JP2015094710A - Device and method for estimating soundness of battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for estimating soundness of a battery which estimates soundness of a battery without discharging the battery.SOLUTION: A soundness estimation device 11 of a battery includes: a storage part 14 for storing in advance first information showing a relationship between a terminal voltage variation from a time point immediately after the end of charging the battery until a predetermined time elapses and soundness; a terminal voltage measurement part 12 for measuring a terminal voltage of the battery 10; a voltage variation amount calculation part 13 for calculating a terminal voltage variation amount from the time point immediately after the charging of the battery 10 until the predetermined time elapses; and a soundness calculation part 15 for calculating soundness according to the terminal voltage variation amount based on the first information.

Description

  The present invention relates to a soundness estimation device and a soundness estimation method for estimating the soundness of a battery.

  Conventionally, an apparatus for estimating the degree of deterioration (soundness) of a battery is known. For example, in Patent Document 1, a secondary battery is pulse-discharged with a constant current to calculate an internal resistance value of the secondary battery, and the obtained internal resistance value is compared with a preset data table to obtain a secondary battery. An apparatus for diagnosing the degree of degradation of the is described.

JP 2000-121710 A

  However, since the secondary battery needs to be pulse-discharged, the power of the secondary battery is consumed. For example, in an electric vehicle or the like equipped with a secondary battery, it is not desirable that power be consumed to diagnose the degree of deterioration of the secondary battery.

  The objective of this invention made | formed in view of this situation is providing the soundness estimation apparatus and soundness estimation method which estimate the soundness of a battery, without discharging a battery.

In order to solve the above-described problem, the battery health estimation device according to the first aspect of the present invention provides:
A storage unit that stores in advance first information indicating a relationship between a terminal voltage change amount until a predetermined time elapses from a time immediately after the end of charging of the battery and a soundness level;
A terminal voltage measurement unit for measuring the terminal voltage of the battery;
A voltage change amount calculation unit for calculating a terminal voltage change amount from the time immediately after the end of charging of the battery until the predetermined time elapses;
A soundness degree calculation unit that calculates a soundness degree corresponding to the terminal voltage change amount based on the first information.

Moreover, in the battery soundness estimation apparatus according to the second invention,
The end of charging is an end due to full charge in constant current and constant voltage charging.

Moreover, in the battery soundness estimation apparatus according to the third invention,
The storage unit stores in advance second information indicating a relationship between a temperature correction coefficient for correcting the terminal voltage change amount of the battery and the temperature of the battery,
The soundness estimation device
A temperature measuring unit for measuring the temperature of the battery;
A temperature correction coefficient calculator that calculates a temperature correction coefficient according to the temperature based on the second information;
A temperature correction unit that corrects the terminal voltage change amount using the temperature correction coefficient, and
The soundness calculation unit calculates soundness according to the corrected terminal voltage change amount.

Moreover, the battery health estimation method according to the fourth invention is:
Storing in advance in a storage unit information indicating a relationship between a terminal voltage change amount until a predetermined time elapses immediately after the end of charging of the battery and a soundness level;
Measuring the terminal voltage of the battery;
Calculating a terminal voltage change amount from the time immediately after the end of charging of the battery until the predetermined time elapses;
And calculating a soundness level corresponding to the terminal voltage change amount based on the information.

  According to the battery health estimation apparatus according to the first invention, the battery after charging is discharged in order to calculate the battery health SOH corresponding to the terminal voltage change amount Δv based on the information stored in the storage unit. The soundness SOH of the battery can be estimated without any problem.

  Further, according to the battery health estimation apparatus according to the second invention, since the state of the battery is stable at the time of full charge, the reproducibility of the terminal voltage fluctuation after the end of charging is improved, and the health level is improved. The estimation accuracy of can be improved.

  In addition, according to the battery health level estimation apparatus according to the third aspect of the invention, the temperature dependence of the terminal voltage change amount Δv that fluctuates according to the battery temperature T is corrected, so that the accuracy of estimation of the battery health level is improved. Is possible.

  Further, according to the battery health level estimation method according to the fourth aspect of the invention, the battery health level SOH is determined based on the terminal voltage change amount Δv, so that the battery health level SOH is not discharged without discharging the charged battery. Can be estimated.

It is a figure which shows the functional block of the soundness estimation apparatus of the battery which concerns on Embodiment 1 of this invention connected to the battery. It is a figure which shows the relationship between the terminal voltage and time of a battery from which a soundness differs. It is a figure which shows the relationship between a terminal voltage change amount and soundness. It is a flowchart which shows operation | movement of the soundness estimation apparatus of FIG. It is a figure which shows the functional block of the soundness estimation apparatus of the battery which concerns on Embodiment 2 of this invention connected to the battery. It is a figure which shows the relationship between the temperature of a battery, and a temperature correction coefficient. It is a flowchart which shows operation | movement of the soundness estimation apparatus of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
First, the soundness estimation apparatus according to Embodiment 1 of the present invention will be described. FIG. 1 is a functional block diagram of the soundness estimation apparatus according to Embodiment 1.

  As shown in FIG. 1, the soundness level estimation device 11 connected to the battery 10 includes a terminal voltage measurement unit 12, a voltage change amount calculation unit 13, a storage unit 14, and a soundness level calculation unit 15.

  The battery 10 is a rechargeable secondary battery, and is charged by, for example, constant current constant voltage charging (CCCV charging). In constant current / constant voltage charging, charging is performed by gradually increasing the charging voltage so as to maintain the charging current at a constant value after the start of charging. When charging proceeds and the charging voltage reaches a predetermined voltage value (for example, 4.2 V), charging is performed by gradually decreasing the charging current so as to maintain the charging voltage at the predetermined value. Then, when the charging current becomes equal to or less than a predetermined current value, it is determined that the battery is fully charged, and the charging is terminated. Although the battery 10 is described as being a lithium ion battery in the present embodiment, other types of batteries may be used.

  The terminal voltage measuring unit 12 is a voltage sensor, for example, and measures the terminal voltage of the battery 10.

The voltage change amount calculation unit 13 detects the end of charging of the battery 10. In addition, the voltage change amount calculation unit 13 calculates the change amount of the terminal voltage from the time immediately after the end of charging of the battery 10 until a predetermined time elapses. For example, when the charging of the battery 10 ends, the voltage change amount calculation unit 13 acquires the terminal voltage v _t0 at time t ₀ immediately after the end of charging from the voltage measurement unit. The voltage change amount calculation unit 13 acquires, from the voltage measurement unit, the terminal voltage v _t1 at time t ₁ when a predetermined time (for example, 5 seconds) has elapsed from time t ₀ . Then, the voltage change amount calculation unit 13 calculates the terminal voltage change amount Δv = v _t0 −v _t1 from time t ₀ to time t ₁ .

Here, the terminal voltage of the battery after completion of charging will be described with reference to FIG. 2, the time t ₀ stipulates that the reference time (0 seconds), indicating the change in the terminal voltage of the battery over time from the reference time. Moreover, FIG. 2 shows the terminal voltage of the same battery in three different soundness levels SOH. The soundness level SOH (State of Health) is defined by a ratio between a design capacity DC (Design Capacity) and a full charge capacity FCC (Full Charge Capacity), and is a value indicating the degree of deterioration of the battery. The soundness level SOH indicates that the battery has not deteriorated when the value is 100%, and the lower the value of the soundness level SOH, the more the battery is more deteriorated.

  As shown in FIG. 2, the terminal voltage of the battery decreases due to abrupt fluctuations in a relatively short time, for example, about 1 or 2 seconds after the end of charging (see symbol A in FIG. 2), and then gradually decreases due to gentle fluctuations. (Refer to symbol B in FIG. 2) and fluctuate so as to approach a constant voltage value.

The degree of decrease in the terminal voltage due to sudden fluctuations differs depending on the battery health level SOH. The higher the soundness level SOH, that is, the lower the battery deterioration, the more the terminal voltage decreases. On the other hand, the decrease in the terminal voltage due to the gradual fluctuation is almost the same regardless of the value of the soundness level SOH. Therefore, the terminal voltage _{v t0} at time _{t 0,} the difference between the terminal voltage _{v t1} at time _{t 1} when the terminal voltage is varying slowly, i.e. the time _{t 0} from a predetermined time (e.g., 5 seconds) elapsed time t The terminal voltage change amount Δv up to ₁ depends on the battery health SOH (see FIG. 3). The correspondence between the terminal voltage change amount Δv and the soundness level SOH can be calculated by experiment or simulation.

  The storage unit 14 (see FIG. 1) stores a soundness data table 16 in advance.

Soundness data table 16 is calculated by an experiment or simulation, from time t ₀ immediately after completion of charging of the battery a predetermined time (e.g., 5 seconds) and the terminal voltage change amount Δv until time t ₁ has elapsed, the soundness SOH Is a lookup table including information (first information) indicating the relationship between In the soundness level data table 16, the value of the soundness level SOH is uniquely determined with respect to the value of the terminal voltage change amount Δv.

  The soundness level calculation unit 15 (see FIG. 1) calculates the soundness level SOH of the battery 10 according to the terminal voltage change amount Δv based on the first information stored in the storage unit 14. Specifically, the soundness level calculation unit 15 extracts the soundness level SOH corresponding to the terminal voltage change amount Δv calculated by the voltage change amount calculation unit 13 from the soundness level data table 16 stored in the storage unit 14. The soundness level calculation unit 15 outputs the extracted soundness level SOH as the estimated soundness level SOH of the battery 10.

  Next, with reference to FIG. 4, the process which the soundness estimation apparatus 11 of this Embodiment performs is demonstrated. The process starts when the voltage change amount calculation unit 13 detects the end of charging of the battery 10.

First, the voltage change amount calculation unit 13 acquires the terminal voltage v _t0 from the terminal voltage measurement unit 12 at the time immediately after the end of charging of the battery 10 (time t0) (step S100).

Then, the voltage change amount calculation unit 13, from the time _{t 0} a predetermined time (e.g., 5 seconds) to wait until the elapsed (step S101).

Subsequently, the voltage change amount calculation unit 13 obtains the terminal voltage v _t1 from the terminal voltage measurement unit 12 when a predetermined time has elapsed from the time t ₀ (time t ₁ ) (step S102).

Subsequently, the voltage change amount calculation unit 13 calculates the terminal voltage change amount Δv by subtracting the terminal voltage v _t1 of step S102 from the terminal voltage v _{t0 of} step S100 (step S103).

  Then, the soundness level calculation unit 15 extracts the soundness level SOH corresponding to the terminal voltage change amount Δv in step S103 from the soundness level data table 16 stored in the storage unit 14 (step S104).

  As described above, according to the battery health level estimation device 11 according to the present embodiment, the battery health level SOH corresponding to the terminal voltage change amount Δv is calculated based on the information stored in the storage unit 14. The battery health SOH can be estimated without discharging the subsequent battery. In addition, the battery is generally charged frequently, and the soundness level SOH can be estimated for each charge without requiring a special operation. In addition, since no special additional device is required, the soundness level SOH can be estimated with a simple configuration. In addition, in the case of a battery in which a plurality of cells are connected in series, the processing load can be reduced as compared with the conventional general technique in which the internal resistance of each cell needs to be estimated in order to estimate the soundness SOH.

Further, the battery health estimation device 11 sets the time t ₀ immediately after the end of charging due to full charge in constant current constant voltage charging, and starts soundness estimation processing. When charging progresses in constant-current / constant-voltage charging, the charging is switched to gentle charging by constant-voltage charging, so that the state of the battery is stable when fully charged. For this reason, it is possible to improve the reproducibility of the terminal voltage fluctuation after the end of charging and to improve the estimation accuracy of the soundness level.

(Embodiment 2)
Next, a soundness estimation apparatus according to Embodiment 2 of the present invention will be described. FIG. 5 is a functional block diagram of the soundness estimation apparatus according to Embodiment 2. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The soundness level estimation apparatus 110 according to the second embodiment includes a terminal voltage measurement unit 12, a voltage change amount calculation unit 13, a storage unit 140, a soundness level calculation unit 15, a temperature measurement unit 170, and a temperature correction coefficient calculation. Unit 180 and a temperature correction unit 190. The terminal voltage measurement unit 12, the voltage variation calculation unit 13, and the soundness calculation unit 15 are the same as those in the first embodiment.

  The storage unit 140 stores a soundness level data table 16 and a temperature correction coefficient data table 200 in advance. The soundness level data table 16 is the same as that of the first embodiment.

  The temperature correction coefficient data table 200 is a lookup table including information (second information) indicating a relationship between the temperature correction coefficient c for correcting the terminal voltage change amount Δv of the battery and the battery temperature T. The temperature correction coefficient c is a parameter for correcting the temperature dependence of the terminal voltage change amount Δv.

In general, the battery temperature T and the terminal voltage change amount Δv from the time immediately after the end of charging until a predetermined time elapses have a correlation, and when the battery temperature T decreases, the terminal voltage change amount Δv is To increase. In the present embodiment, the temperature correction coefficient c is the ratio of the terminal voltage change amount Δv at the battery temperature T at the time of measurement to the terminal voltage change amount Δv ₀ at the reference temperature. The reference temperature is the temperature of the battery when the soundness data table 16 is generated. As for the relationship between the temperature correction coefficient c and the battery temperature T, the value of the temperature correction coefficient c at a reference temperature (for example, 25 ° C.) is set to 1 as shown in FIG. As the temperature T becomes a value lower than the reference temperature, the value of the temperature correction coefficient c increases, and particularly increases greatly from −10 ° C. to −20 ° C. On the other hand, the value of the temperature correction coefficient c decreases as the temperature T becomes higher than the reference temperature.

  The temperature measurement unit 170 (see FIG. 5) is, for example, a temperature sensor, and measures the temperature of the battery 10.

The temperature correction coefficient calculation unit 180 calculates a temperature correction coefficient c corresponding to the battery temperature T based on the second information stored in the storage unit 140. Specifically, the temperature correction coefficient calculation unit 180 acquires the temperature T of the battery 10 from the temperature measurement unit 170 at a time t ₁ when a predetermined time (for example, 5 seconds) has elapsed from the time t ₀ immediately after the end of charging of the battery 10. Thus, the temperature correction coefficient c corresponding to the temperature T is extracted from the temperature correction coefficient data table 200 stored in the storage unit 140.

The temperature correction unit 190 corrects the terminal voltage change amount Δv calculated by the voltage change amount calculation unit 13 using the temperature correction coefficient calculated by the temperature correction coefficient calculation unit 180. For example, the temperature correction unit 190 divides the terminal voltage change Δv by the temperature correction coefficient c to calculate a corrected terminal voltage change Δv ₀ . In other words, the temperature correction unit 190 converts the terminal voltage change Δv at the battery temperature T at the time of measurement into the terminal voltage change Δv ₀ at the reference temperature using the temperature correction coefficient c.

  Next, with reference to FIG. 7, the process which the soundness estimation apparatus 110 of this Embodiment performs is demonstrated. The process starts when the voltage change amount calculation unit 13 detects the end of charging of the battery 10.

  First, in steps S200 to S203, processing similar to that in steps S100 to S103 of the first embodiment is performed.

Next, the temperature correction coefficient calculation unit 180 acquires the temperature T of the battery from the temperature measurement unit 170 when a predetermined time has elapsed (time t ₁ ) immediately after the end of charging of the battery 10 (time t ₀ ). (Step S204).

  Subsequently, the temperature correction coefficient calculation unit 180 extracts the temperature correction coefficient c corresponding to the temperature T acquired in step S204 from the temperature correction coefficient data table 200 stored in the storage unit 140 (step S205).

Next, the temperature correction unit 190 corrects the terminal voltage change amount Δv calculated in step S203 using the temperature correction coefficient c extracted in step S205 (step S206). For example, the temperature correction unit 190 divides the terminal voltage change Δv by the temperature correction coefficient c to calculate a corrected terminal voltage change Δv ₀ .

The health calculation unit 15, the soundness SOH corresponding to the terminal voltage variation Delta] v ₀ corrected in step S206, the storage unit 140 is extracted from the health of the data table 16 to be stored (step S207).

  Thus, according to battery health estimation apparatus 110 according to the present embodiment, in order to correct the temperature dependence of terminal voltage variation Δv that varies according to battery temperature T, battery health SOH The estimation accuracy can be improved.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, functions and the like included in each means and each step can be rearranged so as not to be logically contradictory, and a plurality of means and steps can be combined into one or divided. .

Further, in the above-described embodiment, the voltage change amount calculation unit 13 has described the configuration for acquiring the terminal voltage v _t1 from the terminal voltage measurement unit 12 when a predetermined time has elapsed from the time t ₀ (time t ₁ ). However, a configuration for calculating the terminal voltage v _t1 is also possible. For example, the voltage change amount calculation unit 13 acquires the terminal voltage of the battery 10 at each time point of 1 second before and after the time t ₁ from the terminal voltage measurement unit 12, calculates an average value thereof, and calculates the terminal voltage v _t1 . It may be determined.

  In the above-described embodiment, the configuration has been described in which the storage units 14 and 140 store a lookup table including information (first information) indicating the relationship between the terminal voltage change amount Δv and the soundness level SOH. For example, the structure which memorize | stored the numerical formula which approximated the relationship of terminal voltage variation | change_quantity (DELTA) v and soundness SOH shown in FIG. 3 as 1st information may be sufficient. In this case, the soundness level calculation unit 15 calculates the soundness level SOH by substituting the terminal voltage change amount Δv or Δv0 acquired from the voltage change amount calculation unit 13 or the temperature correction unit 190 into the approximate expression. Similarly, in the second embodiment, the configuration has been described in which the storage unit 140 stores a lookup table including information (second information) indicating the relationship between the temperature correction coefficient c and the battery temperature T. A configuration in which a mathematical expression approximating the relationship between the temperature correction coefficient c and the temperature T illustrated in FIG. 6 may be stored as the second information. In this case, the temperature correction coefficient calculation unit 180 calculates the temperature correction coefficient c by substituting the temperature T of the battery 10 acquired from the temperature measurement unit 170 into the approximate expression.

Further, in the above-described embodiment, the time when the battery is fully charged in the constant current and constant voltage charging is determined to be the charging end, but another time may be determined to be the charging end. For example, to terminate charging when the Tsu switched from the constant current charging to constant voltage charging may be configured to time t ₀ the time. Moreover, you may employ | adopt other charge methods other than constant current constant voltage charge.

Further, in the above embodiment, although defined as time t ₁ to the time that has elapsed from time t ₀ 5 seconds immediately after charging, it may be defined as time t ₁ to the time when the arbitrary time has elapsed. For example, since the terminal voltage v fluctuates abruptly in 1 and 2 seconds immediately after charging (see symbol A in FIG. 2), more than 2 seconds have elapsed after charging when the terminal voltage v is stable due to the progress of battery polarization relaxation. point in time may be defined as time t ₁ a. Alternatively, a time point within 1 or 2 seconds immediately after charging may be determined as time t ₁ in accordance with battery characteristics or usage conditions.

  In the above-described second embodiment, the configuration in which the storage unit 140 stores the soundness level data table 16 and the temperature correction coefficient data table 200 has been described. For example, the two storage units include the soundness level data table 16 and the temperature correction coefficient. The data table 200 may be stored respectively.

DESCRIPTION OF SYMBOLS 10 Battery 11,110 Soundness estimation apparatus 12 Terminal voltage measurement part 13 Voltage change amount calculation part 14,140 Storage part 15 Soundness calculation part 16 Soundness data table 170 Temperature measurement part 180 Temperature correction coefficient calculation part 190 Temperature correction part 200 Temperature correction coefficient data table

Claims (4)

A storage unit that stores in advance first information indicating a relationship between a terminal voltage change amount until a predetermined time elapses from a time immediately after the end of charging of the battery and a soundness level;
A terminal voltage measurement unit for measuring the terminal voltage of the battery;
A voltage change amount calculation unit for calculating a terminal voltage change amount from the time immediately after the end of charging of the battery until the predetermined time elapses;
A soundness calculation unit for calculating soundness according to the terminal voltage change amount based on the first information;
A device for estimating the degree of soundness of a battery.   It is a soundness estimation apparatus of Claim 1, Comprising: The said charge completion is a soundness estimation apparatus which is completion | finish by the full charge in constant current constant voltage charge. The soundness estimation device according to claim 1 or 2,
The storage unit stores in advance second information indicating a relationship between a temperature correction coefficient for correcting the terminal voltage change amount of the battery and the temperature of the battery,
The soundness estimation device
A temperature measuring unit for measuring the temperature of the battery;
A temperature correction coefficient calculator that calculates a temperature correction coefficient according to the temperature based on the second information;
A temperature correction unit that corrects the terminal voltage change amount using the temperature correction coefficient, and
The soundness level calculation unit is configured to calculate a soundness level corresponding to the corrected terminal voltage change amount. Storing in advance in a storage unit information indicating a relationship between a terminal voltage change amount until a predetermined time elapses immediately after the end of charging of the battery and a soundness level;
Measuring the terminal voltage of the battery;
Calculating a terminal voltage change amount from the time immediately after the end of charging of the battery until the predetermined time elapses;
Calculating a soundness level according to the terminal voltage change amount based on the information;
Battery health estimation method including

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