JP5554310B2 - Internal resistance measuring device and internal resistance measuring method - Google Patents

Description

  The present invention relates to an internal resistance measuring device and an internal resistance measuring method.

  In Patent Document 1, every time the continuous elapsed period reaches a predetermined time after the power is turned off, the amount of decrease in the terminal voltage of the battery is measured while passing a predetermined alternating current through the battery. A technique for obtaining an internal resistance of a battery from a current value of an alternating current is disclosed.

  Further, in Patent Document 2, when the secondary battery is in a predetermined discharge polarization state, the voltage and current of the secondary battery are measured and stored as data, and when the stored data exceeds a predetermined number A technique for calculating the internal resistance of a secondary battery using these data is disclosed.

JP 2004-168263 A JP 2004-31170 A

  By the way, the technique disclosed in Patent Document 1 has a problem that the internal resistance cannot be obtained until a predetermined time has elapsed since the power was turned off.

  Further, the technique disclosed in Patent Document 2 has a problem that the secondary battery is in a predetermined discharge polarization state, and further, the internal resistance cannot be obtained until a predetermined number of data is stored. .

  Accordingly, an object of the present invention is to provide an internal resistance measuring device and an internal resistance measuring method capable of obtaining the internal resistance of a secondary battery in a short time.

In order to solve the above-mentioned problems, the present invention provides an internal resistance measuring device for measuring the internal resistance of a secondary battery, and estimates a polarization voltage based on a temporal change in the voltage of the secondary battery after stopping charging and discharging. An estimation unit, an energizing unit for passing a charging current or a discharging current to the secondary battery, a detecting unit for detecting a voltage and a current when the energizing unit conducts the current to the secondary battery, and the detecting unit Based on the value of the voltage change due to the energization of the secondary battery obtained by excluding the influence of the polarization voltage estimated by the estimation means from the detected voltage, and the value of the current detected by the detection means Calculating means for calculating the internal resistance of the secondary battery.
According to such a configuration, the internal resistance of the secondary battery can be obtained in a short time.

According to another aspect of the invention, in addition to the above-described invention, the estimating means extends the measurement time when the temperature of the secondary battery is low, and shortens the measurement time when the temperature is high. To do.
According to such a configuration, the internal resistance can be accurately obtained regardless of the temperature.

According to another invention, in addition to the above invention, the calculation means obtains the value of the voltage change before and after energization detected by the detection means by subtracting the value of the polarization voltage estimated by the estimation means. The internal resistance of the secondary battery is calculated by dividing the calculated value by the value of the current detected by the detecting means.
According to such a configuration, the influence of polarization can be excluded by subtraction, and an accurate internal resistance can be obtained.

According to another aspect of the invention, in addition to the above-described invention, the calculation unit may be configured to change a voltage change value before and after energization detected by the voltage detection unit to a predetermined value corresponding to the polarization voltage estimated by the estimation unit. The internal resistance of the secondary battery is calculated by dividing the value obtained by multiplying the coefficient by the value of the current detected by the detecting means.
According to such a configuration, the influence of polarization can be excluded by multiplying by a coefficient, and an accurate internal resistance can be obtained.

Further, the present invention provides an internal resistance measuring method for measuring an internal resistance of a secondary battery, wherein an estimation step for estimating a polarization voltage based on a temporal change in the voltage of the secondary battery after stopping charging and discharging; An energizing step for passing a charging current or a discharging current to the secondary battery, a detecting step for detecting a voltage and current when the secondary battery is energized by the energizing step, and the voltage detected by the detecting step Based on the value of voltage change due to energization of the secondary battery obtained by excluding the influence of the polarization voltage estimated in the estimation step, and the value of the current detected in the detection step, the inside of the secondary battery And a calculating step for calculating the resistance.
According to such a method, the internal resistance of the secondary battery can be obtained in a short time.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the internal resistance measuring apparatus and internal resistance measuring method which can obtain | require the internal resistance of a secondary battery in a short time.

It is a figure for demonstrating the principle of the internal resistance measuring apparatus which concerns on embodiment of this invention. It is a figure which shows the voltage change of the secondary battery after a charge / discharge stop. It is a flowchart for demonstrating the operation | movement of the figure shown in FIG. It is a figure which shows the detailed structural example of the internal resistance measuring apparatus which concerns on embodiment of this invention. It is a figure which shows the detailed structural example of the control part shown in FIG. It is a flowchart for demonstrating operation | movement of embodiment shown in FIG. It is a flowchart for demonstrating the detail of the pulse discharge process shown in FIG. It is a figure which shows the temporal variation | change_quantity of the internal resistance by charge polarization. It is a figure which shows the time variation | change_quantity of the internal resistance by discharge polarization.

  Next, an embodiment of the present invention will be described.

(A) Description of Operation Principle of the Present Invention FIG. 1 is a diagram for explaining the operation principle of the internal resistance measurement device according to the embodiment of the present invention. As shown in this figure, the internal resistance measuring apparatus 1 according to the embodiment of the present invention includes an estimating unit 1a, a conducting unit 1b, a detecting unit 1c, and a calculating unit 1d. Measure resistance. Here, the estimation means 1a estimates the polarization voltage based on the temporal change of the voltage of the secondary battery B after the charge / discharge is stopped. The energization means 1b passes a charging current or a discharging current to the secondary battery B. The detecting means 1c detects the voltage and current when the secondary battery B is energized by the energizing means 1b. The calculation means 1d detects the value of the voltage change due to the energization of the secondary battery B obtained by excluding the influence of the polarization voltage estimated by the estimation means 1a from the voltage detected by the detection means 1c, and the detection means 1c. The internal resistance of the secondary battery B is calculated based on the value of the current thus obtained.

  Next, the operation of the internal resistance measuring apparatus 1 shown in FIG. 1 will be described. FIG. 2 is a diagram illustrating a change in voltage of the secondary battery B. When charging of the secondary battery B is stopped at time T0, the voltage of the secondary battery B gradually decreases with time as shown by the solid line in FIG. 2, and approaches the stable open circuit voltage Voc shown by the broken line. Go. This is because the voltage of the secondary battery B shifts to a value higher than the stable open circuit voltage Voc due to polarization (mainly charge polarization in the example of FIG. 2), and the polarization is eliminated over time. It is.

  As a method for measuring the internal resistance of the secondary battery B, for example, a pulse-shaped charging current or discharging current having a predetermined cycle is passed to the secondary battery B for a predetermined period, and the current I flowing at that time is energized. There is a method of obtaining the internal resistance R as R = ΔV / I based on the voltage change ΔV before and after the above. However, as shown in FIG. 2, when polarization is present, the voltage change ΔV includes a voltage change ΔVa due to polarization. Since the polarization is an apparent voltage, when the voltage change ΔVa due to this polarization is included, the calculated internal resistance includes an error. Therefore, in the present embodiment, when the polarization voltage is estimated from the transition of the voltage of the secondary battery B and the internal resistance is obtained, the voltage change ΔVa due to this polarization is excluded from the detected voltage change ΔV. The internal resistance is obtained based on the pure voltage change ΔVb.

  Next, the operation of the embodiment shown in FIG. 1 will be described in detail with reference to the flowchart shown in FIG.

  In step S10, it is determined whether charging / discharging of the secondary battery B is stopped. If it is determined that the charging is stopped (step S10: Yes), the process proceeds to step S11, and otherwise (step S10: No). Repeat the same process.

  In step S11, the estimation means 1a measures the voltage transition of the secondary battery B. Specifically, the temporal transition of the voltage shown in FIG. 2 is measured for a certain period (for example, 30 minutes).

  In step S12, the estimation means 1a estimates the polarization voltage Vp of the secondary battery B from the change in voltage measured in step S11. The polarization voltage Vp refers to a voltage indicated by ΔVa in FIG. 2 (difference between a voltage indicated by a solid line and a stable open circuit voltage). For example, the estimating means 1a estimates the polarization voltage Vp at a predetermined time t by obtaining a parameter of a predetermined function f (t) indicating a temporal change in voltage from a plurality of measurement results.

  In step S <b> 13, the energization unit 1 b applies an energization pulse (charge pulse or discharge pulse) to the secondary battery B.

  In step S14, the detection means 1c detects the voltage change ΔV of the secondary battery B before and after application of the energization pulse by the energization means 1b.

  In step S15, the detection unit 1c detects the current I flowing in the secondary battery B during the application of the pulse by the energization unit 1b.

  In step S16, the calculation means 1d calculates the equation R = (ΔV−Vp) based on the voltage change ΔV detected in step S14, the polarization voltage Vp estimated in step S12, and the current I detected in step S15. The internal resistance R is calculated from / I. Alternatively, the polarization voltage Vp and the correction coefficient γ may be associated and stored in a table or the like, and ΔVb may be obtained by multiplying the voltage change ΔV by the correction coefficient γ corresponding to the polarization voltage Vp. In the case of this method, the internal resistance R can be calculated by, for example, R = γ × ΔV / I.

  In step S17, the value of the internal resistance R calculated in step S16 is output.

  Generally, it takes a very long time (for example, several to several tens of hours) until the polarization of the secondary battery B is eliminated and becomes substantially the same as the stable open circuit voltage. For this reason, as in this embodiment, the internal resistance can be obtained in a short time without waiting for the very long time described above by estimating the polarization and eliminating the influence thereof to obtain the internal resistance. Further, by such a method, the internal resistance can be accurately obtained regardless of the state of polarization (for example, the magnitude of polarization).

(B) Description of Configuration of Embodiment FIG. 4 is a diagram illustrating a power supply system of a vehicle having an internal resistance measurement device according to an embodiment of the present invention. In this figure, the internal resistance measuring device 1 includes a control unit 10, a voltage sensor 11, a current sensor 12, a temperature sensor 13, and a discharge circuit 15 as main components, and measures the internal resistance of the secondary battery 14. .

  Here, the control unit 10 controls the discharge circuit 15 and refers to outputs from the voltage sensor 11, the current sensor 12, and the temperature sensor 13 to detect the state of the secondary battery 14. The voltage sensor 11 detects the terminal voltage of the secondary battery 14 and notifies the control unit 10 of it. The current sensor 12 detects the current flowing through the secondary battery 14 and notifies the control unit 10 of the current. The temperature sensor 13 detects the secondary battery 14 itself or the surrounding environmental temperature, and notifies the control unit 10 of it. The discharge circuit 15 is configured by, for example, a semiconductor switch and a resistance element connected in series, and the secondary battery 14 is intermittently discharged when the control unit 10 performs on / off control of the semiconductor switch.

  The secondary battery 14 is composed of, for example, a lead storage battery that uses lead dioxide as the positive electrode (anode plate), sponge-like lead as the negative electrode (cathode plate), and dilute sulfuric acid as the electrolyte, and is charged by the alternator 16 to start the motor. 18 is driven to start the engine 17 and supply power to the load 19. The alternator 16 is driven by the engine 17 to generate AC power, convert it into DC power by a rectifier circuit, and charge the secondary battery 14.

  The engine 17 is composed of, for example, a reciprocating engine such as a gasoline engine and a diesel engine, a rotary engine, or the like. The engine 17 is started by a starter motor 18 and drives driving wheels via a transmission to give propulsive force to the vehicle. Drive to generate power. The starter motor 18 is constituted by, for example, a DC motor, generates a rotational force by the electric power supplied from the secondary battery 14, and starts the engine 17. The load 19 includes, for example, an electric steering motor, a defogger, a light, an ignition coil, a car audio, a car navigation, and the like, and operates with electric power from the secondary battery 14 and the alternator 16.

FIG. 5 is a diagram illustrating a detailed configuration example of the control unit 10 illustrated in FIG. 4 . As shown in this figure, the control unit 10 includes a CPU (Central Processing Unit) 10a, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, an I / F (Interface) 10d, a bus 10e, and a communication. Part 10f. Here, the CPU 10a controls each unit based on the program 10ba stored in the ROM 10b. The ROM 10b is configured by a semiconductor memory or the like, and stores a program 10ba or the like. The RAM 10c is configured by a semiconductor memory or the like, and stores a parameter 10ca generated when the program 10ba is executed. The I / F 10d converts the signals supplied from the voltage sensor 11, the current sensor 12, and the temperature sensor 13 into digital signals and takes them in, and supplies a drive signal to the discharge circuit 15 to control it. The bus 10e is a signal line group for electrically connecting the CPU 10a, the ROM 10b, the RAM 10c, and the I / F 10d to each other and enabling information exchange between them. The communication unit 10f is connected to another device (for example, an ECU (Engine Control Unit) (not shown)) via a communication line, and exchanges information with another device.

(C) Description of Operation of Embodiment Next, the operation of this embodiment will be described. FIG. 6 is a flowchart for explaining the flow of processing executed in the control unit 10 shown in FIG. When the processing of this flowchart is executed, the following steps are executed.

  In step S30, the CPU 10a determines whether or not the engine 17 has been stopped. If it is determined that the engine 17 has stopped (step S30: Yes), the process proceeds to step S31, and otherwise (step S30: No). Similar processing is repeated. Specifically, the CPU 10a refers to the output of the current sensor 12, and if the current flowing through the secondary battery 14 is less than a predetermined threshold, the CPU 17a determines that the engine 17 has stopped and proceeds to step S31. Note that the stop of the engine 17 is determined because the stop of the engine 17 means the stop of charge / discharge.

  In step S31, the CPU 10a refers to the output of the temperature sensor 13 and detects the temperature of the secondary battery 14.

In step S32, the CPU 10a proceeds to step S33 if the temperature of the secondary battery 14 detected in step S31 is high, proceeds to step S34 if it is normal temperature, and proceeds to step S35 if it is low. move on. Specifically, if the temperature of the secondary battery 14 is 45 ° C. or higher, the process proceeds to Step S33 as being high temperature, and if it is 10 ° C. or more and less than 45 ° C., the process proceeds to Step S34 as normal temperature and less than 10 ° C. If it is, the process proceeds to step S35 because the temperature is low. Note that the above-described temperature criterion is merely an example, and other temperatures may be used as the criterion.

  In step S33, the CPU 10a refers to the output of the voltage sensor 11 and measures the transition of the voltage of the secondary battery 14 for 30 minutes.

  In step S34, the CPU 10a refers to the output of the voltage sensor 11 and measures the transition of the voltage of the secondary battery 14 for 60 minutes.

  In step S35, the CPU 10a refers to the output of the voltage sensor 11 and measures the transition of the voltage of the secondary battery 14 for 90 minutes.

The reason for changing the voltage change measurement time according to the temperature of the secondary battery 14 is to perform the optimum measurement according to the temperature because the state of occurrence of polarization varies depending on the temperature of the secondary battery 14. FIG. 8 is a diagram in which the difference (change amount) between the internal resistance value measured after 20 hours and the internal resistance value at each time when charge polarization occurs is plotted for each temperature. Such a difference occurs because there is an error due to the polarization voltage. From the comparison of the graphs of each temperature in FIG. 8, when the temperature is high, the change in the polarization voltage is large. In other words, when the temperature is high, the amount of change per time of polarization is larger than when the temperature is low, so that the polarization voltage can be estimated with relatively high accuracy even in a short-time measurement . On the other hand, FIG. 9 is a diagram similar to the case of discharge polarization. As shown in FIG. 9, in the case of discharge polarization, the amount of change in internal resistance due to temperature is small, and after about 30 minutes, the amount of change falls within the range of ± 0.1 mΩ regardless of temperature. The effect of temperature can be ignored for polarization .

In step S36, the CPU 10a estimates the open circuit voltage of the secondary battery 14 based on the voltage transition measured in steps S33 to S35. Specifically, the open circuit voltage is estimated by fitting parameters of a predetermined function including an exponential function, for example, based on the transition of the voltage measured in steps S33 to S35. Specifically, the stable open circuit voltage is Voc, the parameters are α and β, the elapsed time from the stop of the engine 17 is t, the voltage of the secondary battery 14 is V, and the exponential function is exp (). The mathematical formula shown is V = Voc + α × exp (−β × t). The stable open circuit voltage Voc can be estimated by obtaining the values of Voc and parameters α and β by fitting based on the change in the voltage V over time t. Note that the above is an example, and the stable open circuit voltage Voc may be obtained by other methods.

  In step S <b> 37, the CPU 10 a refers to the output of the voltage sensor 11 and detects the voltage V of the secondary battery 14.

  In step S38, the CPU 10a obtains the polarization voltage Vp (= V−Voc) by subtracting the stable open circuit voltage Voc obtained in step S36 from the voltage V of the secondary battery 14 detected in step S37.

  In step S39, the CPU 10a performs a pulse discharge process in which the secondary battery 14 is pulse-discharged and the voltage and current at that time are measured. FIG. 7 is a flowchart for explaining the details of the pulse discharge process. As shown in FIG. 7, in the pulse discharge process, in step S50, the CPU 10a controls the discharge circuit 15 to pulse discharge the secondary battery 14. Specifically, for example, pulse discharge is performed at a frequency of about 100 Hz for a period of about 1/10 second. In step S51, the CPU 10a refers to the output of the current sensor 12, and detects the current I flowing through the secondary battery 14 during pulse discharge. In step S52, the CPU 10a refers to the output of the voltage sensor 11 and detects the voltage change ΔV of the secondary battery 14 before and after the pulse discharge. Then, the processing returns (returns) to the processing of FIG.

  In step S40, the CPU 10a calculates the internal resistance R based on the result of the pulse discharge process in step S39. Specifically, the internal resistance R is obtained by substituting the current I detected in step S39 and the voltage change ΔV into the equation R = ΔV / I.

  In step S41, the CPU 10a outputs the value of the internal resistance R. Specifically, the CPU 10a outputs the value of the internal resistance R calculated in step S40 to, for example, an ECU (not shown) via the communication unit 10f.

  According to the above embodiment, the polarization voltage is estimated based on the temporal change of the voltage of the secondary battery 14, and the internal resistance is obtained based on the value obtained by excluding the polarization voltage from the voltage change after the pulse discharge. Since the internal resistance can be obtained even before the polarization voltage is stabilized, the internal resistance can be measured quickly.

  In addition, since the internal resistance can be measured without being affected by the polarization voltage, the internal resistance can be accurately obtained.

  Moreover, since the time for observing the voltage transition is adjusted according to the temperature, the internal resistance can be accurately obtained regardless of the temperature of the secondary battery 14.

(D) Description of Modified Embodiment The above embodiment is an example, and it is needless to say that the present invention is not limited to the case described above. For example, in the above embodiment, the discharge pulse is applied to the secondary battery 14, but the measurement may be performed by applying the charge pulse instead of the discharge pulse. Further, charging or discharging is not limited to a pulse waveform, and charging or discharging may be performed using a waveform other than a pulse (for example, a sine wave).

  In the above embodiment, as shown in FIG. 2, the internal resistance is calculated based on the value (= ΔVb) obtained by subtracting the polarization voltage ΔVa from the voltage change ΔV. ΔVb may be obtained by multiplying the voltage change ΔV by a predetermined correction coefficient γ corresponding to the voltage ΔVa. Specifically, a predetermined correction coefficient γ corresponding to ΔVa is stored in, for example, a table, or a function indicating these relationships is prepared, and the correction coefficient γ is acquired based on these tables or functions. Alternatively, ΔVb may be obtained by the equation ΔVb = γ × ΔV. The internal resistance R can be obtained by R = γ × ΔV / I.

In the above embodiment, in the process of step S36 shown in FIG. 6, the fitting is performed using a function including an exponential function to estimate the stable open circuit voltage Voc . However, the fitting is performed using a function other than this. It may be.

  In the above embodiment, the measurement time is changed into three temperature ranges of low temperature, normal temperature, and high temperature. For example, the measurement time is divided into two temperature ranges or four or more temperature ranges. You may make it divide.

  In the above embodiment, the processing is started when the engine 17 is stopped. However, when the secondary battery 14 is mounted other than the vehicle, the current flowing through the secondary battery 14 is more than the threshold value. The process may be started when the value becomes smaller.

In the above embodiment, depending on the internal resistance R, the value obtained by calculation is output as it is. However, for example, correction is performed based on the temperature of the secondary battery 14 and the value of the internal resistance after correction is performed. May be output .

DESCRIPTION OF SYMBOLS 1 Internal resistance measuring apparatus 10 Control part 10a CPU (estimation means, detection means, calculation means)
10b ROM
10c RAM
10d I / F
10e bus 10f communication unit 11 voltage sensor 12 current sensor 13 temperature sensor 14 secondary battery 15 discharge circuit (energization means)
16 Alternator 17 Engine 18 Starter motor 19 Load

Claims (5)

In the internal resistance measuring device that measures the internal resistance of the secondary battery,
An estimation means for estimating a polarization voltage based on a temporal change in the voltage of the secondary battery after stopping charging and discharging;
Energizing means for passing charging current or discharging current through the secondary battery;
Detecting means for detecting a voltage and a current when the current is passed to the secondary battery by the energizing means;
The value of the voltage change due to the energization of the secondary battery obtained by excluding the influence of the polarization voltage estimated by the estimation means from the voltage detected by the detection means, and the value of the current detected by the detection means Calculating means for calculating the internal resistance of the secondary battery based on
An internal resistance measuring device comprising:   2. The internal resistance measurement device according to claim 1, wherein the estimation unit lengthens the measurement time when the temperature of the secondary battery is low, and shortens the measurement time when the temperature is high.   The calculation means obtains a value obtained by subtracting the value of the polarization voltage estimated by the estimation means from the value of the voltage change before and after the energization detected by the detection means, and the value of the current detected by the detection means. The internal resistance measuring device according to claim 1, wherein the internal resistance of the secondary battery is calculated by dividing by a value.   The calculation means obtains a value obtained by multiplying a value of a voltage change before and after energization detected by the voltage detection means by a predetermined coefficient corresponding to the polarization voltage estimated by the estimation means. The internal resistance measurement device according to claim 1, wherein the internal resistance of the secondary battery is calculated by dividing by the value of the current detected by the method. In the internal resistance measurement method for measuring the internal resistance of the secondary battery,
An estimation step for estimating a polarization voltage based on a temporal change in the voltage of the secondary battery after stopping charging and discharging;
An energization step of passing a charging current or a discharging current through the secondary battery;
A detection step of detecting a voltage and a current when the secondary battery is energized by the energization step;
The value of the voltage change due to energization of the secondary battery obtained by excluding the influence of the polarization voltage estimated by the estimation step from the voltage detected by the detection step, and the value of the current detected by the detection step A calculation step of calculating the internal resistance of the secondary battery based on
A method for measuring internal resistance, comprising:

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