JP2020136069A - Rechargeable battery state detector and rechargeable battery state detection method - Google Patents

Abstract

To detect occurrence of polarity inversion accurately.SOLUTION: A rechargeable battery state detector for detecting the state of rechargeable battery includes input means (I/F10e) for inputting signals from a voltage detection part 11 for detecting the terminal voltage of the rechargeable battery and from a current detection part 12 for detecting a current flowing to the rechargeable battery, first determination means (CPU10a) for determining that the terminal voltage of the rechargeable battery is abnormal when it is less than a prescribed threshold level while the rechargeable battery is discharging, on the basis of a signal input from the input means, and second determination means (CPU10a) for determining whether polarity inversion has occurred on the basis of at least one of a change in the terminal voltage of the rechargeable battery and a change in the internal resistance, after stoppage of discharge, when the first determination means determined abnormal.SELECTED DRAWING: Figure 1

Description

The present invention relates to a rechargeable battery state detecting device and a rechargeable battery state detecting method.

Failure or abnormality of a rechargeable battery is a major problem for a device that supplies power from a rechargeable battery or a four-wheeled vehicle or a two-wheeled vehicle that relies on a rechargeable battery for starting an engine.

In autonomous vehicles, which are expected to be realized in the near future, sudden power loss due to a failure or abnormality of a rechargeable battery becomes a problem related to reliability.

There are multiple causes of failure or abnormality of a rechargeable battery, but if an over-discharge results in a "polarization" in which the positive electrode reaction and the charging reaction are reversed, the rechargeable battery will suffer irreparable damage. It is known to give, fail or lead to anomalies.

As a method of detecting an abnormality of a rechargeable battery typified by such inversion, for example, as in Patent Document 1, a method of estimating based on the behavior of the voltage of the rechargeable battery has been proposed. ..

Japanese Unexamined Patent Publication No. 06-89743

By the way, it is extremely difficult to accurately discriminate from an over-discharge in a range that does not reach the turning pole by the method disclosed in Patent Document 1 that detects the turning pole using only the behavior of the voltage as an index. In this case, there is a problem that excessive damage is estimated for a rechargeable battery that has received only a recoverable level of damage.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rechargeable battery state detecting device and a rechargeable battery state detecting method capable of accurately detecting the occurrence of inversion. It is supposed to be.

In order to solve the above problems, the present invention determines in a rechargeable battery state detection device that detects the state of a rechargeable battery, a voltage detection unit that detects a terminal voltage of the rechargeable battery and a current flowing through the rechargeable battery. Based on the input means for inputting the signal from the current detection unit to be detected and the signal input from the input means, when the rechargeable battery is discharging, the terminal voltage of the rechargeable battery has a predetermined threshold value. If it is less than, the first determination means that determines that it is abnormal, and if it is determined that it is abnormal by the first determination means, after the discharge is stopped, the change in the terminal voltage and the change in the internal resistance of the rechargeable battery It is characterized by having a second determination means for determining the presence or absence of occurrence of turning pole based on at least one of them.
According to such a configuration, it is possible to accurately detect the occurrence of turning poles.

Further, the present invention is characterized in that the second determination means determines that a repolarization has occurred when the internal resistance decreases after the discharge of the rechargeable battery is stopped.
According to such a configuration, it is possible to accurately detect the occurrence of turning poles.

Further, in the present invention, the second determination means determines that a repolarization has occurred when the terminal voltage gradually increases as compared with the case of over-discharge after the discharge of the rechargeable battery is stopped. It is characterized by doing.
According to such a configuration, it is possible to accurately detect the occurrence of turning poles.

Further, in the present invention, the second determination means is used when the internal resistance is constant or the terminal voltage changes abruptly as compared with the repolarization after the discharge of the rechargeable battery is stopped. Is characterized in that it is determined that an overdischarge has occurred.
According to such a configuration, inversion and overdischarge can be detected separately.

Further, the present invention is characterized in that when it is determined by the second determination means that a turning pole has occurred, a warning is given to the user.
According to such a configuration, it is possible to reliably inform the user of the occurrence of the turning pole.

Further, according to the present invention, when the rechargeable battery is mounted on a vehicle and it is determined by the second determination means that a turning pole has occurred, the engine of the vehicle is restarted. It is characterized by performing control to charge a rechargeable battery.
According to such a configuration, the state of turning pole can be reduced.

Further, according to the present invention, in the rechargeable battery state detecting method for detecting the state of the rechargeable battery, the voltage detecting unit for detecting the terminal voltage of the rechargeable battery and the current detecting unit for detecting the current flowing through the rechargeable battery When the rechargeable battery is discharging and the terminal voltage of the rechargeable battery is less than a predetermined threshold value based on the input step for inputting the signal of and the signal input in the input step, it is abnormal. If it is determined to be abnormal in the first determination step and the first determination step, after the discharge is stopped, the battery is rotated based on at least one of the change in the terminal voltage and the change in the internal resistance of the rechargeable battery. It is characterized by having a second determination step of determining the presence or absence of the occurrence of a pole.
According to such a method, it is possible to accurately detect the occurrence of turning poles.

According to the present invention, it is possible to provide a rechargeable battery state detecting device and a rechargeable battery state detecting method capable of accurately detecting the occurrence of inversion.

It is a figure which shows the structural example of the rechargeable battery state detection device which concerns on embodiment of this invention. It is a block diagram which shows the detailed configuration example of the control part of FIG. It is a figure which shows the change of the terminal voltage at the time of turning pole and over-discharging. It is a figure which shows the part of FIG. 3 enlarged. It is the figure which shows the change of the voltage and the change of the internal resistance at the time of a pole change and over-discharge in a simplified manner. This is an example of a flowchart for explaining the flow of processing executed while the engine is operating in the embodiment shown in FIG. This is an example of a flowchart for explaining the flow of processing executed after the engine is stopped in the embodiment shown in FIG.

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

(A) Explanation of Configuration of Embodiment of the Present Invention FIG. 1 is a diagram showing a power supply system of a vehicle having a rechargeable battery state detection device according to the embodiment of the present invention. In this figure, the rechargeable battery state detection device 1 has a control unit 10, a voltage detection unit 11, a current detection unit 12, a temperature detection unit 13, and a discharge circuit 15 as main components, and is a rechargeable battery 14. Control the charging status. The control unit 10, the voltage detection unit 11, the current detection unit 12, the temperature detection unit 13, and the discharge circuit 15 may not be configured separately, but may be partially or all of them. That is, the portion of the circuit in which the circuit for detecting the voltage is incorporated may be the voltage detection unit 11. Further, at least a part of the voltage detection unit 11, the current detection unit 12, the temperature detection unit 13, and the discharge circuit 15 may be configured independently of the rechargeable battery state detection device 1.

Here, the control unit 10 refers to the outputs from the voltage detection unit 11, the current detection unit 12, and the temperature detection unit 13, detects the state of the rechargeable battery 14, and controls the generated voltage of the alternator 16. This controls the charging state of the rechargeable battery 14. The voltage detection unit 11 detects the terminal voltage of the rechargeable battery 14 and notifies the control unit 10. The control unit 10 does not control the charging state of the rechargeable battery 14 by controlling the generated voltage of the alternator 16, but for example, an ECU (Electric Control Unit) (not shown) is based on the information from the control unit 10. The charging state may be controlled.

The current detection unit 12 detects the current flowing through the rechargeable battery 14 and notifies the control unit 10. The temperature detection unit 13 detects the rechargeable battery 14 itself or the ambient temperature, and notifies the control unit 10. The discharge circuit 15 is composed of, for example, a semiconductor switch and a resistance element connected in series, and the rechargeable battery 14 is intermittently discharged by controlling the semiconductor switch on / off by the control unit 10.

The rechargeable battery 14 is composed of, for example, a lead storage battery, a nickel cadmium battery, a nickel hydrogen battery, a lithium ion battery, or the like, is charged by the alternator 16, drives the starter motor 18, starts the engine, and loads 19. Power to. The alternator 16 is driven by the engine 17, generates AC power, converts it into DC power by a rectifier circuit, and charges the rechargeable battery 14. The alternator 16 is controlled by the control unit 10 so that the generated voltage can be adjusted.

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, is started by a starter motor 18, drives drive wheels via a transmission, gives propulsion to a vehicle, and is an alternator 16. To generate power. The starter motor 18 is composed of, for example, a DC motor, and generates a rotational force by the electric power supplied from the rechargeable battery 14 to start the engine 17. The load 19 is composed of, for example, an electric steering motor, a defogger, a seat heater, an ignition coil, a car audio, a car navigation system, and the like, and is operated by electric power from the rechargeable battery 14.

FIG. 2 is a diagram showing a detailed configuration example of the control unit 10 shown in FIG. As shown in this figure, the control unit 10 includes a CPU (Central Processing Unit) 10a as a processor, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, a communication unit 10d, and an I / F (Interface) 10e. have. Here, the CPU 10a controls each unit based on the program 10ba stored in the ROM 10b. The program 10ba has a plurality of instruction groups that can be executed by the CPU 10a. By executing the instruction group, the processing described later can be realized. The ROM 10b is composed of a semiconductor memory or the like and stores the program 10ba or the like. The RAM 10c is composed of a semiconductor memory or the like, and stores data generated when the program 10ba is executed and parameters 10ca such as mathematical formulas or tables described later. The communication unit 10d communicates with an ECU or the like which is a higher-level device, and notifies the higher-level device of the detected information or control information. The I / F 10e converts the signals supplied from the voltage detection unit 11, the current detection unit 12, and the temperature detection unit 13 into digital signals and captures them, and also informs the discharge circuit 15, the alternator 16, the starter motor 18, and the like. Drive currents are supplied to control these.

In the example of FIG. 2, one CPU 10a is provided, but the distributed processing may be executed by a plurality of CPUs. Further, instead of the CPU 10a, it may be configured by a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like. Alternatively, the processing may be performed on the computer on the server by a general-purpose processor or cloud computing that executes a function by loading a software program. Further, in FIG. 2, the ROM 10b and the RAM 10c are provided, but for example, a storage device other than these (for example, an HDD (Hard Disk Drive) which is a magnetic storage device) may be used.

(B) Description of Operation of Embodiment of the Present Invention Next, the operation of the embodiment of the present invention will be described. In the following, after explaining the operating principle of the embodiment of the present invention, detailed operation will be described.

First, the operating principle of this embodiment will be described. FIG. 3 is a diagram in which the temporal change of the terminal voltage (hereinafter, simply referred to as “voltage”) when a repolarization occurs during discharging of the rechargeable battery 14 and when an over-discharging occurs during discharging is measured. Is. In this figure, the horizontal axis represents time (hr) and the vertical axis represents the voltage of the rechargeable battery 14. Further, FIG. 4 is an enlarged view showing the range of 0 to 2.5 hr in FIG. 3 (the range surrounded by the alternate long and short dash line in FIG. 3).

In FIGS. 3 and 4, at time T0, when the discharge is stopped and the charge / discharge is not performed (in the case of a vehicle, the engine 17 is stopped), the solid line indicates an over-discharge (rechargeable battery 14). When the SOC becomes very low), the voltage recovers rapidly. Further, the amplitude of the voltage drop due to the discharge (impulses appearing periodically in FIGS. 3 and 4) by the discharge circuit 15 that is periodically executed is not large.

On the other hand, in the case of the inversion indicated by the broken line (when the positive electrode reaction and the charging reaction are reversed as a result of over-discharging), the voltage recovers more slowly than in the case of over-discharging. Further, the voltage drop due to the discharge (impulses appearing periodically in FIGS. 3 and 4) by the discharge circuit 15 executed periodically has a larger amplitude than the over-discharge. Since the discharge by the discharge circuit 15 that is periodically executed is a discharge by a constant current, a large amplitude of the voltage drop due to the discharge indicates that the internal resistance is large.

FIG. 5 is an image diagram showing a simplified change in voltage and a change in internal resistance at the time of repolarization and overdischarge. As shown by the solid line in FIG. 5, in the case of over-discharging, if the discharge is stopped at time T0 during the discharge, the voltage recovers rapidly. On the other hand, as shown by the broken line in FIG. 5, in the case of repolarization, if the discharge is stopped at time T0 during the discharge, the voltage recovers more slowly than in the case of over-discharge (the slope of the voltage is small).

Further, as shown by a white circle in FIG. 5, in the case of over-discharging, the value of the internal resistance becomes substantially constant when the discharge is stopped at time T0 during the discharge. On the other hand, as shown by black circles in FIG. 5, at the time of repolarization, when the discharge is stopped at time T0 during the discharge, the value of the internal resistance gradually decreases.

As shown above, when the discharge is stopped after the inversion occurs during the discharge, the voltage recovers more slowly than the over-discharge as shown by the broken line, and the internal resistance value gradually decreases. To do. On the other hand, when the discharge is stopped after the state of over-discharge during the discharge, the voltage recovers rapidly as shown by the solid line, and the internal resistance keeps a constant value.

Therefore, in the embodiment of the present invention, when the voltage drops below a predetermined threshold value while the rechargeable battery 14 is being discharged, it is first determined that repolarization or overdischarge has occurred, and the CPU 10a of the control unit 10 sets the flag. Set to the state of F = 1. Then, after the discharge is stopped (after the engine 17 is stopped), when the flag F = 1, the CPU 10a determines that a pole change or an overdischarge has occurred, and observes a change in voltage and a change in internal resistance. .. As a result, when the voltage recovers rapidly as shown by the solid line in FIG. 5 and the value of the internal resistance is constant as shown by the white circle, it is determined to be over-discharged. On the other hand, when the voltage gradually recovers as shown by the broken line in FIG. 5 and the value of the internal resistance decreases as shown by the black circle, it is determined that the pole is reversed.

As described above, in the present embodiment, when the voltage drops below a predetermined threshold value while the rechargeable battery 14 is being discharged, the voltage is not immediately determined, but is reduced after the discharge is stopped. If the internal resistance value is constant while recovering rapidly, it is judged as an over-discharge that can be recovered, and if the voltage recovers slowly and the internal resistance value decreases, it is difficult to recover. judge. Therefore, it is possible to prevent an overdischarge that can be restored from being erroneously determined as a turning electrode that is difficult to restore.

Next, an example of the processing executed in the embodiment of the present invention will be described with reference to FIGS. 6 to 7. FIG. 6 is a diagram showing a row of processes that are periodically executed, for example, when the engine 17 is in operation. When the processing of the flowchart shown in FIG. 6 is started, the following steps are executed.

In step S10, the CPU 10a of the control unit 10 determines whether or not the engine 17 is operating, and if it is determined that the engine 17 is operating (step S10: Y), the process proceeds to step S11, and in other cases (step S10: N) ends the process.

In step S11, the CPU 10a refers to the output of the current detection unit 12 and measures the current I flowing through the rechargeable battery 14.

In step S12, the CPU 10a refers to the current I measured in step S11, determines whether or not the rechargeable battery 14 is being discharged, and if it is determined that the rechargeable battery 14 is being discharged (step S12: Y), proceeds to step S13. , In other cases (step S12: N), the process ends.

In step S13, the CPU 10a refers to the output of the voltage detection unit 11 and measures the voltage (terminal voltage) V of the rechargeable battery 14.

In step S14, the CPU 10a compares the terminal voltage V of the rechargeable battery 14 measured in step S13 with a predetermined threshold value Th, and if V <Th is satisfied (step S14: Y), proceeds to step S15, and otherwise. In the case of (step S14: N), the process proceeds to step S16. When the rechargeable battery 14 is composed of 6 cells, the threshold value can be, for example, the voltage (for example, 10 V) when the voltage for one cell (about 2 V) is lower. .. Of course, a voltage other than this may be set.

In step S15, the CPU 10a assigns 1 to the flag F, which is set to 1 when an abnormality occurs in the rechargeable battery 14, and is set to 0 otherwise.

In step S16, the CPU 10a assigns 0 to the flag F.

By the above processing, when the terminal voltage V of the rechargeable battery 14 becomes less than the predetermined threshold value Th during discharging, the flag F is set to the state of 1 as if some abnormality has occurred, and the other state is set to 0. Will be done.

Next, with reference to FIG. 7, an example of processing executed when the engine 17 is stopped will be described. When the processing of the flowchart of FIG. 7 is started, the following steps are executed.

In step S30, the CPU 10a determines whether or not the engine 17 has been stopped, and if it determines that the engine 17 has been stopped (step S30: Y), the process proceeds to step S31, and in other cases (step S30: N). ) Ends the process.

In step S31, the CPU 10a determines whether or not the value of the flag F is 1, and if F = 1 (step S31: Y), the process proceeds to step S32, and in other cases (step S31: N). ) Ends the process.

In step S32, the CPU 10a sets 1 as an initial value in the variable n for counting the number of processes.

In step S33, the CPU 10a determines whether or not the predetermined time has elapsed, and if it is determined that the predetermined time has elapsed (step S33: Y), the process proceeds to step S34, and in other cases (step S33: N). ) Repeats the same process. For example, when several hours have passed, it is determined as Y and the process proceeds to step S34.

In step S34, the CPU 10a controls the discharge circuit 15 to pulse-discharge the rechargeable battery 14, for example.

In step S35, the CPU 10a measures the voltage V and the current I during discharging by the voltage detection unit 11 and the current detection unit 12.

In step S36, the CPU 10a stores the voltage V measured in step S35 in the array variable V (n). For example, when n = 1, the voltage V of the rechargeable battery 14 at that time is stored in V (1).

In step S37, the CPU 10a calculates the internal resistance R. More specifically, the CPU 10a calculates the internal resistance R of the rechargeable battery 14 from the changes in voltage and current during discharging.

In step S38, the CPU 10a stores the value of the internal resistance R calculated in step S37 in the array variable R (n). For example, when n = 1, the value of the internal resistance R of the rechargeable battery 14 at that time is stored in R (1).

In step S39, the CPU 10a increments the variable n for counting the number of processes by one.

In step S40, the CPU 10a determines whether or not the value of the variable n for counting the number of processes is larger than N, and if n> N is satisfied (step S40: Y), the process proceeds to step S41, and in other cases. In (Step S40: N), the process returns to step S33 and the same process as described above is repeated. As N, a value of about 2 to 20 can be set. Of course, other values may be set.

In step S41, the CPU 10a determines whether or not the value of V (n2) −V (n1) (where n2> n1) is a positive value (> 0), and if it is a positive value (step). In S41: Y), the process proceeds to step S42, and in other cases (step S41: N), the process ends.

In step S42, the CPU 10a determines that the value of V (n2) -V (n1) (where n2> n1) is less than a predetermined threshold value Th1 (when V (n2) -V (n1) <Th1). Determines that the voltage is slowly recovering after the discharge is stopped, as shown by the broken line in FIG. 5, and proceeds to step S43. The timings of n1 and n2 can be the timings of n1 and n2 shown in FIG. It is preferable that Th1 is set to a value smaller than the value of V (n2) -V (n1) at the time of over-discharging.

In step S43, when the CPU 10a determines whether or not the value of R (n) decreases with the passage of time as shown by a black circle in FIG. 5, and determines that the value of R (n) decreases with the passage of time ( In step S43: Y), the process proceeds to step S44, and in other cases (step S43: N), the process ends.

In step S44, the CPU 10a determines that the pole rotation has occurred. That is, when the terminal voltage V of the rechargeable battery 14 becomes less than a predetermined threshold value Th during discharging, the terminal voltage V gradually increases after the discharge is stopped, and the internal resistance R decreases, a repolarization occurs. Judge that there is.

In step S45, the CPU 10a outputs information indicating the occurrence of the pole rotation via the communication unit 10d. As a result, the upper ECU (Electric Control Unit) recognizes that the alternator has occurred, and for example, notifies the user of the occurrence of the alternator and warns the user, and when the engine 17 is started. For example, in order to eliminate the repolarization, the alternator 16 is controlled to charge the rechargeable battery 14 with a large current.

As described above, according to the processing of the flowchart shown in FIG. 7, if the terminal voltage becomes less than a predetermined threshold value Th while discharging the rechargeable battery 14, it is determined that an abnormality has immediately occurred. Instead, changes in voltage and internal resistance were detected after the discharge was stopped, and when the voltage gradually increased and the internal resistance decreased, it was determined that a turning pole had occurred. This makes it possible to prevent the recoverable over-discharge from being erroneously determined as a turning pole that is difficult to recover.

(C) Description of Modified Embodiment The above embodiment is an example, and it goes without saying that the present invention is not limited to the cases described above. For example, in the above embodiment, after the discharge is stopped, the presence or absence of the occurrence of inversion is determined by referring to both the internal resistance and the change in voltage, but one of these is used for the determination. You may. For example, if the internal resistance decreases after the discharge is stopped, it may be determined that the repolarization has occurred. Further, if the voltage gradually increases after the discharge is stopped, it may be determined that the repolarization has occurred.

Further, in the above embodiment, when a turning point occurs, the user is notified, but other processing may be executed. For example, at least one of (1) a process of notifying and warning the user of the occurrence of turning pole and (2) a process of changing the control of the vehicle may be executed.

More specifically, with respect to (1), when a pole change occurs, the CPU 10a of the control unit 10 outputs information indicating that the pole change has occurred to an ECU (not shown) via the communication unit 10d, and the ECU May display information indicating that a repolarization has occurred on a display device (not shown) and display information indicating that the rechargeable battery 14 needs to be replaced. In addition, a voice warning may be issued at the same time.

Regarding (2), when the CPU 10a of the control unit 10 outputs information indicating that a repolarization has occurred to an ECU (not shown) via the communication unit 10d, the rechargeable battery state detection device 1 can be charged. The state of the battery 14 (for example, SOF (State of Function)) is detected, and it is determined whether or not the engine 17 can be restarted. As a result, when it is determined that the engine 17 cannot be restarted, when the user tries to restart the engine 17, information indicating that the engine 17 cannot be restarted due to the rotation of the display device is displayed and the starter is displayed. The supply of current to the motor 18 is cut off.

On the other hand, when it is determined that the engine 17 can be restarted, the current (dark current) flowing through the load 19 is cut off in order to prevent further consumption of the rechargeable battery 14. Further, after the user starts the engine, the charging mode for repolarization can be entered, the generated voltage of the alternator 16 can be increased, and the rechargeable battery 14 can be controlled to be charged rapidly.

Further, it goes without saying that the flowcharts shown in FIGS. 6 to 7 are examples, and the present invention is not limited to these flowcharts.

For example, in the flowchart shown in FIG. 7, one determination in step S42 determines whether or not the curve is a broken line shown in FIG. 5, but in order not to cause an erroneous determination, a plurality of determinations are performed. You may do so. For example, when the slope of the voltage measured with the passage of time is ΔV1, ΔV2, ΔV3, ..., ΔVn, then ΔV1> ΔV2> ΔV3>, ..., ΔVn (the slope of the voltage is the passage of time). The average value of ΔV1, ΔV2, ΔV3, ..., ΔVn may be compared with a predetermined threshold value. Alternatively, each of ΔV1, ΔV2, ΔV3, ..., ΔVn may be compared with a predetermined threshold value whose value decreases with the passage of time. Of course, depending on the sampling timing, such a relationship may not always hold. Therefore, the sampling cycle may be appropriately determined, or the sampling cycle may be lengthened as the slope becomes smaller. Further, when a repolarization occurs, the inclination of ΔV continues even after a certain period of time has passed, as compared with the case of over-discharging. It may be determined that the pole is turned. Alternatively, if the time from reaching the predetermined voltage V1 to reaching the predetermined voltage V2 (> V1) is equal to or greater than the predetermined threshold value, it may be determined to be a repolarization. Further, these plurality of determination methods may be combined.

Further, the change in voltage may be fitted by a predetermined function, and the determination may be made based on the magnitude of the time constant of the function of the fitting result. For example, fitting may be performed by the exponential function shown in the following equation (1) or equation (2), and if the obtained time constant τ1 is equal to or greater than a predetermined threshold value, it may be determined to be a turning pole. In the equation (1), Time indicates the time, and in the equation (2), n indicates the number of samplings.

V = -A x exp (-Time / τ1) + B ... (1)

V = -A x exp (-n / τ1) + B ... (2)

Further, the threshold value may not be a fixed value, but may be made variable by, for example, temperature and / or SOC, or the threshold value may be calculated each time by temperature and / or SOC or the like.

Further, after the engine 17 is stopped, a dark current flows through the load 19. Therefore, the tendency of the voltage change may differ due to the influence of the dark current. Therefore, the threshold value is determined in consideration of the influence of dark current, the voltage value corrected for the influence of dark current is used, or the judgment is suspended when the dark current value is large. May be good.

Further, although the change in voltage has been described above, the change in resistance value can be similarly judged by using a plurality of threshold values, by fitting with a function and judging from a constant value, temperature and /. Alternatively, the threshold value may be obtained based on SOC or the like, or the influence of dark current may be taken into consideration.

More specifically, when the values of the internal resistance measured with the passage of time are R1, R2, R3, ..., Rn, then R1> R2> R3>, ..., Rn (of the internal resistance). (The value decreases with the passage of time), and when Rn gradually approaches a predetermined value as n increases, it may be determined to be a turning pole.

Alternatively, when the change in internal resistance is ΔR, each of ΔR1, ΔR2, ΔR3, ..., ΔRn may be compared with the threshold value at which the value approaches 0 from minus with the passage of time. Of course, depending on the sampling timing, such a relationship may not always hold. Therefore, the sampling cycle may be appropriately determined, or the sampling cycle may be lengthened as the slope approaches zero. Alternatively, if the time from reaching the predetermined internal resistance R1 to reaching the predetermined internal resistance R2 (<R1) is less than the predetermined threshold value, it may be determined to be a turning pole.

Further, the change in the internal resistance may be fitted by a predetermined function, and the determination may be made based on the magnitude of the time constant of the function of the fitting result. For example, fitting may be performed by an exponential function shown in the following equation (3) or equation (4), and for example, when the obtained constant C + D is equal to or greater than a predetermined threshold value, it may be determined to be a turning pole. Alternatively, if C is equal to or greater than a predetermined threshold value, it may be determined to be a turning pole. Alternatively, when the time constant τ2 is less than a predetermined threshold value, it may be determined as a turning pole. In the equation (3), Time indicates the time, and in the equation (4), n indicates the number of samplings.

R = C × exp (−Time / τ2) + D ・ ・ ・ (3)

R = C × exp (−n / τ2) + D ・ ・ ・ (4)

Further, the threshold value for determination is not a fixed value as in the case of voltage, but is variable depending on, for example, temperature and / or SOC, or the threshold value is calculated each time based on temperature and / or SOC. It may be obtained by.

Further, as in the case of the voltage described above, after the engine 17 is stopped, a dark current flows through the load 19. Therefore, the tendency of the change in the internal resistance may differ depending on the influence of the dark current. Therefore, the threshold value may be determined in consideration of the influence of the dark current, or the determination may be suspended when the value of the dark current is large.

1 Rechargeable battery status detector 10 Control unit 10a CPU
10b ROM
10c RAM
10d communication unit 10e I / F
11 Voltage detector 12 Current detector 13 Temperature detector 14 Rechargeable battery 15 Discharge circuit 16 Alternator 17 Engine 18 Starter motor 19 Load

Claims (7)

In the rechargeable battery status detector that detects the status of the rechargeable battery,
An input means for inputting a signal from a voltage detection unit that detects the terminal voltage of the rechargeable battery and a current detection unit that detects the current flowing through the rechargeable battery.
Based on the signal input from the input means, the first determination means for determining that the rechargeable battery is abnormal when the terminal voltage of the rechargeable battery is less than a predetermined threshold value when the rechargeable battery is being discharged. When,
When an abnormality is determined by the first determination means, after the discharge is stopped, a second determination is made to determine whether or not a repolarization occurs based on at least one of a change in the terminal voltage and a change in the internal resistance of the rechargeable battery. Means and
A rechargeable battery state detector characterized by having. The rechargeable battery state according to claim 1, wherein the second determination means determines that a repolarization has occurred when the internal resistance decreases after the discharge of the rechargeable battery is stopped. Detection device. The second determination means is characterized in that, when the terminal voltage gradually increases as compared with the case of over-discharge after the discharge of the rechargeable battery is stopped, it is determined that a repolarization has occurred. The rechargeable battery state detection device according to claim 1 or 2. In the second determination means, over-discharging occurs when the internal resistance is constant or the terminal voltage changes abruptly as compared with the inversion pole after the discharge of the rechargeable battery is stopped. The rechargeable battery state detecting device according to any one of claims 1 to 3, wherein it is determined that the battery has been discharged. The rechargeable battery state according to any one of claims 1 to 4, wherein when it is determined by the second determination means that a turning pole has occurred, a warning is given to the user. Detection device. The rechargeable battery is mounted on the vehicle and
When it is determined by the second determination means that the repolarization has occurred, the control for charging the rechargeable battery is executed when the engine of the vehicle is restarted.
The rechargeable battery state detecting device according to any one of claims 1 to 5, wherein the rechargeable battery state detecting device. In the rechargeable battery status detection method for detecting the status of a rechargeable battery,
An input step for inputting signals from a voltage detection unit that detects the terminal voltage of the rechargeable battery and a current detection unit that detects the current flowing through the rechargeable battery.
Based on the signal input in the input step, the first determination step of determining that the rechargeable battery is abnormal when the terminal voltage of the rechargeable battery is less than a predetermined threshold value when the rechargeable battery is being discharged. When,
When an abnormality is determined in the first determination step, after the discharge is stopped, a second determination is made to determine whether or not a repolarization has occurred based on at least one of a change in the terminal voltage and a change in the internal resistance of the rechargeable battery. Steps and
A rechargeable battery state detector characterized by having.