Information processing apparatus, program, and impedance estimation method

Abstract

To provide an information processing apparatus, a program, and an impedance estimation method, which can estimate an impedance characteristic of a secondary battery having a hysteresis characteristic.SOLUTION: An information processing apparatus includes an intra-active material charge carrier distribution calculation section, a hysteresis variable calculation section, and an impedance calculation section. The intra-active material charge carrier distribution calculation section calculates a charge carrier distribution inside an active material particle included in a secondary battery. The hysteresis variable calculation section calculates a hysteresis variable representing a voltage characteristic depending on a charge / discharge history of the secondary battery on the basis of the charge carrier distribution. The impedance calculation section calculates an impedance of the secondary battery on the basis of a first impedance in a first charge / discharge history state, a second impedance in a second charge / discharge history state, and the hysteresis variable.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present embodiment relates to an information processing device, a program, and an impedance estimation method. [Background technology]

[0002] A battery model that can quickly and accurately represent the impedance characteristics of a battery is desired. It is known that secondary batteries exhibit a hysteresis phenomenon in which the impedance characteristics vary depending on the charge / discharge history. Therefore, there is a need for an information processing device and an impedance estimation method that can reproduce the impedance characteristics of secondary batteries with hysteresis characteristics. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-90322 [Non-patent literature]

[0004] [Non-Patent Document 1] Norio Takami et al., “Lithium Diffusion in Li4 / 3Ti5 / 3O4 Particles during Insertion and Extraction”, Journal of Electrochemical Society, Vol. 158(6), A725-A730, (2011). Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an information processing device, a program, and an impedance estimation method that are capable of estimating the impedance characteristics of a secondary battery having hysteresis characteristics. [Means for solving the problem]

[0006] An information processing device according to an embodiment includes an active material charge carrier distribution calculation unit, a hysteresis variable calculation unit, and an impedance calculation unit. The active material charge carrier distribution calculation unit calculates the charge carrier distribution inside active material particles included in a secondary battery. The hysteresis variable calculation unit calculates a hysteresis variable representing voltage characteristics that depend on the charge and discharge history of the secondary battery based on the charge carrier distribution. The impedance calculation unit calculates the impedance of the secondary battery based on a first impedance in a first charge and discharge history state, a second impedance in a second charge and discharge history state, and the hysteresis variable. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating an example of an information processing system 1. FIG. [Figure 2] 1 is a schematic diagram showing an example of the distribution of charge carriers in an active material particle. [Figure 3] 1 is a schematic diagram showing an example of the distribution of charge carriers in an active material particle. [Figure 4] 3 is a schematic diagram showing an example of a change in distribution of charge carriers near the surface of an active material particle in a negative electrode. [Figure 5] FIG. 2 is a schematic diagram showing the relationship between active material particles and moving charge carriers when further charging / discharging is performed based on various charge / discharge histories. [Figure 6] FIG. 2 is a schematic diagram showing the relationship between active material particles and moving charge carriers when further charging / discharging is performed after a predetermined charging / discharging history. [Figure 7] 10 is an example of a flowchart for calculating a hysteresis variable. [Figure 8] This is a foster-type equivalent circuit model. [Figure 9] 1 is a graph showing changes in overvoltage over time. [Figure 10] FIG. 1 is a schematic diagram illustrating an example of an information processing system. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings. Hereinafter, elements that are the same as or similar to elements already described will be assigned the same or similar reference numerals, and duplicate descriptions will generally be omitted. Furthermore, the drawings are schematic or conceptual, and the relationship between the thickness and width of each illustrated part, the ratio of the size between parts, and other factors may not necessarily be the same as in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be expressed differently in different drawings.

[0009] (First embodiment) Fig. 1 is an example of a schematic diagram of an information processing system 1 according to this embodiment. As illustrated in Fig. 1, the information processing system 1 includes an information processing device 100 and a parameter storage unit 140 that stores parameters related to information processing by the information processing device 100. The information processing device 100 includes a data acquisition unit 110, an estimation unit 120, and an output unit 130.

[0010] The information processing device 100 is, for example, a processing device (computer) such as a server, and is capable of communicating with the parameter storage unit 140 via a wired or wireless network.

[0011] The data acquisition unit 110 may correspond to, for example, an input / output I / F (interface), a communication I / F, etc., and a processor. Here, the processor is typically a CPU (Central Processing Unit) and / or a GPU (Graphics Processing Unit), but may also be a microcomputer, an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), or other general-purpose or dedicated processor.

[0012] The data acquisition unit 110 acquires input data including measured values ​​of at least one of the current and voltage of the target secondary battery. The input data may be acquired directly from a measuring device such as an ammeter, or may be acquired remotely from a controller of the secondary battery via wired or wireless communication. The current, voltage, and / or power may be measured at multiple points in time during charging and / or discharging of the secondary battery. The input data may also include temperature data. The temperature data may indicate the measured temperature of the target secondary battery and / or the ambient temperature around it. The current / voltage / power / temperature data may include a value indicating the time of measurement in addition to the measured values ​​of current / voltage / power / temperature. The data acquisition unit 110 writes the input data to the parameter storage unit 140.

[0013] The estimation unit 120 may correspond to, for example, a processor. The estimation unit 120 reads input data, functions, fixed parameters, previous calculation results by various calculation units, and the like from the parameter storage unit 140. The estimation unit 120 estimates the voltage of the target secondary battery based on the read data. Details of the voltage estimation by the estimation unit 120 will be described later. The estimation unit 120 writes the estimated voltage to the parameter storage unit 140.

[0014] The output unit 130 is, for example, an input / output I / F (interface), a communication I / F, etc. The output unit 130 reads the voltage of the secondary battery estimated by the estimation unit 120 from the parameter storage unit 140 and outputs it. Here, "output" may mean presenting the voltage of the secondary battery estimated by the estimation unit 120 on an output device such as a display or speaker in the form of, for example, text, video, or audio, or may mean sending the voltage to an external device. Furthermore, the output unit 130 may automatically output the voltage of the secondary battery estimated by the estimation unit 120, or may output the voltage in response to a request from a user.

[0015] The parameter storage unit 140 may correspond to, for example, a memory, an auxiliary storage device, etc. Here, the auxiliary storage device may be a hard disk drive (HDD), a solid state drive (SSD), or other semiconductor memory, etc.

[0016] Input data is written to the parameter storage unit 140 by the data acquisition unit 110. Various functions (which may be curve data or a look-up table (LUT)) described below, which are used for voltage estimation by the estimation unit 120, and fixed parameters (for example, upper and lower limit voltages and initial values ​​of each parameter described below) are also written in advance to the parameter storage unit 140. Voltages are also written to the parameter storage unit 140 by the estimation unit 120. The data, such as voltages, stored in the parameter storage unit 140 is read out by the output unit 130.

[0017] The voltage estimation by the estimation unit 120 will be described in detail below.

[0018] First, the definitions of battery capacity and SOC (State of Charge) in this specification will be explained. Generally, the capacity of a lithium-ion secondary battery is calculated based on an upper limit voltage determined during charging and a lower limit voltage determined during discharging. However, in this specification, the capacity of the secondary battery is defined based on the open circuit voltage (OCV) of the secondary battery. Specifically, the capacity of the secondary battery is defined as the charge capacity when the secondary battery is charged until the OCV reaches a predetermined lower limit voltage, or the discharge capacity when the secondary battery is discharged until the OCV reaches a predetermined lower limit voltage. In this specification, the SOC of the secondary battery is defined as the ratio of the charge amount of the secondary battery to the capacity of the secondary battery, where 0% is when the OCV is at the lower limit voltage and 100% is when the OCV is at the upper limit voltage.

[0019] The estimation unit 120 estimates the voltage for each unit time. The estimation unit 120 may include an active material charge carrier distribution calculation unit 121 that calculates a charge carrier distribution inside active material particles included in the secondary battery, a hysteresis variable calculation unit 122 that calculates a hysteresis variable that represents voltage characteristics that depend on the charge and discharge history of the secondary battery based on the charge carrier distribution, an impedance calculation unit 123 that calculates the impedance of the secondary battery based on a first impedance in a first charge and discharge history state, a second impedance in a second charge and discharge history state, and the hysteresis variable, and a voltage calculation unit 124 that calculates the voltage of the secondary battery based on the impedance of the secondary battery and the current flowing through the secondary battery.

[0020] The active material charge carrier distribution calculation unit 121 calculates the distribution of charge carriers inside the active material particles of the target secondary battery (hereinafter referred to as "charge carrier distribution inside the active material") for each unit time. Specifically, it calculates the active material charge carrier distribution model at the second time point based on an active material charge carrier distribution model that represents the charge carrier distribution inside the active material at a first time point, the time difference from the first time point to a second time point that is later than the first time point, and input data of at least one of current and voltage.

[0021] FIG. 2 is a schematic diagram of an example of the distribution of charge carriers within an active material particle 10. For simplicity, a two-dimensional distribution will be used as an example. In the diagram, the gray areas indicate regions where charge carriers are present. FIG. 2 shows an example in which charge carriers are present near the outer shell of the active material particle 10. Below the schematic diagram of the active material particle 10, the horizontal axis indicates the distance r from the center of the active material particle 10, and the vertical axis indicates the charge capacity Q. FCC is the full charge capacity of the battery, n is the number of divisions on the horizontal axis of the two-dimensional distribution, and the upper limit of the vertical axis may be FCC / n. In this case, the area of ​​the gray area divided by FCC corresponds to the SOC. To create a more detailed model, a two-dimensional distribution in which the upper limit of the vertical axis varies depending on the distance r from the center of the active material particle 10, as shown in FIG. 3, may be considered.

[0022] Figure 4 is a schematic diagram showing the change in charge carrier distribution near the surface of an active material particle 10 in a negative electrode. As in Figure 2, the gray areas indicate regions where charge carriers 11 are present. Figure 4(a) shows the change during charging of a secondary battery. During charging, it can be assumed that charge carriers 11 are gradually inserted into the void regions of the active material particle 10 closest to the surface of the active material particle 10, where charge carriers 11 are absent. If charging is initiated from the state shown in the upper diagram of Figure 4(a) and continued for a certain period of time, charge carriers 11 are distributed and stored on the surface of the active material particle 10, as shown in the lower diagram of Figure 4(a). Meanwhile, Figure 4(b) shows the change during discharge of a secondary battery. During discharge, it can be assumed that charge carriers 11 present within the active material particle 10 are gradually removed from the charge carriers 11 closest to the surface of the active material particle 10. If discharging is initiated from the state shown in the upper diagram of Figure 4(b) and continued for a certain period of time, the state shown in the lower diagram of Figure 4(b) is achieved. In the lower diagram of FIG. 4(b), the dotted lines indicate the locations where charge carriers 11 are absent. Thus, the charge carrier distribution model within the active material is updated by inserting charge carriers 11 into the void regions of active material particles 10 closest to the surface of the active material particles 10 during charging of the secondary battery, and by detaching charge carriers 11 from the charge carriers 11 present within active material particles 10 closest to the surface of the active material particles 10 during discharging of the secondary battery. Hereinafter, in this specification, the void regions of active material particles 10 closest to the surface of the active material particles 10 will be referred to as "voids nearest the surface," and the charge carriers 11 present within active material particles 10 closest to the surface of the active material particles 10 will be referred to as "charge carriers nearest the surface." The positions of the voids / charge carriers 11 nearest the surface vary depending on the charge / discharge state.

[0023] The active material charge carrier distribution calculation unit 121 in this embodiment can calculate and update a charge carrier distribution model inside the active material particle 10 based on a current value given by measurement, etc. Specifically, first, the SOC change dSOC from a first time point to a second time point is calculated using the following equation (1):

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[0024] where i is the current, dt is the time difference from the first point in time to the second point in time, and FCC is the full charge capacity of the battery. The active material charge carrier distribution calculation unit 121 updates the active material charge carrier distribution model based on the obtained SOC change dSOC and the sign of the current. When the sign of the current i is positive (charging), charge carriers 11 are added to the voids closest to the surface by the amount of dSOC, and when the sign of the current i is negative (discharging), charge carriers 11 closest to the surface are deleted by the amount of dSOC, thereby updating the active material charge carrier distribution model. The updated active material charge carrier distribution model is output to the hysteresis variable calculation unit 122.

[0025] The hysteresis variable calculation unit 122 calculates the hysteresis variable based on the charge carrier distribution model within the active material. In this embodiment, it is assumed that hysteresis in the voltage characteristics occurs due to differences in the diffusion of charge carriers 11 depending on the charge carrier distribution model within the active material. The hysteresis variable calculation unit 122 calculates the hysteresis variable based on the distance that charge carriers 11 move within the active material particles 10 during charging and discharging of the secondary battery. Specifically, it is assumed that the diffusion resistance during charging is proportional to the ease with which charge carriers 11 are accommodated within the active material particles 10, which is proportional to the "distance between the voids nearest the surface and the surface." Furthermore, it is assumed that the diffusion resistance during discharging is proportional to the ease with which charge carriers 11 are released from the active material particles 10, which is proportional to the "distance between the charge carriers nearest the surface and the surface." Based on the above, the quantity related to the "distance between the voids nearest to the surface and the surface" during charging, and the quantity related to the "distance between the charge carriers 11 nearest to the surface and the surface" during discharging are calculated from the charge carrier distribution model in the active material and used as hysteresis variables.

[0026] Figure 5 is a schematic diagram showing the relationship between active material particles 10 and moving charge carriers 11 when further charging / discharging is performed after various charge / discharge histories. As in Figure 4, the gray areas indicate the areas where charge carriers 11 are present. Figure 5(a) conceptually shows the movement of charge carriers 11 when a secondary battery is charged from a state where the SOC is 0% to a state where it is adjusted to an arbitrary charge level (charge-adjusted state) and then further charged / discharged. Figure 5(a)(i) shows the case where further charging is performed from the charge-adjusted state. In this case, the "voids closest to the surface" are far from the surface, making it difficult for the active material particles 10 to accommodate the charge carriers 11. In other words, the diffusion resistance during charging is high. Figure 5(a)(ii) shows the case where discharging is performed from the charge-adjusted state. In this case, the "charge carriers closest to the surface" are present on the surface of the active material particles 10, making it easy for the active material particles 10 to release the charge carriers 11. In other words, the diffusion resistance during discharging is low.

[0027] Figure 5(b) conceptually shows the movement of charge carriers 11 when a secondary battery is discharged from a state where the SOC is 100% and adjusted to an arbitrary charge level (discharge-adjusted state) and then further charged / discharged. Figure 5(b)(i) shows the case where charging is performed from the discharge-adjusted state. At this time, the active material particles 10 easily accommodate charge carriers 11 because there are "voids closest to the surface" on the surface. In other words, the diffusion resistance during charging is small. Figure 5(b)(ii) shows the case where further discharging is performed from the discharge-adjusted state. At this time, the "charge carriers 11 closest to the surface" are far from the surface, so the active material particles 10 have difficulty releasing charge carriers 11. In other words, the diffusion resistance during discharge is large.

[0028] The following specifically describes a method for calculating the hysteresis variable in the state of the charge carrier distribution model in the active material as shown in Figure 6. Figure 6 shows the charge carrier distribution model in the active material after charging to SOC = 100%, discharging to a predetermined charge amount, and then charging to a predetermined amount, but the charge carrier distribution model in the active material to which the hysteresis variable calculation method described below can be applied is not limited to this. In Figure 6, the SOCm closest to the surface bl The center of gravity of the void is x G,blIn addition, the SOCm closest to the surface Li The center of gravity of the charge carriers 11 is x G,Li Let's say.

[0029] FIG. 7 is an example of a flowchart for calculating the hysteresis variable.

[0030] First, in S1, the center of gravity position x is calculated based on the charge carrier distribution model in the active material calculated by the charge carrier distribution calculation unit 121. G,bl and the center of gravity x G,Li and get.

[0031] Next, in S2, the obtained x G,bl and x G,Li Normalize x to 1 when charging and 0 when discharging. G,bl and x G,Li is the normalized value of x' G,bl and x' G,Li Calculate.

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[0032] where x G,bl,c and x G,bl,dc are the x values ​​at charge and discharge adjustment, respectively. G,bl and x G,Li,c and x G,Li,dc are the x values ​​at charge and discharge adjustment, respectively. G,Li x' G,bl and x' G,Li is 1 when charging and 0 when discharging.

[0033] Next, in S3, x' is calculated using the following formulas (4) and (5). G,bl and x' G,Li Each first-order lag x' G,bl.tl and x' G,Li,tl Calculate.

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number

[0034] where τ bl and τ Li is the change in the charge carrier distribution model in the active material. G,bl and x' G,Li is a time constant related to the rate of change of G,bl (t), x' G,Li (t), x' G,bl.tl (t), x' G,Li,tl (t) is x' G,bl , x' G,Li , x' G,bl.tl , x' G,Li,tl is a notation indicating that it is a function of t, and the same applies to the following equations.

[0035] Next, in S4, the value of a switching parameter sp that determines whether the battery is charging or discharging is determined. For example, when sp=0 and i(t)>0, it is determined that the battery has changed from a discharging state or a non-conducting state after discharging to a charging state, and sp is set to sp=1. When sp=1 and i(t)<0, it is determined that the battery has changed from a charging state or a non-conducting state after charging to a discharging state, and sp is set to sp=0.

[0036] Next, in S5, the value of sp is determined. If sp=1, it is determined that charging is in progress, and the process proceeds to S6a, where the hysteresis variable x hys as x' G,bl.tl Alternatively, if sp=0, it is determined that discharging is in progress, and the process proceeds to S6b, where the hysteresis variable x hys as x' G,Li,tl Select .

[0037] Finally, in S7, the hysteresis variable x calculated above is hys is output to the impedance calculation unit 123.

[0038] The impedance calculation unit 123 calculates the impedance of the secondary battery based on the first impedance in the first charge / discharge history state, the second impedance in the second charge / discharge history state, and the hysteresis variable. In this specification, the first charge / discharge history state is described as a charge combined state, and the second charge / discharge history state is described as a discharge combined state. Also, the first impedance is described as a value estimated from measurement data in the first charge / discharge history state, and the second impedance is described as a value estimated from measurement data in the second charge / discharge history state. Also, the impedance is expressed by resistance and capacitance. The resistance R in the charge combined state is c is estimated based on the measurement data of at least one of the current and voltage in the charging state, and the resistance R dc is estimated based on measurement data of at least one of the current and the voltage in the discharge matching state. c , resistance R dc and the hysteresis variable x obtained by the hysteresis variable calculation unit 122 hys Based on this, the resistance R of the equivalent circuit model of the secondary battery in any charge / discharge history state is calculated. Also, the capacitance C c is estimated based on measurement data of at least one of the current and voltage in the charging state, and the capacitance C dc is estimated based on measurement data of at least one of the current and the voltage in the discharge matching state. c , capacitance C dc and the hysteresis variable x hys The impedance calculation unit 123 may use the following formula (6) to calculate the resistance R, and the following formula (7) to calculate the capacitance C, based on the above formula.

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[0039] Here, the numerical values ​​of R, C, etc. used in the formula are stored in the parameter storage unit 140.

[0040] Voltage calculation unit 124 uses resistance R and capacitance C obtained by impedance calculation unit 123 and current i to calculate voltage v based on an equivalent circuit model in which impedance is expressed in terms of resistance and capacitance. For example, consider a Foster-type equivalent circuit model as shown in Fig. 8. In this case, voltage v(t) at time t is given by the following equations (8) to (10).

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[0041] Here, OCV is the open circuit voltage of the battery. For example, the relationship between SOC and OCV can be obtained in advance, and the OCV can be calculated for each SOC at each time. The SOC can be calculated using the current integration method shown in the following equation (11).

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[0042] Here, SOC0 is the SOC at time t=0.

[0043] Although the above example shows a Foster-type equivalent circuit model, any equivalent circuit model may be used. The resistance R and capacitance C for charging and discharging, which are stored in the parameter storage unit 140, can be estimated using the same equivalent circuit model as that used by the voltage calculation unit 124.

[0044] In this way, by taking the overvoltage hysteresis into consideration based on the charge / discharge history, the voltage of the secondary battery can be estimated accurately in a relatively short time. Note that the information processing device 100 described above is particularly suitable for a case where the voltage calculation unit 124 calculates the voltage of the secondary battery based on an equivalent circuit model including an overvoltage model of the secondary battery.

[0045] The following compares IV test data with the voltage estimation model according to this embodiment. Figure 9 is a graph showing the change in overvoltage over time. The vertical axis represents overvoltage, and the horizontal axis represents the time elapsed since the start of charging and discharging. Figure 9(a) is a graph showing the change in overvoltage over time when charging for 60 seconds at i = 60, 90, and 150 A, and Figure 9(b) is a graph showing the change in overvoltage over time when discharging for 60 seconds at i = 60, 90, and 150 A. The IV test data is plotted in white, while the dashed line a represents the estimation result when the hysteresis variable of the voltage estimation model according to this embodiment is applied to the equivalent circuit. The dotted line b represents the estimation result when the charge adjustment of the voltage estimation model according to this embodiment is applied to the equivalent circuit. The dotted line c represents the estimation result when the discharge adjustment of the voltage estimation model according to this embodiment is applied to the equivalent circuit. The secondary battery used in the IV test had a certain charge / discharge history (hysteresis). In FIG. 9, it can be seen that the open plots showing the IV test data closely match the dashed line a showing the estimation results when the hysteresis variable of the voltage estimation model according to this embodiment is applied to the equivalent circuit.

[0046] In this embodiment, the reference charge / discharge history is described as a charge-matched state and a discharge-matched state, but the reference charge / discharge history is not limited to this and can be any two different charge / discharge histories, and these charge / discharge histories can be referred to as a first charge / discharge history state and a second charge / discharge history state, respectively.

[0047] In this embodiment, the first and second impedances are described as values ​​estimated from measurement data in the first and second charge / discharge history states, but the first and second impedances are not limited to this and may be values ​​obtained from, for example, an external server.

[0048] In the description of this embodiment, the capacity of the secondary battery is defined based on the OCV, but it is not necessary to use the OCV as the standard. For example, the capacity of the secondary battery may be defined based on the value obtained by adding the OCV to the overvoltage.

[0049] In this embodiment, it is assumed that the diffusion resistance during charging and discharging depends on the ease with which charge carriers 11 are released to the active material particles 10 or the ease with which charge carriers 11 are stored in the active material particles 10. In the above embodiment, an example focusing on the active material particles of the negative electrode has been described, but a similar voltage estimation may be performed focusing on the positive electrode.

[0050] (Second embodiment) In this embodiment, the information processing device 200 performs hysteresis voltage estimation that takes battery degradation into consideration.

[0051] 10 is an example of a schematic diagram of an information processing system 2 in this embodiment. As illustrated in FIG. 10, the information processing system 2 includes an information processing device 200, a storage unit 240, and a degradation coefficient storage unit 250. The information processing device 200 includes a data acquisition unit 210, an estimation unit 220, and an output unit 230.

[0052] The estimation unit 220 reads input data, degradation coefficients, functions, fixed parameters, estimated voltages, etc. from the storage unit 240 and the degradation coefficient storage unit 250. The estimation unit 220 estimates the voltage of the target secondary battery based on the read data. The voltage estimation by the estimation unit 220 will be described in detail later. The estimation unit 220 writes the estimated voltage to the storage unit 240.

[0053] The estimation unit 220 may include an active material charge carrier distribution calculation unit 221 , a hysteresis variable calculation unit 222 , an impedance calculation unit 223 , and a voltage calculation unit 224 .

[0054] Similar to the active material charge carrier distribution calculation unit 121, the active material charge carrier distribution calculation unit 221 calculates the active material charge carrier distribution model of the target secondary battery for each unit time.

[0055] The hysteresis variable calculation unit 222 calculates the hysteresis variable x hys Calculate.

[0056] The impedance calculation unit 223 calculates the impedance of the secondary battery based on a deterioration coefficient related to the deterioration state of the secondary battery. That is, the impedance calculation unit 223 can calculate the resistance R and the capacitance C taking into account the deterioration state of the secondary battery. When calculating the resistance taking into account the deterioration of the secondary battery, the following formula (12) can be used.

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[0057] where x deg is the degradation factor of the resistor R. For example, x deg is stored in the deterioration coefficient storage unit 250, and the deterioration coefficient x is calculated according to an index that indicates the deterioration state of the secondary battery, such as the SOH. deg In addition, the rate of change in resistance due to degradation is R c and R dc If different, R c and R dc Each of the different degradation coefficients x c_deg and x dc_deg (Equation (13))

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[0058] Deterioration of capacitance can also be taken into consideration in a similar manner.

[0059] The voltage calculation unit 224 calculates an estimated value of the voltage v based on the resistance R and capacitance C obtained by the impedance calculation unit 223 and the current i.

[0060] In this way, the impedance calculation unit 223 calculates the resistance R and capacitance C taking into account the degree of deterioration of the secondary battery, and the voltage calculation unit 224 calculates an estimated value of the voltage v using these values, thereby allowing the information processing device 200 to perform hysteresis voltage estimation taking into account battery deterioration.

[0061] Although several embodiments have been described above, the present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

[0062] [Appendix 1] an active material charge carrier distribution calculation unit that calculates a charge carrier distribution inside an active material particle included in the secondary battery; a hysteresis variable calculation unit that calculates a hysteresis variable representing voltage characteristics that depend on a charge / discharge history of the secondary battery based on the charge carrier distribution; an impedance calculation unit that calculates the impedance of the secondary battery based on a first impedance in a first charge / discharge history state, a second impedance in a second charge / discharge history state, and the hysteresis variable; Information processing device.

[0063] [Appendix 2] a voltage calculation unit that calculates a voltage of the secondary battery based on an impedance of the secondary battery and a current flowing through the secondary battery; 2. The information processing device according to claim 1.

[0064] [Appendix 3] the voltage calculation unit calculates the voltage of the secondary battery based on an equivalent circuit model in which the impedance is expressed by a resistance and a capacitance. 3. The information processing device according to claim 2.

[0065] [Appendix 4] the voltage calculation unit calculates the voltage of the secondary battery based on an equivalent circuit model including an overvoltage model of the secondary battery; 4. An information processing device according to claim 2 or 3.

[0066] [Appendix 5] the active material charge carrier distribution calculation unit calculates a charge carrier distribution model inside the active material particles based on a current value related to the secondary battery. 5. The information processing device according to any one of appendices 1 to 4.

[0067] [Appendix 6] The charge carrier distribution model in the active material is During charging of the secondary battery, charge carriers are inserted into the void regions of the active material particles that are closest to the surfaces of the active material particles, During discharge of the secondary battery, charge carriers present in the active material particles are renewed by being removed from the charge carriers closest to the surfaces of the active material particles. 6. The information processing device according to claim 5.

[0068] [Appendix 7] the hysteresis variable calculation unit calculates the hysteresis variable based on a distance that charge carriers move inside the active material particles during charging and discharging of the secondary battery. 7. The information processing device according to any one of appendices 1 to 6.

[0069] [Appendix 8] the first charge / discharge history state is a state in which the secondary battery is charged from a 0% charge state to an arbitrary charge amount, The second charge / discharge history state is a state in which the secondary battery is discharged from a 100% charge state to an arbitrary charge state. 8. An information processing device according to any one of appendices 1 to 7.

[0070] [Appendix 9] a data acquisition unit that acquires a measurement value of at least one of a current and a voltage of the secondary battery; An information processing device according to any one of appendices 1 to 8.

[0071] [Appendix 10] the first impedance is a value estimated from measurement data in the first charge / discharge history state, The second impedance is a value estimated from measurement data in the second charge / discharge history state. 10. An information processing device according to any one of appendices 1 to 9.

[0072] [Appendix 11] the impedance calculation unit calculates the impedance of the secondary battery based on a deterioration coefficient related to a deterioration state of the secondary battery. An information processing device according to any one of appendices 1 to 10.

[0073] [Appendix 12] a step in which an intra-active material charge carrier calculation unit calculates a charge carrier distribution inside an active material particle included in the secondary battery; a hysteresis variable calculation unit calculating a hysteresis variable representing voltage characteristics depending on a charge / discharge history of the secondary battery based on the charge carrier distribution; an impedance calculation unit calculating an impedance of the secondary battery based on a first impedance in a first charge / discharge history state, a second impedance in a second charge / discharge history state, and the hysteresis variable; An impedance estimation method comprising:

[0074] [Appendix 13] The processing circuit Calculating the charge carrier distribution inside active material particles contained in the secondary battery; calculating a hysteresis variable representing a voltage characteristic dependent on a charge / discharge history of the secondary battery based on the charge carrier distribution; calculating an impedance of the secondary battery based on a first impedance in a first charge / discharge history state, a second impedance in a second charge / discharge history state, and the hysteresis variable; A program capable of calculating the voltage of the secondary battery based on the impedance of the secondary battery. [Explanation of symbols]

[0075] 1. Information Processing Systems 2. Information Processing Systems 10 Active material particles 11 Charge Carriers 100 Information processing device 110 Data Acquisition Unit 120 Estimation part 121 Calculation section for charge carrier distribution in active material 122 Hysteresis variable calculation section 123 Impedance calculation unit 124 Voltage calculation unit 130 Output section 140 Parameter storage unit 200 Information processing device 210 Data Acquisition Unit 220 Estimation section 221 Calculation of charge carrier distribution in active material 222 Hysteresis variable calculation section 223 Impedance calculation unit 224 Voltage calculation unit 230 Output section 240 Storage section 250 Degradation coefficient memory section

Claims

1. an active material charge carrier distribution calculation unit that calculates a charge carrier distribution inside an active material particle included in the secondary battery; a hysteresis variable calculation unit that calculates a hysteresis variable representing voltage characteristics that depend on a charge / discharge history of the secondary battery based on the charge carrier distribution; an impedance calculation unit that calculates the impedance of the secondary battery based on a first impedance in a first charge / discharge history state, a second impedance in a second charge / discharge history state, and the hysteresis variable; Information processing device.

2. a voltage calculation unit that calculates a voltage of the secondary battery based on an impedance of the secondary battery and a current flowing through the secondary battery; The information processing device according to claim 1 .

3. the voltage calculation unit calculates the voltage of the secondary battery based on an equivalent circuit model in which the impedance is expressed by a resistance and a capacitance. The information processing device according to claim 2 .

4. the voltage calculation unit calculates the voltage of the secondary battery based on an equivalent circuit model including an overvoltage model of the secondary battery; The information processing device according to claim 2 .

5. the active material charge carrier distribution calculation unit calculates a charge carrier distribution model inside the active material particles based on a current value related to the secondary battery. The information processing device according to claim 1 .

6. The charge carrier distribution model in the active material is During charging of the secondary battery, charge carriers are inserted into the void regions of the active material particles that are closest to the surfaces of the active material particles, During discharge of the secondary battery, charge carriers present in the active material particles are renewed by being removed from the charge carriers closest to the surfaces of the active material particles. The information processing device according to claim 5 .

7. the hysteresis variable calculation unit calculates the hysteresis variable based on a distance that charge carriers move inside the active material particles during charging and discharging of the secondary battery. The information processing device according to claim 1 .

8. the first charge / discharge history state is a state in which the secondary battery is charged from a 0% charge state to an arbitrary charge amount, The second charge / discharge history state is a state in which the secondary battery is discharged from a 100% charge state to an arbitrary charge state. The information processing device according to claim 1 .

9. a data acquisition unit that acquires a measurement value of at least one of a current and a voltage of the secondary battery; The information processing device according to claim 1 .

10. the first impedance is a value estimated from measurement data in the first charge / discharge history state, The second impedance is a value estimated from measurement data in the second charge / discharge history state. The information processing device according to claim 1 .

11. the impedance calculation unit calculates the impedance of the secondary battery based on a deterioration coefficient related to a deterioration state of the secondary battery. The information processing device according to claim 1 .

12. a step in which an intra-active material charge carrier calculation unit calculates a charge carrier distribution inside an active material particle included in the secondary battery; a hysteresis variable calculation unit calculating a hysteresis variable representing voltage characteristics depending on a charge / discharge history of the secondary battery based on the charge carrier distribution; an impedance calculation unit calculating an impedance of the secondary battery based on a first impedance in a first charge / discharge history state, a second impedance in a second charge / discharge history state, and the hysteresis variable; An impedance estimation method comprising:

13. The processing circuit Calculating the charge carrier distribution inside active material particles contained in the secondary battery; calculating a hysteresis variable representing a voltage characteristic dependent on a charge / discharge history of the secondary battery based on the charge carrier distribution; calculating an impedance of the secondary battery based on a first impedance in a first charge / discharge history state, a second impedance in a second charge / discharge history state, and the hysteresis variable; A program capable of calculating the voltage of the secondary battery based on the impedance of the secondary battery.

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