JP2016024149A - Method of estimating state of secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique which makes it possible to accurately estimate the full charge capacity of a secondary battery for a running electric vehicle.SOLUTION: According to a difference (ΔT) between an estimation value Ts of an internal temperature of a secondary battery calculated in a process to estimate an SOC (state of charge) of the secondary battery using a battery reaction model and a measured value T of an external temperature, a full charge capacity of the battery reaction model is corrected.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a state estimation method for a secondary battery. More specifically, the present invention provides a secondary battery capable of accurately estimating the full charge capacity of a secondary battery and accurately estimating the charge rate SOC of the secondary battery even when not in a completely relaxed state. It relates to the state estimation method.

  In response to the recent increase in global environmental protection awareness, for example, an electric vehicle (for example, an electric vehicle (EV), which includes an electric motor that generates a driving force by electric power supplied from a secondary battery such as a lithium ion battery) In recent years, plug-in hybrid vehicles (PHV), hybrid vehicles (HV), and the like) have spread rapidly.

  By the way, there is a possibility that the battery performance of the secondary battery is deteriorated due to overdischarge and / or overcharge, and the life is shortened. Therefore, from the viewpoint of maintaining the performance and life of the secondary battery, the state of charge (SOC) of the secondary battery is accurately estimated, the charge / discharge of the secondary battery is appropriately controlled, and excessive charge / discharge is performed. It is necessary to suppress discharge. It is also important to accurately estimate the SOC of the secondary battery in order to correctly determine whether or not the amount of electric power necessary to drive the electric vehicle to the destination is secured.

  Therefore, in the technical field, various methods for accurately estimating the state of the secondary battery have been proposed. For example, an attempt has been made to predict the thermal behavior and electrochemical behavior of a lithium ion battery using a battery reaction model based on an electrochemical reaction equation (see, for example, Non-Patent Document 1). The disclosure in Document 1 is incorporated herein by reference), and a technique for estimating the SOC of a secondary battery using such a battery reaction model has also been developed.

  Specifically, for example, the SOC and battery current are estimated by estimating the internal state of the secondary battery using a battery reaction model, and the error between the integrated value of the estimated value of the battery current with respect to the SOC and the integrated value of the actually measured value. And a technology for estimating the capacity deterioration parameter based on the error has been proposed (see, for example, Patent Literature 1. The disclosure in Patent Literature 1 is incorporated herein by reference).

  In addition, for example, a technique for estimating a temperature corresponding to the internal resistance of a power storage element using a temperature outside the power storage element and an expression representing heat transfer has been proposed (see, for example, Patent Document 2). Note that the disclosure of Patent Document 2 is incorporated herein by reference).

JP 2010-060384 A JP 2013-118056 A

W. B. Gu and C.M. Y. Wang, “Thermal and Electrochemical Coupled Modeling of a Lithium-Ion Cell, in Lithium Batteries”, ECS Proceedings, Vol. 99-25 (1), pp. 748-762, 2000

  As described above, in this technical field, various techniques for estimating the SOC and the battery temperature by estimating the internal state of the secondary battery using the battery reaction model have been proposed. By the way, the SOC of the secondary battery at a specific time indicates the ratio of the charge capacity (remaining electric energy) of the secondary battery at that time to the full charge capacity. Therefore, in order to accurately estimate the SOC of the secondary battery, it is necessary to acquire an accurate full charge capacity of the secondary battery. Further, since the value of the full charge capacity changes (usually decreases) due to the passage of time and deterioration due to the load, it is necessary to continuously acquire the full charge capacity. Furthermore, in order to accurately estimate the full charge capacity of the secondary battery, it is necessary to obtain an accurate open circuit voltage (OCV) of the secondary battery.

  In order to acquire the accurate OCV of the secondary battery, it is necessary to acquire the voltage between the terminals of the secondary battery in the completely relaxed state. However, for example, since it is rare that a secondary battery is in a completely relaxed state in a traveling electric vehicle, it is difficult to obtain an accurate OCV of the secondary battery, and as a result, the full charge capacity of the secondary battery It is also difficult to estimate accurately. If an accurate full charge capacity of a secondary battery cannot be obtained, the difference between the estimated value and the true value of the secondary battery becomes large, and as described above, excessive charge of the secondary battery is excessive. It is difficult to suppress discharge or to accurately determine whether the amount of power necessary to drive the electric vehicle to the destination is secured by estimating the accurate remaining power amount of the secondary battery There is a risk of becoming.

  That is, in the technical field, there is a need for a technique that makes it possible to accurately estimate the full charge capacity of a secondary battery in a traveling electric vehicle. In other words, one object of the present invention is to provide a technique that makes it possible to accurately estimate the full charge capacity of a secondary battery in a traveling electric vehicle.

  Therefore, as a result of earnest research, the present inventor has found that the estimated value Ts of the internal temperature of the battery calculated in the process of estimating the SOC of the secondary battery using the battery reaction model and the detection means disposed outside the battery. By correcting the full charge capacity of the battery reaction model according to the difference (ΔT) from the measured value T of the external temperature of the battery obtained from (for example, a temperature sensor), the full charge capacity of the secondary battery can be accurately determined. (It will be described later in detail).

Therefore, the above one object of the present invention is to
A state estimation method for a secondary battery that estimates a full charge capacity and an internal temperature of the secondary battery using a battery reaction model,
Calculate the temperature difference ΔT of the secondary battery from the estimated value Ts of the internal temperature of the secondary battery and the measured value T of the external temperature according to the following formula (1):

When the temperature difference ΔT is larger than a predetermined upper limit Tu, the full charge capacity of the battery reaction model is corrected to a smaller value.
This is achieved by a state estimation method for a secondary battery.

  According to the present invention, by correcting the full charge capacity of the battery reaction model based on the internal temperature of the secondary battery estimated using the battery reaction model as described above, even in an electric vehicle that is running, The full charge capacity of the secondary battery can be accurately estimated.

It is a typical graph showing the difference by the full charge capacity of the said battery reaction model of the time transition of SOC of a secondary battery estimated using a battery reaction model. It is a typical graph showing the correspondence of the open circuit voltage OCV and full charge capacity Qf of the battery reaction model used in the state estimation method of a secondary battery. Changes over time of the open-circuit voltage OCV and the battery voltage V when the open-circuit voltage OCV of the battery reaction model used in the secondary battery state estimation method is accurately estimated (a) and overestimated (b) It is a typical graph showing. It is a typical graph explaining the correction | amendment procedure of the full charge capacity of the battery reaction model used in the state estimation method of the secondary battery which concerns on one embodiment of this invention. It is a typical graph explaining the influence on correction | amendment of a full charge capacity by accumulation | storage of the measurement error of the detection means of the battery temperature. When the fuse of any one of the plurality of unit cells constituting the secondary battery is disconnected and the full charge capacity is rapidly reduced (a), and the electrode of the battery is configured by, for example, a high load or impact It is a schematic diagram explaining the case (b) where the active material to be lost is lost and the full charge capacity rapidly decreases. It is a typical graph explaining the change of the coefficient for correct | amending the change of the temperature difference (DELTA) T accompanying the rapid fall of the full charge capacity of a secondary battery, and a full charge capacity. It is a typical graph explaining the correction | amendment style of the full charge capacity of the battery reaction model by the state estimation method of the secondary battery which concerns on another embodiment of this invention. 6 is a schematic graph illustrating a correction mode of a full charge capacity of a battery reaction model by a state estimation method for a secondary battery according to still another embodiment of the present invention.

  As described above, when the accurate full charge capacity of the secondary battery cannot be obtained, the difference between the estimated value and the true value of the secondary battery becomes large, and the secondary battery as described above. There is a possibility that it is difficult to suppress excessive charging / discharging of the battery or to estimate an accurate remaining power amount of the secondary battery.

  The SOC of the secondary battery can be calculated by reflecting the ratio of the integrated value (ΣIΔt) of the current value in the predetermined period Δt to the full charge capacity Qf with respect to the SOC (SOC0) at a specific time point. That is, the SOC of the secondary battery can be expressed by the following formula (2). In this case, the direction in which the current flows during discharging in which the SOC of the secondary battery decreases is the positive direction (that is, the sign of the current is positive).

  For example, a case is assumed where an electric vehicle including an electric motor that generates a driving force by electric power supplied from a secondary battery as a power source is driven in a CD (Charge Depleting) mode. In this case, the SOC of the secondary battery decreases with the passage of time as shown by the solid line shown in FIG. When the full charge capacity of the battery reaction model is correctly estimated, the full charge capacity of the battery reaction model matches the true full charge capacity of the secondary battery, and the SOC estimated using the battery reaction model is also Moreover, it changes similarly to the true SOC represented by the solid line shown in FIG.

  However, when the full charge capacity of the battery reaction model is estimated to be larger than the true full charge capacity of the secondary battery, Qf in the above formula (2) is larger than the true value. As a result, the contribution (decrease in SOC (ΔSOC)) by the second term on the right side of the above equation (2) is reduced, and the SOC is excessively large as represented by the broken line shown in FIG. Presumed. In this case, since the true SOC is smaller than the estimated value, it may be difficult to continue traveling even though it is determined that the electric vehicle can still travel based on the estimated SOC. .

  On the contrary, when the full charge capacity of the battery reaction model is estimated to be less than the true full charge capacity of the secondary battery, Qf in the above formula (2) is smaller than the true value. As a result, the contribution (decrease in SOC (ΔSOC)) by the second term on the right side of the above equation (2) becomes large, and the SOC is too small as shown by the dotted line shown in FIG. Presumed. In this case, the true SOC is larger than the estimated value, and it may be erroneously determined that it is difficult to continue traveling although the electric vehicle is actually still capable of traveling.

  By the way, CS (Charge Sustaining) mode is known as a running mode of an electric vehicle provided with an electric motor that generates a driving force by electric power supplied from a secondary battery as a power source. This CS mode is also referred to as a “charge maintenance mode”, and is adopted in, for example, a PHV that travels in the HV and HV modes. In the CS mode, the vehicle is driven using both an electric motor that operates by electric power and an internal combustion engine that operates by combustion of fuel. As a result, the SOC of the secondary battery is maintained within a predetermined range (for example, 50 to 60%) by charging and discharging, and the running state of the vehicle is suppressed while suppressing deterioration due to excessive charging and discharging of the secondary battery. The state which can respond to the discharge request | requirement and / or charge request | requirement according to can always be maintained. That is, in the CS mode, the SOC of the secondary battery increases due to charging in a certain period.

  In this case, as the secondary battery is charged, the SOC of the secondary battery increases as time passes, as indicated by the solid line shown in FIG. That is, in this case, a current flows in a direction opposite to that during discharging of the secondary battery in the CD mode represented by FIG. 1A described above (the sign of the battery current is reversed). Also in this case, when the full charge capacity of the battery reaction model is correctly estimated, the full charge capacity of the battery reaction model matches the true full charge capacity of the secondary battery, and is estimated using the battery reaction model. The SOC is also changed in the same manner as the true SOC represented by the solid line shown in FIG.

  However, when the full charge capacity of the battery reaction model is estimated to be larger than the true full charge capacity of the secondary battery, Qf in the above formula (2) is larger than the true value. As a result, the contribution (SOC increase (ΔSOC)) due to the second term on the right side of the above equation (2) becomes small, and the SOC becomes too small as shown by the broken line shown in FIG. Presumed. In this case, since the true SOC is larger than the estimated value, the secondary battery is actually charged even though the SOC of the secondary battery has reached the upper limit of the predetermined range, resulting in overcharge. There is a possibility of causing deterioration of the secondary battery.

  On the contrary, when the full charge capacity of the battery reaction model is estimated to be less than the true full charge capacity of the secondary battery, Qf in the above formula (2) is smaller than the true value. As a result, the contribution (increased SOC (ΔSOC)) by the second term on the right side of the above equation (2) becomes large, and the SOC is excessively large as represented by the dotted line shown in FIG. Presumed. In this case, the true SOC is smaller than the estimated value, and actually the secondary battery is stopped charging even though the SOC of the secondary battery has not yet reached the upper limit of the predetermined range. There is a risk that it may be difficult to ensure the amount.

  As described above, the magnitude (absolute value) of the SOC change (ΔSOC) from the SOC (SOC0) at a specific time point is too small when the full charge capacity is estimated to be excessive, and the full charge capacity is If it is underestimated, it will be overestimated. As a result, the SOC in a state in which the SOC decreases due to the discharge of the secondary battery, such as when traveling in the CD mode, is excessive when the full charge capacity is estimated to be excessive, and the full charge capacity is estimated to be too small. If so, each will be underestimated. On the other hand, the SOC in a state where the SOC increases due to the charging of the secondary battery is estimated to be too small when the full charge capacity is estimated to be excessive, and to be excessive when the full charge capacity is estimated to be too small. End up.

  Therefore, in order to accurately estimate the SOC of the secondary battery, it is necessary to acquire an accurate full charge capacity of the secondary battery. Therefore, as described above, an object of the present invention is to provide a technique that makes it possible to accurately estimate the full charge capacity of a secondary battery in a traveling electric vehicle.

  As a result of diligent research to achieve the above object, the present inventor has satisfied the battery reaction model in the process of estimating the SOC of the secondary battery using the battery reaction model as disclosed in Patent Document 2, for example. As the charge capacity deviates from the true full charge capacity of the secondary battery, the estimated value of the internal temperature of the secondary battery calculated in the process becomes (for example, based on a measured value by a temperature sensor or the like) the secondary battery. It has been found that the measured temperature of the external temperature deviates beyond the expected level. In other words, the present inventor is based on the difference between the estimated value Ts of the internal temperature of the secondary battery calculated in the process of estimating the SOC of the secondary battery using the battery reaction model and the measured value T of the external temperature. It has been found that the full charge capacity of the secondary battery can be accurately estimated by correcting the full charge capacity of the battery reaction model, and the present invention has been conceived.

That is, the first embodiment of the present invention is:
A state estimation method for a secondary battery that estimates a full charge capacity and an internal temperature of the secondary battery using a battery reaction model,
Calculate the temperature difference ΔT of the secondary battery from the estimated value Ts of the internal temperature of the secondary battery and the measured value T of the external temperature according to the following formula (1):

When the temperature difference ΔT is larger than a predetermined upper limit Tu, the full charge capacity of the battery reaction model is corrected to a smaller value.
It is a state estimation method of a secondary battery.

  As described above, the secondary battery state estimation method according to the present embodiment is a secondary battery state estimation method that estimates the full charge capacity and internal temperature of the secondary battery using the battery reaction model. Regarding the battery reaction model used in such a state estimation method of the secondary battery and the state estimation method of the secondary battery using the battery reaction model, as described above, for example, Non-Patent Document 1, Patent Document 1, and Various types have been proposed in the prior art including Patent Document 2 and the like.

  For example, a secondary battery state estimation device that performs the secondary battery state estimation method according to the present embodiment includes, for example, a secondary battery, a detection unit, a battery state estimation unit, and a parameter estimation unit. The secondary battery includes, for example, a positive electrode and a negative electrode that include an active material that includes a reaction-participating substance that contributes to an electrochemical reaction, and ions that conduct the ionized reaction-related substance between the positive electrode and the negative electrode. It is a secondary battery provided with a conductor. Specific examples of such secondary batteries include lithium ion batteries. In addition, since the structure of secondary batteries, such as a lithium ion battery, is well-known to those skilled in the art, detailed description in this specification is omitted.

  The detection means detects, for example, the battery voltage, battery current, external temperature, and the like of the secondary battery. The detection means may have any configuration as long as the battery voltage, battery current, and external temperature of the secondary battery can be measured. For example, the detection means may include a voltage sensor, a current sensor, and a temperature sensor.

  The battery state estimation means sequentially calculates the full charge capacity, the charge rate SOC, the open circuit voltage OCV, the battery current I, and the internal temperature of the secondary battery according to the battery model formula based on the detected values of the battery temperature and the battery voltage, for example. presume. The parameter estimation means calculates, for example, an estimation error representing a difference between the detected value and the estimated value of the battery current I based on the detected value and the estimated value of the battery current, and either one of the SOC and the OCV. Based on the estimation error, a predetermined parameter that changes in response to a change in the state of the secondary battery is estimated from the parameter group used in the battery model equation. Further, the battery state estimation means corrects the positive electrode open potential and the negative electrode open potential by reflecting the estimation result of the predetermined parameter by the parameter estimation means in the battery model formula, for example, and corrects the corrected positive electrode open potential and negative electrode open. The OCV is estimated based on the potential.

  The battery state estimation means is a central processing unit (CPU: Central Processing Unit) (e.g., CPU) for executing a predetermined sequence and a predetermined calculation process corresponding to the above estimation process and a full charge capacity correction process described in detail later. A microcomputer or the like, for example, a program corresponding to the predetermined sequence and predetermined arithmetic processing, a detection value based on a detection signal from the detecting means, a result of the arithmetic processing, and the like (for example, RAM ( Random Access Memory (ROM), Read Only Memory (ROM), HDD (Hard Disk Drive), etc.) and data input / output ports for receiving detection signals from the detection means and sending out the results of the above arithmetic processing, etc. List the composition including You can.

  The parameter estimation means may be composed of the above-described calculation means provided individually for the parameter estimation means, or the battery state estimation means or the state estimation of the secondary battery according to this embodiment. An electronic control unit (ECU) or the like included in an apparatus and / or mechanism including a secondary battery as a power source to which the method is applied may function as the parameter estimation unit. Furthermore, the battery state estimation unit and the parameter estimation unit may be distributed and implemented in a plurality of calculation units and / or ECUs.

  The above-described configuration is an example of the configuration of a secondary battery state estimation device that performs the secondary battery state estimation method according to the present embodiment, and the configuration of the secondary battery state estimation device is the above-described configuration. It is not limited. That is, the secondary battery state estimation device that performs the secondary battery state estimation method according to the present embodiment uses the battery reaction model to estimate the internal state of the secondary battery and estimate the SOC. As long as it is a state estimation apparatus, it is not limited to a specific structure.

  By the way, as described above, in order to accurately estimate the SOC of a secondary battery at a specific point in time, it is necessary to obtain an accurate full charge capacity of the secondary battery. Therefore, it is necessary to obtain an accurate open-circuit voltage (OCV) of the secondary battery. In order to obtain the accurate OCV of the secondary battery, it is necessary to obtain the voltage between the terminals of the secondary battery in the fully relaxed state. For example, the secondary battery is in the fully relaxed state such as an electric vehicle that is running. If not, it is difficult to obtain an accurate OCV of the secondary battery.

  When it is difficult to obtain an accurate OCV of the secondary battery as described above, it is conceivable to use an open circuit voltage OCVe estimated using a battery reaction model. However, the OCVe estimated using the battery reaction model may deviate from the true OCV of the secondary battery. For example, as shown in FIG. 2, the correct full charge capacity Qf is estimated based on the correct open-circuit voltage OCV represented by the dashed curve, whereas the solid curve indicates Based on the excessively estimated open circuit voltage OCVe, an excessive full charge capacity Qfe is estimated.

  As described above with reference to FIG. 1, the magnitude (absolute value) of the change in SOC (ΔSOC) from the SOC (SOC0) at a specific time point is too small when the full charge capacity is estimated to be excessive. In addition, when the full charge capacity is estimated to be too small, it is estimated too much. As a result, the SOC in a state where the SOC decreases due to the discharge of the secondary battery is estimated to be excessive when the full charge capacity is estimated to be excessive, and to be excessive when the full charge capacity is estimated to be excessive. Will be. On the other hand, the SOC in a state where the SOC increases due to the charging of the secondary battery is estimated to be too small when the full charge capacity is estimated to be excessive, and to be excessive when the full charge capacity is estimated to be too small. End up.

  By the way, when estimating the internal temperature of the battery from the battery voltage V and the battery current I measured by the detecting means as described in Patent Document 2, for example, the calorific value of the battery calculated in the process is expressed by the following formula ( Calculated according to 3).

  Therefore, as shown in FIG. 3A, when the open-circuit voltage OCVe (thick solid line) estimated using the battery reaction model matches the true open-circuit voltage OCV of the secondary battery, ΔVe (= OCVe −V) = ΔV (= OCV−V). As a result, the heat generation amount We calculated based on the open circuit voltage estimated value OCVe and the heat generation amount W calculated based on the open circuit voltage true value OCV should match. In other words, when the full charge capacity Qfe of the battery reaction model matches the true full charge capacity Qf of the secondary battery, ΔVe = ΔV, and the heat generation amount We (= ΔVe × I) of the secondary battery is The true value W (= ΔV × I) matches, and as a result, a range in which a difference between the estimated value Ts of the internal temperature of the secondary battery and the measured value T of the external temperature is assumed (that is, a temperature assumed in advance). It should be within the maximum distribution).

  However, as described above, the OCVe estimated using the battery reaction model deviates from the true OCV of the secondary battery, and the full charge capacity Qfe of the battery reaction model deviates from the true full charge capacity Qf of the secondary battery. There is a case. In this case, since ΔVe ≠ ΔV and We ≠ W, the estimated value Ts of the internal temperature of the secondary battery and the actually measured value T of the external temperature deviate beyond an assumed level (that is, actual temperature distribution). To do.

  For example, as shown in FIG. 3B, when the estimated open circuit voltage OCVe (thick solid line) is estimated to be larger than the true open circuit voltage OCV (dotted line), as described above, The estimated value Qfe of the charge capacity is estimated to be larger than the true value Qf. In this case, since ΔVe> ΔV and We> W, the range in which the difference between the estimated value Ts of the internal temperature of the secondary battery and the measured value T of the external temperature is assumed (that is, the temperature distribution assumed in advance). Less than the maximum value).

  As described above, the state where the estimated value Ts of the internal temperature of the secondary battery and the actually measured value T of the external temperature deviate beyond an assumed level (that is, the actual temperature distribution) is an estimation of the full charge capacity. It means that the value Qfe is deviated from the true value Qf. Therefore, even if the state estimation of the secondary battery using the battery reaction model is performed as it is, it is difficult to accurately estimate the SOC of the secondary battery. As a result, as described above, it is difficult to suppress excessive charge / discharge of the secondary battery to prevent the battery performance from deteriorating or to estimate the accurate remaining power amount of the secondary battery. .

  Therefore, in the state estimation method of the secondary battery according to this embodiment, the full charge capacity of the battery reaction model is corrected according to the difference between the estimated value Ts of the internal temperature of the secondary battery and the measured value T of the external temperature. By doing so, the full charge capacity of the secondary battery is accurately estimated.

Specifically, in the secondary battery state estimation method according to the present embodiment, as described above,
A temperature difference ΔT of the secondary battery is calculated from the estimated value Ts of the internal temperature of the secondary battery and the measured value T of the external temperature according to the following equation (1).

  By the way, the estimated value Ts of the internal temperature of the secondary battery estimated using the battery reaction model can be calculated using, for example, a thermal diffusion equation. Specifically, the estimated value Ts (t + Δt) of the internal temperature of the secondary battery at the time t + Δt is the estimated value Ts (t) of the internal temperature of the secondary battery at the time t, the measured value T (t) of the external temperature, And the calorific value W (t), it is calculated according to the following equation (4) In the following formula, α and β are coefficients.

  The temperature difference ΔT, which is the difference between the estimated value Ts of the internal temperature of the secondary battery calculated as described above and the actual measured value T of the external temperature measured by a detecting means such as a temperature sensor, is given by the above formula (1 ). If this temperature difference ΔT is larger than the assumed range (that is, not more than the maximum value of the assumed temperature distribution), it means that the full charge capacity of the secondary battery is excessively estimated.

Next, in the secondary battery state estimation method according to the present embodiment, as described above,
When the temperature difference ΔT is larger than a predetermined upper limit value Tu, the full charge capacity of the battery reaction model is corrected to a smaller value. This upper limit value Tu is determined based on the “maximum value of temperature distribution assumed in advance” between the internal temperature and the external temperature of the secondary battery.

  Specifically, as described above, the actual measurement value T of the external temperature of the secondary battery is measured by detection means such as a temperature sensor, for example. Thus, there is a difference (temperature distribution) between the external temperature of the secondary battery measured by the detecting means arranged on the surface of the secondary battery and the internal temperature of the secondary battery that generates heat during charging and discharging. ) Occurs. Such a temperature distribution can be obtained, for example, by an experiment using a test battery in which detection means are provided on the surface and inside of the secondary battery, or by simulation. Based on the maximum value of the temperature distribution thus obtained, the upper limit Tu of the temperature difference ΔT can be determined as appropriate.

  In addition, the upper limit value Tu is, for example, the estimated accuracy of SOC required in the use of the secondary battery, the fluctuation range of the estimated value Ts of the internal temperature of the secondary battery, and the external temperature of the secondary battery. Fine adjustment can be performed as appropriate, for example, by adding an allowable range according to the fluctuation range of the detection value T.

  The specific method for correcting the full charge capacity of the battery reaction model is not particularly limited. For example, the coefficient multiplied by the full charge capacity of the battery reaction model is increased or decreased, or the capacity of the battery reaction model is maintained. The full charge capacity of the battery reaction model can be corrected by increasing or decreasing the magnitude of the coefficient multiplied by the rate.

  The predetermined sequence corresponding to the secondary battery state estimation method according to the present embodiment and the time interval for executing the predetermined calculation process are obtained by the state estimation by the secondary battery state estimation method according to the present embodiment. It can be appropriately adjusted according to the estimation accuracy. For example, as the time interval becomes shorter, the temperature difference ΔT becomes smaller and the estimation accuracy decreases. On the other hand, as the time interval becomes longer, the calculation frequency of the temperature difference ΔT decreases, and the correction frequency of the full charge capacity decreases. Therefore, it is desirable to determine the specific length of the time interval in consideration of, for example, the balance between the required estimation accuracy and the full charge capacity correction frequency.

  Here, the correction procedure of the full charge capacity of the battery reaction model used in the method for estimating the state of the secondary battery according to the present embodiment will be described in detail below with reference to the accompanying drawings. FIG. 4 is a schematic graph illustrating the procedure for correcting the full charge capacity of the battery reaction model used in the secondary battery state estimation method according to one embodiment of the present invention, as described above. In this example, the full charge capacity of the battery reaction model is corrected by increasing or decreasing the coefficient multiplied by the capacity maintenance rate of the battery reaction model. The initial value of the coefficient is 1.

  Specifically, in the example shown in FIG. 4, a temperature difference ΔT that is a difference between the estimated value Ts of the internal temperature of the secondary battery and the measured value T of the external temperature is predetermined after time ta. It is larger than the upper limit Tu. This indicates that the full charge capacity of the battery reaction model is overestimated with respect to the true full charge capacity of the secondary battery. Therefore, in this case, the coefficient multiplied by the capacity retention rate of the battery reaction model is changed to a smaller value, and the full charge capacity of the battery reaction model is corrected to a smaller value. That is, the full charge capacity of the battery reaction model is brought close to a true value.

  As described above, when the full charge capacity of the battery reaction model approaches a true value, the temperature difference ΔT becomes equal to or less than the threshold value (that is, the upper limit value Tu). As a result, the full charge capacity of the battery reaction model is not corrected. Note that it is desirable to adjust the set value of the coefficient so that the correction amount of the full charge capacity of the battery reaction model does not become excessive.

  As described above, according to the state estimation method of the secondary battery according to the present embodiment, the estimated value Ts of the internal temperature of the secondary battery and the actual measurement of the external temperature even in a situation where it is difficult to obtain an accurate OCV. The full charge capacity of the battery reaction model is corrected based on the temperature difference ΔT, which is the difference from the value T, and approaches the true full charge capacity of the secondary battery. As a result, for example, since the SOC of the secondary battery can be accurately estimated, the deterioration of the battery performance by suppressing the excessive charge / discharge of the secondary battery and / or the accurate estimation of the remaining electric energy of the secondary battery are possible. Can be performed more reliably.

  By the way, the calculation of the temperature difference ΔT uses the external temperature T of the secondary battery measured by the detection means, as shown in the above-described equation (1). In addition, in calculating the calorific value We, the battery voltage V and battery current of the secondary battery measured by the detection means (voltage sensor and current sensor) as shown in the above-described equation (3). I is used. When measurement errors are included in the measured values of the external temperature T, battery voltage V, and battery current I of the secondary battery measured by these detection means, the temperature difference ΔT cannot be accurately calculated due to the accumulation of these measurement errors. There is a fear.

  Here, the influence on the correction of the full charge capacity due to the accumulation of measurement errors of the respective detection means of the external temperature T, the battery voltage V, and the battery current I of the secondary battery will be described with reference to the accompanying drawings. . FIG. 5 is a schematic diagram for explaining the influence on the correction of the full charge capacity due to the accumulation of measurement errors of the measurement values of the means for detecting the external temperature T, the battery voltage V, and the battery current I of the secondary battery as described above. It is a simple graph. More specifically, FIG. 5 shows a case where the temperature difference ΔT increases with time.

  The dotted curve shown in FIG. 5 represents the temporal transition of the temperature difference ΔT when the measurement error does not affect the measured value T, the battery voltage V, and the battery current I of the external temperature of the secondary battery. In this case, similarly to the example shown in FIG. 4 described above, the temperature difference ΔT is larger than the predetermined upper limit value Tu at time ta. A solid curve represents a temporal transition of the temperature difference ΔT when a measurement error affects the measured value T, the battery voltage V, and the battery current I of the external temperature of the secondary battery in a subtractive manner. In this case, since the value of the second term on the right side of the above-described equation (1) becomes small, the temperature difference ΔT is calculated excessively. As a result, at time ta ′ earlier than time ta, temperature difference ΔT is larger than a predetermined upper limit value Tu. Conversely, the dashed curve represents the temporal transition of the temperature difference ΔT when the measurement error additionally affects the measured value T, the battery voltage V, and the battery current I of the external temperature of the secondary battery. In this case, since the value of the second term on the right side of Equation (1) is increased, the temperature difference ΔT is calculated too small. As a result, even after the time ta, the temperature difference ΔT is not larger than the predetermined upper limit value Tu.

  As described above, when the temperature difference ΔT is not accurately calculated due to the measurement error of the measured value T, the battery voltage V, and the battery current I of the external temperature of the secondary battery, the full charge capacity of the battery reaction model is corrected. There is a possibility that the timing to be deviated from the original timing or the full charge capacity of the battery reaction model is not corrected. Therefore, in the method for estimating the state of the secondary battery according to the present invention, the full charge capacity of the secondary battery can be reduced by preventing the full charge capacity of the battery reaction model from being erroneously corrected based on the inaccurate temperature difference ΔT. In order to estimate accurately, it is desirable to consider the influence of accumulation of measurement errors of the measured value T of the external temperature of the secondary battery, the battery voltage V, and the battery current I.

  Therefore, the present inventor, as a measure corresponding to the magnitude of the influence of the measurement error, the temperature difference caused by the accumulation of the measurement value T of the external temperature of the secondary battery, the battery voltage V, and the measurement error of the battery current I. An error range Et of ΔT was adopted. This error range Et is a temperature when the measurement error of the actual measurement value T of the external temperature of the secondary battery acts in a subtractive manner and the estimated value We of the heat generation amount becomes small due to the measurement error of the battery voltage V and the battery current I. The difference ΔT (solid line in FIG. 5) and the measurement error of the actual measurement value T of the external temperature of the secondary battery act in addition, and the estimated value We of the heat generation amount increases due to the measurement error of the battery voltage V and the battery current I. And a temperature difference ΔT (broken line in FIG. 5). In FIG. 5, the error range Et is represented by a vertical double arrow. When the error range Et exceeds a predetermined threshold value, there is a high possibility that the temperature difference ΔT is not accurately calculated as described above. Therefore, in this case, by prohibiting the correction of the full charge capacity, it is possible to prevent the full charge capacity of the battery reaction model from being erroneously corrected based on the inaccurate temperature difference ΔT.

That is, the second embodiment of the present invention is:
A method for estimating a state of a secondary battery according to the first embodiment of the present invention, comprising:
The error range Et of the temperature difference ΔT caused by the measurement errors ΔMt, ΔMv, and ΔMi of the respective detection means for measuring the actual measured value T, the battery voltage V, and the battery current I of the external temperature of the secondary battery is expressed by the following equation: Calculate according to (5),

In the above equation, Ts ′ and Ts ″ represent estimated values Ts of the internal temperature of the secondary battery when the measurement error ΔMt acts additively and subtractively, respectively, and W ₊ and W ₋ represent the secondary The estimated value We when the ΔMv and ΔMi act so that the estimated value We of the heat generation amount of the battery is large and small,
When the error range Et is larger than a predetermined upper limit Te, the correction of the full charge capacity is prohibited.
It is a state estimation method of a secondary battery.

  As described above, the first term on the right side of the equation (5) indicates that the measurement error of the actual measurement value T of the external temperature of the secondary battery acts as a subtraction, and the amount of heat generated by the measurement error of the battery voltage V and battery current I. This corresponds to an excessive temperature difference ΔT calculated when the estimated value We is small (solid line in FIG. 5). On the other hand, the second term on the right side of Equation (5) is an estimated value of the amount of heat generated by the measurement error of the actual measurement value T of the external temperature of the secondary battery and the measurement error of the battery voltage V and the battery current I. This corresponds to an excessive temperature difference ΔT calculated when We increases (broken line in FIG. 5). Therefore, the error range Et calculated according to the above equation (5) is the measurement error ΔMt, ΔMv of each detection means for measuring the actual measured value T, the battery voltage V, and the battery current I of the external temperature of the secondary battery, and It can be said that it corresponds to the fluctuation range of the temperature difference ΔT caused by ΔMi (double arrow in FIG. 5).

  The large error range Et means that the fluctuation range of the temperature difference ΔT due to the measurement error of the measured value T, the battery voltage V, and the battery current I of the external temperature of the secondary battery is large. That is, when the error range Et is larger than a predetermined threshold, it is difficult to accurately calculate the temperature difference ΔT, and the full charge capacity of the battery reaction model can be appropriately corrected based on the temperature difference ΔT. Have difficulty. Therefore, in the secondary battery state estimation method according to the present embodiment, in such a case, the correction of the full charge capacity is prohibited. Thereby, it is possible to prevent the full charge capacity of the battery reaction model from being erroneously corrected based on the inaccurate temperature difference ΔT.

  Note that the measurement errors ΔMt, ΔMv, and ΔMi can be appropriately determined based on the measurement errors of the respective detection means (temperature sensor, voltage sensor, and current sensor, respectively) that are measured in advance by experiments or the like. The measurement errors ΔMt, ΔMv, and ΔMi may be the maximum value of the measurement errors of the respective detection means measured in this way, or may be an average value. Further, the upper limit value Te can be appropriately determined according to the magnitudes of the measurement errors ΔMt, ΔMv, and ΔMi determined as described above.

  However, when an excessively large value is set as the upper limit value Te, the battery reaction is based on the temperature difference ΔT that fluctuates due to the measured value T of the external temperature of the secondary battery, the battery voltage V, and the measurement error of the battery current I. There is an increased risk that the full charge capacity of the model will be erroneously corrected. Conversely, when an excessively small value is set as the upper limit value Te, the correction of the full charge capacity is frequently prohibited, and the effect of improving the accuracy of state estimation by the state estimation method for the secondary battery according to the present embodiment is sufficiently achieved. There is an increased risk that it will be difficult to achieve this. As described above, the upper limit value Te is a state associated with a decrease in accuracy of state estimation caused by measurement errors of the external temperature T of the secondary battery, the battery voltage V, and the battery current I, and the prohibition of the correction of the full charge capacity. For example, a range in which the estimation accuracy can be appropriately balanced can be appropriately determined by obtaining a range in which the estimation accuracy can be balanced appropriately by, for example, a model experiment.

  By the way, for example, in a secondary battery constituted by a plurality of single cells connected in parallel, as shown by a portion surrounded by a dotted line in FIG. In some cases, the fuse of any single battery is disconnected, and the full charge capacity of the entire secondary battery is drastically reduced. In addition, as shown in FIG. 6B, when the active material constituting the battery electrode is lost due to, for example, a high load or an impact, the full charge capacity of the secondary battery is drastically reduced. There is also.

  As described above, when the full charge capacity of the secondary battery rapidly decreases, the charge capacity (remaining power amount) of the secondary battery also decreases rapidly. Therefore, if the secondary battery continues to be used without correcting the full charge capacity of the battery reaction model in response to the decrease in the full charge capacity as described above, the battery performance due to excessive charge / discharge of the secondary battery is reduced. There is a possibility that deterioration may be caused or it may be difficult to estimate an accurate remaining power amount of the secondary battery. Therefore, when the full charge capacity of the secondary battery rapidly decreases as described above, it is desirable to correspondingly decrease the capacity retention rate of the battery reaction model.

  Note that when the full charge capacity of the secondary battery rapidly decreases, the measured value V of the battery voltage also rapidly decreases. On the other hand, the estimated value of the OCV of the secondary battery does not decrease with the sudden decrease in the full charge capacity of the secondary battery as described above, so the amount of heat generation increases rapidly and the estimated value of the internal temperature of the secondary battery. The temperature difference ΔT, which is the difference between Ts and the actual measured value T of the external temperature, will increase rapidly. Thus, when the full charge capacity of the secondary battery changes abruptly, the temperature difference ΔT also changes abruptly. Therefore, by rapidly changing the capacity retention rate of the battery reaction model when the temperature difference ΔT changes rapidly, the battery performance may be deteriorated due to excessive charging / discharging of the secondary battery, The possibility that it may be difficult to estimate the remaining power amount can be reduced.

That is, the third embodiment of the present invention
A method for estimating a state of a secondary battery according to the first embodiment of the present invention, comprising:
When the deviation Dt between the previous calculated value and the current calculated value of the temperature difference ΔT is larger than a predetermined upper limit value Tk, the capacity retention rate k of the battery reaction model is a value less than a predetermined value of 1 set to kf,
It is a state estimation method of a secondary battery.

  As described above, in the secondary battery state estimation method according to the present embodiment, when the deviation Dt between the previous calculated value of the temperature difference ΔT and the current calculated value is larger than the predetermined upper limit value Tk, The capacity retention rate k of the battery reaction model is set to a predetermined value kf less than 1. For example, as shown in the upper graph of FIG. 7, when the temperature difference ΔT suddenly increases at time tc, a deviation Dt between the previous calculated value and the current calculated value of the temperature difference ΔT is determined in advance. When the value is larger than the upper limit value Tk, the capacity retention rate k of the battery reaction model is set to a value kf less than a predetermined value 1 as shown in the lower graph of FIG. As a result, it is possible to reduce the possibility that battery performance will be deteriorated due to excessive charging / discharging of the secondary battery, and that it is difficult to estimate the accurate remaining power amount of the secondary battery.

  From the viewpoint of reducing the risk of battery performance deterioration due to excessive charging / discharging of the secondary battery or difficulty in estimating the accurate remaining power amount of the secondary battery, the battery reaction model It is desirable to set the capacity maintenance rate k to a predetermined value kf less than 1 as quickly as possible. For example, the change of the value of the capacity maintenance rate k to the value kf may be changed discontinuously as shown in the lower graph of FIG. 7 instead of gradually changing.

  The upper limit value Tk can be determined as appropriate in consideration of, for example, a reduction factor of the full charge capacity assumed in the configuration of the secondary battery, a fluctuation range of the full charge capacity accompanying normal use, and the like. As described above, as the reduction factor, as described above, for example, in the secondary battery constituted by a plurality of single cells connected in parallel, the disconnection of the fuse of any single cell and the electrode active material due to, for example, high load and impact Omissions can be mentioned. Further, the fluctuation range of the full charge capacity associated with the normal use of the secondary battery can be measured or estimated by, for example, a model experiment or the like that reproduces the environment and usage situation assumed in the application of the secondary battery.

  Further, as described above, kf, which is a set value of the capacity maintenance rate k when the deviation is larger than the upper limit value Tk, is a value less than 1 determined in advance. The specific value of kf reduces the possibility that the battery performance will be deteriorated due to excessive charging / discharging of the secondary battery, and that it is difficult to estimate the accurate remaining power amount of the secondary battery. Should be small enough so that is possible. That is, the specific value of kf is preferably determined based on a fail safe design philosophy that avoids such unintended and undesirable situations.

  In the secondary battery state estimation method according to this embodiment, as described above, the capacity retention rate of the battery reaction model is based on the deviation Dt between the previous calculated value and the current calculated value of the temperature difference ΔT. k is set to a predetermined value kf less than 1. However, in a broad sense, this embodiment broadly sets the capacity retention rate k of the battery reaction model to a predetermined value kf less than 1 when the full charge capacity of the secondary battery changes abruptly, This reduces the possibility that battery performance will be deteriorated due to excessive charging / discharging of the secondary battery, and that it is difficult to estimate the accurate remaining power amount of the secondary battery. Therefore, the criterion for determining whether or not to change the capacity retention rate k of the battery reaction model as described above is not limited to the deviation Dt. Specifically, for example, based on the temporal change rate of the temperature difference ΔT (the change amount of the temperature difference ΔT per unit time), whether or not to change the capacity retention rate k of the battery reaction model as described above is determined. You may judge.

  By the way, the SOC control according to various situations, such as a use period of a secondary battery, the travel mode of an electric vehicle, is applied to the secondary battery mounted as a power supply in the electric vehicle provided with the electric motor as a power source. For example, when the main purpose is to suppress deterioration due to excessive charge / discharge of the secondary battery, the SOC of the secondary battery is controlled to be maintained within a predetermined range. For this purpose, it is necessary to accurately estimate the SOC at that time by appropriately reflecting the increase / decrease in the SOC accompanying the use of the secondary battery.

  On the other hand, as described above with reference to Expression (2), the SOC of the secondary battery is a fully charged current value integrated value (ΣIΔt) in a predetermined period Δt with respect to SOC (SOC0) at a specific time point. It can be calculated by reflecting the ratio to the capacity Qf. Therefore, the magnitude (absolute value) of the change in SOC (ΔSOC) from the SOC (SOC0) at a specific time point is estimated to be too small when the full charge capacity is estimated to be excessive. In this case, the increase / decrease in the SOC accompanying the use of the secondary battery is calculated too small, and it is difficult to accurately estimate the SOC at that time.

  However, according to the state estimation method of the secondary battery according to the present invention, the full charge capacity of the battery reaction model depends on the temperature difference ΔT between the estimated value Ts of the internal temperature of the secondary battery and the measured value T of the external temperature. It is corrected. Therefore, the increase / decrease in the SOC accompanying the use of the secondary battery is appropriately reflected, and the SOC at that time is accurately estimated. As a result, the SOC of the secondary battery can be maintained within a predetermined range, and control for suppressing deterioration due to excessive charging / discharging of the secondary battery can be accurately performed.

  In the above, in order to prevent the increase / decrease in SOC due to the use of the secondary battery from being excessively reduced and as a result, the possibility of deterioration due to excessive charge / discharge of the secondary battery is increased, the full charge capacity It is desirable to keep the possibility of overestimation as low as possible. That is, it is desirable to keep the temperature difference ΔT as small as possible even in the control for keeping the temperature difference ΔT within a predetermined upper limit value Tu or less by the state estimation method of the secondary battery according to the present invention.

  Specifically, when the temperature difference ΔT is larger than the upper limit value, the change in the full charge capacity when the full charge capacity of the battery reaction model is corrected to a smaller value is made rapid, while the full charge capacity is corrected after the correction. It is desirable to slow the change in full charge capacity when returning to a larger value.

That is, the fourth embodiment of the present invention is
A method for estimating a state of a secondary battery according to the first embodiment of the present invention, comprising:
When the temperature difference ΔT is larger than the upper limit value Tu, a capacity change rate that is an absolute value of a change amount of the full charge capacity per unit time when the full charge capacity of the battery reaction model is corrected to a smaller value. Vud is then set to a value greater than the capacity change rate Vuu, which is the absolute value of the amount of change in full charge capacity per unit time when the full charge capacity of the battery reaction model is returned to a larger value.
It is a state estimation method of a secondary battery.

  Here, the above will be described in detail below with reference to the accompanying drawings. FIG. 8 shows the battery when the temperature difference ΔT exceeds the upper limit Tu when the main purpose is to suppress the deterioration of the secondary battery to which the secondary battery state estimation method according to this embodiment is applied. Represents the correction mode of the full charge capacity of the reaction model.

  In the example shown in FIG. 8, the temperature difference ΔT exceeds the upper limit value Tu at time ta. That is, the full charge capacity of the battery reaction model is estimated excessively. In this case, as described above, the increase / decrease in the SOC due to the use of the secondary battery is excessively calculated, and it is difficult to accurately estimate the SOC at that time. More specifically, as described above with reference to FIG. 1, both the decrease width associated with the discharge of the SOC of the secondary battery and the increase width associated with the charge are calculated to be too small. As a result, even if the SOC is within a preferred range on the model, the true SOC may deviate from the preferred range and cause battery deterioration due to excessive charge / discharge. Therefore, after the time ta, for example, the full charge capacity of the battery reaction model is corrected rapidly (rapidly) to a smaller value by rapidly correcting the capacity maintenance rate to a smaller value (capacity change rate Vud). ). Thereby, the possibility of causing deterioration of the battery due to excessive charge / discharge as described above can be reduced.

  Thereafter, the increase in temperature difference ΔT stops at time tb. In FIG. 8, after time tb, the full charge capacity of the battery reaction model is not further reduced (corrected) and maintained at a constant value. After the time tb, the temperature difference ΔT starts to decrease, and at the time tc, the temperature difference ΔT again falls below the upper limit value Tu. That is, the full charge capacity of the battery reaction model is appropriately estimated. Therefore, after time tc, the full charge capacity of the battery reaction model is returned to a larger value so that the temperature difference ΔT does not decrease excessively. However, returning the full charge capacity of the battery reaction model to a larger value at this stage may lead to estimation of an excessive full charge capacity again. Therefore, after time tc, the full charge capacity of the battery reaction model is gradually (gradually) corrected to a larger value (capacity change speed Vuu). With such a battery charge model correction mode for full charge capacity (capacity change speed Vud> capacity change speed Vuu), the possibility of battery deterioration due to overdischarge as described above can be reduced.

  As described above, the SOC control whose main purpose is to suppress the deterioration caused by the excessive charge / discharge of the secondary battery has been described. However, there may be a case where the SOC control in the electric vehicle is mainly intended to “ensure as much discharge amount as possible and achieve as long a travel distance as possible”.

  In this case as well, it is desirable to accurately estimate the SOC by appropriately correcting the full charge capacity of the battery reaction model. However, from the viewpoint of securing as much discharge amount as possible and achieving the longest possible travel distance, the SOC reduction width (ΔSOC) accompanying discharge is excessively estimated and the SOC of the secondary battery is excessively estimated. It is desirable to reduce as much as possible. That is, it is desirable to perform correction for increasing the full charge capacity of the battery reaction model quickly and correction for reducing the full charge capacity of the battery reaction model slowly.

That is, the fifth embodiment of the present invention
A method for estimating a state of a secondary battery according to the first embodiment of the present invention, comprising:
When the temperature difference ΔT is larger than the upper limit value Tu, a capacity change rate that is an absolute value of a change amount of the full charge capacity per unit time when the full charge capacity of the battery reaction model is corrected to a smaller value. Vud is then set to a value smaller than the capacity change rate Vuu, which is the absolute value of the change amount of the full charge capacity per unit time when the full charge capacity of the battery reaction model is returned to a larger value.
It is a state estimation method of a secondary battery.

  Here, the above will be described in detail below with reference to the accompanying drawings. FIG. 9 shows the temperature when the main purpose is to secure as much discharge as possible of the secondary battery to which the state estimation method of the secondary battery according to this embodiment is applied and to achieve the longest possible travel distance. This represents a correction mode of the full charge capacity of the battery reaction model when the difference ΔT exceeds the upper limit Tu. The definition of the capacity change speeds Vud and Vuu is the same as in FIG.

  In the example shown in FIG. 9, the temperature difference ΔT exceeds the upper limit value Tu at time ta. That is, the full charge capacity of the battery reaction model is estimated excessively. In the present embodiment, the SOC control is mainly intended to secure as much discharge amount as possible and achieve the longest possible travel distance. Therefore, the SOC of the secondary battery is in a state of decreasing with discharge. At this time, if the full charge capacity of the battery reaction model is estimated to be excessive as described above, the SOC decrease width (ΔSOC) is calculated to be excessively small as described above, and the SOC is excessively estimated. Therefore, according to the SOC control based on the excessively estimated SOC as described above, even if the SOC is within a preferable range on the model, the true SOC is below the lower limit of the preferable range and is caused by overdischarge. There is a risk of battery deterioration. Therefore, it is necessary to correct the full charge capacity of the battery reaction model to a smaller value.

  However, if this correction is performed rapidly (promptly), the SOC on the model is presumed to be too small, and the discharge of the secondary battery is excessively limited. For example, it may be difficult to ensure the travel distance of the electric vehicle. is there. Therefore, after time ta, for example, the full charge capacity of the battery reaction model is gradually (gradually) corrected to a smaller value by gradually correcting the capacity maintenance ratio to a smaller value (capacity change speed Vud). ). Thereby, possibility that discharge of a secondary battery will be restrict | limited excessively as mentioned above can be reduced.

  Thereafter, the increase in temperature difference ΔT stops at time tb. In FIG. 9, after time tb, the full charge capacity of the battery reaction model is not further reduced (corrected) and maintained at a constant value. After the time tb, the temperature difference ΔT starts to decrease, and at the time tc, the temperature difference ΔT again falls below the upper limit value Tu. That is, the full charge capacity of the battery reaction model is appropriately estimated. Therefore, after time tc, the full charge capacity of the battery reaction model is returned to a larger value so that the temperature difference ΔT does not decrease excessively. At this time, it is desirable to quickly return the full charge capacity to a larger value from the viewpoint of securing as much discharge amount as possible and achieving the longest possible travel distance. Therefore, after time tc, the full charge capacity of the battery reaction model is corrected rapidly (rapidly) to a larger value (capacity change speed Vuu). With such a battery charge model full charge capacity correction mode (capacity change speed Vud <capacity change speed Vuu), it is possible to secure as much discharge as possible and achieve as long a travel distance as possible.

  Although several embodiments having specific configurations have been described above for the purpose of illustrating the present invention, the scope of the present invention is not limited to these exemplary embodiments, and patents Needless to say, modifications can be made as appropriate within the scope of the claims and the description of the specification.

Claims (1)

A state estimation method for a secondary battery that estimates a full charge capacity and an internal temperature of the secondary battery using a battery reaction model,
Calculate the temperature difference ΔT of the secondary battery from the estimated value Ts of the internal temperature of the secondary battery and the measured value T of the external temperature according to the following formula (1):

When the temperature difference ΔT is larger than a predetermined upper limit Tu, the full charge capacity of the battery reaction model is corrected to a smaller value.
Secondary battery state estimation method.

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