JP7402132B2 - diagnostic system - Google Patents

Description

The present invention relates to a diagnostic system for secondary batteries.

As a method for diagnosing the deterioration state of a secondary battery that functions as a vehicle drive battery, the differential characteristics of the charge/discharge curve of the secondary battery are determined, and the deterioration state of the secondary battery is determined from the information of the peak location in the differential characteristic. A method of determining the SOH (State of Health) is known (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2017-227539

Here, in order to estimate the deterioration state of the drive battery (secondary battery) with high precision, it is necessary to obtain the peak shape in the differential characteristics of the charge/discharge curve with high precision. The timing for acquiring the differential curve may be when the vehicle is running or when the vehicle is not running. From the viewpoint of shortening the dead time of the vehicle due to charge/discharge control, it is preferable to obtain the differential curve while the vehicle is running. However, in order to obtain the peak shape with high precision, it is necessary to perform charging and discharging control in a low and constant current state. , it is difficult to perform charge/discharge control under low and constant current conditions. For this reason, conventionally, it has been difficult to diagnose the deterioration state of the drive battery while the vehicle is running.

The present invention has been made in view of the above circumstances, and an object of the present invention is to appropriately diagnose the deterioration state of a secondary battery while driving.

A diagnostic system according to one aspect of the present invention includes an acquisition unit that acquires an SOC value for a plurality of secondary batteries that function as a drive battery and an auxiliary battery for a vehicle and that are configured to be separable from each other; Based on the SOC value acquired by the unit, it is determined whether the plurality of secondary batteries are in a state where the peak shape of the differential curve of the charge/discharge curve can be acquired by charge/discharge control, and the peak shape can be acquired. a battery control unit that performs disconnection control of the plurality of secondary batteries so that some of the secondary batteries included in the plurality of secondary batteries function only as auxiliary batteries when the For some secondary batteries that now function only as batteries for auxiliary equipment, the peak shape of the differential curve of the charge/discharge curve is obtained through charge/discharge control, and based on the peak shape, the deterioration of multiple secondary batteries can be determined. An estimator that estimates a state.

According to the diagnostic system according to one aspect of the present invention, it is determined that a plurality of secondary batteries functioning as a drive battery and an auxiliary battery of a vehicle are in a state where the peak shape of a differential curve can be obtained. In this case, separation control of the plurality of secondary batteries is performed so that some of the secondary batteries included in the plurality of secondary batteries function only as auxiliary equipment batteries. Then, in this diagnostic system, the peak shape of the differential curve is obtained for some secondary batteries that have been separated and now function only as auxiliary batteries, and the deterioration state of multiple secondary batteries is estimated. . In order to obtain the peak shape with high accuracy, it is necessary to perform charging and discharging control in a low and constant current state. It is difficult to control charging and discharging in a current and constant current state. In this regard, in the diagnostic system according to one aspect of the present invention, when a part of the secondary battery, which normally serves as a drive battery and an auxiliary battery, is in a state where the peak shape of the differential curve can be obtained. In addition, it functions only as a battery for auxiliary equipment. Unlike the driving battery, the auxiliary equipment battery tends to maintain a low current and constant current state even when the auxiliary equipment performs normal operation. By acquiring the peak shapes of some of the secondary batteries in a constant current state, the peak shapes of the differential curves of the some of the secondary batteries can be acquired with high accuracy. Some of the secondary batteries are included in multiple secondary batteries before being separated, and function as drive batteries and auxiliary batteries together with other secondary batteries included in the multiple secondary batteries. Therefore, it is considered that the deterioration state is the same as that of other secondary batteries included in the plurality of secondary batteries. Therefore, by estimating the deterioration states of a plurality of secondary batteries based on the peak shapes of some of the secondary batteries, the deterioration states of the plurality of secondary batteries can be estimated with high accuracy. As described above, according to the diagnostic system according to one aspect of the present invention, the deterioration state of the secondary battery can be appropriately diagnosed during driving.

The battery control unit controls the peak shape of the differential curve of the charging/discharging curve of some of the secondary batteries by charge/discharging control when some of the secondary batteries are disconnected and function only as auxiliary batteries. If this is not possible, some of the secondary batteries may be integrated with other secondary batteries included in the multiple secondary batteries, and the multiple secondary batteries may function as drive batteries and auxiliary batteries. It's okay. According to such a configuration, when some of the secondary batteries that have been separated for deterioration state estimation are not in a state where the peak shape can be obtained (not in such an SOC state), the It is possible to appropriately integrate one secondary battery with another secondary battery, and it is possible to prevent a plurality of secondary batteries from being senselessly separated.

According to one aspect of the present invention, it is possible to appropriately diagnose the deterioration state of a secondary battery while driving.

FIG. 2 is a functional block diagram of a secondary battery diagnostic system. FIG. 3 is a diagram schematically showing table data. It is a figure showing an example of a charge-discharge curve of a secondary battery. It is a figure showing an example of the differential characteristic of the charge-discharge curve of a secondary battery. FIG. 2 is a circuit diagram illustrating integration and separation of secondary batteries. FIG. 2 is a circuit diagram illustrating integration and separation of secondary batteries. FIG. 2 is a circuit diagram illustrating integration and separation of secondary batteries. FIG. 2 is a circuit diagram illustrating integration and separation of secondary batteries. FIG. 2 is a circuit diagram illustrating integration and separation of secondary batteries. FIG. 2 is a circuit diagram illustrating integration and separation of secondary batteries. FIG. 2 is a circuit diagram illustrating integration and separation of secondary batteries. It is a flowchart which shows the diagnostic process (diagnosis method) of a secondary battery.

Hereinafter, various embodiments will be described in detail with reference to the drawings. In each drawing, the same or equivalent parts are given the same reference numerals, and redundant explanations of the same or equivalent parts will be omitted.

FIG. 1 is a functional block diagram of a secondary battery diagnostic system 10. The secondary battery in this embodiment is, for example, a vehicle-mounted lithium ion battery, but may be any other secondary battery. The secondary battery in this embodiment functions, for example, as a vehicle drive battery and an auxiliary battery (details will be described later). In this embodiment, the description will be made assuming that the secondary battery is a lithium ion battery that functions as a vehicle drive battery and an auxiliary battery. More specifically, the secondary battery is, for example, a lithium ion battery using a graphite negative electrode.

First, an overview of the secondary battery diagnostic system 10 according to the present embodiment will be described with reference to FIGS. 2 to 4. The diagnostic system 10 has, for example, a BMS (Battery Management System) function that estimates and monitors the state of a secondary battery that functions as a drive battery and an auxiliary battery. The diagnostic system 10 is a system that non-destructively estimates the internal state of a secondary battery, and specifically estimates the value of SOC (State of Charge) representing the remaining capacity of the secondary battery. The diagnostic system 10 estimates the SOC value using a well-known technique based on the current, voltage, and surface temperature of the secondary battery. Here, in order to estimate the SOC value with high accuracy, it is preferable that the state of deterioration (SOH) of the secondary battery be taken into account (that is, the SOC value is corrected based on the SOH value). The diagnostic system 10 estimates the SOC value with high accuracy by estimating the SOH value and correcting the SOC value using the SOH value.

The diagnostic system 10 determines the charge/discharge curve of the secondary battery (see FIG. 3) based on the current and voltage of the secondary battery measured during charging/discharging, and further calculates the differential characteristics of the charge/discharge curve (differential curve , see FIG. 4), and the state of deterioration (SOH) of the secondary battery is estimated based on the differential curve.

FIG. 3 is a diagram showing an example of a charge/discharge curve of a secondary battery. As shown in Figure 3, the charge-discharge curve is derived based on the current and voltage of the secondary battery during charging and discharging, with the horizontal axis representing capacity (mAh) and the vertical axis representing voltage (V). . FIG. 4 is a diagram showing an example of differential characteristics (differential curve) of a charge/discharge curve of a secondary battery. As shown in Figure 4, the differential curve is derived based on the charge/discharge curve, with the horizontal axis representing capacity (SOC (%)) and the vertical axis representing dV/dQ (V is voltage, Q is capacity). .

As shown in FIG. 4, in the differential curve, a peak (a locally convex portion of the curve) occurs in both charging and discharging. That is, in the example of FIG. 4, two peaks P1 and P2 occur in the charging curve, and two peaks P3 and P4 occur in the discharging curve. Information on such peaks (the shape and position of the peaks) is important information in estimating the deterioration state of the secondary battery.

Specifically, the diagnostic system 10 uses on-board data (see FIG. 2) that records differential curves of charge/discharge curves for each combination of secondary battery temperature (internal temperature), deterioration state, and C rate. is stored in advance, and the deterioration state of the secondary battery is derived by comparing the derived differential curve with the differential curve of bench data (by comparing the shapes and positions of their peaks). That is, the diagnostic system 10 identifies, from among the on-board data, data that matches the information on the temperature and C rate of the secondary battery, which are charge/discharge conditions related to charge/discharge control, and has similar peak information in the differential curve. However, the deterioration state of the data is regarded as the deterioration state of the secondary battery to be diagnosed. Note that the C rate is the magnitude of current when charging and discharging a battery, and is derived based on the current. The C rate indicates the speed of charging and discharging.

Here, when obtaining a differential curve of a charging/discharging curve in order to estimate the above-mentioned deterioration state, charging/discharging of the secondary battery is normally performed when the vehicle is stopped. In order to derive the state of deterioration (SOH) with high precision, it is necessary to obtain the peak of the differential curve in an appropriate shape. In this regard, when charging and discharging are performed at a relatively high C rate (i.e., high current), the chemical structure change (internal structure change) of the secondary battery progresses rapidly, and the data sampling sensitivity of the charge and discharge curve is insufficient. Therefore, it may not be possible to obtain a peak with an appropriate shape. Therefore, from the viewpoint of appropriately obtaining the shape and position of the peak, charging and discharging are performed at a relatively low C rate (ie, low current). This causes a problem in that the time required for charging and discharging becomes longer, and the time during which the secondary battery does not function as a vehicle drive battery and an auxiliary battery (dead time) becomes longer.

From the viewpoint of reducing dead time, it is preferable to perform charging/discharging control to obtain a differential curve of a charging/discharging curve while the vehicle is running. However, in order to obtain the peak shape of the differential curve with high precision, it is necessary to perform charging and discharging control in a low and constant current state. Inside the battery, it is difficult to control charging and discharging in a low and constant current state. For these reasons, it has conventionally been difficult to diagnose the deterioration state of the secondary battery that functions as a driving battery while the vehicle is running.

The diagnostic system 10 realizes an appropriate diagnosis of the deterioration state of a secondary battery (driving battery) during driving, which has been difficult in the past. As mentioned above, regarding the secondary battery that functions as a drive battery, the electric power changes drastically during driving, so conventionally it has been difficult to control charging and discharging while driving. In this regard, the inventors of the present invention have found that when functioning as an auxiliary battery, even during operation, charging and discharging of the secondary battery is controlled at a low current (low C rate) and constant current state. I focused on what I could do. The present inventors have developed a state in which some of the plurality of secondary batteries, which normally function as driving batteries, are separated from other secondary batteries and functioned only as auxiliary batteries. We have found that by performing charge/discharge control and obtaining the peak shape, it is possible to appropriately estimate the deterioration state of the secondary battery that functions as the drive battery.

That is, the diagnostic system 10 includes a plurality of secondary batteries that are configured to be separable from each other and function as a vehicle drive battery and an auxiliary battery. Then, the diagnostic system 10 acquires SOC values for the plurality of secondary batteries, and determines whether the plurality of secondary batteries are in a state where the peak shape of the differential curve can be obtained by charge/discharge control (for example, if there are two peaks) Among them, if the SOC value is small enough to obtain the peak shape on the low SOC side, and if the peak shape can be obtained, some of the secondary batteries included in the plurality of secondary batteries For some of the secondary batteries that now function only as auxiliary batteries, the differential curve is The peak shape is acquired, and the deterioration state of the plurality of secondary batteries is estimated based on the peak shape.

Below, with reference to FIG. 1, the details of the functions of the secondary battery diagnostic system 10 will be described. As shown in FIG. 1, the diagnostic system 10 includes a storage section 11, an acquisition section 12, a battery control section 13, and an SOH estimation section 14 (estimation section).

The storage unit 11 is a database that stores bench data (see FIG. 2) in which differential curves of charging and discharging curves of the secondary battery are recorded for each combination of temperature, deterioration state, and C rate of the secondary battery. Such bench data is prepared in advance for each type of battery, for example.

The acquisition unit 12 acquires the values of current and voltage detected during charging or discharging. The acquisition unit 12 acquires the current value flowing through each secondary battery 22 from the current sensor 21 of the battery module 2 configured from a plurality of secondary batteries 22. The acquisition unit 12 also acquires the voltage value applied to each secondary battery 22 from a voltage sensor that measures the voltage between the terminals of the plurality of secondary batteries 22 that constitute the battery module 2 . In a normal state, the plurality of secondary batteries 22 are integrated and function as a single driving battery and an auxiliary battery. The plurality of secondary batteries 22 are configured to be able to be separated from each other. That is, the plurality of secondary batteries 22 are configured such that only a portion thereof can be separated (details will be described later). The acquisition unit 12 estimates SOC values for the plurality of secondary batteries 22 according to the acquired current and voltage values. The acquisition unit 12 estimates the SOC value based on the current, voltage, surface temperature of the secondary battery 22, etc. using a conventionally known technique. As described above, the acquisition unit 12 acquires the SOC values of the plurality of secondary batteries 22.

The acquisition unit 12 also acquires information on temperature, deterioration state, and C rate as charging and discharging conditions related to charging and discharging control of the secondary battery 22. The temperature is the internal temperature of the secondary battery 22, and is derived according to, for example, the surface temperature of the secondary battery 22 and the current detected by the current sensor 21 of the battery module 2. The deterioration state is, for example, the deterioration state of the secondary battery 22 estimated from the driving history of the vehicle. The C rate may be a predetermined value or may be derived according to the current detected by the current sensor 21.

First, the battery control unit 13 determines, based on the SOC value acquired by the acquisition unit 12, whether the plurality of secondary batteries 22 are in a state where the peak shape of the differential curve of the charge/discharge curve can be acquired by charge/discharge control. Determine whether For example, when it is desired to obtain the shape of peak P3 in the discharge curve of the differential curve (the shape of peak P3 on the low SOC side) as shown in FIG. From the above data, a differential curve (discharge curve) matching the charge/discharge condition acquired by the acquisition unit 12 is specified, and the SOC value corresponding to the peak P3 in the discharge curve is specified. Then, the battery control unit 13 determines that the SOC value acquired by the acquisition unit 12 is approaching the SOC value specified according to the charging/discharging conditions (by performing discharge control for a predetermined period of time, the SOC value is (This is a state where the SOC value corresponds to peak P3.) It is determined whether the state is such that the shape of peak P3 can be obtained. An example in which the diagnostic system 10 performs discharge control will be described below.

If the battery control unit 13 determines that the plurality of secondary batteries 22 are in a state where the peak shape of the differential curve can be acquired, some of the secondary batteries 22 included in the plurality of secondary batteries 22 are connected to the auxiliary equipment. The plurality of secondary batteries 22 are controlled to be separated so that they function only as batteries for use. That is, the battery control unit 13 has determined that the state is such that peak shapes can be obtained for the plurality of secondary batteries 22, which are all integrated and function as a vehicle drive battery and an auxiliary battery in a normal state. In this case, a part of the secondary battery 22 is separated and the separated secondary battery 22 is made to function only as an auxiliary battery. In addition, when some of the secondary batteries 22 are disconnected and function as auxiliary batteries and some of the secondary batteries 22 are not in a state where the peak shape of the differential curve can be obtained, the battery control unit 13 In this case, some of the secondary batteries 22 may be integrated with other secondary batteries 22, and the plurality of secondary batteries 22 may function as a driving battery and an auxiliary battery.

Integration and separation of the secondary battery 22 will be explained with reference to FIGS. 5 to 11. 5 to 11 are circuit diagrams illustrating the integration and separation of the secondary batteries 22. In FIGS. 5 to 11, the plurality of secondary batteries 22 are referred to as a main battery 53 or an auxiliary battery 54 for convenience. When the main battery 53 and the auxiliary battery 54 are integrated, they are not distinguished and both function as a drive battery and an auxiliary battery. On the other hand, when the main battery 53 and the auxiliary battery 54 are separated, the main battery 53 functions only as a driving battery, and the auxiliary battery 54 functions only as an auxiliary battery. For convenience of explanation, only one main battery 53 and one auxiliary battery 54 are shown in FIGS. 5 to 11. 5 to 11, a circuit (parallel circuit) including a motor 51, an inverter 52, a main battery 53, an auxiliary battery 54, an auxiliary machine 55, and relays 91, 91, 92, 92, 93, and 93 is shown. ing. Further, FIGS. 5 to 11 show the external charger 100 when charging the vehicle when the vehicle is not running.

First, when battery integration is used (when all the secondary batteries 22 function as drive batteries and auxiliary equipment batteries), the battery control unit 13 controls the main engine battery 53 and the auxiliary equipment battery 54 to be integrated. The relays 91 and 91 between the main battery 53 and the auxiliary battery 54 are turned on so that the battery 53 and the auxiliary battery 54 together supply power to the motor 51 and the auxiliary battery 55 as one battery (Fig. 5 reference).

Further, when the batteries are used separately (when the main engine battery 53 functions only as a driving battery and the auxiliary equipment battery 54 functions only as an auxiliary equipment battery), the battery control unit 13 controls the main engine battery 53 and the auxiliary equipment battery. 54 is separated, and the relays 91 and 91 between the main engine battery 53 and the auxiliary equipment battery 54 are turned off so that the main equipment battery 53 supplies power to the motor 51 and the auxiliary equipment battery 54 supplies power to the auxiliary equipment 55. (see Figure 6). In the state shown in FIG. 6, power from the main battery 53 is supplied only to the motor 51 side, and power from the auxiliary battery 54 is supplied only to the auxiliary machine 55 side. As will be described later, in this state, the peak shape of the discharge curve of the auxiliary battery 54 is obtained through discharge control. Note that the auxiliary battery 54 is not charged by regeneration during driving. Therefore, when the SOC of the auxiliary battery 54 becomes 0%, power is supplied to the auxiliary battery 55 from the separated main battery 53 side.

Further, when charging is performed from the external charger 100 during battery integration, the battery control unit 13 further charges the external charger 100 from the battery integration state (the state in which the relays 91 and 91 are turned on). The relays 93, 93 connecting to the machine battery 54 are turned on (see FIG. 7). Note that the battery control unit 13 may turn ON the relays 92 and 92 that connect the external charger 100 and the main battery 53 instead of the relays 93 and 93.

Furthermore, when charging is performed from the external charger 100 when the batteries are separated, the battery with the lower SOC is charged first among the main battery 53 and the auxiliary battery 54, so that the SOC values are the same. After that, it will be charged at the same time. That is, for example, if the SOC of the auxiliary battery 54 has decreased at the time of battery separation, the battery control unit 13 turns ON the relays 93, 93 that connect the external charger 100 and the auxiliary battery 54, and then (See FIG. 8), after the SOC value of the auxiliary battery 54 becomes approximately the same as the SOC value of the main battery 53, the relays 91, 91 between the main battery 53 and the auxiliary battery 54 are turned on. (See Figure 9). Further, for example, if the SOC of the main engine battery 53 has decreased at the time of battery separation, the battery control unit 13 turns ON the relays 92, 92 that connect the external charger 100 and the main engine battery 53 (see Fig. 10), after the SOC value of the main engine battery 53 becomes approximately the same as the SOC value of the auxiliary equipment battery 54, the relays 91, 91 between the main engine battery 53 and the auxiliary equipment battery 54 are turned on (see Figure 10). (see 11).

The SOH estimating unit 14 acquires the peak shape of the discharge curve through discharge control for the secondary battery 22 which has been determined to function only as an auxiliary battery due to the disconnection control by the battery control unit 13, and based on the peak shape, Estimate the deterioration state of multiple secondary batteries. Specifically, the SOH estimating unit 14 identifies data that matches information on the temperature and C rate of the secondary battery 22, which are charge/discharge conditions, and has a similar peak shape, from among the on-board data in the storage unit 11. However, the deterioration state of the data is regarded as the deterioration state of the secondary battery 22, which functions only as an auxiliary battery. The secondary battery 22 that functions only as an auxiliary battery also supplies power integrally with other secondary batteries 22 (that is, the secondary battery 22 that functions as a driving battery) before separation. The deterioration state of the secondary battery 22, which functions only as an auxiliary battery, can be estimated to be the deterioration state of the secondary battery 22, which functions as a drive battery. In this manner, the SOH estimation unit 14 estimates the deterioration state of the secondary battery 22 that functions as a drive battery by deriving the deterioration state of the secondary battery 22 that functions only as an auxiliary battery after separation.

Next, a diagnostic process (diagnosis method) for a secondary battery according to this embodiment will be described with reference to FIG. 12. FIG. 12 is a flowchart showing a diagnostic process (diagnosis method) for a secondary battery.

As shown in FIG. 12, in the diagnostic system 10, SOC values are first obtained for a plurality of secondary batteries 22 that are configured to be separable from each other and function as a vehicle drive battery and an auxiliary battery. (Step S1).

Then, in the diagnostic system 10, based on the acquired SOC value, it is determined whether or not the plurality of secondary batteries 22 are in a state where the peak shape of the differential curve of the discharge curve can be acquired by discharge control (step S2). If it is determined in step S2 that it cannot be obtained, the subsequent processing is not performed (the plurality of secondary batteries remain integrated).

On the other hand, if it is determined in step S2 that acquisition is possible, the diagnostic system 10 causes some of the secondary batteries 22 included in the plurality of secondary batteries 22 to function only as auxiliary equipment batteries. , separation (separation control) of the plurality of secondary batteries 22 is performed (step S3).

Then, in the diagnostic system 10, a differential curve of a discharge curve is derived by discharge control for some of the secondary batteries 22 that are to function as the auxiliary battery 54 (step S4). Finally, the diagnostic system 10 acquires the peak shape of the derived differential curve, and estimates the deterioration state of the plurality of secondary batteries 22 based on the peak shape (step S5).

Next, the effects of the secondary battery diagnostic system 10 according to this embodiment will be explained.

A secondary battery diagnostic system 10 according to the present embodiment acquires SOC values for a plurality of secondary batteries 22 that function as a vehicle drive battery and an auxiliary battery and are configured to be separable from each other. Based on the SOC value acquired by the unit 12 and the acquisition unit 12, it is determined whether or not the plurality of secondary batteries 22 are in a state in which the peak shape of the differential curve of the discharge curve can be acquired by discharge control. When the peak shape can be acquired, the plurality of secondary batteries 22 are controlled to be separated so that some of the secondary batteries 22 included in the plurality of secondary batteries 22 function only as auxiliary equipment batteries. The peak shape of the differential curve of the discharge curve is obtained by the discharge control for the battery control unit 13 and some of the secondary batteries 22 that are now functioning only as auxiliary batteries due to the disconnection control, and based on the peak shape , and an SOH estimation unit 14 that estimates the deterioration state of the plurality of secondary batteries 22.

According to the diagnostic system 10 according to the present embodiment, it is determined that the plurality of secondary batteries 22 functioning as the drive battery and the auxiliary battery of the vehicle are in a state where the peak shape of the differential curve can be obtained. In this case, separation control of the plurality of secondary batteries 22 is performed so that some of the secondary batteries 22 included in the plurality of secondary batteries 22 function only as auxiliary equipment batteries. In this diagnostic system 10, the peak shape of the differential curve is acquired for some of the secondary batteries 22 that have been separated and now function only as auxiliary batteries, and the deterioration state of the plurality of secondary batteries 22 is determined. Presumed. In order to obtain the peak shape with high precision, it is necessary to perform discharge control in a low and constant current state. Moreover, it is difficult to perform discharge control in a constant current state. In this regard, in the diagnostic system 10 according to the present embodiment, when a part of the secondary battery 22, which normally serves as a drive battery and an auxiliary battery, is in a state where the peak shape of the differential curve can be obtained. In addition, it functions only as a battery for auxiliary equipment. Unlike the driving battery, the auxiliary equipment battery tends to maintain a low current and constant current state even when the auxiliary equipment performs normal operation. By acquiring the peak shapes of some of the secondary batteries 22 that are in a constant current state, the peak shapes of the differential curves of some of the secondary batteries 22 can be acquired with high precision. . Some of the secondary batteries 22 are included in the plurality of secondary batteries 22 before being separated, and are used as a driving battery and an auxiliary battery together with other secondary batteries included in the plurality of secondary batteries 22. Since it was functioning, it is considered that the deterioration state was the same as that of other secondary batteries 22 included in the plurality of secondary batteries 22. Therefore, by estimating the deterioration states of the plurality of secondary batteries 22 based on the peak shapes of some of the secondary batteries 22, the deterioration states of the plurality of secondary batteries 22 can be estimated with high accuracy. As described above, according to the diagnostic system 10 according to the present embodiment, the deterioration state of the secondary battery 22 can be appropriately diagnosed during driving.

In a state where some of the secondary batteries 22 are disconnected and function only as auxiliary batteries, the battery control unit 13 controls the discharge control so that some of the secondary batteries 22 have a peak shape of a differential curve of a discharge curve. If it is not possible to obtain the secondary batteries 22, some of the secondary batteries 22 are integrated with other secondary batteries 22 included in the plurality of secondary batteries 22, and the plurality of secondary batteries 22 are used as driving batteries and auxiliary equipment. It may function as a battery for use. According to such a configuration, when some of the secondary batteries 22 that have been separated for deterioration state estimation are not in a state where the peak shape can be obtained (not in such an SOC state), the relevant Some of the secondary batteries 22 can be appropriately integrated with other secondary batteries 22, and a plurality of secondary batteries 22 can be prevented from being senselessly separated.

DESCRIPTION OF SYMBOLS 10... Diagnosis system, 12... Acquisition part, 13... Battery control part, 14... SOH estimation part, 22... Secondary battery.

Claims (2)

an acquisition unit that acquires SOC values for a plurality of secondary batteries that function as a vehicle drive battery and an auxiliary battery and are configured to be separable from each other;
Based on the SOC value acquired by the acquisition unit, it is determined whether the plurality of secondary batteries are in a state where the peak shape of the differential curve of the charge/discharge curve can be acquired by charge/discharge control, and the peak shape is determined. battery control that performs separation control of the plurality of secondary batteries so that some of the secondary batteries included in the plurality of secondary batteries function only as the auxiliary equipment batteries when the battery is in a state where it is possible to obtain the battery; Department and
For some of the secondary batteries that have come to function only as the auxiliary battery due to the disconnection control, the peak shape of the differential curve of the charge/discharge curve is obtained by the charge/discharge control, and based on the peak shape, the A diagnostic system for a secondary battery, comprising: an estimation unit that estimates a deterioration state of a plurality of secondary batteries. The battery control unit is configured to control, in a state where the part of the secondary battery is separated and functioning only as the auxiliary battery, the part of the secondary battery is controlled to control a differential curve of a charge/discharge curve by charge/discharge control. If it is not possible to obtain the peak shape of The diagnostic system according to claim 1, wherein the diagnostic system functions as a battery for the auxiliary equipment.

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