JP4897976B2 - Method and apparatus for detecting state of power storage device - Google Patents

Description

  The present invention relates to a state detection method and apparatus for a power storage device, and more particularly to a state detection method and apparatus related to the discharge capability of a power storage device.

  In recent years, there has been an increasing need for power storage devices. For example, automobiles are equipped with many electrical devices that operate by receiving power supply from a battery, which is an electrical device, and the importance of batteries is increasing. In recent years, by-wire has progressed, and safety-related parts represented by electric brakes (EPB) have been electrically controlled. In addition, along with energy saving and carbon dioxide emission regulations, it is required to secure an idling stop function and a restart capability at a short stop at an intersection or the like.

  In fields other than automobiles, for example, in order to promote the use of natural energy such as solar power generation and wind power generation, power storage devices are used for leveling generated power and storing surplus power. Furthermore, the power storage device is also used as a backup power source such as a stabilized power source and an auxiliary power source for supplying power to an electric device during a power failure. As such an electricity storage device, a device that accompanies movement of an electrolyte such as a secondary battery or a capacitor is used. In order to be able to use an electricity storage device stably, it is necessary to be able to detect the state thereof with high accuracy so that problems such as insufficient charging can be solved at an early stage.

  In general, under the condition that the power storage device is sufficiently stable after stopping charging and discharging, a 1: 1 as indicated by reference numeral 81 in FIG. 7 is present between the open-circuit voltage (OCV) and the remaining capacity (SOC: State of charge). There is a relationship corresponding to 1. However, such a 1: 1 relationship is obtained under stable conditions such as in a laboratory. For example, in the case of a storage battery containing an electrolytic solution, the electricity storage device after charging / discharging is an ion generation / extinction reaction on the surface of the electrode plate due to an electrochemical reaction, and the movement of ions due to diffusion or convection of the electrolytic solution. Each is affected. 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 power storage medium, the concentration of the medium changes, so that it is also affected by ion diffusion and the like.

  When the ion concentration in such an electrolyte or electrolyte changes transiently, it takes a long time for the ion concentration to become sufficiently homogeneous, so the battery voltage within a limited measurement time. As a result of measurement, a 1: 1 relationship is not established between the OCV and the SOC. 8 and 9 are diagrams illustrating an example of a transient change in OCV when the SOC and temperature of the storage battery are constant. FIG. 8 shows that even if the SOC is constant, it takes time for the OCV (reference numeral 82) to stabilize at a constant value. Further, FIG. 9 shows the change in the OCV (reference numerals 83, 84, 85) in the storage battery when the SOH (deterioration degree, state of health) is different. Even when the discharge conditions are the same, it does not converge to the same OCV if the SOH is different.

  Such transient changes include those having a short reaction time such as ion generation and annihilation reactions and those having a fast change, and those having a slow change in electrolyte diffusion and convection. Therefore, in order to evaluate the discharge capability of the electricity storage device with high accuracy, for example, Patent Document 1 describes a method of evaluating such a transient change by dividing it into three time constant components. 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, when detecting the state of the electricity storage device after stopping charging / discharging, the transient change greatly differs depending on the previous charging / discharging history, etc., so the discharge capability etc. is determined with high accuracy by being strongly influenced by the charging / discharging history. There was a problem that it became difficult.

  For example, since a battery mounted on an automobile is repeatedly charged and discharged during vehicle operation, migration, precipitation, convection, diffusion, etc. occurring in the electrolyte in the battery vary depending on vehicle operation conditions. Therefore, the transitional change of the battery after the charge / discharge stop depends on the vehicle operating conditions up to that time, and it is impossible to create a reproducible stop state that can be regarded as the same or the same tendency. As in the state detection method described in Patent Document 1, even when the state change is detected by dividing the transient change after stopping the charge / discharge into components having different time constants, if the transient change of the battery after stopping the charge / discharge is greatly different, There is a problem that it is difficult to obtain each time constant component with high accuracy and it is difficult to detect the state of the battery with high accuracy.

  Therefore, the present invention has been made to solve these problems, and provides a state detection method and apparatus for a storage device that performs state detection by reducing the influence of charging and discharging before the storage device is stopped. With the goal.

  A first aspect of a state detection method for an electricity storage device according to the present invention is a state detection method for an electricity storage device, wherein the electricity storage device that has stopped charging / discharging is charged before state detection of a predetermined capacity, and the state detection The voltage of the electricity storage device when the time t has elapsed since the end of pre-charging is measured at a predetermined period, and the voltage from the stable voltage at the time of stoppage when the charge and discharge of the electricity storage device is stopped and becomes substantially constant The amount of change in the measured value (the amount of change in voltage at the time of stoppage) is optimally approximated by a relaxation function F (t) that is a function of a predetermined state quantity of the power storage device, and the above-mentioned optimally approximated relaxation function F (t) A state quantity is estimated, and the estimated state quantity is compared with a predetermined threshold value to determine the discharge capability of the power storage device.

  Another aspect of the method for detecting a state of an electricity storage device according to the present invention is characterized in that in the charge before state detection, the electricity storage device is charged at a 5% rated capacity.

  According to another aspect of the state detection method for an electricity storage device of the present invention, when the voltage measurement value obtained first after finishing the charge before state detection is lower than the stable voltage at the time of stop, the discharge capacity of the electricity storage device is It is characterized by determining that it has fallen.

  In another aspect of the method for detecting a state of an electricity storage device according to the present invention, the stable voltage at the time of stop is updated using the optimally approximated relaxation function F (t).

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 f _i (t) (i = 1 to m) is represented by a linear combination, and the reaction rate-based relaxation function f _i (t) (i = 1 to m) is the amount of voltage change at stop. Is optimized by separating into components corresponding to the reaction rate.

  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.

According to another aspect of the method for detecting a state of an electricity storage device of the present invention, the relaxation function f _i (t) for each reaction rate, the remaining capacity, and the degree of deterioration for each reaction rate in a predetermined reference state are represented by f _i ^ref ( t), SOC ^ref , and SOH _i ^ref, and G (T) as the dependence of the electricity storage device on temperature T, the relaxation function f _{i for} each reaction rate optimally approximated in the n period of the voltage measurement ⁿ (t) has the following relationship with the remaining capacity SOC ⁿ estimated in the n-th cycle and the degradation rate SOH _i ^{n for} each reaction rate: f _i ⁿ (t) = f _i ^ref ( t) * {SOC ⁿ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref } * G (T)
It is characterized by that.

  Another aspect of the method for detecting a state of an electricity storage device according to the present invention is characterized in that another state detection is performed by performing pulse discharge on the electricity storage device before performing the pre-state detection charging.

  Another aspect of the method for detecting a state of an electricity storage device according to the present invention is characterized in that impedance measurement of the electricity storage device is performed to perform another state detection before performing the pre-state detection charging.

  A first aspect of the state detection device for an electricity storage device of the present invention is a state detection device for an electricity storage device configured to be rechargeable using an internal charger controlled by a control unit, and includes a state detection mode start signal. A signal input means for inputting; an output display means for outputting predetermined information to the outside; a measuring means for measuring the voltage of the power storage device; and a switch for state detection mode, the control means, the signal input means A state detection unit connected to the output display unit and the measurement unit, and when the state detection unit inputs the state detection mode start signal from the signal input unit, before the state detection to the power storage device Stop when the voltage of the electricity storage device at the elapsed time t after charging is input from the measurement means and the charge / discharge of the electricity storage device is stopped and becomes substantially constant The amount of change of the voltage measurement value from the stable voltage (voltage change amount at the time of stoppage) is optimally approximated by a relaxation function F (t) that is a function of a predetermined state quantity of the power storage device, and the optimally approximated relaxation function F The state quantity is estimated from (t), the estimated state quantity is compared with a predetermined threshold value to determine the discharge capability of the power storage device, and the determination result is output to the output display means. .

  In another aspect of the state detection device for a power storage device according to the present invention, the state detection unit outputs a predetermined request signal to the control unit, and the control unit controls the internal charger. It is characterized by performing.

  Another aspect of the state detection device for a power storage device of the present invention is characterized in that the pre-state detection charging is performed by connecting an external charger to the power storage device.

  According to the present invention, by charging a power storage device with a predetermined capacity before the state detection, the state detection is performed by reducing the influence of charging / discharging before the stop, so that the discharge capacity of the power storage device can be increased with high accuracy. It is possible to provide a storage device state detection method and apparatus that can be determined.

It is a flowchart explaining the outline of the state detection method of the electrical storage device which concerns on the 1st Embodiment of this invention. It is a block diagram of the state detection apparatus of the electrical storage device which concerns on 1st Embodiment. It is a graph which shows the change of the electric current by the charge / discharge in driving | operation, and charge before state detection, and a voltage. It is a flowchart explaining the process after charge before a state detection is complete | finished after a state detection mode is requested | required. It is a flowchart explaining a process when state detection mode is materialized. It is a flowchart explaining the outline of the state detection method of the electrical storage device which concerns on other embodiment of this invention. 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.

  A power storage device state detection method and apparatus 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 of the present invention, a state detection mode for appropriately detecting the state of the electricity storage device is provided in order to appropriately maintain the discharge capability of the electricity storage device. The state detection mode is a system that includes an electricity storage device.For example, when the operation is stopped and charging / discharging of the electricity storage device is stopped, or when a considerable time has elapsed after the charging / discharging is stopped, It is executed by maintenance personnel. When the state detection mode is requested for the power storage device, the state of the power storage device is detected with high accuracy.

  Hereinafter, the state detection method and state detection device of the power storage device of the present invention will be described by taking a battery mounted on the vehicle as an example of the power storage device. However, the contents described below are not limited to in-vehicle batteries, but can be similarly applied to power storage devices used for photovoltaic power generation, wind power generation, and the like, and power storage devices used for backup power sources such as a stabilized power source and an auxiliary power source. Is.

  A power storage device state detection method and apparatus according to a first embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a flowchart for explaining an outline of a state detection method for a power storage device according to the present embodiment, and FIG. 2 is a block diagram of a state detection apparatus for the power storage device according to the present embodiment.

  The state detection device 100 according to the present embodiment is mounted on the vehicle 10 and detects the state of the power storage device (battery) 11. The signal input unit 101, the output display unit 102, the measurement unit 103, and the state detection unit 110. It has. A load 12 such as an in-vehicle electric device is connected to the battery 11, and an in-vehicle charger 14 such as an alternator is further connected. The signal input means 101 is used for inputting a signal (hereinafter referred to as a state detection mode start signal) for a user such as a driver to request the state detection mode, and the output display means 102 is used for the state detection mode. This is used to notify the user of the result of the above. Since both the signal input means 101 and the output display means 102 are used by the driver, it is preferable to provide them in the driver's seat or in the vicinity thereof.

  The state detection unit 110 inputs measurement values such as the voltage and current of the battery 11 from the measurement unit 103, and performs processing for detecting the state of the battery 11 with high accuracy using the measurement values. In addition, the state detection unit 110 includes a state detection mode switch 111. Instead of inputting the state detection mode start signal from the signal input unit 101, the state detection mode switch 111 is turned on to detect the state. A mode start signal is output to the state detection unit 110. The state detection mode switch 111 is provided so that a maintenance staff or the like can quickly detect the state of the battery 11 during maintenance such as during periodic inspection.

  The state detection unit 110 is configured to cause the battery 11 to be charged with a predetermined capacity (hereinafter referred to as pre-state detection charging) before performing state detection. That is, when the state detection unit 110 requests the control unit 13 to charge the battery 11 before detecting the state, the control unit 13 starts the engine and operates the on-vehicle charger 14, thereby charging the battery 11 with a predetermined capacity. Control to make it happen. Alternatively, maintenance personnel or the like can perform charging before detecting the state of the battery 11. In this case, a maintenance person or the like connects the external charger 20 to the battery 11 and charges it before detecting the state. The state detection unit 110 is configured to detect the state of the battery 11 after the on-vehicle charger 14 or the external charger 20 is charged before the state detection. A communication bus such as LIN (Local Interconnect Network) or CAN (Controller Area Network) is used as a communication unit between the state detection unit 110 and the signal input unit 101, the output display unit 102, the measurement unit 103, and the control unit 13. Can be used.

  Next, an outline of the state detection method of the present embodiment will be described using the flowchart shown in FIG. When performing the state detection of the battery 11 using the state detection device 100 of the present embodiment, first, a state detection mode start signal is input to the state detection unit 110 (step S1). Thereby, in the state detection part 110, it is determined whether the predetermined state detection permission conditions are satisfied (step S2). This condition detection permission condition includes that at least the battery 11 has stopped charging / discharging.

  If it is determined in step S2 that the state detection permission condition is satisfied, the state detection mode is set to ON in step S3, and the battery 11 is charged before state detection in the next step S4. When the pre-state detection charging is completed, the state detection unit 110 detects the state of the battery 11 (step S5). As the state detection, for example, the remaining capacity SOC of the battery 11 can be estimated, and the discharge capacity of the battery 11 can be determined based on this. When the discharge capability of the battery 11 is determined by the state detection process, the result is output to the output display means 102 and notified to the user, maintenance personnel, etc. (step S6). On the other hand, if it is determined in step S2 that the state detection permission condition is not satisfied, the process ends without performing the processes in steps S3 to S6.

  Below, the state detection method of the battery 11 performed in the state detection part 110 is demonstrated. Since the transient change after the charge / discharge stop of the battery 11 includes reaction processes with different speeds, in order to determine the discharge capability of the battery 11 after the charge / discharge stop with high accuracy, the state change for each reaction speed. It is better to detect the state using a method that can evaluate the above. For example, the battery voltage change ΔV (t) after stopping charging / discharging is expressed by the following equation using a function (hereinafter referred to as a relaxation function) F (t) consisting of m polynomials depending on the difference in reaction rate. Can be expressed as

ΔV (t) = F (t)
= F ₁ (t) + f ₂ (t) +... F _m (t) = Σf _i (t) (1)
Here, the voltage change amount ΔV (t) includes the voltage measurement value V _mes (t) when the time t has elapsed since the completion of the pre-state detection charging, and a sufficient time (for example, 20 hours) after the charge / discharge stop. It represents the difference from the stable voltage at the time of stopping (hereinafter referred to as OCV _{20 hr} ) when it becomes substantially constant after elapse.
_{ΔV (t) = V mes (} t) -OCV 20hr (2)
In the present embodiment, state detection is performed using the above equation.

In the above relaxation function F (t), each term f _i (t) represents the contribution to the voltage change of the relaxation process with different reaction rates of the battery 11, and hereinafter, the relaxation function for each reaction rate f _i (t ). Each f _i (t) is a function depending on the deterioration degree SOH, which is the state quantity of the battery 11, the remaining capacity SOC (ion concentration), and the temperature T. ΔV (t) is calculated from the voltage measurement value V _mes (t), and the equation (1) is optimized with ΔV (t) calculated from the voltage measurement value V _mes (t). f _i (t) can be determined.

In the state detection method of this embodiment, the voltage measurement value of the battery 11 is input at a predetermined cycle after the end of the pre-state detection charging, and the relaxation function F (t) is optimized every time the voltage measurement value is input. It has been updated. When the relaxation function for each reaction rate when optimized using the voltage measurement value measured for the nth time is f _i ⁿ (t), f _i ⁿ (t) can be expressed as the following equation.
f _i ⁿ (t) = f _i ^ref (t) * {SOC ⁿ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref } * G (T) (3)
Here, f _i ^ref (t), SOC ^ref , and SOH _i ^ref respectively represent a relaxation function for each reaction rate, a remaining capacity SOC, and a deterioration degree SOH for each reaction rate in a predetermined reference state, and G (T) Represents the dependence on the temperature T of the electricity storage device. From equation (3), it is possible to calculate the residual capacity SOC ⁿ and each reaction rate degradation degree SOH _i ⁿ is estimated using the n-th voltage measurement. The discharge capacity of the battery 11 can be determined from the SOC ⁿ . Further, the respective reaction rate degradation degree SOH _i ⁿ from degradation degree SOH obtained by integrating the total reaction rate, it is possible to determine the deterioration degree of the battery 11.

  In order to optimize the relaxation function F (t) shown in Equation (1) with high accuracy, in a reproducible state in which transient changes at the time of state detection can always be regarded as equivalent or have the same tendency. Preferably there is. Therefore, in the method for detecting the state of the battery 11 according to the present embodiment, the state of charge / discharge is shifted to a reproducible state as much as possible before the state is detected, and then the state is detected. In order to shift the charge / discharge state before the start of state detection to a reproducible state as much as possible, in this embodiment, charging of a predetermined capacity (charging before state detection) is performed in step S4 of FIG. State detection is performed by measuring changes and the like.

  In order to cancel the influence of the electrophoresis accompanying the discharge among the electrophoresis of the electrolytic solution accompanying the charging / discharging during the operation of the vehicle, as an appropriate state-precharging charge capacity for shifting the battery 11 to the reproducible state. A sufficient capacity is preferable. As a result, the effect of the pre-state detection charging due to the discharge during vehicle operation can be reduced, and the voltage change associated with the charge polarization can be measured during the state detection. In the following, an appropriate capacity for charging before state detection will be described for an automobile battery.

  In actual driving of a car, the charge / discharge capacity changes arbitrarily and frequently, so it is conceivable to measure and accumulate the charge / discharge capacity during driving and determine the charge capacity before state detection based on this. It is done. However, in the method of integrating the charge / discharge capacity during traveling, a charge / discharge capacity with high accuracy cannot always be obtained, and it is difficult to determine an appropriate charge capacity when shifting to the state detection mode. In addition, if the system shifts to the state detection mode after a large amount of discharge has been performed, such as when idling stops are repeatedly performed, the required capacity for charging before state detection may increase. There is a problem that the time required for the process becomes longer.

  Therefore, in the state detection method of the present embodiment, rather than determining the capacity of charge before state detection using the accumulated charge and discharge during traveling, the transient change during charging is examined in advance for each target battery, Based on this, the pre-state detection charge capacity is determined in advance. As an example, in the case of a vehicle equipped with a battery 55B24 (36 [Ah]) manufactured by Furukawa Battery, when the vehicle travels normally for about 1 to 2 hours, the charge / discharge capacity (ΔSOC) of the traveling battery ( (Absolute value) is 0.5% or less.

  Therefore, by setting the capacity for charging before state detection to a capacity sufficiently larger than the charge / discharge amount at the time of traveling, the influence of charging / discharging before shifting to the state detection mode can be sufficiently reduced. As a result, in the state detection method of the present embodiment, the battery state at the time of state detection is governed by a transient change caused by the charge before state detection, so it can be said that the state is a reproducible transient state. . How the transient change of the battery after performing the charge before the state detection changes depending on the magnitude of the charge / discharge capacity at the time of the last traveling will be described with reference to FIG. Fig. 3 shows changes in battery current and voltage during operation detection from stop to stop, and how transient changes change depending on the magnitude relationship between charge / discharge capacity during operation and charge capacity before detection. It is the graph which showed typically what to do. Here, the charging capacity before state detection is set to 5% of the rated capacity.

  FIG. 3A shows changes in current and voltage when the pre-state detection charge capacity is larger than the charge / discharge capacity during operation, and FIG. 3B shows the charge / discharge capacity and state detection during operation. FIG. 3 (c) shows changes in current and voltage when the charge / discharge capacity during operation is larger than the charge capacity before state detection. In the case where the pre-state detection charge capacity shown in FIG. 3A is larger, the charge / discharge capacity during operation is set to 1% or less. In this case, the influence of charging / discharging during operation is reduced by the pre-state detection charging, and as a result, the voltage change after the pre-state detection charging monotonously decreases and converges to a stable voltage.

  In addition, assuming that the charge / discharge capacity during operation and the charge capacity before state detection shown in FIG. 3B are approximately the same, the charge / discharge capacity during operation is set to 1% to 5%. Also in this case, the influence of charging / discharging during operation can be reduced by the pre-state detection charging, and the voltage change after the pre-state detection charging decreases monotonously to a stable voltage as in FIG. Shows a tendency to converge. Furthermore, when the charge / discharge capacity during operation shown in FIG. 3 (c) is larger than the charge capacity before state detection, the voltage tends to monotonously increase even after the completion of charge before state detection. , (B) shows a completely different tendency.

  Charging / discharging capacity during vehicle travel is usually about 1% or less, and when the pre-state detection charge capacity is 5%, the effect of charge / discharge polarization due to charge / discharge during normal vehicle travel is sufficiently reduced. can do. As a result, in the state detection after performing the pre-state detection charging, the discharge capacity is detected based on the transient change as shown in FIGS. 3A and 3B due to the 5% capacity charging. By using a function form that can optimally approximate a transient change due to charging of 5% capacity as the relaxation function F (t) of Equation (1), state detection using the relaxation function F (t) can be performed with high accuracy. Can be done.

  On the other hand, when the charge / discharge capacity during operation as shown in FIG. 3 (c) is larger than the charge capacity before state detection, a voltage lower than the stable voltage is measured. It is possible to notify a user or the like that the ability is reduced. As an example in which the discharge capacity during operation increases, there is a case where the operation is stopped after idling stop is repeatedly performed in a short time. The voltage measurement value becomes lower than the stable voltage in addition to the case where the amount of discharge during operation is particularly large, the deterioration of the battery 11 or the case where the battery 11 has been left for a long time. Even in such a case, a capacity drop (capacity shortage) or an increase in deterioration can be detected by the state detection method of the present embodiment.

  It should be noted that the charging capacity before state detection can be set to a different value depending on what type of driving is targeted for normal vehicle driving, and also considers the size, characteristics, etc. of the battery installed in the vehicle. It is better to decide. For example, in the case of setting the capacity for state pre-charge detection for discharge due to idling stop, it is preferable to set a charge capacity that is equal to or greater than the capacity discharged at idling stop. By performing charging larger than the discharge capacity during operation, state detection can be performed in a transient state in which the voltage at the time of state detection decreases monotonously as shown in FIGS. it can.

  The state detection method according to the present embodiment, which has been outlined with reference to FIG. 1, will be described in more detail with reference to FIGS. FIG. 4 is a flowchart for explaining the processing from when the state detection mode is requested until the pre-state detection charging ends. FIG. 4A shows a flow of processing when a driver or the like inputs a state detection mode start signal from the signal input means 101, and FIG. 4B shows a state detection mode switch by a maintenance person or the like. The flow of processing when 111 is turned on is shown.

  In either case of inputting a state detection mode start signal from the signal input means 101 or turning on the state detection mode switch 111, there is a possibility that the signal is input by an erroneous operation. Therefore, FIG. 4A describes the flow of processing when configured to prevent an erroneous operation, and FIG. 4B illustrates the flow of processing when the prevention of erroneous operation is not considered. However, FIG. 4B can be configured so as to prevent an erroneous operation in the same manner as FIG. 4A, and the erroneous operation preventing process can be omitted in FIG. 4A.

  In FIG. 4A, when a state detection mode start signal is input from the signal input unit 101 (step S11), this signal is output to the state detection unit 110. When the state detection mode start signal is input, the state detection unit 110 displays a confirmation message on the output display unit 102 to confirm that the state detection is requested (step S12). Based on the confirmation message, for example, when a confirmation signal is input from the signal input means 101 (step S13), it is next determined whether a predetermined state detection permission condition is satisfied (step S14).

  As said condition detection permission conditions, it is requested | required that the battery 11 is not charging / discharging at least. As a method for determining that the battery 11 is not charging / discharging, for example, it is confirmed that the vehicle 10 is in a stopped state (the key switch is in the OFF position). Further, whether the state detection unit 110 and the peripheral device can communicate with each other, whether the measurement value from the measurement unit 103 indicates a value within the normal range, or can start the engine and operate the in-vehicle charger 14 normally. If any of them is abnormal, the state detection permission condition may not be established.

  If the result of determination in step S14 is that the condition detection permission condition is satisfied, the condition detection mode is set to ON in step S15. At this time, it may be displayed on the output display means 102 that the state detection mode is turned on. In step S16, the on-vehicle charger 14 is used to cause the battery 11 to start pre-state detection charging. The pre-state detection charging using the in-vehicle charger 14 is performed by the state detection unit 110 requesting the control unit 13 to charge a predetermined capacity, and the control unit 13 starts the engine and operates the in-vehicle charger 14. .

  On the other hand, if the state detection permission condition is not satisfied in the determination in step S14, the process ends without performing the processes in steps S15 and S16. At this time, which of the state detection permission conditions is not satisfied may be displayed on the output display means 102.

  Next, a flow of processing for starting state detection by turning on the state detection mode switch 111 will be described with reference to FIG. When the maintenance staff or the like turns on the state detection mode switch 111 (step S21), a state detection mode start signal is output to the state detection unit 110. When the state detection unit 110 receives the state detection mode start signal, the state detection unit 110 next determines whether a predetermined state detection permission condition is satisfied (step S22). The condition detection permission condition can be the same as in the case of FIG.

  If the condition detection permission condition is satisfied as a result of the determination in step S22, the state detection mode is set to ON in step S23, and in step S24, before the state detection is performed on the battery 11 using the external charger 20. Start charging. Charging by the external charger 20 is performed by maintenance personnel or the like. Therefore, in step S24, a charge start request message is displayed on the output display means 102, and it is preferable that a maintenance person or the like confirms this to perform charging. In addition, when charging of a predetermined capacity is completed, maintenance personnel or the like operate the state detection mode switch 111 or input a signal for notifying that pre-state detection charging has ended from the signal input unit 101. Good.

  On the other hand, if the state detection permission condition is not satisfied in the determination in step S22, the process ends without performing the processes in steps S23 and S24. At this time, which of the state detection permission conditions is not satisfied may be displayed on the output display means 102.

  Next, the flow of processing when the state detection mode is established will be described with reference to FIG. The process shown in FIG. 5 is executed at a predetermined cycle. First, in step S31, it is determined whether the state detection mode is on. As a result, if the state detection mode is on, the process proceeds to step S32. If the state detection mode is off, the process ends without performing the following processing. In the next step S32, it is determined whether or not the condition detection permission condition is satisfied. The confirmation of the condition detection permission condition is always performed during the condition detection mode period. As a result, when the state detection permission condition is satisfied, the process proceeds to the next step S33, and when the state detection permission condition is not satisfied, the process proceeds to step S39. In this case, the output display unit 102 may display which of the state detection permission conditions is not satisfied.

  In step S33, it is determined whether or not the pre-state detection charging is finished. When the pre-state detection charging is performed using the in-vehicle charger 14, it can be determined by confirming whether the charging is completed with respect to the control means 13. Alternatively, the determination can be made based on the elapsed time from the start of charging. Further, when the pre-state detection charging is performed using the external charger 20, the determination is made by inputting a charge end signal from the state detection mode switch 111 or the signal input unit 101. If the result of determination in step S33 is that pre-state detection charging has been completed, processing proceeds to the next step S34. On the other hand, if it is determined that the pre-state detection charging has not ended, the processing ends without performing the following processing.

In step S34, the current voltage measurement value V _mes (t) is input using the measurement means 103. In step S35, the relaxation function F (t) is input using the voltage measurement value V _mes (t) input so far. To optimize. In the next step S36, the discharge capacity of the battery 11 is estimated using the optimized F (t). As the discharge capacity, for example, the estimated value of the stable voltage OCV _20hr at the time of stoppage is updated from the equations (1) and (2), and the SOC obtained from the relationship between the OCV _20hr and the SOC as shown in FIG. 7 is used. it can. In step S37, the SOC estimated in this way is temporarily stored in a predetermined storage unit.

  In step S38, it is determined whether the elapsed time t from the start of state detection has reached a predetermined time. If the elapsed time t has reached the predetermined time, the process proceeds to step S39. On the other hand, if the elapsed time t has not reached the predetermined time, the process ends without performing the following processing. In step S39, the discharge capability temporarily stored in step S37 is read, and when this is equal to or greater than a predetermined threshold, it is determined that the discharge capability is normal, and when it is less than the predetermined threshold, it is determined that the discharge capability is abnormal. In step S40, the result of determining the discharge capacity is output to the output display means 102. Further, in step S41, the state detection mode is turned off and the process is terminated.

  Another embodiment of the method for detecting the state of an electricity storage device of the present invention will be described below with reference to the flowchart shown in FIG. In the state detection method of the present embodiment, state detection by pulse discharge (step S51) and state detection by impedance measurement (step S52) are performed before performing state detection of the battery 11 in the state detection mode. In the state detection by pulse discharge, the current and voltage when the battery 11 is pulse-discharged are measured, and the discharge capacity and the deterioration state of the battery 11 are detected based on the current and voltage. In the state detection by impedance measurement, the internal impedance of the battery 11 is estimated from the measured values of current and voltage, and the deterioration state of the battery 11 is detected based on this.

  The state detection method according to the state detection mode of the present invention may be performed independently as in the first embodiment, or is combined with state detection by pulse discharge and state detection by impedance measurement as in the present embodiment. Can also be done. In addition, it is not always necessary to combine state detection by pulse discharge and state detection by impedance measurement, and one of state detection by pulse discharge and state detection by impedance measurement is combined with state detection by state detection mode. Is also possible.

  In the above description, the state detection is performed immediately after the charging / discharging of the battery 11 is stopped. However, the present invention is not limited to this. For example, the state detection is performed even when the charging / discharging of the battery 11 is stopped for a long time. Can do. For example, the discharge capability of the battery 11 can be confirmed by executing the state detection mode with a frequency of about once a month. At the same time, recovery charging (5% charging) of the battery 11 can be performed safely and efficiently even when parking for a long time by charging before state detection in the state detection mode.

  In the present embodiment, as a method of performing pre-state detection charging, the control unit 13 starts the engine and operates the in-vehicle charger 14 in response to a request from the state detection unit 110 to charge the battery 11. However, instead of this, a state detection mode start signal may be input immediately before the driver finishes traveling and stops the engine. In this case, for example, charging before the state detection by the in-vehicle charger 14 can be performed immediately without stopping the engine even if the key switch is turned off, and the engine can be automatically stopped when charging is completed.

  In the above-described embodiment, the case where it is detected whether the discharge capability is secured as the state detection of the power storage device has been described. However, the present invention is not limited to this, and it is also easy to determine deterioration such as SOH. is there. Since the relaxation function F (t) also has dependency on the SOH, an equation for calculating the SOH can be derived from the relaxation function F (t). By using such an expression, it is possible to estimate the SOH and determine the deterioration state of the electricity storage device.

  As described above, according to the state detection method and state detection device of the electricity storage device of the present invention, the electricity storage device is in a reproducible transient change state by charging a predetermined capacity before performing state detection. It has migrated. As a result, it is possible to perform state detection in a reproducible transient state that can be regarded as equivalent or have the same tendency, and it is possible to detect the state of the power storage device with high accuracy. As a result, insufficient charging or failure of the power storage device can be detected at an early stage, and the reliability as a backup of vehicle operation or auxiliary equipment can be improved. Furthermore, the charging before the state detection can prevent a large capacity shortage and reduce the deterioration of the power storage device, thereby realizing stable operation of the system and extending the life of the power storage device.

  Note that the description in the present embodiment shows an example of the state detection method and apparatus of the electricity 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 and the apparatus in the present embodiment can be appropriately changed without departing from the spirit of the present invention.

10: Vehicle 11: Electric storage device (battery)
12: Load 13: Control means 14: On-vehicle charger input means 20: External charger 100: State detection device 101: Signal input means 102: Output display means 103: Measurement means 110: State detection section 111: Switch for state detection mode

Claims (13)

A method for detecting the state of an electricity storage device,
Perform charge before state detection of a predetermined capacity to the electricity storage device that has stopped charging and discharging,
Measure the voltage of the electricity storage device at a predetermined period when time t has elapsed since the completion of the pre-state detection charging,
The amount of change in the voltage measurement value from the stable voltage at the stop when the charge / discharge of the power storage device is stopped and becomes substantially constant (the amount of change in voltage at the stop) is a function of a predetermined state quantity of the power storage device. An optimal approximation with a certain relaxation function F (t),
Estimating the state quantity from the optimally approximated relaxation function F (t);
A method for detecting a state of an electricity storage device, comprising: comparing the estimated state quantity with a predetermined threshold value to determine a discharge capability of the electricity storage device. The method for detecting a state of an electricity storage device according to claim 1, wherein, in the charging before state detection, charging of the electricity storage device is performed at a 5% rated capacity. The discharge capacity of the electricity storage device is determined to be reduced when the voltage measurement value obtained first after the completion of the pre-state detection charging is lower than the stable voltage at the time of stoppage. Or the state detection method of the electrical storage device of 2. The method for detecting a state of an electricity storage device according to any one of claims 1 to 3, wherein the stable voltage at the time of stop is updated using the optimally approximated relaxation function F (t). The relaxation function F (t) is two or more (m) relaxation rate relaxation functions f _i (t) (i = 1 to m) prepared in advance corresponding to the reaction rate inside the electricity storage device. )
The relaxation function f _i (t) (i = 1 to m) for each reaction rate is optimized by separating the voltage change amount at the time of stoppage into components corresponding to the reaction rate. The state detection method of the electrical storage device of any one of 1-4. The state detection method according to any one of claims 1 to 5, wherein the state quantity is a remaining capacity (SOC) of the power storage device. The state detection method according to any one of claims 1 to 5, wherein the state quantity is a degree of deterioration (SOH) of the power storage device. The power storage device is defined as f _i ^ref (t), SOC ^ref , and SOH _i ^ref , respectively, with the relaxation function f _i (t) for each reaction rate, the remaining capacity, and the degree of deterioration for each reaction rate in a predetermined reference state. When the dependence on the temperature T is G (T), the relaxation rate function f _i ⁿ (t) optimally approximated in the n period of the voltage measurement is estimated in the n period. The remaining capacity SOC ⁿ has the following relationship with the degradation rate SOH _i ^{n for} each reaction rate: f _i ⁿ (t) = f _i ^ref (t) * {SOC ⁿ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref } * G (T) (Formula 1)
The state detection method of the electrical storage device of any one of Claims 1 thru | or 7 characterized by the above-mentioned. Before charging before the state detection,
The state detection method for an electricity storage device according to any one of claims 1 to 8, wherein another state detection is performed by performing pulse discharge on the electricity storage device. Before charging before the state detection,
The state detection method for an electricity storage device according to any one of claims 1 to 9, further comprising performing another state detection by measuring impedance of the electricity storage device. A state detection device for an electricity storage device configured to be rechargeable using an internal charger controlled by a control means,
A signal input means for inputting a state detection mode start signal;
Output display means for outputting predetermined information to the outside;
Measuring means for measuring the voltage of the electricity storage device;
A state detection mode switch, and a state detection unit connected to the control unit, the signal input unit, the output display unit, and the measurement unit;
When the state detection unit receives the state detection mode start signal from the signal input unit, the state detection unit inputs, from the measurement unit, the voltage of the power storage device at an elapsed time t after the power storage device is charged before state detection. Then, the amount of change in the voltage measurement value from the stable voltage at stop when the charge / discharge of the power storage device is stopped and becomes substantially constant (the amount of change in voltage at stop) is a function of the predetermined state quantity of the power storage device. Is optimally approximated with a relaxation function F (t), and the state quantity is estimated from the optimally approximated relaxation function F (t), and the estimated state quantity is compared with a predetermined threshold to An apparatus for detecting a state of an electricity storage device, wherein discharge capacity is determined and a determination result is output to the output display means. The power storage device according to claim 11 , wherein the charging before the state detection is performed by the state detection unit outputting a predetermined request signal to the control unit, and the control unit controlling the internal charger. State detection device. The state detection device for an electricity storage device according to claim 11 , wherein the pre-state detection charging is performed by connecting an external charger to the electricity storage device.

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