Secondary battery degradation estimation method and secondary battery degradation estimation device

Abstract

The present invention provides, in relation to estimating the degradation state of a secondary battery installed in a vehicle, a secondary battery degradation estimation method and a secondary battery degradation estimation device capable of estimating the degradation state with higher accuracy by accounting for a relaxation phenomenon of the secondary battery subject to degradation state estimation. The present invention comprises: steps (ST3, ST4) for setting when to start measuring the impedance of a secondary battery on the basis of a relaxation phenomenon of the secondary battery, with reference to when a vehicle power source is turned off in a vehicle (V) equipped with the secondary battery subject to degradation estimation; a step (ST9) for measuring the impedance; and a step (ST14) for estimating the degradation state of the secondary battery using the measured impedance.

Description

Secondary battery deterioration estimation method and secondary battery deterioration estimation device

[0001] FIELD Embodiments of the present invention relate to a method and an apparatus for estimating deterioration of a secondary battery.

[0002] Patent Literature 1 discloses a method for detecting the state of a power storage device, which estimates the SOH of the power storage device from the internal impedance of the power storage device. Specifically, the method measures the internal resistance of the power storage device using a signal of a first frequency at which the internal impedance of the power storage device decreases with increasing temperature, and calculates the initial SOH from the measured value.

[0003] The internal impedance of the power storage device is measured using a signal of a second frequency, which increases with increasing temperature, and the internal temperature of the power storage device is calculated from the measured value.The SOH of the power storage device is then estimated by correcting the initial SOH using the calculated internal temperature.

[0004] International Publication No. 2014 / 073208

[0005] In a storage battery (secondary battery), a concentration gradient of ions occurs between the positive and negative electrodes due to charging and discharging. However, this concentration gradient gradually disappears over time. This transition is referred to as a "relaxation phenomenon."

[0006] When the ion concentration gradient characteristic settles down, that is, when the relaxation phenomenon converges, the battery enters a stable state because the concentration gradient disappears. By measuring the impedance of the battery at this time, a more accurate estimation of the battery's degradation state can be performed.

[0007] However, in Patent Document 1, as described above, signals of two different frequencies are used to calculate the initial SOH and internal temperature, and then the final SOH of the storage battery is estimated. Therefore, attention is particularly focused on how accurately the internal temperature of the power storage device used to correct the initial SOH is calculated. In other words, even if the measurement accuracy is improved, unless the characteristics of the storage battery that is the object of measurement are taken into consideration, it is not possible to improve the accuracy of estimating the final degradation state of the storage battery.

[0008] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method and device for estimating the deterioration state of a secondary battery mounted on a vehicle, which can estimate the deterioration state with higher accuracy by taking into account the relaxation phenomenon of the secondary battery whose deterioration state is to be estimated.

[0009] The method for estimating deterioration of a secondary battery in an embodiment includes the steps of setting the timing for starting measurement of the impedance of the secondary battery based on the relaxation phenomenon of the secondary battery, with the time when the vehicle power supply of the vehicle equipped with the secondary battery to be subjected to deterioration estimation is turned off as a reference, measuring the impedance, and estimating the deterioration state of the secondary battery using the measured impedance.

[0010] In addition, the secondary battery deterioration estimation device in the embodiment includes a timing unit that measures the time until the measurement of the impedance of the secondary battery, which is set based on the relaxation phenomenon of the secondary battery, based on the time when the vehicle power supply of the vehicle equipped with the secondary battery that is the subject of deterioration estimation is turned off, an impedance measurement unit that measures the impedance based on a measurement start trigger that is a trigger for starting measurement of the impedance of the secondary battery issued by the timing unit's measurement of the time, and a deterioration state determination unit that uses the measured impedance to estimate the deterioration state of the secondary battery.

[0011] The present invention adopts such a method and device for estimating deterioration of a secondary battery, and therefore, when estimating the deterioration state of a secondary battery installed in a vehicle, measurements can be performed that take into account the relaxation phenomenon of the secondary battery whose deterioration state is to be estimated, thereby enabling a more accurate estimation of the deterioration state.

[0012] FIG. 1 is a block diagram showing the overall configuration of a vehicle including a deterioration estimation device for a secondary battery according to an embodiment of the present invention. FIG. 2 is a block diagram showing the internal configuration of the deterioration estimation device for a secondary battery according to an embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating the relationship between lithium ion concentration gradient characteristics and operation of the deterioration estimation device for a secondary battery when a charging process is not performed on a secondary battery according to a first embodiment of the present invention. FIG. 4 is an explanatory diagram illustrating the relationship between lithium ion concentration gradient characteristics and operation of the deterioration estimation device for a secondary battery when a charging process is performed on a secondary battery according to the first embodiment of the present invention. FIG. 5 is a flowchart showing the flow of a deterioration estimation method for a secondary battery according to the first embodiment of the present invention. FIG. 6 is a flowchart showing the flow of a deterioration estimation method for a secondary battery according to the first embodiment of the present invention. FIG. 7 is a flowchart showing the flow of a deterioration estimation method for a secondary battery according to the second embodiment of the present invention. FIG. 8 is a flowchart showing the flow of a deterioration estimation method for a secondary battery according to the second embodiment of the present invention. 1 is a diagram illustrating a relationship between a concentration gradient characteristic of lithium ions in a secondary battery and the operation of a deterioration estimation device for a secondary battery according to a fourth embodiment of the present invention; and FIG. 2 is a flowchart illustrating a flow of a deterioration estimation method for a secondary battery according to the fourth embodiment of the present invention.

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the drawings are schematic and may differ from the actual product. Furthermore, the embodiments of the present invention shown below are merely examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the structure, arrangement, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0014] (First embodiment) Fig. 1 is a block diagram showing the overall configuration of a vehicle V including a secondary battery deterioration estimation device 1 according to an embodiment of the present invention. The secondary battery deterioration estimation device 1 is used to estimate the deterioration state of a secondary battery. The target of estimation is a secondary battery mounted on the vehicle V. Therefore, the vehicle V according to the embodiment of the present invention can be any type, such as an electric vehicle or a hybrid vehicle, as long as it is equipped with a secondary battery.

[0015] Vehicle V is equipped with a charging port CP, and by connecting a charger C to the charging port CP, the secondary battery can be charged. In this embodiment of the present invention, the secondary battery whose degradation state is to be estimated is a battery that can be charged and discharged multiple times, such as a battery mounted on a vehicle or a storage battery mounted on an electric vehicle and used to provide driving force. There are various types of "secondary batteries," but a lithium-ion battery can be mentioned here, for example.

[0016] 1 shows a battery pack BP in which multiple secondary batteries are connected in series. A current sensor CS is connected to the battery pack BP, and measures, for example, the current charged from a charger C via a charging port CP. The battery pack BP (secondary battery) and the current sensor CS are connected to a secondary battery deterioration estimation device 1 (hereinafter referred to as "deterioration estimation device 1" as appropriate).

[0017] As described above, the deterioration estimation device 1 is responsible for estimating the deterioration state of a secondary battery, but more specifically, it measures the internal impedance (hereinafter referred to as "impedance" as appropriate) of the secondary battery and estimates the deterioration state of the secondary battery based on the measurement results.

[0018] The deterioration estimation device 1 is connected to a BMS (Battery Management System) 2, and further connected to a control device (e.g., a vehicle control unit) 3 that controls the entire vehicle. The deterioration state of the secondary battery estimated by the deterioration estimation device 1 is transmitted to the battery monitoring system 2 and the vehicle control unit 3, and is notified to the user of the vehicle V, for example.

[0019] The deterioration estimation device 1 may estimate the deterioration state of the secondary battery by being controlled by the battery monitoring system 2, or may autonomously perform processing to estimate the deterioration state of the secondary battery.

[0020] Furthermore, the degradation state of the secondary battery estimated by the degradation estimation device 1 can be transmitted to the outside of the vehicle V via an on-board communication unit 4 and an antenna A connected to the vehicle control unit 3. The information indicating the degradation state of the secondary battery of the vehicle V transmitted to the outside of the vehicle is stored, for example, in a server provided on a network and is used, for example, when inspecting the vehicle V.

[0021] The secondary battery is charged, and the charged power is discharged from the secondary battery (battery pack BP) and transmitted to the drive motor M via the inverter I. The drive motor M is connected to the drive parts of the vehicle V, such as the tires, and the secondary battery provides drive power to the vehicle V.

[0022] Next, the functions of each component of the deterioration estimation device 1 will be described with reference to the drawings. Fig. 2 is a block diagram showing the internal configuration of the deterioration estimation device 1 for a secondary battery according to an embodiment of the present invention. As shown in Fig. 2, the deterioration estimation device 1 includes a timer 11, a measurement control unit 12, an impedance measurement unit 13, and a deterioration state determination unit 14.

[0023] 2 shows only the components necessary for the degradation state estimation method according to the embodiment of the present invention. Therefore, in addition to the components shown in FIG. 2, components for executing functions other than those performed by the components shown in FIG. 2 may be provided.

[0024] The functions of the deterioration estimation device 1 described below are realized by, for example, a measurement control unit 13 and a deterioration state determination unit 14, each of which is made up of a processor, executing a computer program stored in a storage unit (not shown). The processor may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit).

[0025] Furthermore, the deterioration estimation device 1 may be formed by dedicated hardware for executing each information processing described below. For example, the deterioration estimation device 1 may include a functional logic circuit set in a general-purpose semiconductor integrated circuit. The deterioration estimation device 1 may also include a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

[0026] The timer 11 measures various times set to determine the timing at which the impedance measurement unit 13 (described later) starts measuring the impedance of the secondary battery. Specifically, the timer 11 first measures a measurement start wait time. The measurement start wait time is the time from when the vehicle power supply of the vehicle V is turned off until it becomes possible to measure the impedance. When the measurement start wait time arrives, the measurement control unit 12 (described later) issues a measurement start enable flag.

[0027] As described above, the method for estimating the degradation state of a secondary battery in this embodiment of the present invention focuses on the relaxation phenomenon of the secondary battery. Immediately after the power supply to the vehicle V is turned off, the vehicle V has been running and has been discharging, so the ion concentration gradient is large. Then, because discharging from the secondary battery ends when the power supply to the vehicle V is turned off, the ion concentration gradient gradually decreases over time.

[0028] When the concentration gradient becomes smaller, the secondary battery becomes stable, so by measuring the impedance in this state, a more accurate impedance value can be obtained, and as a result, the deterioration state of the secondary battery can be estimated with high precision. Therefore, the timer 11 starts measuring the measurement start waiting time when the power of the vehicle V is turned off.

[0029] This will be explained using Fig. 3. Fig. 3 is an explanatory diagram illustrating the relationship between the concentration gradient characteristics of lithium ions and the function of the deterioration estimation device 1 when the secondary battery according to the first embodiment of the present invention is not subjected to a charging process.

[0030] 3, multiple horizontal axes are shown, which indicate the passage of time from left to right, and the time point on the vertical axis shown on the far left is the time when the power of the vehicle V is turned off by the user.

[0031] 3, for convenience of explanation, the time when the user turned off the power of the vehicle V is set to "20:00." That is, "20:00" is the time when the user stopped the vehicle V after using it and turned off the power. Moving to the right from this point, that is, as time passes, the times of "6:00," "7:00," and "7:01" of the next day are shown.

[0032] Here, "6:00" is the time when the vehicle V is stopped and the power remains off. Meanwhile, "7:00" is the time when the user unlocks the vehicle V and the unlocking signal is received by the measurement control unit 12, which will be described later. And "7:01" is the time when the user, who unlocked and opened the door, gets into the vehicle V and turns on the power of the vehicle V.

[0033] 3, the top row shows the gradient characteristics of the ion concentration of the lithium ion battery. The middle row below the gradient characteristics of the ion concentration shows the measurement start wait time measured by the timer 11. The bottom row shows the processing of the impedance measurement unit 13 over time.

[0034] In Figure 3, the ion concentration characteristic is shown by a thick solid line, and the gradient of the ion concentration is large immediately after the power to the vehicle V is turned off. Then, as time passes, the gradient of the ion concentration gradually decreases, and by the time the timer unit 11 receives the unlock signal, the gradient of the ion concentration has almost disappeared. This is the state in which the relaxation phenomenon has converged.

[0035] As shown in the middle section, the timing unit 11 starts measuring the measurement start waiting time when the user turns off the power to the vehicle V. In Fig. 3, the measurement start waiting time is shown as the time from "20:00" when the power to the vehicle V is turned off to "6:00" the following day. The fact that the time from "20:00" to "6:00" is the measurement start waiting time will be described later.

[0036] The timer 11 also measures a measurement standby time, which is the time from when the vehicle power supply of the vehicle V is turned off until the impedance measurement unit 13 actually starts measuring the impedance of the secondary battery. As such, the measurement standby time is closely related to the start of impedance measurement by the impedance measurement unit 13, and therefore, in Figure 3, the measurement standby time is shown next to the impedance measurement unit 13, which will be described later.

[0037] The measurement control unit 12 controls the timing unit 11 and the impedance measurement unit 13, which will be described next. As described above, the timing unit 11 measures the measurement start waiting time from when the power supply of the vehicle V is turned off, and the measurement control unit 12 compares the timing information from the timing unit 11 with a preset relaxed specified time.

[0038] The specified relaxation time is a time indicating that the state of the secondary battery is suitable for measuring the impedance in the transition of the relaxation phenomenon, and is determined for each secondary battery whose degradation state is to be estimated.

[0039] That is, as described above, a relaxation phenomenon occurs in secondary batteries, and therefore, time is required for the secondary battery to reach a state suitable for impedance measurement. Therefore, the transition of the relaxation phenomenon is linked to time, and the time for the secondary battery to reach a state suitable for impedance measurement is set as the specified relaxation time. The specified relaxation time is, for example, experimentally determined and set for each secondary battery, and is stored in, for example, a memory unit (not shown) in the degradation estimation device 1.

[0040] The measurement control unit 12 compares the measurement start waiting time with the relaxed specified time, and if it determines that the measurement start waiting time has elapsed for a time equal to or longer than the relaxed specified time, it issues a measurement start possible flag. Issuing the measurement start possible flag enables the impedance measurement unit 13 to measure impedance after this issuance.

[0041] 3, the measurement start possible flag issued by the measurement control unit 12 is shown next to the timing unit. For example, the measurement control unit 12 compares the measurement start waiting time measured by the timing unit 11 with the relaxed specified time, and when the measurement start waiting time becomes equal to or greater than the relaxed specified time at "6:00," the measurement control unit 12 issues the measurement start possible flag. Therefore, the measurement start possible flag is shown at "6:00" in FIG.

[0042] In this way, the measurement control unit 12 issues the measurement start possible flag, but the impedance measurement unit 13 does not yet start measuring the impedance. In order for the impedance measurement unit 13 to actually start measuring the impedance, it must wait for the measurement start trigger to be issued by the measurement control unit 12.

[0043] The measurement control unit 12 sets a measurement start trigger based on the frequency distribution of the times when a user of a vehicle V equipped with a secondary battery whose degradation state is to be estimated unlocks the vehicle V after turning off the power to the vehicle V.

[0044] 3, the frequency distribution of the times at which users unlock the vehicle V is shown, with a peak at "7:00," which indicates the reception of an unlocking signal. In other words, this shows that users often unlock the vehicle V within approximately 1 to 2 minutes before and after "7:00."

[0045] That is, the user unlocks the vehicle V at approximately 7:00 in the morning, and turns on the power of the vehicle V at, for example, 7:01, to start using the vehicle V. Therefore, after the user unlocks the vehicle V, the vehicle V is used thereafter, and the gradient of the ion concentration becomes larger. As a result, the secondary battery transitions from a stable state to an unstable state.

[0046] As described above, in order to accurately measure the impedance value necessary for estimating the degradation state of the secondary battery, it is necessary for the secondary battery to be in a stable state. Therefore, it is preferable that the degradation estimation device 1 finishes measuring the impedance before the user unlocks the vehicle V.

[0047] Therefore, the measurement control unit 12 needs to cause the impedance measurement unit 13 to start measuring the impedance at a timing when it is possible to finish measuring the impedance after issuing the measurement start possible flag and before the user performs the unlocking process for the vehicle V. Then, the measurement of the impedance by the impedance measurement unit 13 is started when the measurement control unit 12 issues a measurement start trigger.

[0048] Therefore, in the first embodiment, when the measurement control unit 12 issues a measurement start trigger, the timing of issuing the trigger is determined based on the frequency distribution of the time when the user unlocks the vehicle V. Specifically, the measurement control unit 12 first calculates the average unlocking time based on, for example, the frequency distribution of the time when the vehicle V is unlocked.

[0049] The measurement control unit 12 calculates the time by subtracting the time when the user is unlikely to unlock the door and the time required to measure the impedance (measurement time) from the calculated unlocking time, and then issues a measurement start trigger at the calculated time.

[0050] The measurement start trigger issued by the measurement control unit 12 must be issued only after the measurement start enable flag is issued, because the relaxation phenomenon must have converged to some extent in the secondary battery whose degradation state is to be estimated.

[0051] The measurement standby time is the time from when the user turns off the power to the vehicle V to when the measurement start trigger is issued. Furthermore, in Figure 3, the measurement implementation period is the time from when the measurement start possible flag is issued to when it is considered unlikely that the user will unlock the vehicle V.

[0052] The measurement control unit 12 sets the measurement start trigger so that the secondary battery is in a relaxed state and before the user begins using the vehicle V, thereby making it possible to measure impedance accurately while ensuring as much measurement time as possible.

[0053] Therefore, if the measurement start trigger is not included in the measurement implementation period, the required measurement time cannot be secured. It is also possible that the required measurement time will be longer than the measurement implementation period. In such cases, the impedance measurement may not be completed by the time the user unlocks the vehicle V. Therefore, in such cases, the impedance measurement is not performed.

[0054] The impedance measurement unit 13 measures the impedance at preset frequency points in the secondary battery. Furthermore, the impedance is measured in the order of low frequency, medium frequency, and high frequency. This is because the lower the frequency, the longer the cycle and therefore the longer the measurement time. Therefore, by measuring the low-frequency impedance immediately after the measurement start trigger is issued, the time required to complete the impedance measurement before the user starts using the vehicle V can be secured.

[0055] On the other hand, in the case of high frequencies, one cycle is short, so measurement is completed in a very short time. Therefore, even if the impedance measurement is performed close to the time when the user starts using the vehicle V, there is little possibility that the scheduled measurement will be interrupted. Therefore, the impedance measurement unit 13 measures the impedance in the order of low frequency to high frequency.

[0056] As described above, the measurement control unit 12 issues a measurement start trigger so that the impedance measurement unit 13 finishes measuring the impedance before the user unlocks the vehicle V. However, there is a possibility that the user may unlock the vehicle V at a time outside the frequency distribution or may start using the vehicle V while high-frequency impedance is being measured. If the measurement control unit 12 receives an unlock signal at such a timing, it is possible that the measurement of the impedance required to estimate the deterioration state may not be completed.

[0057] For this reason, as described above, the measurement is started from the low frequency impedance, but if the user performs the unlocking process while the impedance measurement unit 13 is measuring the impedance, the measurement control unit 12 will interrupt the impedance measurement. For example, if the measurement is interrupted while measuring the low frequency or medium frequency impedance, the measurement of the subsequent impedance will be terminated and the impedance of a preset high frequency will be measured.

[0058] That is, if the impedance measurement is interrupted before the high-frequency impedance measurement is started, the high-frequency impedance measurement results cannot be obtained at all, which makes it difficult to accurately estimate the deterioration state of the secondary battery.

[0059] Therefore, high frequencies (essential frequencies) that are to be acquired as high-frequency impedance are set in advance. If the impedance measurement is interrupted before the high-frequency impedance is measured, the impedance at the scheduled high-frequency cannot be measured, but the impedance at least at the essential frequency is measured.

[0060] On the other hand, for the measurement results of impedance at frequency points in low or medium frequencies that could not be measured due to an interruption, for example, the measurement results of impedance at low or medium frequencies obtained immediately before are regarded as the results of the current measurement process.

[0061] The state of a secondary battery gradually deteriorates over a long period of time. Therefore, even if impedance measurement is interrupted, it is thought that this will not have a significant impact on estimating the state of deterioration, for example, as long as the next measurement result can be reliably obtained. Furthermore, rather than leaving the impedance value at a frequency point where measurement was not possible as missing, the state of deterioration can be estimated by substituting the impedance value measured immediately before.

[0062] Therefore, there is no significant impact even if the impedance measurement unit 13 interrupts the measurement while it is in progress. Furthermore, even if the measurement is continued and an inaccurate impedance measurement result is obtained, this may actually reduce the accuracy of the estimation of the deterioration state. Therefore, if, for example, the user unlocks the door while the impedance is being measured, the impedance measurement is interrupted as described above.

[0063] 3 shows the state of impedance measurement by the impedance measurement unit 13. As explained above, the impedance measurement unit 13 starts measuring impedance when a measurement start trigger is issued by the measurement control unit 12. Therefore, the impedance measurement unit 13 is not activated and remains in an OFF state during the period from when the power supply to the vehicle V is turned OFF until the measurement start trigger is issued (measurement standby time).

[0064] Then, when a measurement start trigger is issued, the impedance measurement unit 13 is started (turned ON) and impedance measurement is performed. As described above, since impedance measurement requires a measurement time, the impedance measurement unit 13 remains ON during the measurement time.

[0065] Then, when the impedance at the frequency point set for each frequency is measured, the impedance measurement unit 13 transitions from ON to OFF. This ends the impedance measurement. After this, the degradation state determination unit 14 performs a degradation state estimation process (described next) (in FIG. 3, this is represented as "degradation state estimation time").

[0066] The degradation state determination unit 14 determines the degradation state of the secondary battery mounted on the vehicle V using the measurement results of the impedance measured by the impedance measurement unit 13. The degradation state determination unit 14 also refers to information from the current sensor CS of the secondary battery (battery pack BP), etc. Note that the method used by the degradation state determination unit 14 to determine the degradation state of the secondary battery is a known method.

[0067] 3, the degradation state estimation (diagnosis) process by the degradation state determination unit 14 does not have to be executed immediately after the impedance measurement by the impedance measurement unit 13 is completed. The degradation state estimation process by the degradation state determination unit 14 may be executed at any time.

[0068] 3, which has been described so far, shows the gradient characteristics of the ion concentration when the secondary battery is not charged after the user has finished using the vehicle V and turned off the power. In contrast, FIG. 4 shows the gradient characteristics of the ion concentration when the secondary battery is charged. FIG. 4 is an explanatory diagram that explains the relationship between the gradient characteristics of lithium ion concentration and the function of the secondary battery degradation estimation device 1 when the secondary battery is charged according to the first embodiment of the present invention.

[0069] As shown in the upper part of Fig. 4, when the secondary battery is charged, the gradient of the ion concentration becomes smaller more quickly than when the secondary battery is not charged. In Fig. 4, the gradient characteristic of the ion concentration when the secondary battery is not charged is shown by the dotted line, and the difference is clear.

[0070] If the gradient of the ion concentration becomes small in this manner, the secondary battery will stabilize accordingly, and time for measuring the impedance can be secured. Therefore, when a charging process is performed, the specified relaxation time is set by subtracting the acceleration of the relaxation phenomenon due to the charging process.

[0071] In other words, the relaxed specified time when the charging process is performed is set to a shorter time than the relaxed specified time when the charging process is not performed. Therefore, the waiting time for the start of measurement is shortened accordingly, and it is possible to start measuring the impedance earlier.

[0072] 3, the measurement start possible flag is issued at "6:00", while in the explanatory diagram shown in Fig. 4, the measurement start possible flag is issued at "4:00" after subtracting the promotion of the relaxation phenomenon due to the charging process. Note that the extent to which the promotion of the relaxation phenomenon due to the charging process should be is determined, for example, by experiment.

[0073] [Operation] Next, a process for estimating the degradation state of a secondary battery by the degradation estimation device 1 described above will be described along the process flow. Figures 5 to 7 are flowcharts showing the flow of the method for estimating degradation of a secondary battery in the first embodiment of the present invention.

[0074] First, as a prerequisite for the deterioration estimation device 1 to start the process of measuring the internal impedance of the secondary battery, it is determined whether the power supply to the vehicle V has been turned off (ST1). This is determined by transmitting a signal indicating whether the power supply to the vehicle V is on or off to the measurement control unit 12. If the measurement control unit 12 does not receive this signal, this means that the power supply to the vehicle V has not been turned off (NO in ST1), and in this case the deterioration estimation device 1 enters a standby state.

[0075] On the other hand, as shown at the "20:00" stage in Figures 3 and 4, when the measurement control unit 12 receives a power OFF signal for the vehicle V (YES in ST1), it is determined whether or not the charging process has started for the vehicle V (ST2).

[0076] When the measurement control unit 12 determines that charging has started (YES in ST2), the specified relaxation time is set by subtracting the relaxation promotion amount due to charging (ST3), as described with reference to Fig. 4. Of course, the specified relaxation time by subtracting the relaxation promotion amount may be set in advance, and the measurement control unit 12 may acquire information on the specified relaxation time from the storage unit, for example.

[0077] On the other hand, if the charging process is not executed (NO in ST2), the specified relaxation time is used without subtracting the aforementioned relaxation promotion time. Then, the timer 11 starts timing the measurement start waiting time and the measurement standby time (ST4).

[0078] The measurement control unit 12 compares the time information from the timer unit 11 with the relaxed specified time (ST5). If the result is that the measurement start waiting time is equal to or longer than the relaxed specified time (YES in ST5), a measurement start possible flag is issued (ST6).

[0079] This is as shown by "6:00" in Figure 3 and "4:00" in Figure 4. The reason why the time at which the measurement start possible flag is issued differs between Figure 3 and Figure 4 is, as described above, whether or not a charging process was performed after the power supply of the vehicle V was turned off. That is, if a charging process was performed, the acceleration of the mitigation phenomenon due to the charging process is subtracted when setting the specified mitigation time.

[0080] The measurement control unit 12 then determines whether the measurement standby time being measured by the timer unit 11 has elapsed (ST7). As described above, the measurement standby time is set by the measurement control unit 12, for example, together with the setting of the measurement start trigger based on the frequency distribution of the unlocking process of the vehicle V by the user.

[0081] If the measurement control unit 12 determines that the measurement standby time has not yet elapsed (NO in ST7), the measurement control unit 12 continues to wait until the measurement standby time has elapsed.

[0082] On the other hand, if the measurement control unit 12 determines that the measurement standby time has elapsed (YES in ST7), a measurement start trigger is issued (ST8). The issuance of the measurement start trigger causes the impedance measurement unit 13 to start measuring the impedance (ST9 in FIG. 6). In terms of FIGS. 3 and 4, this is after 6:00 and before 7:00, when the unlocking process was performed.

[0083] As described above, the impedance measurement unit 13 measures the impedance at a predetermined frequency point for each frequency. When measuring the impedance, the impedance measurement unit 13 first measures the low-frequency impedance, then the medium-frequency impedance, and then the high-frequency impedance.

[0084] While the impedance measurement unit 13 is measuring the impedance, the measurement control unit 12 determines whether the user has unlocked the vehicle V, i.e., whether an unlocking signal has been received (ST10). Note that in the flowchart of FIG. 6, this process is represented as "Unlocking event occurred?"

[0085] If the measurement control unit 12 does not receive an unlock signal while the impedance measurement unit 13 is measuring the impedance (NO in ST10), it determines whether the impedance measurement unit 13 has finished measuring the impedance (ST11).

[0086] If the measurement has not been completed (NO in ST11), the process returns to step ST10, where the measurement control unit 12 continues to determine whether or not an unlocking event has occurred and whether or not the measurement of impedance has been completed.

[0087] On the other hand, if the measurement control unit 12 determines that the impedance measurement by the impedance measurement unit 13 has been completed (YES in ST11), the measured impedance value is transmitted from the impedance measurement unit 13 to the deterioration state determination unit 14.

[0088] Then, the degradation state determination unit 14 executes a process of estimating the degradation state of the secondary battery using the impedance measured by the degradation state determination unit 14 (ST12). This process indicates the process performed by the impedance measurement unit 13 in Figs. 3 and 4 after the transition from the ON state to the OFF state.

[0089] However, as described above, the degradation state determination unit 14 does not necessarily have to perform the process of estimating the degradation state of the secondary battery at this point.

[0090] The measurement control unit 12 again determines whether an unlocking event has occurred (ST13). If the user has not unlocked the vehicle V, i.e., if the measurement control unit 12 has not received an unlocking signal (NO in ST13), the measurement control unit 12 enters standby mode. On the other hand, if the user has unlocked the vehicle V (an unlocking event has occurred) and the measurement control unit 12 has received an unlocking signal (YES in ST13), the measurement control unit 12 further determines whether the vehicle system has been started (ST14).

[0091] Here, the vehicle system being started means that the user has started the engine of the vehicle V. The processing by the measurement control unit 12 here is the processing shown at "7:00" and "7:01" in Figures 3 and 4.

[0092] If the vehicle system does not start after the user unlocks the vehicle V (NO in ST14), the measurement control unit 12 waits. On the other hand, if the measurement control unit 12 receives a signal indicating that the vehicle system has been started by the user (YES in ST14), the previous battery state information is updated using information indicating the deterioration state of the secondary battery estimated by the deterioration state determination unit 14 (ST15).

[0093] The above describes the flow when the internal impedance of a secondary battery is measured by the deterioration estimation device 1. However, depending on the situation, the measurement may be interrupted or the impedance may not be measured at all. These cases will now be described.

[0094] First, a case will be described in which the impedance measurement by the impedance measurement unit 13 is interrupted. Such an interruption occurs when the user unlocks the vehicle V while the impedance measurement unit 13 is measuring the impedance (YES in ST10 of FIG. 6).

[0095] After the unlocking process is performed, it is expected that the user will use the vehicle V. When the vehicle is used, the gradient of the ion concentration gradually increases, making it difficult to accurately measure the impedance. Therefore, when such an unlocking event occurs, the measurement control unit 12 suspends the impedance measurement that has been performed up to that point (ST16).

[0096] As described above, the impedance measurement unit 13 measures the impedance at preset frequency points in order from the lowest frequency impedance. Therefore, for example, if measurement of the low frequency impedance or the mid frequency impedance is interrupted, measurement of the high frequency impedance will not be performed at all.

[0097] Therefore, in order to avoid a situation in which no high frequency impedance is measured even when the impedance measurement is interrupted, only the impedance at a pre-set essential frequency is measured at high frequencies (ST17).

[0098] On the other hand, for example, if the measurement of low-frequency impedance or medium-frequency impedance is interrupted, there will be frequency points that are not measured among the frequency points set for the low-frequency or medium-frequency. In such a case, the measurement control unit 12 acquires the most recent measurement results for the unmeasured frequency points, for example, from the storage unit, and uses these as the measurement results for the interrupted impedance measurement by the impedance measuring unit 13 (ST18).

[0099] By performing such processing, it becomes possible to subsequently estimate the degradation state of the secondary battery by the degradation state determination unit 14. Furthermore, because degradation of a secondary battery progresses gradually over time, even if such processing is performed for one measurement process, it will not have a significant effect on the estimation of degradation of the secondary battery, for example, if the next time a reliable impedance measurement is performed.

[0100] Although the above explanation has been given using an example in which measurement of low-frequency impedance or mid-frequency impedance is interrupted, it is unclear when the unlocking event will occur. Therefore, for example, it is conceivable that the measurement of low-frequency impedance or mid-frequency impedance is completed, and the unlocking event will occur during measurement of high-frequency impedance.

[0101] In such a case, if the measurement is interrupted before the impedance at the required frequency is measured, the impedance at the required frequency is measured again as described above (ST17). However, since the measurement of the low-frequency impedance and the mid-frequency impedance has been completed, the process of step ST18, which satisfies the most recent measurement result, is not performed.

[0102] On the other hand, if an unlocking event occurs after the measurement of impedance at the required frequency has been completed and the measurement is interrupted, there is no need to measure impedance at the required frequency in step ST17.

[0103] Next, after the timer 11 starts measuring the measurement start waiting time, the measurement control unit 12 determines whether the measurement start waiting time is equal to or longer than the relaxed specified time (ST5 in FIG. 5). When the impedance measurement described above is performed, this corresponds to the case where the measurement start waiting time is equal to or longer than the relaxed specified time (YES in ST5). However, when the measurement start waiting time is shorter than the relaxed specified time (NO in ST5), the process described below is executed.

[0104] Here, a situation in which the measurement start waiting time is shorter than the specified relaxation time is, for example, a situation in which one hour has passed since the user turned off the power to the vehicle V, as shown in the explanatory diagram of FIG. 3. That is, at this point in time, the gradient of the ion concentration in the secondary battery is still large, and the relaxation phenomenon is progressing. Therefore, in this situation, the secondary battery is not in a state suitable for measuring impedance.

[0105] However, if the user unlocks the vehicle V in such a situation, there is a possibility that the user will use the vehicle V again. As described above, when the vehicle V is in use, it is difficult to measure an accurate impedance value even if the impedance is measured.

[0106] Therefore, the measurement control unit 12 compares the measurement start waiting time with the relaxed specified time and also determines whether or not an unlocking event has occurred. If there is no unlocking event (NO in ST19 in FIG. 7), it then determines whether or not the measurement start waiting time is equal to or greater than the relaxed specified time (ST5 in FIG. 5).

[0107] On the other hand, when the user unlocks the vehicle V and the measurement control unit 12 receives an unlock signal (YES in ST19), the impedance measurement process by the impedance measurement unit 13 is postponed (ST20).

[0108] Second Embodiment Next, a second embodiment of the present invention will be described. In the second embodiment, the same components as those described in the first embodiment are designated by the same reference numerals, and redundant descriptions of the same components will be omitted.

[0109] The pattern described in the first embodiment is a pattern in which the user uses the vehicle V every day, although the user may or may not charge the vehicle V after using it. The pattern described in the second embodiment is a pattern in which the user uses the vehicle V only on weekends. Therefore, the vehicle V is not used and is left parked on weekdays.

[0110] In other words, the gradient of the ion concentration, which has increased due to the user's use of the vehicle V over the weekend, becomes smaller by the next weekend when the vehicle V is used, and the relaxation phenomenon converges. Fig. 8 is an explanatory diagram illustrating the relationship between the concentration gradient characteristics of lithium ions in a secondary battery and the function of the secondary battery degradation estimation device 1 according to the second embodiment of the present invention.

[0111] The configuration of the explanatory diagram shown in Figure 8 is generally the same as the configuration of Figures 3 and 4 in that the upper row shows the gradient characteristics of ion concentration, the middle row shows the function of the timing unit, and the lower row shows the function of the impedance measurement unit.

[0112] However, the difference is that the "frequency distribution of unlocking (activation) times" which is shown collectively in the middle row of the timing section in the explanatory diagrams of Figures 3 and 4 is shown in separate rows between the row of the timing section and the upper row showing the gradient characteristics of ion concentration.

[0113] Looking at the "Frequency Distribution" column, "Sat" and "Sun" are shown to the left of the left vertical axis indicating the timing of powering off vehicle V. This indicates that vehicle V was unlocked on Saturdays and Sundays, and the user used vehicle V. Meanwhile, the days of the week from Monday (Mon) to Friday (Fri) are shown to the right of the left vertical axis indicating the timing of powering off vehicle V.

[0114] However, on these weekdays, the line showing the frequency distribution of unlocking times is flat, indicating that the user does not use vehicle V on weekdays. On the other hand, moving further to the right in the explanatory diagram of Figure 8, it is shown that the user also unlocks vehicle V on Saturdays and Sundays. Note that in the explanatory diagram of Figure 8, the weekday periods when vehicle V is not used are represented as "non-use periods (parked)."

[0115] In this pattern, where vehicle V is used only on weekends and not on weekdays, there is sufficient time between the last use of vehicle V and the next use for the relaxation phenomenon of the secondary battery to converge.

[0116] A method for estimating the deterioration state of the secondary battery in such a case will be described with reference to Fig. 8. Note that this case is based on the premise that the user performs charging processing after the power supply to the vehicle V is turned off.

[0117] After using vehicle V on Sunday, the user turns off the power to vehicle V. This point in time is represented by the vertical axis on the left side of the explanatory diagram in FIG. 8 . Charging processing then begins. The symbol O indicates the time required for the charging processing. Note that this example shows normal charging, not rapid charging. Because charging processing is performed, the mitigation of the decrease is more rapid than when charging processing is not performed, and the change in the gradient of the ion concentration is indicated by the solid line in FIG. 8 , for example.

[0118] Additionally, the measurement control unit 12 checks the period of non-use of the vehicle V equipped with the secondary battery whose degradation state is to be estimated. For example, the measurement control unit 12 checks the period of non-use from the past usage history of the vehicle V stored in the memory unit.

[0119] As described in the first embodiment, if the vehicle V is used every day, the timer unit 11 starts measuring the measurement start waiting time and the measurement waiting time when the power of the vehicle V is turned off. This is because there is a limited time for the impedance measurement unit 13 to measure the impedance with the secondary battery as stable as possible before the user performs the process of unlocking the vehicle V.

[0120] On the other hand, in the case of a weekend use pattern, there is a long period of non-use between the previous use and the next use of the vehicle V, so there is sufficient time for the secondary battery relaxation phenomenon to converge. Therefore, the measurement control unit 12 checks the non-use period and then sets the measurement start waiting time and the timing to start counting the measurement waiting time.

[0121] For convenience of explanation, the explanatory diagram shown in Figure 8 shows the state in which, as before, when the power supply to the vehicle V is turned off, the timing unit 11 starts measuring the measurement start waiting time and the measurement waiting time.

[0122] As explained in the first embodiment, the measurement control unit 12 determines whether the measurement start waiting time is equal to or greater than the relaxation specified time. As explained above, the relaxation specified time is set by subtracting the acceleration of the relaxation phenomenon due to the charging process. In the explanatory diagram of FIG. 8, the relaxation specified time is indicated by an arrow indicated by the symbol P.

[0123] Furthermore, when the measurement control unit 12 determines that the measurement start waiting time is equal to or longer than the relaxed specified time as a result of comparing the measurement start waiting time with the relaxed specified time, it issues a measurement start possible flag. Furthermore, the timing unit 11 starts timing the measurement implementation period shown in FIG.

[0124] Here, the measurement period in the second embodiment is not set based on the frequency distribution of the user's unlocking time, as described in the first embodiment. Indeed, in a weekend usage pattern, the time between the user's last use and the next use is longer than when the user uses the vehicle V every day. Therefore, a sufficiently long time can be ensured for the impedance measurement by the impedance measurement unit 13.

[0125] On the other hand, if the measurement waiting time is set unnecessarily long, the user may unlock the vehicle V as the next weekend approaches. If an unlocking event occurs, as described above, the impedance measurement by the impedance measurement unit 13 will be interrupted or postponed, which is not appropriate.

[0126] Therefore, a timeout period is set for the measurement implementation period that is set in advance. By setting this timeout, the measurement standby time is surely reached before the weekend approaches and an unlocking event occurs, and the measurement control unit 12 can issue a measurement start trigger.

[0127] The measurement control unit 12 determines whether a timeout has occurred for the measurement implementation period measured by the timing unit 11. If the measurement implementation period has reached a timeout, the measurement control unit 12 ends the measurement standby time and issues a measurement start trigger.

[0128] When the measurement start trigger is issued, the impedance measurement unit 13 starts measuring the impedance. The subsequent processing flow is the same as that described as the processing of each unit in the first embodiment.

[0129] However, in the weekend use pattern, the measurement control unit 12 does not perform processing to determine whether an unlocking event has occurred while the impedance measurement unit 13 is measuring the impedance. This is because, during periods when the vehicle V is not in use, the impedance measurement is performed with a sufficient period of time until the next unlocking event occurs. Therefore, the impedance measurement is not interrupted when an unlocking event occurs. Similarly, the measurement of impedance is not postponed because the measurement start waiting time is shorter than the relaxed specified time.

[0130] On the other hand, if the measurement start enable flag is issued and the user unlocks the vehicle V within the measurement implementation period, this is an irregular event in the weekend usage patterns described so far. Therefore, in this case, the impedance measurement is postponed.

[0131] As described above, when a measurement start trigger is issued, impedance measurement is performed by the impedance measurement unit 13. Therefore, the impedance measurement unit 13 is in an OFF (sleep) state until this measurement process is performed, and is turned ON (wakeup) when measurement is performed. However, since the impedance measurement process is performed while the vehicle V is not in use, when the impedance measurement process is completed, the impedance measurement unit 13 returns to the OFF (sleep) state again.

[0132] Furthermore, since each unit of the deterioration estimation device 1 is also in a sleep state, although the impedance measurement has ended, the deterioration state estimation process is not performed following the impedance measurement process by the deterioration state determination unit 14. The deterioration state estimation process by the deterioration state determination unit 14 is performed, for example, after the next weekend arrives, the user performs the unlocking process for the vehicle V, the deterioration estimation device 1 receives the unlocking signal, and the vehicle system starts up, as shown in the explanatory diagram of FIG.

[0133] [Operation] Next, the processing flow of the deterioration estimation device 1 in the above-described weekend usage pattern will be described with reference to Figures 9 and 10. Figures 9 and 10 are flowcharts showing the flow of the method for estimating deterioration of a secondary battery in the second embodiment of the present invention.

[0134] First, as a prerequisite for the deterioration estimation device 1 to start the process of measuring the internal impedance of the secondary battery, it is determined whether the power supply to the vehicle V has been turned off (ST31). This is determined by transmitting a signal indicating whether the power supply to the vehicle V is on or off to the measurement control unit 12. If the measurement control unit 12 does not receive this signal, this means that the power supply to the vehicle V has not been turned off (NO in ST31), and in this case the deterioration estimation device 1 enters a standby state.

[0135] If the measurement control unit 12 receives the signal (YES in ST31), it means that the user has turned off the power to the vehicle V. Therefore, the measurement control unit 12 checks the period of non-use of the vehicle V (ST32). In the case of the weekend use pattern shown in the explanatory diagram of FIG. 8, the weekdays sandwiched between two weekends correspond to the non-use period.

[0136] The measurement control unit 12 sets the timing for starting the measurement waiting time and the measurement standby time based on the confirmed non-use period (ST33). The set timing is transmitted to the timing unit 11, and the timing unit 11 starts timing the measurement waiting time and the measurement standby time in accordance with the set timing (ST34).

[0137] The measurement control unit 12 compares the measurement start waiting time with a preset relaxed specified time. Here, unlike the pattern in which the vehicle V is used every day as described in the first embodiment, the measurement of the impedance is not postponed because the measurement start waiting time is shorter than the relaxed specified time.

[0138] Therefore, the measurement control unit 12 determines whether the measurement start waiting time is equal to or greater than the relaxed specified time (ST35), and if it determines that the measurement start waiting time is less than the relaxed specified time (NO in ST35), it continues processing until the measurement start waiting time exceeds the relaxed specified time.

[0139] On the other hand, if the measurement control unit 12 determines that the measurement start waiting time is equal to or longer than the relaxed specified time (YES in ST35), the measurement control unit 12 issues a measurement start possible flag (ST36). Furthermore, the measurement control unit 12 instructs the timing unit 11 to start timing the measurement implementation period, and the timing unit 11 starts timing the measurement implementation period (ST37).

[0140] While the timing unit 11 is timing the measurement implementation period, the measurement control unit 12 determines whether or not an unlocking event has occurred (ST38). The measurement control unit 12 also determines whether or not a timeout has occurred for the measurement implementation period being measured by the timing unit 11 (ST39). If a timeout has not occurred (NO in ST39), the process returns to step ST38, where the determination of whether or not an unlocking event has occurred and whether or not a timeout has occurred is continued.

[0141] If the measurement control unit 12 determines that the measurement execution period has timed out (YES in ST39), the measurement control unit 12 ends the measurement standby time (ST40 in FIG. 10) and issues a measurement start trigger (ST41).Then, the impedance measurement unit 13 starts measuring the impedance (ST42).

[0142] Thereafter, as described in the first embodiment, the measurement control unit 12 determines whether or not the impedance measurement by the impedance measurement unit 13 has finished (ST43). If the measurement control unit 12 determines that the impedance measurement has not finished (NO in ST43), the impedance measurement by the impedance measurement unit 13 continues.

[0143] On the other hand, if the measurement control unit 12 determines that the impedance measurement by the impedance measurement unit 13 has been completed (YES in ST43), information on the measured impedance is sent from the impedance measurement unit 13 to the deterioration state determination unit 14.

[0144] The measurement control unit 12 determines whether an unlocking event has occurred and whether the vehicle system has been started (ST44, ST45). If an unlocking event has occurred and the vehicle system has been started (YES in ST44, YES in ST45), the degradation state determination unit 14 executes a process to estimate the secondary battery degradation state (ST46). Then, the measurement control unit 12 updates the previous battery state information using the information indicating the secondary battery degradation state estimated by the degradation state determination unit 14 (ST47).

[0145] (Third embodiment) Next, a third embodiment of the present invention will be described. In the third embodiment, the same components as those described in the first or second embodiment are denoted by the same reference numerals, and redundant descriptions of the same components will be omitted.

[0146] The usage pattern of the vehicle V by the user in the third embodiment is a random case in which the vehicle V is used every day but the time at which an unlocking event occurs is not fixed (hereinafter, such a usage pattern will be referred to as a "random usage pattern" as appropriate). Figure 11 is an explanatory diagram illustrating the relationship between the concentration gradient characteristics of lithium ions in a secondary battery and the function of the secondary battery degradation estimation device 1 according to the third embodiment of the present invention.

[0147] The random usage pattern shown in Fig. 11 is based on the pattern in which the user uses the vehicle V every day without performing charging, as described with reference to Fig. 3. Therefore, when the user finishes using the vehicle V and turns off the power of the vehicle V, the gradient of the ion concentration in the secondary battery gradually decreases over time.

[0148] On the other hand, the row below the upper row showing the gradient characteristics of ion concentration shows the frequency distribution of the time of unlocking (activation) by users. As shown in Figure 11, in the case of a random usage pattern, unlocking often occurs after "6:00," but the frequency distribution is generally the same until after "12:00." In other words, in the case of the random usage pattern in the third embodiment, it is completely unknown when in the morning the door will be unlocked.

[0149] This frequency distribution is completely different from the pattern shown in the explanatory diagram of FIG. 3, in which the frequency distribution increases suddenly just before "7:00", peaks at "7:00", and then suddenly decreases again.

[0150] In the case of such a random usage pattern, it is difficult to use the frequency distribution to set a measurement start trigger based on the time when the user most frequently unlocked the vehicle V. Rather, since it is not known when the user will perform the unlocking process for the vehicle V, it is better to start measuring the impedance as soon as the relaxation phenomenon converges in order to ensure time to measure the impedance.

[0151] Therefore, in the third embodiment, the measurement control unit 12 first checks the usage pattern of the vehicle V. That is, for example, the measurement control unit 12 checks the frequency distribution of unlocking (start-up) times of the vehicle V equipped with a secondary battery whose degradation state is to be estimated and which is stored in the storage unit. Then, based on the frequency distribution, the variance value is compared with a preset threshold value.

[0152] If the measurement control unit 12 determines that the variance value is less than the threshold value, it is considered that the frequency distribution is, for example, as described with reference to Figures 3 and 4. In this case, for example, the processing described in the first embodiment is performed.

[0153] On the other hand, if the measurement control unit 12 determines that the variance value is equal to or greater than the threshold, the pattern corresponds to a random usage pattern. Therefore, the measurement control unit 12 instructs the timing unit 11 to start timing the measurement execution time and the measurement waiting time, and determines whether the measurement start waiting time is equal to or greater than the relaxed specified time.

[0154] The timing unit 11 times the measurement start waiting time, and if the measurement control unit 12 determines that the measurement start waiting time is equal to or longer than the relaxed specified time, the measurement control unit 12 issues both a measurement start possible flag and a measurement start trigger.

[0155] That is, in the first and second embodiments, the measurement control unit 12 first issues a measurement start possible flag, and then issues a measurement start trigger so that the measurement is included in the measurement implementation period. That is, although the method for setting the measurement start trigger differs between the usage pattern of the vehicle V in the first embodiment and the usage pattern of the vehicle V in the second embodiment, the measurement start trigger is set after a time has elapsed since the issuance of the measurement start possible flag.

[0156] In contrast, in the case of the usage pattern (random usage pattern) of the vehicle V in the third embodiment, the measurement control unit 12 issues a measurement start trigger at the same time as the measurement start enable flag is issued.

[0157] This is because the timing at which users perform the unlocking process varies, and if the measurement waiting time is set too long, the user may perform the unlocking process at an unknown time, which may result in the impedance measurement being interrupted or postponed.

[0158] Therefore, in order to perform impedance measurement as reliably as possible, the measurement control unit 12 is configured to issue a measurement start trigger immediately when it determines that the measurement start waiting time is equal to or longer than the relaxed specified time, thereby enabling the impedance measurement unit 13 to start measuring impedance earlier.

[0159] 11, the impedance measurement unit 13 starts measuring impedance (turns ON) when a measurement start trigger is issued. Then, when the required measurement time has elapsed, that is, when the impedance measurement is completed, the impedance measurement unit 13 transitions to the OFF state.

[0160] On the other hand, if the information necessary to estimate the degradation state of the secondary battery is acquired by measuring the impedance, the degradation state determination unit 14 may perform the degradation state estimation process after the user unlocks the vehicle V. Therefore, in the explanatory diagram of Figure 11, the degradation state determination unit 14 estimates the degradation state when the measurement control unit 12 receives an unlock signal.

[0161] By issuing a measurement start trigger at such timing, it is possible to increase the possibility of completing the impedance measurement before the time when an unpredictable user unlocks the door.

[0162] [Operation] Next, a flow of the process for estimating the deterioration level of a secondary battery in the third embodiment will be described. Fig. 12 is a flowchart showing the flow of the method for estimating deterioration of a secondary battery in the third embodiment of the present invention.

[0163] The measurement control unit 12 determines whether the user has turned off the vehicle power supply (ST51). This process is the same as the flow in the first and second embodiments described above. If the measurement control unit 12 determines that the vehicle power supply has been turned off (YES in ST51), the measurement control unit 12 then checks the frequency distribution of unlocking (activation) times for the vehicle V (ST52).

[0164] Specifically, the measurement control unit 12 compares the variance of the frequency distribution of unlocking times with a threshold value (ST53). If the variance is equal to or greater than the threshold value (YES in ST53), the measurement control unit 12 instructs the timer unit 11 to start timing the measurement start waiting time and the measurement standby time. Based on this instruction, the timer unit 11 starts timing these times (ST54).

[0165] The measurement control unit 12 then determines whether the measurement start waiting time is equal to or greater than the relaxed specified time (ST55). If the measurement control unit 12 determines that the measurement start waiting time is equal to or greater than the relaxed specified time (YES in ST55), it issues both a measurement start possible flag and a measurement start trigger (ST56). The impedance measurement unit 13 starts measuring the impedance upon the issuance of the measurement start trigger (ST9 in FIG. 6).

[0166] On the other hand, if, as a result of comparing the variance value with the threshold value, the measurement control unit 12 determines that the variance value is less than the threshold value (NO in ST53), the measurement control unit 12 determines whether the measurement start waiting time is equal to or greater than the relaxed specified time (ST4 in Figure 5) in order to perform processing in the flow described above in the first embodiment.

[0167] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the same components as those described in the first to third embodiments are designated by the same reference numerals, and redundant descriptions of the same components will be omitted.

[0168] The usage pattern of the vehicle V in the fourth embodiment is a commercial vehicle. There are various types of commercial vehicles, but here, a case where the vehicle V is a taxi is taken as an example. Figure 13 is an explanatory diagram illustrating the relationship between the concentration gradient characteristics of lithium ions in a secondary battery and the operation of the secondary battery deterioration estimation device 1 according to the fourth embodiment of the present invention.

[0169] The configuration of the explanatory diagram shown in Fig. 13 is generally the same as the explanatory diagrams (Figs. 3, 4, 8, and 11) used to explain the first to third embodiments, except that a section showing "vehicle usage modes" is shown between the upper section showing the ion concentration gradient characteristics and the section explaining the functions of the timer unit.

[0170] As described above, the vehicle V in the fourth embodiment is assumed to be a taxi. Therefore, the usage mode of the vehicle V is a repetition of "rest" and "commercial driving." In the explanatory diagram of FIG. 13 , the period from "0:00" to "8:00" is "rest," and the period from "8:00" to the next "0:00" is "commercial driving."

[0171] Furthermore, when the vehicle V is a taxi, a characteristic of the vehicle is that charging is not only performed when the vehicle is in a "resting" state, but also at any time during commercial operation. This is reflected in the gradient characteristics of the ion concentration.

[0172] That is, when the day's commercial driving ends, the driver turns off the power to the vehicle V and starts charging, causing the gradient of the ion concentration to gradually decrease. The time of the unlocking process for the vehicle V is when the driver performs a pre-work inspection and starts commercial driving, so it basically does not vary from day to day. In this regard, the explanatory diagram in Figure 13 shows that the measurement control unit 12 receives the unlock signal at "8:00."

[0173] Once the driver unlocks the vehicle at 8:00, commercial operation begins. However, the charging process performed while the vehicle V is stopped is often not enough to cover the charge capacity of the secondary battery during commercial operation. Therefore, charging is performed as needed during commercial operation.

[0174] In the explanatory diagram of Figure 13, two valleys appear in the gradient of ion concentration between "8:00" and "0:00". This indicates that the gradient of ion concentration becomes smaller due to the charging process. Therefore, in this case, the charging process is performed twice during commercial operation. Then, although not shown in the figure, the charging process is performed again when the vehicle returns to the depot at "0:00", so the gradient of ion concentration gradually becomes smaller again.

[0175] In the case of commercial vehicles such as taxis, the time that the vehicle V is in a stopped state varies. In the explanatory diagram shown in Fig. 13, it is assumed that it takes eight hours from when the power of the vehicle V is turned off until the measurement control unit 12 receives the unlocking signal, but not all commercial vehicles are stopped for this length of time.

[0176] In other words, in the case of commercial vehicles, it is often difficult to secure sufficient time for the relaxation phenomenon of the secondary battery to converge. On the other hand, appropriate impedance measurement results are required to estimate the deterioration state of the secondary battery.

[0177] Therefore, in order to ensure sufficient time for measuring the impedance while allowing time for the relaxation phenomenon to converge, in the fourth embodiment, the impedance measurement by the impedance measurement unit 13 is performed immediately after the measurement control unit 12 receives the unlocking signal.

[0178] That is, the time when the unlocking event occurs after the power supply of the vehicle V is turned off is roughly the same every day. Therefore, the relaxed specified time is set to the time from when the power supply of the vehicle V is turned off until the next unlocking event occurs. Then, as shown in Fig. 13, when the measurement control unit 12 receives an unlocking signal, it does not issue a measurement start possible flag, but immediately issues a measurement start trigger.

[0179] 13, the gradient of the ion concentration remains small immediately after the measurement control unit 12 receives the unlocking signal. Therefore, by measuring the impedance immediately after the unlocking event occurs, it is possible to perform impedance measurement that obtains the most accurate measurement result possible when the gradient of the ion concentration is small.

[0180] Furthermore, as explained above, the impedance measurement unit 13 does not need to measure the impedance at all of the preset frequency points from the low frequency impedance to the high frequency impedance, but may measure only the low frequency and medium frequency impedance. As mentioned above, the impedance measurement is performed immediately when an unlocking event occurs, but even so, the impedance measurement is not performed while the vehicle V is in the state explained above, but rather before the start of business and while the vehicle is running for business purposes.

[0181] Therefore, for example, only the low- and mid-frequency impedances, which are significantly affected by the relaxation phenomenon, are measured before the start of business. Then, the high-frequency impedance, which is less affected by the relaxation phenomenon, is measured during business operation, for example, during waiting times such as waiting for passengers or during breaks. By measuring at appropriate times depending on the frequency in this way, more accurate impedance measurements can be obtained.

[0182] Furthermore, here, estimation of the deterioration state by the deterioration state determination unit 14 is continued after the impedance measurement is completed. The deterioration state determination unit 14 estimates the deterioration state using the low-frequency and medium-frequency impedances measured immediately before and the high-frequency impedance measured during commercial running before the previous stop.

[0183] This is because, considering that high-frequency impedance measurements are performed during commercial driving as described above, the high-frequency impedance measurement has not yet been performed at the time when the degradation state determination unit 14 estimates the degradation state of the secondary battery, and therefore cannot be used in the estimation process. Therefore, by using the high-frequency impedance value obtained during the previous commercial driving, the degradation state of the secondary battery can be estimated more accurately.

[0184] Furthermore, by adopting this impedance measurement method, it is possible to ensure regular and frequent measurement timing even in the case of commercial vehicles, where secondary batteries deteriorate faster than in private vehicles, and therefore it is possible to continuously obtain impedance values ​​and estimate the progression of deterioration with high accuracy.

[0185] [Operation] Next, a flow of the process for estimating the deterioration level of a secondary battery in the fourth embodiment will be described. Figures 14 and 15 are flowcharts showing the flow of the method for estimating deterioration of a secondary battery in the fourth embodiment of the present invention.

[0186] The measurement control unit 12 determines whether the user has turned off the vehicle power supply (ST61). This process is the same as the flow in the first to third embodiments described above. If the measurement control unit 12 determines that the vehicle power supply has been turned off (YES in ST61), it then determines whether the charging process has started (ST62).

[0187] In the case of commercial vehicles, it is often necessary to perform charging processing while the vehicle is stopped in preparation for the next commercial trip. Therefore, the fourth embodiment is based on the premise that charging processing will be performed.

[0188] When it is determined that the charging process has started (YES in ST62), the measurement control unit 12 sets the specified relaxation time by subtracting the relaxation promotion time due to the charging process (ST63). Thereafter, the measurement control unit 12 determines whether the charging process has ended (ST64). This process is periodically executed until the charging process ends (NO in ST64).

[0189] The measurement control unit 12 then determines whether the user has unlocked the vehicle V, i.e., whether an unlocking signal has been received (ST65). If an unlocking event has not occurred (NO in ST65), the deterioration estimation device 1 remains on standby.

[0190] When an unlocking event occurs, pre-operational tasks such as a pre-operational inspection are performed, and then commercial driving begins. If the measurement control unit 12 determines that an unlocking event has occurred (YES in ST65), it issues a measurement start trigger (ST66). In response to the measurement start trigger being issued, the impedance measurement unit 13 starts measuring the impedance (ST67).

[0191] As described above, the impedance measurement unit 13 measures only the low-frequency impedance and the mid-frequency impedance in this example, and the measurement control unit 12 determines whether the impedance measurement by the impedance measurement unit 13 has been completed (ST68 in FIG. 15).

[0192] If the measurement control unit 12 determines that the impedance measurement has not been completed (NO in ST68), the impedance measurement continues by the impedance measurement unit 13. On the other hand, if the measurement control unit 12 determines that the impedance measurement has been completed (YES in ST68), the process proceeds to the degradation state estimation process.

[0193] Specifically, the degradation state determination unit 14 acquires the impedance value, which is the measurement result, from the impedance measurement unit 13. However, since only the low-frequency impedance and the mid-frequency impedance are measured, information on the high-frequency impedance is missing. Therefore, the degradation state determination unit 14 acquires information on the high-frequency impedance measured before the start of charging, i.e., during the previous commercial driving. Then, the degradation state determination unit 14 performs processing to estimate the degradation state of the secondary battery, taking into account the acquired high-frequency impedance information (ST69).

[0194] The measurement control unit 12 updates the state information of the secondary battery based on the estimation result (ST70). Then, the measurement control unit 12 instructs the impedance measurement unit 13 to measure the high-frequency impedance as appropriate during commercial driving. Based on this instruction, the impedance measurement unit 13 measures the high-frequency impedance (ST71).

[0195] [Effects of the embodiment] (1) A method for estimating deterioration of a secondary battery includes the steps of: setting the timing for starting measurement of the impedance of the secondary battery based on the relaxation phenomenon of the secondary battery, based on the time when the vehicle power supply of the vehicle equipped with the secondary battery to be subjected to deterioration estimation is turned off; measuring the impedance; and estimating the deterioration state of the secondary battery using the measured impedance.

[0196] By adopting such a method for estimating the deterioration of a secondary battery, it is possible to estimate the deterioration state of a secondary battery installed in a vehicle with higher accuracy by taking into account the relaxation phenomenon of the secondary battery whose deterioration state is to be estimated.

[0197] (2) In the method for estimating deterioration of a secondary battery described in (1) above, the step of setting the timing for starting impedance measurement includes a step of timing a measurement start waiting time and a timing waiting time from when the vehicle power supply of the vehicle is turned off, a step of comparing the measurement start waiting time with a predetermined relaxation specified time based on the relaxation phenomenon of the secondary battery, and a step of issuing a measurement start possible flag if it is determined that the measurement start waiting time is equal to or longer than the relaxation specified time, and impedance measurement starts after the measurement start possible flag is issued.

[0198] When setting the specified relaxation time, the relaxation phenomenon of the secondary battery is taken into consideration, so that the impedance can be measured when the secondary battery is in a stable state.

[0199] (3) In the method for estimating deterioration of a secondary battery in (2) above, the step of setting the timing to start measuring impedance further includes the steps of setting a measurement start trigger based on the frequency distribution of the time at which the vehicle user turns off the vehicle power and then unlocks the vehicle again after the measurement start possible flag is issued, issuing the measurement start trigger when the timing standby time has elapsed, and starting impedance measurement when the measurement start trigger is issued.

[0200] By taking into consideration the relaxation phenomenon of the secondary battery when setting the specified relaxation time, it is possible to measure the impedance when the secondary battery is in a stable state, and to complete the impedance measurement before the user performs the unlocking process.

[0201] (4) In the method for estimating deterioration of a secondary battery in (1) above, the step of setting the timing to start measuring the impedance includes the steps of: confirming a period of non-use of the vehicle based on a frequency distribution of the time when the user of the vehicle unlocks the vehicle again after turning off the vehicle power supply; setting a measurement start wait time and a timing to start timing the measurement wait time based on the confirmed period of non-use; comparing the measurement start wait time with a predetermined relaxation specified time based on a relaxation phenomenon of the secondary battery; issuing a measurement start possible flag if it is determined that the measurement start wait time is equal to or longer than the relaxation specified time; starting timing of a predetermined measurement implementation period for issuing a measurement start trigger when the measurement start possible flag is issued; determining whether the user unlocked the vehicle during the measurement implementation period; if it is determined that the user did not unlock the vehicle during the measurement implementation period, further determining whether the measurement implementation period has ended; and issuing a measurement start trigger if it is determined that the measurement implementation period has ended, and

[0202] For example, if a user only uses a vehicle on weekends, there is sufficient time for the secondary battery relaxation phenomenon to converge, but if the time until the impedance measurement starts is long, the possibility that the user will perform the unlocking process increases. Therefore, by setting a timeout for the measurement period, it is possible to ensure that the impedance measurement is completed before the unlocking process is performed.

[0203] (5) In the method for estimating deterioration of a secondary battery in (1) above, the step of setting the timing to start measuring the impedance includes a step of checking the frequency distribution of the time when the user of the vehicle unlocks the vehicle again after turning off the vehicle power supply, a step of comparing a variance value indicating the frequency distribution with a preset threshold value, a step of measuring a measurement start waiting time and a timing waiting time from the time the vehicle power supply of the vehicle is turned off, a step of comparing the measurement start waiting time with a preset relaxation specified time based on the relaxation phenomenon of the secondary battery, and a step of issuing a measurement start possible flag and a measurement start trigger when the variance value is equal to or greater than the threshold value and the measurement start waiting time is determined to be equal to or greater than the relaxation specified time, and a step of starting measurement of the impedance of the secondary battery when the measurement start trigger is issued.

[0204] In the case of such a random usage pattern, it is difficult to predict when the user will perform the unlocking process. Therefore, by issuing a measurement start possible flag and a measurement start trigger together when it is determined that the measurement start wait time is equal to or longer than the relaxed specified time, it is possible to reliably measure impedance even in such a usage pattern.

[0205] (6) In any of the methods for estimating deterioration of a secondary battery described in (1) to (5) above, the step of measuring impedance transitions from measuring impedance at low frequencies to measuring impedance at high frequencies, and the impedance measurement ends before receiving an unlock signal indicating the user's process of unlocking the vehicle.

[0206] When the impedance measuring unit measures the impedance, it measures in order from low frequency to high frequency, so that more time can be spent on measuring the impedance at low frequencies, which takes more time to measure.

[0207] (7) In the method for estimating deterioration of a secondary battery in (6) above, if the impedance measurement is not completed before the unlocking signal is received in the step of measuring the impedance, the impedance measurement is interrupted and a predetermined required frequency is measured at high frequency to measure the impedance.

[0208] If the impedance measurement is interrupted, it is highly likely that the high-frequency impedance measurement will not be performed. However, in such a case, rather than not performing the high-frequency impedance measurement, by measuring only the essential frequencies, the degradation state of the secondary battery can be estimated with higher accuracy.

[0209] (8) In the method for estimating deterioration of a secondary battery in (1) above, the step of setting the timing for starting impedance measurement includes a step of determining whether the charging process has ended after the vehicle power supply is turned off and a charging process for the secondary battery has started, and a step of issuing a measurement start trigger if it is determined that the charging process has ended, and a step of starting measurement of the impedance of the secondary battery when the measurement start trigger is issued.

[0210] For commercial vehicles such as taxis, impedance measurement can be started immediately after the charging process is completed, in accordance with the usage pattern, so that impedance can be measured while the relaxation phenomenon of the secondary battery is as small as possible, even when the vehicle is in commercial operation.

[0211] (9) In the method for estimating deterioration of a secondary battery described in (8) above, the impedance measurement is performed at low and medium frequencies. When a commercial vehicle starts operating, the gradient of the ion concentration in the secondary battery gradually increases. Therefore, by starting with the low-frequency impedance measurement, which takes time to measure, it is possible to obtain the impedance measurement results necessary to estimate the deterioration state of the secondary battery, even if only slightly.

[0212] (10) In the method for estimating deterioration of a secondary battery in (8) or (9) above, the high-frequency impedance is measured while the vehicle is running for business. Because high-frequency impedance can be measured in a short time, the impedance measurement results necessary for estimating the deterioration state of the secondary battery can be obtained by measuring at an appropriate time while the vehicle is running for business.

[0213] (11) In the method for estimating deterioration of a secondary battery in (10) above, after the impedance measurement is completed and the vehicle is unlocked by the user and the vehicle system is started, the method includes a step of adding high-frequency information measured during commercial driving to the measured low-frequency and medium-frequency impedances to estimate the deterioration state of the secondary battery.

[0214] When estimating the deterioration state of a secondary battery in a commercial vehicle, it is possible that measurement of the low-frequency and mid-frequency impedances has been completed, but measurement of the high-frequency impedance has not. In such cases, by using the measurement results of the high-frequency impedance obtained during the previous commercial driving, it is possible to accurately estimate the deterioration state even for a commercial vehicle.

[0215] (12) In the method for estimating deterioration of a secondary battery in any of (2) to (11) above, if a charging process for the secondary battery is started after the vehicle power supply is turned off, the specified relaxation time is set by subtracting the acceleration of the relaxation phenomenon due to the charging process.

[0216] When setting the specified relaxation time, taking into consideration the acceleration of the relaxation phenomenon due to the charging process, it is possible to start measuring the impedance earlier. Therefore, it is possible to ensure a sufficient time for measuring the impedance while taking into consideration the relaxation phenomenon of the secondary battery.

[0217] (13) In the method for estimating deterioration of a secondary battery described in any of (2) to (12) above, when impedance measurement is interrupted, impedance measurement at frequencies other than the required frequencies is not performed, and the most recent measured value is substituted for the impedance value that was not measured.

[0218] When impedance measurement is interrupted, the estimation process for the deterioration state of the secondary battery is not stopped, but is performed using previously acquired measurement results.Even if impedance measurement is not performed once or is incomplete, the estimation process for the deterioration state can be performed, thereby ensuring continuity of the deterioration state.

[0219] (14) A secondary battery deterioration estimation device includes a timing unit that measures the time until the measurement of the impedance of the secondary battery, which is set based on the relaxation phenomenon of the secondary battery, based on the time when the vehicle power supply of the vehicle equipped with the secondary battery that is the subject of deterioration estimation is turned off; an impedance measurement unit that measures the impedance based on a measurement start trigger that is a trigger for starting measurement of the impedance of the secondary battery issued by the timing unit's measurement of the time; and a deterioration state determination unit that uses the measured impedance to estimate the deterioration state of the secondary battery.

[0220] By using such a secondary battery degradation estimation device, when estimating the degradation state of a secondary battery installed in a vehicle, it is possible to estimate the degradation state with higher accuracy by taking into account the relaxation phenomenon of the secondary battery whose degradation state is being estimated.

[0221] (15) The secondary battery deterioration estimation device in (14) above further includes a measurement control unit that controls the timing unit and the impedance measurement unit, wherein the timing unit measures a measurement start waiting time and a timing waiting time from when the vehicle power supply of the vehicle is turned off, and the measurement control unit compares the measurement start waiting time with a predetermined relaxation specified time based on a relaxation phenomenon of the secondary battery, and if it determines that the measurement start waiting time is equal to or longer than the relaxation specified time, issues a measurement start possible flag, and the impedance measurement unit starts measuring the impedance after the measurement start possible flag is issued.

[0222] When setting the specified relaxation time, the relaxation phenomenon of the secondary battery is taken into consideration, so that the impedance can be measured when the secondary battery is in a stable state.

[0223] (16) In the secondary battery deterioration estimation device described in (14) or (15) above, after the measurement start possible flag is issued, the measurement control unit sets a measurement start trigger to start measuring impedance based on the frequency distribution of the time when the vehicle user turns off the vehicle power and then unlocks the vehicle again, and issues the measurement start trigger when the timing standby time has elapsed.

[0224] By taking into consideration the relaxation phenomenon of the secondary battery when setting the specified relaxation time, it is possible to measure the impedance when the secondary battery is in a stable state, and to complete the impedance measurement before the user performs the unlocking process.

[0225] 1... Deterioration estimation device, 11... Timekeeping unit, 12... Measurement control unit, 13... Impedance measurement unit, 14... Deterioration state determination unit, 2... Battery monitoring system, 3... Vehicle control unit, 4... In-vehicle communication unit, A... Antenna, BP... Battery pack, C... Charger, CP... Charging port, CS... Current sensor, I... Inverter, M... Drive motor, V... Vehicle

Claims

a step of setting a timing for starting measurement of the impedance of the secondary battery based on a relaxation phenomenon of the secondary battery, with a time when a vehicle power source of a vehicle equipped with the secondary battery that is the subject of degradation estimation is turned off as a reference; measuring the impedance; estimating a state of deterioration of the secondary battery using the measured impedance; A method for estimating deterioration of a secondary battery, comprising: 　 The step of setting the timing to start measuring the impedance includes: a step of timing a measurement start waiting time and a timing waiting time from when a vehicle power supply of the vehicle is turned off; comparing the measurement start waiting time with a predetermined relaxation time based on a relaxation phenomenon of the secondary battery; issuing a measurement start possible flag when it is determined that the measurement start waiting time is equal to or longer than the relaxed specified time; 2. The method for estimating deterioration of a secondary battery according to claim 1, wherein the impedance measurement is started after the measurement start possible flag is issued. 　 The step of setting the timing to start measuring the impedance further includes: setting a measurement start trigger based on a frequency distribution of times when a user of the vehicle turns off the vehicle power supply and then unlocks the vehicle again after the measurement start enable flag is issued, and issuing the measurement start trigger when the timer standby time has elapsed; starting measurement of the impedance when the measurement start trigger is issued; 3. The method for estimating deterioration of a secondary battery according to claim 2, further comprising: 　 The step of setting the timing to start measuring the impedance includes: confirming a period of non-use of the vehicle based on a frequency distribution of times when a user of the vehicle turns off the vehicle power source and then unlocks the vehicle again; setting the measurement start waiting time and the timing to start counting the measurement standby time based on the confirmed non-use period; comparing the measurement start waiting time with a predetermined relaxation time based on a relaxation phenomenon of the secondary battery; issuing a measurement start possible flag when it is determined that the measurement start waiting time is equal to or longer than the relaxed specified time; a step of starting time measurement of a preset measurement implementation period for issuing a measurement start trigger when the measurement start possible flag is issued; a step of determining whether or not the user has unlocked the door during the measurement period; When it is determined that the user has not unlocked the door during the measurement period, a step of determining whether the measurement period has ended or not; issuing the measurement start trigger when it is determined that the measurement implementation period has ended; a step of starting measurement of the impedance of the secondary battery when the measurement start trigger is issued; 2. The method for estimating deterioration of a secondary battery according to claim 1, further comprising: 　 The step of setting the timing to start measuring the impedance includes: A step of checking a frequency distribution of times when a user of the vehicle turns off the vehicle power supply and then unlocks the vehicle again; comparing a variance value indicating the frequency distribution with a preset threshold value; a step of timing a measurement start waiting time and a timing waiting time from when a vehicle power supply of the vehicle is turned off; comparing the measurement start waiting time with a predetermined relaxation time based on a relaxation phenomenon of the secondary battery; and issuing a measurement start enable flag and a measurement start trigger when the variance value is equal to or greater than the threshold value and when it is determined that the measurement start waiting time is equal to or greater than the relaxed specified time, a step of starting measurement of the impedance of the secondary battery when the measurement start trigger is issued; 2. The method for estimating deterioration of a secondary battery according to claim 1, further comprising:

2. The method for estimating deterioration of a secondary battery according to claim 1, wherein the step of measuring the impedance transitions from measuring the impedance at a low frequency to measuring the impedance at a high frequency, and the measurement of the impedance is terminated before receiving an unlock signal indicating an unlocking process of the vehicle by a user.

7. The method for estimating deterioration of a secondary battery according to claim 6, wherein, in the step of measuring the impedance, if the measurement of the impedance is not completed before the unlocking signal is received, the measurement of the impedance is interrupted and the impedance is measured by measuring a predetermined essential frequency at a high frequency. 　 The step of setting the timing to start measuring the impedance includes: a step of determining whether the charging process has ended after the vehicle power source is turned off and a charging process for the secondary battery is started; issuing a measurement start trigger when it is determined that the charging process has ended; a step of starting measurement of the impedance of the secondary battery when the measurement start trigger is issued; 2. The method for estimating deterioration of a secondary battery according to claim 1, further comprising:

9. The method for estimating deterioration of a secondary battery according to claim 8, wherein the impedance is measured at a low frequency and a medium frequency.

10. The system for estimating deterioration of a secondary battery according to claim 9, wherein the measurement of the high frequency impedance is carried out while the vehicle is running for business.

11. The method for estimating deterioration of a secondary battery according to claim 10, further comprising a step of adding the high-frequency information measured during the commercial driving to the measured impedance at the low frequency and the medium frequency after the impedance measurement has been completed and the vehicle system has been started up by the user, to estimate the deterioration state of the secondary battery. 　 The method for estimating deterioration of a secondary battery according to claim 2, characterized in that, when a charging process for the secondary battery is started after the vehicle power source is turned off, the specified relaxation time is set by subtracting the amount of acceleration of the relaxation phenomenon due to the charging process.

3. The method for estimating deterioration of a secondary battery according to claim 2, characterized in that, when the measurement of the impedance is interrupted, the measurement of the impedance at frequencies other than the required frequency is not performed, and the value of the impedance that was not measured is substituted with the most recently measured value. 　 a timer that measures a time from when a vehicle power source of a vehicle equipped with a secondary battery that is the subject of degradation estimation is turned off to when measurement of the impedance of the secondary battery, which is set based on a relaxation phenomenon of the secondary battery, begins; an impedance measurement unit that measures the impedance based on a measurement start trigger that is a trigger for starting measurement of the impedance of the secondary battery and is issued by the time measurement unit; a degradation state determination unit that estimates a degradation state of the secondary battery using the measured impedance; A secondary battery deterioration estimation device comprising: 　 a measurement control unit that controls the timing unit and the impedance measurement unit; the timing unit measures a measurement start waiting time and a timing standby time from when a vehicle power supply of the vehicle is turned off, the measurement control unit compares the measurement start waiting time with a predetermined relaxation time based on a relaxation phenomenon of the secondary battery, and issues a measurement start enable flag when determining that the measurement start waiting time is equal to or greater than the relaxation time; 15. The secondary battery deterioration estimation device according to claim 14, wherein the impedance measurement unit starts measuring the impedance after the measurement start enable flag is issued. 　 The secondary battery deterioration estimation device described in claim 15, characterized in that after the measurement start possible flag is issued, the measurement control unit sets a measurement start trigger to start measuring the impedance based on a frequency distribution of the time at which the user of the vehicle turns off the vehicle power supply and then unlocks it again, and issues the measurement start trigger when the timing standby time has elapsed.

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