JP2019175704A - Charge control device, power storage device, charge control method for power storage element, and computer program - Google Patents

Abstract

To provide a charge control device in which a power storage element is suppressed from being deteriorated due to heat generation with increased resistance during charging, a power storage device, a charge control method for a power storage element, and a computer program.SOLUTION: A charge control device 4 includes: a first acquisition unit 42 acquiring current during charging of a power storage element that includes a positive electrode material represented by Li(NiMnCoM)O(M represents a metal element other than Li, Ni, Mn, and Co, and 0≤a≤1, 0≤b<1, 0≤c<1, a+b+c+d=1 and 0<x≤1.1 are satisfied, while a and c are not 0 at the same time); a first calculation unit 47 calculating a calorific value of the power storage element on the basis of the current; and a control unit 50 controlling current such that the temperature of the power storage element falls within a predetermined range, on the basis of the calorific value.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a charge control device that controls charging of a power storage element, a power storage device, a charge control method for a power storage element, and a computer program.

  Storage elements such as lithium ion secondary batteries have been used as power sources for mobile devices such as notebook computers, mobile phones, and shavers. In recent years, it has been used in a wide range of fields such as EV (electric vehicle), HEV (hybrid electric vehicle), and PHEV (plug-in hybrid electric vehicle) power supplies, and further higher energy density is required.

Conventionally, a layered rock-salt type lithium transition metal oxide (hereinafter referred to as a layered oxide) has been used as a positive electrode active material, and a composition has been studied in order to realize a high energy density of a power storage device. That is, it is intended to increase the charging capacity by increasing the amount of Li extracted until the same upper limit charging voltage is reached. Of layered oxide, for example, in the case of NCM represented by _{Li x (Ni a Co b Mn} c) O 2 (a + b + c = 1,0 <x ≦ 1.1), by increasing the content of Ni, the power storage Without increasing the upper limit charging voltage of the device, the amount of Li extracted is increased to increase the capacity.
However, a storage element using a layered oxide with a large amount of Li extracted tends to increase the resistance of the storage element due to the positive electrode on the low SOC (State of Charge) side and the high SOC side.

  In recent years, there has been a demand for improvement in rapid charging performance of power storage elements. Examples of the charging method include CC-CV (Constant Current-Constant Voltage) charging (for example, Patent Document 1), multi-stage CC charging (for example, Patent Document 2), and the like. In CC-CV charging, after performing constant current charging in which charging is performed at a constant current, constant voltage charging is performed in which the charging current is gradually decreased so that the terminal voltage maintains a value near the charging upper limit voltage. In multi-stage CC (Constant Current) charging, after charging to a specified charging voltage with a constant current, CC charging is performed with the charging current reduced stepwise.

Japanese Patent Laid-Open No. 5-111184 Japanese Patent Application Laid-Open No. 7-296853

T.A. Fuller, M.M. Doyle, and J.A. Newman, Journal of Electrochemical Society 141, p. 1-p. 10

  When the above layered oxide is used as the positive electrode active material and charging is performed in Patent Documents 1 and 2, etc., the resistance increases on the low SOC side or the high SOC side. There is a problem of deterioration.

  An object of the present invention is to provide a charge control device, a power storage device, a charge control method for a power storage element, and a computer program in which deterioration of the power storage element due to heat generation due to an increase in resistance during charging is suppressed.

The charge control device for a power storage device according to the present invention has Li _x (Ni _a Mn _b Co _c M _d ) O ₂ (M is a metal element other than Li, Ni, Mn, Co, 0 ≦ a ≦ 1, 0 ≦ b). <1, 0 ≦ c <1, a + b + c + d = 1, 0 <x ≦ 1.1, and a and c are not 0 at the same time) to obtain a current during charging of a storage element having a positive electrode active material An acquisition unit; a first calculation unit that calculates a heat generation amount of the power storage element based on the current; and a control that controls the current based on the heat generation amount so that the temperature of the power storage element falls within a predetermined range. A part.

  In the present invention, the heat generation amount of the power storage element is calculated, and the current is controlled so that the temperature of the power storage element falls within a predetermined range, so that deterioration of the power storage element due to heat generation due to an increase in resistance is suppressed. .

It is a block diagram which shows the structure of the vehicle and server which concern on 1st Embodiment. It is a perspective view of a battery module. It is a block diagram which shows the structure of BMU. It is explanatory drawing for demonstrating the calculation method of the emitted-heat amount. It is a flowchart which shows the procedure of the update process of the battery capacity of a control part. It is a flowchart which shows the procedure of the charge control process of a control part. It is a block diagram which shows the structure of BMU which concerns on 2nd Embodiment. It is a graph which shows an example of SOC-R data. Is a graph showing the relationship between the resistance and the li _x MeO ₂ of x. It is a flowchart which shows the procedure of the charge control process by a control part.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.

(Outline of this embodiment)
The control device according to the present embodiment includes Li _x (Ni _a Mn _b Co _c M _d ) O ₂ (M is a metal element other than Li, Ni, Mn, Co, 0 ≦ a ≦ 1, 0 ≦ b <1, A first acquisition unit that acquires a current during charging of a power storage element having a positive electrode active material represented by 0 ≦ c <1, a + b + c + d = 1, 0 <x ≦ 1.1, and a and c are not 0 at the same time; A first calculation unit that calculates a heat generation amount of the power storage element based on the current, and a control unit that controls the current based on the heat generation amount so that the temperature of the power storage element falls within a predetermined range. Prepare.

When the layered oxide is used as a positive electrode active material, the amount of extracted Li at the time of charging when the same charging upper limit voltage is set is increased by considering the composition of metal elements such as Ni, Mn, and Co. The capacity can be increased. At the end of charging when a large amount of Li is extracted, the resistance of the storage element increases for the following reason. Further, the resistance increases even in the initial stage of charging (on the low SOC side). In the said nonpatent literature 1, the Butler-former type | formula in the case of the insertion type electrode reaction to which the positive electrode of a layered oxide corresponds is shown. In this equation, the reaction resistance is proportional to the -1/2 power of the product of the Li ⁺ ion concentration in the solid phase of the positive electrode active material and the empty site concentration, that is, the deep discharge state and the occlusion where there are no empty sites in the solid phase. It is shown that the reaction resistance increases at a deep charge depth where almost no Li is present.

  According to the above configuration, the amount of heat generated by the power storage element is calculated, and the current is controlled so that the temperature of the power storage element falls within a predetermined range. .

  In the control device according to the present embodiment, the a satisfies 0.5 ≦ a ≦ 1.

  When a positive electrode active material having a high Ni content ratio is used for charging, the resistance increases on the low SOC side or the high SOC side. According to the above configuration, the heat generation amount of the power storage element is calculated, and the current is controlled so that the temperature of the power storage element falls within a predetermined range, so that deterioration of the power storage element due to heat generation due to an increase in resistance is suppressed. .

  The charge control device according to the present embodiment includes a second acquisition unit that acquires a terminal voltage of the power storage element, and a second calculation unit that calculates an SOC, wherein the first calculation unit includes the terminal voltage and the SOC. And the calorific value is calculated based on SOC-OCV (Open Circuit Voltage) characteristics.

  According to the above configuration, the amount of heat generated by the power storage element can be satisfactorily calculated by time-integrating the power obtained by multiplying ΔV, which is the difference between the terminal voltage and the OCV, and the current.

  The charge control device according to the present embodiment refers to the second calculation unit that calculates the SOC, and the relationship between the SOC and the internal resistance, and based on the SOC calculated by the second calculation unit, the internal resistance of the power storage element The first calculation unit calculates the amount of heat generation based on the internal resistance.

  According to the above configuration, the internal resistance is estimated with reference to the relationship between the SOC and the internal resistance, and the power based on the internal resistance and the current is integrated over time, whereby the heat generation amount of the power storage element is calculated favorably.

  The charge control device according to the present embodiment includes a third calculation unit that calculates a capacity of the power storage element based on the current, a terminal voltage of the power storage element, and an SOC-OCV characteristic, and the second calculation unit includes: The SOC is calculated based on the capacity.

  According to the above configuration, since the capacity of the power storage element is updated, the SOC is favorably calculated.

  The charge control device according to the present embodiment includes a fourth calculation unit that calculates the temperature of the power storage element based on the heat generation amount, the ambient temperature of the power storage element, the heat dissipation coefficient, and the heat capacity.

  According to the above configuration, it is possible to control the current by calculating the temperature change of the power storage element based on the difference between the heat generation amount and the heat dissipation amount, and to control the temperature of the power storage element satisfactorily.

  The power storage device according to this embodiment includes the power storage element and any one of the above-described charge control devices.

  According to the said structure, heat_generation | fever of an electrical storage element is suppressed and deterioration is suppressed.

The storage element charging control method according to the present embodiment includes Li _x (Ni _a Mn _b Co _c M _d ) O ₂ (M is a metal element other than Li, Ni, Mn, Co, 0 ≦ a ≦ 1, 0 ≦ b <1, 0 ≦ c <1, a + b + c + d = 1, 0 <x ≦ 1.1, and a and c are not 0 at the same time) to obtain a current during charging of the storage element having a positive electrode active material, The heat generation amount of the power storage element is calculated based on the current, and the current is controlled based on the heat generation amount so that the temperature of the power storage element falls within a predetermined range.

  According to the above configuration, it is possible to suppress deterioration of the power storage element due to heat generation accompanying the increase in resistance.

The computer program according to the present embodiment causes _a computer to store Li _x (Ni _a Mn _b Co _c M _d ) O ₂ (M is a metal element other than Li, Ni, Mn, Co, 0 ≦ a ≦ 1, 0 ≦ b). <1, 0 ≦ c <1, a + b + c + d = 1, 0 <x ≦ 1.1, and a and c are not 0 at the same time) to obtain a current during charging of the storage element having the positive electrode active material, A heat generation amount of the power storage element is calculated based on the current, and a process of controlling the current is executed based on the heat generation amount so that the temperature of the power storage element falls within a predetermined range.

  According to the above configuration, it is possible to suppress deterioration of the power storage element due to heat generation accompanying the increase in resistance.

(First embodiment)
Hereinafter, although the case where an electrical storage element is a lithium ion secondary battery used for motor vehicles is demonstrated, an electrical storage element is not limited to the lithium ion secondary battery of such a use.
FIG. 1 is a block diagram illustrating configurations of the vehicle 1 and the server 13 according to the first embodiment.
The vehicle 1 includes a storage element module (hereinafter referred to as a battery module) 3, a BMU (Battery Management Unit) 4, a load 5, a general ECU (Electronic Control Unit) 6, a communication unit 7, a voltage sensor 8, A current sensor 9 and a temperature sensor 10 are provided.

In the battery module 3, lithium ion secondary batteries (hereinafter referred to as batteries) 2 as a plurality of power storage elements are connected in series. The overall ECU 6 controls the entire power supply device of the vehicle 1. The overall ECU 6 also controls the engine when the vehicle 1 is an HEV vehicle or a gasoline vehicle.
The server 13 includes a communication unit 14 and a control unit 15.
The overall ECU 6 is connected to the control unit 15 via the communication unit 7, the network 12, and the communication unit 14. The overall ECU 6 transmits and receives data to and from the control unit 15 via the network 12.
In the present embodiment, any of the BMU 4, the overall ECU 6, and the control unit 15 functions as the charge control device of the present invention. Any of the BMU 4, the overall ECU 6, and the control unit 15 and the battery module 3 function as the power storage device of the present invention. Note that when the control unit 15 does not function as the charge control device, the vehicle 1 may not be connected to the server 13.
A plurality of battery modules 3 may be provided.
The BMU 4 may be a battery ECU.

The voltage sensor 8 is connected in parallel to the battery module 3 and outputs a detection result corresponding to the overall voltage of the battery module 3. The voltage sensor 8 is connected to terminals 23 and 23 (described later) of each battery 2, measures the voltage V ₁ between the terminals 23 and 23 of each battery 2, and is a battery that is the total value of V ₁ of each battery 2. A voltage V between leads 33 and 33 described later of the module 3 is detected.
The current sensor 9 is connected in series with the battery module 3 and detects the current I flowing through the battery module 3.
The temperature sensor 10 is disposed in the vicinity of the battery module 3 and detects the ambient temperature (atmosphere temperature) T _s of the battery module 3.

FIG. 2 is a perspective view of the battery module 3.
The battery module 3 includes a rectangular parallelepiped case 31 and a plurality of the batteries 2 accommodated in the case 31.

The battery 2 includes a rectangular parallelepiped case main body 21, a cover plate 22, a pair of terminals 23 and 23 provided on the cover plate 22 and having different polarities, a rupture valve 24, and an electrode body 25. The electrode body 25 is formed by laminating a positive electrode plate, a separator, and a negative electrode plate, and is accommodated in the case body 21.
The electrode body 25 may be obtained by winding a positive electrode plate and a negative electrode plate in a flat shape via a separator.

  The positive electrode plate is obtained by forming a positive electrode active material layer on a positive electrode substrate foil that is a plate-like (sheet-like) or long strip-like metal foil made of aluminum, an aluminum alloy, or the like. The negative electrode plate is obtained by forming a negative electrode active material layer on a negative electrode substrate foil that is a plate-like (sheet-like) or long strip-like metal foil made of copper, a copper alloy, or the like. The separator is a microporous sheet made of a synthetic resin.

The positive electrode active material used for the positive electrode active material layer is Li _x (Ni _a Mn _b Co _c M _d ) O ₂ (M is a metal element other than Li, Ni, Mn, Co, 0 ≦ a ≦ 1, 0 ≦ b <1, 0 ≦ c <1, a + b + c + d = 1, 0 <x ≦ 1.1, and a and c are not 0 at the same time). The positive electrode active material has a layered rock salt type crystal structure. The a preferably satisfies 0.5 ≦ a ≦ 1. In this case, the transition metal site contains a large amount of Ni. For this reason, the resistance of the positive electrode is increased in the high SOC region.
The positive electrode active material is preferably d = 0, and NCM represented by Li _x (Ni _a Co _c Mn _b ) O ₂ (a + b + c = 1, a ≧ 0.5, b ≧ 0, c ≧ 0, 0 <x ≦ 1.1). a is more preferably 0.6 or more, and further preferably 0.8 or more.
The positive electrode active material may be NCA in which M is Al, b = 0, and Li _x (Ni _a Co _c Al _d ) O ₂ (a + c + d = 1, a ≧ 0.5, c ≧ 0, d ≧ 0, 0 <x ≦ 1.1). a is more preferably 0.6 or more, and further preferably 0.8 or more.
In addition, in NCM or NCA, it is not limited to the case where metals other than Li and Ni are each made of two types of metals, and may be made of three or more types of metals. For example, a small amount of Ti, Nb, B, W, Zr, Ti, Mg, etc. may be included.
Hereinafter, the case where the positive electrode active material is NCM satisfying the above a satisfies 0.5 ≦ a ≦ 1 will be described.

  Examples of the negative electrode active material used for the negative electrode active material layer include carbon materials such as graphite and amorphous carbon (non-graphitizable carbon and graphitizable carbon), or silicon monoxide (SiO), silicon (Si), and tin. It is a material that causes an alloying reaction with lithium ions, such as (Sn).

Adjacent terminals 23 of adjacent batteries 2 of the battery module 3 have different polarities, and the terminals 23 are electrically connected to each other by a bus bar 32 so that a plurality of batteries 2 are connected in series.
Leads 33 and 33 for taking out electric power are provided at terminals 23 and 23 having opposite polarities of the battery 2 at both ends of the battery module 3.

  FIG. 3 is a block diagram showing a configuration of the BMU 4. The BMU 4 includes a control unit 41, a storage unit 52, an input unit 55, and an interface unit 56. These units are connected to each other via a bus so as to communicate with each other.

  The input unit 55 receives input of detection results from the voltage sensor 8, the current sensor 9, and the temperature sensor 10. The interface unit 56 includes, for example, a LAN interface and a USB interface, and communicates with other devices such as the integrated ECU 6 by wire or wireless.

The storage unit 52 is configured by, for example, a hard disk drive (HDD) and stores various programs and data. The storage unit 52 stores, for example, a charge control program 53 for executing a charge control process described later. The charge control program 53 is provided in a state stored in a computer-readable recording medium 60 such as a CD-ROM, DVD-ROM, or USB memory, and is stored in the storage unit 52 by being installed in the BMU 4. Alternatively, the charging control program 53 may be acquired from an external computer (not shown) connected to the communication network and stored in the storage unit 52.
The storage unit 52 also stores SOC-OCV data (SOC-OCV characteristics) 54 obtained in advance by experiments. This data may be appropriately updated by a regular method.

  The control unit 41 includes, for example, a CPU, a ROM, a RAM, and the like, and controls the operation of the BMU 4 by executing a computer program such as the charging control program 53 read from the storage unit 52. The control unit 41 functions as a processing unit that executes the charging control process by reading and executing the charging control program 53.

  Specifically, the control unit 41 includes a current acquisition unit 42, a voltage acquisition unit 43, a temperature acquisition unit 44, a battery capacity calculation unit 45, an SOC calculation unit 46, a heat generation amount calculation unit 47, a temperature calculation unit 48, and a determination unit 49. , And a current control unit 50.

Hereinafter, the charge control process according to the present embodiment will be described in detail. The case where the battery module 3 is used as one power storage element and the charging of the battery module 3 is controlled will be described.
Control unit 41 of the BMU4 obtains the current I during the charging of the battery module 3 calculates the calorific value to Q ₁ battery module 3 on the basis of said current I, based on the emitting amount of heat Q _1, the battery module 3 The current I is controlled so that the temperature falls within a predetermined range. Strictly speaking, the calorific value Q ₁ is preferably the internal calorific value of the battery module 3, but may not be the internal calorific value.

The voltage acquisition unit 43 acquires the voltage V between the leads 33 and 33 of the battery module 3 from the voltage sensor 8 during charging.
The current acquisition unit 42 acquires the current I from the current sensor 9 during charging.
The temperature acquisition unit 44 acquires the ambient temperature T _s of the battery module 3 from the temperature sensor 10.

The battery capacity calculation unit 45 acquires the voltage V before and after the start of charging from the voltage acquisition unit 43. The battery capacity calculation unit 45 acquires the current I from the current acquisition unit 42 and calculates the amount of electricity q by integrating the energized current over time.
The battery capacity calculation unit 45 obtains ΔSOC corresponding to ΔOCV with reference to the SOC-OCV data 54, with the difference in voltage V before and after the start of charging being ΔOCV that is the difference in OCV. The battery capacity calculation unit 45 performs current integration for a time corresponding to ΔSOC to obtain Δq. The battery capacity calculation unit 45 calculates the battery capacity based on ΔSOC and Δq. The battery capacity calculation method is not limited to this case.
The SOC calculation unit 46 acquires the current I from the current acquisition unit 42 as needed, calculates the amount of electricity q by integrating the energized current over time, and calculates the SOC by dividing the amount of electricity q by the battery capacity.

  The calorific value calculation unit 47 reads the OCV at the time of calculating the SOC from the SOC-OCV data 54.

FIG. 4 is an explanatory diagram for explaining a calorific value calculation method.
In FIG. 4, the horizontal axis represents SOC (%), and the vertical axis represents voltage (V). The OCV curve in FIG. 4 corresponds to the SOC-OCV data 54. The CCV curve in FIG. 4 is a voltage curve between the leads 33 and 33 at each time point (each SOC). The SOC at time t ₁ is SOC ₁ , and the SOC at time t ₂ is SOC ₂ .
In FIG. 4, performs a CC charging to SOC _3, it is doing the CV charge from SOC _3.

ΔV is calculated by the following equation (1).
ΔV = CCV−OCV (1)
However, the voltage calorific value calculation unit 47 at the time of calculating CCV: SOC calculates electric power P by the following formula (2), and calculates the calorific value Q ₁ from the time t ₁ to t ₂ by the following formula (3). To do. The calorific value Q ₁ can be obtained by integration.
P = ΔV × I (2)

The temperature calculation unit 48 calculates the temperature T ₂ by the following formula (4) as an example based on the ambient temperature T _s of the battery module 3 and the calorific value Q ₁ acquired by the temperature acquisition unit 44. Strictly speaking, the temperature T ₂ is preferably the internal temperature of the battery module 3, but may not necessarily be the internal temperature as long as the temperature is correlated with the battery module 3, such as the surface temperature of the module.

Where T ₂ : temperature of battery module 3 at time t ₂ T ₁ : temperature of battery module 3 at time t ₁ , previously calculated temperature x: heat dissipation coefficient C _p : heat capacity

In the equation (4), the temperature change is obtained by dividing the difference between the heat generation amount Q ₁ and the heat release amount by the heat capacity C _p .

The determination unit 49 determines whether or not the temperature T ₂ calculated by the temperature calculation unit is within a threshold range.
When the current control unit 50 determines that the temperature T ₂ is not within the threshold range, the current control unit 50 controls the current I so that the temperature of the battery module 3 falls within a predetermined range. For example, the current control unit 50 controls the current I so that the difference between the heat generation amount Q ₁ and the heat dissipation amount becomes 0 and the temperature change becomes 0.

Hereinafter, the charge control process will be described as the process of the control unit 41.
First, the battery capacity update process will be described. FIG. 5 is a flowchart illustrating the procedure of the battery capacity update process of the control unit 41.
The control unit 41 performs a battery capacity update process at a predetermined interval or an arbitrary interval. The control unit 41 performs a battery capacity update process when charging is started in a state where there is no load and the open-circuit voltage is stable.

The control unit 41 acquires the voltage V before and after charging from the voltage sensor 8 and acquires the current I from the current sensor 9 (S1).
The controller 41 refers to the SOC-OCV data 54 and reads ΔSOC corresponding to the difference (ΔOCV) in the voltage V before and after the start of charging. The control unit 41 calculates Δq by integrating the energized current for the time Δt corresponding to ΔSOC. The control unit 41 calculates the battery capacity based on Δq and ΔSOC (S2).
The control unit 41 stores the battery capacity in the storage unit 52, and the battery capacity is updated (S3).

Hereinafter, the charge control process will be described.
FIG. 6 is a flowchart showing the procedure of the charging control process of the control unit 41.
The control unit 41 acquires the voltage V from the voltage sensor 8 and the current I from the current sensor 9 at a predetermined interval or an arbitrary interval (S11).
The control unit 41 integrates the current with time to determine the quantity of electricity q, and divides this by the battery capacity read from the storage unit 52 to calculate the SOC (S12).

The control unit 41 refers to the SOC-OCV data 54 and reads SOC ₁ and SOC ₂ at the time t = t ₁ and t = t ₂ (see FIG. 4). The controller 41 uses the SOC-OCV data 54 and based on the difference ΔV between the CCV and the OCV between the SOC _{1 to} SOC ₂ (t _{1 to} t ₂ ), the calorific value Q is calculated by the above formulas (2) and (3). ₁ is calculated (S13).
The control unit 41 acquires the ambient temperature T _s of the battery module 3 from the temperature sensor (S14).

Based on the above equation (4), the control unit 41 calculates the temperature T ₂ of the battery module 3 at the time of t = t ₂ (S15).
Control unit 41 determines whether temperature T ₂ is within the threshold value (S16). If the control unit 41 it is determined that the temperature T ₂ is within the threshold (S16: YES), the process ends.
If the control unit 41 it is determined that the temperature T ₂ is not within the threshold (S16: NO), control the current I so that the temperature of the battery module 3 is within the threshold (S17), and ends the process.
The control unit 41 repeats the above processing at a predetermined interval or an arbitrary interval.

In the present embodiment, the calorific value Q ₁ of the battery module 3 is calculated, and the current I is controlled so that the temperature of the battery module 3 falls within a predetermined range. Deterioration is suppressed.

(Second Embodiment)
Hereinafter, the charge control process according to the present embodiment will be described in detail.
The control part 41 of BMU4 of 2nd Embodiment acquires the electric current I at the time of charge of the battery module 3, calculates SOC based on the electric current I, and estimates the internal resistance R based on SOC. Then, the heat generation amount Q ₁ of the battery module 3 is calculated based on the internal resistance R, and the current I is controlled based on the heat generation amount Q _{1 so} that the temperature of the battery module 3 falls within a predetermined range.

FIG. 7 is a block diagram showing the configuration of the BMU 4. In the figure, the same parts as those in FIG.
The control unit 41 of the second embodiment includes a current acquisition unit 42, a voltage acquisition unit 43, a temperature acquisition unit 44, a battery capacity calculation unit 45, an SOC calculation unit 46, an internal resistance estimation unit 57, a heat generation amount calculation unit 47, and a temperature calculation. Unit 48, determination unit 49, and current control unit 50.

The storage unit 52 is configured by, for example, a hard disk drive (HDD) and stores various programs and data. The storage unit 52 stores a charge control program 53 for executing the charge control process. The charge control program 53 is provided in a state stored in a computer-readable recording medium 60 such as a CD-ROM, DVD-ROM, or USB memory, and is stored in the storage unit 52 by being installed in the BMU 4. Alternatively, the charging control program 53 may be acquired from an external computer (not shown) connected to the communication network and stored in the storage unit 52.
The storage unit 52 also stores SOC-OCV data 54 and SOC-R data (relationship between SOC and internal resistance) 61 obtained in advance by experiments.

  The internal resistance estimation unit 57 estimates the internal resistance R with reference to the SOC-R data 61 based on the SOC calculated by the SOC calculation unit 46.

FIG. 8 is a graph showing an example of the SOC-R data 61. The horizontal axis is SOC (%), and the vertical axis is resistance (Ω). The positive electrode active material is NCM811 represented by Li (Ni _0.8 Co _0.1 Mn _0.1 ) O ₂ , and the molar ratio of Ni, Co, and Mn is 8: 1: 1. As shown in FIG. 8, the resistance is high on the low SOC side and on the high SOC side.

  FIG. 8 is a graph showing an example of the SOC-R data 61. The horizontal axis is SOC (%), and the vertical axis is resistance (Ω). The positive electrode active material is NCM811, and the molar ratio of Ni, Co, and Mn is 8: 1: 1. As shown in FIG. 8, the resistance is high on the low SOC side and on the high SOC side.

FIG. 9 shows the amount of electricity based on the SOC and the theoretical capacity of FIG. 8, and _x when Li _x MeO ₂ (Me is a molar ratio of Ni, Co, and Mn is 8: 1: 1) is obtained. It is a graph which shows the relationship with resistance. The horizontal axis is x, and the vertical axis is resistance (Ω). When x is 0.25 or less, the resistance increases abruptly. Therefore, it can be seen that the amount of generated heat can be effectively suppressed by performing the charge control process according to the present embodiment.

The calorific value calculation unit 47 calculates ΔV in the same manner as in the first embodiment.
The calorific value calculation unit 47 calculates electric power P by the following formula (5), and calculates the calorific value Q ₁ from the time point t ₁ to t ₂ by the following formula (6).
P = R ² × I (5)

The temperature calculation unit 48 calculates the temperature T ₂ by the above equation (4) based on the temperature T _s of the atmosphere of the battery module 3 acquired by the temperature acquisition unit 44 and the calorific value Q ₁ .

The determination unit 49 determines whether or not the temperature T ₂ calculated by the temperature calculation unit is within a threshold range.
When the current control unit 50 determines that the temperature T ₂ is not within the threshold range, the current control unit 50 controls the current I so that the temperature of the battery module 3 falls within a predetermined range.

Hereinafter, the charge control process will be described as the process of the control unit 41.
FIG. 10 is a flowchart showing the procedure of the charging control process by the control unit 41.
The control unit 41 acquires the voltage V before and after charging from the voltage sensor 8 at a predetermined interval or an arbitrary interval, and acquires the current I from the current sensor 9 (S21).
Control unit 41 obtains the electric quantity q by integrating the current time, which is divided by the battery capacity read from the storage unit 52, SOC ₁ at the time of _{t = t 1, t = t} 2, SOC 2 Is calculated. (S22).

Control unit 41 refers to the SOC-R data 61, reads the internal resistance between _{SOC 1 ~SOC 2 (t 1 ~t} 2), to estimate the internal resistance R of the section (S23).
The control unit 41 calculates the calorific value Q ₁ by the above formula (6) (S24).

The control unit 41 acquires the ambient temperature T _s of the battery module 3 from the temperature sensor (S25).
Based on the ambient temperature T _s and the heat generation amount Q ₁ , the control unit 41 calculates the temperature T ₂ at the time point t = t ₂ by the above equation (4) (S26).

Control unit 41 determines whether temperature T ₂ is within the threshold value (S27). If the control unit 41 it is determined that the temperature T ₂ is within the threshold (S27: YES), the process ends.
If the control unit 41 it is determined that the temperature T ₂ is not within the threshold (S27: NO), control the current I so that the temperature falls within the threshold (S28), and ends the process.
The control unit 41 repeats the above processing at a predetermined interval or an arbitrary interval.

In the present embodiment, the heat generation amount Q ₁ of the battery module 3 is calculated based on the internal resistance R, and the current I is controlled so that the temperature of the battery module 3 falls within a predetermined range. Thus, deterioration of the battery module 3 is suppressed.

  The present invention is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

The charging control device according to the present invention is not limited to being mounted on a vehicle, but can be applied to other power storage devices such as a railway regenerative power storage device and a solar power generation system. The charge control device according to the present invention can also be applied to mobile devices such as notebook computers, mobile phones, and shavers. Furthermore, it can be applied to a charger.
And an electrical storage element is not limited to a lithium ion secondary battery. The storage element may be another secondary battery, a primary battery, or an electrochemical cell such as a capacitor.
In the first embodiment and the second embodiment, when the battery module 3 is used as one power storage element, the SOC-OCV data 54 or the SOC-R data 61 is acquired and the charging of the battery module 3 is controlled. Although described, the present invention is not limited to this. The SOC-OCV data 54 or the SOC-R data 61 may be acquired for each battery 2 and charging of the battery 2 may be controlled separately.

In the first embodiment and the second embodiment, the case where a in Li _x (Ni _a Mn _b Co _c M _d ) O ₂ satisfies 0.5 ≦ a ≦ 1 has been described. It is not limited.

1 vehicle 2 battery (storage element)
3 Battery module (storage element)
4 BMU (Charge Control Device)
41 control unit 42 current acquisition unit (first acquisition unit)
43 Voltage acquisition unit (second acquisition unit)
44 Temperature acquisition unit (fourth calculation unit)
45 Battery capacity calculator (third calculator)
46 SOC calculation unit (second calculation unit)
47 Heat generation amount calculation unit (first calculation unit)
48 Temperature calculation part 49 Judgment part 50 Current control part (control part)
52 Storage Unit 53 Charge Control Program 54 SOC-OCV Data 57 Internal Resistance Estimation Unit (Estimation Unit)
60 Recording medium 61 SOC-R data 6 Integrated ECU
13 server 15 control unit

Claims (9)

Li _x (Ni _a Mn _b Co _c M _d ) O ₂ (M is a metal element other than Li, Ni, Mn, Co, 0 ≦ a ≦ 1, 0 ≦ b <1, 0 ≦ c <1, a + b + c + d = 1 , 0 <x ≦ 1.1, and a and c are not 0 at the same time), a first acquisition unit that acquires a current during charging of the storage element having a positive electrode active material,
A first calculation unit that calculates a heat generation amount of the power storage element based on the current;
A charge control device comprising: a control unit that controls current so that the temperature of the power storage element falls within a predetermined range based on the heat generation amount.   The charge control device according to claim 1, wherein the a satisfies 0.5 ≦ a ≦ 1. A second acquisition unit for acquiring a terminal voltage of the power storage element;
A second calculation unit for calculating the SOC,
The charge control device according to claim 1 or 2, wherein the first calculation unit calculates the amount of heat generation based on the terminal voltage, the SOC, and an SOC-OCV characteristic. A second calculation unit for calculating the SOC;
An estimation unit that refers to the relationship between the SOC and the internal resistance and estimates the internal resistance of the power storage element based on the SOC calculated by the second calculation unit;
The charge control device according to claim 1, wherein the first calculation unit calculates the amount of heat generation based on the internal resistance. A third calculator that calculates a capacity of the power storage element based on the current, a terminal voltage of the power storage element, and an SOC-OCV characteristic;
The charge control device according to claim 3 or 4, wherein the second calculation unit calculates the SOC based on the capacity.   6. The charge control according to claim 1, further comprising a fourth calculation unit that calculates a temperature of the power storage element based on the heat generation amount, an ambient temperature of the power storage element, a heat dissipation coefficient, and a heat capacity. apparatus. The power storage element;
A power storage device comprising: the charge control device according to any one of claims 1 to 6. Li _x (Ni _a Mn _b Co _c M _d ) O ₂ (M is a metal element other than Li, Ni, Mn, Co, 0 ≦ a ≦ 1, 0 ≦ b <1, 0 ≦ c <1, a + b + c + d = 1 , 0 <x ≦ 1.1, and a and c are not 0 at the same time)
Calculate the heat generation amount of the electricity storage element based on the current,
A charge control method for a storage element, wherein the current is controlled so that the temperature of the storage element falls within a predetermined range based on the heat generation amount. On the computer,
Li _x (Ni _a Mn _b Co _c M _d ) O ₂ (M is a metal element other than Li, Ni, Mn, Co, 0 ≦ a ≦ 1, 0 ≦ b <1, 0 ≦ c <1, a + b + c + d = 1 , 0 <x ≦ 1.1, and a and c are not 0 at the same time)
Calculate the heat generation amount of the electricity storage element based on the current,
A computer program that executes a process of controlling current so that the temperature of the power storage element falls within a predetermined range based on the heat generation amount.

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