Battery diagnostic device and program

Abstract

To suitably calculate SOH for each unit cell included in an assembled battery.SOLUTION: A battery system 10 comprises: an assembled battery 20 that includes a plurality of unit cells 21 connected in series; and sensors 25 and 26 that are provided on at least one of the unit cells 21 and detect a parameter for deterioration diagnosis. A BMU 30 includes: a first calculation section that acquires the parameter detected by the detection section for the unit cell 21 and calculates SOH on the basis of the parameter; a second calculation section that calculates an amount of change in the SOC caused by energization for the plurality of unit cells 21; and a third calculation section that calculates, when the unit cell 21 for which the first calculation section has calculated the SOH is a first unit cell 21A and the unit cell 21 for which the SOH has not been calculated is a second unit cell 21A, a value obtained by multiplying a change amount ratio, which is a ratio of an amount of change in the SOC of the first unit cell 21A to an amount of change in the SOC of a second unit cell 21B, by the SOH of the first unit cell 21A, as the SOH of the second unit cell 21B.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a battery diagnostic device and a program.

Background Art

[0002] In a storage battery, the full charge capacity decreases as it deteriorates. Therefore, a technique for calculating SOH (State Of Health) as a deterioration index indicating the degree of deterioration of the storage battery is known. Conventionally, a temperature sensor for detecting the battery temperature and a sensor for detecting the impedance (internal resistance) of a secondary battery are provided in the secondary battery, and a technique for estimating the capacity of the secondary battery based on the battery temperature and impedance has been disclosed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a battery pack having a plurality of single cells, in order to calculate the SOH of each single cell, it is necessary to detect the temperature and impedance for each single cell. However, when sensors for detecting temperature and impedance are provided for all single cells, there are concerns about cost increase and increase in size.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a battery diagnostic device and a program capable of suitably calculating the SOH for each single cell included in a battery pack.

Means for Solving the Problems

[0006] In order to solve the above problems, the present invention A battery diagnostic device is applied to a battery system comprising a battery pack in which multiple single cells are connected in series, and a detection unit provided in at least one of the multiple single cells for detecting parameters for degradation diagnosis, and calculates the State of Health (SOH) which indicates the degree of degradation of each single cell, A first calculation unit that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation unit calculates the amount of change in SOC caused by energizing the aforementioned plurality of single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation unit is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, the third calculation unit calculates the value obtained by multiplying the change ratio, which is the ratio of the change in SOC of the first single cell to the change in SOC of the second single cell, by the SOH of the first single cell, and this value is designated as the SOH of the second single cell. It is characterized by being equipped with [the following features].

[0007] In a battery pack, the change in the remaining capacity of each cell due to energization corresponds to the product of the change in the cell's SOH and SOC (State of Charge) and its reference full charge capacity. In this case, in a battery pack where multiple cells are connected in series, even if the SOH of each cell differs, the change in the remaining capacity of each cell will be the same, and therefore the product of the change in SOH and the change in SOC will be the same for each cell. In view of this, among the multiple cells, the cell for which the SOH has been calculated based on degradation diagnostic parameters was designated as the first cell, and the cell for which the SOH has not been calculated was designated as the second cell. Then, the SOH of the second cell was calculated by multiplying the change ratio, which is the ratio of the change in SOC of the first cell to the change in SOC of the second cell, by the SOH of the first cell. This makes it possible to calculate the SOH for all cells even if the degradation diagnostic parameters have not been obtained for all cells. As a result, the SOH can be suitably calculated for each cell included in the battery pack. [Brief explanation of the drawing]

[0008] [Figure 1] A diagram showing the configuration of the battery system. [Figure 2] A diagram showing the correlation map used to calculate SOH. [Figure 3] A diagram showing the voltage-state-of-octane (SOC) characteristics of a single cell. [Figure 4] A flowchart showing the procedure for calculating the State of Health (SOH) of a single cell. [Figure 5] A diagram showing a modified configuration of the battery system. [Figure 6] A diagram showing a modified configuration of the battery system. [Figure 7] A diagram showing the configuration of the battery system in the second embodiment. [Figure 8] A flowchart showing the SOH calculation process in the second embodiment. [Figure 9] A flowchart illustrating the SOH calculation process in the third embodiment. [Figure 10] A diagram showing the voltage-state-of-octane (SOC) characteristic curve of a single cell. [Figure 11] A diagram showing the configuration of a battery system in another embodiment. [Modes for carrying out the invention]

[0009] (First Embodiment) The first embodiment will be described below with reference to the drawings. In this embodiment, a battery system 10 installed in an electric vehicle such as a hybrid vehicle or an electric vehicle will be described. Figure 1 is a diagram showing the configuration of the battery system 10.

[0010] In Figure 1, the battery system 10 includes a battery pack 20 and a BMU 30 (Battery Management Unit) which serves as a monitoring device for the battery pack 20. The battery pack 20 is composed of multiple individual cells 21 connected in series. Each individual cell 21 is, for example, a lithium-ion battery. Each individual cell 21 may be composed of multiple battery cells, for example, multiple battery cells may be connected in series or in parallel. The battery pack 20 has n individual cells 21, and in Figure 1, each individual cell 21 is numbered 1, 2, ..., n-2, n-1, n in order from the negative electrode side of the battery pack 20. Each individual cell 21 has the same configuration, and each individual cell 21 has the same rated capacity.

[0011] A current sensor 23 is provided in the electrical path 22 in which each individual cell 21 is connected in series. Furthermore, a voltage sensor 24 is provided in the battery pack 20 to detect the voltage across each individual cell 21. The voltage sensor 24 monitors the terminal voltage of all individual cells 21.

[0012] In a set of n individual cells 21, a specific cell 21 is equipped with a temperature sensor 25 for detecting the cell temperature and an impedance sensor 26 for detecting the impedance as internal resistance. The impedance detection method in the impedance sensor 26 can be arbitrary, but for example, it is preferable to calculate the impedance from the voltage response when an alternating current is applied to the cell 21. The impedance may be calculated at multiple frequencies.

[0013] In the following description, to distinguish between a single cell 21 equipped with a temperature sensor 25 and an impedance sensor 26 (sensor-equipped single cell 21) and a single cell 21 without these sensors 25 and 26 (sensor-less single cell 21), the sensor-equipped single cell 21 will also be referred to as "first single cell 21A" and the sensor-less single cell 21 as "second single cell 21B". In the drawings, to avoid complexity, only the reference numeral 21A is used for the single cell 21, and among the multiple single cell 21s, the single cell 21 without the reference numeral 21A corresponds to the second single cell 21B.

[0014] In this embodiment, among the n single cells 21, the single cell 21 that reaches the highest temperature during energization (charging or discharging) of the battery pack 20 is defined as the first single cell 21A. For the first single cell 21A, temperature detection by the temperature sensor 25 and impedance detection by the impedance sensor 26 are performed.

[0015] Supplementary note: Among the n single cells 21, during energization of the battery pack 20, a relative temperature difference occurs according to the arrangement structure in the battery case and the positional relationship with the cooling device. For example, when each single cell 21 is arranged side by side, it is considered that the temperature of the single cell 21 is relatively high near the center of the arrangement, and the temperature of the single cell 21 is relatively low near the ends of the arrangement. In this embodiment, among the n single cells 21 shown in FIG. 1, it is assumed that the (n - 2)-th single cell 21 is the single cell that reaches the highest temperature under the energized state, and the (n - 2)-th single cell 21 is defined as the first single cell 21A, and the single cells 21 other than the (n - 2)-th are defined as the second single cells 21B.

[0016] Note that the first single cell 21A only needs to be determined from the high-temperature cells that are relatively high-temperature among the single cells 21 under the energized state of the battery pack 20. For example, it may be a single cell that is high-temperature with respect to the average temperature of all the single cells 21.

[0017] The BMU30 is an electronic control unit having a microcomputer with a CPU and various memories, and the detection signals from the various sensors mentioned above are input to the BMU30 as appropriate. Based on the program stored in the memory, the BMU30 performs various calculations related to the battery pack 20. Specifically, the BMU30 calculates the State of Charge (SOC) as an index indicating the charge storage state of each cell 21 based on the terminal voltage of each cell 21. The BMU30 also calculates the State of Health (SOH) as an index indicating the degradation state of each cell 21 based on the battery temperature and impedance of each cell 21. SOH corresponds to a degradation index indicating the degree of degradation of each cell 21. In this embodiment, the BMU30 corresponds to a "battery diagnostic device," and the temperature sensor 25 and impedance sensor 26 correspond to a "detection unit" that detects parameters for diagnosing the degradation of the cell 21.

[0018] The following describes in detail the configuration for calculating the State of Health (SOH) of each individual cell 21.

[0019] In the battery system 10 of this embodiment, a temperature sensor 25 and an impedance sensor 26 are provided only on a specific cell 21 (first cell 21A) among the multiple cell 21s. In other words, it is possible to acquire degradation diagnostic parameters using only the first cell 21A, and to calculate the State of Health (SOH) based on those diagnostic parameters. To put it another way, it is not possible to calculate the SOH based on the diagnostic parameters (battery temperature, impedance) for the second cell 21B other than the first cell 21A. However, in the battery pack 20, the amount of change in the remaining capacity of each cell 21 caused by energization corresponds to the product of the SOH, the change in SOC, and the reference fully charged capacity of the cell 21. In this case, in the battery pack 20 in which multiple cell 21s are connected in series, even if the SOH of each cell 21 is different, the amount of change in the remaining capacity of each cell 21 will be the same, so the product of the SOH and the change in SOC will be the same for each cell 21. In light of this, in this embodiment, the SOH of the second cell 21B is calculated based on the ratio of the change in SOC (ΔSOC) of the first cell 21A and the second cell 21B, respectively.

[0020] In other words, the SOC[%] and SOH[%] of each cell 21 are expressed by the following equations (Equation 1) and (Equation 2). Note that Cr is the remaining capacity [Ah] of cell 21, Cf is the actual full charge capacity [Ah] of cell 21, and Cf0 is the reference full charge capacity [Ah] of cell 21. SOC=Cr / Cf…(Formula 1) SOH=Cf / Cf0…(Formula 2) Furthermore, if the remaining capacity Cr of the single cell 21 changes due to the application of power, the change in remaining capacity ΔCr is expressed by the following (Equation 3). ΔCr = ΔSOC × Cf =ΔSOC×(SOH×Cf0)…(Formula 3) In this case, the change in remaining capacity ΔCr is the same regardless of the SOH of each cell 21, so when comparing the first cell 21A and the second cell 21B, their respective "ΔSOC × SOH" values ​​are the same.

[0021] Furthermore, if we let SOH be "SOH1" and ΔSOC be "ΔSOC1" for the first cell 21A, and SOH be "SOH2" and ΔSOC be "ΔSOC2" for the second cell 21B, then "ΔSOC1 × SOH1 = ΔSOC2 × SOH2" holds true, and the following equation (4) is obtained. SOH2=SOH1×(ΔSOC1 / ΔSOC2) …(Formula 4) In this embodiment, the SOH2 of the second cell 21B is calculated using (Equation 4). In this case, the SOH2 of the second cell 21B is calculated by referring to the ΔSOC1 and SOH1 of the first cell 21A. That is, according to (Equation 4), the SOH2 of the second cell 21B is calculated by multiplying the change ratio, which is the ratio of the change in SOC of the first cell 21A (ΔSOC1) to the change in SOC of the second cell 21B (ΔSOC2), by the SOH1 of the first cell 21A.

[0022] As shown in Figure 1, the BMU 30 has a configuration for calculating SOH, which includes a first SOH calculation unit 31, an SOC calculation unit 32, a ΔSOC calculation unit 33, and a second SOH calculation unit 34.

[0023] The first SOH calculation unit 31 acquires the battery temperature and impedance of the first cell 21A, and calculates the SOH1 of the first cell 21A based on the battery temperature and impedance. In this case, it is preferable to calculate SOH1 using a correlation map that shows the correlation between battery temperature, impedance and SOH. An example of a correlation map is shown in Figure 2. In the correlation map, the SOH value should be determined by suitability, etc. However, instead of a correlation map, it is also possible to calculate SOH1 using a correlation formula that defines the relationship between battery temperature, impedance and SOH.

[0024] The SOC calculation unit 32 acquires the terminal voltage for each individual cell 21 and calculates the SOC based on that terminal voltage. In this case, the SOC calculation unit 32 may use the voltage-SOC characteristics shown in Figure 3 to calculate the SOC of each individual cell 21. The voltage acquired as the terminal voltage may be the OCV (Open Circuit Voltage) when the individual cell 21 is not energized. The OCV may be the voltage after a time has elapsed for state stabilization after the energization of each individual cell 21 has ended. For example, the OCV of each individual cell 21 may be acquired at a time after a predetermined period of time has elapsed since the vehicle's power switch was turned off. Alternatively, the OCV of each individual cell 21 may be acquired before the vehicle's power switch is turned on, for example, at a time such as when the vehicle door is opened.

[0025] The ΔSOC calculation unit 33 calculates ΔSOC for each individual cell 21, based on the SOC of each individual cell 21 calculated by the SOC calculation unit 32. ΔSOC represents the change in SOC caused by the energization of the battery pack 20. For example, ΔSOC may be calculated as the difference between the SOC calculated at the end of the current vehicle run and the SOC calculated at the end of previous vehicle runs.

[0026] The second SOH calculation unit 34 uses the above (Equation 4) to calculate the SOH2 of the second cell 21B based on the SOH1 of the first cell 21A calculated by the first SOH calculation unit 31 and the ΔSOC of each cell 21 calculated by the ΔSOC calculation unit 33. As a result, the value obtained by multiplying the ΔSOC ratio, which is the ratio of the ΔSOC1 of the first cell 21A to the ΔSOC2 of the second cell 21B, by the SOH1 of the first cell 21A is calculated as the SOH2 of the second cell 21B.

[0027] The first SOH calculation unit 31 corresponds to the "first calculation unit," the SOC calculation unit 32 and the ΔSOC calculation unit 33 correspond to the "second calculation unit," and the second SOH calculation unit 34 corresponds to the "third calculation unit."

[0028] Figure 4 is a flowchart showing the procedure for calculating the State of Health (SOH) of each individual cell 21. This process is performed by the BMU 30, for example, after the vehicle's power switch is turned off.

[0029] In Figure 4, in step S11, the battery temperature and impedance of the first cell 21A (cell 21, the (n-2)th cell), which is a high-temperature battery, are acquired as diagnostic parameters to be used for degradation diagnosis. In step S12, the SOH1 of the first cell 21A is calculated based on the diagnostic parameters, for example, using the correlation map in Figure 2. The timing of the SOH1 calculation may be any timing while the power switch is ON, as long as the diagnostic parameters can be acquired.

[0030] Subsequently, in step S13, the terminal voltage (OCV) of all individual cells 21 is acquired, and in the following step S14, the State of Emergency (SOC) is calculated for each individual cell 21 based on its terminal voltage, using, for example, the voltage-SOC characteristics shown in Figure 3. The SOC calculated for each individual cell 21 is preferably stored in backup memory after each vehicle trip. In step S15, for each individual cell 21, the difference between the SOC calculated at the end of the current vehicle run and the SOC calculated at the end of the previous vehicle run is calculated as ΔSOC.

[0031] In step S16, it is determined whether the ΔSOC calculated in step S15 is greater than or equal to a predetermined threshold TH1. If ΔSOC is greater than or equal to the threshold TH1, the process proceeds to the subsequent step S17; if ΔSOC is less than the threshold TH1, the process ends there. In step S16, it may be determined whether the ΔSOC of a specific cell 21 that has been predetermined is greater than or equal to the threshold TH1, or it may be determined whether the smallest SOC or the largest SOC among all cell 21 is greater than or equal to the threshold TH1 (the same applies to step S17 described later).

[0032] Furthermore, if ΔSOC, which is the difference between the current value of SOC and the previous value of SOC, is less than the threshold TH1, it is also possible to return to step S15, calculate the difference between the current value of SOC and previous values ​​of SOC (for example, the value from two or three times ago) as ΔSOC, and then determine again in step S16 whether ΔSOC is greater than or equal to the threshold TH1.

[0033] In step S17, it is determined whether ΔSOC is less than a predetermined threshold TH2. Threshold TH2 is a value greater than threshold TH1. If ΔSOC is less than threshold TH2, the process proceeds to step S18; if ΔSOC is greater than or equal to threshold TH2, the process proceeds to step S19.

[0034] In step S18, using the above (Equation 4), the SOH2 of the second cell 21B is calculated based on the SOH1 of the first cell 21A calculated in step S12 and the ΔSOC of each cell 21 calculated in step S15.

[0035] In step S19, the SOH of each cell 21 is calculated using (Equation 5) below, based on the ΔSOC of each cell 21 calculated in step S15 and the integrated current value from the time of the previous SOC calculation to the time of the current SOC calculation used to calculate the ΔSOC. SOH = Sum of Current / ΔSOC …(Equation 5) In step S19, instead of calculating the SOH of all single cells 21 using (Equation 5), only the SOH2 of the second single cell 21B may be calculated using (Equation 5). The integrated current value is calculated by integrating the energizing current for each single cell 21 in a current integration process (not shown) and is sequentially stored in backup memory. In (Equation 5), the integrated current value in the numerator of the right-hand side can be the current capacity, and ΔSOC in the denominator of the right-hand side can be "ΔSOC × full charge capacity".

[0036] If step S17 is NO, it is possible to terminate without calculating the SOH2 of the second cell 21B. In Figure 4, steps S11 and S12 correspond to the "first calculation process," steps S14 and S15 correspond to the "second calculation process," and step S18 corresponds to the "third calculation process."

[0037] According to the embodiment described in detail above, the following excellent effects can be obtained.

[0038] Among the multiple single cells 21, the single cell 21 for which SOH was calculated based on degradation diagnostic parameters was designated as the first single cell 21A, and the single cell 21 for which SOH had not been calculated was designated as the second single cell 21B. Then, the SOH2 of the second single cell 21B was calculated by multiplying the ΔSOC ratio (change rate), which is the ratio of ΔSOC1 of the first single cell 21A to ΔSOC2 of the second single cell 21B, by the SOH1 of the first single cell 21A. This makes it possible to calculate SOH for all single cells 21 even if degradation diagnostic parameters have not been obtained for all of them. As a result, the SOH can be suitably calculated for each single cell 21 included in the battery pack 20.

[0039] Among multiple single cells 21, the high-temperature cell is relatively prone to degradation and is highly sensitive to degradation. Furthermore, in a battery pack 20 in which multiple single cells 21 are connected in series, the performance of the battery pack 20 is limited by the single cell 21 with the greatest degree of degradation. Focusing on this point, the high-temperature cell is designated as the first single cell 21A, and the SOH2 of the second single cell 21B is calculated based on the ΔSOC ratio (ΔSOC1 / ΔSOC2) of the first single cell 21A (high-temperature cell) and the second single cell 21B, and the SOH1 of the first single cell 21A. This allows for highly accurate degradation diagnosis of the second single cell 21B, using the single cell presumed to have the greatest degree of degradation as a reference. In addition, since the IR drop (voltage drop due to path resistance), which is an error factor, is small in the high-temperature cell, an improvement in the accuracy of SOH can also be expected.

[0040] When the ΔSOC of a single cell 21 is greater than a predetermined value, instead of calculating the SOH2 of the second single cell 21B using the ΔSOC1 and SOH1 of the first single cell 21A (calculation of SOH2 by (Equation 4)), the SOH of each single cell 21 is calculated based on ΔSOC and the integrated current value (calculation of SOH by (Equation 5)). This makes it possible to properly calculate the SOH of each single cell 21 regardless of the magnitude of ΔSOC (SOC change).

[0041] As a variation of this first embodiment, the following configuration is also possible.

[0042] Figure 5 is a diagram of the battery system 10 in this modified example. In Figure 5, unlike Figure 1, the first cell 21A is defined as the cell 21 that is the coldest among the n individual cells 21 when the battery pack 20 is energized (charging or discharging). The first cell 21A is configured to have temperature detection by a temperature sensor 25 and impedance detection by an impedance sensor 26. Specifically, among the n individual cells 21 shown in Figure 5, the nth cell 21 is defined as the cell 21 that is the coldest under the energized state of the battery pack 20. This nth cell 21 is defined as the first cell 21A, and the other cell 21s are defined as the second cell 21B. Note that the first cell 21A can be any cell 21 that is relatively cold among the individual cells 21 under the energized state of the battery pack 20, for example, any cell 21 that is colder than the average temperature of all the individual cells 21.

[0043] The procedure for calculating the SOH of each cell 21 using the BMU30 is generally as shown in Figure 4 above. Briefly speaking, in Figure 4, in steps S11 and S12, the cell temperature and impedance of the first cell 21A (the nth cell 21), which is a low-temperature cell, are obtained, and SOH1 is calculated. Then, in step S18, the SOH2 of the second cell 21B (a cell 21 other than the nth cell) is calculated based on the SOH1 of the first cell 21A (the nth cell 21) and the ΔSOC of each cell 21 using (Equation 4) above.

[0044] Among the multiple single cells 21, the low-temperature cell has a higher impedance than the high-temperature cell, allowing for relatively high-precision detection of impedance, a parameter for degradation diagnosis. Focusing on this point, the low-temperature cell is designated as the first single cell 21A, and the SOH2 of the second single cell 21B is calculated based on the ΔSOC ratio (ΔSOC1 / ΔSOC2) of the first single cell 21A (low-temperature cell) and the second single cell 21B, and the SOH1 of the first single cell 21A. This allows for accurate calculation of the SOH1 of the first single cell 21A, and consequently, high-precision degradation diagnosis of the second single cell 21B.

[0045] As shown in Figure 6, each individual cell 21 of the battery pack 20 may be divided into several battery groups G1 to Gn with relatively different temperatures under energized conditions, and a specific individual cell 21X that enables parameter detection by the temperature sensor 25 and impedance sensor 26 may be defined for each battery group G1 to Gn. The specific individual cell 21X may be a high-temperature cell that is relatively hot, or a low-temperature cell that is relatively cold, and can be defined for each battery group G1 to Gn. The number of individual cells 21 in each battery group G1 to Gn may be the same or different. For example, in each battery group G1 to Gn, a battery group with a large temperature difference between the highest-temperature individual cell 21 and the lowest-temperature individual cell 21 may have fewer individual cells 21 than a battery group with a small temperature difference.

[0046] The BMU30 should perform the SOH calculation process shown in Figure 4 above, treating a specific single cell 21X as the first single cell 21A for each battery group G1 to Gn. In this case, the BMU30 calculates the SOH1 of the first single cell 21A (specific single cell 21X) for each battery group G1 to Gn based on the degradation diagnosis parameters detected in the first single cell 21A, and then uses that SOH1 to calculate the SOH2 of the second single cell 21B.

[0047] The following describes other embodiments, focusing on the differences from the first embodiment described above.

[0048] (Second Embodiment) Figure 7 is a diagram showing the configuration of the battery system 10 in this embodiment. In Figure 7, as a difference from Figure 1, among the n individual cells 21, the cell 21 that becomes the hottest and the cell 21 that becomes the coldest when the battery pack 20 is energized are designated as the first cell 21A, and the temperature detection by the temperature sensor 25 and the impedance detection by the impedance sensor 26 are performed for these two first cell 21A. Specifically, when the battery pack 20 is energized, the (n-2) cell 21 is the hottest cell, and the (n) cell 21 is the coldest cell. These (n-2) and (n) cell 21 are designated as the first cell 21A, and the cell 21 other than (n-2) and (n) are designated as the second cell 21B. Note that the hot and cold cells can be any cells that are relatively hot and relatively cold when the battery pack 20 is energized.

[0049] In this embodiment, for each second cell 21B, a first cell 21A with a small temperature difference under energized conditions of the battery pack 20 is combined with it, and the SOH2 of the second cell 21B is calculated using the ΔSOC1 and SOH1 of the combined first cell 21A. It is preferable that for each second cell 21B (cells 21 other than n-2 and n), it is predetermined whether to combine it with the lower temperature first cell 21A or the higher temperature first cell 21A.

[0050] Furthermore, in this embodiment, the method for calculating the SOH2 of the second cell 21B is changed depending on whether the battery pack temperature Tb, which is the overall temperature of the battery pack 20, is lower or higher than a predetermined temperature. Specifically, if the battery pack temperature Tb is lower than the predetermined temperature, the low-temperature cell is designated as the first cell 21A, and the SOH2 of the second cell 21B is calculated based on the SOH1 of the first cell 21A. On the other hand, if the battery pack temperature Tb is higher than the predetermined temperature, for each second cell 21B, the first cell 21A with the smaller temperature difference between the low-temperature first cell 21A and the high-temperature first cell 21A is combined, and the SOH2 of the second cell 21B is calculated based on the SOH1 of that first cell 21A.

[0051] The battery pack temperature Tb may be determined using the value detected by a temperature sensor 25 installed in any of the n individual cells 21, or, assuming that the temperature of the battery pack 20 has sufficiently decreased after use, the value detected by an ambient temperature sensor may be used.

[0052] Figure 8 is a flowchart of the SOH calculation process in this embodiment. This process is performed by the BMU30, replacing the process in Figure 4. In Figure 8, the same steps as in Figure 4 are given the same step numbers and detailed explanations are omitted.

[0053] In Figure 8, in steps S11 and S12, the battery temperature and impedance are obtained as parameters used for degradation diagnosis for the two first single cells 21A, and SOH1 is calculated based on these diagnostic parameters. At this time, SOH1 is calculated for both the first single cell 21A which is a high-temperature battery and the first single cell 21A which is a low-temperature battery. Subsequently, in steps S13 to S15, the SOC is calculated for each single cell 21 based on the terminal voltage (OCV), and the difference between the SOC at the end of the current vehicle run and the SOC at the end of the previous vehicle run is calculated as ΔSOC. Then, in step S16, if it is determined that ΔSOC is greater than or equal to the threshold TH1, and in step S17, if it is determined that ΔSOC is less than the threshold TH2, the process proceeds to step S21.

[0054] In step S21, it is determined whether the battery pack temperature Tb is lower than a predetermined temperature threshold KT. The temperature threshold KT is, for example, 0°C. If it is determined that the battery pack temperature Tb is lower than the temperature threshold KT, the process proceeds to step S22, where the first single cell 21A, which is the low-temperature cell (the nth single cell 21) of the two first single cells 21A, is determined to be the first single cell 21A that references SOH1. If it is determined that the battery pack temperature Tb is higher than the temperature threshold KT, the process proceeds to step S23, where for each second single cell 21B, the first single cell 21A with the smaller temperature difference between it and the second single cell 21B (the low-temperature cell (the nth single cell 21) and the high-temperature cell (the n-2th single cell 21)) is determined to be the first single cell 21A that references SOH1.

[0055] Subsequently, in step S18, the ΔSOC and SOH1 of the first cell 21A determined in steps S21 to S23 are referenced, and the SOH2 of the second cell 21B is calculated using (Equation 4) above.

[0056] The effects of the second embodiment, which have been described in detail above, are described below.

[0057] Since the voltage-SOC characteristics of the battery pack 20 are temperature-dependent, if the individual cells 21 have similar temperatures under the energized state of the battery pack 20, their voltage-SOC characteristics will be similar. In this case, if the first cell 21A and the second cell 21B are combined using individual cells 21 with small temperature differences, the SOC errors occurring in each of these cells 21A and 21B will be equivalent, and the same error will be applied to both the numerator and denominator of the ΔSOC ratio in (Equation 4) above. Therefore, the ΔSOC ratio will be less affected by temperature. Taking this into consideration, for each second cell 21B, the SOH2 of the second cell 21B is calculated using the ΔSOC1 and SOH1 of the first cell 21A that has the smallest temperature difference with the second cell 21B under the energized state of the battery pack 20. This ensures accuracy in calculating SOH even if there is a large temperature difference between each individual cell 21 in the entire battery pack 20, and allows for the proper calculation of SOH for all individual cells 21.

[0058] When the battery pack 20 is in a low-temperature state, the lower-temperature cell 21 among the multiple cell 21 will have higher impedance detection accuracy, and the calculation accuracy of SOH1 for the first cell 21A will be higher. On the other hand, when the battery pack 20 is not in a low-temperature state, the advantage of using a low-temperature cell as a reference decreases. Taking this into consideration, when the battery pack temperature Tb is determined to be lower than the temperature threshold KT (predetermined temperature), the low-temperature cell is designated as the first cell 21A, and the SOH2 of the second cell 21B is calculated based on the SOH1 of the first cell 21A. Conversely, when the battery pack temperature Tb is determined to be higher than the temperature threshold KT, the SOH2 of the second cell 21B is calculated using the ΔSOC1 and SOH1 of the first cell 21A, which has a small temperature difference with the second cell 21B. As a result, the SOH of each cell 21 can be appropriately calculated whether the battery pack 20 is in a low-temperature state or not.

[0059] As a variation of this second embodiment, the following configuration is also possible.

[0060] It is also possible to designate three or more of the n single cells 21, each having a different battery temperature when the battery pack 20 is energized, as the first single cell 21A. For example, if three single cells 21 are designated as the first single cell 21A, the SOH2 of the second single cell 21B can be calculated using the ΔSOC1 and SOH1 of the first single cell 21A with the smallest temperature difference from the second single cell 21B among the three first single cell 21A.

[0061] In Figure 8, steps S21 and S22 can be omitted. In this case, if it is determined in step S16 that ΔSOC is greater than or equal to the threshold TH1, and in step S17 that ΔSOC is less than the threshold TH2, the process proceeds to step S23, where, for each second cell 21B, the cell 21 with the smaller temperature difference between it and the second cell 21B (the low-temperature cell 21, cell n, and the high-temperature cell 21, cell n-2, is determined as the first cell 21A that references SOH1. In the following step S18, SOH2 of the second cell 21B is calculated by referencing ΔSOC1 and SOH1 of the first cell 21A determined in step S23, and using the above (Equation 4).

[0062] (Third embodiment) In this embodiment, each individual cell 21 of the battery pack 20 is equipped with a temperature sensor 25 and an impedance sensor 26. In other words, the diagnostic parameters, battery temperature and impedance, are detected for each individual cell 21. In this embodiment, if it is determined that a sensor malfunction has occurred in any of the individual cells 21, the individual cell 21 in which the sensor malfunction occurred is designated as the second individual cell 21B, while the individual cell 21 in which no sensor malfunction was determined to have occurred is designated as the first individual cell 21A, and the SOH2 of the second individual cell 21B is calculated.

[0063] Figure 9 is a flowchart of the SOH calculation process in this embodiment. This process is performed by the BMU30, replacing the process in Figure 4. In Figure 9, the same steps as in Figure 4 are given the same step numbers and detailed explanations are omitted.

[0064] In Figure 9, in steps S11 and S12, the battery temperature and impedance are obtained as parameters used for degradation diagnosis for the first cell 21A, and SOH1 is calculated based on these diagnostic parameters. At this time, all cell 21 are considered as the first cell 21A, and SOH1 is calculated for each cell 21.

[0065] Subsequently, in step S31, it is determined whether or not an abnormality has occurred in the temperature sensor 25 and impedance sensor 26 provided in each cell 21. The abnormality determination can be performed by any method, but for example, it is preferable to determine that a sensor abnormality has occurred when the detected value of the temperature sensor 25 falls outside the specified range, or when the deviation of the detected value in each cell 21 from the average value exceeds a predetermined value. If step S31 is negative, this process ends there. If step S31 is positive, the process proceeds to step S32.

[0066] In step S32, the cell 21 that is determined to have a sensor malfunction is designated as the second cell 21B. In step S33, one of the normal cell 21s that is not determined to have a sensor malfunction is selected as the first cell 21A that references SOH1. Specifically, among the normal cell 21s, the cell 21 with the smallest temperature difference from the cell 21 with a sensor malfunction is selected as the first cell 21A that references SOH1. Alternatively, among the normal cell 21s, a high-temperature cell (e.g., the cell 21 with the highest temperature) or a low-temperature cell (e.g., the cell 21 with the lowest temperature) can also be selected as the first cell 21A that references SOH1.

[0067] Subsequently, in steps S13 to S15, the State of Care (SOC) is calculated for each cell 21 based on its terminal voltage (OCV), and the difference between the SOC at the end of the current vehicle run and the SOC at the end of the previous vehicle run is calculated as ΔSOC. Furthermore, if it is determined in step S16 that ΔSOC is greater than or equal to the threshold TH1, and in step S17 that ΔSOC is less than the threshold TH2, the process proceeds to step S18. In step S18, the ΔSOC1 and SOH1 of the first cell 21A determined in step S33 are referenced, and the SOH2 of the second cell 21B (i.e., the cell 21 with the sensor malfunction) is calculated using (Equation 4) above.

[0068] In the third embodiment described in detail above, it is determined whether or not a sensor abnormality has occurred in the temperature sensor 25 and impedance sensor 26 provided in each cell 21. Cell 21 determined to have a sensor abnormality is designated as the second cell 21B, while cell 21 determined not to have a sensor abnormality is designated as the first cell 21A. The SOH2 of the second cell 21B is then calculated based on the ΔSOC1 and SOH1 of the first cell 21A, which was determined not to have a sensor abnormality. In this case, even after a cell 21 that was initially able to calculate SOH based on sensor detection information becomes unable to calculate SOH due to a sensor abnormality, it is possible to continue calculating SOH.

[0069] In this embodiment, instead of providing a temperature sensor 25 and an impedance sensor 26 to all individual cells 21 of the battery pack 20, it is also possible to provide a temperature sensor 25 and an impedance sensor 26 to at least two or more individual cells 21. In this case as well, the individual cell 21 in which a sensor malfunction is determined to have occurred may be designated as the second individual cell 21B, while the individual cell 21 in which no sensor malfunction is determined to have occurred may be designated as the first individual cell 21A.

[0070] (Other embodiments) The above embodiment may be modified as follows, for example.

[0071] In the SOH calculation process explained in Figure 4, etc., conditions for permitting or prohibiting the calculation of SOH2 of the second cell 21B using the above (Equation 4) may be defined. For example, a prohibition condition may be defined that prohibits the calculation of SOH2 of the second cell 21B based on the voltage-SOC characteristic curve of cell 21 shown in Figure 10.

[0072] In this case, in step S14 of Figure 4, the BMU 30 uses the voltage-SOC characteristic curve to calculate the SOC based on the terminal voltage of the single cell 21, and also calculates ΔSOC (SOC change) that occurs when the battery pack 20 is energized. In addition, in the voltage-SOC characteristic curve shown in Figure 10, the region where the slope of the voltage with respect to SOC is less than or equal to a predetermined value is the flat region Rf, and in step S18, the BMU 30 determines whether or not the terminal voltage of the single cell 21 is in the flat region Rf (voltage determination unit). If it is determined that the terminal voltage is in the flat region Rf, the calculation of SOH2 of the second single cell 21B is not performed. Alternatively, even if the BMU 30 calculates SOH2 for the second single cell 21B, it invalidates the result. In other words, when the terminal voltage of the single cell 21 is in the flat region Rf, the calculation of SOH2 for the second single cell 21B is not performed.

[0073] In the voltage-SOC characteristic curve of cell 21, if the terminal voltage of cell 21 is in the flat region Rf, the change in SOC is small even if the terminal voltage of cell 21 changes, making it difficult to ensure the accuracy of SOC calculation. Therefore, in the voltage-SOC characteristic curve of cell 21, if it is determined that the terminal voltage of cell 21 is in the flat region Rf, the calculation of SOH2 of the second cell 21B is not enabled. This suppresses the inconvenience of a decrease in the calculation accuracy of SOH2 of the second cell 21B due to the low accuracy of SOC calculation of cell 21.

[0074] Furthermore, in the case of single cell 21, since the accuracy of SOC calculation decreases immediately after charging and discharging, it is also possible to configure the system to prohibit (disable) the calculation of SOH2 of the second single cell 21B for a predetermined period immediately after charging and discharging. For example, if the BMU 30 performs an equalization process (cell balancing process) to equalize the terminal voltages of each single cell 21, it may prohibit the calculation of SOH2 of the second single cell 21B until a predetermined time has elapsed thereafter.

[0075] As shown in Figure 11, the battery system 10 may be configured such that multiple voltage sensors 24 are provided to detect the terminal voltage of each cell 21, and the terminal voltage of each cell 21 is detected by one of the voltage sensors 24. In Figure 11, cell 21 (number 2) and cell 21 (number n-1) are the first cell 21A, from which SOH can be calculated using diagnostic parameters. At least two cell 21s must be designated as the first cell 21A. In this case, the first cell 21A and the second cell 21B are combined from cell 21s whose voltage is detected by the same voltage sensor 24, and the SOH2 of the second cell 21B is calculated based on the SOH1 of the first cell 21A.

[0076] For example, in the SOH calculation process shown in Figure 4, the BMU 30 calculates SOH1 for each first cell 21A (step S12). It also calculates SOC based on the voltage detected by the voltage sensor 24, and calculates ΔSOC using the SOC before and after the change due to energization of the battery pack 20 (steps S13 to S15). Furthermore, for each second cell 21B, the BMU 30 combines a first cell 21A whose voltage is detected by the same voltage sensor 24, and uses ΔSOC1 and SOH1 of the first cell 21A to calculate SOH2 for the second cell 21B (step S18).

[0077] In a battery pack 20 where the terminal voltage of each cell 21 is detected by multiple voltage sensors 24, the detection error is equivalent when the voltage is detected by the same voltage sensor 24. In this case, if the first cell 21A and the second cell 21B are combined using cell 21s whose voltage is detected by the same voltage sensor 24, the SOC errors occurring in each of those cell 21A and 21B will be equivalent, and the same error will be added to both the numerator and denominator of the ΔSOC ratio in (Equation 4) above. Therefore, the ΔSOC ratio becomes less susceptible to the voltage detection error. Taking this into consideration, for each second cell 21B, the SOH2 of the second cell 21B is calculated using the ΔSOC1 and SOH1 of the first cell 21A, whose voltage is detected by the same voltage sensor 24. This ensures the accuracy of the SOH calculation and allows for the proper calculation of the SOH of all cell 21s.

[0078] The SOH calculation process shown in Figure 4 may be configured to be performed while the vehicle's power switch is ON (while the vehicle is running). In this case, while the vehicle is running, the voltage and current at multiple points are measured for each cell 21, the OCV is calculated from the intercept when these voltages and currents are plotted on a two-dimensional coordinate system, and the SOC of each cell 21 is calculated based on the OCV.

[0079] The detection unit for detecting diagnostic parameters may consist only of an impedance sensor 26. Alternatively, some of the single cells 21 may be designated as the first single cell 21A, and impedance detection may be performed only on the first single cell 21A.

[0080] The battery system 10 is not limited to being mounted on a vehicle; for example, it may be mounted on other mobile bodies such as aircraft or ships. Furthermore, the battery system 10 is not limited to being mounted on a mobile body; it may be a stationary system.

[0081] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0082] The technical concepts extracted from the above-described embodiments are described below. [Configuration 1] A battery diagnostic device (30) is applied to a battery system (10) comprising a battery pack (20) in which multiple single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the multiple single cells for detecting parameters for degradation diagnosis, and calculates the State of Health (SOH) which indicates the degree of degradation of each single cell, A first calculation unit that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation unit calculates the amount of change in SOC caused by energizing the aforementioned plurality of single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation unit is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, the third calculation unit calculates the value obtained by multiplying the change ratio, which is the ratio of the change in SOC of the first single cell to the change in SOC of the second single cell, by the SOH of the first single cell, and this value is designated as the SOH of the second single cell. A battery diagnostic device equipped with the following features. [Configuration 2] The first calculation unit acquires the parameters detected by the detection unit for the high-temperature cell among the plurality of single cells that become relatively hot when the battery pack is energized, and calculates the SOH of the high-temperature cell based on those parameters. The battery diagnostic device according to configuration 1, wherein the third calculation unit calculates the SOH of the second cell, with the high-temperature battery being the first cell. [Configuration 3] The first calculation unit acquires the parameters detected by the detection unit for the low-temperature cell among the plurality of single cells that are relatively low temperature when the battery pack is energized, and calculates the SOH of the low-temperature cell based on those parameters. The battery diagnostic device according to configuration 1, wherein the third calculation unit calculates the SOH of the second cell, with the low-temperature battery being the first cell. [Structure 4] The first calculation unit selects at least two of the plurality of single cells as the first single cell, acquires the parameters detected by the detection unit, and calculates the SOH based on those parameters. The battery diagnostic device according to configuration 1, wherein the third calculation unit calculates the SOH of the second single cell for each second single cell, using the SOC change amount and SOH of the first single cell, which has a small temperature difference with the second single cell among at least two of the first single cells when the battery pack is energized. [Composition 5] The first calculation unit selects two or more single cells from the plurality of single cells, including a low-temperature cell that is relatively low in temperature when the battery pack is energized, as the first single cell, acquires the parameters detected by the detection unit, and calculates the SOH based on those parameters. The system includes a temperature determination unit that determines whether the overall temperature of the battery pack, which is the battery pack temperature, is higher or lower than a predetermined temperature. The third calculation unit is, If it is determined that the temperature of the battery pack is lower than the predetermined temperature, the low-temperature battery is considered the first single cell, and the SOH of the second single cell is calculated. The battery diagnostic device according to configuration 1, which, when it is determined that the temperature of the battery pack is higher than the predetermined temperature, calculates the SOH of the second single cell for each of the two or more first single cells, using the change in SOC and the SOH of the first single cell that has a small temperature difference with the second single cell under energized conditions of the battery pack. [Composition 6] In the aforementioned battery system, a plurality of voltage sensors (24) are provided to detect the terminal voltage of each of the individual cells. The first calculation unit selects at least two of the plurality of single cells as the first single cell, acquires the parameters detected by the detection unit, and calculates the SOH based on those parameters. The second calculation unit calculates the SOC based on the voltage detected by the voltage sensor, and calculates the amount of change in the SOC based on the SOC before and after the change due to the energization of the battery pack. The battery diagnostic device according to Configuration 1, wherein the third calculation unit combines at least two of the first cells, each of which voltage detection is performed by the same voltage sensor, for each second cell, and calculates the SOH of the second cell using the SOC change amount and SOH of the first cell. [Composition 7] In the battery system, the detection unit is provided in at least two of the plurality of single cells. The single cell, which is provided with the detection unit, is further equipped with an abnormality determination unit that determines whether or not an abnormality has occurred in the detection unit. The battery diagnostic device according to any one of configurations 1 to 6, wherein the third calculation unit determines that an abnormality has occurred in the detection unit by the abnormality determination unit to be the second cell, and determines that the cell provided with the detection unit and that no abnormality has occurred in the detection unit to be the first cell, and calculates the SOH of the second cell. [Structure 8] The voltage-SOC characteristic curve, which shows the relationship between the voltage of the single cell and the SOC, includes a voltage determination unit that determines whether the voltage of the single cell falls within a flat region where the slope of the voltage relative to the SOC is less than or equal to a predetermined value. The second calculation unit calculates the SOC based on the voltage of the single cell using the voltage-SOC characteristic curve, and calculates the amount of change in SOC based on the SOC before and after the change due to the energization of the battery pack. The battery diagnostic device according to any one of configurations 1 to 7, wherein the third calculation unit determines that the voltage of the single cell is in the flat region, and in this case, the calculation of the SOH of the second single cell is not enabled. [Composition 9] A change amount determination unit that determines whether the amount of change in SOC calculated by the second calculation unit is greater than a predetermined value, If the change amount determination unit determines that the change amount of SOC is greater than a predetermined value, a fourth calculation unit calculates the SOH based on the change amount of SOC and the integrated value of the current that flowed through the single cell during the period in which the change amount of SOC was calculated, instead of the calculation of the SOH by the third calculation unit. A battery diagnostic device comprising any one of configurations 1 to 8. [Explanation of Symbols]

[0083] 10...Battery system, 20...Battery pack, 21...Single cell, 25...Temperature sensor, 26...Impedance sensor, 30...BMU.

Claims

1. A battery diagnostic device (30) is applied to a battery system (10) comprising a battery pack (20) in which a plurality of single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the plurality of single cells for detecting parameters for deterioration diagnosis, and calculates the State of Health (SOH) which indicates the degree of deterioration of each single cell, A first calculation unit that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation unit calculates the amount of change in SOC caused by energizing the aforementioned plurality of single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation unit is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, the third calculation unit calculates the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, as the SOH of the second single cell. Equipped with, The first calculation unit acquires the parameters detected by the detection unit for the low-temperature cell among the plurality of single cells that are relatively low temperature when the battery pack is energized, and calculates the SOH of the low-temperature cell based on those parameters. The third calculation unit is a battery diagnostic device that calculates the SOH of the second cell, with the low-temperature battery being the first cell.

2. A battery diagnostic device (30) is applied to a battery system (10) comprising a battery pack (20) in which a plurality of single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the plurality of single cells for detecting parameters for deterioration diagnosis, and calculates the State of Health (SOH) which indicates the degree of deterioration of each single cell, A first calculation unit that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation unit calculates the amount of change in SOC caused by energizing the aforementioned plurality of single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation unit is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, the third calculation unit calculates the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, as the SOH of the second single cell. Equipped with, The first calculation unit selects at least two of the plurality of single cells as the first single cell, acquires the parameters detected by the detection unit, and calculates the SOH based on those parameters. The third calculation unit calculates the SOH of the second single cell for each second single cell, using the SOC change amount and SOH of at least two of the first single cells, which have a small temperature difference with the second single cell under energized conditions of the battery pack.

3. A battery diagnostic device (30) is applied to a battery system (10) comprising a battery pack (20) in which a plurality of single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the plurality of single cells for detecting parameters for deterioration diagnosis, and calculates the State of Health (SOH) which indicates the degree of deterioration of each single cell, A first calculation unit that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation unit calculates the amount of change in SOC caused by energizing the aforementioned plurality of single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation unit is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, the third calculation unit calculates the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, as the SOH of the second single cell. Equipped with, The first calculation unit selects two or more single cells from the plurality of single cells, including a low-temperature cell that is relatively low in temperature when the battery pack is energized, as the first single cell, acquires the parameters detected by the detection unit, and calculates the SOH based on those parameters. The system further includes a temperature determination unit that determines whether the overall temperature of the battery pack, which is the battery pack temperature, is higher or lower than a predetermined temperature. The third calculation unit is, If it is determined that the temperature of the battery pack is lower than the predetermined temperature, the low-temperature battery is treated as the first single cell, and the SOH of the second single cell is calculated. A battery diagnostic device that, when it is determined that the temperature of the battery pack is higher than the predetermined temperature, calculates the SOH of the second single cell for each of the two or more first single cells, using the SOC change amount and SOH of the first single cell that has a small temperature difference with the second single cell under energized conditions of the battery pack.

4. A battery diagnostic device (30) is applied to a battery system (10) comprising a battery pack (20) in which a plurality of single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the plurality of single cells for detecting parameters for deterioration diagnosis, and calculates the State of Health (SOH) which indicates the degree of deterioration of each single cell, The battery system is provided with a plurality of voltage sensors (24) for detecting the terminal voltage of each of the individual cells. A first calculation unit that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation unit calculates the amount of change in SOC caused by energizing the aforementioned plurality of single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation unit is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, the third calculation unit calculates the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, as the SOH of the second single cell. Equipped with, The first calculation unit selects at least two of the plurality of single cells as the first single cell, acquires the parameters detected by the detection unit, and calculates the SOH based on those parameters. The second calculation unit calculates the SOC based on the voltage detected by the voltage sensor, and calculates the amount of change in the SOC based on the SOC before and after the change due to the energization of the battery pack. The third calculation unit is a battery diagnostic device that, for each second single cell, combines at least two of the first single cells, the first single cells whose voltage is detected by the same voltage sensor, and uses the SOC change amount and SOH of the first single cell to calculate the SOH of the second single cell.

5. In the battery system, the detection unit is provided in at least two of the plurality of single cells. The single cell, which is provided with the detection unit, is further equipped with an abnormality determination unit that determines whether or not an abnormality has occurred in the detection unit. The battery diagnostic device according to any one of claims 1 to 4, wherein the third calculation unit determines that an abnormality has occurred in the detection unit by the abnormality determination unit to be the second single cell, and determines that the single cell provided with the detection unit and that no abnormality has occurred in the detection unit to be the first single cell, and calculates the SOH of the second single cell.

6. The voltage-SOC characteristic curve, which shows the relationship between the voltage of the single cell and the SOC, includes a voltage determination unit that determines whether the voltage of the single cell falls within a flat region where the slope of the voltage relative to the SOC is less than or equal to a predetermined value. The second calculation unit calculates the SOC based on the voltage of the single cell using the voltage-SOC characteristic line, and calculates the amount of SOC change based on the SOC before and after the change due to the energization of the battery pack. The battery diagnostic device according to any one of claims 1 to 4, wherein the third calculation unit determines that the voltage of the single cell is in the flat region, and in this case, the calculation of the SOH of the second single cell is not made valid.

7. A change amount determination unit that determines whether the amount of change in SOC calculated by the second calculation unit is greater than a predetermined value, If the change amount determination unit determines that the change amount of SOC is greater than a predetermined value, a fourth calculation unit calculates the SOH based on the change amount of SOC and the integrated value of the current that flowed through the single cell during the period in which the change amount of SOC was calculated, instead of the calculation of the SOH by the third calculation unit. A battery diagnostic device according to any one of claims 1 to 4, comprising:

8. A battery diagnostic device (30) is applied to a battery system (10) comprising a battery pack (20) in which a plurality of single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the plurality of single cells for detecting parameters for deterioration diagnosis, and calculates the State of Health (SOH) which indicates the degree of deterioration of each single cell, The battery system is provided with the detection unit in at least two of the plurality of single cells. A first calculation unit that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation unit calculates the amount of change in SOC caused by energizing the aforementioned plurality of single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation unit is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, the third calculation unit calculates the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, as the SOH of the second single cell. An abnormality determination unit that determines whether or not an abnormality has occurred in the detection unit in the single cell provided with the detection unit, Equipped with, The third calculation unit calculates the State of Health (SOH) of the second cell, with the cell determined by the abnormality determination unit to have an abnormality in the detection unit being designated as the second cell, and the cell provided with the detection unit and determined not to have an abnormality in the detection unit being designated as the first cell.

9. A battery diagnostic device (30) is applied to a battery system (10) comprising a battery pack (20) in which a plurality of single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the plurality of single cells for detecting parameters for deterioration diagnosis, and calculates the State of Health (SOH) which indicates the degree of deterioration of each single cell, A first calculation unit that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation unit calculates the amount of change in SOC caused by energizing the aforementioned plurality of single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation unit is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, the third calculation unit calculates the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, as the SOH of the second single cell. A voltage determination unit determines whether the voltage of the single cell falls within a flat region where the slope of the voltage relative to the SOC is less than or equal to a predetermined value, in the voltage-SOC characteristic curve showing the relationship between the voltage of the single cell and the SOC. Equipped with, The second calculation unit calculates the SOC based on the voltage of the single cell using the voltage-SOC characteristic line, and calculates the amount of SOC change based on the SOC before and after the change due to the energization of the battery pack. The battery diagnostic device wherein the third calculation unit determines that the voltage of the single cell is in the flat region, and in such a case, it does not enable the calculation of the SOH of the second single cell.

10. A battery diagnostic device (30) is applied to a battery system (10) comprising a battery pack (20) in which a plurality of single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the plurality of single cells for detecting parameters for deterioration diagnosis, and calculates the State of Health (SOH) which indicates the degree of deterioration of each single cell, A first calculation unit that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation unit calculates the amount of change in SOC caused by energizing the aforementioned plurality of single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation unit is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, the third calculation unit calculates the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, as the SOH of the second single cell. A change amount determination unit that determines whether the amount of change in SOC calculated by the second calculation unit is greater than a predetermined value, If the change amount determination unit determines that the change amount of SOC is greater than a predetermined value, a fourth calculation unit calculates the SOH based on the change amount of SOC and the integrated value of the current that flowed through the single cell during the period in which the change amount of SOC was calculated, instead of the calculation of the SOH by the third calculation unit. A battery diagnostic device equipped with the following features.

11. A program is applied to a battery system (10) comprising a battery pack (20) in which multiple single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the multiple single cells for detecting parameters for degradation diagnosis, and is executed by a control device (30) to calculate the State of Health (SOH) which indicates the degree of degradation of each single cell, A first calculation process that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation process for calculating the amount of change in SOC caused by energizing the aforementioned multiple single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation process is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, a third calculation process is performed to calculate the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, and this value is designated as the SOH of the second single cell. Equipped with, In the first calculation process, for the low-temperature cell among the plurality of single cells that is relatively low in temperature when the battery pack is energized, the parameters detected by the detection unit are obtained, and the SOH of the low-temperature cell is calculated based on those parameters. The third calculation process is a program that calculates the SOH of the second cell, with the low-temperature battery being the first cell.

12. A program is applied to a battery system (10) comprising a battery pack (20) in which multiple single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the multiple single cells for detecting parameters for degradation diagnosis, and is executed by a control device (30) to calculate the State of Health (SOH) which indicates the degree of degradation of each single cell, A first calculation process that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation process for calculating the amount of change in SOC caused by energizing the aforementioned multiple single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation process is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, a third calculation process is performed to calculate the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, and this value is designated as the SOH of the second single cell. Equipped with, In the first calculation process, at least two of the plurality of single cells are designated as the first single cell, the parameters detected by the detection unit are obtained, and the SOH is calculated based on those parameters. The third calculation process is a program that, for each second cell, uses the change in SOC and the SOH of at least two of the first cells, the first cell with the smallest temperature difference from the second cell under energized conditions of the battery pack, to calculate the SOH of the second cell.

13. A program is applied to a battery system (10) comprising a battery pack (20) in which multiple single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the multiple single cells for detecting parameters for degradation diagnosis, and is executed by a control device (30) to calculate the State of Health (SOH) which indicates the degree of degradation of each single cell, A first calculation process that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation process for calculating the amount of change in SOC caused by energizing the aforementioned multiple single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation process is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, a third calculation process is performed to calculate the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, and this value is designated as the SOH of the second single cell. Equipped with, The first calculation process involves selecting two or more single cells from the plurality of single cells, including a low-temperature cell that is relatively low in temperature when the battery pack is energized, as the first single cell, obtaining the parameters detected by the detection unit, and calculating the SOH based on those parameters. The system further includes a temperature determination process that determines whether the overall temperature of the battery pack, which is the battery pack temperature, is higher or lower than a predetermined temperature. In the third calculation process described above, If it is determined that the temperature of the battery pack is lower than the predetermined temperature, the low-temperature battery is treated as the first single cell, and the SOH of the second single cell is calculated. A program that, when it is determined that the temperature of the battery pack is higher than the predetermined temperature, calculates the SOH of the second single cell for each of the two or more first single cells, using the SOC change and SOH of the first single cell that has a small temperature difference with the second single cell under energized conditions of the battery pack.

14. A program is applied to a battery system (10) comprising a battery pack (20) in which multiple single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the multiple single cells for detecting parameters for degradation diagnosis, and is executed by a control device (30) to calculate the State of Health (SOH) which indicates the degree of degradation of each single cell, The battery system is provided with a plurality of voltage sensors (24) for detecting the terminal voltage of each of the individual cells. A first calculation process that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation process for calculating the amount of change in SOC caused by energizing the aforementioned multiple single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation process is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, a third calculation process is performed to calculate the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, and this value is designated as the SOH of the second single cell. Equipped with, In the first calculation process, at least two of the plurality of single cells are designated as the first single cell, the parameters detected by the detection unit are obtained, and the SOH is calculated based on those parameters. In the second calculation process, the SOC is calculated based on the voltage detected by the voltage sensor, and the amount of change in the SOC is calculated based on the SOC before and after the change due to the energization of the battery pack. The third calculation process is a program that, for each second cell, combines at least two of the first cells whose voltage is detected by the same voltage sensor, and uses the SOC change amount and SOH of the first cell to calculate the SOH of the second cell.

15. A program is applied to a battery system (10) comprising a battery pack (20) in which multiple single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the multiple single cells for detecting parameters for degradation diagnosis, and is executed by a control device (30) to calculate the State of Health (SOH) which indicates the degree of degradation of each single cell, The battery system is provided with the detection unit in at least two of the plurality of single cells. A first calculation process that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation process for calculating the amount of change in SOC caused by energizing the aforementioned multiple single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation process is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, a third calculation process is performed to calculate the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, and this value is designated as the SOH of the second single cell. An abnormality determination process for determining whether or not an abnormality has occurred in the detection unit in the single cell provided with the detection unit, Equipped with, In the third calculation process, the program calculates the SOH of the second cell, with the cell determined to have an abnormality in the detection unit by the abnormality determination process being designated as the second cell, and the cell provided with the detection unit and determined not to have an abnormality in the detection unit being designated as the first cell.

16. A program is applied to a battery system (10) comprising a battery pack (20) in which multiple single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the multiple single cells for detecting parameters for degradation diagnosis, and is executed by a control device (30) to calculate the State of Health (SOH) which indicates the degree of degradation of each single cell, A first calculation process that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation process for calculating the amount of change in SOC caused by energizing the aforementioned multiple single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation process is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, a third calculation process is performed to calculate the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, and this value is designated as the SOH of the second single cell. A voltage determination process is performed to determine whether the voltage of the single cell falls within a flat region where the slope of the voltage relative to the SOC is less than or equal to a predetermined value, in the voltage-SOC characteristic curve showing the relationship between the voltage of the single cell and the SOC. Equipped with, In the second calculation process, the SOC is calculated based on the voltage of the single cell using the voltage-SOC characteristic curve, and the amount of change in the SOC is calculated using the SOC before and after the change due to the energization of the battery pack. In the third calculation process, if it is determined that the voltage of the single cell is within the flat region, the program does not enable the calculation of the SOH of the second single cell.

17. A program is applied to a battery system (10) comprising a battery pack (20) in which multiple single cells (21) are connected in series, and a detection unit (25, 26) provided on at least one of the multiple single cells for detecting parameters for degradation diagnosis, and is executed by a control device (30) to calculate the State of Health (SOH) which indicates the degree of degradation of each single cell, A first calculation process that acquires the parameters detected by the detection unit for at least one of the plurality of single cells and calculates the SOH based on those parameters, A second calculation process for calculating the amount of change in SOC caused by energizing the aforementioned multiple single cells, When, among the plurality of single cells, the single cell for which the SOH has been calculated by the first calculation process is designated as the first single cell, and the single cell for which the SOH has not been calculated is designated as the second single cell, a third calculation process is performed to calculate the value obtained by multiplying the change ratio, which is the ratio of the change amount of the SOC of the first single cell to the change amount of the SOC of the second single cell, by the SOH of the first single cell, and this value is designated as the SOH of the second single cell. A change amount determination process that determines whether the amount of change in SOC calculated by the second calculation process is greater than a predetermined value, If the change amount determination process determines that the change amount of SOC is greater than a predetermined value, a fourth calculation process is performed to calculate the SOH based on the change amount of SOC and the integrated value of the current that flowed through the single cell during the period in which the change amount of SOC was calculated, instead of calculating the SOH by the third calculation process. A program that includes the following features.

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