JP2016081638A - Battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve determination accuracy of a deteriorated condition of a battery.SOLUTION: A battery system 100 includes a temperature sensor 156 for measuring a temperature TB of a battery cell 101 and an ECU 300 for determining a deteriorated condition of a battery pack 10 on the basis of a measurement result of the temperature sensor 156. The ECU 300 acquires the battery temperature TB, and when the battery temperature TB is included within a predetermined low temperature region and a temperature variation per unit time of the battery exceeds a predetermined value, calculates damage quantity to the battery cell 101 on the basis the temperature variation per unit time by using correlation (a curve C) between the temperature variation per unit time and the number of changes of the battery temperature TB up to a defective condition of the battery cell 101. The ECU 300, when an integrated value Z of the damage quantities exceeds a predetermined criterion value Zc, determines deterioration of the battery pack 10.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a battery system, and more particularly to a battery system that determines a deterioration state of a battery.

  When battery deterioration progresses, it is desirable to limit charging / discharging of the battery or notify the user to replace the deteriorated battery. Therefore, various techniques relating to the determination of the deterioration state of the battery have been proposed. For example, Japanese Patent Laying-Open No. 2012-127938 (Patent Document 1) discloses a battery deterioration monitoring method that performs an operation for calculating the amount of damage to a battery based on the charging current value, charging time, and battery temperature of the battery.

JP 2012-127938 A

  Sealed batteries have a pressure-resistant member that receives the pressure (internal pressure) of gas accumulated inside the battery, and includes a welded part between the case and the lid, a seal part, or a pressure-type current interrupt device (CID: Current Interrupt Device). Prepare.

  When the battery temperature of the sealed battery increases, the internal pressure increases and the pressure-resistant member and its peripheral members expand. On the other hand, when the battery temperature decreases, the internal pressure decreases and the pressure-resistant member and its peripheral members contract. . When stress (stress) due to expansion and contraction accompanying the change in internal pressure is applied to the pressure resistant member, the damage due to the stress is accumulated in the pressure resistant member, so that deterioration of the battery can proceed. However, Patent Document 1 does not disclose the possibility of battery deterioration due to a change in internal pressure, and therefore does not disclose a specific determination method for the deterioration state of the battery due to a change in internal pressure. Therefore, there is room for improvement in the determination accuracy of the deterioration state of the battery.

  The present inventors pay attention to the fact that the battery is greatly deteriorated when the battery temperature is within a predetermined low temperature range (for example, a temperature range of 0 ° C. or lower) and a sudden temperature change of a certain level or more occurs. The present inventors have found a method for determining the deterioration state of a battery due to a change in internal pressure.

  The present invention has been made to solve the above-described problems, and an object thereof is to improve the determination accuracy of the deterioration state of the battery.

  A battery system according to an aspect of the present invention includes a temperature sensor that measures the temperature of the battery, and a determination device that determines the deterioration state of the battery based on the measurement result of the temperature sensor. The determination device acquires the temperature of the battery, and when the acquired battery temperature is within a predetermined low temperature range and the temperature change amount per unit time of the battery exceeds a predetermined value, the temperature change amount per unit time The amount of damage to the battery is calculated based on the amount of temperature change per unit time using the correlation between the temperature change count of the battery until the battery reaches a defective state. The determination device further determines that the battery has deteriorated when the integrated value of the damage amount exceeds a predetermined reference value.

  When the amount of change in temperature per unit time of the battery (in other words, the amount of change in internal pressure per unit time) exceeds a predetermined value, deterioration of the pressure-resistant member due to the change in internal pressure tends to proceed. Further, if the low temperature region is appropriately determined according to the material of the pressure member, the deterioration of the pressure member due to the change in internal pressure is more likely to proceed in the low temperature region than in the high temperature region. Therefore, according to the above configuration, when the battery temperature obtained using the temperature sensor is in the low temperature range and the temperature change amount per unit time of the battery exceeds a predetermined value, the temperature change amount per unit time Based on the above, the amount of damage to the battery is calculated. In this calculation, a correlation between the amount of change in temperature per unit time and the number of changes in battery temperature until the battery reaches a defective state (for example, a state where battery replacement is required) is used. Thus, by considering the deterioration of the pressure-resistant member due to the change in internal pressure, it is possible to improve the determination accuracy of the deterioration state of the battery.

  ADVANTAGE OF THE INVENTION According to this invention, the determination precision of the deterioration state of a battery can be improved.

It is a block diagram which shows roughly the structure of the vehicle carrying the battery system which concerns on this Embodiment. FIG. 2 is a perspective view schematically showing a configuration of the power storage device shown in FIG. 1. It is a perspective view which shows the structure of the battery cell shown in FIG. It is an enlarged view of the cover part of the battery cell shown in FIG. It is a figure for demonstrating the calculation method of the damage amount to a battery pack. It is a flowchart for demonstrating the determination process of the deterioration state of the battery pack in this Embodiment. It is a figure for demonstrating the setting method of the reference value with respect to an integrated damage amount. It is a figure which shows the result of the vehicle running test at the time of using the reference value set based on the evaluation test result shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  In the embodiment described below, a configuration mounted on an electric vehicle will be described as an example of a battery system. However, the use of the battery system according to the present invention is not limited to vehicles.

<Overall configuration of vehicle>
FIG. 1 is a block diagram schematically showing the configuration of a vehicle equipped with a battery system according to the present embodiment. Referring to FIG. 1, a vehicle 1 includes a battery system 100, a system main relay (SMR) 210, a power control unit (PCU) 220, and a motor generator (MG). 230 and drive wheels 240. Battery system 100 includes a power storage device 150, a voltage sensor 152, a current sensor 154, a temperature sensor 156, and a control device (ECU: Electronic Control Unit) 300.

  Power storage device 150 is electrically connected to PCU 220 via SMR 210. The power storage device 150 is a DC power source configured to be chargeable / dischargeable, and typically includes a secondary battery such as a lithium ion battery or a nickel metal hydride battery, or a capacitor such as an electric double layer capacitor. In this embodiment, an example in which a lithium ion battery is employed will be described. The power storage device 150 supplies power for generating the driving force of the vehicle 1 to the PCU 220 when the vehicle 1 travels, and stores power generated by the MG 230 during regenerative braking of the vehicle 1.

  SMR 210 is electrically connected to a path connecting power storage device 150 and PCU 220. SMR 210 switches between electrical connection and disconnection between power storage device 150 and PCU 220 based on a control signal from ECU 300.

  PCU 220 is electrically connected to MG 230 and power storage device 150 via SMR 210. PCU 220 includes, for example, an inverter and a three-phase inverter. PCU 220 converts the discharge power from power storage device 150 into power for driving MG 230 based on a control signal from ECU 300. The PCU 220 can also convert the power supplied from the MG 230 into power for charging the power storage device 150.

  MG 230 is electrically connected to PCU 220 and coupled to drive wheel 240. MG230 is, for example, a three-phase AC rotating electric machine in which a permanent magnet is embedded in a rotor. The MG 230 receives the power supplied from the PCU 220 and generates a driving force for driving the vehicle 1. In addition, MG 230 receives the rotational force from drive wheel 240 and generates AC power, and generates a regenerative braking force in response to a regenerative torque command from ECU 300.

  Voltage sensor 152 detects voltage VB of power storage device 150. Current sensor 154 detects current IB input to and output from power storage device 150. Temperature sensor 156 detects temperature TB of power storage device 150. Each sensor outputs the detection result to ECU 300. ECU 300 calculates the SOC (State Of Charge) of power storage device 150 based on the detection results of each sensor, and controls SMR 210 and PCU 220 according to the calculation results. ECU 300 determines the deterioration state of power storage device 150 based on the detection result of temperature sensor 156. This determination method will be described later in detail.

  ECU 300 includes a CPU (Central Processing Unit), a memory, and a buffer (all not shown). ECU 300 executes arithmetic processing using signals from each sensor based on a map and a program stored in the memory, and outputs a control signal corresponding to the arithmetic processing result. Note that these controls are not limited to software processing, and may be hardware processing by a dedicated electronic circuit. The ECU 300 corresponds to the “determination device” according to the present invention.

<Configuration of power storage device>
FIG. 2 schematically shows a configuration of power storage device 150 shown in FIG. Referring to FIG. 2, power storage device 150 includes battery pack 10. In general, an in-vehicle power storage device often employs a battery pack including about several tens to 100 battery cells. Therefore, FIG. 2 shows a configuration in which 30 battery cells 101 to 130 are arranged, but the number of battery cells in the battery pack 10 is not particularly limited.

  Although not shown, the battery pack 10 is provided with a blower mechanism for cooling the battery cells 101 to 130. The air sent from the blower mechanism to the battery cells 101 to 130 circulates along the arrangement direction of the battery cells 101 to 130 as indicated by arrows AR1 and AR2. Thereby, each battery cell in the battery pack 10 is cooled.

  In the battery pack configured as described above, the cooling effect on the battery cell provided on the intake side (indicated by the arrow AR1) of the air blowing mechanism is more effective than the battery cell provided on the exhaust side (indicated by the arrow AR2). Higher than the cooling effect. In other words, the battery cell (for example, battery cell 101) provided on the upstream side of the air flow has a larger amount of temperature change than the battery cell (for example, battery cell 130) provided on the downstream side. Therefore, deterioration due to temperature change is most likely to occur in the most upstream battery cell 101 among all the battery cells 101 to 130 in the battery pack 10. Therefore, the temperature sensor 156 (see FIGS. 1 and 3) is preferably provided in the battery cell 101. This is because the deterioration of the battery pack 10 can be reliably detected before the deterioration of the other battery cells 102 to 130 proceeds excessively.

  Hereinafter, the configuration of the battery cell 101 will be described representatively. The configuration of the other battery cells 102 to 130 is the same as the configuration of the battery cell 101 except that the temperature sensor 156 is not provided.

  3 is a perspective view showing the configuration of the battery cell 101 shown in FIG. With reference to FIG. 3, the battery cell 101 is a sealed cell in which the case 21 is sealed by a lid portion 22. The case 21 and the lid portion 22 are joined by laser welding at a welded portion 221 along the outer periphery of the lid portion 22. In the present embodiment, a configuration in which an aluminum-based metal material such as an aluminum alloy is employed as the material of the case 21 and the lid portion 22 will be described.

  4 is an enlarged view of the lid portion 22 of the battery cell 101 shown in FIG. Referring to FIGS. 3 and 4, the lid portion 22 is provided with a positive electrode terminal 23 and a negative electrode terminal 24 each having a substantially rectangular parallelepiped shape. The positive terminal 23 includes a terminal plate 231 and a bolt 232. Although not shown, a pressure type current interrupt device (CID: Current Interrupt Device) is provided below the positive electrode terminal 23 (in the negative direction of the z-axis in the figure), and the terminal plate 231 is disposed above the CID. Serves as a lid. A wiring 233 for transmitting the voltage of the battery cell 101 is electrically connected to the bolt 232. The configuration of the negative electrode terminal 24 is different from the configuration of the positive electrode terminal 23 in that no CID is provided, but the other configuration is the same as the configuration of the positive electrode terminal 23, and thus detailed description will not be repeated.

  Although not shown in the figure, an electrode body in which a positive electrode and a negative electrode are wound through a separator is accommodated in the case 21 together with an electrolytic solution. When the electrolyte is decomposed and the gas is generated with the increase in the number of charge / discharge cycles or the passage of time, the gas is accumulated in the case 21. The lid portion 22 is further provided with a discharge valve 25 for discharging excess gas accumulated in the case 21.

  Next, the installation location of the temperature sensor 156 (156A, 156B) will be described. The present inventors performed a pressure resistance test (a test for examining the internal pressure and the fracture location when a weld is fractured by gradually feeding gas from the outside to the interior of the battery cell 101). As a result, it has been found that among the welded portions 221 along the outer periphery of the lid portion 22, the short-side welded portion 23 </ b> A of the positive electrode terminal 23 or the short-side welded portion 24 </ b> A of the negative electrode terminal 24 is likely to break.

  Based on this test result, in the present embodiment, a temperature sensor 156A is provided at the welded portion 23A of the positive electrode terminal 23, and a temperature sensor 156B is provided at the welded portion 24A of the negative electrode terminal 24. Thus, by providing a temperature sensor at a place where breakage is most likely to occur and measuring the temperature accurately, the determination accuracy of the deterioration state is improved, so that breakage can be reliably prevented. Output signals from temperature sensors 156A and 156B are transmitted to ECU 300 via wires 234 and 244, respectively. In addition, it is not an essential structure to provide the temperature sensor in two places, but only one place or three or more places may be provided.

  Here, in a state where gas is accumulated in the case 21, the pressure (internal pressure) in the case 21 changes as the battery temperature TB changes. When the internal pressure rises, the case 21 and the lid portion 22 expand to apply stress (stress) to the welded portion 221. On the other hand, even when the internal pressure decreases, the case 21 and the lid portion 22 contract, and stress is applied to the welded portion 221. When such stress is repeatedly applied to the welded part 221, damage due to the stress is accumulated in the welded part 221, and eventually the welded part 221 (particularly the welded parts 23A and 24A) may be broken.

  Regarding the determination of the deterioration state of the battery, various techniques have been proposed like the deterioration monitoring method disclosed in Patent Document 1 described above. However, the possibility of deterioration due to a change in internal pressure of a pressure-resistant member such as a welded part has not been considered in the past. In order to improve the determination accuracy of the deterioration state of the battery, it is desirable to perform deterioration determination more comprehensively taking into account deterioration due to a change in internal pressure as one of deterioration factors.

  Therefore, the present inventors have a high temperature in a predetermined low temperature range (temperature range of 0 ° C. or lower in the present embodiment) determined according to the material of the welded portion 221 (in this embodiment, an aluminum-based metal material). Compared to the region (temperature region higher than 0 ° C.), the pressure-resistant member is more likely to deteriorate due to the change in internal pressure, and the amount of change in battery temperature TB per unit time (in other words, the amount of change in internal pressure per unit time) When the value exceeds a predetermined value, attention was paid to the point that the deterioration of the pressure-resistant member due to the change in internal pressure tends to proceed.

  More specifically, in general, the strength of an aluminum-based metal material increases in a low temperature region. On the other hand, in the state where members having different shapes are welded (particularly, the state where the lid portion 22 and the case 21 are welded at approximately 90 ° as shown in FIG. 4), the present inventors It has been found that when the stress due to the internal pressure fluctuation caused by the change in the temperature TB is applied to the welded part 221, the battery cell 101 is likely to deteriorate.

  Then, the present inventors digitize the amount of damage to the welded part 221 according to the amount of change in the battery temperature TB per unit time under the low temperature region and the number of times of change, thereby deteriorating the battery cell 101. I found a method to judge. Thus, by considering the deterioration of the welded part 221 due to the change in internal pressure, it is possible to improve the determination accuracy of whether or not the battery pack 10 is deteriorated.

<Method for determining the deterioration state of the battery pack>
FIG. 5 is a diagram for explaining a method for calculating the amount of damage to the battery pack 10. In FIG. 5, the vertical axis represents an absolute value (hereinafter abbreviated as a change rate) ΔT of a change amount of the battery temperature TB per unit time (for example, one hour). The horizontal axis indicates the number of changes in the battery temperature TB, that is, the number of damages to the welded part 221 due to changes in internal pressure. As an example, when the battery temperature TB = 0 ° C. changes to the battery temperature TB = 30 ° C. after 1 hour, the change rate ΔT = 30 (unit: ° C./h) is calculated.

  Referring to FIGS. 4 and 5, curve C shows the relationship between the number of damages and change rate ΔT until welded part 221 breaks and battery pack 10 reaches a defective state. More specifically, in the case of damage at the change rate ΔT = T1, when the number of damages reaches, for example, 80 times, the battery pack 10 can reach a defective state. Similarly, in the case of damage at a change rate ΔT = T2 (<T1), when the number of damages reaches, for example, 100 times, the battery pack 10 may be in a defective state. On the other hand, when the change rate ΔT is damage less than T0 (for example, 20 ° C./h), the battery pack 10 is unlikely to be in a defective state regardless of the number of damages.

  The curve C may be obtained by simulation based on the design data of the battery pack 10 and the battery cell 101, or may be obtained experimentally based on the evaluation test result. The relationship shown in FIG. 5 corresponds to the “correlation” according to the present invention.

  According to the present embodiment, the amount of damage to the battery pack 10 is quantified using the curve C. That is, the amount of damage when the stress at the change rate T1 is applied 80 times is defined as 100. Therefore, the damage amount ΔZ per time of the stress at the change rate T1 is calculated as ΔZ = 1/80 × 100 = 1.25. Similarly, the amount of damage when the stress at the change rate T2 is applied 100 times is defined as 100. Therefore, the damage amount ΔZ per time of the stress at the change rate T2 is calculated as ΔZ = 1/100 × 100 = 1.00.

  Since the damage amount ΔZ is accumulated in the welded part 221, the integrated damage amount Z is calculated by integrating the damage amount ΔZ. As an example, when the stress at the change rate T1 is applied 8 times and the stress at the change rate T2 is applied 30 times separately, the integrated damage amount Z of the battery pack 10 is Z = (1.25 × 8) + (1.00 × 30) = 10.0 + 30.0 = 40.0 is calculated.

  Based on the integrated damage amount Z thus calculated, the deterioration state of the battery cell 101 is determined. When the integrated damage amount Z is less than the predetermined reference value Zc, it is determined that the battery cell 101 has not deteriorated. On the other hand, when the integrated damage amount Z is greater than or equal to the reference value Zc, the battery cell 101 has deteriorated. It is determined that

  FIG. 6 is a flowchart for explaining the determination process of the deterioration state of battery cell 101 in the present embodiment. This flowchart is called and executed from the main routine at predetermined time intervals, for example. Each step included in this flowchart is basically realized by software processing by ECU 300, but may be realized by dedicated hardware created in ECU 300.

  A count value indicating the number of damages at each change speed ΔT is stored in a memory (not shown) of ECU 300. That is, as described above, since the number of damages at the change rate ΔT = T1 and the number of damages at the change rate ΔT = T2 need to be counted separately, a count value is provided for each change rate ΔT. Each count value is set to an initial value of 0 when a new battery pack 10 is mounted (or replaced).

  Referring to FIG. 6, in step (hereinafter abbreviated as “S”) 10, ECU 300 determines whether or not trip of vehicle 1 has started. The trip means a period from when an unillustrated ignition switch provided in the vehicle 1 is turned on (IG-ON) to when an off operation (IG-OFF) is performed.

  When the trip is not started, that is, in the IG-OFF state (NO in S10), ECU 300 skips the subsequent processes and ends the series of processes. On the other hand, when the trip is started, that is, in the IG-ON state (YES in S10), ECU 300 advances the process to S20 in order to calculate the amount of damage to battery pack 10.

  In S20, ECU 300 acquires a measured value of battery temperature TB from temperature sensor 156 (156A, 156B), and stores the measured value in a memory. Further, ECU 300 calculates change rate ΔT of battery temperature TB using a measured value of battery temperature TB acquired and stored in a memory before a unit time (for example, one hour).

  In S30, the ECU 300 determines whether or not the battery temperature TB newly acquired in S20 is in a low temperature region of −30 ° C. or higher and 0 ° C. or lower. When battery temperature TB is −30 ° C. or higher and 0 ° C. or lower (YES in S30), ECU 300 advances the process to S40.

  The lower limit value (−30 ° C.) of the low temperature region is set because the use of the vehicle 1 in the temperature region below −30 ° C. is not assumed, and is −30 ° C. according to the specification of the vehicle 1. A smaller value may be set. On the other hand, the upper limit value (0 ° C.) of the low temperature region is preferably determined theoretically or experimentally according to the material of the case 21 and the lid portion 22, the welding mode of the welded portion 221, and the like.

  In S40, ECU 300 determines whether or not change speed ΔT calculated in S20 is greater than T0. When change speed ΔT is greater than T0 (YES in S40), ECU 300 increments the count value of the number of damages corresponding to the change speed ΔT (S50).

  On the other hand, when battery temperature TB is less than −30 ° C. or higher than 0 ° C. (NO in S30), or when change rate ΔT is T0 or less (NO in S40), ECU 300 does not increment the count value. The process returns to S20.

  Until the trip is completed (NO in S60), the processes of S20 to S60 are repeated at a predetermined time interval (for example, one minute interval). When the trip ends (YES in S60), ECU 300 calculates damage amount ΔZ in the trip (S70). Since this calculation method has been described in detail with reference to FIG. 5, description thereof will not be repeated here. Further, the ECU 300 reads the integrated damage amount Z stored in the memory until the end of the previous trip, and updates the integrated damage amount Z by adding the damage amount ΔZ in the trip calculated in S70 ( Z = Z + ΔZ) (S80).

  In S90, the ECU 300 determines whether or not the integrated damage amount Z is equal to or greater than the reference value Zc. In order to accurately determine the deterioration state of battery pack 10, it is desirable to set reference value Zc to an appropriate value. However, as will be described later with reference to FIGS. Then, the reference value Zc = 100 is set. When integrated damage amount Z is less than reference value Zc (NO in S90), ECU 300 assumes that battery pack 10 has not deteriorated, stores integrated damage amount Z in the memory in a nonvolatile manner, and ends a series of processes. .

  On the other hand, when integrated damage amount Z is equal to or greater than reference value Zc (YES in S90), ECU 300 determines that battery pack 10 has deteriorated, generates a diagnosis indicating abnormality of battery pack 10, and causes battery pack 10 to be removed. Notify the user to exchange. The notification method to the user is not particularly limited. For example, the ECU 300 displays a message prompting the user to bring the vehicle 1 to the dealer and request replacement of the battery pack 10 on a display unit (not shown). Let In addition, ECU 300 may control PCU 220 so as to perform retreat travel in which charging / discharging of battery pack 10 is restricted as compared with normal travel at the next IG-ON. Thereafter, ECU 300 ends a series of processes.

  In the flowchart shown in FIG. 6, the processing for updating the integrated damage amount Z after the end of the trip has been described, but the timing for updating the integrated damage amount Z is not particularly limited. The integrated damage amount Z may be updated every elapse of a predetermined period or every predetermined travel distance.

  FIG. 7 is a diagram for explaining a method for setting the reference value Zc of the integrated damage amount Z. With reference to FIGS. 4 and 7, as a result of the evaluation test conducted by the present inventors, when the integrated damage amount Z is 100 or less, the fracture of the welded part 221 (welded part 23A, 24A) is not confirmed. It was. On the other hand, the fracture of the welded part 221 was confirmed when the integrated damage amount Z was 103 or more. From this test result, it is understood that the reference value Zc of the integrated damage amount Z is preferably set to a numerical value range of 100 or more and less than 103. Therefore, in the present embodiment, an example in which the reference value Zc = 100 is set will be described.

  FIG. 8 is a diagram showing the results of a vehicle running test when using a reference value Zc (= 100) set based on the evaluation test results shown in FIG. In this vehicle running test, when the integrated damage amount Z reaches the reference value Zc, a configuration is adopted in which traveling of the vehicle 1 is prohibited in order to avoid a further increase in the integrated damage amount Z. Three battery packs 10 were prepared as samples, and the number of running tests was N = 3. On the other hand, FIG. 8 also describes a configuration in which traveling is not prohibited even when the integrated damage amount Z reaches the reference value Zc as a comparative example.

  In the comparative example, even if the cumulative damage amount Z reaches the reference value Zc = 100, traveling is not prohibited, so the use of the battery pack 10 is continued and the cumulative damage amount Z exceeds 100. As a result, when the integrated damage amount Z reached 105, the welded part 221 was broken.

  On the other hand, according to the present embodiment, when the cumulative damage amount Z reaches 100, a diagnosis indicating an abnormality of the battery pack 10 occurs, and the vehicle 1 is prohibited from traveling at the next IG-ON. By doing so, since further increase in the integrated damage amount Z is avoided, the welded part 221 did not break in any of the three running tests. As described above, according to the result of the running test, the reference value Zc is appropriately set based on the evaluation test result (see FIG. 7) so as to ensure a sufficient margin before the welded portion 221 breaks. Thus, it was confirmed that breakage of the welded part 221 can be prevented.

  The determination process of the deterioration state of the battery pack 10 described with reference to FIGS. 5 and 6 is not limited to the welded portion 221 and can be similarly applied to other pressure-resistant members that can be deteriorated with a change in internal pressure. For example, the present invention can also be applied to the determination of the deterioration state of the discharge valve 25 (see FIG. 4) and CID (not shown) for discharging gas. In this case, as the reference value Zc, it is preferable to set a value corresponding to the pressure-resistant member separately.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Vehicle, 10 Battery pack, 100 Battery system, 101-130 Battery cell, 150 Power storage device, 152 Voltage sensor, 154 Current sensor, 156, 156A, 156B Temperature sensor, 21 Case, 22 Lid part, 23 Positive electrode terminal, 24 Negative electrode Terminals, 231 and 241 Terminal boards, 232 and 242 bolts, 233, 234, 243 and 244 wiring lines, 210 system main relay (SMR), 220 power control unit (PCU), 230 motor generator (MG), 240 drive wheels, 300 Control unit (ECU).

Claims (1)

A battery system for determining a deterioration state of a battery,
A temperature sensor for measuring the temperature of the battery;
A determination device for determining a deterioration state of the battery based on a measurement result of the temperature sensor;
The determination device includes:
Obtain the temperature of the battery,
When the obtained temperature of the battery is within a predetermined low temperature range and the temperature change amount per unit time of the battery exceeds a predetermined value, the temperature change amount per unit time and the battery are in a defective state. Using the correlation with the number of temperature changes of the battery until the calculated amount of damage to the battery based on the amount of temperature change per unit time,
The battery system which determines with the said battery having deteriorated when the integrated value of the said damage amount exceeds a predetermined reference value.

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