JP7634839B2 - Deterioration diagnosis method and deterioration diagnosis device - Google Patents

Description

The present invention relates to a technology for diagnosing the deterioration of a storage battery.

Technologies for diagnosing the degraded state of a storage battery are known. As one such prior art, a technology that can determine the degraded state from the circuit characteristics when the storage battery is charged and discharged is under consideration (see Patent Document 1). Unlike diagnostic technologies that perform test charging and discharging of a storage battery to diagnose the degraded state of the storage battery, this technology does not require the operation of the storage battery to be stopped. On the other hand, a technology that can quickly synthesize an equivalent circuit from the circuit characteristics when the storage battery is charged and discharged is also under consideration (see Patent Document 2).

JP 2014-149280 A JP 2013-253784 A

It is desirable to realize a technology that can determine the state of degradation of a storage battery from the circuit characteristics when the storage battery is charged and discharged, and can more accurately determine the state of degradation of the storage battery. One aspect of the disclosure of the present invention has been made in consideration of this situation, and aims to realize a degradation diagnosis method that can accurately determine the state of degradation of a storage battery from the circuit characteristics when the storage battery is charged and discharged.

The degradation diagnosis method according to one aspect of the present invention includes the steps of measuring the battery temperature, terminal current, and terminal voltage during charging or discharging of the battery, performing a transient response analysis of the battery based on the terminal current and the terminal voltage, and calculating the series resistance component of the battery at the battery temperature, correcting the series resistance component at the battery temperature to the series resistance component at a predetermined reference temperature, and diagnosing the degradation state of the battery by calculating a capacity decrease rate, which is the rate of decrease in the storage capacity of the battery relative to the storage capacity in the initial state of the battery, based on the series resistance component at the reference temperature. The transient response analysis is performed by reducing the battery to an equivalent circuit including a circuit connected in series with the series resistance component and a parallel connection circuit in which a parallel capacitance component and a parallel resistance component are connected in parallel.

The deterioration diagnosis device according to one aspect of the present invention includes a measurement unit that measures the battery temperature, terminal current, and terminal voltage during charging or discharging of the battery, an analysis unit that performs a transient response analysis of the battery based on the terminal current and the terminal voltage, and calculates the series resistance component of the battery at the battery temperature, a correction unit that corrects the series resistance component at the battery temperature to the series resistance component at a predetermined reference temperature, and a diagnosis unit that calculates a capacity decrease rate, which is the decrease rate of the storage capacity of the battery relative to the storage capacity in the initial state of the battery, based on the series resistance component at the reference temperature, and diagnoses the deterioration state of the battery. The analysis unit reduces the battery to an equivalent circuit including a circuit in which the series resistance component and a parallel connection circuit in which a parallel capacitance component and a parallel resistance component are connected in parallel are connected in series, and performs the transient response analysis.

According to the degradation diagnosis method of one aspect of the present invention, or the degradation diagnosis device of one aspect of the present invention, it is possible to accurately determine the degradation state of a storage battery from the circuit characteristics during charging and discharging of the storage battery.

1 is a functional block diagram showing a schematic configuration of a degradation diagnosis device according to a first embodiment of the present invention; 3 is a flowchart for illustrating a processing procedure of a degradation diagnosis method executed by the degradation diagnosis device according to the first embodiment of the present invention. 4 is a graph showing example waveforms of a current Ib and a voltage Vb measured by a measurement unit of the degradation diagnosis device according to the first embodiment of the present invention. 3 is an equivalent circuit of a battery applied to a transient response analysis performed by an analysis unit of the degradation diagnosis device according to the first embodiment of the present invention. 1 is a graph showing results of the series resistance component Ri calculated by transient response analysis at various temperatures T. Plots with different symbols represent results when the battery degradation state is different. 1 is a graph showing the dependency of a temperature correction coefficient A on a capacity decrease rate D. 1 is a graph showing the dependency of a temperature correction coefficient B on a capacity decrease rate D. 1 is a graph showing the dependency of a temperature correction coefficient C on a capacity decrease rate D. 1 is a graph showing plots (squares) showing the relationship between the capacity decrease rate D and the series resistance component Ri under conditions where the battery temperature T is fixed, and plots (circles) showing the relationship between the capacity decrease rate D and the corrected series resistance component Ri_st. 1 is a graph showing plots (triangles) showing the relationship between the capacity decay rate D and the series resistance component Ri, and plots (circles) showing the relationship between the capacity decay rate D and the parallel resistance component R1, under the condition that the battery temperature T is fixed. 10 is a flowchart for illustrating a processing procedure of a degradation diagnosis method executed by a degradation diagnosis device according to a second embodiment of the present invention. 4 is an example of an equivalent circuit of a battery applied to a transient response analysis performed by an analysis unit of a degradation diagnosis device according to one embodiment of the present invention.

[Embodiment 1]
<Configuration of Deterioration Diagnosis Device>
An embodiment of the present invention will be described in detail below. Fig. 1 is a functional block diagram showing a schematic configuration of a degradation diagnosis device 1 according to an embodiment of the present invention. The degradation diagnosis device 1 is a device that executes a degradation diagnosis method according to an embodiment of the present invention.

The deterioration diagnosis device 1 monitors the battery 90, which is a storage battery, i.e., a secondary battery, and performs deterioration diagnosis of the battery 90. The battery 90 is, for example, a lithium ion secondary battery. The deterioration diagnosis device 1 does not need to be a device physically contained in a single housing, so long as each of the functional blocks shown in FIG. 1 and the following description is realized.

The degradation diagnosis device 1 includes a measurement unit 10, a calculation processing unit 20, and a storage unit 30. The storage unit 30 is a memory that stores information, and may be configured as a magnetic disk, a semiconductor memory, or any other known memory device, either alone or in combination.

The measurement unit 10 has an ammeter 11 that monitors the current Ib, which is the terminal current flowing between the terminals of the battery 90. In this specification, the current Ib is expressed as a positive value when charging is performed, and the current Ib is expressed as a negative value when discharging is performed. The measurement unit 10 has a voltmeter 12 that monitors the voltage Vb, which is the terminal voltage applied between the terminals of the battery 90.

The measurement unit 10 also has a thermometer 13 that monitors the temperature T (storage battery temperature) of the battery 90. More specifically, the thermometer 13 may be configured to measure the temperature of the surface of the cell of the battery 90. Alternatively, the thermometer 13 may be configured to measure the temperature of the terminals of the battery 90.

The value of the current Ib measured by the ammeter 11 is converted from analog to digital by the AD converter 14 and transmitted to the calculation processing unit 20 as a digital signal. The value of the voltage Vb measured by the voltmeter 12 is converted from analog to digital by the AD converter 15 and transmitted to the calculation processing unit 20 as a digital signal. The value of the temperature T measured by the thermometer 13 is converted from analog to digital by the AD converter 16 and transmitted to the calculation processing unit 20 as a digital signal.

By using the measurement unit 10 having the above configuration, the degradation diagnosis device 1 can measure the temperature T (storage battery temperature), current Ib (terminal current), and voltage Vb (terminal voltage) of the battery 90 while the battery 90 is being charged or discharged.

The calculation processing unit 20 has the following functional blocks: an analysis unit 21, a correction unit 22, a diagnosis unit 23, and a control unit 24. The analysis unit 21 is a functional block that analyzes the current Ib (terminal current) and voltage Vb (terminal voltage) during charging or discharging of the battery 90 (storage battery) measured by the measurement unit 10, and calculates the series resistance component Ri at a temperature T (storage battery temperature).

The correction unit 22 is a functional block that corrects the series resistance component Ri at temperature T (storage battery temperature) calculated by the analysis unit 21 to the series resistance component Ri_st at a predetermined reference temperature Tst. The diagnosis unit 23 is a functional block that diagnoses the degradation state of the battery 90 (storage battery) based on the series resistance component Ri_st at the reference temperature Tst calculated by the correction unit 22.

The control unit 24 is a functional block that manages the calculation processing unit 20 and controls each part of the degradation diagnosis device 1. The operations performed by each functional block of the calculation processing unit 20 will be described in detail later.

<Operation of the Deterioration Diagnostic Device>
The degradation diagnosis method, which is a characteristic operation executed by the degradation diagnosis device 1, will be described in detail with reference to Figures 2 to 10. Note that when no unit is indicated on the axis of the graph in each figure, the axis is in an arbitrary unit. Figure 2 is a flowchart showing the degradation diagnosis method executed by the degradation diagnosis device 1 step by step.

At the beginning of the degradation diagnosis method, the control unit 24 acquires the current Ib, voltage Vb, and temperature T measured by the measurement unit 10 (step S1). Figure 3 is a graph showing an example of the waveform of the current Ib detected by the ammeter 11 of the measurement unit 10 and the waveform of the voltage Vb detected by the voltmeter 12. Figure 3 shows a situation in which a discharge with a large current value temporarily occurs. As shown in the figure, while the discharge is occurring, the voltage Vb gradually decreases.

Next, the control unit 24 causes the analysis unit 21 to perform a transient response analysis of the battery 90 during charging or discharging based on the acquired waveform data of the current Ib and voltage Vb. At this time, the analysis unit 21 performs a transient response analysis of the battery 90 during charging or discharging based on the waveforms of the current Ib and voltage Vb (step S2).

In the transient response analysis of the battery 90, the analysis unit 21 treats the battery 90 as an equivalent circuit shown in FIG. 4. The internal equivalent circuit between the terminals of the battery 90 is represented by a circuit in which one or more stages of an RC parallel circuit (parallel connection circuit) of a series resistance component Ri, a parallel capacitance component Cn, and a parallel resistance component Rn are connected in series, a series capacitance component Co, and an electromotive force Eo. Here, the electromotive force Eo is the open circuit voltage between the terminals of the battery 90. The symbol n in the parallel capacitance component Cn and the parallel resistance component Rn represents the index of the RC parallel circuit. When the number of stages of the RC parallel circuit is M, the index n is any natural number from 1 to M.

That is, the internal impedance between the terminals of the battery 90 is represented by a series connection of the impedance of each stage of an RC parallel circuit (parallel connection circuit) of a parallel capacitance component Cn and a parallel resistance component Rn, a series resistance component Ri, and a series capacitance component Co. In step S2, the analysis unit 21 calculates the series resistance component Ri of the battery 90 at temperature T by fitting the waveform data of the current Ib and the voltage Vb to such an equivalent circuit. Note that the number of stages M of the RC parallel circuit may be one, and in that case, the equivalent circuit is represented as shown in FIG.
The parallel resistance component Rn is also a resistance component equivalent to the reaction resistance component of the battery 90. The series capacitance component Co and the electromotive force Eo, which is the open circuit voltage, are values specific to the battery 90 that do not vary depending on the deterioration state of the battery 90, and are stored in advance in the storage unit 30. The correction unit 22 performs the fitting by referring to the values of the series capacitance component Co and the electromotive force Eo stored in the storage unit 30.

Figure 5 is a graph showing the results of the calculated series resistance component Ri at various temperatures T of the battery 90. In the deterioration diagnosis device 1, it is preferable to use the temperature immediately before charging or discharging, which is the subject of the transient response analysis, as the temperature T of the battery 90. As shown in Figure 5, it can be seen that the series resistance component Ri is highly dependent on the temperature T of the battery 90. In addition, in Figure 5, each plot with a different symbol indicates the results obtained in cases where the deterioration state of the battery 90 is different. The more the deterioration of the battery 90 progresses, the larger the series resistance component Ri becomes. In other words, the result represented by a triangle represents the most deteriorated state of the battery 90 among the three results in Figure 5.

In this specification, the deterioration state of the battery 90 is expressed as a capacity decrease rate D, which is the rate at which the storage capacity Q of the battery 90 decreases relative to the storage capacity Qo of the battery 90 in its initial state:

Here, the capacity degradation rate D is expressed in percent (%).

For each plot in Figure 5 showing different degradation states, the relationship between temperature T and series resistance Ri can be well approximated by equation (2):

The coefficients A, B, and C here are referred to as temperature correction coefficients.

Figures 6, 7, and 8 are graphs showing the dependence of temperature correction coefficients A, B, and C on capacity decline rate D, respectively. As is clear from the figures, temperature correction coefficient A is a parameter that is highly dependent on capacity decline rate D. On the other hand, temperature correction coefficient B is a parameter that is independent of capacity decline rate D, and temperature correction coefficient C has little dependence on capacity decline rate D. Therefore, in equation (2), temperature correction coefficient A is a function of capacity decline rate D, but temperature correction coefficients B and C are considered to be constants that are independent of capacity decline rate D.

As a result, when considering the series resistance component Ri_st of the battery 90 at a certain reference temperature Tst, the temperature correction coefficient A is eliminated from equation (2) and the series resistance component Ri_st at the reference temperature Tst is expressed by equation (3):

In each formula, the temperature T and the reference temperature Tst are expressed in absolute temperature.

In this way, the series resistance component Ri_st at the reference temperature Tst can be calculated from the measured series resistance component Ri at a certain temperature T, regardless of the state of deterioration of the battery 90, i.e., even if the capacity decrease rate D is unknown.

Next, the control unit 24 controls the correction unit 22 to calculate the series resistance component Ri_st at the reference temperature Tst from the series resistance component Ri calculated by the analysis unit 21 based on the acquired temperature T. That is, the correction unit 22 corrects the series resistance component Ri at temperature T to the value at the reference temperature Tst. The temperature correction coefficients B and C are values determined for each battery 90 and are stored in advance in the storage unit 30. The correction unit 22 refers to the values of the temperature correction coefficients B and C stored in the storage unit 30 and performs the correction according to formula (3) (step S3).

Next, the control unit 24 controls the diagnosis unit 23 to calculate the capacity degradation rate D of the battery 90 based on the series resistance component Ri_st at the reference temperature Tst. As described above, the capacity degradation rate D is an index that indicates the state of degradation of the battery 90, and thus, the degradation diagnosis device 1 realizes degradation diagnosis of the battery 90 (step S4).

The plots represented by squares in FIG. 9 show the relationship between the capacity loss rate D and the series resistance component Ri when the temperature T of the battery 90 is fixed at 25° C. As shown in the figure, it is understood that the capacity loss rate D is strongly dependent on the series resistance component Ri and can be well expressed by a linear equation. In other words, if the series resistance component Ri can be calculated under conditions where the temperature T is constant, the capacity loss rate D can be accurately determined. However, in reality, it is difficult to expect that the current Ib and voltage Vb will be measured under conditions where the temperature T is constant when the battery 90 is actually operated.

In addition, in FIG. 9, although the temperature T of the battery 90 at the time of measurement is different from 25°C, the reference temperature Tst is set to 25°C, and the series resistance component Ri_st at the reference temperature Tst obtained by correcting the series resistance component Ri according to the above procedure is plotted as a circle. Even in this case, it is understood that the capacity reduction rate D is strongly dependent on the corrected series resistance component Ri_st and can be well expressed by a linear equation. In other words, it is clear that the series resistance component Ri is appropriately corrected to the series resistance component Ri_st at the reference temperature Tst by the above procedure.

The capacity loss rate D can therefore be accurately estimated by the linear equation (4) using the series resistance component Ri_st at the reference temperature Tst:

Here, the constant Rio is the series resistance component at the reference temperature Tst in the initial state, and the coefficient d is referred to as the deterioration correction coefficient.

The constant Rio and the deterioration correction coefficient d are values determined for each battery 90 and are stored in advance in the memory unit 30. In step S4, the diagnosis unit 23 refers to the values of the constant Rio and the deterioration correction coefficient d stored in the memory unit 30, and calculates the capacity decrease rate D of the battery 90 from the series resistance component Ri_st at the reference temperature Tst according to equation (4).

The storage capacity Q of the battery 90 is calculated by the formulas (1) to (4).

It can be expressed as:

<Action and Effects>
According to embodiment 1, the degradation diagnosis device 1 monitors the terminal current (current Ib) and inter-terminal voltage (voltage Vb) of the battery 90 during charging or discharging, and the temperature T of the battery 90, thereby being able to calculate the capacity degradation rate D, which is an index of degradation of the battery 90, from the circuit characteristics of the battery.

Therefore, the deterioration state of the battery 90 can be diagnosed without performing a test to determine the charge capacity by discharging and fully charging the battery 90. Alternatively, the deterioration state of the battery 90 can be diagnosed without performing a test to introduce a specific current or apply a voltage to the battery 90. Therefore, according to the first embodiment, the deterioration state of the battery 90 can be diagnosed while maintaining the operation of the battery 90.

Furthermore, according to the degradation diagnosis method of embodiment 1, the temperature T of the battery 90 is measured and the circuit characteristics (series resistance component Ri) of the battery 90 are corrected, so that the strong influence of the temperature T as shown in FIG. 5 can be cancelled and the degradation state of the battery 90 can be correctly diagnosed. In particular, embodiment 1 uses a clever technique that can cancel the influence of the temperature T without being influenced by the degradation state of the battery 90 (capacity reduction rate D) as shown in formula (3), and the degradation state of the battery 90 can be accurately diagnosed.

The degradation diagnosis method of the first embodiment is based on the use of a circuit parameter called the series resistance component Ri, which can accurately predict the capacity decrease rate D, which is an index showing the degradation state of the battery 90, as shown in formula (4) and FIG. 9. Therefore, according to the degradation diagnosis method of the first embodiment, it becomes possible to accurately diagnose the degradation state of the battery 90.

Figure 10 is a graph showing the relationship between the capacity drop rate D and the series resistance component Ri or the parallel resistance component R1 (reaction resistance component) under the condition that the temperature T of the battery 90 is kept constant to eliminate the influence of the temperature T. Note that the equivalent circuit used for the transient response analysis is the equivalent circuit shown in Figure 12, in which the number of stages M of the RC parallel circuit is one stage.

As shown in FIG. 10, the capacity reduction rate D changes uniformly with respect to the series resistance component Ri, whereas there is a region where the dependency on the parallel resistance component R1 is unclear. In addition, the capacity reduction rate D is expressed by a linear equation for the series resistance component Ri, and the capacity reduction rate D can be predicted with good accuracy over a wide range of the capacity reduction rate D.

Therefore, in the first embodiment, it is understood that by representing the battery 90 with the equivalent circuit shown in FIG. 4 or FIG. 10 and extracting a specific component, the series resistance component Ri, from the resistance component, it is possible to accurately diagnose the deterioration state of the battery 90.

[Embodiment 2]
Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

Figure 11 is a flowchart showing a degradation diagnosis method executed by a degradation diagnosis device according to embodiment 2. The degradation diagnosis method according to embodiment 2 is the same as that according to embodiment 1, except that a decision step SJ is added between steps S1 and S2 to branch the flow, compared to the degradation diagnosis method according to embodiment 1 shown in Figure 2.

In step SJ following step S1, the control unit 24 determines whether the acquired temperature T is within a required range, i.e., whether the acquired temperature T is equal to or greater than the lower limit temperature T1 and equal to or less than the upper limit temperature T2. If it is determined to be within the required range (YES in step SJ), the flow proceeds to step S2. Otherwise (NO in step SJ), the flow ends.

In the degradation diagnosis method according to the second embodiment, the deterioration state of the battery 90 is diagnosed only when the acquired temperature T is within a required range, so that the degradation diagnosis can be performed more accurately. Note that the condition for the acquired temperature T to be within the required range is not limited to the above example, and the condition may be that the temperature T is equal to or higher than the lower limit temperature T1. Alternatively, the condition may be that the temperature T is equal to or lower than the upper limit temperature T2.

[Software implementation example]
The control block (particularly, the arithmetic processing unit 20) of the degradation diagnosis device 1 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software.

In the latter case, the degradation diagnosis device 1 includes a computer that executes program instructions, which are software that realize each function. This computer includes, for example, one or more processors, and a computer-readable recording medium that stores the program. The object of the present invention is achieved by having the processor read and execute the program from the recording medium in the computer.

The processor may be, for example, a CPU (Central Processing Unit). The recording medium may be a "non-transitory tangible medium" such as a ROM (Read Only Memory), as well as a tape, a disk, a card, a semiconductor memory, or a programmable logic circuit. The device may further include a RAM (Random Access Memory) for expanding the program.

The program may be supplied to the computer via any transmission medium capable of transmitting the program (such as a communication network or broadcast waves). One aspect of the present invention may also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

〔summary〕
A deterioration diagnosis method according to aspect 1 of the present invention includes the steps of measuring the battery temperature, terminal current, and terminal voltage while the battery is being charged or discharged, performing a transient response analysis of the battery based on the terminal current and the terminal voltage, and calculating the series resistance component of the battery at the battery temperature, correcting the series resistance component at the battery temperature to the series resistance component at a predetermined reference temperature, and calculating a capacity decline rate, which is the rate of decline of the storage capacity of the battery relative to the storage capacity in the initial state of the battery, based on the series resistance component at the reference temperature, to diagnose the deterioration state of the battery, wherein the transient response analysis is performed by reducing the battery to an equivalent circuit including a circuit connected in series with the series resistance component and a parallel connection circuit in which a parallel capacitance component and a parallel resistance component are connected in parallel.

The degradation diagnosis method according to aspect 2 of the present invention may be characterized in that in the step of diagnosing the degradation state of the storage battery in the above aspect 1, the capacity decrease rate is calculated from a linear equation for the series resistance component at the reference temperature.

The degradation diagnosis method according to aspect 3 of the present invention may be characterized in that in the above-mentioned aspects 1 or 2, the equivalent circuit further includes a series capacitance component connected in series to the series resistance component and the parallel connection circuit.

The degradation diagnosis method according to aspect 4 of the present invention may be characterized in that in any one of aspects 1 to 3 above, the equivalent circuit includes a circuit in which a parallel connection circuit in which a parallel capacitance component and a parallel resistance component are connected in parallel is connected in series.

The degradation diagnosis method according to aspect 5 of the present invention may further include a step of determining whether the storage battery temperature is within a predetermined range in any one of aspects 1 to 4 above, and may be characterized in that, if it is determined in the step of determining whether the storage battery temperature is within the predetermined range that the storage battery temperature is not within the predetermined range, the step of diagnosing the degradation state of the storage battery is not executed.

The degradation diagnosis method according to aspect 6 of the present invention may be characterized in that, in any one of aspects 1 to 5 above, in the step of correcting the series resistance component at the battery temperature to the series resistance component at a predetermined reference temperature, when the battery temperature is expressed as T [K], the reference temperature is expressed as Tst [K], and the series resistance component at the battery temperature T is expressed as Ri, the series resistance component Ri_st at the reference temperature Tst may be calculated from equation (3) using temperature correction coefficients B and C.

The deterioration diagnosis device according to aspect 7 of the present invention includes a measurement unit that measures the battery temperature, terminal current, and terminal voltage during charging or discharging of the battery, an analysis unit that performs a transient response analysis of the battery based on the terminal current and the terminal voltage, and calculates the series resistance component of the battery at the battery temperature, a correction unit that corrects the series resistance component at the battery temperature to the series resistance component at a predetermined reference temperature, and a diagnosis unit that calculates a capacity decrease rate, which is the decrease rate of the storage capacity of the battery relative to the storage capacity in the initial state of the battery, based on the series resistance component at the reference temperature, and diagnoses the deterioration state of the battery, and is characterized in that the analysis unit reduces the battery to an equivalent circuit including a circuit in which the series resistance component and a parallel connection circuit in which a parallel capacitance component and a parallel resistance component are connected in parallel are connected in series, and performs the transient response analysis.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in different embodiments.

REFERENCE SIGNS LIST 1 Degradation diagnosis device 10 Measurement unit 11 Ammeter 12 Voltmeter 13 Thermometer 14, 15, 16 AD converter 20 Arithmetic processing unit 21 Analysis unit 22 Correction unit 23 Diagnosis unit 24 Control unit 30 Memory unit 90 Battery (storage battery)
C1 to CM, Cn Parallel capacitance component Co Series capacitance component Ri Series resistance component R1 to RM, Rn Parallel resistance component Eo Electromotive force (open circuit voltage)
Ib current (terminal current)
Vb Voltage (terminal voltage)
T temperature (storage battery temperature)
Tst Reference temperature Ri_st Series resistance component at reference temperature D Capacity decrease rate

Claims (7)

measuring the battery temperature, terminal current and terminal voltage while the battery is being charged or discharged;
performing a transient response analysis of the storage battery based on the terminal current and the terminal voltage, and calculating a series resistance component of the storage battery at the storage battery temperature;
correcting the series resistance component at the storage battery temperature to the series resistance component at a predetermined reference temperature;
and calculating a capacity decrease rate, which is a decrease rate of the storage capacity of the storage battery relative to the storage capacity in an initial state of the storage battery, based on the series resistance component at the reference temperature, to diagnose a deterioration state of the storage battery;
The transient response analysis is performed by reducing the storage battery to an equivalent circuit including a circuit connected in series to the series resistance component and a parallel connection circuit in which a parallel capacitance component and a parallel resistance component are connected in parallel ;
determining whether the battery temperature is within a predetermined range;
In the step of determining whether the battery temperature is within a predetermined range, if it is determined that the battery temperature is not within the predetermined range,
A deterioration diagnosis method, comprising the step of diagnosing the deterioration state of the storage battery being omitted . measuring the battery temperature, terminal current and terminal voltage while the battery is being charged or discharged;
performing a transient response analysis of the storage battery based on the terminal current and the terminal voltage, and calculating a series resistance component of the storage battery at the storage battery temperature;
correcting the series resistance component at the storage battery temperature to the series resistance component at a predetermined reference temperature;
and calculating a capacity decrease rate, which is a decrease rate of the storage capacity of the storage battery relative to the storage capacity in an initial state of the storage battery, based on the series resistance component at the reference temperature, to diagnose a deterioration state of the storage battery;
The transient response analysis is performed by reducing the storage battery to an equivalent circuit including a circuit connected in series to the series resistance component and a parallel connection circuit in which a parallel capacitance component and a parallel resistance component are connected in parallel;
In the step of correcting the series resistance component at the storage battery temperature to the series resistance component at a predetermined reference temperature,
A deterioration diagnosis method, characterized in that, when the battery temperature is expressed as T [K], the reference temperature is expressed as Tst [K], and the series resistance component at the battery temperature T is expressed as Ri, the series resistance component Ri_st at the reference temperature Tst is calculated from the following formula (E1) using temperature correction coefficients B and C.

In the step of diagnosing a deterioration state of the storage battery,
3. The degradation diagnosis method according to claim 1, wherein the capacity decrease rate is calculated from a linear equation for the series resistance component at the reference temperature. 4. The degradation diagnosis method according to claim 1, wherein the equivalent circuit further includes a series capacitance component connected in series with the series resistance component and the parallel connection circuit. 5. The degradation diagnosis method according to claim 1, wherein the equivalent circuit includes a circuit in which a plurality of parallel-connected circuits, in which a parallel capacitance component and a parallel resistance component are connected in parallel, are connected in series. A measurement unit for measuring a battery temperature, a terminal current, and a terminal voltage while the battery is being charged or discharged;
an analysis unit that performs a transient response analysis of the storage battery based on the terminal current and the terminal voltage, and calculates a series resistance component of the storage battery at the storage battery temperature;
a correction unit that corrects the series resistance component at the storage battery temperature to the series resistance component at a predetermined reference temperature;
a diagnosis unit that calculates a capacity decrease rate, which is a decrease rate of a storage capacity of the storage battery relative to a storage capacity in an initial state of the storage battery, based on the series resistance component at the reference temperature, and diagnoses a deterioration state of the storage battery;
The analysis unit reduces the storage battery to an equivalent circuit including a circuit in which the series resistance component and a parallel connection circuit in which a parallel capacitance component and a parallel resistance component are connected in parallel are connected in series, and performs the transient response analysis ;
a control unit that determines whether the battery temperature measured by the measurement unit is within a predetermined range;
a control unit that determines whether the temperature of the storage battery measured by the measurement unit is not within the predetermined range, and then the diagnosis unit does not diagnose the deterioration state of the storage battery . A measurement unit for measuring a battery temperature, a terminal current, and a terminal voltage while the battery is being charged or discharged;
an analysis unit that performs a transient response analysis of the storage battery based on the terminal current and the terminal voltage, and calculates a series resistance component of the storage battery at the storage battery temperature;
a correction unit that corrects the series resistance component at the storage battery temperature to the series resistance component at a predetermined reference temperature;
a diagnosis unit that calculates a capacity decrease rate, which is a decrease rate of a storage capacity of the storage battery relative to a storage capacity in an initial state of the storage battery, based on the series resistance component at the reference temperature, and diagnoses a deterioration state of the storage battery;
The analysis unit reduces the storage battery to an equivalent circuit including a circuit in which the series resistance component and a parallel connection circuit in which a parallel capacitance component and a parallel resistance component are connected in parallel are connected in series, and performs the transient response analysis;
a correction unit that calculates the series resistance component Ri_st at the reference temperature Tst from the following formula (E1) using temperature correction coefficients B and C, when the battery temperature is expressed as T [K], the reference temperature is Tst [K], and the series resistance component at the battery temperature T is expressed as Ri:

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