JP2008021417A - Battery pack and detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve accuracy of detecting failure in a battery pack and prevent defects by detecting the failure. <P>SOLUTION: The voltage of a secondary battery is measured for every prescribed time and voltage fluctuation amount in the prescribed time is calculated. The voltage fluctuation amount and an upper limit value to the voltage fluctuation amount stored in a memory part beforehand are compared at every prescribed time, and when the case in which the voltage fluctuation amount becomes larger than the upper limit value continues for a prescribed number of times, it is determined to be failed. When the case in which voltage fluctuation amount becomes larger than the upper limit value does not continue for the prescribed number of times, a new upper limit value is calculated based on the voltage fluctuation amount. Nextly, the voltage fluctuation amount and a lower limit value to the voltage fluctuation amount stored in a memory part beforehand are compared at every prescribed time, and when the case in which the voltage fluctuation amount becomes smaller than the lower limit value continues for a prescribed number of times, it is determined to be failed. Then, when the case in which the voltage fluctuation amount becomes smaller than the lower limit value does not continue for the prescribed number of times. a new lower limit value is calculated based on the voltage fluctuation amount. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery pack for detecting an abnormality and a detection method thereof.

  In recent years, portable electronic devices such as notebook PCs (Personal Computers), cellular phones, and PDAs (Personal Digital Assistants) have become widespread, and lithium-ion secondary batteries having advantages such as high voltage, high energy density, and light weight as their power sources. Widely used.

  Conventional battery packs of secondary batteries include a measurement circuit that measures charge / discharge current, charge / discharge voltage, battery temperature, and the like, and MPU (Micro Processing) that controls charge / discharge of the secondary battery based on the measurement results of the measurement circuit. Unit) and other control circuits are installed. The control circuit detects abnormalities such as overcharge, overdischarge, overcurrent, and temperature abnormality based on the measurement result of the measurement circuit.

  Thus, a method for detecting an abnormality of a battery pack based on various measured information is described in Patent Document 1 below.

JP 2001-110457 A

  In general, it is known that when an abnormality occurs in a battery pack, the voltage and temperature of the battery cell rapidly increase. Therefore, it is possible to determine whether or not an abnormality has occurred in the battery pack based on the voltage or temperature increase degree within a predetermined time.

  Specifically, for example, a threshold is set in advance for the amount of fluctuation in voltage or temperature, and the amount of fluctuation is calculated based on the voltage or temperature measured every predetermined time. Then, the calculated fluctuation amount of the voltage or temperature is compared with a set threshold value, and if the fluctuation amount exceeds the threshold value, it is determined that an abnormality has occurred in the battery pack.

  However, for example, when an electronic device using this battery pack is a device that generates radio waves such as a mobile phone, the generated radio waves may be superimposed on voltage or temperature as noise. Thus, even when noise generated inside the battery pack or noise from outside is superimposed on the voltage or temperature, the voltage or temperature rises instantaneously. For this reason, if the abnormality of the battery pack is determined based on the voltage or temperature increase degree within a predetermined time, it is determined that the battery pack is abnormal even if noise is superimposed in this way, and erroneous detection may occur. There was a problem that there was.

  Further, the abnormality detection is performed in the conventional battery pack after a failure occurs in the secondary battery. That is, there is a problem in that there is no method for preventing a failure of the secondary battery based on the detection result.

  Accordingly, an object of the present invention is to provide a battery pack capable of improving the accuracy of detecting an abnormality, detecting the abnormality, and preventing a malfunction, and a method for detecting the battery pack.

  In order to solve the above-described problem, the first invention provides one or a plurality of secondary batteries, a measuring unit that measures the voltage of the secondary battery every predetermined time, and a voltage fluctuation amount within a predetermined time based on the voltage. A control unit that controls charging / discharging of the secondary battery based on the voltage fluctuation amount, a specified voltage fluctuation amount with respect to the voltage fluctuation amount, and an upper limit number indicating the upper limit of the number of times that the voltage fluctuation amount exceeds the specified voltage fluctuation amount. The control unit compares the voltage fluctuation amount with the specified voltage fluctuation amount every predetermined time. When the voltage fluctuation amount exceeds the specified voltage fluctuation amount, the control unit is provided in advance in the storage unit. The battery pack is characterized in that when the counter value is incremented and the counter value is equal to or greater than the upper limit number of times, it is determined to be abnormal.

  Further, the second invention calculates one or a plurality of secondary batteries, a measuring unit that measures the ambient temperature of the secondary battery every predetermined time, calculates a temperature fluctuation amount within a predetermined time based on the ambient temperature, A control unit that controls charging / discharging of the secondary battery based on the fluctuation amount, and a storage unit that stores an upper limit value for the temperature fluctuation amount and an upper limit number indicating the upper limit of the number of times the temperature fluctuation amount is larger than the upper limit value. The control unit compares the temperature fluctuation amount with the upper limit value every predetermined time. If the temperature fluctuation amount is larger than the upper limit value, the control unit increments a counter value provided in advance in the storage unit, When the battery pack number exceeds the upper limit, the battery pack is characterized as being abnormal.

  Further, the third invention is a measurement step for measuring the voltage of one or a plurality of secondary batteries every predetermined time, calculates a voltage fluctuation amount within a predetermined time based on the voltage, and calculates the voltage fluctuation amount every predetermined time. The voltage fluctuation amount stored in the storage unit is compared with the specified voltage fluctuation amount. If the voltage fluctuation amount exceeds the specified voltage fluctuation amount, the counter value provided in advance in the storage unit is incremented. A control step of determining that the value is abnormal when the value is equal to or greater than an upper limit number indicating the upper limit of the number of times the voltage fluctuation amount provided in advance in the storage unit exceeds the specified voltage fluctuation amount. It is a detection method.

  According to a fourth aspect of the present invention, there is provided a measurement step for measuring the ambient temperature of one or a plurality of secondary batteries every predetermined time, a temperature fluctuation amount within a predetermined time is calculated based on the ambient temperature, and the temperature fluctuation is performed every predetermined time. When the temperature fluctuation amount is larger than the upper limit value, the counter value provided in the storage unit is incremented and the value of the counter is compared. And a control step for determining that the temperature fluctuation amount provided in the storage unit is abnormal when the temperature fluctuation amount is equal to or greater than the upper limit number indicating the upper limit of the number of times greater than the upper limit value. It is.

  As described above, in the first and third aspects of the invention, the voltage fluctuation amount is compared with the specified voltage fluctuation amount with respect to the voltage fluctuation amount stored in the storage unit every predetermined time, and the voltage fluctuation amount is determined as the specified voltage fluctuation amount. Since the counter value provided in the storage unit is incremented when the value exceeds the upper limit of the number of times that the voltage fluctuation amount provided in the storage unit exceeds the specified voltage fluctuation amount. When the number of times is equal to or greater than the upper limit number of times, it is determined that there is an abnormality.

  In the second and fourth inventions, the temperature fluctuation amount is compared with the upper limit value for the temperature fluctuation amount stored in the storage unit every predetermined time, and when the temperature fluctuation amount is larger than the upper limit value, Since the value of the counter provided in advance in the storage unit is incremented, the value of the counter becomes equal to or greater than the upper limit number indicating the upper limit of the number of times that the temperature fluctuation amount provided in advance in the storage unit is greater than the upper limit value. In the case, it is determined to be abnormal.

  The present invention calculates a fluctuation amount within a predetermined time based on the voltage of the secondary battery and the ambient temperature measured every predetermined time, calculates a prescribed fluctuation amount with respect to the fluctuation amount, In order to determine whether or not an abnormality has occurred based on whether or not the fluctuation amount exceeds the specified fluctuation amount more than a predetermined number of times, it is possible to immediately detect the abnormality of the battery pack and There is an effect that it can be prevented.

  Further, according to the present invention, when the fluctuation amount does not exceed the specified fluctuation amount for a predetermined number of times, the specified fluctuation amount is newly updated based on the fluctuation amount, and the updated new specified fluctuation amount is compared with the fluctuation amount. Thus, the abnormality detection accuracy can be improved.

  Hereinafter, a battery pack 1 according to an embodiment of the present invention will be described with reference to FIG. When the electronic device is used, the battery pack 1 has the positive electrode terminal 11 and the negative electrode terminal 12 connected to the positive electrode terminal and the negative electrode terminal of the electronic device, respectively, and is discharged. Also, the battery is mounted on the charger during charging, and the positive electrode terminal 11 and the negative electrode terminal 12 are connected to the positive electrode terminal and the negative electrode terminal of the charger, respectively, as in the case of using the electric device, and charging is performed.

  The battery pack 1 mainly includes a battery cell 17, a temperature detection element 18, an AFE (Analog Front End) 20, an MPU (Micro Processing Unit) 21, a switch circuit 14, and communication terminals 13a and 13b. The battery cell 17 is, for example, a secondary battery of a lithium ion battery, and one or a plurality of secondary batteries are connected in series and / or in parallel.

  The temperature detection element 18 is provided in the vicinity of the battery cell 17 and detects the temperature around the battery cell 17. As the temperature detection element 18, for example, a thermistor whose resistance value varies with temperature can be used, and the temperature of the battery cell 17 can be detected by measuring the voltage of the thermistor.

  The AFE 20 measures the voltage of each battery cell 17 in the battery pack 1 and supplies the measured value to the MPU 21. Further, the AFE 20 measures the magnitude and direction of the current using the current detection resistor 19 and supplies the measured value to the MPU 21. Further, the AFE 20 measures the voltage of the temperature detection element 18, converts the measured voltage of the temperature detection element 18 into a temperature, and supplies the temperature to the MPU 21. These various measurements are performed every predetermined time.

  The AFE 20 prevents overcharge and overdischarge by sending a control signal to the switch circuit 14 based on a command from the MPU 21. Here, when the battery cell 17 is a lithium ion battery, the overcharge detection voltage is determined to be, for example, 4.2 V ± 0.5 V, and the overdischarge detection voltage is determined to be 2.4 V ± 0.1 V.

  The MPU 21 detects abnormality of the battery cell 17 based on the voltage and temperature of the battery cell 17 supplied from the AFE 20. Information obtained by abnormality detection is stored in a nonvolatile memory 22 built in the MPU 21. As the nonvolatile memory 22, for example, an EEPROM (Electrically Erasable and Programmable Read Only Memory) can be used. Note that the nonvolatile memory 22 is not limited to the one built in the MPU 21, and may be provided outside the MPU 21, for example. The information obtained by the abnormality detection stored in the nonvolatile memory 22 is used for analysis of defects when the battery pack 1 is recovered, for example.

  Further, the MPU 21 determines whether the voltage of any one of the battery cells 17 becomes an overcharge detection voltage based on the voltage value and the current value supplied from the AFE 20, or the voltage of the battery cell 17 is equal to or lower than the overdischarge detection voltage. In this case, a command for controlling the switch circuit 14 is supplied to the AFE 20.

  The switch circuit 14 includes a charge control FET (Field Effect Transistor) 15 and a discharge control FET 16. When the battery voltage becomes the overcharge detection voltage, the charge control FET 15 is turned off and the charging current is controlled not to flow. Note that after the charge control FET 15 is turned off, only discharge is possible via the parasitic diode 15a.

  Further, when the battery voltage becomes the overdischarge detection voltage, the discharge control FET 16 is turned off, and the discharge current is controlled not to flow. Note that after the discharge control FET 16 is turned off, only charging is possible through the parasitic diode 16a.

  When the communication terminals 13a and 13b are attached to an electronic device such as a mobile phone, the communication terminals 13a and 13b transmit various information such as information indicating an abnormality of the battery pack 1 to the electronic device based on a predetermined communication protocol.

  In the above-described configuration, the AFE 20 and the MPU 21 are described as independent from each other, but this is not limited to this example. For example, the AFE 20 and the MPU 21 may be integrated.

  Next, a method for detecting an abnormality of the battery pack 1 will be described with reference to FIGS. The voltage and temperature of the battery cell 17 are substantially constant when the battery pack 1 is operating normally. However, when an abnormality occurs in the battery pack 1, the voltage or temperature of the battery cell 17 rapidly increases. Ascend or descend.

  On the other hand, even when noise or the like is superimposed on the voltage or temperature of the battery cell 17 measured by the AFE 20, the voltage or temperature rapidly rises or falls. In this case, the voltage or temperature rises or falls. , Momentary. Therefore, in such a case, the increased or decreased voltage immediately decreases or increases and becomes a normal voltage.

  Therefore, in one embodiment of the present invention, attention is paid to the rise or fall of the voltage or temperature of the battery cell 17 measured by the AFE 20, and the fluctuation amount is calculated based on the voltage or temperature measured every predetermined time. To do. Then, the abnormality of the battery pack 1 is detected based on whether or not the calculated fluctuation amount exceeds a predetermined upper limit value or lower limit value of the voltage or temperature fluctuation amount continuously a predetermined number of times.

  First, the values set in the nonvolatile memory 22 of the MPU 21 will be described more specifically. With respect to the voltage fluctuation amount ΔV within a predetermined time, the upper limit value ΔV (+ limit) of the voltage fluctuation amount within the predetermined time, the lower limit value ΔV (−limit) of the voltage fluctuation amount, and the voltage fluctuation amount ΔV are set to the upper limit value ΔV ( The first upper limit number K (+) indicating the upper limit of the number of times equal to or greater than + limit), and the second upper limit number K (-) indicating the upper limit of the number of times that the voltage fluctuation amount ΔV is equal to or less than the lower limit value ΔV (−limit). Set. Further, a first counter K (+ cnt) that counts the number of times that the voltage fluctuation amount ΔV is equal to or greater than the upper limit value, and a second counter K (−cnt) that counts the number of times that the voltage fluctuation amount ΔV is equal to or less than the lower limit value Provide.

  Note that the upper limit value ΔV (+ limit) is a positive value, for example, a value larger than a fluctuation amount that can be normally taken is set. Further, the lower limit value ΔV (−limit) is a negative value, and, for example, a value smaller than the fluctuation amount that can be normally taken is set, similarly to the upper limit value ΔV (+ limit).

Next, the abnormality detection operation based on the voltage fluctuation amount of the battery cell 17 will be described in detail. As shown in FIG. 2A, when an abnormality occurs in the battery pack 1, the voltage of the battery cell 17 rapidly increases. As shown in FIG. 2B in which the portion surrounded by the dotted line shown in FIG. 2A is enlarged, the voltage of the battery cell 17 at time A at time M (n−1) is V (n−1), and a predetermined time from time A. The voltage of the battery cell 17 at the time point B at time M (n) after elapses is defined as V (n). The voltage fluctuation amount ΔV (n) from time A to time B at this time is calculated based on Equation (1).
ΔV (n) = V (n) −V (n−1) (1)

  The voltage fluctuation amount ΔV (n) calculated as described above is compared with the preset upper limit value ΔV (+ limit) and lower limit value ΔV (−limit) of the voltage fluctuation amount. As a result of the comparison, when the value of the voltage fluctuation amount ΔV (n) becomes equal to or larger than the upper limit value ΔV (+ limit), the value of the first counter K (+ cnt) is incremented by “1”. Further, when the value of the voltage fluctuation amount ΔV (n) becomes equal to or lower than the lower limit value ΔV (−limit), the value of the second counter K (−cnt) is incremented by “1”. In this case, the voltage fluctuation amount ΔV (n), the values of the first counter K (+ cnt), and the second counter K (−cnt) are stored in the nonvolatile memory 22.

  Next, the value of the first counter K (+ cnt) is compared with the value of the first upper limit number K (+). As a result of the comparison, when the value of the first counter K (+ cnt) is equal to or greater than the value of the first upper limit number K (+), it is determined that the battery cell 17 is abnormal, and abnormality processing is performed. Similarly, the value of the second counter K (−cnt) is compared with the value of the second upper limit number of times K (−). As a result of the comparison, when the value of the second counter K (−cnt) becomes equal to or greater than the value of the second upper limit number K (−), it is determined that the battery cell 17 is abnormal, and an abnormal process is performed. . As the abnormal process, for example, the charge / discharge control FET is turned off to interrupt the charge / discharge current to the battery cell 17.

  In addition, when the value of the first counter K (+ cnt) is smaller than the value of the first upper limit number K (+), and the value of the second counter K (−cnt) is equal to the second upper limit number K (− ), The upper limit value ΔV (+ limit) and the lower limit value ΔV (−limit) of the voltage fluctuation amount are calculated again based on the voltage fluctuation amount ΔV (n) and stored in the nonvolatile memory 22. Is done. The newly calculated upper limit value ΔV (+ limit) is initially set to a value smaller than the upper limit value stored in the nonvolatile memory 22, and the newly calculated lower limit value ΔV (−limit) is A value larger than the lower limit value stored in the nonvolatile memory 22 is set.

  Specifically, for example, the newly calculated upper limit value ΔV (+ limit) of the voltage fluctuation amount is a value that is about 40% to 60% smaller than the upper limit value ΔV (+ limit) of the initial voltage fluctuation amount. For example, the value of the lower limit value ΔV (−limit) of the newly calculated voltage fluctuation amount set to a value smaller by 0.2V is 40% than the value of the lower limit value ΔV (−limit) of the initial voltage fluctuation amount. It is set to a value that is larger by about 60%, for example, a value that is 0.2V larger.

Next, in the same manner as described above, the voltage fluctuation amount ΔV (n + 1) from the time point B to the time point C is based on the voltage V (n + 1) at the time point C which is the time M (n + 1) after a predetermined time has elapsed from the time point B. Is calculated based on Equation (2).
ΔV (n + 1) = V (n + 1) −V (n) (2)

  The calculated voltage fluctuation amount ΔV (n + 1) is compared with the newly calculated upper limit value ΔV (+ limit) and lower limit value ΔV (−limit) of the voltage fluctuation amount. As a result of the comparison, when the value of the voltage fluctuation amount ΔV (n + 1) becomes equal to or larger than the upper limit value ΔV (+ limit), the value of the first counter K (+ cnt) is incremented by “1”. When the value of the voltage fluctuation amount ΔV (n + 1) becomes equal to or lower than the lower limit value ΔV (−limit), the value of the second counter K (−cnt) is incremented by “1”. In this case, values of the voltage fluctuation amount ΔV (n + 1), the first counter K (+ cnt), and the second counter K (−cnt) are stored in the nonvolatile memory 22.

  Such processing is performed every predetermined time, and the first counter K (+ cnt) and the second counter K (−), the first upper limit number K (+), and the second upper limit number K (−). To determine whether or not the battery cell 17 is abnormal, and normal processing or abnormal processing is performed according to the determination result.

  When the value of the voltage fluctuation amount ΔV (n) is smaller than the upper limit value ΔV (+ limit) of the voltage fluctuation amount, and the value of the voltage fluctuation amount ΔV (n) is the lower limit value of the voltage fluctuation amount. In any case where the value is larger than the value of ΔV (−limit), the values of the first counter K (+ cnt) and the second counter K (−cnt) are reset to “0”. The upper limit value ΔV (+ limit) and the lower limit value ΔV (−limit) of the voltage fluctuation amount are returned to the values stored in the nonvolatile memory 22 first.

  Thus, the voltage fluctuation amount ΔV (n) is compared with the upper limit value ΔV (+ limit) and the lower limit value ΔV (−limit), and the voltage fluctuation amount ΔV (n) is equal to or higher than the upper limit value ΔV (+ limit) or the lower limit value ΔV. When the voltage fluctuation amount ΔV (n) is equal to or higher than the upper limit value ΔV (+ limit) or lower than the lower limit value ΔV (−limit) is equal to or greater than a preset number of times, the battery It can be determined that the pack 1 is abnormal.

  When the voltage fluctuation amount ΔV (n) is equal to or higher than the upper limit value ΔV (+ limit) or lower than the lower limit value ΔV (−limit), the upper limit value ΔV (+ limit) and the lower limit value ΔV (−limit) are newly set. By calculating and setting an upper limit value ΔV (+ limit) that is smaller than the upper limit value before calculation and a lower limit value ΔV (−limit) that is greater than the lower limit value before calculation, the values of the upper limit value and the lower limit value are set. The range is narrowed, and an abnormality can be detected with higher accuracy.

  Next, the abnormality detection method based on the temperature fluctuation amount of the battery cell 17 will be described in detail with reference to FIG. As shown in FIG. 3A, when an abnormality occurs in the battery pack 1, the temperature of the battery cell 17 rapidly rises.

  The upper limit value ΔT (+ limit) of the temperature fluctuation amount within the predetermined time and the upper limit of the number of times that the temperature fluctuation amount ΔT (n) is equal to or higher than the upper limit value ΔT (+ limit) with respect to the temperature fluctuation amount ΔT within the predetermined time. An upper limit number K ′ (+) to be shown is set in advance. Further, a counter K ′ (+ cnt) is provided for counting the number of times that the temperature fluctuation amount ΔT is equal to or greater than the upper limit value.

As shown in FIG. 3B in which the portion surrounded by the dotted line shown in FIG. 3A is enlarged, the temperature of the battery cell 17 at time A ′ at time M ′ (n−1) is defined as T (n−1). Further, the temperature of the battery cell 17 at time B ′ at time M ′ (n) after a predetermined time has elapsed from time A is defined as T (n). At this time, the temperature fluctuation amount ΔT (n) from the time point A ′ to the time point B ′ is calculated based on the equation (3).
ΔT (n) = T (n) −T (n−1) (3)

  The temperature fluctuation amount ΔT (n) calculated as described above is compared with a preset upper limit value ΔT (+ limit) of the temperature fluctuation amount. As a result of the comparison, if the value of the temperature fluctuation amount ΔT (n) becomes equal to or greater than the upper limit value ΔT (+ limit), the value of the counter K ′ (+ cnt) is incremented by “1”. In this case, the temperature fluctuation amount ΔT (n) and the value of the counter K ′ (+ cnt) are stored in the nonvolatile memory 22.

  Next, the value of the counter K ′ (+ cnt) is compared with the value of the upper limit number K ′ (+). As a result of the comparison, when the value of the counter K ′ (+ cnt) becomes equal to or greater than the value of the upper limit number K ′ (+), it is determined that the battery pack 17 is abnormal and abnormal processing is performed. As the abnormal process, for example, the charge / discharge control FET is turned off to interrupt the charge / discharge current to the battery cell 17.

  When the value of the counter K ′ (+ cnt) is smaller than the value of the upper limit number K ′ (+), the value of the upper limit value ΔT (+ limit) of the temperature fluctuation amount is calculated again based on the temperature fluctuation amount ΔT (n). And stored in the nonvolatile memory 22. The newly calculated upper limit value ΔT (+ limit) is set to a value smaller than the upper limit value stored in the nonvolatile memory 22. Specifically, for example, the newly calculated upper limit value ΔT (+ limit) of the temperature fluctuation amount is set to a value 0.5 ° C. smaller than the initial upper limit value ΔT (+ limit) of the temperature fluctuation amount. Is done.

Next, in the same manner as described above, based on the temperature T (n + 1) at the time point C ′, which is the time M ′ (n + 1) after the lapse of a predetermined time from the time point B ′, the temperature fluctuation from the time point B ′ to the time point C ′. The amount ΔT (n + 1) is calculated based on Equation (4).
ΔT (n + 1) = T (n + 1) −T (n) (4)

  The temperature fluctuation amount ΔT (n + 1) calculated as described above is compared with the newly calculated upper limit value ΔT (+ limit) of the temperature fluctuation amount. As a result of the comparison, when the value of the temperature fluctuation amount ΔT (n + 1) becomes equal to or larger than the upper limit value ΔT (+ limit), the value of the counter K ′ (+ cnt) is incremented by “1”. In this case, the temperature fluctuation amount ΔT (n + 1) and the value of the counter K ′ (+ cnt) are stored in the nonvolatile memory 22.

  When the value of the temperature fluctuation amount ΔT (n) is smaller than the value of the upper limit value ΔT (+ limit) of the temperature fluctuation amount, the value of the counter K ′ (+ cnt) is reset to “0”. The upper limit value ΔT (+ limit) of the temperature fluctuation amount is returned to the value stored in the nonvolatile memory 22 first.

  Thus, the temperature fluctuation amount ΔT (n) is compared with the upper limit value ΔT (+ limit), the temperature fluctuation amount ΔT (n) is equal to or greater than the upper limit value ΔT (+ limit), and the temperature fluctuation amount ΔT (n) is further increased. When the state that is equal to or greater than the upper limit value ΔT (+ limit) is equal to or greater than the preset number of times, it can be determined that the battery pack 1 is abnormal.

  When the temperature fluctuation amount ΔT (n) becomes equal to or greater than the upper limit value ΔT (+ limit), a new upper limit value ΔT (+ limit) is calculated, and the upper limit value ΔT ( By setting (+ limit), the range of the upper limit value is narrowed, and an abnormality can be detected with higher accuracy.

  In this way, the voltage or temperature fluctuation amount of the battery cell 17 is compared with the upper limit value and lower limit value of the fluctuation amount, and the number of times that the voltage or temperature fluctuation amount exceeds the upper limit value and the lower limit value is determined. Thus, the abnormality of the battery cell 17 can be detected with higher accuracy. This abnormality detection process may be performed for both voltage and temperature, and may be determined to be abnormal when an abnormality is detected in either one. Further, the present invention is not limited to this, and for example, the abnormality detection process may be performed for only one of voltage and temperature.

  Next, the flow of processing in the MPU 21 when an abnormality is detected by the voltage of the battery cell 17 will be described using the flowchart shown in FIG. In the following, it is assumed that processing is performed by the MPU 21 unless otherwise specified. Here, the measurement of the voltage of the battery cell 17 shall be performed continuously for every predetermined time. Further, an upper limit value ΔV (+ limit), a lower limit value ΔV (−limit), a first upper limit number K (+), and a second upper limit number K (−) of the voltage fluctuation amount are set in advance, and are provided in, for example, the MPU 21. The data is stored in the nonvolatile memory 22 or the like.

  First, in step S1, the voltage fluctuation amount ΔV (n) is calculated based on the voltage V (n−1) at time M (n−1) and the voltage V (n) at time M (n) after a predetermined time has elapsed. calculate.

  In step S2, the voltage fluctuation amount ΔV (n) calculated in step S1 is compared with a preset voltage fluctuation amount upper limit value ΔV (+ limit). As a result of the comparison, if the voltage fluctuation amount ΔV (n) is equal to or less than the upper limit value ΔV (+ limit), the process proceeds to step S3. In step S3, the upper limit value ΔV (+ limit) of the voltage fluctuation amount is returned to the initially stored value, and the value of the first counter K (+ cnt) is set to “0”.

  On the other hand, when the voltage fluctuation amount ΔV (n) is larger than the upper limit value ΔV (+ limit) as a result of the comparison in step S2, the process proceeds to step S4. In step S4, the value of the first counter K (+ cnt) is incremented by “1”. Further, the voltage fluctuation amount ΔV (n) and the value of the first counter K (+ cnt) at this time are stored in the nonvolatile memory 22. In the case where the voltage fluctuation amount ΔV (n) is already stored in the nonvolatile memory 22, the larger one of the two voltage fluctuation amounts ΔV (n) is stored.

  In step S5, the value of the first counter K (+ cnt) is compared with a preset first upper limit number K (+). As a result of the comparison, if the value of the first counter K (+ cnt) is smaller than the first upper limit number K (+), it is determined that the battery pack 1 is normal, and the process proceeds to step S6. In step S6, an upper limit value ΔV (+ limit) of the voltage fluctuation amount is newly calculated based on the voltage fluctuation amount ΔV (n), and the process proceeds to step S7.

  On the other hand, when the value of the first counter K (+ cnt) is equal to or larger than the first upper limit number K (+) as a result of the comparison in step S5, it is determined that the battery pack 1 is abnormal, and the process is performed. The process proceeds to step S13.

  In step S7, the voltage fluctuation amount ΔV (n) is compared with a preset lower limit value ΔV (−limit) of the voltage fluctuation amount. As a result of the comparison, if the voltage fluctuation amount ΔV (n) is greater than or equal to the lower limit value ΔV (−limit), the process proceeds to step S8. In step S8, the lower limit value ΔV (−limit) of the voltage fluctuation amount is returned to the initially stored value, and the value of the second counter K (−cnt) is set to “0”.

  On the other hand, when the voltage fluctuation amount ΔV (n) is smaller than the lower limit value ΔV (−limit) as a result of the comparison in step S7, the process proceeds to step S9. In step S9, the value of the second counter K (−cnt) is incremented by “1”. Further, the voltage fluctuation amount ΔV (n) and the value of the second counter K (−cnt) at this time are stored in the nonvolatile memory 22. In the case where the voltage fluctuation amount ΔV (n) is already stored in the nonvolatile memory 22, the larger one of the two voltage fluctuation amounts ΔV (n) is stored.

  In step S10, the value of the second counter K (-cnt) is compared with a preset second upper limit number K (-). As a result of the comparison, if the value of the second counter K (−cnt) is smaller than the second upper limit number K (−), it is determined that the battery pack 1 is normal, and the process proceeds to step S11. In step S11, a lower limit value ΔV (−limit) of the voltage fluctuation amount is newly calculated based on the voltage fluctuation amount ΔV (n), and the process proceeds to step S12.

  On the other hand, if the value of the second counter K (-cnt) is equal to or greater than the second upper limit number K (-) as a result of the comparison in step S10, it is determined that the battery pack 1 is abnormal, and the process Goes to step S13.

  In step S12, it is determined that the battery pack 1 is normal, normal processing is performed, the processing returns to step S1, and a series of processing is cyclically repeated every predetermined time.

  In step S13, for example, an abnormal process is performed in which the charge control FET 15 and the discharge control FET 16 are turned off by the control of the AFE 20 to prohibit charging / discharging of the battery cell 17, and the series of processes ends.

  Next, the flow of processing in the MPU 21 at the time of detecting an abnormality due to the temperature of the battery cell 17 will be described using the flowchart shown in FIG. In the following, it is assumed that processing is performed by the MPU 21 unless otherwise specified. Here, it is assumed that the temperature of the battery cell 17 is continuously measured every predetermined time. Further, the upper limit value ΔT (+ limit), the lower limit value ΔT (−limit), and the upper limit number K ′ (+) of the temperature fluctuation amount are set in advance and stored in, for example, the nonvolatile memory 22 provided in the MPU 21.

  First, in step S21, based on the temperature T (n-1) at the time M '(n-1) and the temperature T (n) at the time M' (n) after a predetermined time has elapsed, the temperature variation ΔT (n ) Is calculated.

  In step S22, the temperature fluctuation amount ΔT (n) calculated in step S21 is compared with a preset upper limit value ΔT (+ limit) of the temperature fluctuation amount. As a result of the comparison, when the temperature fluctuation amount ΔT (n) is equal to or less than the upper limit value ΔT (+ limit), the process proceeds to step S23. In step S23, the upper limit value ΔT (+ limit) of the temperature fluctuation amount is returned to the initially stored value, and the value of the counter K ′ (+ cnt) is set to “0”.

  On the other hand, if it is determined in step S22 that the temperature fluctuation amount ΔT (n) is larger than the upper limit value ΔT (+ limit), the process proceeds to step S24. In step S24, the value of the counter K ′ (+ cnt) is incremented by “1”. Further, the temperature fluctuation amount ΔT (n) and the value of the counter K ′ (+ cnt) at this time are stored in the nonvolatile memory 22. If the temperature fluctuation amount ΔT (n) is already stored in the nonvolatile memory 22, the larger one of the two temperature fluctuation amounts ΔT (n) is stored.

  In step S25, the value of the counter K '(+ cnt) is compared with a preset upper limit number K' (+). As a result of the comparison, if the value of the counter K ′ (+ cnt) is smaller than the upper limit number K (+), it is determined that the battery pack 1 is normal, and the process proceeds to step S26. In step S26, an upper limit value ΔT (+ limit) of the temperature fluctuation amount is newly calculated based on the temperature fluctuation amount ΔT (n), and the process proceeds to step S27.

  On the other hand, if the value of the counter K ′ (+ cnt) is greater than or equal to the upper limit number K ′ (+) as a result of the comparison in step S25, it is determined that the battery pack 1 is abnormal, and the process proceeds to step S28. To do.

  In step S27, it is determined that the battery pack 1 is normal, normal processing is performed, the processing returns to step S1, and a series of processing is cyclically repeated every predetermined time.

  Further, in step S28, for example, an abnormal process is performed in which the charge / discharge control FET is turned off by the control of the AFE 20 to prohibit charging / discharging of the battery cell 17, and the series of processes ends.

  Next, the abnormality detection process of the battery pack 1 according to the embodiment of the present invention will be described with reference to a specific example. First, an upper limit value ΔV (+ limit), a lower limit value ΔV (−limit), a first upper limit number K (+), and a second upper limit number K (−) of the voltage fluctuation amount are set in advance and stored in the nonvolatile memory 22. Remember. In addition, here, when it is determined that there is an abnormality when the upper limit value ΔV (+ limit) is equal to or greater than the lower limit value ΔV (−limit) twice, that is, the first upper limit number K (+) and the second upper limit value are determined. A case where the number of times K (−) is “2” will be described as an example.

  As shown in FIG. 6A, the abnormality detection process when the voltage of the battery cell 17 is normal will be specifically described. Here, the case where the voltage of the battery cell 17 is normal and the case where the voltage is substantially constant will be described as an example.

The voltage of the battery cell 17 at the time points a and b is measured, and the voltage fluctuation amount ΔV ₁ is calculated based on the voltages at the time points a and b. Then, the calculated voltage fluctuation amount ΔV ₁ is compared with the upper limit value ΔV (+ limit). In this case, since the voltage fluctuation amount ΔV ₁ is substantially “0” and is smaller than the positive upper limit value ΔV (+ limit), the upper limit value ΔV (+ limit) is returned to a preset value. The first counter K (+ cnt) is cleared and the value is set to “0”.

Further, the voltage fluctuation amount ΔV ₁ is compared with the lower limit value ΔV (−limit). In this case, the voltage fluctuation amount ΔV ₁ is substantially “0” and is larger than the negative lower limit value ΔV (−limit), so the lower limit value ΔV (−limit) is set to a preset value. At the same time, the second counter K (-cnt) is cleared and the value is set to "0".

  Therefore, it is determined that the battery pack 1 is normal within the time from the time point a to the time point b, and normal processing is performed.

Next, the voltage of the battery cell 17 at the time point c is measured, and the voltage fluctuation amount ΔV ₂ is calculated based on the voltages at the time points b and c. Then, the calculated voltage fluctuation amount ΔV ₂ is compared with the upper limit value ΔV (+ limit). In this case, the voltage fluctuation amount ΔV ₂ is substantially “0”, which is smaller than the upper limit value ΔV (+ limit), which is a positive value, so that the value of the upper limit value ΔV (+ limit) is returned to a preset value. The first counter K (+ cnt) is cleared and the value is set to “0”.

Further, the voltage fluctuation amount ΔV ₂ is compared with the lower limit value ΔV (−limit). In this case, the voltage fluctuation amount ΔV ₂ is substantially “0” and is larger than the lower limit value ΔV (−limit), which is a negative value, so that the value of the lower limit value ΔV (−limit) is set to a preset value. At the same time, the second counter K (-cnt) is cleared and the value is set to "0".

  Therefore, within the time period from time point b to time point c, the battery pack 1 is determined to be normal and normal processing is performed.

  As described above, when the battery pack 1 is operating normally, the voltage of the battery cell 17 hardly fluctuates. Therefore, the voltage fluctuation amount ΔV is substantially “0”, and is equal to or less than the upper limit value ΔV (+ limit). Since the lower limit value ΔV (−limit) is exceeded, no abnormality is detected.

  Next, as shown in FIG. 6B, the abnormality detection process when noise is superimposed on the voltage of the battery cell 17 will be specifically described. Here, as an example in which noise is superimposed on the voltage of the battery cell 17, a case where the voltage instantaneously rises will be described.

The voltage of the battery cell 17 at the time points a ′ and b ′ is measured, and the voltage fluctuation amount ΔV ₁ ′ is calculated based on the voltages at the time points a ′ and b ′. Then, the calculated voltage fluctuation amount ΔV ₁ ′ is compared with the upper limit value ΔV (+ limit). In this case, since the voltage fluctuation amount ΔV ₁ ′ is larger than the upper limit value ΔV (+ limit), the value of the first counter K (+ cnt) is incremented by “1” and the value of the first counter K (+ cnt) is increased. “1” is set, and the voltage fluctuation amount ΔV ₁ ′ and the value of the first counter K (+ cnt) are stored in the nonvolatile memory 22.

Then, the first counter K (+ cnt) is compared with the first upper limit number K (+). In this case, since the value of the first counter K (+ cnt) is “1” and the value of the first upper limit number K (+) is “2”, the value of the first counter K (+ cnt) is Since it is smaller than the value of the first upper limit number K (+), an upper limit value ΔV (+ limit) is newly calculated based on the voltage fluctuation amount ΔV ₁ ′.

Next, the voltage fluctuation amount ΔV ₁ ′ is compared with the lower limit value ΔV (−limit). In this case, since the voltage fluctuation amount ΔV ₁ ′ is larger than the lower limit value ΔV (−limit), the value of the lower limit value ΔV (−limit) is returned to a preset value and the second counter K (− cnt) is cleared and the value is set to “0”.

  Therefore, it is determined that the battery pack 1 is normal within the time from the time point a ′ to the time point b, and normal processing is performed.

Next, the voltage of the battery cell 17 at the time point c ′ is measured, and the voltage fluctuation amount ΔV ₂ ′ is calculated based on the voltages at the time points b ′ and c ′. Then, the calculated voltage fluctuation amount ΔV ₂ ′ is compared with the upper limit value ΔV (+ limit). In this case, since the voltage fluctuation amount ΔV ₂ ′ is smaller than the upper limit value ΔV (+ limit), the value of the upper limit value ΔV (+ limit) is returned to a preset value, and the first counter K (+ cnt) is set. Clear and set the value to “0”.

Further, the voltage fluctuation amount ΔV ₂ ′ is compared with the lower limit value ΔV (−limit). In this case, since the voltage fluctuation amount ΔV ₂ ′ is smaller than the lower limit value ΔV (−limit), the value of the second counter K (−cnt) is incremented by “1” to increase the second counter K (−cnt). Is set to “1”, and the voltage fluctuation amount ΔV ₂ ′ and the value of the second counter K (−cnt) are stored in the nonvolatile memory 22.

Then, the second counter K (−cnt) is compared with the second upper limit number K (−). In this case, since the value of the second counter K (−cnt) is “1” and the value of the second upper limit number K (−) is “2”, the value of the second counter K (−cnt) Since the value is smaller than the value of the second upper limit number K (−), a new lower limit value ΔV (−limit) is calculated based on the voltage fluctuation amount ΔV ₂ ′.

  Therefore, it is determined that the battery pack 1 is normal within the time from the time point b 'to the time point c', and normal processing is performed.

Next, the voltage of the battery cell 17 at the time point d ′ is measured, and the voltage fluctuation amount ΔV ₃ ′ is calculated based on the voltages at the time points c ′ and d ′. Then, the calculated voltage fluctuation amount ΔV ₃ ′ is compared with the upper limit value ΔV (+ limit). In this case, since the voltage fluctuation amount ΔV ₃ ′ is smaller than the upper limit value ΔV (+ limit), the value of the upper limit value ΔV (+ limit) is returned to a preset value and the first counter K (+ cnt) is set. Clear and set the value to “0”.

Further, the voltage fluctuation amount ΔV ₃ ′ is compared with the lower limit value ΔV (−limit). In this case, since the voltage fluctuation amount ΔV ₃ ′ is larger than the lower limit value ΔV (−limit), the value of the lower limit value ΔV (−limit) is returned to a preset value and the second counter K (− cnt) is cleared and the value is set to “0”.

  Therefore, it is determined that the battery pack 1 is normal within the time from the time point c ′ to the time point d ′, and normal processing is performed.

  As described above, when noise is superimposed on the voltage of the battery cell 17, the voltage of the battery cell 17 fluctuates. However, since the voltage is instantaneous, the upper limit value ΔV (+ limit) is continuously exceeded or the lower limit value. It does not fall below ΔV (−limit). Therefore, an increase in voltage due to noise is not detected as an abnormality of the battery pack 1.

  Next, as shown in FIG. 6C, the abnormality detection process when the voltage of the battery cell 17 is abnormal will be specifically described. Here, as an example, the case where the voltage of the battery cell 17 continues to increase rapidly will be described as an example where the voltage of the battery cell 17 is abnormal.

The voltage of the battery cell 17 at the time point a ″ and the time point b ″ is measured, and a voltage fluctuation amount ΔV ₁ ″ is calculated based on the voltages at the time points a ″ and b ″. The calculated voltage fluctuation amount ΔV ₁ ″ The upper limit value ΔV (+ limit) is compared. In this case, since the voltage fluctuation amount ΔV ₁ ″ is larger than the upper limit value ΔV (+ limit), the value of the first counter K (+ cnt) is incremented by “1” and the value of the first counter K (+ cnt) is increased. “1” is set, and ΔV ₁ ″ and the value of the first counter K (+ cnt) are stored in the nonvolatile memory 22.

Then, the first counter K (+ cnt) is compared with the first upper limit number K (+). In this case, since the value of the first counter K (+ cnt) is “1” and the value of the first upper limit number K (+) is “2”, the value of the first counter K (+ cnt) is Since it is smaller than the value of the first upper limit number K (+), a new upper limit value ΔV (+ limit) is calculated based on the voltage fluctuation amount ΔV ₁ ″.

Further, the voltage fluctuation amount ΔV ₁ ″ is compared with the lower limit value ΔV (−limit). In this case, the voltage fluctuation amount ΔV ₁ ″ is larger than the lower limit value ΔV (−limit), and therefore the lower limit value ΔV (−limit). ) Is returned to a preset value, and the second counter K (−cnt) is cleared to set the value to “0”.

  Therefore, it is determined that the battery pack 1 is normal within the time from the time point a ″ to the time point b ″, and normal processing is performed.

Next, the voltage of the battery cell 17 at the time point c ″ is measured, and the voltage fluctuation amount ΔV ₂ ″ is calculated based on the voltages at the time points b ″ and the time point c ″. Then, the calculated voltage fluctuation amount ΔV ₂ ″ is compared with the upper limit value ΔV (+ limit). In this case, since the voltage fluctuation amount ΔV ₂ ″ is larger than the upper limit value ΔV (+ limit), the first counter K The value of (+ cnt) is incremented by “1”, the value of the first counter K (+ cnt) is set to “2”, and the value of the first counter K (+ cnt) is stored in the nonvolatile memory 22.

Further, the voltage fluctuation amount ΔV ₁ ″ stored in the nonvolatile memory 22 is compared with the calculated voltage fluctuation amount ΔV ₂ ″, and the larger fluctuation amount is stored in the nonvolatile memory 22. In this example, since the voltage fluctuation amount ΔV ₁ ″ has a larger fluctuation amount than the voltage fluctuation amount ΔV ₂ ″, the nonvolatile memory 22 remains in a state where ΔV ₁ ″ is stored.

  Next, the first counter K (+ cnt) is compared with the first upper limit number K (+). In this case, since the value of the first counter K (+ cnt) is “2” and the value of the first upper limit number K (+) is “2”, the value of the first counter K (+ cnt) is It becomes more than the value of the first upper limit number of times K (+). Accordingly, it is determined that an abnormality has occurred in the battery pack 1 within the time period from the time point b ″ to the time point c ″, and abnormality processing is performed.

  As described above, when the battery pack 1 is abnormal, the voltage of the battery cell 17 rapidly increases, so that the voltage increases or decreases continuously a predetermined number of times. Therefore, the abnormality of the battery pack 1 is detected based on the voltage increase degree.

  As described above, in the embodiment of the present invention, the upper limit value and the lower limit value of the fluctuation amount of the voltage and temperature, and the upper limit of the number of times exceeding the upper limit value and the lower limit value of the fluctuation amount are set in advance and within a predetermined time. The battery pack is judged to be abnormal depending on whether the fluctuation amount exceeds the upper limit value and the lower limit value a predetermined number of times or more. Therefore, a more accurate abnormality detection process can be performed, and erroneous detection of abnormality can be prevented.

  In addition, because the battery cell voltage and temperature fluctuation amount is calculated every predetermined time to detect an abnormality, it is possible to grasp the state of the battery pack and quickly detect the abnormality occurring in the battery pack. it can.

  Furthermore, by storing the maximum value of the fluctuation amount of the battery cell voltage and temperature and the number of times the upper and lower limits of the fluctuation amount are exceeded, for example, the failed battery pack is recovered and the cause of the failure is analyzed. In doing so, it can be confirmed how much the battery pack has changed.

  The embodiment of the present invention has been described above. However, the present invention is not limited to the embodiment of the present invention described above, and various modifications and applications can be made without departing from the gist of the present invention. Is possible. For example, the specific values of the upper limit value and the lower limit value of the voltage fluctuation amount, and the upper limit value of the temperature fluctuation amount are merely examples, and are not limited to this example, depending on the material and characteristics used for the battery cell 17. You may change suitably.

It is a basic diagram which shows the structure of an example of the battery pack by one Embodiment of this invention. It is a basic diagram which shows an example of the change of the voltage when abnormality arises in a battery pack. It is a basic diagram which shows an example of the change of the temperature when abnormality arises in a battery pack. It is a flowchart which shows an example of the process in the case of abnormality detection by the voltage of a battery cell. It is a flowchart which shows an example of the process in the case of abnormality detection by the temperature of a battery cell. It is a basic diagram which shows a specific example of the process of the abnormality detection with respect to the battery pack by one Embodiment of this invention.

Explanation of symbols

1 Battery pack 14 Switch circuit 15 Charge control FET
16 Discharge control FET
17 Battery cell 18 Temperature detection element 19 Current detection resistor 20 AFE
21 MPU
22 Nonvolatile memory

Claims (14)

One or more secondary batteries;
A measuring unit for measuring the voltage of the secondary battery every predetermined time;
A control unit that calculates a voltage fluctuation amount within a predetermined time based on the voltage, and controls charge / discharge of the secondary battery based on the voltage fluctuation amount;
A storage unit that stores a prescribed voltage fluctuation amount with respect to the voltage fluctuation amount, and an upper limit number indicating an upper limit of the number of times that the voltage fluctuation amount exceeds the prescribed voltage fluctuation amount;
The control unit
Compare the voltage fluctuation amount with the specified voltage fluctuation amount every predetermined time,
When the voltage fluctuation amount exceeds the specified voltage fluctuation amount, a counter value provided in advance in the storage unit is incremented, and when the counter value is equal to or more than the upper limit number, it is abnormal. A battery pack characterized by judging. The battery pack according to claim 1,
The specified voltage fluctuation amount is
A battery pack characterized by showing either an upper limit value or a lower limit value for the voltage fluctuation amount. The battery pack according to claim 2,
The control unit
A battery pack, wherein when the value of the counter is smaller than the upper limit count, a new upper limit value is calculated based on the voltage fluctuation amount, and the calculated upper limit value is updated. The battery pack according to claim 2,
The control unit
When the value of the counter is smaller than the upper limit number, a new lower limit value is calculated based on the voltage fluctuation amount, and the calculated lower limit value is updated. The battery pack according to claim 2,
The storage unit
A battery pack that stores a value of the counter and a maximum value of the voltage fluctuation amount when the voltage fluctuation amount becomes larger than the upper limit value. The battery pack according to claim 2,
The storage unit
A battery pack that stores a value of the counter and a minimum value of the voltage fluctuation amount when the voltage fluctuation amount is smaller than the lower limit value. The battery pack according to claim 2,
The control unit
A battery pack, wherein the upper limit value is returned to an initial value when the voltage fluctuation amount is equal to or less than the upper limit value. The battery pack according to claim 2,
The control unit
A battery pack, wherein the lower limit value is returned to an initial value when the voltage fluctuation amount is equal to or greater than the lower limit value. One or more secondary batteries;
A measuring unit for measuring the ambient temperature of the secondary battery every predetermined time;
Calculating a temperature fluctuation amount within a predetermined time based on the ambient temperature, and controlling a charge / discharge of the secondary battery based on the temperature fluctuation amount;
A storage unit for storing an upper limit value for the temperature fluctuation amount, and an upper limit count indicating the upper limit of the number of times that the temperature fluctuation amount is greater than the upper limit value;
The control unit
Compare the temperature fluctuation amount and the upper limit value at predetermined time intervals,
When the temperature fluctuation amount is larger than the upper limit value, the value of the counter provided in the storage unit is incremented, and when the counter value is equal to or more than the upper limit number, it is determined as abnormal. A battery pack characterized by that. The battery pack according to claim 9, wherein
The control unit
When the value of the counter is smaller than the upper limit number, a battery pack is newly calculated based on the temperature fluctuation amount, and the calculated upper limit value is updated. The battery pack according to claim 9, wherein
The storage unit
The battery pack, wherein the value of the counter and the maximum value of the temperature fluctuation amount are stored when the temperature fluctuation amount is larger than the upper limit value. The battery pack according to claim 9, wherein
The control unit
A battery pack, wherein the upper limit value is returned to an initial value when the temperature fluctuation amount is not more than the upper limit value. A measurement step of measuring the voltage of one or a plurality of secondary batteries every predetermined time;
Calculate the amount of voltage fluctuation within a predetermined time based on the above voltage,
Compare the voltage fluctuation amount for each predetermined time with the specified voltage fluctuation amount with respect to the voltage fluctuation amount stored in the storage unit,
When the voltage fluctuation amount exceeds the specified voltage fluctuation amount, the counter value provided in advance in the storage unit is incremented,
A control step for determining that the counter value is abnormal when the value of the counter is equal to or greater than an upper limit number indicating the upper limit of the number of times that the voltage fluctuation amount provided in advance in the storage unit exceeds the specified voltage fluctuation amount; A detection method comprising: A measurement step of measuring the ambient temperature of the one or more secondary batteries every predetermined time;
Calculate the amount of temperature fluctuation within a predetermined time based on the ambient temperature,
Comparing the temperature fluctuation amount for each predetermined time with the upper limit value for the temperature fluctuation amount stored in the storage unit,
If the temperature fluctuation amount is larger than the upper limit value, the counter value provided in advance in the storage unit is incremented,
A control step of determining that the counter value is abnormal when the temperature fluctuation amount provided in advance in the storage unit is equal to or greater than the upper limit number indicating the upper limit of the number of times greater than the upper limit value. A detection method characterized by the above.

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