JP2018080969A - Lithium ion secondary battery control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control system capable of determining the degradation of a lithium ion secondary battery, with which it is possible to determine degradation without limiting the timing of degradation determination and also determine the cause of degradation when degradation abnormality is found.SOLUTION: An ECU 100 estimates the resistance increase rate of a cell on the basis of a temperature T of the cell. When the result of this estimation is different from the calculation result of a resistance increase rate based on a current I and a voltage V, the ECU 100 determines that there is occurrence of degradation abnormality. Furthermore, when it is determined that there is occurrence of degradation abnormality, the ECU 100 determines, on the basis of the relative magnitudes of Δax1 and Δay1 and the relative magnitudes of Δbx1 and Δby2, whether there is increase in a DC resistance component or there is increase in a diffusive resistance component.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a control system for a lithium ion secondary battery.

  Japanese Patent Laying-Open No. 2015-129677 (Patent Document 1) discloses a secondary battery abnormality detection device capable of detecting cell deterioration. In this abnormality detection device, if the rate of change in resistance, which represents the rate of change from the initial value of the internal resistance of the cell, is equal to or higher than the determination value and the cell temperature is equal to or higher than the threshold value, the cell is determined to be abnormal. (See Patent Document 1).

Japanese Patent Laying-Open No. 2015-129677 JP2015-122910A JP 2014-153269 A

  In the abnormality detection device described in Patent Document 1, since the rate of change in resistance with respect to the initial value of the internal resistance of the cell is calculated, the SOC of the cell is adjusted to a predetermined value at a limited timing such as when the vehicle is stopped. It is necessary to acquire a resistance value by performing charging / discharging at. In addition, when it is determined that the cell is abnormally deteriorated, it is desirable that the deterioration factor (whether the DC resistance is increased or the diffusion resistance is increased) can also be determined.

  Therefore, an object of the present disclosure is to enable deterioration determination without limiting the timing of deterioration determination in a control system that can determine deterioration of a lithium ion secondary battery, and when it is determined that the deterioration is abnormal. It is also possible to determine the deterioration factor.

  A control system for a lithium ion secondary battery according to the present disclosure includes a detection device that detects the temperature, current, and voltage of the lithium ion secondary battery, and a control device. The control device uses a predetermined relationship between the temperature of the lithium ion secondary battery and the internal resistance increase rate indicating the deterioration rate of the lithium ion secondary battery, and determines the lithium ion secondary battery from the temperature detected by the detection device. Estimate the rate of increase in internal resistance. Then, the control device uses a predetermined relationship between the internal resistance increase rate and each increase rate of the DC resistance component and the diffusion resistance component indicating the component of the internal resistance to determine the DC resistance from the estimated value of the internal resistance increase rate. A first value indicating the component increase rate and a second value indicating the diffusion resistance component increase rate are estimated. In addition, the control device calculates a third value indicating the increase ratio of the DC resistance component and a fourth value indicating the increase ratio of the diffusion resistance component from the current and voltage change amount flowing in the lithium ion secondary battery. In the control device, when the difference between the first value and the third value or the difference between the second value and the fourth value is larger than a predetermined value, a deterioration abnormality of the lithium ion secondary battery has occurred. Judge that it is. When it is determined that the deterioration abnormality has occurred, the control device, when the first value is larger than the third value and the second value is smaller than the fourth value, When it is determined that a deterioration abnormality due to an increase in the diffusion resistance component has occurred, the first value is smaller than the third value, and the second value is larger than the fourth value, It is determined that a deterioration abnormality due to an increase in the DC resistance component has occurred.

  According to this control system, when the difference between the first value and the third value or the difference between the second value and the fourth value is larger than a predetermined value, the lithium ion secondary battery Therefore, it is possible to determine the deterioration without limiting the timing of the deterioration determination. Further, when it is determined that the deterioration abnormality has occurred, the diffusion resistance is determined based on the magnitude relationship between the first value and the third value and the magnitude relationship between the second value and the fourth value. It can be determined whether there is a deterioration abnormality accompanying the increase of the component or a deterioration abnormality accompanying the increase of the DC resistance component.

It is the figure which showed schematically the structure of the vehicle carrying the control system of the lithium ion secondary battery according to embodiment of this indication. It is a flowchart explaining the process sequence of the deterioration determination of the cell performed by ECU. It is a figure for demonstrating the 1st voltage variation | change_quantity and 2nd voltage variation | change_quantity of a cell when a fixed electric current flows. It is a flowchart explaining the calculation procedure of the estimated value of the resistance increase rate based on temperature information. It is the figure which showed an example of the relationship between the temperature of a cell, and the deterioration rate of a cell. It is a figure for demonstrating the method of determining a deterioration factor when deterioration abnormality has arisen.

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

  FIG. 1 is a diagram schematically illustrating a configuration of a vehicle 1 on which a control system for a lithium ion secondary battery according to an embodiment of the present disclosure is mounted. In the following, the case where the vehicle 1 is a hybrid vehicle will be described as a representative example. However, the battery system of the present disclosure is not limited to the one mounted on the hybrid vehicle, and is a general vehicle equipped with a lithium ion secondary battery. Furthermore, it is applicable to uses other than vehicles.

  Referring to FIG. 1, a vehicle 1 includes an assembled battery 10, a monitoring unit 20, a power control unit (hereinafter referred to as “PCU (Power Control Unit)”) 30, a motor generator (hereinafter referred to as “MG (Motor Generator)”. 41), 42, engine 50, power split device 60, drive shaft 70, drive wheel 80, and electronic control unit (hereinafter referred to as "ECU (Electronic Control Unit)") 100. Is provided.

  The engine 50 is an internal combustion engine that outputs motive power by converting combustion energy generated when an air-fuel mixture is burned into kinetic energy of a moving element such as a piston or a rotor. Power split device 60 includes, for example, a planetary gear mechanism having three rotation shafts of a sun gear, a carrier, and a ring gear. Power split device 60 divides the power output from engine 50 into power for driving MG 41 and power for driving drive wheels 80.

  MGs 41 and 42 are AC rotating electric machines, for example, three-phase AC synchronous motors in which permanent magnets are embedded in a rotor. The MG 41 is mainly used as a generator driven by the engine 50 via the power split device 60. The electric power generated by the MG 41 is supplied to the MG 42 or the assembled battery 10 via the PCU 30.

  The MG 42 mainly operates as an electric motor and drives the drive wheels 80. The MG 42 is driven by receiving at least one of the electric power from the assembled battery 10 and the electric power generated by the MG 41, and the driving force of the MG 42 is transmitted to the driving shaft 70. On the other hand, when the vehicle is braked or when acceleration is reduced on a downward slope, the MG 42 operates as a generator and performs regenerative power generation. The electric power generated by the MG 42 is supplied to the assembled battery 10 via the PCU 30.

  The assembled battery 10 includes a plurality of lithium ion secondary batteries (single cells) connected in series, and stores electric power for driving the MGs 41 and 42. That is, the assembled battery 10 can supply power to the MGs 41 and 42 through the PCU 30. The assembled battery 10 is charged by receiving generated power through the PCU 30 when the MGs 41 and 42 generate power.

  The monitoring unit 20 includes a voltage sensor 21, a current sensor 22, and a temperature sensor 23. The voltage sensor 21 detects the voltage V for each cell of the assembled battery 10. The current sensor 22 detects the charge / discharge current I of the assembled battery 10. The temperature sensor 23 detects the temperature T for each cell of the assembled battery 10. Each sensor outputs a signal indicating the detection result to ECU 100.

  Note that the voltage sensor 21 and the temperature sensor 23 may detect the voltage and temperature using a plurality of (for example, several) cells as monitoring units. In this case, for the voltage, the voltage (average value) for each cell can be calculated by dividing the detection values for a plurality of cells by the number of cells.

  The PCU 30 performs bidirectional power conversion between the assembled battery 10 and the MGs 41 and 42 in accordance with a control signal from the ECU 100. The PCU 30 is configured to be able to control the states of the MGs 41 and 42 separately. For example, the PCU 30 can set the MG 42 to a power running state while the MG 41 is in a regenerative (power generation) state. PCU 30 includes, for example, two inverters provided corresponding to MGs 41 and 42 and a converter that boosts a DC voltage supplied to each inverter to an output voltage of assembled battery 10 or higher.

  The ECU 100 includes a CPU (Central Processing Unit) 101, a memory (ROM (Read Only Memory) and RAM (Random Access Memory)) 102, and an input / output port (not shown) for inputting and outputting various signals. Consists of. The ECU 100 controls charging / discharging of the assembled battery 10 by controlling the PCU 30 and the engine 50 based on signals received from each sensor and various programs and maps stored in the memory 102.

  As main control executed by the ECU 100, the ECU 100 determines whether or not a deterioration abnormality has occurred in a lithium ion secondary battery (hereinafter also referred to as “cell” as appropriate) constituting the assembled battery 10. Do.

  Here, as for the cell deterioration abnormality determination, for example, a method for determining cell deterioration abnormality from a change in the OCV of the cell is also known. However, in such a method, basically, a battery such as when the vehicle is stopped is used. Since data can be acquired only when there is no input / output, the timing at which a deterioration abnormality can be determined is limited.

  Therefore, in vehicle 1 according to this embodiment, ECU 100 estimates an internal resistance increase amount (resistance increase rate) indicating the degree of cell degradation based on the history of cell temperature T. When the estimation result is different from the calculation result of the internal resistance increase amount (resistance increase rate) based on the current I and the voltage V, the ECU 100 determines that a cell deterioration abnormality has occurred.

  Furthermore, in vehicle 1 according to this embodiment, when ECU 100 determines that a deterioration abnormality has occurred, ECU 100 determines whether the deterioration factor is due to an increase in DC resistance (component resistance) or diffuse resistance. Determine if it is due to an increase or the like. Hereinafter, the cell deterioration determination method executed by the ECU 100 will be described in detail.

  FIG. 2 is a flowchart illustrating a processing procedure for cell deterioration determination executed by the ECU 100. The processing shown in this flowchart is executed for each cell constituting the assembled battery 10, but for some representative cells that are appropriately determined, such as the approximate center and end of the assembled battery 10. May be executed. Then, the processing shown in this flowchart is executed for each of the deterioration determination target cells when a substantially constant current I flows through the assembled battery 10.

  Referring to FIG. 2, ECU 100 obtains a detected value of current I from current sensor 22, and obtains a detected value of voltage V for the target cell for deterioration determination from voltage sensor 21. Then, the ECU 100 calculates a first voltage change amount ΔVy1 and a second voltage change amount ΔVy2 (described later) of the target cell due to the flow of a substantially constant current I, and acquires the acquired current I and the calculated first voltage change. Based on the amount ΔVy1 and the second voltage change amount ΔVy2, the first resistance increase rate Ry1 and the second resistance increase rate Ry2 of the target cell are calculated (step S10).

  FIG. 3 is a diagram for explaining the first voltage change amount ΔVy1 and the second voltage change amount ΔVy2 of the cell when a constant current flows. FIG. 3 shows how the voltage of the cell changes when a constant discharge current of I = I1 flows from a state where no current flows.

  Referring to FIG. 3, the horizontal axis indicates time t, and it is assumed that a constant current (discharge) of I = I1 flows from time 0 to time t1. The vertical axis represents the cell voltage V. As shown in FIG. 3, when the current I flows, the cell voltage changes in two steps. That is, in the initial stage where the current I begins to flow, the voltage V decreases rapidly (first voltage change amount ΔVy1), and then the voltage V decreases at a relatively slow rate (second voltage change amount ΔVy2). ).

  The first voltage change amount ΔVy1 indicating the voltage change in the initial stage is considered to indicate a voltage change (here, a voltage drop) due to a DC resistance (for example, 0.1 second resistance) component of the cell. On the other hand, the subsequent second voltage change amount ΔVy2 is considered to indicate a voltage change (voltage drop) due to a component such as a diffusion resistance (for example, a 10-second resistance) in the cell.

  Therefore, in this embodiment, the first resistance increase rate ΔRy1 indicating the increase rate of the DC resistance component is calculated from the first voltage change amount ΔVy1 and the current I, and the diffusion resistance is calculated from the second voltage change amount ΔVy2 and the current I. A second resistance increase rate ΔRy2 indicating the increase rate of the component is calculated.

  The first resistance increase rate ΔRy1 is calculated from the value obtained by dividing the first voltage change amount ΔVy1 by the current I and the value of the DC resistance component in the initial state of the target cell (for example, the state before product shipment or immediately after shipment). For example, a value obtained by dividing the first voltage change amount ΔVy1 by the current I is a value expressed as a percentage of the DC resistance component value in the initial state. Note that the DC resistance component value in the initial state is obtained in advance in the initial state of the cell and stored in the memory 102.

  Similarly, the second resistance increase rate ΔRy2 is calculated from the value obtained by dividing the second voltage change amount ΔVy2 by the current I and the value of the diffusion resistance component in the initial state of the target cell. For example, the second voltage change amount ΔVy2 Is a value expressed as a percentage of the DC resistance component value in the initial state. Note that the diffusion resistance component value in the initial state is also obtained in advance in the initial state of the cell and stored in the memory 102.

  Referring to FIG. 2 again, ECU 100 determines, based on first resistance increase rate ΔRy1 and second resistance increase rate ΔRy2 calculated in step S10, DC resistance component increase rate Δay1 and diffusion resistance component of the target cell. An increase rate Δby2 is calculated (step S20). The increase ratio Δay1 of the DC resistance component indicates the ratio of the DC resistance component in the increase in the resistance of the cell, the increase ratio Δby2 of the diffusion resistance component indicates the ratio of the diffusion resistance component in the increase in the resistance of the cell, and Δay1 + Δby2 = 1 (100%).

  The relationship between the first resistance increase rate ΔRy1 and the second resistance increase rate ΔRy2 and the DC resistance component increase rate Δay1 and the diffusion resistance component increase rate Δby2 is obtained in advance by experiments or the like for each current I and its energization time t. And stored as a map in the memory 102 of the ECU 100. Then, a map corresponding to the current I acquired in step S10 of FIG. 2 and its energization time t is selected, and using the map, the first resistance increase rate ΔRy1 and the second resistance increase rate calculated in step S10 of FIG. Based on the resistance increase rate ΔRy2, the DC resistance component increase rate Δay1 and the diffusion resistance component increase rate Δby2 in the target cell are obtained.

  Next, the ECU 100 acquires an estimated value ΔRx of the resistance increase rate based on the temperature information of the target cell (step S30). The estimated value ΔRx of the resistance increase rate based on this temperature information is always calculated in another subroutine.

  FIG. 4 is a flowchart for explaining the calculation procedure of the estimated value ΔRx of the resistance increase rate based on the temperature information. The processing shown in this flowchart is repeatedly executed at predetermined time intervals for each target cell for deterioration determination.

  Referring to FIG. 4, ECU 100 acquires a detected value of temperature T for the target cell for deterioration determination from temperature sensor 23 (step S210). Next, ECU 100 estimates cell degradation rate β (internal resistance increase rate) based on acquired temperature T (step S220).

  FIG. 5 shows an example of the relationship between the cell temperature T and the cell degradation rate β. In FIG. 5, the horizontal axis indicates the reciprocal of the temperature T, and the vertical axis indicates the natural logarithm of the deterioration rate β (internal resistance increase rate). As shown in the figure, the temperature dependence according to the Arrhenius side is understood with respect to the deterioration rate β (internal resistance increasing rate).

  Such a relationship between the cell temperature T and the deterioration rate β (internal resistance increase rate) is obtained in advance by experiments or the like and stored in the memory 102 of the ECU 100 as a map. Then, based on the temperature T of the target cell detected by the temperature sensor 23, the deterioration rate β (internal resistance increase rate) of the target cell is estimated.

  Referring to FIG. 4 again, ECU 100 integrates deterioration rate β (internal resistance increase rate) estimated in step S220, and calculates estimated value ΔRx of the resistance increase rate of the target cell from the integrated value (step S230). ). As described above, since the deterioration rate β is the internal resistance increase rate, the integrated value of the deterioration rate β indicates the internal resistance increase amount of the target cell. Therefore, the estimated value ΔRx of the resistance increase rate is calculated by dividing the value obtained by adding the integrated value of the deterioration rate β to the internal resistance value in the initial state of the target cell by the internal resistance value in the initial state. Can do.

  Referring to FIG. 2 again, when the estimated value ΔRx of the resistance increase rate based on the temperature information of the target cell is acquired in step S30, ECU 100 determines the direct current for the target cell from the acquired resistance increase rate estimated value ΔRx. The increase ratio Δax1 of the resistance component and the increase ratio Δbx1 of the diffusion resistance component are estimated (step S40).

  Regarding the estimation method of the DC resistance component increase rate Δax1 and the diffusion resistance component increase rate Δbx1, the relationship between the cell resistance increase rate and the DC resistance component increase rate and the diffusion resistance component increase rate is obtained in advance by experiments or the like. And stored as a map in the memory 102 of the ECU 100. Then, based on the estimated value ΔRx of the resistance increase rate acquired in step S30, the DC resistance component increase rate Δax1 and the diffusion resistance component increase rate Δbx1 are estimated using the above map. The DC resistance component increase rate Δax1 and the diffusion resistance component increase rate Δbx1 are also values having a relationship of Δax1 + Δbx1 = 1 (100%).

  In this embodiment, the DC resistance component increase rate Δay1 calculated in step S20 is compared with the DC resistance component increase rate Δax1 (estimated value based on temperature) calculated in step S40, and in step S20. The calculated diffusion resistance component increase rate Δby2 is compared with the diffusion resistance component increase rate Δbx1 (estimated value based on temperature) calculated in step S40. Then, based on the comparison result, it is determined whether or not a deterioration abnormality of the target cell has occurred. If the deterioration abnormality has occurred, a deterioration factor (deterioration abnormality accompanying an increase in the diffusion resistance component is detected). Whether it has occurred or whether there is a deterioration abnormality accompanying an increase in the DC resistance component).

  FIG. 6 is a diagram for explaining a method of determining a deterioration factor when a deterioration abnormality occurs. Referring to FIG. 6, the horizontal axis indicates the increase rate of the DC resistance component (for example, 0.1 second resistance), and the vertical axis indicates the increase rate of the diffusion resistance component (for example, 10 second resistance). When the increase rate Δay1 of the DC resistance component calculated based on the current I and the voltage V is larger than the increase rate Δax1 (estimation value based on the temperature) of the DC resistance component estimated based on the temperature information, the DC It is determined that abnormal deterioration has occurred due to an increase in resistance component (region indicated by “abnormal deterioration zone (DC resistance increase)” in FIG. 6).

  On the other hand, when the increase rate Δby2 of the diffusion resistance component calculated based on the current I and the voltage V is larger than the increase rate Δbx1 (estimation value based on the temperature) of the diffusion resistance component estimated based on the temperature information. Then, it is determined that abnormal deterioration has occurred due to an increase in the diffusion resistance component (region indicated by “abnormal deterioration zone (diffusion resistance increase)” in FIG. 6).

  As described above, since there is a relationship of Δax1 + Δbx1 = 1 (100%) and Δay1 + Δby2 = 1 (100%), when Δay1 is larger than Δax1 (abnormal deterioration zone due to increased DC resistance), Δby2 is It becomes smaller than Δbx1. When Δby2 is larger than Δbx1 (abnormal deterioration zone due to increased diffusion resistance), Δay1 is smaller than Δax1.

  Referring to FIG. 2 again, when step S40 is executed, ECU 100 determines the difference between the DC resistance component increase rate Δax1 estimated in step S40 and the DC resistance component increase rate Δay1 calculated in step S20. The difference (absolute value) between the increase ratio Δbx1 of the diffusion resistance component estimated in step S40 and the increase ratio Δby2 of the diffusion resistance component calculated in step S20 (absolute value) is equal to or less than the threshold value δ1. Is less than or equal to the threshold value δ2 (step S50).

  If it is determined that the difference (absolute value) between Δax1 and Δay1 is equal to or smaller than threshold value δ1, and the difference (absolute value) between Δbx1 and Δby2 is equal to or smaller than threshold value δ2 (YES in step S50). The ECU 100 ends the process without executing a series of subsequent processes.

  On the other hand, when it is determined in step S50 that the difference (absolute value) between Δax1 and Δay1 is larger than the threshold value δ1, or the difference (absolute value) between Δbx1 and Δby2 is larger than the threshold value δ2. (NO in step S50), ECU 100 determines that a deterioration abnormality has occurred in the target cell (step S60), and executes the following processing.

  That is, the ECU 100 determines that the increase rate Δax1 of the DC resistance component estimated based on the temperature information is larger than the increase rate Δay1 of the DC resistance component calculated based on the current I and the voltage V of the target cell, and It is determined whether or not the diffusion resistance component increase rate Δbx1 estimated based on the current is smaller than the diffusion resistance component increase rate Δby2 calculated based on the current I and the voltage V (step S70).

  If it is determined that Δax1 is larger than Δay1 and Δbx1 is smaller than Δby2 (YES in step S70), ECU 100 determines that the diffusion resistance is increased in the target cell (step S80). . The situation where Δax1 is larger than Δay1 and Δbx1 is smaller than Δby2 corresponds to the region indicated by “abnormal deterioration zone (diffusion resistance increase)” in FIG.

  On the other hand, when it is determined in step S70 that Δax1 is larger than Δay1 and Δbx1 is not smaller than Δby2, that is, Δax1 is smaller than Δay1 and Δbx1 is larger than Δby2 (step S70). In step S90, the ECU 100 determines that the DC resistance is increased in the target cell. The situation where Δax1 is smaller than Δay1 and Δbx1 is larger than Δby2 corresponds to the region indicated by “abnormal deterioration zone (DC resistance increase)” in FIG.

  Then, when the deterioration factor is determined in step S80 or S90, ECU 100 stops using the target cell (step S100).

  As described above, in this embodiment, when the estimation result of the resistance increase based on the temperature information is different from the calculation result of the resistance increase based on the current I and the voltage V, the deterioration abnormality of the lithium ion secondary battery is detected. Since it is determined that it has occurred, it is possible to determine deterioration without limiting the timing of deterioration determination. Further, when it is determined that the deterioration abnormality has occurred, the increase rate Δax1 of the DC resistance component estimated based on the temperature information and the increase rate Δay1 of the DC resistance component calculated based on the current I and the voltage V Of the diffusion resistance component estimated based on the temperature information and the magnitude relationship between the increase ratio Δby2 of the diffusion resistance component calculated based on the current I and the voltage V. It can be determined whether there is a deterioration abnormality accompanying the increase or a deterioration abnormality accompanying an increase in the diffusion resistance component.

  In the above, the monitoring unit 20 corresponds to an example of “detection device” in the present disclosure, and the ECU 100 corresponds to an example of “control device” in the present disclosure. And the monitoring unit 20 and ECU100 comprise the "control system" in this indication.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present disclosure is shown not by the above description of the embodiments but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  1 vehicle, 2 battery system, 10 assembled battery, 20 monitoring unit, 21 voltage sensor, 22 current sensor, 23 temperature sensor, 30 PCU, 41, 42 MG, 50 engine, 60 power split device, 70 drive shaft, 80 drive wheel , 100 ECU, 101 CPU, 102 Memory.

Claims (1)

A control system for a lithium ion secondary battery,
A detection device for detecting the temperature, current and voltage of the lithium ion secondary battery;
A control device,
The controller is
The lithium ion secondary battery is detected from the temperature detected by the detection device using a predetermined relationship between the temperature of the lithium ion secondary battery and the internal resistance increase rate indicating the deterioration rate of the lithium ion secondary battery. Estimate the internal resistance increase rate of
The increase of the DC resistance component from the estimated value of the increase rate of the internal resistance, using a predetermined relationship between the increase rate of the internal resistance and each increase rate of the DC resistance component and diffusion resistance component indicating the component of the internal resistance Estimating a first value indicating a ratio and a second value indicating an increase ratio of the diffusion resistance component;
From the current flowing through the lithium ion secondary battery and the amount of change in voltage, a third value indicating an increase rate of the DC resistance component and a fourth value indicating an increase rate of the diffusion resistance component are calculated.
When the difference between the first value and the third value or the difference between the second value and the fourth value is greater than a predetermined value, the deterioration of the lithium ion secondary battery has occurred. It is determined that
When it is determined that the deterioration abnormality has occurred,
When the first value is larger than the third value and the second value is smaller than the fourth value, there is a deterioration abnormality accompanying an increase in the diffusion resistance component. Judge that
When the first value is smaller than the third value and the second value is larger than the fourth value, there is a deterioration abnormality accompanying an increase in the DC resistance component. A control system for a lithium ion secondary battery, which is determined to be a thing.

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