Battery state detection device, battery recovery device, battery state detection method and battery recovery method

Abstract

To provide a battery state detection device that can more properly detecting the state of a secondary battery than the conventional one.SOLUTION: A battery state detection device 1 comprises: a reference waveform generation part 10 configuring a circuit including a secondary battery 100 for detecting the state of the secondary battery 100 to generate a reference waveform; an application waveform output part 20 outputting application waveform applied to the secondary battery 100 on the basis of the reference waveform and feedback-correcting a phase difference between the reference waveform and the application waveform; a detection part 30 detecting output signal waveform outputted from the secondary battery 100, with the application waveform being applied; and an index value acquisition part 41 acquiring, on the basis of detection result the detection part 30, an index value indicative of the amplitude of fluctuations generated in the output signal waveform.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery state detection device and a battery state detection method for detecting the state of a secondary battery, and a battery recovery device and a battery recovery method for recovering the battery capacity of a secondary battery. [Background technology]

[0002] Conventionally, in facilities that require continuous operation, such as data centers and public facilities (base stations), uninterruptible power supplies (UPS) equipped with secondary batteries (storage batteries) have been introduced as backup power sources in preparation for emergencies. Also, in vehicles such as automobiles, secondary batteries such as 12V lead batteries are used as power sources for driving control systems.

[0003] The condition of these secondary batteries changes with use. For example, secondary batteries gradually deteriorate with use, resulting in a decrease in charge capacity. If the secondary battery is a lead-acid battery, an increase in the number of charge / discharge cycles or leaving it in a partially charged state can cause lead sulfate to solidify on the surface of the lead electrodes, a phenomenon known as sulfation, which reduces the charge capacity of the secondary battery.

[0004] For this reason, the state of the secondary battery may be detected as necessary. Patent Document 1 describes that the degree of deterioration of a lead-acid battery or a lead battery module is estimated based on the internal resistance or conductance of the lead-acid battery (secondary battery). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-093253 Summary of the Invention [Problem to be solved by the invention]

[0006] The state of a secondary battery, such as the degree of deterioration, can be detected (estimated) based on the internal resistance or conductance of the secondary battery. However, the performance of secondary batteries varies among individual batteries, and the state of a secondary battery may change due to factors other than the internal resistance or conductance. Therefore, if the state of a secondary battery is detected based on the internal resistance or conductance, there is a risk that the state of the secondary battery cannot be detected appropriately.

[0007] Therefore, an object of the present disclosure is to provide a battery state detection device that can more appropriately detect the state of a secondary battery. [Means for solving the problem]

[0008] In order to solve the above problems, the present disclosure provides a battery state detection device that detects the state of a secondary battery, comprising: a reference waveform generation unit that generates a reference waveform; an applied waveform output unit that outputs an applied waveform to be applied to the secondary battery based on the reference waveform and feedback corrects the phase difference between the reference waveform and the applied waveform; a detection unit that detects an output signal waveform output from the secondary battery when the applied waveform is applied; and an index value acquisition unit that acquires an index value that indicates the magnitude of fluctuations occurring in the output signal waveform based on the detection result of the detection unit. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a battery state detection device that can more appropriately detect the state of a secondary battery. Note that problems, configurations, and effects other than those described above will become clear from the description of the following embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of the configuration of a battery state detection device according to an embodiment; [Figure 2] FIG. 10 is a diagram showing a modified example of an applied waveform output unit according to the embodiment. [Figure 3] 10A and 10B are diagrams illustrating an example of fluctuations in an output signal waveform. [Figure 4]10A and 10B are diagrams illustrating an example of fluctuations in an output signal waveform. [Figure 5] 4 is a flowchart illustrating an example of a battery state detection method according to an embodiment. [Figure 6] FIG. 4 is a diagram illustrating an example of information stored in a storage unit according to the embodiment. [Figure 7] FIG. 4 is a diagram illustrating an example of a screen displayed on a display unit according to the embodiment. [Figure 8] FIG. 10 is a diagram illustrating an example of an index value indicating the magnitude of fluctuation. [Figure 9] 4 is a flowchart illustrating an example of a battery state detection method according to an embodiment. [Figure 10] 10 is a graph showing changes in charging voltage in a secondary battery in an initial state and after operation. [Figure 11] FIG. 4 is a diagram illustrating an example of information stored in a storage unit according to the embodiment. [Figure 12] 4 is a flowchart illustrating an example of a battery state detection method according to an embodiment. [Figure 13] 10A and 10B are diagrams illustrating the rate of change in output impedance of a secondary battery in an initial state and after operation. [Figure 14] FIG. 4 is a diagram illustrating an example of information stored in a storage unit according to the embodiment. [Figure 15] 4 is a flowchart illustrating an example of a battery state detection method according to an embodiment. [Figure 16] 10A and 10B are diagrams showing the chargeable energy amounts of a secondary battery in an initial state and after operation. [Figure 17] FIG. 4 is a diagram illustrating an example of information stored in a storage unit according to the embodiment. [Figure 18] 1 is a diagram illustrating an example of the configuration of a battery state detection device according to an embodiment; [Figure 19] 1 is a flowchart illustrating an example of a battery recovery method according to an embodiment. [Figure 20] FIG. 10 is a diagram showing changes in the charging voltage of the secondary battery before and after the execution of the recovery process. [Figure 21] FIG. 4 is a diagram illustrating an example of information stored in a storage unit according to the embodiment. [Figure 22] FIG. 10 is a diagram showing changes in charging voltage in a secondary battery before and after execution of a recovery process. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In all drawings for explaining the embodiments, components having the same functions are designated by the same reference numerals, and repeated explanations thereof will be omitted. In addition, in the explanation of the embodiments, explanations of identical or similar parts will not be repeated in principle unless particularly necessary.

[0012] (Summary of the technology disclosed herein) The battery state detection device of the present disclosure is a device that detects the state (degree of deterioration) of a secondary battery. The battery recovery device of the present disclosure is a device that includes the battery state detection device and performs recovery processing of the secondary battery, which is a lead-acid battery, as needed based on the detection result of the battery state detection device.

[0013] The characteristics of a secondary battery (storage battery) vary depending on the state of the secondary battery. For example, the output impedance of a secondary battery increases as the secondary battery deteriorates, and the output impedance tends to become unstable. For example, if the secondary battery is a lead-acid battery, so-called sulfation occurs, which increases the output impedance and tends to make the output impedance unstable. If the output impedance becomes unstable, fluctuations occur in the output signal waveform (voltage waveform, current waveform) that is output when a predetermined waveform is applied to the secondary battery.

[0014] Therefore, the battery state detection device of the present disclosure acquires an index indicating the magnitude of the fluctuation (sometimes called a fluctuation component) occurring in the output signal waveform, and detects the state of the secondary battery from the acquired index value. This allows the state of the secondary battery to be detected more appropriately. Furthermore, the battery recovery device of the present disclosure performs a recovery process for the secondary battery based on the detection result of the battery state detection device, thereby enabling the secondary battery to be recovered efficiently at an appropriate timing. Below, an example of the configuration of the battery state detection device and the battery recovery process according to the embodiment will be described.

[0015] (Embodiment 1) <General configuration of battery state detection device> Fig. 1 is a diagram showing an example of the overall configuration of a battery state detection device of embodiment 1. As shown in Fig. 1, the battery state detection device 1 of embodiment 1 is electrically connected to a secondary battery 100 to detect the state of the secondary battery 100, and has a circuit including the secondary battery 100. The battery state detection device 1 includes, as main components, a reference waveform generation unit 10, an applied waveform output unit 20, a detection unit 30, a calculation unit 40, a display unit 50, and a storage unit 60, of which the reference waveform generation unit 10, the applied waveform output unit 20, and the detection unit 30 constitute a circuit including the secondary battery 100.

[0016] The secondary battery 100, the object of status detection, is used, for example, as an uninterruptible power supply (UPS) or the like, and is, for example, removed from the uninterruptible power supply and connected to the battery status detection device 1. The secondary battery 100 may be incorporated into the uninterruptible power supply or the like. As long as the voltage range of the battery status detection device 1 is appropriate, the status of the secondary battery 100 can be detected even when incorporated into the uninterruptible power supply. In this example, the secondary battery 100 is a lead-acid battery and is composed of multiple battery cells 101 connected in series. This secondary battery 100 can also be referred to as a battery module including multiple battery cells 101. The configuration and use of the secondary battery 100 are not particularly limited. The secondary battery 100 does not have to be composed of multiple battery cells 101, but may be composed of a single battery cell 101. The secondary battery 100 may also be, for example, a 12V lead-acid battery installed in an automobile or the like.

[0017] Reference waveform generating unit (reference waveform generating circuit) 10 includes an oscillator 11 and generates a reference waveform (reference signal) whose voltage level fluctuates repeatedly at a constant cycle. In this example, reference waveform generating unit 10 generates a reference waveform (voltage waveform) that is a so-called rectangular wave (also called a square wave). The configuration of reference waveform generating unit 10 including oscillator 11 is not particularly limited, and an existing configuration such as a general-purpose timer IC may be adopted, for example. Furthermore, the reference waveform does not necessarily have to be a rectangular wave; for example, it can be a sine wave.

[0018] The applied waveform output unit (applied waveform output circuit) 20 outputs an applied waveform to be applied to the secondary battery 100 from the reference waveform generated by the reference waveform generation unit 10. The applied waveform output unit 20 includes, for example, a voltage-controlled oscillator (VCO) 21, an amplifier 22, and a correction circuit 23. The voltage-controlled oscillator 21 is an oscillation circuit (oscillator) that controls the oscillation frequency using voltage. Based on the reference waveform Vin generated by the reference waveform generation unit 10, the voltage-controlled oscillator 21 generates an applied waveform having a frequency corresponding to the reference waveform Vin. The generated applied waveform Vout is appropriately amplified by the amplifier 22 and applied to the secondary battery 100. Note that the amplifier 22 may be provided as needed and is not an essential component. If a phase difference (phase shift) occurs between the reference waveform Vin and the applied waveform Vout, the correction circuit 23 performs feedback correction on the applied waveform Vout to eliminate this phase difference. In other words, the correction circuit 23 performs feedback correction so that the phase of the applied waveform Vout coincides with that of the reference waveform Vin. The configurations of the voltage controlled oscillator (VCO) 21, amplifier 22, and correction circuit 23 included in the applied waveform output section 20 are not particularly limited, and existing configurations may be adopted.

[0019] Furthermore, the applied waveform output section 20 is not limited to the above configuration as long as it outputs the applied waveform Vout to be applied to the secondary battery 100 based on the reference waveform Vin generated by the reference waveform generation section 10 and performs feedback correction of the phase difference between the reference waveform Vin and the applied waveform Vout. For example, as shown in Fig. 2, the applied waveform output section 20 may be configured to include a so-called phase-locked loop (PLL) circuit having a voltage-controlled oscillator 21, a phase comparator 24 and a loop filter 25 provided in the preceding stage of the voltage-controlled oscillator 21, and a frequency divider 26 provided in the subsequent stage of the voltage-controlled oscillator 21. Note that the phase comparator 24, the loop filter 25, and the frequency divider 26 are also conventional components, and therefore their description will be omitted.

[0020] The detection unit (detection circuit) 30 detects the output signal waveform output from the secondary battery 100 when the application waveform Vout is applied. The detection unit 30 detects the waveform of the output voltage (output voltage waveform) or the waveform of the output current (output current waveform) output from the secondary battery 100 as the output signal waveform. As an example, the detection unit 30 is configured to include a resistor 31 connected in a stage subsequent to the secondary battery 100 and a voltmeter (voltage detector) 32 that measures the voltage between the terminals of the resistor 31, and detects the output voltage waveform as the output signal waveform of the secondary battery 100.

[0021] The detection unit 30 detects the voltage between the terminals of the resistor 31, but it can also be said that it converts the output current of the secondary battery 100 into an output voltage and detects it. In other words, it can also be said that the detection unit 30 essentially detects the output current of the secondary battery 100. The detection unit 30 may also be provided with an ammeter such as a clamp ammeter, and may detect the output current of the secondary battery 100 using the ammeter.

[0022] The calculation unit 40 is configured with, for example, a CPU (Central Processing Unit), memory, etc., and comprehensively controls the battery state detection device 1, and can also be called a control device. As will be described in detail later, the calculation unit 40 acquires, for example, an index value indicating the magnitude of fluctuation occurring in the output signal waveform of the secondary battery 100 based on the detection result of the detection unit 30. Furthermore, in this example, the calculation unit 40 determines the state of the secondary battery 100 based on the magnitude of the acquired index value. Note that the calculation unit 40 may be connected to the detection unit 30 by wire or wireless communication. Furthermore, the calculation unit 40 does not necessarily have to be an on-premise type and may be realized, for example, by a virtual server constructed on a cloud computing service.

[0023] A display unit (display device) 50 serving as a user interface, which is configured, for example, by a display, is connected to the calculation unit 40. The display unit 50 displays information such as the detection results by the detection unit 30 and the determination results of the state of the secondary battery 100 by the calculation unit 40. Furthermore, a storage unit 60 is connected to the calculation unit 40, which stores the detection results by the detection unit 30 and various information used to determine the state of the secondary battery 100. The storage unit (storage device) 60 is configured to include, for example, a flash memory or a hard disk.

[0024] Next, the calculation unit 40 will be described in more detail. The calculation unit 40 has an index value acquisition unit 41, a state determination unit 42, and a display control unit 43. The index value acquisition unit 41 acquires an index value indicating the magnitude of fluctuation occurring in the output signal waveform from the detection result of the detection unit 30, in this example, the detection result of the output signal waveform (output voltage waveform) of the secondary battery 100.

[0025] When a rectangular waveform is applied to the secondary battery 100, the output signal waveform (output voltage waveform) detected by the detection unit 30 corresponds to the applied waveform. However, when feedback correction of the applied waveform is performed by the applied waveform output unit 20, that is, when a phase difference occurs between the applied waveform and the reference waveform, a "fluctuation" occurs after the falling edge of the output signal waveform. This fluctuation occurs when there is a phase difference between the applied waveform and the reference waveform. This fluctuation can also be considered a jitter component that occurs in the output signal waveform due to the phase difference between the applied waveform and the reference waveform.

[0026] As described above, when secondary battery 100 is a lead-acid battery, increased sulfation easily causes the output impedance to become unstable, resulting in a phase difference between the applied waveform and the reference waveform. If the phase difference between the applied waveform and the reference waveform is small (if the output impedance is stable), feedback correction will essentially eliminate the phase difference, thereby suppressing fluctuations. On the other hand, if the phase difference between the applied waveform and the reference waveform becomes large (if the output impedance becomes more unstable), feedback correction will not be able to fully eliminate the phase difference, resulting in fluctuations in the output signal waveform.

[0027] 3 and 4 are diagrams illustrating an example of fluctuations occurring in the output signal waveform, where FIG. 3 is a diagram showing an example of fluctuations when the output impedance is stable, and FIG. 4 is a diagram showing an example of fluctuations when the output impedance is unstable.

[0028] As shown in FIGS. 3 and 4, a fluctuation 200, which can be considered a jitter component of the output signal waveform, is a fluctuation in the output voltage that occurs immediately after the falling edge of the output signal waveform. The amount of fluctuation in the output voltage is greatest immediately after the occurrence of the fluctuation 200 and then gradually decreases and converges. The magnitude of the fluctuation 200 varies depending on the state (which can also be considered a degradation state) of the secondary battery 100. When the phase difference between the applied waveform and the reference waveform is small and the output impedance state of the secondary battery 100 is stable, as shown in FIG. 3, the magnitude of the fluctuation 200 (e.g., peak-to-peak value ΔV) occurring in the output signal waveform is relatively small. Furthermore, the period ΔT during which the fluctuation 200 occurs is also relatively short. On the other hand, when the phase difference between the applied waveform and the reference waveform becomes large and the output impedance state of the secondary battery 100 becomes unstable, the magnitude of the fluctuation 200 (peak-to-peak value ΔV) increases, as shown in FIG. 4. Furthermore, the period ΔT during which the fluctuation 200 occurs also increases. There is a correlation between the magnitude of the fluctuation 200 and the period during which the fluctuation 200 occurs, and the larger the magnitude of the fluctuation 200, the longer the period ΔT during which the fluctuation 200 occurs tends to be.

[0029] Therefore, the index value acquiring unit 41 acquires the peak value of the fluctuation 200 (for example, peak-to-peak value ΔV) or the period ΔT during which the fluctuation 200 occurs as an index value indicating the magnitude of the fluctuation 200 occurring in the output signal waveform from the detection result of the output signal waveform of the secondary battery 100 by the detection unit 30. In other words, the index value acquiring unit 41 identifies the peak-to-peak value ΔV or the period ΔT of the output signal waveform of the secondary battery 100 from the detection result of the detection unit 30 by calculation or the like. In this example, the index value acquiring unit 41 acquires the peak-to-peak value ΔV of the fluctuation 200 as an index value indicating the magnitude of the fluctuation 200. Of course, the index value acquiring unit 41 may also acquire the period ΔT during which the fluctuation 200 occurs as the index value of the fluctuation 200.

[0030] The fluctuation 200 occurring in the output signal waveform changes depending on the instability of the output impedance as described above. Therefore, the index value indicating the magnitude of the fluctuation 200 can also be said to be an index value indicating the instability of the output impedance of the secondary battery 100.

[0031] The state determination unit 42 determines the state of the secondary battery 100 based on the magnitude of the index value indicating the scale of the fluctuation 200 thus acquired by the index value acquisition unit 41. As will be described in detail later, the state determination unit 42 of this embodiment determines the state of the secondary battery 100 based on the magnitude of the fluctuation 200 acquired by the index value acquisition unit 41 (in this example, the peak-to-peak value ΔV). The state determination unit 42 determines whether the state of the secondary battery 100 is, for example, a normal state, a deteriorated state, or an abnormal state. The determination result of the secondary battery 100 by the state determination unit 42 is stored in the storage unit 60.

[0032] The display control unit 43 controls the display unit 50 to display necessary information for the user on the display unit 50. As an example, when the state of the secondary battery 100 is determined by the state determination unit 42, the display control unit 43 causes the display unit 50 to display the determination result for the user.

[0033] The battery state detection device 1 configured as above can appropriately detect the state (degree of deterioration) of the secondary battery 100. An example of a battery state detection method using the battery state detection device 1 will now be described.

[0034] <Explanation of battery status detection method> FIG. 5 is a flowchart showing an example of a battery state detection method using a battery state detection device. As shown in FIG. 5, with a secondary battery 100 to be detected connected to the battery state detection device 1, an application waveform is first applied to the secondary battery 100 in step S01. Specifically, as described above, the reference waveform generation unit 10 generates the reference waveform Vin, and the application waveform output unit 20 outputs the application waveform Vout based on the generated reference waveform Vin. At this time, the application waveform output unit 20 performs feedback correction so as to eliminate the phase difference between the reference waveform Vin and the application waveform Vout. Note that application of the application waveform to the secondary battery 100 is initiated, for example, in response to a user instruction input via an input device (not shown).

[0035] With the applied waveform Vout being feedback corrected in this manner, the output signal waveform (voltage waveform) output from the secondary battery 100 is detected (step S02). In other words, the output signal waveform (voltage waveform) feedback corrected by the correction circuit 23 of the applied waveform output unit 20 is obtained. In this example, the output signal waveform is obtained by detecting the voltage between the terminals of the resistor 31 using the voltmeter 32 in the detection unit 30 (detection step).

[0036] Next, the state of the secondary battery 100 is determined based on the acquired output signal waveform (determination step). More specifically, the state of the secondary battery 100 is determined depending on whether or not fluctuations 200 can be confirmed in the acquired output signal waveform. First, in step S03, the index value acquisition unit 41 acquires an index value indicating the magnitude of the fluctuations 200 occurring in the output signal waveform of the secondary battery 100 based on the detection result by the detection unit 30 (acquisition step). The index value acquisition unit 41 acquires, as an example of the index value, the peak value of the fluctuations 200 in the output signal waveform, in this example, the peak-to-peak value ΔV.

[0037] Next, the state determination unit 42 determines whether or not the fluctuation 200 occurring in the output signal waveform can be confirmed (step S04). More specifically, the state determination unit 42 determines whether or not the peak-to-peak value ΔV of the fluctuation 200 acquired by the index value acquisition unit 41 is equal to or greater than a preset first threshold ΔV th1 It is determined whether the peak-to-peak value ΔV is equal to or greater than the first threshold value ΔV th1 If the peak-to-peak value ΔV is smaller than the first threshold value ΔV (step S04: No), the state determination unit 42 determines that the fluctuation 200 cannot be confirmed in the secondary battery 100, that is, the secondary battery 100 is in a normal state (step S05). th1 If so (step S04: Yes), the state determination unit 42 determines that fluctuation 200 can be confirmed in the secondary battery 100, that is, the secondary battery 100 is in an abnormal state (step S06).

[0038] Here, the secondary battery 100 is a lead storage battery, and the fluctuation 200 of the output signal waveform tends to increase with an increase in sulfation. For this reason, the state determination unit 42 determines whether the peak-to-peak value ΔV, which is the index value, is greater than the first threshold ΔV th1 If the above condition is met, the secondary battery 100 is determined to be in an abnormal state due to sulfation.

[0039] The abnormal state refers to a state other than the normal state, and in this example, includes a degraded state and an abnormal state. In the embodiment, the degraded state is a state in which degradation of the secondary battery 100 is recognized, but recovery processing of the secondary battery 100 is not required at this stage. The abnormal state is a state in which excessive degradation of the secondary battery 100 is recognized, and recovery processing of the secondary battery 100 is required. The abnormal state may also include states other than the degraded state and the abnormal state. In other words, multiple classifications with different degrees of degradation may be set for the abnormal state. Furthermore, multiple classifications may be set for the degraded state and the abnormal state.

[0040] When the state determination unit 42 determines that the secondary battery 100 is in an abnormal state (step S06), it further determines to which of the multiple classifications the abnormal state of the secondary battery 100 corresponds. As an example, the state determination unit 42 determines whether the peak-to-peak value ΔV as an index value is a predetermined second threshold ΔV th2 (>ΔV th1 It is determined whether the peak-to-peak value ΔV is equal to or greater than the second threshold value ΔV (step S07). th2 If the peak-to-peak value ΔV is smaller than the second threshold value ΔV (step S07: No), the state determination unit 42 determines that the state of the secondary battery 100 is in a deteriorated state corresponding to one of the above categories (step S08). th2 If the number is equal to or greater than this (step S07: Yes), the state determination unit 42 determines that the state of the secondary battery 100 is an abnormal state corresponding to one of the categories (step S09).

[0041] Here, the threshold value of the index value (in this example, the first threshold ΔV th1 and the second threshold ΔV th2 ) is set individually depending on the type of the secondary battery 100. As shown in an example in FIG. 6, the first threshold ΔV th1 and the second threshold ΔV th2 is stored in the storage unit 60 for each type of secondary battery 100. When performing state determination, the state determination unit 42 uses the first threshold value ΔV th1 and the second threshold ΔV th2 from the storage unit 60 and determines the state of the secondary battery 100 as described above. Note that information about the secondary battery 100 to be detected, such as its type, is registered in the battery state detection device 1 by, for example, a user and stored in the storage unit 60 before detecting the state of the secondary battery 100.

[0042] After the state determination unit 42 has completed determining the state of the secondary battery 100, in step S010, the determination result (detection result) of the state of the secondary battery 100 is displayed on the display unit 50. In this example, the display control unit 43 acquires the determination result by the state determination unit 42 and causes the display unit 50 to display it.

[0043] Fig. 7 is a diagram showing an example of a screen showing the detection result of the state of the secondary battery 100 displayed on the display unit 50. When the detection of the state of the secondary battery 100 is completed, the determination result of the state of the secondary battery 100 is displayed on the display unit 50 together with information about the secondary battery 100 such as the battery cell name, as shown in the example of Fig. 7. Specifically, the battery state determination result displays whether the state of the secondary battery 100 is normal, degraded, or abnormal. The screen shown in Fig. 7 is an example of a case where the state of the secondary battery 100 is determined to be degraded.

[0044] It is preferable that the display unit 50 displays, together with the battery state determination result, the waveform of the fluctuation 200 partially extracted from the output signal waveform and index values ​​(peak-to-peak value ΔV, occurrence period ΔT, etc.) obtained from the waveform of the fluctuation 200. Furthermore, the display unit 50 may also display, together with the battery state determination result, whether recovery work (recovery processing) for the secondary battery 100 is necessary and the period required for the recovery work, etc. This makes it easier for the user to visually recognize the battery state.

[0045] As described above, the battery state detection device 1 of this embodiment is configured to acquire an index value indicating the magnitude of the fluctuation 200 from the output signal waveform while the waveform is being applied to the secondary battery 100. Then, by determining the state of the secondary battery 100 based on this index value, the state of the secondary battery 100, for example, the degree of deterioration, can be appropriately detected.

[0046] In this example, the calculation unit 40 (state determination unit 42) included in the battery state detection device 1 determines the state of the secondary battery 100 based on the index value, but the state determination of the secondary battery 100 does not necessarily have to be performed by the battery state detection device 1. The state determination of the secondary battery 100 may be performed by another device based on the index value detected by the battery state detection device 1, or may be performed by the user himself.

[0047] In this embodiment, an example has been described in which the index value acquiring unit 41 acquires the peak-to-peak value ΔV of the fluctuation 200 or the occurrence period ΔT of the fluctuation 200 as an index value indicating the magnitude of the fluctuation 200, but the index value is not limited to these. For example, as shown in Fig. 8, the index value acquiring unit 41 may acquire the positive side peak value (maximum amplitude) V1 and the negative side peak value (maximum amplitude) V1' of the fluctuation 200 as index values ​​indicating the magnitude of the fluctuation 200. In this case, the positive side threshold V1 corresponding to the positive side peak value V1 is th+ and the negative threshold V corresponding to the negative peak value V1' th- and are stored in the storage unit 60. The state determination unit 42 determines whether the positive side peak value V1 is greater than or equal to the positive side peak value V1 th+ Whether the minus side peak value V1' is equal to or greater than the minus side peak value V1 th- The state of the secondary battery 100 can be determined based on whether or not it is equal to or less than this. Furthermore, the index value may be anything that can identify the magnitude of the fluctuation 200, and may be, for example, the curvature of a so-called signal envelope in the fluctuation 200.

[0048] (Embodiment 2) 9 is a flowchart showing an example of a battery state detection method according to embodiment 2. Note that embodiment 2 is a modification of step S07 in the battery state detection method according to embodiment 1, and the other steps are the same as those in embodiment 1, so detailed description thereof will be omitted.

[0049] In embodiment 1, when the state determination unit 42 determines that the state of the secondary battery 100 is abnormal (step S06), then in step S07, the state of the secondary battery 100 is further determined based on the magnitude of the index value indicating the scale of the fluctuation 200.

[0050] In contrast, in the second embodiment, as shown in FIG. 9 , when the state determination unit 42 determines that the state of the secondary battery 100 is abnormal (step S06), then in step S071, the state of the secondary battery 100 is further determined based on a criterion different from the index value indicating the magnitude of the fluctuation 200. In step S071, the state determination unit 42 determines the state of the secondary battery 100 based on a change in the battery voltage (hereinafter referred to as the charging voltage) when the secondary battery 100 is being charged. More specifically, the state determination unit 42 determines the state of the secondary battery 100 based on the difference (hereinafter referred to as the change amount difference) VD between the amount of change in the charging voltage of the secondary battery 100 in the initial state and the amount of change in the charging voltage of the secondary battery 100 after operation (after use). As an example, the state determination unit 42 determines the state of the secondary battery 100 based on the difference VD between the amount of change in the charging voltage of the secondary battery 100 in the initial state and the amount of change in the charging voltage of the secondary battery 100 after operation (after use). th The state of the secondary battery 100 is determined based on whether the change amount difference VD is equal to or greater than the difference threshold VD th If the change amount difference VD is smaller than the difference threshold VD (step S071: No), the state determination unit 42 determines that the state of the secondary battery 100 is the above-described deteriorated state (step S08). th If so (step S071: Yes), the state determining unit 42 determines that the secondary battery 100 is in the abnormal state (step S09).

[0051] Here, for the multiple secondary batteries E1 to E3, the charging voltage V BAT The results of investigating the change in charge voltage V are explained below. Fig. 10 is a graph showing the change in charge voltage V for secondary batteries E1 to E3 in the initial state and after operation. The graph in Fig. 10 shows the charge voltage V when constant current / constant voltage charging (CCCV) is performed for a predetermined time T1 (several seconds to several tens of minutes) for secondary batteries E1 to E3 in the initial state and secondary batteries E1 to E3 after operation. BAT The figure shows the change in the charging voltage V before charging each of the secondary batteries E1 to E3. BAT is set to be about the same (around 2.6[v]).

[0052] When the secondary batteries E1 to E3 are initially charged, the charging voltage V of each secondary battery E1 to E3 is as shown by the solid line in the figure.BAT increases to a set voltage (for example, around 2.9 [v]), and the charging voltage V of each secondary battery E1 to E3 BAT On the other hand, when the secondary batteries E1 to E3 after operation were charged under the same conditions, the charge voltage V of each of the secondary batteries E1 to E3 increased, as shown by the dotted lines in the figure. BAT For all of the secondary batteries E1 to E3, the charging voltage V after charging for a predetermined time T1 was lower than the initial voltage, compared to the initial state. BAT In other words, the amount of change in the charging voltage V after charging for the predetermined time T1 was significantly different between the secondary batteries E1 to E3 in the initial state and the secondary batteries E1 to E3 after operation. BAT were significantly different.

[0053] In addition, for the secondary batteries E1 to E3 after operation, the charging voltage V BAT In other words, the change in the charging voltage V of the secondary batteries E1 to E3 after operation BAT The amount of change in the secondary batteries E1 to E3 decreases as the deterioration of the secondary batteries E1 to E3 progresses. Accordingly, the amount of change difference VD (VD1 to VD3) of each of the secondary batteries E1 to E3 increases as the deterioration of the secondary batteries E1 to E3 progresses.

[0054] In the example shown in Fig. 10, the change amount difference VD1 of the secondary battery E1 is the largest, and the change amount difference VD3 of the secondary battery E3 is the smallest. Furthermore, when the states of the secondary batteries E2 and E3 after operation are determined based on the index value indicating the magnitude of fluctuation, it is confirmed that the state of the secondary battery E2 is in the above-mentioned degraded state, and the state of the secondary battery E3 is in an abnormal state. From these facts, it can be said that the change amount difference VD of the secondary batteries becomes smaller as the degradation of the secondary batteries progresses.

[0055] Therefore, in step S071, the state determination unit 42 can appropriately determine the state of the secondary battery 100 based on the change amount difference VD of the secondary battery 100. Furthermore, since the change amount VD of the secondary battery 100 can be acquired in a relatively short time, the time required to determine the state of the secondary battery 100 can be shortened. Furthermore, in the battery state detection method according to the second embodiment, the determination based on the index value indicating the magnitude of the fluctuation 200 (step S04) and the charging voltage V of the secondary battery 100 are performed. BAT In this example, the state (degree of deterioration) of the secondary battery 100 is determined in combination with a determination based on a change in the amount of change difference VD (step S071). This makes it possible to determine the state of the secondary battery 100 more appropriately.

[0056] As shown in an example in FIG. 11, the charging voltage of the secondary battery 100 to be detected in the initial state and after operation, and the difference threshold VD that is the criterion for determining the change amount difference VD are th Such information is stored in the storage unit 60 for each type of secondary battery 100. When performing state determination, the state determination unit 42 reads out the necessary information from the storage unit 60 and determines the state of the secondary battery 100 as described above.

[0057] In this embodiment, the state of the secondary battery 100 is determined based on the change amount difference VD of the secondary battery 100. However, for example, the charge voltage V BAT The state of the secondary battery 100 can also be determined based on the amount of change (amount of change before and after charging).

[0058] (Embodiment 3) 12 is a flowchart showing an example of a battery state detection method according to embodiment 3. Note that embodiment 3 is a modification of step S07 in the battery state detection method according to embodiment 1, and the other steps are the same as those in embodiment 1, so detailed description thereof will be omitted.

[0059] In embodiment 1, when the state determination unit 42 determines that the state of the secondary battery 100 is abnormal (step S06), then in step S07, the state of the secondary battery 100 is further determined based on the magnitude of the index value indicating the scale of the fluctuation 200.

[0060] In contrast, in the third embodiment, as shown in Fig. 12, when the state determination unit 42 determines that the state of the secondary battery 100 is abnormal (step S06), then in step S072, the state of the secondary battery 100 is further determined based on a criterion different from the index value indicating the magnitude of the fluctuation 200. In step S072, the state determination unit 42 determines the state of the secondary battery 100 based on a rate of change (referred to as an impedance change rate) Ra1 of the output impedance of the secondary battery 100 with respect to its initial value. More specifically, the state determination unit 42 determines the state of the secondary battery 100 based on the impedance change rate Ra1 being equal to or lower than a preset impedance threshold value Ra1. th The state of the secondary battery 100 is determined based on whether the impedance change rate Ra1 is equal to or greater than the impedance threshold Ra1. th If the impedance change rate Ra1 is smaller than the impedance threshold Ra1 (step S072: No), the state determination unit 42 determines that the secondary battery 100 is in the deteriorated state (step S08). th If so (step S072: Yes), the state determining unit 42 determines that the state of the secondary battery 100 is the abnormal state (step S09).

[0061] FIG. 13 is a diagram showing an example of the rate of change in output impedance of a secondary battery in the initial state and after operation. The impedance change rate Ra1, which is the rate of change in output impedance of a secondary battery in the initial state and after operation, varies depending on the performance and usage conditions of the secondary battery, such as the operation period. The impedance change rate Ra1 of each secondary battery (battery numbers A to F) shown in FIG. 13 is a different value. For example, in the case of battery number A, the impedance change rate Ra1 is about 1.3. In other words, the result for battery number A shows that the output impedance after operation increased to about 1.3 times the output impedance in the initial state.

[0062] Then, when the post-operation state (degree of deterioration) of each secondary battery with battery numbers A to F was determined based on the index value indicating the magnitude of fluctuation, it was confirmed that the states of battery numbers A and B corresponded to the above-mentioned deteriorated state, the states of battery numbers C and D corresponded to an abnormal state, and the states of battery numbers E and F corresponded to the above-mentioned normal state. From this, it can be said that the impedance change rate Ra1 of a secondary battery increases as the deterioration of the secondary battery progresses.

[0063] Therefore, in step S071, the state determination unit 42 can appropriately determine the state of the secondary battery 100 based on the rate of change in impedance Ra1 of the secondary battery 100. Furthermore, in the battery state detection method according to the third embodiment, the state (degree of deterioration) of the secondary battery 100 is determined by combining the determination based on the index value indicating the magnitude of the fluctuation 200 (step S04) and the determination based on the rate of change in impedance Ra1 of the secondary battery 100 (step S071). This allows the state of the secondary battery 100 to be determined more appropriately.

[0064] As shown in an example in FIG. 14, the output impedance of the secondary battery 100 to be detected in the initial state and after operation, and the impedance threshold Ra1 that is the criterion for the impedance change rate Ra1 are th Such information is stored in the storage unit 60 for each type of secondary battery 100. When performing state determination, the state determination unit 42 reads out the necessary information from the storage unit 60 and determines the state of the secondary battery 100 as described above.

[0065] (Embodiment 4) 15 is a flowchart showing an example of a battery state detection method according to embodiment 4. Note that embodiment 4 is a modification of step S07 in the battery state detection method according to embodiment 1, and the other steps are the same as those in embodiment 1, so detailed description thereof will be omitted.

[0066] In embodiment 1, when the state determination unit 42 determines that the state of the secondary battery 100 is abnormal (step S06), then in step S07, the state of the secondary battery 100 is further determined based on the magnitude of the index value indicating the scale of the fluctuation 200.

[0067] In contrast, in the fourth embodiment, as shown in FIG. 15, when the state determination unit 42 determines that the state of the secondary battery 100 is abnormal (step S06), then in step S073, the state of the secondary battery 100 is further determined based on a criterion different from the index value indicating the magnitude of the fluctuation 200. In step S073, the state determination unit 42 determines the state of the secondary battery 100 based on a change in the amount of chargeable energy of the secondary battery 100 from its initial value. In this example, the state determination unit 42 determines the state of the secondary battery 100 based on a rate of change (hereinafter referred to as the energy change rate) Ra2 from its initial value of the amount of chargeable energy. More specifically, the state determination unit 42 determines the state of the secondary battery 100 based on the rate of change R2 in the amount of chargeable energy from its initial value. th The state of the secondary battery 100 is determined based on whether the power amount change rate Ra2 is equal to or greater than the power amount threshold Ra2. th If the power amount change rate Ra2 is smaller than the power amount threshold Ra2 (step S073: No), the state determination unit 42 determines that the secondary battery 100 is in the degraded state (step S08). th If so (step S073: Yes), the state determining unit 42 determines that the state of the secondary battery 100 is the abnormal state (step S09).

[0068] Fig. 16 is a diagram showing an example of the chargeable energy of a secondary battery in an initial state and after operation. The chargeable energy of secondary battery 100 varies depending on the performance and usage conditions of the secondary battery, such as the period of operation. As shown in an example in Fig. 16, the chargeable energy (also called charging capacity) of each secondary battery (battery numbers A to F) after operation is significantly reduced from the initial state, although there is some variation.

[0069] Then, when the post-operation state of each secondary battery with battery numbers A to F was determined based on the index value indicating the magnitude of fluctuation, it was confirmed that the states of battery numbers A and B corresponded to the above-mentioned degraded state, the states of battery numbers C and D corresponded to an abnormal state, and the states of battery numbers E and F corresponded to the above-mentioned normal state. From this, it can be said that the amount of change (decrease) in the chargeable energy of a secondary battery increases as the degradation of the secondary battery progresses.

[0070] Therefore, in step S073, the state determination unit 42 can appropriately determine the state of the secondary battery 100 based on the rate of change in the amount of electric power Ra2. Although it takes a relatively long time to acquire the rate of change in the amount of electric power Ra2, it is possible to improve the accuracy of determining the state of the secondary battery 100. Furthermore, in the battery state detection method according to the fourth embodiment, the state (degree of deterioration) of the secondary battery 100 is determined by combining the determination based on the index value indicating the magnitude of the fluctuation 200 (step S04) and the determination based on the rate of change in the amount of electric power Ra2 (step S073). This allows the state of the secondary battery 100 to be determined more appropriately.

[0071] As shown in an example in FIG. 17, the amount of charge energy in the initial state of the secondary battery 100 to be detected and after operation, and the amount of energy threshold R2 that is the criterion for determining the rate of change in the amount of energy Ra2 are also used. th Such information is stored in the storage unit 60 for each type of secondary battery 100. When performing state determination, the state determination unit 42 reads out the necessary information from the storage unit 60 and determines the state of the secondary battery 100 as described above.

[0072] (Embodiment 5) <Outline of the battery recovery device> Fig. 18 is a diagram showing an example of the overall configuration of a battery recovery device of embodiment 5. As shown in Fig. 18, the battery recovery device 2 of embodiment 5 is configured to include the battery state detection device 1 of the above embodiment, and executes recovery processing for the secondary battery 100 according to the determination result of the state of the secondary battery 100 by the above-mentioned state determination unit 42. Furthermore, the battery recovery device 2 of this embodiment estimates the period until the secondary battery 100 enters a predetermined abnormal state, as necessary.

[0073] The calculation unit 40A of the battery recovery device 2 according to the fifth embodiment includes a recovery processing unit 44 and a period estimation unit 45 in addition to the index value acquisition unit 41, the state determination unit 42, and the display control unit 43 described above.

[0074] The recovery processing unit 44 executes a recovery process of applying a recovery waveform to the secondary battery 100 according to the determination result of the state determination unit 42. In this example, the reference waveform generation unit 10 functions as a recovery waveform generation unit that generates a recovery waveform. The recovery processing unit 44 applies the recovery waveform to the secondary battery 100 via this reference waveform generation unit (recovery waveform generation unit) 10. Since known techniques can be used for the recovery process of the secondary battery 100, a detailed description of the recovery process will be omitted. The recovery processing unit 44 also determines a period during which the recovery waveform is applied to the secondary battery 100 (hereinafter also referred to as a recovery waveform application period) according to the index value acquired by the index value acquisition unit 41, for example, the magnitude of the peak-to-peak value ΔV of the fluctuation 200.

[0075] The period estimation unit 45 estimates the period (hereinafter also referred to as abnormal transition period) during which the secondary battery 100 changes from its current state (level of degradation) to a predetermined abnormal state based on the index value, for example, the magnitude of the peak-to-peak value ΔV of the fluctuation 200. In this example, when the state determination unit 42 determines that the secondary battery 100 is in the deteriorated state, the period during which the secondary battery 100 changes from the deteriorated state to the abnormal state is estimated as the abnormal transition period. However, the timing at which the period estimation unit 45 estimates the abnormal transition period is not particularly limited, and may be, for example, when the secondary battery 100 is in a normal state. In this case, the period estimation unit 45 estimates the period during which the secondary battery 100 changes from the normal state to the abnormal state as the abnormal transition period. The recovery waveform application period and the abnormal transition period can be estimated based on changes in the magnitude of the fluctuation 200, changes in the charging voltage, and the like when recovery processing for the secondary battery 100 was previously performed.

[0076] The battery recovery device 2 of this embodiment configured as described above can appropriately detect the state (degree of deterioration) of the secondary battery 100 and, based on the detection result, can execute recovery processing of the secondary battery 100 at a suitable timing. An example of a battery recovery method using the battery recovery device 2 of this embodiment will be described below.

[0077] 19 is a flowchart showing an example of a battery recovery method according to embodiment 5. Note that the steps (steps S01 to S09) up to the state determination of the secondary battery 100 by the state determination unit 42 are the same as those in embodiment 1, and therefore detailed description of these steps will be omitted.

[0078] As shown in FIG. 19, in step S07, the peak-to-peak value ΔV as the index value is set to a second threshold value ΔV th2 If the above is the case (step S07: Yes), and the state determination unit 42 determines that the secondary battery 100 is in an abnormal state (step S09), then in step S021, the recovery processing unit 44 executes a recovery process to apply a predetermined recovery waveform to the secondary battery 100 (recovery step). At this time, the recovery processing unit 44 determines the period for applying the recovery waveform to the secondary battery 100 (recovery waveform application period) depending on the magnitude of the current index value (in this example, the peak-to-peak value ΔV).

[0079] The recovery waveform application period can be determined based on, for example, a change in the index value or a change in the charging voltage when the recovery process of the secondary battery 100 was previously performed. For example, as shown by the dotted line in FIG. 20, when the peak-to-peak value ΔV of the fluctuation 200 is greater than or equal to a predetermined second threshold value V th2 When the state determination unit 42 determines that the secondary battery 100 is in an abnormal state, recovery processing is executed. When the state of the secondary battery 100 is restored to a normal state by this recovery processing, the fluctuation 200 becomes smaller during the recovery period as shown by the solid line in FIG. 20, and the peak-to-peak value ΔV, which is the index value, becomes equal to or smaller than the first threshold ΔV th1 It has been confirmed that it is smaller than

[0080] 21, information about past recovery processes, such as the magnitude of the index value before the recovery process (degree of deterioration), the voltage of the recovery waveform (recovery voltage), and the recovery period, is stored in advance in the storage unit 60 in accordance with the type of secondary battery 100. In the example of FIG. 21, there is one piece of information about the recovery process for each battery type, but in reality, multiple pieces of information are stored for each battery type. Therefore, the recovery processing unit 44 can refer to the information in the storage unit 60 and appropriately determine the recovery process period for the current recovery process based on changes in the index value during the past recovery process.

[0081] FIG. 22 is a diagram showing an example of changes in the charge voltage of a secondary battery before and after a recovery process is performed. The dotted line in FIG. 22 shows the change in the charge voltage of the secondary battery 100 before the recovery process is performed, i.e., the secondary battery 100 determined to be in an abnormal state. On the other hand, the solid line in FIG. 22 shows the change in the charge voltage of the secondary battery 100 after the recovery process is performed. As can be seen from this diagram, by performing a recovery process for a predetermined period of time on a secondary battery 100 determined to be in an abnormal state by the state determination unit 42, the charge voltage of the secondary battery 100 increases (recovers). Furthermore, changes in charge voltage and recovery periods in past recovery processes are also stored in advance in the storage unit 60 corresponding to the type of secondary battery 100. Therefore, by referring to the information in the storage unit 60, the recovery processing unit 44 can appropriately determine the recovery process period for the current recovery process based on the change in charge voltage in the past recovery process.

[0082] Returning to the flowchart of FIG. 18, in step S07, the peak-to-peak value ΔV as the index value is set to a second threshold value ΔV th2 (step S07: No), the state determination unit 42 determines that the state of the secondary battery 100 is a degraded state (step S09). Next, in step S022, the period estimation unit 45 estimates an abnormal transition period during which the secondary battery 100 transitions from its current state to a predetermined abnormal state based on the magnitude of the peak-to-peak value ΔV as the index value. In this example, the abnormal transition period is estimated as the period during which the secondary battery 100 transitions from a degraded state to an abnormal state.

[0083] The abnormal transition period can be estimated, similarly to the recovery waveform application period, based on, for example, changes in index values ​​or changes in charging voltage when recovery processing was previously performed on the secondary battery 100. The abnormal transition period does not exactly coincide with the recovery waveform application period. However, the abnormal state transition period can be accurately estimated by performing calculations based on changes in index values ​​or changes in charging voltage when recovery processing was previously performed on the secondary battery 100.

[0084] After the recovery process in step S021 or the period estimation in step S022 is completed, in step S010, the display control unit 43 causes the display unit 50 to display the result of the recovery process or the period estimation together with the determination result of the state of the secondary battery 100. After the recovery process in step S021 is completed, the state determination unit 42 may re-determine the state of the secondary battery 100, and the result of the re-determination may be included as the result of the recovery process.

[0085] As described above, according to the battery recovery method of this embodiment, the state (degree of deterioration) of the secondary battery 100 can be appropriately detected, and based on the detection result, recovery processing of the secondary battery 100 can be performed at a suitable timing.

[0086] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present disclosure. Except for essential components, components can be added, deleted, or replaced in each embodiment. Unless otherwise specified, each component can be singular or plural. A combination of each embodiment is also possible. [Explanation of symbols]

[0087] 1... battery state detection device, 2... battery recovery device, 10... reference waveform generation unit, 20... applied waveform generation unit, 21... voltage controlled oscillator (VCO), 22... amplifier, 23... correction circuit, 30... detection unit, 31... resistor, 32... voltmeter, 40... calculation unit, 41... index value acquisition unit, 42... state determination unit, 43... display control unit, 44... recovery processing unit, 45... period estimation unit, 50... display unit, 60... memory unit, 100... secondary battery, 101... battery cell

Claims

1. A battery state detection device for detecting the state of a secondary battery, a reference waveform generating unit that generates a reference waveform; an application waveform output unit that outputs an application waveform to be applied to the secondary battery based on the reference waveform and performs feedback correction of a phase difference between the reference waveform and the application waveform; a detection unit that detects an output signal waveform output from the secondary battery while the applied waveform is applied; an index value acquiring unit that acquires an index value indicating the magnitude of fluctuation occurring in the output signal waveform based on the detection result of the detecting unit; Battery status detection device.

2. 2. The battery state detection device according to claim 1, the index value acquisition unit acquires, as the index value, the magnitude of the fluctuation or a period during which the fluctuation occurs; Battery status detection device.

3. 3. The battery state detection device according to claim 2, the index value acquisition unit acquires a peak value of the fluctuation as the index value. Battery status detection device.

4. 2. The battery state detection device according to claim 1, The fluctuation occurs when there is a phase difference between the applied waveform and the reference waveform. Battery status detection device.

5. 5. The battery state detection device according to claim 4, The fluctuation is jitter caused by a phase difference between the applied waveform and the reference waveform. Battery status detection device.

6. 2. The battery state detection device according to claim 1, a state determination unit that determines a state of the secondary battery based on the magnitude of the index value acquired by the index value acquisition unit; Battery status detection device.

7. 7. The battery state detection device according to claim 6, The state determination unit If the index value is smaller than a preset threshold value, the secondary battery is determined to be in a normal state; If the index value is equal to or greater than the threshold value, the secondary battery is determined to be in an abnormal state. Battery status detection device.

8. 8. The battery state detection device according to claim 7, The abnormal state is divided into a plurality of categories, When the state determination unit determines that the state of the secondary battery is the abnormal state, the state determination unit further determines to which category the abnormal state of the secondary battery falls. Battery status detection device.

9. 9. The battery state detection device according to claim 8, the state determination unit determines which category the abnormal state of the secondary battery falls into based on a change in charging voltage of the secondary battery. Battery status detection device.

10. 9. The battery state detection device according to claim 8, the state determination unit determines which category the abnormal state of the secondary battery falls into based on a rate of change of an output impedance of the secondary battery relative to an initial value. Battery status detection device.

11. 9. The battery state detection device according to claim 8, the state determination unit determines which category the abnormal state of the secondary battery falls into based on a change in the amount of chargeable energy of the secondary battery from an initial value. Battery status detection device.

12. 9. The battery state detection device according to claim 8, a period estimation unit that estimates a period until the secondary battery enters the predetermined abnormal state category based on the magnitude of the index value; Battery status detection device.

13. 2. The battery state detection device according to claim 1, The application waveform output unit includes a phase-locked loop circuit. Battery status detection device.

14. 2. The battery state detection device according to claim 1, The secondary battery is a lead-acid battery. Battery status detection device.

15. 7. The battery state detection device according to claim 6, the secondary battery is a lead-acid battery, the state determination unit determines that the secondary battery is in an abnormal state due to sulfation when the index value is equal to or greater than a predetermined threshold value; Battery status detection device.

16. The battery state detection device according to claim 15; a recovery processing unit that applies a recovery waveform to the secondary battery in accordance with a determination result of the state determination unit. Battery recovery device.

17. 17. The battery recovery device according to claim 16, the recovery processing unit determines a period for applying the recovery waveform to the secondary battery in accordance with the magnitude of the index value. Battery recovery device.

18. A battery state detection method for detecting a state of a secondary battery, comprising: a detection step of detecting an output signal waveform output from the secondary battery in a state where a phase difference between a reference waveform and an applied waveform that is output based on the reference waveform and applied to the secondary battery is feedback corrected; an acquisition step of acquiring an index value indicating the magnitude of fluctuation occurring in the output signal waveform from the detection result of the detection step; a determination step of determining a state of the secondary battery based on the magnitude of the index value. Battery status detection method.

19. 19. The battery state detection method according to claim 18, In the determination step, determining that the secondary battery is in a normal state when the index value is smaller than a preset threshold value; determining that the secondary battery is in an abnormal state when the index value is equal to or greater than the threshold value; Battery status detection method.

20. A battery recovery method for recovering the charge capacity of a secondary battery that is a lead-acid battery, comprising: a detection step of detecting an output signal waveform output from the secondary battery while feeding back a phase difference between a reference waveform and an applied waveform that is output based on the reference waveform and applied to the secondary battery; an acquisition step of acquiring an index value indicating the magnitude of fluctuation occurring in the output signal waveform from the detection result in the detection step; a determination step of determining a state of the secondary battery based on the magnitude of the index value; a recovery process of applying a recovery waveform to the secondary battery in accordance with the determination result of the determination process, the recovery step is executed when the index value is equal to or greater than a predetermined threshold value in the determination step and the secondary battery is determined to be in an abnormal state due to sulfation. How to recover battery.

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