JP2010190818A - Method for detecting state of power storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detecting a state of a power storage device for accurately evaluating radiation power of the power storage device accompanied by a reaction process of different speeds. <P>SOLUTION: The method for detecting a state of the power storage device of a first embodiment compares a voltage V<SB>DE</SB>in discharge end or a voltage V<SB>CE</SB>in charge end with a reference value V<SP>ref</SP>in step S4 to determine that power capability COD is insufficient when being lower than the reference value V<SP>ref</SP>, optimizes a relaxation function F(t) by using ΔV(t) calculated in step S8 in step S9, in addition estimates a prescribed state amount S by using the relaxation function F(t) optimized in step S10, and further compares the estimated state amount S with a reference value S<SP>ref</SP>in step S11 to determine that COD is secured when the state amount S satisfies a prescribed condition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for detecting the state of an electricity storage device, and more particularly to a method for detecting the discharge capability of an electricity storage device.

  In recent years, expectations for users of power storage devices have increased. For example, electric devices are often used for driving a car, and the importance of in-vehicle power sources is increasing. In the past, more than 20 to 30 years, the demand for on-vehicle power supply was limited to functions such as engine start, air conditioner, and lamp lighting. On the other hand, in recent years, by-wire has progressed, and safety-related parts represented by electric brakes (EPB) have been controlled electrically. In addition, with energy saving and carbon dioxide emission regulations, as a measure for improving fuel efficiency, it is required to secure an idling stop function and a restarting ability at a short stop such as an intersection.

  In addition, as a backup power source and power leveling, there is a demand for performance that is inexpensive, low in maintenance cost, and can ensure reliability. Furthermore, with the widespread use of mobile devices, ubiquitous power storage devices have been screamed, while accidents associated with battery-related heat generation and failures have been reported, making life diagnosis and ensuring reliability essential. It is coming. Thus, various functions are required for the power supply and the battery, and it is desired to improve these problems by improving the battery state detection accuracy correspondingly.

  In general, under a sufficiently stable condition after charging and discharging of an electricity storage device, the open-circuit voltage (OCV) and the remaining capacity (SOC: State of charge) have a relationship corresponding to 1: 1 (FIG. 12). 81). However, the storage device after charging and discharging is, for example, in the case of a storage battery containing an electrolytic solution, the ion generation / extinction reaction on the electrode plate surface by an electrochemical reaction, and the movement of ions by diffusion and convection of the electrolytic solution, Are influenced by each. Such an effect always occurs in a storage battery in which ions move in an electrolyte solution such as a Li ion battery or a lead storage battery. Even in the case of a capacitor, when an electrolytic solution is used as a storage medium, the concentration of the medium changes, so that it is also affected by ion diffusion and the like.

  Even when a solid electrolyte is used as a medium instead of the electrolytic solution, ions in the electrolyte are biased due to a power storage action. Therefore, since it takes time to reach a stable state depending on the medium or the medium, a convergence time corresponding to the characteristics of each power storage device is required until a stable OCV is obtained (for example, a liquid lead acid battery). In the case of about 20 hours).

  When there is a change over time in the ion concentration in such an electrolyte or electrolyte, it takes a long time until the ion concentration becomes completely homogeneous, and the battery voltage measurement results within a finite measurement time Then, the 1: 1 relationship between OCV and SOC is lost. FIGS. 13 and 14 are diagrams illustrating an example of a change with time of the OCV when the SOC and temperature of the storage battery are constant. FIG. 13 shows that even if the SOC is constant, it takes time for the OCV (reference numeral 82) to stabilize at a constant value. FIG. 14 shows the change in OCV (reference numerals 83, 84, 85) in storage batteries having different SOH (degradation level, state of health), but the SOC and temperature are adjusted to the same conditions, and the most recent charge / discharge conditions are also set. Even if they are the same, if the SOH is different, it does not converge to the same OCV.

  As described above, in the state detection method for obtaining the SOC from the OCV, the influence of the SOH is not reflected by simply estimating and using the OCV or using the latest charge / discharge history. If the SOC is obtained from the OCV without reflecting the deterioration condition of the power storage device, there is a problem that the accuracy of state detection is lowered. In addition, when these SOCs and SOH are used, it becomes impossible to accurately determine the COD (discharge capability).

  Patent document 1 is known as an example of a prior art. In this method, as a method for detecting the OCV and SOC of the secondary battery, a transient response corresponding to the charge / discharge history is used to correct the OCV. Here, the transient response changes according to the charge / discharge time, and there is a mention of the resistance component, the polarization component according to the internal reaction of the battery, and the diffusion rate of the electrolytic solution.

Japanese Patent Laid-Open No. 2005-106615

  However, in the detection method described in Patent Document 1, when a short-time transient response is measured by performing a short charge / discharge, it is possible to know the deterioration according to the fast reaction speed inside the battery, but the long-term transient Since the response cannot be measured, the deterioration due to the slow reaction rate cannot be known. In order to measure a long-term transient response, it is necessary to perform charging / discharging for a long time. However, since the SOC changes as the charging / discharging time becomes longer, the subsequent short-term transient response also changes. Thus, with the detection method described in Patent Document 1, it is impossible to detect the state of the storage battery such as the remaining capacity by capturing the deterioration according to the different reaction rates inside the battery.

  In a series of reaction processes, called electrochemical reactions inside the battery, not only the formation and extinction of ions that occur in the vicinity of the electrode plate (fast reaction rate), but also migration (slow reaction rate) by migration and diffusion of ions in the electrolyte. In such a reaction system, reaction processes with different speeds greatly affect the state detection accuracy as an error factor. This means that, even with capacitors and Li-ion batteries, there are differences in the reaction rate and diffusion rate, but charging and discharging are performed through two or more rate-limiting processes of reaction and ion movement in a finite volume. If it is an electricity storage device to perform, the same influence appears.

  Accordingly, the present invention has been made to solve these problems, and an object of the present invention is to provide a state detection method for a power storage device for accurately evaluating the discharge capability of the power storage device with reaction processes having different speeds. And

  A first aspect of the state detection method of the power storage device according to the present invention is a method for detecting the state of the power storage device, wherein the power storage device stops charging / discharging and reaches a state satisfying a predetermined stability condition. When the voltage of the device is a stable voltage at the time of stop, and the amount of change from the stable voltage at the time of stop when the time t has elapsed since the storage device has stopped charging and discharging, A relaxation function F (t) for calculating an amount of change in hourly voltage is created in advance as a function of a predetermined state quantity of the power storage device, and the voltage at the end of charging immediately before stopping the charge of the power storage device or the discharge is stopped Measuring the voltage at the end of discharge immediately before the measurement, measuring the voltage after stopping the charging or discharging of the electricity storage device, calculating the amount of change in voltage at the time of stopping from the voltage measurement value, and calculating the relaxation function F (t , Estimating the state quantity from the optimized relaxation function F (t), and using the discharge end voltage or the charge end voltage and the estimated state quantity to discharge the power storage device It is characterized by determining capability (COD).

  In another aspect of the state detection method for an electricity storage device of the present invention, the relaxation function F (t) is a reaction of 2 or more (assumed to be m) created in advance corresponding to the reaction rate inside the electricity storage device. The rate-dependent relaxation function fi (t) (i = 1 to m) is represented by a linear combination, and the reaction rate-based relaxation function fi (t) (i = 1 to m) is calculated from the voltage measurement value. The amount of change in voltage at the time of stoppage is optimized by being separated into components corresponding to the reaction rate.

  According to another aspect of the state detection method for an electricity storage device of the present invention, when the current due to the charge / discharge is minute or constant and the influence on the transient change inside the electricity storage device is limited within a predetermined range, the electricity storage device Is characterized in that charging / discharging is determined to have been stopped.

  According to another aspect of the method for detecting a state of an electricity storage device of the present invention, a voltage correction amount for correcting a voltage change due to the current is created in advance, and the relaxation is performed using a voltage obtained by adding the voltage correction amount to the voltage measurement value. It is characterized by optimizing the function F (t).

  In another aspect of the method for detecting the state of the electricity storage device of the present invention, the remaining capacity increase / decrease amount (ΔSOC) at the time of charge / discharge stop is calculated from the current integrated value obtained by integrating the current during charge / discharge immediately before the charge / discharge stop. The remaining capacity increase / decrease amount is added to the remaining capacity when charging / discharging is stopped to calculate the remaining capacity (SOC) when charging / discharging is stopped, and the voltage at the end of discharging or the voltage at the end of charging and the relaxation function F ( The COD is determined based on the state quantity estimated from t) and the SOC.

  According to another aspect of the state detection method for a power storage device of the present invention, a charging efficiency calculation formula using a predetermined state quantity and a charging end voltage as variables is created in advance, and the SOC at the time of charge / discharge stop is the relaxation It is calculated by correcting the remaining capacity increase / decrease amount by charging efficiency calculated by substituting the state quantity calculated using the function F (t) and the charging end voltage into the charging efficiency calculation formula. It is characterized by.

  Another aspect of the state detection method for a power storage device according to the present invention is characterized in that the state quantity is a remaining capacity (SOC) of the power storage device.

  Another aspect of the state detection method for a power storage device according to the present invention is characterized in that the state quantity is a degree of deterioration (SOH) of the power storage device.

In another aspect of the state detection method for an electricity storage device according to the present invention, the relaxation function F (t) includes a component f _fast (t) having a fast relaxation rate and a component f _slow (t) having a _slow relaxation rate, and the f _fast (T), f _slow (t) and the ratio f _fast (t) / f _slow (t) of each reference value are created in advance and calculated from the optimized F (t). The COD is determined by using f _fast (t), the f _slow (t), the f _fast (t) / f _slow (t), and the respective reference values.

In another aspect of the state detection method for an electricity storage device according to the present invention, the state quantity is a deterioration degree SOH of the electricity storage device, and the f _fast (t), the f _slow (t), and the f _fast (t ) / F _slow (t) and the respective reference values are used to calculate the degree of deterioration.

In another aspect of the state detection method of the power storage device of the present invention, a fast transient change correction amount calculation formula using the remaining capacity and the voltage at the end of charging as variables is created in advance, and the remaining capacity when the charge / discharge is stopped and the by substituting a charge end voltage to the high speed transient correction value calculation formula to calculate the correction amount with respect to the f _{fast (t),} wherein the deterioration degree by using the corrected the f _{fast (t)} in the correction amount Is calculated.

According to another aspect of the state detection method of the electricity storage device of the present invention, the relaxation function F (t) with respect to the f _fast (t), the f _slow (t), and the f _fast (t) / f _slow (t) A concentration change calculation formula for calculating the concentration change amount of the electrolytic solution of the electricity storage device is created in advance, and the concentration of the electrolyte solution is calculated from the concentration change calculation formula using the optimized relaxation function F (t). A change amount is calculated and used as the state amount.

According to another aspect of the method for detecting the state of an electricity storage device of the present invention, the bias (stratification) change amount of the concentration distribution of the electrolytic solution of the electricity storage device is defined as the stratification change amount, and the f _{fast of the} relaxation function F (t) is determined. (T), a stratification change amount calculation formula for calculating the stratification change amount for the f _slow (t) and the f _fast (t) / f _slow (t) is created in advance, and the optimized The stratification change amount is calculated from the stratification change calculation formula using a relaxation function F (t) and used as the state quantity.

In another aspect of the method for detecting the state of the electricity storage device of the present invention, the amount of change in the concentration distribution bias (lateral stratification) in the lateral direction with respect to the liquid level of the electrolyte solution of the electricity storage device is defined as the amount of lateral stratification change, A lateral stratification change amount calculation for calculating the lateral stratification change amount of the relaxation function F (t) with respect to the f _fast (t), the f _slow (t), and the f _fast (t) / f _slow (t). An equation is created in advance, and the lateral stratification change amount is calculated from the lateral stratification change amount calculation formula using the optimized relaxation function F (t) and used for the state quantity. To do.

In another aspect of the state detection method of the electricity storage device of the present invention, the amount of change in the concentration distribution in the lateral direction and the longitudinal direction (lateral stratification, vertical stratification) with respect to the electrolyte surface of the electricity storage device is calculated. The vertical and horizontal stratification change amount is calculated as the vertical and horizontal stratification change amount with respect to the f _fast (t), the f _slow (t) and the f _fast (t) / f _slow (t) of the relaxation function F (t). A vertical and horizontal stratification variation calculation formula is created in advance, and the horizontal stratification variation and vertical stratification variation are calculated from the vertical and horizontal stratification variation calculation formula using the optimized relaxation function F (t). Is used for the state quantity.

  In another aspect of the state detection method for an electricity storage device according to the present invention, the relaxation function F (t) is further created in advance as a function of the temperature of the electricity storage device, and the relaxation function is measured by measuring the temperature of the electricity storage device. It is used for calculation of F (t).

  According to another aspect of the state detection method of the power storage device of the present invention, the stable voltage at the time of stop is a stable OCV, and the stable OCV calculated from a stable OCV calculation formula created in advance is calculated from the measured voltage value. The OCV change amount is calculated by subtraction, and the OCV change amount is set as the stop-time voltage change amount.

  In another aspect of the state detection method for an electricity storage device of the present invention, the state quantity is calculated by estimating the state quantity for each reaction rate from the relaxation function fi (t) for each reaction rate, and summing the state quantities. It is characterized by.

According to another aspect of the state detection method for an electricity storage device of the present invention, the relaxation function fi (t) for each reaction rate in a predetermined state, the SOC, and the SOH for each reaction rate are respectively fi ^ref (t) and SOC ^ref , And SOHi ^ref , and the dependence on the temperature T of the electricity storage device is g (T), the relaxation function for each reaction rate fi ⁿ (t) after the completion of the nth charge / discharge is
fi ⁿ (t) = fi ^ref (t) * {SOC ⁿ / SOC ^ref }
* {SONi ⁿ / SOHi ^ref } * g (T) (1)
(Wherein, Sohi ⁿ is for each of the reaction rate SOH)
It is characterized by being expressed.

  In another aspect of the state detection method of the power storage device of the present invention, the voltage and current of the power storage device are measured, and it is determined that the power storage device has stopped charging / discharging from the current or a predetermined charge / discharge stop signal. Then, the voltage change amount at the time of stop corresponding to the elapsed time from the charge / discharge stop is calculated from the voltage measurement value, and the relaxation rate fi for each reaction rate corresponding to the reaction rate having a time constant shorter than the elapsed time. (T) is optimized using the amount of change in voltage at the time of stop, and the immediately preceding one is used for the relaxation rate fi (t) for each reaction rate corresponding to the reaction rate longer than the time constant. The state quantity is estimated from the optimized relaxation function fi (t) for each reaction rate, the discharge end voltage, and the charge end voltage.

  In another aspect of the method for detecting a state of an electricity storage device of the present invention, the stable voltage at the time of stop is the voltage when the voltage after the charge / discharge stop of the electricity storage device becomes a fluctuation amount of 5 mV or less per hour. It is characterized by that.

  Advantageous Effects of Invention According to the present invention, it is possible to provide a state detection method for an electricity storage device for accurately evaluating the discharge ability of an electricity storage device with reaction processes having different speeds, and whether or not the discharge ability of the electricity storage device is ensured. Can be accurately determined.

It is a flowchart explaining the state detection method of the 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the state detection system using the state detection method of 1st Embodiment. It is a flowchart which determines the timing which performs the data measurement required for a state detection. It is a flowchart explaining the method to determine charging / discharging stop. It is a flowchart explaining the selection method of OCV _20hr . It is a flowchart explaining the method of optimizing F (t). It is a flowchart explaining the method of optimizing F (t). It is a flowchart explaining the method of calculating state quantity SOH and SOC. It is a graph which shows an example of a relaxation function and a relaxation function for every reaction rate. It is a graph which shows an example of the relaxation function for every reaction rate, and its ratio. It is a graph which shows an example of a stable OCV estimation formula. It is a graph which shows the relationship between a stable open end voltage and SOC. It is a graph which shows the change of OCV when SOC is constant. It is a graph which shows the change of OCV when SOH differs. It is a flowchart explaining the state detection method of the 2nd Embodiment of this invention. It is a graph which shows an example of charging efficiency (eta) 1 and (eta) 2. It is a flowchart explaining the state detection method of the 3rd Embodiment of this invention. It is a graph which shows an example of the change of the relaxation function for every reaction rate. It is a graph which shows an example of the change of SOH with respect to a quick reaction rate. It is a graph which shows an example of the correction coefficient with respect to SOH. It is a flowchart explaining the determination method of the state quantity in 3rd Embodiment. It is a schematic diagram for stratification of an electrical storage device.

  A power storage device state detection method according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

  In the state detection method for an electricity storage device according to the present invention, a transient change of the electricity storage device after stopping charging / discharging is viewed as a change in voltage measurable from the electricity storage device. In other words, the voltage when the storage device stops charging / discharging and reaches a state where the predetermined stability condition is satisfied is defined as the stable voltage at stop, and the amount of change from the stable voltage at stop after the charge / discharge stop is used. To detect the state of the electricity storage device in a transient state. Hereinafter, the amount of change from the stable voltage at the stop of the voltage measurement value when the time t has elapsed since the storage device has stopped charging / discharging is referred to as the stop voltage change.

  In the state detection method for an electricity storage device of the present invention, a relaxation function F (t) that depends on a predetermined state amount of the electricity storage device is created and used in advance as a function for calculating the amount of voltage change at the time of stop. Then, the relaxation function F (t) is optimized using the amount of change in the stop voltage obtained from the voltage measurement value, and the state is detected by estimating a predetermined state quantity from the optimized relaxation function F (t). Yes. In the state detection method of the present invention, a voltage state immediately before stopping charging / discharging is detected, a predetermined state quantity is estimated using the above relaxation function F (t), and the estimated state quantity is set in advance. It is determined whether the discharge capability (COD) of the electricity storage device is properly maintained by comparing with the determination criteria. As the predetermined state quantity, for example, SOH (State of health) which is an indicator of the degree of deterioration of the power storage device, SOC indicating the remaining capacity, or the like can be used.

  There are transient changes in electricity storage devices after charge / discharge stoppages, from those with fast reaction speeds, such as ion generation / annihilation reactions, to those with slow reaction speeds, such as electrolyte migration. It affects the change in the state quantity. Therefore, in the state detection method for an electricity storage device of the present invention, a change in state quantity for each reaction rate is estimated using a relaxation function F (t), and these are integrated to determine the state quantity. For example, the state quantity at the time when the elapsed time after the end of charge / discharge is short is determined in consideration of the influence of the slow reaction rate.

  As the stable voltage at the time of stop, an open-circuit voltage OCV (hereinafter referred to as a stable time OCV) of the electricity storage device when a sufficient time has elapsed since charging / discharging is stopped is known. OCV is a voltage between terminals when the terminal of the electricity storage device is opened and discharge is stopped. The stable voltage at the time of stop used in the method for detecting the state of the electricity storage device of the present invention is not limited to OCV, and when the transient influence on the electricity storage device is limited, the stable voltage at that time can be used. As an example, a minute current (dark current) may be supplied to the load control device while the power supply from the power storage device to the load is stopped. Even when the load is stopped, the voltage when a sufficient time elapses after the load is stopped can be set as the stable voltage at the time of stop.

  In addition, even when the charge / discharge amount from the electricity storage device is always a constant value, the transient effect on the electricity storage device is considered to be sufficiently small, so when sufficient time has passed since the load was stopped. The voltage can be a stable voltage when stopped. In this way, when the current due to charging / discharging is small or constant and the influence on the transient change inside the electricity storage device is limited within a predetermined range, when the power supply to the load is stopped, In addition to determining that the discharge has stopped, the voltage when a long time has elapsed after stopping the charge / discharge in a state where a minute current or a constant current is continued can be set as a stable voltage at the time of stop. In this case, it is preferable that a voltage correction amount for correcting a voltage change due to a minute current or a constant current is determined in advance, and the voltage measurement value is corrected using this.

The following description will be made using a stable OCV as an example of a stable voltage at a stop. When the OCV at the time of stability is used, the state quantity SOC can be expressed by the following equation using the relationship shown in FIG.
SOC = FS (OCVs (SOC, SOH, T)) (2)
OCV _s (SOC, SOH, T) = lim (V _mes (t)) (3)
Here, OCV _s represents the stable OCV, and T represents the temperature of the electricity storage device. In addition, lim in the above expression indicates that the elapsed time t from the charge / discharge stop is infinite, and the right side of the expression (3) indicates the power storage device when the elapsed time after the charge / discharge stop is infinite. The voltage measurement value V _mes (t) is shown. Similarly, when using a stable voltage at the time of stop other than the stable OCV, a relational expression similar to the above can be created in advance with the SOC.

  The above equation shows that the SOC is determined depending on the OCVs, and at the same time, the OCVs is also dependent on the SOC, and further changes depending on the state quantity SOH and the temperature T of the power storage device. ing. Moreover, since OCVs depends on another state quantity SOH, the state quantity SOC also depends on SOH, and it is necessary to perform each update at an appropriate timing.

OCV _s is V _mes (t) when the elapsed time t from charge / discharge stop is infinite as shown in the equation (3), but in practice, when the change of V _mes (t) is sufficiently small. V _mes (t) at the time of a possible elapsed time t can be used. In addition, when the electricity storage device is a liquid lead acid battery, OCV _s is V _mes (t) when the amount of change in OCV per hour is 5 mV or less, or when 20 hours have elapsed from the stop of charge / discharge. It can be. Below, the storage device state detection method of the present invention will be described by taking as an example the case where the storage device is a storage battery such as a liquid lead storage battery.

Below, _Vmes (t) when 20 hours have passed since the charge / discharge stop of the storage battery is assumed to be OCV _20hr of the following equation, and this is used for OCV _s .
OCV _20hr = _Vmes (t = 20hr)
OCV _s (SOC, SOH, T) ≈OCV _{20 hr} (4)

When the amount of change from the stable OCV of the voltage measurement value V _mes (t) after charge / discharge stop, that is, the OCV change amount (voltage change amount at stop) is ΔV (t),
ΔV (t) = V _mes (t) −OCV _{20 hr} (5)
It can be expressed as. This voltage change amount ΔV (t) has been handled including all transient changes using the term “polarization” in the conventional definition of electrochemistry. However, ΔV (t) is a voltage change caused by the relaxation process until it approaches the stable OCV, and is therefore affected by the following voltage change factors. Factors of voltage change include the electrode plate state, the ion concentration in the vicinity of the electrode plate, their solid-phase reaction, solid-liquid reaction, and precipitation and convection of the electrolyte solution, and ion movement accompanying diffusion. ΔV (t) is considered to be caused by a combination of relaxation processes having different reaction rates.

ΔV (t) is expressed as follows using a function F (t) made up of m polynomials according to the difference in reaction rate.
ΔV (t) = F (t)
= F ₁ (t) + f ₂ (t) +... F _m (t) = Σf _i (t) (6)
In the above relaxation function F (t), each term f _i (t) indicates the contribution to the voltage change of the relaxation process with different reaction speeds of the storage battery. Hereinafter, the relaxation function for each reaction speed f _i (t) And Each f _i (t) is a function that depends on the deterioration degree SOH, which is the state quantity of the storage battery, the remaining capacity SOC (ion concentration), and the temperature T. The relaxation function f _i (t) for each reaction rate in the equation (6) is optimized using ΔV (t) calculated from the voltage measurement value V _mes (t) after stopping charging and discharging. Can be determined.

In the state detection system using the state detection method of the present invention, the initial values SOC ⁰ , SOH _i ⁰ , and OCV _{20 hr} ⁰ of SOC, SOH, and OCV _{20 hr} before the state detection is started are _stored in the state detection system. The respective reference values SOC ^{ref (0)} , SOH _i ^{ref (0)} , and OCV _20hr ^{ref (0)} stored in advance can be set as follows.
SOC ⁰ = SOC ^{ref (0)}
SOH _i ⁰ = SOH _i ^{ref (0)}
OCV _{20 hr} ⁰ = OCV _{20 hr} ^{ref (0)}
Here, the reference values SOC ^{ref (0)} , SOH _i ^{ref (0)} , and OCV _{20 hr} ^{ref (0)} are values acquired in advance by different batteries.

The relaxation function F (t) of the equation (6) representing the OCV variation ΔV (t) after the nth (n is an integer of 1 or more) charge / discharge stop after the state detection is started by the state detection system. and the reaction rate for each relaxation function _f i a (t), respectively ^F n _(t), when the ^{f i} n (t), SOC corresponding to the i-th reaction rate and SOH (respectively ^SOC n, and _SOH ^{i n} Therefore, it is assumed that the relaxation function fi _n (t) for each reaction rate is expressed by the following equation.
^{_{f in (t) = f i}} ref (t) * {SOC n / SOC ref}
* {SOH _i ⁿ / SOH _i ^ref } * g (T) (7)
^{_{Here, f i ref (t),}} SOC ref, SOH i ref is, _f i (t) in the predetermined initial state (e.g. unused state), SOC, a SOH _i, g (T) is It is a function representing temperature dependence.

If the temperature T and the SOC is constant regardless of the time in equation (7) is, _SOH ^{i n} the ^{_{SOH i n = {f i n}} (t) / f i ref (t)} * SOH i ref (8 )
It can be calculated from Therefore, it optimizes the _f ⁱ n (t) of formula (6) [Delta] V (t) that is calculated from the voltage measured value _{V mes} (t), calculates the _SOH ^{i n} from equation (8) using the same Can do.

After calculating the SOH _i ⁿ different reaction rate transients per the equation (8), the SOH ⁿ of the total, which is calculated by integrating these,
SOH ⁿ = (SOH ₁ ⁿ , SOH ₂ ⁿ ,..., SOH _m ⁿ ) (9)
It can be expressed as For example, if m coefficients are A to M for m SOH _i ,
SOH ⁿ = A * SOH ₁ ⁿ + B * SOH ₂ ⁿ + ... + M * SOH _m ⁿ
= A * {f ₁ ⁿ (t) / f ₁ ^ref (t)} SOH ₁ ^ref +
B * {f ₂ ⁿ (t) / f ₂ ^ref (t)} SOH ₂ ^ref +... +
M * {f _m ⁿ (t) / f _m ^ref (t)} SOH _m ^ref (9-1)
It can be expressed as. However, Formula (9-1) is an example representing the relational expression of Formula (9), and is not limited to this. Using the SOH ⁿ calculated as described above, the deterioration state of the storage battery can be detected. Similarly, SOC ⁿ which is another state quantity can be calculated using the optimized relaxation function F (t).

Since the relaxation function F (t) shown in Equation (6) has a relaxation function f _i (t) for each reaction rate with different reaction rates, the elapsed time is short after the nth charge / discharge stop. In some cases, f _i ⁿ (t) corresponding to a slow reaction rate cannot be optimized. As a result, ^SOC n by using the relaxation function F (t), it is not possible to update the _SOH ^{i n.} Therefore, slow corresponds to the reaction rate _f ⁱ n Optimization (t) until a ^possible, SOC n, the value ^SOC n-1 at the previous charge and discharge stop instead of the _SOH ^{i n,} _SOH ^{i n- 1} is used, and the expression (7) is approximately expressed as the following expression.
f _i ⁿ (t) = f _i ^ref (t) * {SOC ⁿ⁻¹ / SOC _i ^ref }
* {SOH _i ^n-1 / SOH _i ^ref } * g (T) (7-1)

When (7-1) can be used for f _i ⁿ (t) corresponding to a slow reaction rate, it becomes possible to detect the state from a point in time after a short time has elapsed after stopping charging and discharging. In particular, when charging / discharging is performed only below a predetermined threshold, the relaxation function F ⁿ (t) using SOC ⁿ⁻¹ and SOH _i ⁿ⁻¹ after the end of the previous charging / discharging is used for state detection. It becomes possible.

On the other hand, for the remaining capacity SOC of the storage battery, the charge / discharge current during the period from the end of the previous (n-1) charge / discharge stop until the current (nth) charge / discharge stop It is possible to calculate the remaining capacity change ΔSOC by integrating, and using this, SOC ⁿ can be calculated by correcting the previous remaining capacity SOC ⁿ⁻¹ . That is,
SOC ^n-1 '= SOC ^n-1 + ΔSOC
And using this instead of SOC ⁿ , equation (7) can be approximated as:
f _i ⁿ (t) = f _i ^ref (t) * {SOC ⁿ⁻¹ ′ / SOC ^ref }
* {SOH _i ^n-1 / SOH _i ^ref } * g (T) (7-2)

Using the SOH _i ⁿ calculated by the equation (8), f _i ⁿ (t) is updated by the following equation, and this is used to calculate the SOC _i ⁿ .
f _i ⁿ (t) = f _i ^ref (t) * {SOC _i ⁿ⁻¹ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref } * g (T) (7-3)

From Expression (5) and Expression (7-3), OCV _20hr can be calculated by the following expression.
_{OCV 20hr = V mes (t)} -Σ [f i ref (t) * {SOC n-1 / SOC ref} * {SOH i n / SOH i ref}] * g (T) ( Equation 10)
By substituting this OCV _{20 hr} into (Equation 2), SOC ⁿ can be calculated and used for SOC state detection.

As described above, m reference values f _i ^ref (t) (i = 1 to m) corresponding to m kinds of reaction rates, and m deterioration degree reference values SOH _i ^ref (i = 1 to m). Based on the reference value SOC ^ref of one remaining capacity, m relaxation functions f _i ⁿ (t) (i = ^{1 to} m) after the nth charge / discharge stop are calculated. Can do. As a result, it is possible to detect OCV, SOC, and SOH reflecting the degree of deterioration corresponding to different reaction rates and to perform highly accurate state detection.

  A method for detecting the state of an electricity storage device according to the first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a flowchart showing a process flow according to the state detection method of the present embodiment. FIG. 2 is a block diagram showing a schematic configuration of a state detection system using the state detection method of the present embodiment. The state detection system 10 shown in FIG. 2 is configured to detect the state of the storage battery 1 mounted on the vehicle as an example. Charging means 2 and a load 3 are connected to the storage battery 1 and charging by the charging means 2 and discharging to the load 3 are possible. Further, the storage battery 1 is provided with a temperature measuring means 1a, a voltage measuring means 1b, and a current measuring means 1c, and each measured value can be input to the state detection system 10 via the input means 4. Yes. Furthermore, the control apparatus 5 which controls charging / discharging of the storage battery 1 is provided. It is also possible to input control information from the control device 5 via the input means 4 to the state detection system 10.

  The state detection system 10 includes an arithmetic unit 11, a fixed storage unit (ROM) 12, a temporary storage unit (RAM) 13, a timer 14, and a state output unit 15. The arithmetic device 11 inputs the temperature measurement value, the voltage measurement value, and the current measurement value of the storage battery 1 using the input unit 4 and stores them in the temporary storage unit 13. Further, the fixed storage means 12 stores a reaction rate relaxation function fi (t), initial values and reference values of various state quantities. The arithmetic unit 11 uses the initial value and the reference value stored in the fixed storage unit 12, the voltage measurement value stored in the temporary storage unit 13, and the like, at a predetermined time period counted by the timer 14. It is configured to detect the state and output the result to the state output means 15. The output information of the state output means 15 can also supply control parameter information for use by the control device 5.

The state detection method of the present embodiment will be described below using the flowchart shown in FIG. First, in step S <b> 1, the voltage measurement value and the current measurement value of the storage battery are input using the input unit 4. In the next step S2, it is determined from the input current measurement value whether charging / discharging has been stopped. If it is determined that the charge and discharge stop has been initiated, and stores a voltage measurement value of the immediately preceding step S3 in the temporary storage 13 as the discharge end voltage V _DE or charging end voltage V _CE. The next step in the case in step S4, compared to ^{V ref} of the reference values stored discharge end voltage _{V DE} or charging end voltage _{V CE} in the fixed storage unit 12, higher than the reference value ^{V ref} Proceed to S5. On the other hand, when the discharge end voltage V _DE or the charge end voltage V _CE is lower than the reference value V ^ref , it is determined that the discharge capacity COD is insufficient, and the process proceeds to step S13 to indicate the COD shortage as the state output means 15 To output.
Here, V ^ref is a value (for example, 12.8 V) measured in advance with another battery.

If it is determined in step S4 that the discharge end voltage _VDE or the charge end voltage _VCE is equal to or higher than ^Vref, it is determined in step S5 whether charging / discharging is stopped or charging / discharging is resumed. If it is determined that charging / discharging has been resumed, the state detection is terminated. On the other hand, when the charge / discharge stop is continued, the voltage measurement value is set to V _mes and stored in the temporary storage means 13 in step S6. In the next step S7, OCV _20hr which is a stable voltage at the time of stop is selected, and ΔV (t) is calculated in step S8 using this and the voltage measurement value _Vmes .

  In step S9, the relaxation function F (t) is optimized using ΔV (t) calculated in step S8. Regarding the fitting method, there are various methods of calculation using regression calculation such as the least square method. However, in this fitting, ΔV (20 hr) = 0, so that the regression is simply performed using the sum of exponential functions. If the calculation is performed, the error becomes large. Therefore, by subtracting the slope of the tangent line near ΔV (20 hr) = 0, a function that always satisfies ΔV (20 hr)> 0 (for example, Expression (11-4) described later) is introduced, and the difference is calculated. It is desirable to perform fitting by the sum of exponential functions.

In step S10, a predetermined state quantity (hereinafter referred to as S) is estimated using the optimized relaxation function F (t). In step S11, the estimated state quantity S is compared with the reference value S ^ref stored in the fixed storage means 12, and when it is determined that the state quantity S satisfies a predetermined condition, the process proceeds to step S12 and COD is determined. The fact that it is secured is output to the status output means 15. On the other hand, if it is determined in step S11 that the state quantity S does not satisfy the predetermined condition, the process proceeds to step S13 to output to the state output means 15 that the COD is insufficient.

In the storage battery state detection method of the present embodiment, the SOC calculation formula (2) and the reference values SOC ^{ref (0)} , SOH ^{ref (0)} , OCV _20hr ^{ref (} SOC, SOH, OCV _20hr corresponding to initial values ^{) 0)} is stored in advance in the fixed storage means 12, and the initial values thereof are used as SOC ⁰ = SOC ^{ref (0)} , SOH _i ⁰ = SOH _i ^{ref (0)} , OCV _20hr ⁰ = OCV _20hr ^ref. Set to ⁽⁰⁾ .

  Details of the processing in step S1 are shown in FIG. In FIG. 3, the timer count value is confirmed at a predetermined confirmation timing, and when the timer count (t_count) exceeds the measurement timing value for the predetermined measurement timing (step S1-2). The voltage and current of the storage battery 1 are input from the input means 14 (step S1-4).

  FIG. 4 shows an example of a method for determining whether to stop charging / discharging the storage battery 1 in step S2. The charge / discharge stop is determined when the measured current value measured in step S2-2 is equal to or less than a predetermined threshold stored in the fixed storage unit 12 (step S2-4). Is determined to be parked or stopped, or information indicating that the state detection device 10 is connected to the storage battery 1 is input to the computing device 11 (step S2-1), using these pieces of information. Charge / discharge stop can also be determined (step S2-3).

The OCV _20hr selection method in step S7 is shown in the flowchart of FIG. n th _{OCV 20 hr} calculated at the start of the ^SOC n, the SOH ^n, using a previous calculation value ^{SOC n-1, SOH n-} 1 ( step S7-1). The current temperature T of the storage battery 1 uses the measured value input from the input means 4 (step S7-2). _Assuming that the OCV _20hr selected by this is OCV _20hr ^temp , a relational expression created in advance under h types of conditions combining a plurality of SOC and SOH values and temperatures.
H (SOC_j, SOH_k, T_l) = OCV _{20 hr} ^{ref (h)} (h, j, k, l are natural numbers)
Using (step _S7-4), the _OCV ^{20 hr temp} set by the following equation (step S7-5).
OCV _{20 hr} ^temp = OCV _{20 hr} ^{ref (h)}

In the following, for the sake of simplicity, Equation (6) shall be composed of the following four terms.
F (t) = f _fast (t) + f _slow (t)
= {F _fast1 (t) + f _fast2 (t)} +
{F _slow1 (t) + f _slow2 (t)} (11)

As one embodiment, for example, (Equation 11) is a function of fast relaxation rate 1: f _fast1 (t) = A * exp (−B * t ^ C) (11-1)
Fast relaxation rate function 2: f _fast2 (t) = D * exp (-E * t ^ F) (11-2)
Slow relaxation rate function 1: f _slow1 (t) = G * exp (-H * t ^ I) (11-3)
Slow relaxation rate function 2: f _slow2 (t) = − a / 72000 * t + b (11-4)
This makes it easy to create a function that optimizes ΔV (t). However, a complicated or simplified version of this function is used depending on the calculation speed of the calculation device 11, the memory capacity of the fixed storage means 12, the temporary storage means 13, and the accuracy conditions required for the measurement sensor. May be.

A method for obtaining F ⁿ (t) from ΔV (t) according to the elapsed time of the timer count (step S9) will be described with reference to FIGS. The functions shown in the equations (11-1) to (11-4) are fitted so that each of them is dominant in the section divided by four reference times (10 seconds, 1000 seconds, 36000 seconds, 72000 seconds). Thus, each coefficient is determined. Here, the reference time (10 seconds, 1000 seconds, 36000 seconds, 72000 seconds) is an example, and can be set according to the relaxation characteristics of the reaction rate of the storage battery. In addition, the reference time can be changed not only by the reaction speed inside the storage battery but also by the running condition and rest condition in the actual vehicle, the required accuracy of the sensor, and the like.

A method for obtaining F ⁿ (t) from ΔV (t) when the elapsed time after charging and discharging is stopped is shorter than 20 hours will be described with reference to FIG. The original a (step S9-1), the calculated value ^{F n-1} after the previous charge-discharge stop (t) when the time t is determined to less than the first reference time (10 seconds), ^{F n} (T) is calculated by the following equation (step S9-2).
F ⁿ (t) = f _fast1 ⁿ⁻¹ (t) + f _fast2 ⁿ⁻¹ (t) +
_fslow1n ^-1 (t) + _fslow2n ^-1 (t)} (12)

Similarly, when it is determined that the time t is equal to or longer than the first reference time and shorter than the second reference time (1000 seconds) (step S9-3), F ⁿ⁻¹ ( Based on t) and the latest data, F ⁿ (t) is calculated by the following equation (step S9-4).
F ⁿ (t) = f _fast1 ⁿ (t) + f _fast2 ⁿ⁻¹ (t) +
_fslow1 ^n-1 (t) + _fslow2 ^n-1 (t)} (13)

When it is determined that the time t is equal to or longer than the second reference time and shorter than the third reference time (36000 seconds) (step S9-5), F ^n-1 (t) after the end of the previous charge / discharge. Based on the latest data, F ⁿ (t) is calculated by the following equation (step S9-6).
F ⁿ (t) = f _fast1 ⁿ (t) + f _fast2 ⁿ (t) +
_fslow1n ^-1 (t) + _fslow2n ^-1 (t)} (14)

When it is determined that the time t is equal to or longer than the third reference time and shorter than the fourth reference time (72000 seconds) (step S9-7), F ^n-1 (t) after the end of the previous charge / discharge. Based on the latest data, F ⁿ (t) is calculated by the following equation (step S9-8).
F ⁿ (t) = f _fast1 ⁿ (t) + f _fast2 ⁿ (t) +
_{^{f slow1 n (t) + f}} slow2 n-1 (t)} (15)
OCV _{20 hr} ⁿ = F ⁿ (20 hr) by substituting t = 20 hours for F ⁿ (t) obtained from the above equations (12) to (15).
Is obtained (step S9-11).

When it is determined that the time t is equal to or greater than the fourth reference time (for example, 20 hours) (step S9-7), as shown in FIG. 7, the OCV _20hr ^temp obtained from the latest V _mes (20hr), ΔV ⁿ (t) = ΔV (t) ^temp + OCV _{20 hr} ^temp −OCV _{20 hr} ⁿ (16) based on ΔV (t) recorded so far (ΔV (t) ^temp )
ΔV ⁿ (t) is calculated (step S9-13), and F ⁿ (t) is calculated by the following equation (step S9-15).
F ⁿ (t) = f _fast1 ⁿ (t) + f _fast2 ⁿ (t) +
^{_{f slow1 n (t) + f}} slow2 n (t)} (17)

FIG. 8 shows f _i (t) calculated in the processing of FIGS. 6 and 7 and stored in the temporary storage unit 13, the reference value f _i ^ref (t) previously stored in the fixed storage unit 12, and SOH _i. with _^ref, it shows a flow of processing in step S10 of calculating ^SOH i n, the SOC. The OCV _{20 hr} ⁿ , the reference value f _i ^ref (t), the SOH _i ^ref and the temperature T ⁿ obtained above are read from the storage means 12 and 13 (steps S10-1 and 2) and stored in the fixed storage means 12. and the function being ^{_{I (OCV 20hr_ n, SOH i}} n, T n) = calculates the ^{SOC REF_N} by substituting the respective values into the relational expression of the ^{SOC REF_N} (step S10-6), now ^SOC n ^{= SOC ref_n} Is calculated (step S10-7).

As an example of optimization of the relaxation function F (t) in the storage battery state detection method of the present embodiment, an example of changes in each term when the relaxation function F (t) is expressed as in Expression (11) As shown in FIG. FIG. 9 is a graph showing changes in ΔV (t) (= F (t)) when the horizontal axis is the elapsed time from the end of charge / discharge, and reference numerals 51 to 54 denote the respective terms of the equation (11). _{Changes in} (f _fast1 (t), f _fast2 (t), f _slow1 (t), and f _slow2 (t)) are shown. Reference numeral 50 indicates a true value, and reference numeral 55 indicates a value of F (t) calculated from (Equation 11). It is shown that ΔV (t) can be predicted with high accuracy by using F (t) of the present embodiment.

In the following, the degree of stratification of the slow reaction rate (diffusion of electrolyte, etc.) is SOH ₁ (i = 1) in formula (8), and SOH ₁ ⁿ after the ^nth charge / discharge is
SOH ₁ ⁿ = f _slow ⁿ (t) / f _slow ^ref * SOH ₁ ^{ref
_{= {F slow1 n (t)}} + f slow2 n (t)} /
{F _slow1 ^ref (t) + f _slow2 ^ref (t)} * SOH ₁ ^ref
(Formula 18)
It shall be calculated by In the above, f _i ⁿ (t) and f _i ^ref (t) in equation (8) are further added to the sum of two terms {f _slow1 ⁿ (t) + f _slow2 ⁿ (t)}, {f _slow1 ^ref (t) It is assumed that it is calculated from + f _slow2 ^ref (t)}.

As an example, using a liquid lead acid battery of size model number 55D23 manufactured by Furukawa Battery, under the conditions of an environmental temperature of 25 ° C. and a DOD (Depth of discharge) of 10%, 20 charge / discharge cycles from an unused state are performed 50 times. And 100 runs. Based on the measurement data after 20 cycles of charge / discharge, 50 cycles of charge / discharge, and 100 cycles of charge / discharge, 5 hours elapsed (t = 5 hours) from the end of charge / discharge. SOH ₁ ⁿ is calculated from the OCV change amount f _i ⁿ (5 hr) at the time as shown in the following equation.
^{_{SOH 1 50 = {f slow1 50}} (5hr) + f slow2 50 (5hr)} /
{F _slow1 ²⁰ (5 hr) + f _slow2 ²⁰ (5 hr)} * SOH ₁ ²⁰ (formula 19)
SOH ₁ ¹⁰⁰ = {f _slow ^{1 100} (5 hr) + f _{slow 2} ¹⁰⁰ (5 hr)} /
{F _slow1 ²⁰ (5 hr) + f _slow2 ²⁰ (5 hr)} * SOH ₁ ²⁰ (formula 20)

FIG. 10 shows f _slow ⁿ (t) / f _slow ²⁰ (t) calculated from the measurement data. Reference numerals 61, 62, and 63 denote f _slow ²⁰ (t), f _slow ⁵⁰ (t), and f _slow ¹⁰⁰ (t), respectively, and reference numerals 64 and 65 denote f _slow ⁵⁰ (t) / f _slow ²⁰ ( t), f _slow ¹⁰⁰ (t) / f _slow ²⁰ (t). From the figure, for example, at the time of t = 18000 seconds, {f _slow1 ⁵⁰ (5 hr) + f _slow2 ⁵⁰ (5 hr)} /
{F _slow1 ²⁰ (5 hr) + f _slow2 ²⁰ (5 hr)}
= F _slow ⁵⁰ (5 hr) / F _slow ²⁰ (5 hr)
= 1.52

Similarly,
f _slow ¹⁰⁰ (5 hr) / f _slow ²⁰ (5 hr)
= 1.63
Is obtained. Thus, it becomes possible to grasp the change in the battery state according to the number of charge / discharge cycles from the change amount F (t) of the OCV.

Further, OCV when the elapsed charge and discharge after the end of 20 hours as an example, with respect to the charge-discharge cycle number ^{_{20,50,100 OCV 20hr 20 = 12.896 [V}} ]
OCV _{20 hr} ⁵⁰ = 13.032 [V]
OCV _{20 hr} ¹⁰⁰ = 13.036 [V]
FIG. 11 shows the relationship between the above f _slow ⁿ (t) / f _slow ²⁰ (t) and the OCV _{20 hr} ²⁰ . The result shown in FIG. 11 can be used for the stable OCV estimation formula for estimating the OCV _{20 hr of the} same type of storage battery.

  As described above, according to the present invention, it is possible to provide a state detection method for a storage battery that performs state detection by evaluating deterioration due to reaction processes having different speeds. By detecting the deterioration degree SOH of the battery, it is possible to accurately detect the remaining capacity SOC.

The state detection method of the electrical storage device which concerns on the 2nd Embodiment of this invention is demonstrated below using FIG. FIG. 15 is a flowchart showing a process flow according to the state detection method of the present embodiment. In the present embodiment, after determining the COD based on the discharge end voltage _{V DE} or charging end voltage _{V CE} in step S4 of the first embodiment, the remaining capacity _{SOC stop} ⁿ during charging and discharging is stopped in step S21 Is used to determine the COD. That is, in step 21, the remaining capacity SOC _stop ⁿ is compared with the reference value SOC _stop ^ref stored in the fixed storage means 12, and if the remaining capacity SOC _stop ⁿ is greater than or ^equal to the reference value SOC _stop ^ref , the next step Proceeding to and after S5, if smaller than the reference value SOC _stop ^ref, it is determined that the COD is insufficient, and the process proceeds to step S13. Thereby, the discharge capability of the storage battery 1 can be determined with higher accuracy.

A method of calculating the remaining capacity SOC _stop ⁿ when charging / discharging is stopped will be described with reference to FIG. With respect to the SOC _stop ⁿ⁻¹ calculated at the time of stopping the charging / discharging, the SOC increased / decreased after the charging / discharging is restarted until the current charging / discharging stop (this is set as the remaining capacity increase / decrease amount ΔSOC) is corrected. By doing so, the remaining capacity SOC _stop ⁿ at the current charge / discharge stop can be calculated. The remaining capacity increase / decrease amount ΔSOC can be calculated by integrating the charge / discharge current of the storage battery 1 from the previous charge / discharge restart to the current charge / discharge stop.

In the present embodiment, the ΔSOC calculated as described above is further subjected to a predetermined correction so that the remaining capacity increase / decrease amount can be calculated with higher accuracy. In the state detection method of the present embodiment, the remaining capacity SOC _stop ⁿ when charging / discharging is stopped is calculated by the following equation.
SOC _stop ⁿ = SOC _stop ⁿ⁻¹ + ΔSOC * η ₁ ⁿ⁻¹ * η ₂ ⁿ⁻¹ (21)
Here, η ₁ ⁿ⁻¹ is a function of slow relaxation rate f _slow (10 hr) (f _{slow1 in} equation (11-3) or f _{slow2 in} equation (11-4)) as shown in _FIG . Η ₂ ⁿ⁻¹ is a correction coefficient determined depending on the charging end voltage V _CE ⁿ as shown in FIG. 16B. These correction coefficients correct the charging efficiency of the storage battery 1.

The state detection method of the electrical storage device which concerns on the 3rd Embodiment of this invention is demonstrated below using FIG. FIG. 17 is a flowchart showing a process flow according to the state detection method of the present embodiment. In the present embodiment, the processing method of steps S10 and S11 is changed to step S30 in the processing of the second embodiment shown in FIG. In steps S10 and S11 of the second embodiment (the same applies to the first embodiment), a predetermined state quantity S is calculated and compared with the reference value S ^ref stored in the fixed storage unit 12 to obtain the state. It was determined whether or not the amount S satisfies the condition indicating that the discharge capacity is maintained. On the other hand, in step S30 of the present embodiment, the state quantity S is evaluated for each reaction rate, and it is determined whether the condition for maintaining the discharge capacity is satisfied for each reaction rate. Also, the determination based on the ratio between the slow reaction rate and the fast reaction rate is performed.

Taking the deterioration degree SOH as an example of the state quantity S, the determination method for each reaction rate and the determination method based on the ratio between the slow reaction rate and the fast reaction rate will be described below. The degree of deterioration SOH _fast ⁿ and SOH _slow ^{n for} each reaction rate can be calculated as follows using equation (8).
SOH _fast ⁿ ′ = {f _fast ⁿ (t) / f _fast ^ref_n (t)} * SOH _fast ^ref (22)
SOH _slow ⁿ = {f _slow ⁿ (t) / f _slow ^ref_n (t)} * SOH _slow ^ref (23)
Furthermore, the total SOH ⁿ obtained by integrating the degradation degrees SOH _fast ⁿ and SOH _slow ⁿ for each reaction rate is expressed as in Expression (9), and can be calculated from Expression (9-1), for example.

The degree of deterioration SOH _{fast / slow} calculated based on the ratio between the slow reaction rate and the fast reaction rate can also be calculated by the following equation in the same manner as described above.
SOH _{fast / slow} ⁿ = {f _{fast / slow} ⁿ (t) / f _{fast / slow} ^ref_n (t)} * SOH _{fast /} ^slow_ref (24)
The degradation degree SOH _{fast / slow} ⁿ calculated based on the ratio of the slow reaction speed and the fast reaction speed is obtained by using the ratio of the slow reaction speed and the fast reaction speed as shown in FIG. It becomes possible to evaluate a change in the degree of deterioration based on a large change event, either a speed transient event or a slow reaction rate transient event.

For SOH _fast ⁿ ′ calculated by the above equation (22), in order to correct the influence of the remaining capacity SOC _stop ⁿ which is the state quantity at the time of stopping charging and discharging and the voltage V _CE ⁿ at the time of charging end, The degree of degradation SOH _fast ⁿ is calculated by the following equation. This correction corrects the fact that SOH _fast ⁿ changes as shown in FIG. 19 with respect to a high reaction rate.
SOH _fast ⁿ = SOH _fast ⁿ ′ * α ₁ ⁿ * α ₂ ⁿ (25)
The correction parameters α ₁ ⁿ and α ₂ ⁿ show changes as shown in FIGS. 20A and 20B, for example, with respect to the remaining capacity SOC _stop ⁿ and the charging end voltage V _CE ⁿ . Accordingly, the change shown in FIGS. 20A and 20B is expressed by a predetermined function (high-speed transient change correction amount calculation formula), so that the correction parameter α ₁ is calculated from the remaining capacity SOC _stop ⁿ and the charging end voltage V _CE ^{n. n} and α ₂ ⁿ can be calculated.

In the above description, correction of SOH _fast ⁿ has been described. For SOH _slow ⁿ , for example, formulas for calculating correction parameters β ₁ ⁿ and β ₂ ⁿ are created in advance, and the correction is similarly performed using this formula. It is possible.

The SOD _fast ⁿ , SOH _slow ⁿ , and SOH _{fast / slow} ⁿ calculated as described above are used, and compared with the respective reference values as shown in FIG. 21, the COD of the storage battery 1 can be determined. . In FIG. 21, the state quantity is represented by S _fast or the like, but when SOH is evaluated, it is replaced with SOH _fast ⁿ or the like. In step S31, SOH _slow ⁿ is calculated using equation (23), and in step S32, it is compared with a reference value SOH _slow ^ref_n . As a result, when the SOH _slow ⁿ is less than the SOH _slow ^ref_n , it is determined that the COD is insufficient, and the process proceeds to step S13. Otherwise, the process proceeds to the next step S33.

Similarly, SOH _fast ⁿ is determined in steps S33 and S34, and SOH _{fast / slow} ⁿ is determined in steps S35 and S36. If any of the predetermined conditions is satisfied, the process proceeds to step S12 and it is determined that the COD is maintained. In the present embodiment, it is possible to detect the state of the storage battery 1 with high accuracy by performing the processing as shown in FIGS.

  In the above, the embodiment has been described in which SOC and SOH are calculated as the state quantities of the power storage device, and the state detection is performed using them. The state detection method of the electricity storage device of the present invention is not limited to this, and other state quantities relating to the discharge capability of the electricity storage device can be used. In addition to the SOC and SOH, as a state quantity that can be used for determining the discharge capability of the electricity storage device, there is a concentration change amount of the electrolytic solution in the electricity storage device. The density | concentration of electrolyte solution is changing with charging / discharging, and it takes time until it stabilizes even after charging / discharging stops.

Therefore, in order to use the amount of change in the electrolyte concentration for state detection, the electrolyte solution with respect to the terms f _fast (t), f _slow (t) and f _fast (t) / f _slow (t) of the relaxation function F (t). A density change amount calculation formula for calculating the density change amount is created in advance and stored in the fixed storage unit 12. Then, an electrolyte solution concentration change amount is calculated from the concentration change amount calculation formula using the optimized relaxation function F (t), and state detection is performed by determining whether or not this satisfies a predetermined condition. Can be. By further using the amount of change in the electrolyte concentration in the state detection method of the electricity storage device, it is possible to detect the state with high accuracy.

  Another state quantity that can be used to determine the discharge capability of the electricity storage device is a change in the concentration distribution (stratification) of the electrolyte solution. An example of the concentration distribution of the electrolytic solution of the electricity storage device is shown in FIG. FIG. 22 schematically shows a state in which the stratification 94 is formed by changing the concentration distribution of the electrolytic solution 93 around the positive electrode 91 and the negative electrode 92. In the electricity storage device, the concentration distribution of the electrolytic solution changes with charge / discharge, and a stratification 94 as shown in the figure is formed. In this stratification, the lateral stratification, which is a deviation of the concentration distribution in the lateral direction (arrow 95) with respect to the liquid surface of the electrolytic solution, and the concentration distribution in the vertical direction (arrow 96) with respect to the liquid surface of the electrolytic solution. There is vertical stratification that is biased. This change in stratification occurs as the electrolyte concentration changes due to charge / discharge, and it takes time to stabilize after stopping the charge / discharge, similar to the change in electrolyte concentration.

Therefore, in order to use the stratification change amount for state detection, the stratification change with respect to the terms f _fast (t), f _slow (t) and f _fast (t) / f _slow (t) of the relaxation function F (t) A stratification change amount calculation formula for calculating the amount is created in advance and stored in the fixed storage unit 12. Then, the stratification change amount is calculated from the stratification change amount calculation formula using the optimized relaxation function F (t), and the state detection is performed by determining whether or not this satisfies a predetermined condition. Can be. By using the amount of stratification change in the state detection method of the electricity storage device, it is possible to detect the state with high accuracy.

  As another state quantity that can be used for determining the discharge capability of the electricity storage device, there is a change in the concentration distribution bias (lateral stratification) in the lateral direction with respect to the liquid surface of the electrolytic solution. This change in lateral stratification occurs as the electrolyte concentration changes due to charging / discharging, and it takes time to stabilize after stopping the charging / discharging, similar to the change in electrolyte concentration.

Therefore, in order to use the lateral stratification change amount for state detection, the lateral stratification with respect to each term f _fast (t), f _slow (t) and f _fast (t) / f _slow (t) of the relaxation function F (t). A lateral stratification change amount calculation formula for calculating the change amount of stratification is created in advance and stored in the fixed storage means 12. Then, using the optimized relaxation function F (t), the lateral stratification change amount is calculated from the lateral stratification change calculation formula, and the state detection is performed by determining whether or not this satisfies a predetermined condition. Can be done. By using the amount of lateral stratification change in the state detection method of the power storage device, it is possible to detect the state with high accuracy.

  As another state quantity that can be used for determining the discharge capability of the electricity storage device, there is a change in the concentration distribution (horizontal stratification, vertical stratification) in the horizontal and vertical directions with respect to the liquid surface of the electrolytic solution. When this is the amount of vertical and horizontal stratification change, the amount of vertical and horizontal stratification change occurs as the electrolyte concentration changes due to charge and discharge. take time.

Therefore, in order to use the vertical / horizontal stratification change amount for the state detection, the vertical / horizontal stratification with respect to the terms f _fast (t), f _slow (t) and f _fast (t) / f _slow (t) of the relaxation function F (t). A vertical and horizontal stratification change amount calculation formula for calculating the change amount is generated in advance and stored in the fixed storage unit 12. Then, using the optimized relaxation function F (t), the vertical / horizontal stratification change amount is calculated from the vertical / horizontal stratification change calculation formula, and the state detection is performed by determining whether or not this satisfies a predetermined condition. Can be done. By using the amount of vertical and horizontal stratification change in the state detection method of the power storage device, it is possible to detect the state with high accuracy.

  Note that the description in the present embodiment shows an example of the state detection method of the power storage device according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the power storage device state detection method in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

1: storage battery 2: charging means 3: load 4: input means 5: control device 10: state detection system 11: arithmetic device 12: fixed storage means 13: temporary storage means 14: timer 15: state output means

Claims (21)

A method for detecting the state of an electricity storage device,
When the power storage device stops charging / discharging and reaches a state satisfying a predetermined stability condition, the voltage of the power storage device is set as a stable voltage at stop, and time t has elapsed since the power storage device stopped charging / discharging When the amount of change from the stable voltage at the time of stop is the amount of change in voltage at the time of stop,
A relaxation function F (t) for calculating the amount of voltage change at the time of stop is created in advance as a function of a predetermined state quantity of the power storage device,
Measure the voltage at the end of charging just before stopping the charging of the electricity storage device, or the voltage at the end of discharging just before stopping the discharge,
Measure the voltage after the charging or discharging of the electricity storage device,
The relaxation function F (t) is optimized by calculating the voltage change amount at the time of stoppage from the voltage measurement value,
Estimating the state quantity from the optimized relaxation function F (t);
A method for detecting a state of an electricity storage device, comprising: determining a discharge capability (COD) of the electricity storage device using the voltage at the end of discharge or the voltage at the end of charge and the estimated state quantity. The relaxation function F (t) is a reaction function relaxation function fi (t) (i = 1 to m) of 2 or more (assumed to be m) created in advance corresponding to the reaction rate inside the electricity storage device. Is represented by a linear combination of
The relaxation function fi (t) (i = 1 to m) for each reaction rate is optimized by separating the amount of change in voltage at stop calculated from the voltage measurement value into components corresponding to the reaction rate. The state detection method of the electrical storage device of Claim 1 characterized by the above-mentioned. The power storage device is determined to have stopped charging / discharging when the current due to the charge / discharge is small or has a constant value and the influence on the transient change inside the power storage device is limited within a predetermined range. The state detection method of the electrical storage device of Claim 1 or 2. Create in advance a voltage correction amount to correct the voltage change due to the current,
The state detection method for an electricity storage device according to claim 3, wherein the relaxation function F (t) is optimized using a voltage obtained by adding the voltage correction amount to the voltage measurement value. Calculate the remaining capacity increase / decrease amount (ΔSOC) at the time of charge / discharge stop from the integrated current value obtained by integrating the current during charge / discharge immediately before the charge / discharge stop, and add the remaining capacity increase / decrease amount to the remaining capacity at the previous charge / discharge stop. And calculate the remaining capacity (SOC) at the time of the current charge / discharge stop,
5. The COD is determined based on the state quantity estimated from the discharge end voltage or the charge end voltage, the relaxation function F (t), and the SOC. 6. The state detection method of the electrical storage device of one term | claim. Create in advance a charging efficiency calculation formula with the predetermined state quantity and the charging end voltage as variables,
The SOC at the time of stopping charging / discharging is calculated by substituting the state quantity calculated using the relaxation function F (t) and the voltage at the end of charging into the charging efficiency calculation formula, and the remaining charge. 6. The method for detecting a state of an electricity storage device according to claim 5, wherein the calculation is performed by correcting the amount of increase / decrease in capacity. The method for detecting a state of a power storage device according to any one of claims 1 to 6, wherein the state quantity is a remaining capacity of the power storage device. The state detection method for an electricity storage device according to any one of claims 1 to 6, wherein the state quantity is a degree of deterioration (SOH) of the electricity storage device. The relaxation function F (t) has a component f _fast (t) with a fast relaxation rate and a component f _slow (t) with a _slow relaxation rate,
Reference values of the f _fast (t), the f _slow (t), and the ratio f _fast (t) / f _slow (t) are prepared in advance.
The f _fast (t), the f _slow (t) and the f _fast (t) / f _slow (t) calculated from the optimized F (t) and the respective reference values are used. The method for detecting a state of an electricity storage device according to any one of claims 1 to 8, wherein COD is determined. The state quantity is a deterioration degree SOH of the electricity storage device,
10. The degree of deterioration is calculated using the f _fast (t), the f _slow (t), the f _fast (t) / f _slow (t), and the respective reference values. The state detection method of the electrical storage device of description. Create a high-speed transient change correction formula that uses the remaining capacity and the voltage at the end of charging as variables in advance.
Substituting the remaining capacity at the time of stopping charging and discharging and the voltage at the end of charging into the fast transient change correction amount calculation formula to calculate a correction amount for the f _fast (t), and the f corrected by the correction amount The power storage device state detection method according to claim 10, wherein the degree of deterioration is calculated using _fast (t). Concentration change for calculating a concentration change amount of the electrolytic solution of the electricity storage device with respect to the f _fast (t), the f _slow (t), and the f _fast (t) / f _slow (t) of the relaxation function F (t) Create a quantity calculation formula in advance,
10. The electricity storage device according to claim 9, wherein a concentration change amount of the electrolytic solution is calculated from the concentration change calculation formula using the optimized relaxation function F (t) and used as the state amount. State detection method. The bias (stratification) change amount of the concentration distribution of the electrolytic solution of the electricity storage device is defined as the stratification change amount, and the f _fast (t), the f _slow (t), and the f _fast (t) of the relaxation function F (t). t) / f _slow (t) The stratification change amount calculation formula for calculating the stratification change amount with respect to (t) is created in advance,
10. The electricity storage device according to claim 9, wherein the stratification change amount is calculated from the stratification change amount calculation formula using the optimized relaxation function F (t) and used as the state quantity. State detection method. The amount of change in the concentration distribution bias (lateral stratification) in the lateral direction with respect to the liquid level of the electrolyte solution of the electricity storage device is defined as the lateral stratification change amount, and the f _fast (t) of the relaxation function F (t), Creating in advance a lateral stratification variation calculation formula for calculating the lateral stratification variation for the f _slow (t) and the f _fast (t) / f _slow (t);
10. The lateral stratification change amount is calculated from the lateral stratification change amount calculation formula using the optimized relaxation function F (t) and used for the state quantity. A method for detecting the state of an electricity storage device. The amount of change in concentration distribution in the horizontal and vertical directions (horizontal stratification, vertical stratification) with respect to the electrolyte surface of the electricity storage device is defined as the vertical and horizontal stratification change amount, and the relaxation function F (t) A vertical and horizontal stratification change amount calculation formula for calculating the vertical and horizontal stratification change amount with respect to the f _fast (t), the f _slow (t), and the f _fast (t) / f _slow (t) is created in advance.
The horizontal stratification change amount and the vertical stratification change amount are calculated from the vertical / horizontal stratification change calculation formula using the optimized relaxation function F (t) and used for the state quantity. The state detection method of the electrical storage device of Claim 9. The relaxation function F (t) is further created in advance as a function of the temperature of the electricity storage device,
The method for detecting the state of an electricity storage device according to any one of claims 1 to 15, wherein the temperature of the electricity storage device is measured and used for calculating the relaxation function F (t). The stable voltage at the time of stop is a stable OCV, and the OCV change amount is calculated by subtracting the stable OCV calculated from a stable OCV calculation formula created in advance from the voltage measurement value,
The state detection method of the electrical storage device according to any one of claims 1 to 16, wherein the OCV change amount is set as the stop-time voltage change amount. 18. The state quantity is calculated by estimating a state quantity for each reaction rate from the relaxation function fi (t) for each reaction rate and summing up the state quantities. The state detection method of the electrical storage device of description. The dependence on the temperature T of the electricity storage device is defined as fi ^ref (t), SOC ^ref , and SOHi ^ref for the reaction rate relaxation function fi (t), the SOC, and the SOH for each reaction rate in a predetermined state, respectively. Is G (T), the relaxation rate function fi ⁿ (t) for each reaction rate after the completion of the nth charge / discharge is
fi ⁿ (t) = fi ^ref (t) * {SOC ⁿ / SOC ^ref }
* {SOHi ⁿ / SOHi ^ref } * g (T) (Formula 1)
(Wherein, Sohi ⁿ is for each of the reaction rate SOH)
The state detection method for an electricity storage device according to any one of claims 1 to 18, characterized by: Measure the voltage and current of the electricity storage device,
When it is determined from the current or a predetermined charge / discharge stop signal that the electricity storage device has stopped charging / discharging,
The amount of voltage change at the time of stop corresponding to the elapsed time from the charge / discharge stop is calculated from the voltage measurement value,
Optimize the relaxation rate fi (t) for each reaction rate corresponding to the reaction rate having a time constant shorter than the elapsed time, using the voltage change amount at the time of stoppage,
For the reaction rate relaxation function fi (t) corresponding to the reaction rate longer than the time constant, the immediately preceding one is used, and the optimized relaxation rate per reaction rate fi (t) and the optimized The state detection method for an electricity storage device according to claim 2, wherein the state quantity is estimated from a voltage at the end of discharging and a voltage at the end of charging. 21. The stable voltage at the time of stopping is the voltage when the voltage after stopping charging / discharging of the power storage device becomes a fluctuation amount of 5 mV or less per hour. The state detection method of the electrical storage device of description.

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