltage sensor 108 is installed in each battery cell. As a result, the voltage difference between the battery cells can be measured, and the voltage equalization control of each battery cell can be performed based on this measurement. The battery information I, T, V measured by the current sensor 106, the temperature sensor 107, and the voltage sensor 108 is input to the secondary battery control device 102.

  The secondary battery control apparatus 102 includes an SOC calculation unit 109, an SOH calculation unit 110, and an allowable current calculation unit 111. The SOC calculation unit 109 includes an SOCi calculation unit 112 that calculates SOCi from the current integration amount, and an SOCv calculation unit 113 that calculates SOCv based on the OCV estimated from the battery information. SOCi and SOCv will be described later.

  The SOH calculation unit 110 includes a SOHQ calculation unit 115 that calculates SOHQ that is a capacity deterioration rate. Moreover, the structure which has the SOHR calculating part which calculates SOHR which is a deterioration rate of resistance based on the battery information from the battery information acquisition part 101 and charging rate SOC may be sufficient.

  The allowable current calculation unit 111 calculates an allowable current Ilimit that is the maximum current that can be charged and discharged based on the SOH from the SOH calculation unit 110 and the battery information from the battery information acquisition unit 101.

  The secondary battery control device 102 outputs the SOC, SOH, and allowable current Ilimit calculated by the SOC calculation unit 109, the SOH calculation unit 110, and the allowable current calculation unit 111 to the host controller 103, respectively. The host controller 103 sends a power output command corresponding to the load 105 to the secondary battery control device 102 in consideration of the state of the secondary battery 100.

[Operation of SOC Calculation Unit 109]
The SOC calculation unit 109 calculates the SOC by the following expression (1) based on the SOCi obtained by the SOCi calculation unit 112 and the SOCv obtained by the SOCv calculation unit 113. In this calculation, a weighting coefficient W for weighting and adding SOCi and SOCv is used. In general, the weighting factor W is weighted so that when the absolute value of the current I is small, SOC is mainly used to calculate the SOC, and when the absolute value of the current I is large, SOCi is mainly used to calculate the SOC. A coefficient W is set. Further, when the internal resistance R of the secondary battery 100 is small, the SOC is mainly used to calculate the SOC, and when the internal resistance R is large, the weight coefficient W is set so that the SOC is mainly calculated using the SOCi. To do.
SOC = W × SOCi + (1−W) × SOCv (1)
Here, the weight coefficient W is a value between 0 and 1.

[Operation of SOCi Operation Unit 112]
The operation of the SOCi calculation unit 112 will be described. The SOCi calculation unit 112 calculates the SOCi of the secondary battery 100 by accumulating the current I charged / discharged by the secondary battery 100 according to the following equation (2). In Expression (2), Qmax is the full charge capacity of the secondary battery 100, and is stored in advance in a storage unit (not shown). SOCold is the SOC value calculated by the equation (1) in the previous calculation cycle.
SOCi = SOCold + 100 × ∫I / Qmax (2)

[Operation of SOCv Operation Unit 113]
Next, the operation of the SOCv calculation unit 113 will be described with reference to FIG. The SOCv calculation unit 113 calculates the SOCv using the equivalent circuit of the secondary battery 100. FIG. 2 shows an equivalent circuit model of the secondary battery 100 used for the calculation. In this equivalent circuit model, the open circuit voltage OCV is expressed by the voltage source 200, and the direct current resistance expressing the resistance of the electrolytic solution and the like is expressed by the resistor 201 (internal resistance R of the secondary battery). Furthermore, the polarization component represented by the parallel connection of the polarization resistance and the capacitance component is composed of a resistance 202 that is a polarization resistance component derived from concentration polarization of ions in the electrolytic solution and a capacitor 203 that is a capacitance component of polarization. expressing. The current voltage (Closed) of the secondary battery 100 is obtained by adding the open circuit voltage OCV of the secondary battery 100, the voltage V ₀ due to the internal resistance of the secondary battery 100, and the voltage (hereinafter referred to as polarization voltage) Vp due to the polarization component. circuit voltage (hereinafter abbreviated as CCV). In the present embodiment, an example in which the polarization term composed of the resistor 202 and the capacitor 203 is one is shown. However, it is possible to increase the accuracy of the equivalent circuit model by using a plurality of polarization terms.

When the current I is applied to the secondary battery 100, the closed circuit voltage CCV, which is the voltage between the terminals of the secondary battery 100, is expressed by the following equation (3). In Expression (3), Vp is a polarization voltage, and I · R corresponds to a voltage across a parallel connection pair of the resistor 202 and the capacitor 203.
CCV = OCV + I · R + Vp (3)

The open circuit voltage OCV is used to calculate the SOCv, but cannot be directly measured while the secondary battery 100 is being charged / discharged. Therefore, the SOCv calculation unit 113 obtains the open circuit voltage OCV by subtracting the IR drop and the polarization voltage Vp from the closed circuit voltage CCV as in the following equation (4).
OCV = CCV-I.R-Vp (4)

  The correspondence relationship between the open circuit voltage OCV and the SOC is determined by the characteristics of the secondary battery 100, and data defining the correspondence relationship is stored in advance as an SOC table in a storage unit (not shown). The SOCv calculation unit 113 calculates the open circuit voltage OCV using the above-described equation (4), and calculates the SOCv of the secondary battery 100 by referring to the SOC table using this as a key.

FIG. 3 is a diagram illustrating a configuration of the SOH calculation unit 110.
Similar to the SOHQ calculation unit 115, the SOH calculation unit 110 will be described using an example configured to calculate SOHQ that is a capacity deterioration rate. The SOHQ calculation unit 115 includes a battery voltage estimation unit 303, an SOCv error calculation unit 304, an SOCv 2-point selection unit 300, a current integration unit 301, a Qmax _SOCv calculation unit 302, a final Qmax ′ calculation unit 305, and an SOHQ conversion unit 306. .

The battery voltage estimation unit 303 estimates the battery voltage based on the information on the equivalent circuit model of the battery. A calculation example of the estimated battery voltage _Vcalc will be described later. The SOCv error calculation unit 304 calculates a value obtained by subtracting the estimated battery voltage _Vcalc from the battery voltage V input from the voltage sensor 108, that is, an error α between the battery voltage V and the estimated battery voltage _Vcalc . The SOCv 2-point selection unit 300 selects two SOCv points, that is, SOCv1 and 2 when the absolute value of the error α is equal to or smaller than the predetermined value V _threshold . Although a specific example of the two-point selection will be described later, the current I detected by the current sensor 106 may also be referred to. The current integration unit 301 integrates the current values that flow between the selected SOCv1 and 2, and calculates the charge / discharge capacity ∫Idt between the SOCv1 and SOCv2. Qmax _SOCv computing unit 302 computes full charge capacity Qmax _SOCv using SOCv1, 2 and ∫Idt. The final Qmax ′ calculator 305 calculates final Qmax ′ by performing an averaging process using the input full charge capacity Qmax _SOCv and the previous result Qmax_z of the Qmax ′ calculation. The SOHQ conversion unit 306 calculates SOHQ by comparing the final Qmax ′ with the full charge capacity Qmax when new.

Next, the operation of the SOH calculation unit 110 will be described.
The SOCv2 point selection unit 300 selects two SOCv1 and SOCv2 that are appropriate for calculation from the SOCv sequentially output from the SOCv calculation unit 113. As described above, the SOCv calculation unit 113 calculates the SOCv by estimating the OCV using the equivalent circuit model of the secondary battery 100. It is important that the equivalent circuit model of the battery has little error, selects a value close to the true SOC value and the SOCv, and selects two appropriate SOCv points.

  Hereinafter, selection condition 1 for selecting a point where the difference between the voltage value calculated by the equivalent circuit model of the battery and the measured battery voltage is small will be described as a selection condition for selecting two SOCvs. The selection conditions 2 to 7 will be described later.

[Selection condition 1: Select a point where the difference between the calculated voltage value of the battery equivalent circuit model and the measured battery voltage is small]
The battery voltage estimation unit 303 estimates the battery voltage based on the information of the equivalent circuit model of the battery by the following equation (5).

The OCV (SOC) is an OCV obtained by referring to the SOC obtained from the SOC calculation unit 109 based on the formula (1) based on the correspondence relationship (SOC table) between the SOC and the OCV stored in the storage unit in advance. It is. The internal resistance voltage V ₀ and the polarization voltage Vp are values shown by an equivalent circuit model of the secondary battery 100. Battery voltage estimation unit 303 outputs battery voltage V _calc estimated by equation (5) to SOCv error calculation unit 304.
Note that the OCV (SOC) described in Equation (5) is the correspondence between the SOC and OCV stored in advance in the storage unit (SOC) based on the SOCi calculated based on Equation (2) by the SOCi computing unit 112. The OCV obtained from the table may be used. In the present embodiment, these OCVs are referred to as second open circuit voltages.

The SOCv error calculation unit 304 calculates the error α by taking the difference between the battery voltage V input from the voltage sensor 108 and V _calc . The following expression (6) is an arithmetic expression for the error α.

When the absolute value of the error α is equal to or less than the predetermined value V _threshold , the SOCv2 point selection unit 300 is validated, and two points of SOCv1 and SOCv2 are selected and output to the subsequent calculation units. On the other hand, when the absolute value of the error α is larger than the predetermined value V _threshold , two points of SOCv are not selected and are not output to the subsequent calculation units. With such a configuration, it is possible to select an SOCv with little error.

FIG. 4A shows _{changes in} the measured battery voltage V and the model estimated voltage _Vcalc input from the voltage sensor. FIG. 4B shows the transition of the error α. In FIG. 4B, the dotted line indicates the positive / negative determination predetermined value V _threshold . As shown in FIG. 4A, _Vcalc deviates from the measured voltage at time t1 when a large current is input and a sudden voltage fluctuation occurs, or at time t2 when the current is applied for a long time. The error α captures such a timing, so that an SOCv with poor accuracy is not selected. Since the accuracy of SOHQ is improved by reducing the predetermined value V _{threshold The,} the predetermined value V _{threshold The} determining based on an acceptable SOHQ error.

  5A and 5B are diagrams showing the relationship between the error α and the SOCv calculation error. FIG. 5A shows transition of the SOC true value and the SOCv. FIG. 5B shows the error α. A portion surrounded by a dotted circle in the figure is a portion where the SOCv deviates from the true value. At the same timing, as shown in FIG. 5B, the value of the error α also increases, and it can be confirmed that the error α is equal to or greater than the threshold value. From this, it is possible to detect the SOCv error by determining the error α, and to select SOCv1 and SOCv2 with a small error.

ここで、ΔＳＯＣｖ＝｜ＳＯＣｖ１−ＳＯＣｖ２｜である。 Current integration unit 301 integrates the current values that flow between SOCv1 and SOCv2 selected under the above conditions, and calculates charge / discharge capacity ∫Idt between SOCv1 and SOCv2. Qmax _SOCv computing unit 302 computes full charge capacity Qmax _SOCv by the following equation (7) using SOCv1, SOCv2 and ∫Idt.

Here, ΔSOCv = | SOCv1-SOCv2 |.

ここで、Ｎとは平均化のサンプリング数である。Ｑｍａｘ’は急激に変動しないため、前回値とＮを使用し、演算値の平滑化を図っている。 The Qmax _SOCv calculated in this way is output to the final Qmax ′ calculator 305. The final Qmax ′ calculation unit 305 calculates the final Qmax ′ by performing the previous result Qmax_z of the Qmax ′ calculation and the averaging process represented by Expression (8).

Here, N is the number of samplings for averaging. Since Qmax ′ does not fluctuate rapidly, the previous value and N are used to smooth the calculation value.

  FIG. 6 is a diagram showing the transition of Qmax ′. In this figure, the horizontal axis represents time, the vertical axis represents Qmax ', the dotted line in the figure indicates the case before the present embodiment is applied, and the solid line in the figure indicates the case where the present embodiment is applied. Before applying this embodiment, selecting an SOCv with a large SOCv calculation error increases the error and deviates greatly from the true value. After the application of this embodiment, only accurate SOCv is selected, so it can be confirmed that the calculation of Qmax 'is highly accurate.

The SOHQ conversion unit 306 receives the smoothed Qmax ′ and calculates SOHQ by comparing Qmax ′ with the full charge capacity Qmax when new. The arithmetic expression is the following expression (9).

By adopting such a configuration, it is possible to calculate a SOHQ by selecting a point with a small SOCv calculation error, and thus a highly accurate SOHQ calculation is possible.

  In the above description, the selection condition 1 for selecting the point where the difference between the voltage value calculated by the equivalent circuit model of the battery and the measured battery voltage is small is selected as the selection condition for selecting two SOCv points. As a condition for selecting two SOCv points, any one or two or more of selection conditions 2 to 7 described below may be selected. As a result, the full charge capacity can be accurately calculated.

[Selection condition 2: Select under the condition that the absolute value of the current is small]
When the current flowing through the secondary battery 100 is large, the SOCv calculation unit 113 calculates the product of the current I and the resistance 201, so that an error as a calculation result is enlarged. When selecting SOCv1 and SOCv2, it is possible to select a point where the error of the product of the current I and the resistance 201 is small, that is, the SOCv error is small, by selecting each under the condition that the current is small. Therefore, SOCv1 and SOCv2 respectively select points where the current is small.

[Selection condition 3: Select two points within the specified battery temperature]
The values of the resistance 201 and the polarization section resistance 202 change depending on the battery temperature. In particular, when the temperature is low, the resistance increases, and there is a concern that the error in the product of the current I and the resistance 201 may increase. Further, it is known that the resistance changes depending on the current in the low temperature region, and the error condition to be considered increases. It is preferable to select two temperatures of about room temperature. In addition, if the calculation is performed at a temperature higher than the temperature at which the battery should be originally used, an unexpected error may occur, which is not appropriate. Therefore, SOCv1 and SOCv2 each select a point whose temperature is within a predetermined value range.

[Selection condition 4: Select two points where ΔSOCv is a predetermined value or more]
Even when the errors of SOCv1 and SOCv2 are large, if two points with large ΔSOCv = | SOCv1-SOCv2 | can be selected, the influence of the error of each SOCv is reduced, and the calculation accuracy of the full charge capacity is improved. Therefore, the two SOCv points are selected so that ΔSOCv is larger than a predetermined value.

[Selection condition 5: Select two points where the current signs of SOCv1 and SOCv2 are the same]
In the equivalent circuit model of the secondary battery 100, the values of the resistance 201 and the polarization section resistance 202 may differ between charging and discharging. Therefore, by selecting the SOCv1 current code and the SOCv2 current code to be the same, an error due to the difference between the charging resistance and the discharging resistance can be excluded. Therefore, the same point is selected for the signs of the two currents of SOCv.

[Selection condition 6: Select two points at which the time until SOCv1 and SOCv2 is less than or equal to a predetermined value]
If the time from SOCv1 to SOCv2 is long, there is a risk that the error may diverge due to accumulation of offset error or the like of the current sensor 106. Therefore, a point where the detection times of SOCv1 and SOCv2 are not separated by a predetermined time t _threshold or more is selected.

[Selection condition 7: Select two points with the same sign of the error α between the voltage value calculated by the equivalent circuit model of the battery and the measured battery voltage]
The calculation accuracy of the full charge capacity is improved by selecting two SOCvs having the same sign of the error value α between the voltage value calculated by the battery equivalent circuit model and the measured battery voltage. FIG. 7 is a diagram showing an OCV approximate curve during charging and discharging. In this figure, the horizontal axis represents SOC, the vertical axis represents OCV, a represents an OCV approximate curve including an error due to charge polarization, and b represents an OCV approximate curve including an error due to discharge polarization. It is assumed that the equivalent circuit model of the battery cannot correctly represent the actual battery, and the SOCv is selected in a state where polarization remains on the discharge side or polarization remains on the charge side. If two SOCvs are selected on the discharge sides, the error directions derived from the discharge polarization coincide with each other, so the errors cancel out between the two points. However, if it is obtained by charging and discharging, an error derived from polarization remains. For this reason, it is desirable that the error directions are aligned and the errors are cancelled. The sign of the error α between the voltage value calculated by the equivalent circuit model of the secondary battery 100 and the measured battery voltage corresponds to the error direction. Therefore, two points having the same sign of the error value α between the voltage value calculated by the equivalent circuit model of the battery and the measured battery voltage are selected.

  According to the first embodiment, it is possible to determine the SOCv error calculated from the battery equivalent circuit model by comparing the measured voltage with the voltage of the battery equivalent circuit model. This makes it possible to select two highly accurate SOCvs used for the SOHQ calculation.

-Second Embodiment-
FIG. 8 is a diagram illustrating the configuration of the SOH calculation unit according to the second embodiment.
The same parts as those in the configuration of the SOH calculation unit according to the first embodiment shown in FIG. The difference from the first embodiment is that a weight calculation unit 400 and a weighted calculation averaging Qmax ′ calculation unit 401 are added. In the first embodiment, the SOCv selection unit 300 selects two highly accurate SOCvs, but there are differences in expected accuracy depending on the selection conditions of the two SOCv points. Since the full charge capacity can be calculated with high accuracy by the calculation result selected under a condition with high accuracy, it is desirable that the calculation result be largely reflected in the final result. Therefore, based on the two-point selection condition in the SOCv 2-point selection unit 300, the weight calculation unit 400 calculates the following weight W, and the weighted calculation averaging Qmax ′ calculation unit 401 performs weighted averaging, thereby achieving high accuracy. The results are greatly reflected in the final results.

The weight W will be described below.
[Weight 1: A weight is set based on the difference α between the voltage value calculated by the battery equivalent circuit model and the measured battery voltage]
As described in the selection condition 1 of the first embodiment, as the error α calculated by the SOCv error calculation unit 304 is smaller, the SOCv error is smaller and the accuracy of the full charge capacity is improved. Therefore, the weight is set based on the error α. For example, the weight 1 shown by the following formula (10) is introduced.

  Instead of the weight 1, any one of the following weight 2 and weight 3 may be selected and used. By adding subsequent weights, the full charge capacity can be calculated with high accuracy. When using these weights, for example, the product of these weights may be used as the final weight W.

[Weight 2: Set weight based on ΔSOCv]
As described in the selection condition 4 of the first embodiment, the accuracy of the SOHQ calculation improves as ΔSOCv = | SOCv1-SOCv2 | increases. Therefore, the weight is set based on ΔSOCv. For example, the weight shown by the following formula (11) is introduced.

[Weight 3: Set weight based on time to SOCv1 and SOCv2]
As described in the selection condition 6 of the first embodiment, a shorter time between the SOCv1 and the SOCv2 is less affected by an offset error or the like of the current sensor 106, and can be highly accurate. Therefore, the weight is set based on the time between SOCv1 and SOCv2. For example, the weight shown by the following formula (12) is introduced. t _threshold indicates the predetermined time indicated by the selection condition 6 of the first embodiment.

ここで、Ｑｍａｘ’_ｚは、式（１３）の前回の演算結果である。 In this way, the weight W calculated by the weight calculation unit 400 is output to the weighted average Qmax ′ calculation unit 401. The weighted average Qmax ′ calculation unit 401 performs weighted average using the Qmax _SOCv calculation result in the Qmax _SOCv calculation unit 302 and the weight W calculated under the condition at the time of the calculation. The weighted average is performed by the following equation (13).

Here, Qmax′_z is the previous calculation result of Expression (13).

  According to the second embodiment, by weighted averaging, highly reliable data is largely reflected, so that the accuracy can be improved and the convergence to the true value can be accelerated.

-Third embodiment-
FIG. 9 is a diagram illustrating a configuration of the second SOC calculation unit 114 according to the third embodiment.
In the third embodiment, a second SOC calculation unit 114 is provided as an SOC calculation unit in place of the SOC calculation unit 109 in the first embodiment. Other configurations are the same as those in FIG. 1, and the description thereof is omitted.
Second SOC calculation unit 114 includes first SOC calculation unit 109A, battery voltage estimation unit 303, SOCv error calculation unit 304, and final SOC calculation unit 500.

  The first SOC calculation unit 109A is the same as the SOC calculation unit 109 described in the first embodiment, and includes the SOCi calculation unit 112 and the SOCv calculation unit 113, and the equation (1) described in the first embodiment. ) To calculate the SOC. The calculated SOC is transmitted to the battery voltage estimation unit 303.

  The SOCi calculation unit 112 is the same as that described in the first embodiment, and obtains the SOCi of the secondary battery 100 by accumulating the current I charged and discharged by the secondary battery 100 according to the equation (2). And output to the final SOC calculation unit 500.

  The SOCv calculation unit 113 is the same as the content described in the first embodiment, calculates the SOCv from the equivalent circuit model of the secondary battery 100, V0 and Vp to the battery voltage estimation unit 303, and the final SOCv. The data is output to the SOC calculation unit 500.

The battery voltage estimation unit 303 is similar to the content described in the first embodiment, and outputs the battery voltage V _calc estimated by the equation (5) to the SOCv error calculation unit 304. OCV (SOC) is an OCV obtained from the correspondence (SOC table) between the SOC and the OCV stored in advance in the storage unit based on the SOC obtained by the SOC calculation unit 109 based on the expression (1). V ₀ and Vp are values shown in the equivalent circuit model of the secondary battery 100.
Note that the OCV (SOC) described in Equation (5) is the correspondence between the SOC and OCV stored in advance in the storage unit (SOC) based on the SOCi calculated based on Equation (2) by the SOCi computing unit 112. The OCV obtained from the table may be used. In the present embodiment, these OCVs are referred to as second open circuit voltages.

The SOCv error calculation unit 304 calculates the error α based on the equation (6) by taking the difference between the battery voltages V and _Vcalc input from the voltage sensor 108, and outputs the error α to the final SOC calculation unit 500.

SOCv and SOVi are input to the final SOC calculation unit 500, and the final SOC calculation unit 500 calculates the final SOC based on the value of the error α. For example, if the error α is equal to or less than a predetermined value V _threshold , it is determined that the SOCv error is small, and the SOCv is output to the subsequent stage as the final SOC. When the error α is larger than the predetermined value V _threshold , the charging rate SOCi is output to the subsequent stage as the final SOC.
Note that the weight W1 may be calculated from the value of the error α according to the equation (10), and weighted and averaged according to the equation (1), where W1 = W.

  According to this embodiment, since the final SOC is selected from the SOCv and SOCi based on the error α and determined, a reliable calculation result can be reflected, so that the calculation of the SOC can be highly accurate. .

According to the embodiment described above, the following operational effects can be obtained.
(1) The secondary battery control apparatus 102 includes a polarization component represented by a parallel connection of a polarization resistance and a capacity component, and an equivalent circuit having at least an internal resistance component R of the secondary battery 100. The first open circuit voltage OCV is obtained, and the charging rate SOCv of the secondary battery 100 is obtained from the relationship between the first open circuit voltage OCV and the charging rate of the secondary battery 100. Then, the secondary battery control device 102 calculates the value of the second open circuit voltage calculated from the measured voltage value of the secondary battery 100 by a method different from the first open circuit voltage OCV, and current information of the secondary battery 100. A value obtained by subtracting the voltage value Vp of the polarization component calculated according to the above and the value RI represented by the product of the internal resistance component R and the current value I of the secondary battery 100 is calculated. Thereby, the difference between the measured voltage value of secondary battery 100 and the calculated value of SOCv can be obtained.

(2) The secondary battery control device 102 includes a first component of the secondary battery 100 from an equivalent circuit having at least a polarization component represented by a parallel connection of a polarization resistance and a capacity component, and an internal resistance component of the secondary battery 100. The SOCv calculation unit 113 that obtains the open circuit voltage OCV and obtains the charge rate SOCv of the secondary battery from the correspondence between the first open circuit voltage OCV and the charge rate SOC of the secondary battery is different from the first open circuit voltage OCV. Based on the second open circuit voltage OCV, the voltage value Vp of the polarization component calculated according to the current information of the secondary battery, and the value RI represented by the product of the internal resistance component R and the current value I of the secondary battery A battery voltage estimation unit 303 that estimates the battery voltage, and an SOCv error calculation unit 304 that calculates an error α between the battery voltage V _calc estimated by the battery voltage estimation unit 303 and the measured voltage of the secondary battery are provided. Thereby, the error of the calculation of SOCv can be calculated.

(3) The secondary battery control device 102 includes an SOCi calculation unit 112 that calculates the charging rate SOCi of the secondary battery 100 obtained by integrating the current charged and discharged by the secondary battery 100, and the battery voltage estimation unit 303 includes The value of the second open circuit voltage is obtained with reference to the charging rate SOCi based on the correspondence relationship between the first open circuit voltage and the charging rate SOC of the secondary battery. Thereby, the error of the calculation of SOCv can be calculated.

(4) The secondary battery control device 102 obtains the charge rate SOC by weighting and adding the charge rate SOCi and the charge rate SOCv, and the battery voltage estimation unit 303 calculates the value of the second open circuit voltage as the first open circuit voltage. The charging rate SOC is calculated with reference to the weighted and added charging rate SOC based on the correspondence relationship between the charging rate SOC and the charging rate SOC of the secondary battery. Thereby, the error of the calculation of SOCv can be calculated with higher accuracy.

(5) The secondary battery control device 102 integrates the current value that has flowed through the secondary battery between the charging rate SOCv1 and the charging rate SOCv2 at least two points of the charging rate SOCv to calculate the charge / discharge capacity. Unit 301 and a SOHQ calculation unit 115 that calculates the capacity deterioration rate SOHQ of the secondary battery using at least two points of charge rate SOCv1, charge rate SOCv2, and the current integration value of the secondary battery, and SOHQ calculation unit 115 Calculates the capacity deterioration rate SOHQ or makes the calculated capacity deterioration rate SOHQ valid when the error calculated by the error calculation unit 304 is equal to or less than a predetermined value. This makes it possible to select two highly accurate SOCvs used for the SOHQ calculation.

(6) The secondary battery control device 102 includes a selection unit 300 that selects two points of charge rate SOCv1 and charge rate SOCv2 from the charge rate SOCv output from the SOCv calculation unit 113, and the selection unit 300 includes an error. Is small, two-point charge rate SOCv1 and charge rate SOCv2 are selected. Thereby, the error of the calculation of SOCv can be calculated with higher accuracy.

(7) The secondary battery control apparatus 102 includes a selection unit 300 that selects two points of charge rate SOCv1 and charge rate SOCv2 from the charge rate SOCv output from the SOCv calculation unit 113. When the absolute value of the current flowing through the secondary battery 100 is small, the two points of charge rate SOCv1 and charge rate SOCv2 are selected. Thereby, the error of the calculation of SOCv can be calculated with higher accuracy.

(8) The secondary battery control device 102 includes a selection unit 300 that selects two points of charge rate SOCv1 and charge rate SOCv2 from the charge rate SOCv output from the SOCv calculation unit 113. When the temperature of the secondary battery 100 is within a predetermined value, two points of charge rate SOCv1 and charge rate SOCv2 are selected. Thereby, the error of the calculation of SOCv can be calculated with higher accuracy.

(9) The secondary battery control apparatus 102 includes a selection unit 300 that selects two points of charge rate SOCv1 and charge rate SOCv2 from the charge rate SOCv output from the SOCv calculation unit 113. The selection unit 300 is charged Two points of charge rate SOCv1 and charge rate SOCv2 having a large difference between rate SOCv1 and charge rate SOCv2 are selected. Thereby, the error of the calculation of SOCv can be calculated with higher accuracy.

(10) The secondary battery control apparatus 102 includes a selection unit 300 that selects two charging rate SOCv1 and charging rate SOCv2 from the charging rate SOCv output from the SOCv calculation unit 113. The charging rate SOCv1 and the charging rate SOCv2 when the secondary battery 100 is discharged, or the charging rate SOCv1 and the charging rate SOCv2 when the secondary battery 100 is charged are selected. Thereby, the error of the calculation of SOCv can be calculated with higher accuracy.

(11) The secondary battery control apparatus 102 includes a selection unit 300 that selects two points of charge rate SOCv1 and charge rate SOCv2 from the charge rate SOCv output from the SOCv calculation unit 113. The selection unit 300 is charged The charging rate SOCv1 and the charging rate SOCv2 at two points where the detection times of the rate SOCv1 and the charging rate SOCv2 are not separated by a predetermined time or longer are selected. Thereby, the error of the calculation of SOCv can be calculated with higher accuracy.

(12) The secondary battery control apparatus 102 includes a selection unit 300 that selects two points of charge rate SOCv1 and charge rate SOCv2 from the charge rate SOCv output from the SOCv calculation unit 113. Are the same, two points of charge rate SOCv1 and charge rate SOCv2 are selected. Thereby, the error of the calculation of SOCv can be calculated with higher accuracy.

(13) The secondary battery control apparatus 102 includes a weighted average Qmax ′ calculating unit 401 that performs weighted averaging of the capacity deterioration rate SOHQ. The weighted average Qmax ′ calculating unit 401 performs capacity deterioration rate by weighting based on an error. SOHQ is calculated. As a result, highly reliable data is greatly reflected, so that the accuracy can be improved and the convergence to the true value can be accelerated.

(14) The secondary battery control apparatus 102 calculates the charging rate SOCi of the secondary battery 100 obtained by integrating the charging / discharging current of the secondary battery 100, the charging rate SOCi, and the charging rate SOCv. The first SOC calculation unit 109A that obtains the charging rate SOC by weighting and the battery voltage estimation unit 303 calculates the value of the second open circuit voltage, the open circuit voltage OCV of the secondary battery 100, and the charging of the secondary battery. The second SOC calculation unit 114 outputs the charge rate SOCv as an appropriate value when the error is equal to or less than a predetermined value, and the error is determined from the predetermined value based on the correspondence with the rate SOC. If larger, the charging rate SOCi is output as an appropriate value. Thereby, since a reliable calculation result can be reflected, it is possible to increase the accuracy of the calculation of the SOC.

  The present invention is not limited to the above-described embodiment, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention as long as the characteristics of the present invention are not impaired. .

1: battery system 100: secondary battery 101: battery information acquisition unit 102: secondary battery control device 103: host controller 104: inverter 105: load 106: current sensor 107: temperature sensor 108: voltage sensor 109: SOC calculation unit 109A : First SOC calculation unit 110: SOH calculation unit 111: allowable current calculation unit 112: SOCi calculation unit 113: SOCv calculation unit 114: second SOC calculation unit 115: SOHQ calculation unit 200: OCV
201: DC resistance 202: Polarization resistance 203: Polarization capacitor 300: SOCv2 point selection unit 301: Current integration unit 302: Qmax _SOCv calculation unit 303: Battery voltage estimation unit 304: SOCv error calculation unit 305: Final Qmax ′ calculation unit 306: SOHQ converter 400: weight calculator
401: Weighted average Qmax 'calculation unit 500: Final SOC calculation unit

Claims (14)

A first open circuit voltage OCV of the secondary battery is obtained from an equivalent circuit having at least a polarization component represented by a parallel connection of a polarization resistance and a capacitance component, and an internal resistance component R of the secondary battery, and the first open circuit voltage OCV is obtained. A secondary battery control device for obtaining a charging rate SOCv of the secondary battery from a relationship between a circuit voltage OCV and a charging rate of the secondary battery,
The secondary battery control device uses a measured voltage value of the secondary battery as a second open circuit voltage value calculated by a method different from the first open circuit voltage OCV, and current information of the secondary battery. A secondary battery control device for calculating a value obtained by subtracting the voltage value Vp of the polarization component calculated in response to the value RI and the value RI represented by the product of the internal resistance component R and the current value I of the secondary battery . A first open circuit voltage of the secondary battery is obtained from an equivalent circuit having at least a polarization component represented by parallel connection of a polarization resistance and a capacity component and an internal resistance component of the secondary battery, and the first open circuit voltage And a SOCv calculation unit for obtaining a charge rate SOCv of the secondary battery from a correspondence relationship between the charge rate SOC of the secondary battery and SOC
A product of a second open circuit voltage different from the first open circuit voltage, a voltage value of the polarization component calculated according to current information of the secondary battery, and a current value of the internal resistance component and the secondary battery A battery voltage estimator that estimates the battery voltage based on the value represented by
An error calculator that calculates an error between the battery voltage estimated by the battery voltage estimator and the measured voltage of the secondary battery;
A secondary battery control device comprising: The secondary battery control device according to claim 2,
A SOCi calculating unit for calculating a charging rate SOCi of the secondary battery obtained by integrating currents charged and discharged by the secondary battery;
The battery voltage estimation unit obtains a value of the second open circuit voltage with reference to the charge rate SOCi based on a correspondence relationship between the first open circuit voltage and the charge rate SOC of the secondary battery. Secondary battery control device. The secondary battery control device according to claim 3,
The charging rate SOC is obtained by weighted addition of the charging rate SOCi and the charging rate SOCv,
The battery voltage estimation unit refers to the charge rate SOC obtained by weighting and adding the value of the second open circuit voltage based on a correspondence relationship between the first open circuit voltage and the charge rate SOC of the secondary battery. Secondary battery control device. In the secondary battery control device according to any one of claims 2 to 4,
A current integrating unit that calculates the charge / discharge capacity by integrating the current value that has flowed through the secondary battery while indicating the charging rate SOCv1 and the charging rate SOCv2 of at least two points of the charging rate SOCv;
A SOHQ calculator that calculates a capacity deterioration rate SOHQ of the secondary battery using the charge rate SOCv1, the charge rate SOCv2 of the at least two points, and a current integral value of the secondary battery;
With
The SOHQ operation unit
A secondary battery control device that calculates a capacity deterioration rate SOHQ or makes the calculated capacity deterioration rate SOHQ valid when an error calculated by the error calculation unit is a predetermined value or less. The secondary battery control device according to claim 5,
A selection unit that selects a charging rate SOCv1 and a charging rate SOCv2 at two points from the charging rate SOCv output from the SOCv calculation unit;
The selection unit is a secondary battery control device that selects the charging rate SOCv1 and the charging rate SOCv2 of the two points when the error is small. The secondary battery control device according to claim 5,
A selection unit that selects a charging rate SOCv1 and a charging rate SOCv2 at two points from the charging rate SOCv output from the SOCv calculation unit;
The selection unit is a secondary battery control device that selects the charging rate SOCv1 and the charging rate SOCv2 at the two points when the absolute value of the current flowing through the secondary battery is small. The secondary battery control device according to claim 5,
A selection unit that selects a charging rate SOCv1 and a charging rate SOCv2 at two points from the charging rate SOCv output from the SOCv calculation unit;
The selection unit is a secondary battery control device that selects the charging rate SOCv1 and the charging rate SOCv2 of the two points when the temperature of the secondary battery is within a predetermined value. The secondary battery control device according to claim 5,
A selection unit that selects a charging rate SOCv1 and a charging rate SOCv2 at two points from the charging rate SOCv output from the SOCv calculation unit;
The selection unit is a secondary battery control device that selects the charging rate SOCv1 and the charging rate SOCv2 at the two points where the difference between the charging rate SOCv1 and the charging rate SOCv2 is large. The secondary battery control device according to claim 5,
A selection unit that selects a charging rate SOCv1 and a charging rate SOCv2 at two points from the charging rate SOCv output from the SOCv calculation unit;
The selection unit selects two points of the charge rate SOCv1 and the charge rate SOCv2 when the secondary battery is discharged, or the charge rate SOCv1 and the charge rate SOCv2 when the secondary battery is charged. Control device. The secondary battery control device according to claim 5,
A selection unit that selects a charging rate SOCv1 and a charging rate SOCv2 at two points from the charging rate SOCv output from the SOCv calculation unit;
The selection unit is a secondary battery control device that selects the two points of charge rate SOCv1 and charge rate SOCv2 whose detection times of the charge rate SOCv1 and the charge rate SOCv2 are not separated by a predetermined time or more. The secondary battery control device according to claim 5,
A selection unit that selects a charging rate SOCv1 and a charging rate SOCv2 at two points from the charging rate SOCv output from the SOCv calculation unit;
The selection unit is a secondary battery control device that selects the charging rate SOCv1 and the charging rate SOCv2 of the two points when the sign of the error is the same. The secondary battery control device according to claim 5,
A weighted averaging operation unit for performing weighted averaging of the capacity deterioration rate SOHQ;
The weighted averaging calculation unit is a secondary battery control device that calculates the capacity deterioration rate SOHQ by weighting based on the error. The secondary battery control device according to claim 2,
A SOCi calculating unit for calculating a charging rate SOCi of the secondary battery obtained by integrating currents charged and discharged by the secondary battery;
An SOC calculation unit that obtains a charge rate SOC by weighting and adding the charge rate SOCi and the charge rate SOCv;
The battery voltage estimation unit refers to the charge rate SOC obtained by weighting and adding the value of the second open circuit voltage based on the correspondence between the open circuit voltage OCV of the secondary battery and the charge rate SOC of the secondary battery. Ask
The SOC calculation unit outputs the charging rate SOCv as an appropriate value when the error is less than or equal to a predetermined value, and outputs the charging rate SOCi as an appropriate value when the error is greater than a predetermined value. Control device.

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