JP6701938B2 - Deterioration determination device, computer program, and deterioration determination method - Google Patents

Description

  The present invention relates to a deterioration determination device for determining deterioration of a secondary battery, a computer program for realizing the deterioration determination device, and a deterioration determination method.

  In recent years, vehicles such as HEVs (Hybrid Electric Vehicles) and EVs (Electric Vehicles) are becoming popular. HEV and EV are equipped with a secondary battery. The HEV drives the motor by using the electric power stored in the secondary battery to drive the vehicle or assist the engine. Therefore, in the HEV, switching between charging and discharging of the secondary battery is repeated frequently as the vehicle travels. Since over-discharging or over-charging deteriorates the secondary battery, it is necessary to control charging/discharging while grasping the charge amount of the secondary battery. Further, in order to determine the deterioration of the secondary battery, it is necessary to accurately grasp the internal resistance of the secondary battery.

  For example, if it is determined that the magnitude of the charge/discharge current of the secondary battery has continued for a predetermined time or longer in a state of being within a predetermined range, the time elapsed from the detection of switching from charging to discharging or discharging to charging of the secondary battery. There is disclosed an internal resistance estimation device that estimates the internal resistance of a secondary battery based on the above (see Patent Document 1).

JP, 2008-89447, A

  However, the internal resistance value obtained by the internal resistance estimation device disclosed in Patent Document 1 varies depending on the temperature of the secondary battery, SOC (charging rate), and secular change. The deterioration of the secondary battery cannot be determined.

  The present invention has been made in view of the above circumstances, and provides a deterioration determination device capable of determining deterioration of a secondary battery, a computer program for realizing the deterioration determination device, and a deterioration determination method. With the goal.

  A deterioration determination device according to an embodiment of the present invention is a deterioration determination device that determines deterioration of a secondary battery, and acquires a voltage acquisition unit that acquires a voltage of the secondary battery and a current of the secondary battery. A current acquisition unit, a switching determination unit that determines whether charging or discharging of the secondary battery is switched based on the current acquired by the current acquisition unit, and if it is determined that charging or discharging is switched by the switching determination unit, A first resistance calculation unit that calculates the first internal resistance of the secondary battery based on the voltage acquired by the voltage acquisition unit and the current acquired by the current acquisition unit, and the voltage acquired by the voltage acquisition unit and the current A second resistance calculation unit that calculates a second internal resistance of the secondary battery based on the current acquired by the acquisition unit and an equivalent circuit model of the secondary battery; and a first internal resistance calculated by the first resistance calculation unit. And a deterioration determination unit that determines whether or not the secondary battery is deteriorated based on the second internal resistance calculated by the second resistance calculation unit.

  A computer program according to an embodiment of the present invention is a computer program for causing a computer to determine deterioration of a secondary battery, the computer program including: a voltage acquisition unit that acquires a voltage of the secondary battery; A current acquisition unit that acquires the current of the battery, a switching determination unit that determines whether charging or discharging of the secondary battery is switched based on the acquired current, and if it is determined that charging or discharging is switched, the acquired voltage and A first resistance calculator that calculates a first internal resistance of the secondary battery based on a current, and a second internal resistance of the secondary battery based on the acquired voltage and current and an equivalent circuit model of the secondary battery. A second resistance calculation unit that calculates and a deterioration determination unit that determines the presence or absence of deterioration of the secondary battery based on the calculated first internal resistance and second internal resistance.

  A deterioration determination method according to an embodiment of the present invention is a deterioration determination method for determining deterioration of a secondary battery, in which a voltage acquisition unit acquires a voltage of the secondary battery and acquires a current of the secondary battery as a current. Obtained by the unit, the switching determination unit determines the presence/absence of charge/discharge switching of the secondary battery based on the obtained current, and if it is determined that there is charge/discharge switching, based on the obtained voltage and current. The first internal resistance of the secondary battery is calculated by the first resistance calculation unit, and the second internal resistance of the secondary battery is set to the second internal resistance based on the acquired voltage and current and the equivalent circuit model of the secondary battery. The deterioration determination unit determines whether the secondary battery is deteriorated based on the first internal resistance and the second internal resistance calculated by the resistance calculation unit.

  According to the present invention, it is possible to determine the deterioration of the secondary battery.

It is a block diagram showing an example of composition of an important section of a vehicle carrying a battery monitoring device as a deterioration judging device of this embodiment. It is a block diagram which shows an example of a structure of the battery monitoring apparatus as a deterioration determination apparatus of this Embodiment. It is explanatory drawing which shows an example of the impedance spectrum of the secondary battery unit of this Embodiment. It is explanatory drawing which shows an example of the equivalent circuit model of the secondary battery unit of this Embodiment. It is a schematic diagram which shows an example of the relevant information regarding the parameter of the equivalent circuit model of the secondary battery unit of this Embodiment. It is explanatory drawing which shows an example of the internal resistance at the time of the new article of the secondary battery unit of this Embodiment. It is explanatory drawing which shows an example of the internal resistance at the time of the deterioration of the secondary battery unit of this Embodiment. It is explanatory drawing which shows an example of the ratio of the 1st internal resistance with respect to the 2nd internal resistance at the time of a new article of the secondary battery unit of this Embodiment. It is explanatory drawing which shows the 1st example of the ratio of the 1st internal resistance with respect to the 2nd internal resistance at the time of the deterioration of the secondary battery unit of this Embodiment. It is explanatory drawing which shows the 2nd example of the ratio of the 1st internal resistance with respect to the 2nd internal resistance at the time of the deterioration of the secondary battery unit of this Embodiment. It is a flow chart which shows an example of the processing procedure of the battery monitoring device of this embodiment. It is a flow chart which shows an example of the processing procedure of the battery monitoring device of this embodiment. It is a flow chart which shows an example of the internal resistance Rec calculation processing procedure of the battery monitoring device of this embodiment. It is a flow chart which shows an example of an internal resistance Rzx calculation processing procedure of the battery monitoring device of this embodiment.

[Description of Embodiments of the Present Invention]
A deterioration determination device according to an embodiment of the present invention is a deterioration determination device that determines deterioration of a secondary battery, and acquires a voltage acquisition unit that acquires a voltage of the secondary battery and a current of the secondary battery. A current acquisition unit, a switching determination unit that determines whether charging or discharging of the secondary battery is switched based on the current acquired by the current acquisition unit, and if it is determined that charging or discharging is switched by the switching determination unit, A first resistance calculation unit that calculates the first internal resistance of the secondary battery based on the voltage acquired by the voltage acquisition unit and the current acquired by the current acquisition unit, and the voltage acquired by the voltage acquisition unit and the current A second resistance calculation unit that calculates a second internal resistance of the secondary battery based on the current acquired by the acquisition unit and an equivalent circuit model of the secondary battery; and a first internal resistance calculated by the first resistance calculation unit. And a deterioration determination unit that determines whether or not the secondary battery is deteriorated based on the second internal resistance calculated by the second resistance calculation unit.

  A computer program according to an embodiment of the present invention is a computer program for causing a computer to determine deterioration of a secondary battery, the computer program including: a voltage acquisition unit that acquires a voltage of the secondary battery; A current acquisition unit that acquires the current of the battery, a switching determination unit that determines whether charging or discharging of the secondary battery is switched based on the acquired current, and if it is determined that charging or discharging is switched, the acquired voltage and A first resistance calculator that calculates a first internal resistance of the secondary battery based on a current, and a second internal resistance of the secondary battery based on the acquired voltage and current and an equivalent circuit model of the secondary battery. A second resistance calculation unit that calculates and a deterioration determination unit that determines the presence or absence of deterioration of the secondary battery based on the calculated first internal resistance and second internal resistance.

  A deterioration determination method according to an embodiment of the present invention is a deterioration determination method for determining deterioration of a secondary battery, in which a voltage acquisition unit acquires a voltage of the secondary battery and acquires a current of the secondary battery as a current. Obtained by the unit, the switching determination unit determines the presence or absence of charge/discharge switching of the secondary battery based on the obtained current, and if it is determined that there is charge/discharge switching, based on the obtained voltage and current. The first internal resistance of the secondary battery is calculated by the first resistance calculation unit, and the second internal resistance of the secondary battery is set to the second internal resistance based on the acquired voltage and current and the equivalent circuit model of the secondary battery. The deterioration determination unit determines whether the secondary battery is deteriorated based on the first internal resistance and the second internal resistance calculated by the resistance calculation unit.

  The voltage acquisition unit acquires the voltage of the secondary battery, and the current acquisition unit acquires the current (charge current or discharge current) of the secondary battery. The switching determination unit determines whether charging/discharging of the secondary battery is switched based on the current acquired by the current acquisition unit. For example, if one of charge or discharge is defined as positive and the current changes from positive to negative or 0, the current changes from 0 to positive or negative, or the current changes from negative to positive or 0. It can be determined that the charge/discharge has been switched.

  The first resistance calculation unit calculates the first internal resistance of the secondary battery based on the acquired voltage and current when the switching determination unit determines that charging/discharging is switched. When switching from charging to discharging or from discharging to charging, of the internal resistance of the secondary battery (including, for example, the resistance of the electrolyte bulk, the charge transfer resistance, and the diffusion resistance), for example, the diffusion resistance and the charge transfer resistance are Will be reset. Therefore, when it is determined that charging/discharging is switched, the first internal resistance of the secondary battery can be calculated by acquiring the voltage Vc and the current Ic. The first internal resistance is also represented as Rzx.

  The second resistance calculation unit calculates the second internal resistance of the secondary battery based on the acquired voltage and current and the equivalent circuit model of the secondary battery. The equivalent circuit model is an equivalent circuit that represents the impedance of the secondary battery, and can be represented by, for example, an impedance configured by a combination of a voltage source having an open circuit voltage OCV, a resistor, and a parallel circuit of a resistor and a capacitor. The second internal resistance is calculated, for example, by obtaining a voltage (also referred to as an overvoltage) in the equivalent circuit model based on the equivalent circuit model of the secondary battery and the current of the secondary battery, and calculating the loss component excluding the reactance component of the overvoltage. It can be calculated based on the current. The second internal resistance is also represented as Rec.

  The deterioration determination unit determines whether the secondary battery is deteriorated based on the calculated first internal resistance and second internal resistance. The second internal resistance changes according to the temperature of the secondary battery and SOC (State Of Charge). On the other hand, the first internal resistance changes according to deterioration of the secondary battery, temperature, and SOC. Therefore, if the temperature change and the SOC change of the secondary battery are offset based on the calculated first internal resistance and second internal resistance, it is possible to determine the deterioration of the secondary battery.

  A deterioration determination device according to an embodiment of the present invention includes a ratio calculation unit that calculates a ratio of the first internal resistance to the second internal resistance, and the deterioration determination unit is configured to calculate the ratio calculated by the ratio calculation unit. Whether the secondary battery has deteriorated is determined based on the size.

  The ratio calculator calculates the ratio of the first internal resistance to the second internal resistance. For example, when the first internal resistance is Rzx and the second internal resistance is Rec, the ratio can be represented by Rzx/Rec.

  The deterioration determination unit determines whether or not the secondary battery has deteriorated based on the magnitude of the ratio calculated by the ratio calculation unit. When the secondary battery is new, the first internal resistance Rzx and the second internal resistance Rec have approximately the same value, and the ratio is 1 or a value in the vicinity of 1. On the other hand, when the secondary battery deteriorates, the second internal resistance Rec tends to hardly change, while the first internal resistance Rzx tends to gradually increase. Therefore, it can be seen that the deterioration of the secondary battery progresses as the ratio increases.

  The deterioration determination device according to the embodiment of the present invention is configured such that the deterioration determination unit determines whether the ratio calculated by the ratio calculation unit is equal to or greater than a threshold value of one of a plurality of different threshold values. The deterioration state of the battery is judged in multiple stages.

  The deterioration determination unit determines the deterioration state of the secondary battery in a plurality of stages depending on whether or not the ratio calculated by the ratio calculation unit is equal to or more than one of a plurality of different thresholds. For example, thresholds Th1 and Th2 (>Th1) are provided. When the calculated ratio is greater than or equal to the threshold Th2, it is determined that the secondary battery is in an abnormal state. If the ratio is greater than or equal to the threshold value Th1 and less than the threshold value Th2, it is determined that the warning state does not lead to an abnormal state, but may be an abnormal state in the future. With the above-described configuration, the deterioration state can be classified and determined in more detail than the level indicating whether or not the secondary battery is simply normal.

  In the deterioration determination device according to the embodiment of the present invention, the ratio calculation unit calculates a repetition ratio, and the deterioration determination unit determines the number of times the ratio calculated by the ratio calculation unit is equal to or more than the threshold value. Is a predetermined number of times or more, it is determined that the secondary battery is in a deterioration state corresponding to the threshold value.

  The ratio calculation unit calculates the repetition ratio. The deterioration determination unit determines that the secondary battery is in a deterioration state corresponding to the threshold when the number of times the ratio calculated by the ratio calculation unit is equal to or larger than any threshold is a predetermined number or more. The predetermined number of times can be set to 10, for example, but is not limited to this.

  When the deterioration state of the secondary battery progresses, the change in the ratio is relatively gradual. That is, when the number of times the ratio is equal to or greater than the threshold is small, it is not possible to accurately determine the deterioration of the secondary battery. Therefore, when the number of times the ratio is equal to or greater than the threshold is equal to or greater than the predetermined number, it is possible to accurately determine the deterioration state of the secondary battery by determining that the deterioration state corresponds to the threshold.

  A deterioration determination device according to an embodiment of the present invention includes an overvoltage calculation unit that calculates an overvoltage of the secondary battery based on a parameter of the equivalent circuit model and a current acquired by the current acquisition unit, and the second resistance. The calculator calculates the second internal resistance of the secondary battery based on the overvoltage calculated by the overvoltage calculator and the current acquired by the current acquirer.

  The overvoltage calculation unit calculates the overvoltage of the secondary battery based on the parameters (resistance, capacitor and OCV) of the equivalent circuit model and the acquired current. Overvoltage is the difference between the terminal voltage and OCV, and OCV represents the static state of the terminal voltage of the secondary battery, while overvoltage represents the dynamic state of the terminal voltage of the secondary battery. The overvoltage can be calculated based on the impedance and current of the secondary battery represented by the equivalent circuit model.

  The second resistance calculation unit calculates the second internal resistance of the secondary battery based on the overvoltage calculated by the overvoltage calculation unit and the acquired current. The second internal resistance is a resistance component of the impedance of the secondary battery. For example, when the overvoltage is Ve and the current is Ic, the second internal resistance Rec can be calculated by the formula Rec=Ve/Ic. Thereby, the internal resistance that is not affected by the deterioration of the secondary battery can be calculated.

  A deterioration determination device according to an embodiment of the present invention includes a storage unit that stores related information that associates each of the temperature and the charging rate of the secondary battery with the parameter, and a temperature acquisition unit that acquires the temperature of the secondary battery. Section, a charging rate calculating section for calculating the charging rate of the secondary battery, a temperature acquired by the temperature acquiring section, a charging rate calculated by the charging rate calculating section, and related information stored in the storage section. The overvoltage calculation unit calculates the overvoltage of the secondary battery based on the parameter corrected by the correction unit.

  The storage unit stores the related information in which the temperature and the charging rate of the secondary battery are associated with the parameters of the equivalent circuit model. As the related information, for example, information indicating the relationship between each parameter and SOC at a certain temperature can be associated with a plurality of different temperatures.

  The temperature acquisition unit acquires the temperature of the secondary battery. The charging rate calculation unit calculates the charging rate of the secondary battery. The charging rate can be calculated, for example, by integrating the currents acquired by the current acquisition unit. That is, when the most recently obtained charging rate is SOCin, the charging rate SOC can be calculated by the equation SOC=SOCin±{ΣIbi×Δt (i=1, 2,... )/Full charge capacity FCC}. Here, Ibi is the current value acquired at each sampling, and Δt is the sampling interval. The symbol ± indicates whether charging or discharging is performed.

  The correction unit corrects the parameter based on the acquired temperature, the charging rate calculated by the charging rate calculation unit, and the related information stored in the storage unit. The overvoltage calculation unit calculates the overvoltage of the secondary battery based on the parameters corrected by the correction unit. As a result, the effect of temporary deterioration due to temperature and charge rate can be excluded, it can be used as a reference value for internal resistance that is not affected by the deterioration state, and a permanent deterioration state can be determined. You can

  The deterioration determination device according to the embodiment of the present invention, when the switching determination unit determines that there is charge/discharge switching, initialization for initializing a calculation state in the equivalent circuit model that occurs when the overvoltage is calculated. Section.

  When the switching determination unit determines that charging/discharging is switched, the initialization unit initializes a calculation state in the equivalent circuit model generated when the overvoltage is calculated. In the process of calculating the overvoltage, a voltage is generated by the current in each parameter in the equivalent circuit model. For example, electric charge is accumulated in the capacitor in the equivalent circuit model due to the current. Then, every time the overvoltage is calculated, the electric charge due to the current is accumulated in the capacitor and remains as a charge/discharge history. Initializing the operation state means making the charge of the capacitor zero.

  Also in the case of calculating the first internal resistance Rzx, for example, the diffusion resistance and the charge transfer resistance are once reset on condition that the charge/discharge is switched. Also in the case of calculating the second internal resistance Rec, the calculation state in the equivalent circuit model is initialized under the condition that charging/discharging is switched to match (or approach) the calculation condition of the first internal resistance Rzx. Since it is possible to obtain the ratio with high accuracy, it is possible to accurately determine the deterioration state.

  Deterioration determination device according to an embodiment of the present invention, in the impedance spectrum of the secondary battery, based on the boundary frequency range in which the diffusion impedance due to the diffusion process of predetermined ions contributes to the impedance of the secondary battery. When the switching determination unit determines that there is charge/discharge switching, the first resistance calculation unit includes a specifying unit that specifies a standby time, and the voltage acquired by the voltage acquisition unit after the standby time specified by the specifying unit. And a first internal resistance of the secondary battery based on the current acquired by the current acquisition unit.

  The specifying unit specifies the standby time in the impedance spectrum of the secondary battery based on the boundary frequency range in which the diffusion impedance resulting from the diffusion process of a predetermined ion contributes to the impedance of the secondary battery. The impedance spectrum is also referred to as a Cole-Cole plot or a Nyquist plot, and is a plot of values obtained by measuring the impedance of the secondary battery at a plurality of frequencies using the AC impedance method.

  The internal resistance of the secondary battery is dominated by the resistance Rs of the electrolyte bulk and the interface charge transfer resistance Rc. On the other hand, when the frequency in the AC impedance method is changed from a high frequency to a low frequency, the diffusion impedance Zw increases and the internal resistance of the secondary battery also increases in a certain frequency range (referred to as a boundary frequency range) (two. Contributes to the impedance of the secondary battery). Therefore, the internal resistance (first internal resistance described later) of the secondary battery is obtained at the timing before the diffusion impedance Zw increases. The relationship of T=1/(2×f), that is, the waiting time T is, for example, the frequency f in the frequency impedance f It can be specified from the relationship of the reciprocal of twice. For example, when the frequency f is 5 Hz, the waiting time T is 0.1 seconds. Note that the waiting time T is set to the reciprocal of twice the frequency f, which is just an example.

  When the switching determination unit determines that charging/discharging is switched, the first resistance calculation unit recharges the secondary battery based on the voltage acquired by the voltage acquisition unit and the current acquired by the current acquisition unit after the standby time specified by the specification unit. The first internal resistance of is calculated. When the charging is switched to the discharging or the discharging is switched to the charging, among the internal resistances of the secondary battery, for example, the diffusion resistance (diffusion impedance) and the charge transfer resistance are once reset, and the internal resistance starts to increase according to the energization time. Therefore, when it is determined that charging/discharging is switched, the first internal resistance of the secondary battery can be calculated by acquiring the voltage Vc and the current Ic after the waiting time T. With this, the first internal resistance can be obtained in a short time (for example, about 0.1 seconds) after switching between charging and discharging, and thus even when charging and discharging are frequently repeated, it is relatively short after switching between charging and discharging. The first internal resistance of the secondary battery can be calculated accurately with time.

[Details of Embodiment of Present Invention]
Hereinafter, an embodiment of a deterioration determination device according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a configuration of a main part of a vehicle equipped with a battery monitoring device 100 as a deterioration determining device of the present embodiment. As shown in FIG. 1, in addition to the battery monitoring device 100, the vehicle includes a secondary battery unit 50, relays 61 and 63, a generator (ALT) 62, a starter motor (ST) 64, a battery 65, an electric load 66, and the like. Equipped with.

  The secondary battery unit 50 is, for example, a lithium ion battery, and a plurality of cells 51 are connected in series or series/parallel. The secondary battery unit 50 includes a voltage sensor 52, a current sensor 53, and a temperature sensor 54. The voltage sensor 52 detects the voltage of each cell 51 and the terminal voltage of the secondary battery unit 50, and outputs the detected voltage via the voltage detection line 50a to the battery monitoring device 100. The current sensor 53 is composed of, for example, a shunt resistor or a Hall sensor, and detects the charging current and the discharging current of the secondary battery. The current sensor 53 outputs the current detected through the current detection line 50b to the battery monitoring device 100. The temperature sensor 54 is composed of, for example, a thermistor, and detects the temperature of the cell 51. The temperature sensor 54 outputs the temperature detected via the temperature detection line 50c to the battery monitoring device 100.

  The battery 65 is, for example, a lead battery and supplies electric power to the electric load 66 of the vehicle and also supplies electric power to drive the starter motor 64 when the relay 63 is turned on. The generator 62 generates electric power by rotation of the engine of the vehicle and outputs DC by a rectifying circuit provided inside to charge the battery 65. Further, the generator 62 charges the battery 65 and the secondary battery unit 50 when the relay 61 is on. The relays 61 and 63 are turned on/off by a relay controller (not shown).

  FIG. 2 is a block diagram showing an example of the configuration of the battery monitoring device 100 as the deterioration determination device of the present embodiment. The battery monitoring device 100 includes a control unit 10 that controls the entire device, a voltage acquisition unit 11, a current acquisition unit 12, a temperature acquisition unit 13, a switching determination unit 14, a standby time identification unit 15, a first resistance calculation unit 16, and a second resistance calculation unit 16. A resistance calculation unit 17, a deterioration determination unit 18, a ratio calculation unit 19, an overvoltage calculation unit 20, a charging rate calculation unit 21, a correction unit 22, a storage unit 23, a timer 24 for clocking, and the like are provided.

  The voltage acquisition unit 11 acquires the voltage of the secondary battery unit 50 (the voltage of each cell 51 and the terminal voltage of the secondary battery unit 50). The current acquisition unit 12 also acquires the current (charge current and discharge current) of the secondary battery unit 50. The control unit 10 can control the acquisition frequency of the voltage and the current and the sampling period to be acquired.

  The switching determination unit 14 determines whether charging/discharging of the secondary battery unit 50 is switched based on the current acquired by the current acquisition unit 12. For example, if the current acquired by the current acquisition unit 12 in the case of charging is set to be positive, the directions of the currents are opposite between charging and discharging, so if the current acquired by the current acquisition unit 12 is negative, It can be determined that the discharge. That is, one of charge or discharge is defined as positive, and when the current changes from positive to negative or 0, when the current changes from 0 to positive or negative, or when the current changes from negative to positive or 0. It can be determined that the charge/discharge has been switched.

  The standby time specifying unit 15 has a function as a specifying unit, and in the impedance spectrum of the secondary battery unit 50, the boundary where the diffusion impedance due to the diffusion process of a predetermined ion contributes to the impedance of the secondary battery unit 50. The waiting time is specified based on the frequency range. The impedance spectrum is also called a Cole-Cole plot or a Nyquist plot, and is a plot of values obtained by measuring the impedance of the secondary battery unit 50 at a plurality of frequencies using the AC impedance method. Further, the predetermined ions are lithium (Li) ions. The boundary frequency range means that the frequency has a required width, and is not limited to one frequency.

  FIG. 3 is an explanatory diagram showing an example of the impedance spectrum of the secondary battery unit 50 of the present embodiment. In FIG. 3, the horizontal axis represents the real number component Zr of the impedance Z, and the vertical axis represents the imaginary number component Zi of the impedance Z. The internal resistance of the secondary battery unit 50 is dominated by the resistance Rs of the electrolyte bulk and the interface charge transfer resistance Rc. On the other hand, when the frequency in the AC impedance method is changed from a high frequency to a low frequency (for example, 100 kHz to 0.01 mHz or 1 MHz to 10 μHz), as shown in FIG. Name: near the area indicated by symbol A in FIG. 3), the diffusion impedance Zw increases and the impedance of the secondary battery unit 50 increases (contributes to the impedance of the secondary battery).

  That is, in the impedance spectrum of the secondary battery unit 50, the fact that the diffusion impedance resulting from the diffusion process of a predetermined ion contributes to the impedance of the secondary battery unit 50 means that the frequency (or angular frequency) changes from high frequency to low frequency. When it decreases toward the bottom, it means that the diffusion impedance Zw increases and the impedance of the secondary battery unit 50 increases. That is, in the boundary frequency region, the impedance of the secondary battery unit 50 can be represented by the total value of the resistance Rs of the electrolyte bulk and the interface charge transfer resistance Rc, and the influence (contribution) by the diffusion impedance Zw is small or neglected. It means the frequency range in which it can be performed. The AC impedance method applies an AC voltage having a changed frequency to the secondary battery unit 50, and converts the current signal and the voltage signal obtained from the secondary battery unit 50 into the frequency domain by discrete Fourier transform, It is to obtain the impedance.

In FIG. 3, when w=∞, the impedance Z at the point where the locus intersects the horizontal axis is Z=Zr=Rs. Further, the impedance Z at the center of the semicircular locus (the point intersecting the horizontal axis) is Z=Zr=Rs+Rc/2. Further, in FIG. 3, it can be seen that the locus of the impedance Z increases linearly when w becomes smaller than the boundary frequency band indicated by the symbol A. The impedance Z at the point where the extension line obtained by extending the straight line intersects the horizontal axis is Z=Zr=Rs+R−2σ ² C. A frequency region smaller than the boundary frequency region indicated by reference symbol A is a region due to the diffusion process of lithium ions, and the diffusion impedance Zw increases as the frequency decreases.

  As for the internal resistance of the secondary battery unit 50, the resistance Rs of the electrolyte bulk and the interface charge transfer resistance Rc occupy the main part. On the other hand, when the frequency in the AC impedance method is changed from the high frequency to the low frequency, the diffusion impedance Zw increases and the internal resistance of the secondary battery unit 50 also increases in a certain frequency range (referred to as boundary frequency range). (Contributes to the impedance of the secondary battery unit 50). Therefore, the internal resistance (first internal resistance Rzx described later) of the secondary battery unit 50 is calculated at a timing before the diffusion impedance Zw increases.

  The relationship of T=1/(2×f), that is, the waiting time T is, for example, the frequency f in the frequency impedance f It can be specified from the relationship of the reciprocal of twice. For example, when the frequency f is 5 Hz, the waiting time T is 0.1 seconds. Note that the waiting time T is set to the reciprocal of twice the frequency f, which is just an example. For example, the waiting time T may be set to the reciprocal of four times the frequency f.

  When the switching determination unit 14 determines that charging/discharging is switched, the first resistance calculation unit 16 calculates the first internal resistance of the secondary battery unit 50 based on the acquired voltage and current. When switching from charging to discharging or from discharging to charging, of the internal resistances of the secondary battery unit 50 (including, for example, the resistance of the bulk of the electrolytic solution, the charge transfer resistance, and the diffusion resistance), for example, the diffusion resistance and the charge transfer resistance are included. Is reset once. Therefore, when it is determined that charging/discharging is switched, the first internal resistance of the secondary battery unit 50 can be calculated by acquiring the voltage Vc and the current Ic. The first internal resistance is also represented as Rzx.

  In addition, when the switching determination unit 14 determines that charging/discharging is switched, the first resistance calculation unit 16 acquires the voltage and current acquisition unit 12 acquired by the voltage acquisition unit 11 after the standby time T specified by the standby time specification unit 15. The first internal resistance Rzx of the secondary battery unit 50 is calculated on the basis of the current acquired in.

  When switching from charging to discharging or from discharging to charging, the internal resistance of the secondary battery unit 50 starts to increase according to the energization time. Therefore, when it is determined that charging/discharging is switched, the first internal resistance of the secondary battery unit 50 can be calculated by acquiring the voltage Vc and the current Ic after the waiting time T. With this, the first internal resistance can be obtained in a short time (for example, about 0.1 seconds) after switching between charging and discharging, and thus even when charging and discharging are frequently repeated, it is relatively short after switching between charging and discharging. The first internal resistance Rzx of the secondary battery can be calculated accurately with time.

  More specifically, the first resistance calculation unit 16 determines the voltage Vb acquired by the voltage acquisition unit 11 and the current Ib acquired by the current acquisition unit 12 before the switching determination unit 14 determines that charging/discharging is switched, and The first internal resistance Rzx of the secondary battery unit 50 is calculated based on the voltage Vc acquired by the voltage acquisition unit 11 and the current Ic acquired by the current acquisition unit 12 after the standby time T specified by the standby time specifying unit 15.

  The absolute value of the slope of the straight line obtained from the voltage and the current between the two points indicates the first internal resistance Rzx of the secondary battery unit 50. Therefore, the first internal resistance Rzx can be calculated by Rzx=(Vc-Vb)/(Ic-Ib).

  In addition, the first resistance calculation unit 16 sets the first internal resistance Rzx of the secondary battery unit 50 when the current acquired by the current acquisition unit 12 after the standby time T specified by the standby time specifying unit 15 is larger than a predetermined threshold value. It can also be calculated.

  When the current obtained after the waiting time T has elapsed is small, the first internal resistance Rzx cannot be calculated accurately, so by adding the condition that the current is larger than a predetermined threshold value, the first internal resistance Rzx is added. The calculation accuracy of Rzx can be improved.

  The second resistance calculation unit 17 calculates the second internal resistance of the secondary battery unit 50 based on the acquired voltage and current and the equivalent circuit model of the secondary battery unit 50. The second internal resistance is also represented as Rec.

  FIG. 4 is an explanatory diagram showing an example of an equivalent circuit model of the secondary battery unit 50 of the present embodiment. The equivalent circuit model (also referred to as a battery equivalent circuit model) is an equivalent circuit representing the impedance of the secondary battery unit 50. For example, as shown in FIG. 4, a voltage source having an open circuit voltage OCV, a resistor R1, a resistor and a capacitor. And a parallel circuit (in FIG. 4, four parallel circuits of resistors R2 to R5 and capacitors C2 to C5 are connected in series), and the like. The secondary battery unit 50 is determined by a voltage source having an open circuit voltage OCV, a series resistance of internal impedance, and the like. The open circuit voltage OCV is determined by the static balance of the positive electrode, the negative electrode and the electrolyte, and the internal impedance is determined by a dynamic mechanism.

  More specifically, the resistor R1 represents, for example, the resistance of the electrolytic solution bulk, the resistors R2 to R5 represent, for example, the interface charge transfer resistance and the diffusion impedance, and the capacitors C2 to C5 represent, for example, the electric double layer capacitance. Represents. The resistance of the electrolyte bulk includes the conduction resistance of lithium (Li) ions in the electrolyte, the electronic resistance of the positive electrode and the negative electrode, and the like. The interface charge transfer resistance includes a charge transfer resistance and a film resistance on the surface of the active material. The diffusion impedance is an impedance caused by a diffusion process of lithium (Li) ions inside the active material particles. The equivalent circuit model of the secondary battery unit 50 is an example, and is not limited to the example of FIG.

  The second internal resistance Rec is calculated, for example, by obtaining a voltage (also referred to as an overvoltage) in the equivalent circuit model based on the equivalent circuit model of the secondary battery unit 50 and the current Ib of the secondary battery unit 50, and determining the reactance component of the overvoltage. It can be calculated based on the loss component and the current except for.

  That is, the overvoltage calculation unit 20 calculates the overvoltage of the secondary battery unit 50 based on the parameters (resistance, capacitor and OCV) of the equivalent circuit model and the acquired current. As shown in FIG. 4, the overvoltage is the difference between the voltage Vb (terminal voltage) and the OCV, and while OCV represents the static state of the terminal voltage of the secondary battery unit 50, the overvoltage is the secondary battery. 5 represents the dynamic state of the terminal voltage of unit 50. The overvoltage can be calculated based on the impedance of the secondary battery unit 50 and the current Ib represented by an equivalent circuit model.

  The second resistance calculation unit 17 calculates the second internal resistance Rec of the secondary battery unit 50 based on the overvoltage calculated by the overvoltage calculation unit 20 and the acquired current. The second internal resistance Rec is a resistance component of the impedance of the secondary battery unit 50. For example, when the overvoltage is Ve and the current is Ic, the second internal resistance Rec can be calculated by the formula Rec=Ve/Ic. As a result, the internal resistance that is not affected by the deterioration of the secondary battery unit 50 can be calculated.

  The deterioration determination unit 18 determines whether or not the secondary battery unit 50 is deteriorated based on the calculated first internal resistance and second internal resistance. The second internal resistance changes according to the temperature of the secondary battery unit 50 and SOC (State Of Charge). On the other hand, the first internal resistance changes according to deterioration of the secondary battery unit 50, temperature, and SOC. Therefore, if the temperature change and the SOC change of the secondary battery unit 50 are offset based on the calculated first internal resistance and second internal resistance, the deterioration of the secondary battery unit 50 can be determined.

  The storage unit 23 stores the related information in which the temperature and the charging rate of the secondary battery unit 50 are associated with the parameters of the equivalent circuit model. As the related information, for example, information indicating the relationship between each parameter and SOC at a certain temperature can be defined for each of a plurality of different temperatures.

  FIG. 5 is a schematic diagram showing an example of related information regarding parameters of the equivalent circuit model of the secondary battery unit 50 of the present embodiment. The related information is, for example, that each parameter (for example, R1, R2, C2, R3, C3, R4, C4, R5, C5) of the equivalent circuit model illustrated in FIG. A correction table that indicates what value will be obtained according to the change is set for each temperature (..., 25° C.,..., 40° C.,... ).

  The temperature acquisition unit 13 acquires the temperature of the secondary battery unit 50.

  The charging rate calculator 21 calculates the charging rate of the secondary battery unit 50. The charging rate can be calculated by integrating the currents acquired by the current acquisition unit 12, for example. That is, assuming that the most recently obtained charging rate is SOCin, the charging rate SOC can be calculated by the formula SOC=SOCin±{ΣIbi×Δt (i=1, 2,... )/Full charge capacity FCC}. Here, Ibi is the current value acquired at each sampling, and Δt is the sampling interval. The symbol ± indicates whether charging or discharging is performed.

  The correction unit 22 corrects the parameters of the equivalent circuit model of the secondary battery unit 50 based on the acquired temperature, the charging rate calculated by the charging rate calculation unit 21, and the related information (correction table) stored in the storage unit 23.

  The overvoltage calculation unit 20 calculates the overvoltage of the secondary battery unit 50 based on the parameters corrected by the correction unit 22. As a result, it is possible to exclude the influence of temporary deterioration due to temperature and charging rate, use the second internal resistance Rec as a reference value that is not affected by the deterioration state, and determine the permanent deterioration state. It can be performed.

  The control unit 10 has a function as an initialization unit, and when the switching determination unit 14 determines that charging/discharging is switched, the control unit 10 initializes a calculation state in the equivalent circuit model generated when the overvoltage is calculated. In the process of calculating the overvoltage, a voltage is generated by the current in each parameter in the equivalent circuit model. For example, electric charge is accumulated in the capacitor in the equivalent circuit model due to the current. Then, every time the overvoltage is calculated, the electric charge due to the current is accumulated in the capacitor and remains as a charge/discharge history. Initializing the operation state means making the charge of the capacitor zero.

  Also in the case of calculating the first internal resistance Rzx, for example, the diffusion resistance and the charge transfer resistance are once reset on condition that the charge/discharge is switched. Also in the case of calculating the second internal resistance Rec, the calculation state in the equivalent circuit model is initialized under the condition that charging/discharging is switched to match (or approach) the calculation condition of the first internal resistance Rzx. Therefore, when determining the deterioration of the secondary battery unit 50 based on the first internal resistance and the second internal resistance, the deterioration state can be accurately determined.

  Next, the deterioration determination of the secondary battery unit 50 will be described in detail. FIG. 6 is an explanatory diagram showing an example of the internal resistance of the secondary battery unit 50 of the present embodiment when it is new. In FIG. 6, the calculation point number is calculated by the first internal resistance Rzx (also simply referred to as internal resistance Rzx) calculated by the first resistance calculation unit 16 and the second resistance calculation unit 17, starting from the charge/discharge switching time point. The second internal resistance Rec (also simply referred to as the internal resistance Rec) is plotted. As shown in FIG. 6, when the secondary battery unit 50 is new and is not deteriorated, the difference between the first internal resistance Rzx and the second internal resistance Rec is small.

  FIG. 7 is an explanatory diagram showing an example of internal resistance when the secondary battery unit 50 of the present embodiment is deteriorated. In FIG. 7, the calculation point number is a plot of values calculated in the same manner as in FIG. As shown in FIG. 7, in the state where the secondary battery unit 50 is deteriorated, the second internal resistance Rec does not change much compared to the case of a new product, while the first internal resistance Rzx is new. It can be seen that the resistance value becomes larger than that in the case of time.

  The ratio calculator 19 calculates the ratio of the first internal resistance to the second internal resistance. For example, when the first internal resistance is Rzx and the second internal resistance is Rec, the ratio can be represented by Rzx/Rec.

  The deterioration determination unit 18 determines whether the secondary battery unit 50 is deteriorated based on the magnitude of the ratio calculated by the ratio calculation unit 19.

  FIG. 8 is an explanatory diagram showing an example of the ratio of the first internal resistance to the second internal resistance when the secondary battery unit 50 of the present embodiment is new. As shown in FIG. 8, when the secondary battery unit 50 is a new product, the first internal resistance Rzx and the second internal resistance Rec have approximately the same value, and the ratio is 1 or a value in the vicinity of 1. In FIG. 8, the first threshold Th1 is a threshold for determining whether or not the deterioration of the secondary battery unit 50 is in a warning state, and the second threshold Th2 is a warning state of the deterioration of the secondary battery unit 50. It is a threshold value for determining whether or not the condition is more severe.

  On the other hand, when the secondary battery unit 50 deteriorates, as shown in FIG. 7, the second internal resistance Rec has a tendency to hardly change, whereas the first internal resistance Rzx tends to gradually increase. Therefore, it can be seen that the deterioration of the secondary battery unit 50 progresses as the ratio calculated by the ratio calculator 19 increases.

  Further, the deterioration determination unit 18 determines the deterioration state of the secondary battery unit 50 in a plurality of stages depending on whether or not the ratio calculated by the ratio calculation unit 19 is equal to or higher than one of a plurality of different thresholds. be able to.

  For example, a first threshold Th1 and a second threshold Th2 (>Th1) for the ratio are set. The first threshold Th1 can be set to 2, for example, and the second threshold Th2 can be set to 3, for example. The numerical values are not limited to these. When the calculated ratio is greater than or equal to the second threshold Th2, it is determined that the secondary battery unit 50 is in an abnormal state. Further, when the ratio is equal to or more than the first threshold Th1 and less than the second threshold Th2, it is determined that the warning state does not lead to the abnormal state, but may become the abnormal state in the future. With the above configuration, the deterioration state can be classified and determined in more detail than the level of whether the secondary battery unit 50 is simply normal or not.

  Further, the ratio calculation unit 19 calculates the repetition ratio.

  The deterioration determination unit 18 includes a counter, and when the number of times the ratio calculated by the ratio calculation unit 19 is equal to or greater than any threshold is equal to or greater than a predetermined number, the secondary battery unit 50 is in a degraded state corresponding to the threshold. Judge that there is. The predetermined number of times can be set to 10, for example, but is not limited to this.

  FIG. 9 is an explanatory diagram showing a first example of the ratio of the first internal resistance to the second internal resistance when the secondary battery unit 50 of the present embodiment is deteriorated. As shown in FIG. 9, at the calculation point number 2, the ratio becomes equal to or higher than the first threshold Th1, and thereafter, at the calculation point numbers 3 to 13, the ratio continuously becomes equal to or higher than the first threshold Th1. In the calculation point number 10, the ratio is equal to or higher than the second threshold Th2. Assuming that the predetermined number of times is 10, for example, as shown in FIG. 9, in the calculation point number 11, the number of times when the ratio continuously becomes the first threshold Th1 or more becomes the predetermined number or more. Therefore, it is determined that the calculated point number 11 is in the warning state.

  FIG. 10 is an explanatory diagram showing a second example of the ratio of the first internal resistance to the second internal resistance when the secondary battery unit 50 of the present embodiment is deteriorated. As shown in FIG. 10, at the calculation point number 3, the ratio becomes the second threshold value Th2 or more, and thereafter, at the calculation point numbers 4 to 13, the ratio continuously becomes the second threshold value Th2 or more. Assuming that the predetermined number of times is 10, for example, as shown in FIG. 10, in the calculation point number 12, the number of times when the ratio continuously becomes the second threshold value Th2 or more becomes the predetermined number of times or more. Therefore, in the calculation point number 12, it is determined that the abnormal state is severer than the warning state.

  When the deterioration state of the secondary battery unit 50 progresses, the change in the ratio is relatively gradual. That is, when the number of times the ratio is equal to or greater than the threshold is small, it is not possible to accurately determine the deterioration of the secondary battery unit 50. Therefore, when the number of times the ratio is equal to or greater than the threshold is equal to or greater than the predetermined number, it is possible to accurately determine the deterioration state of the secondary battery unit 50 by determining that the deterioration state corresponds to the threshold. In the above example, the configuration in which two thresholds are provided and the deterioration state is determined in two stages has been described, but the number of thresholds is not limited to two. For example, the deterioration state of the secondary battery unit 50 can be determined in more stages by providing three or more threshold values.

  Next, the operation of the battery monitoring device 100 of this embodiment will be described. 11 and 12 are flowcharts showing an example of the processing procedure of the battery monitoring device 100 of the present embodiment. Hereinafter, for the sake of convenience, the main body of processing will be described as the control unit 10. The control unit 10 sets the counters C1 and C2 to 0 (S11). The counter C1 is a counter for determining a warning state, and the counter C2 is for determining an abnormal state.

  The control unit 10 calculates the internal resistance Rec (S12) and calculates the internal resistance Rzx (S13). The details of the calculation process of the internal resistance Rec and the calculation process of the internal resistance Rzx will be described later. The control unit 10 determines whether it is a comparison timing (S14). The comparison timing can be, for example, the timing at which the standby time T has elapsed after switching between charging and discharging.

  If it is not the comparison timing (NO in S14), the control unit 10 continues the processing from step S12. When it is the comparison timing (YES in S14), the control unit 10 calculates the ratio of the internal resistance Rzx to the internal resistance Rec, and determines whether the calculated ratio is the second threshold Th2 or more (S15).

  When the ratio is equal to or greater than the second threshold Th2 (YES in S15), the control unit 10 increments the counter C2 by 1 (S16). When the ratio is not equal to or more than the second threshold Th2 (NO in S15), the control unit 10 sets the counter C2 to 0 and clears it (S17).

  The control unit 10 determines whether the calculated ratio is equal to or more than the first threshold Th1 (S18). When the ratio is equal to or higher than the first threshold Th1 (YES in S18), the control unit 10 increments the counter C1 by 1 (S19). When the ratio is not equal to or higher than the first threshold Th1 (NO in S18), the control unit 10 clears the counter C1 to 0 (S20).

  The control unit 10 determines whether or not the counter C2 is a predetermined number N2 (for example, 10) or more (S21). When the counter C2 is equal to or greater than the predetermined number N2 (YES in S21), the control unit 10 determines that the deterioration of the secondary battery unit 50 is in an abnormal state (S22), and performs the process of step S25 described below.

  When the counter C2 is not the predetermined number N2 or more (NO in S21), the control unit 10 determines whether the counter C1 is the predetermined number N1 (for example, 10) or more (S23). When the counter C1 is equal to or greater than the predetermined number N1 (YES in S23), the control unit 10 determines that the deterioration of the secondary battery unit 50 is in the warning state (S24), and performs the process of step S25 described below.

  When the counter C1 is not equal to or more than the predetermined number N1 (NO in S23), the control unit 10 determines whether or not to end the process (S25), and when the process is not to be ended (NO in S25), the processes in and after step S12. Continue. When ending the process (YES in S25), the control unit 10 ends the process.

  FIG. 13 is a flowchart showing an example of the internal resistance Rec calculation processing procedure of the battery monitoring device 100 of the present embodiment. The control unit 10 acquires the voltage of the secondary battery unit 50 (S101) and acquires the current of the secondary battery unit 50 (S102). The control unit 10 determines whether charging/discharging is switched based on the acquired current (S103).

  When it is determined that the charging/discharging is switched (YES in S103), the control unit 10 resets the calculation state in the equivalent circuit model of the secondary battery unit 50 (S104), and the temperature and charge of the secondary battery unit 50. The parameters of the equivalent circuit model are corrected based on the rate (S105). When determining that there is no charge/discharge switching (NO in S103), the control unit 10 performs the process of step S105 without performing the process of step S104.

  The control unit 10 calculates the overvoltage of the secondary battery unit 50 based on the equivalent circuit model and the current (S106), calculates the internal resistance Rec based on the calculated overvoltage (S107), and ends the process.

  FIG. 14 is a flowchart showing an example of an internal resistance Rzx calculation processing procedure of the battery monitoring device 100 of the present embodiment. The control unit 10 acquires the voltage of the secondary battery unit 50 (S121) and acquires the current of the secondary battery unit 50 (S122). The control unit 10 determines whether or not charging/discharging is switched based on the acquired current (S123).

  When there is no charge/discharge switching (NO in S123), the control unit 10 continues the processing from step S121. When the charge/discharge is switched (YES in S123), the control unit 10 stores the voltage Vb and the current Ib acquired immediately before the charge/discharge switching in the storage unit 22 (S124).

  The control unit 10 determines whether or not the standby time has elapsed (S125), and when the standby time has not elapsed (NO in S125), continues the processing from step S125.

  When the standby time has elapsed (YES in S125), the control unit 10 acquires the voltage Vc of the secondary battery unit 50 (S126) and acquires the current Ic of the secondary battery unit 50 (S127). The control unit 10 determines whether or not the acquired current Ic is greater than or equal to a predetermined threshold value (S128). The threshold value can be set to a value required to accurately calculate the internal resistance Rzx.

  When the acquired current Ic is equal to or higher than the predetermined threshold value (YES in S128), the control unit 10 calculates the internal resistance Rzx (S129) and ends the process. The internal resistance Rzx can be calculated by, for example, Rzx=(Vc-Vb)/(Ic-Ib). When the acquired current Ic is not equal to or higher than the predetermined threshold value (NO in S128), the control unit 10 ends the process without performing the process of step S129.

  The deterioration determination device (battery monitoring device 100) of the present embodiment can also be realized using a general-purpose computer including a CPU (processor), a RAM (memory), and the like. That is, as shown in FIGS. 11 to 14, a computer program that defines the procedure of each process is loaded into a RAM (memory) provided in the computer, and the computer program is executed by a CPU (processor). Thus, the deterioration determination device (battery monitoring device 100) can be realized.

  In the above-described embodiment, the secondary battery unit 50 is described as a lithium ion battery, but the secondary battery unit 50 is not limited to a lithium ion battery, and may be provided for, for example, a nickel hydrogen battery or a nickel cadmium battery. can do.

  The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

10 Control Section 11 Voltage Acquisition Section 12 Current Acquisition Section 13 Temperature Acquisition Section 14 Switching Determination Section 15 Standby Time Identification Section 16 First Resistance Calculation Section 17 Second Resistance Calculation Section 18 Deterioration Determination Section 19 Ratio Calculation Section 20 Overvoltage Calculation Section 21 Charging Rate calculation unit 22 Correction unit 23 Storage unit 24 Timer 50 Secondary battery unit 51 Cell 52 Voltage sensor 53 Current sensor 54 Temperature sensor 100 Battery monitoring device

Claims (12)

A deterioration determination device for determining deterioration of a secondary battery,
A voltage acquisition unit that acquires the voltage of the secondary battery,
A current acquisition unit for acquiring the current of the secondary battery,
A switching determination unit that determines whether charging or discharging of the secondary battery is switched based on the current acquired by the current acquisition unit,
A first resistor that calculates a first internal resistance of the secondary battery based on the voltage acquired by the voltage acquisition unit and the current acquired by the current acquisition unit when the switching determination unit determines that charge/discharge is switched. A calculator,
The second internal resistance of the secondary battery is calculated based on the voltage acquired by the voltage acquisition unit, the current acquired by the current acquisition unit, and the equivalent circuit model of the secondary battery regardless of whether charge/discharge is switched. A second resistance calculator,
A deterioration determination unit that determines the presence or absence of deterioration of the secondary battery based on the first internal resistance calculated by the first resistance calculation unit and the second internal resistance calculated by the second resistance calculation unit ;
A ratio calculation unit that calculates a ratio of the first internal resistance to the second internal resistance ,
The deterioration determination unit,
You determine the presence or absence of deterioration of the secondary battery based on the magnitude of the ratio calculated by the ratio calculation unit deterioration determination device. A deterioration determination device for determining deterioration of a secondary battery,
A voltage acquisition unit that acquires the voltage of the secondary battery,
A current acquisition unit for acquiring the current of the secondary battery,
A switching determination unit that determines whether charging or discharging of the secondary battery is switched based on the current acquired by the current acquisition unit,
A first resistor that calculates a first internal resistance of the secondary battery based on the voltage acquired by the voltage acquisition unit and the current acquired by the current acquisition unit when the switching determination unit determines that charge/discharge is switched. A calculator,
The second internal resistance of the secondary battery is calculated based on the voltage acquired by the voltage acquisition unit, the current acquired by the current acquisition unit, and the equivalent circuit model of the secondary battery regardless of whether charge/discharge is switched. A second resistance calculator,
A deterioration determination unit that determines the presence or absence of deterioration of the secondary battery based on the first internal resistance calculated by the first resistance calculation unit and the second internal resistance calculated by the second resistance calculation unit;
An overvoltage calculation unit that calculates an overvoltage of the secondary battery based on the current acquired by the parameters of the equivalent circuit model and the current acquisition unit;
Equipped with
The second resistance calculator is
The deterioration determining apparatus that to calculate the second internal resistance of the secondary battery based on the obtained current with overvoltage and the current acquisition unit calculated by the overvoltage calculation unit. The deterioration determination unit,
Depending on either whether or not the threshold value or more of the ratio calculation unit different thresholds calculated ratio of more, the deterioration determination device according to judges claim 1 the deterioration state of the secondary battery in a plurality of stages .. The ratio calculation unit calculates a repetition said ratio,
The deterioration determination unit,
The secondary battery is determined to be in a deterioration state corresponding to the threshold value when the number of times the ratio calculated by the ratio calculation unit is equal to or greater than the threshold value is equal to or greater than a predetermined number of times. Deterioration determination device. An overvoltage calculation unit for calculating an overvoltage of the secondary battery based on the current acquired by the parameter of the equivalent circuit model and the current acquisition unit,
The second resistance calculator is
Claim 1 for calculating a second internal resistance of the secondary battery based on the current obtained by the overvoltage overvoltage was calculated by the calculation unit and the current acquisition unit, according to any one of claims 3 or claim 4 Deterioration determination device. A storage unit that stores related information that associates each of the temperature and the charging rate of the secondary battery with the parameter,
A temperature acquisition unit for acquiring the temperature of the secondary battery,
A charging rate calculation unit that calculates the charging rate of the secondary battery,
A temperature correction unit that corrects the parameter based on the temperature acquired by the temperature acquisition unit, the charging rate calculated by the charging rate calculation unit, and the related information stored in the storage unit;
The overvoltage calculation unit,
The deterioration determination device according to claim 5, wherein the overvoltage of the secondary battery is calculated based on the parameter corrected by the correction unit.   7. The initialization unit that initializes a calculation state in the equivalent circuit model that occurs when the overvoltage is calculated when the switching determination unit determines that charging/discharging is switched. Deterioration determination device. In the impedance spectrum of the secondary battery, a diffusion impedance resulting from the diffusion process of a predetermined ion, a specifying unit for specifying the standby time based on the boundary frequency region contributing to the impedance of the secondary battery,
The first resistance calculation unit,
When it is determined that there is charge/discharge switching in the switching determination unit, the secondary battery of the secondary battery based on the voltage acquired by the voltage acquisition unit and the current acquired by the current acquisition unit after the standby time specified by the specification unit claim 1 for calculating a first internal resistor, the deterioration determination device according to any one of claims 7 claims 3. A computer program for causing a computer to determine deterioration of a secondary battery,
Computer,
A voltage acquisition unit that acquires the voltage of the secondary battery,
A current acquisition unit for acquiring the current of the secondary battery,
A switching determination unit that determines whether charging or discharging of the secondary battery is switched based on the acquired current,
A first resistance calculator that calculates a first internal resistance of the secondary battery based on the acquired voltage and current when it is determined that charging/discharging is switched,
A second resistance calculation unit that calculates the second internal resistance of the secondary battery based on the acquired voltage and current and the equivalent circuit model of the secondary battery regardless of whether charge/discharge is switched ;
A deterioration determination unit that determines whether or not the secondary battery is deteriorated based on the calculated first internal resistance and second internal resistance ;
To function as a ratio calculation unit for calculating the first internal resistance ratio of the second internal resistor,
The deterioration determination unit,
Computer program based on the magnitude of the calculated ratio determine the presence or absence of deterioration of the secondary battery. A computer program for causing a computer to determine deterioration of a secondary battery,
Computer,
A voltage acquisition unit that acquires the voltage of the secondary battery,
A current acquisition unit for acquiring the current of the secondary battery,
A switching determination unit that determines whether charging or discharging of the secondary battery is switched based on the acquired current,
A first resistance calculation unit that calculates a first internal resistance of the secondary battery based on the acquired voltage and current when it is determined that charging/discharging is switched,
A second resistance calculation unit that calculates the second internal resistance of the secondary battery based on the acquired voltage and current and the equivalent circuit model of the secondary battery regardless of whether charge/discharge is switched;
A deterioration determination unit that determines whether or not the secondary battery is deteriorated based on the calculated first internal resistance and second internal resistance;
An overvoltage calculation unit that calculates an overvoltage of the secondary battery based on the parameters of the equivalent circuit model and the acquired current;
And let it work,
The second resistance calculator is
A computer program for calculating a second internal resistance of the secondary battery based on the calculated overvoltage and the acquired current. A deterioration determination method for determining deterioration of a secondary battery,
The voltage acquisition unit acquires the voltage of the secondary battery,
The current acquisition unit acquires the current of the secondary battery,
Based on the acquired current, the switching determination unit determines the presence or absence of switching of charge and discharge of the secondary battery,
When it is determined that charging/discharging is switched, the first resistance calculation unit calculates the first internal resistance of the secondary battery based on the acquired voltage and current,
The second resistance calculation unit calculates the second internal resistance of the secondary battery based on the acquired voltage and current and the equivalent circuit model of the secondary battery regardless of whether charge/discharge is switched ,
A deterioration determination unit determines whether or not the secondary battery is deteriorated based on the calculated first internal resistance and second internal resistance ,
The ratio calculator calculates a ratio of the first internal resistance to the second internal resistance,
The deterioration determination unit,
Deterioration determination method for determining the presence or absence of deterioration of the secondary battery based on the magnitude of the calculated ratio. A deterioration determination method for determining deterioration of a secondary battery,
The voltage acquisition unit acquires the voltage of the secondary battery,
The current acquisition unit acquires the current of the secondary battery,
Based on the acquired current, the switching determination unit determines the presence or absence of switching of charge and discharge of the secondary battery,
When it is determined that charging/discharging is switched, the first resistance calculation unit calculates the first internal resistance of the secondary battery based on the acquired voltage and current,
The second resistance calculator calculates the second internal resistance of the secondary battery based on the acquired voltage and current and the equivalent circuit model of the secondary battery regardless of whether charge/discharge is switched,
A deterioration determination unit determines whether or not the secondary battery is deteriorated based on the calculated first internal resistance and second internal resistance,
An overvoltage calculation unit calculates an overvoltage of the secondary battery based on the parameters of the equivalent circuit model and the acquired current,
The second resistance calculator is
A deterioration determination method for calculating a second internal resistance of the secondary battery based on the calculated overvoltage and the acquired current.

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