JP2017175798A - Control unit of secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately suppress a site where current is concentrated from being locally deteriorated, in a secondary battery having, at the inside thereof, a structure where a positive electrode plate, a separator, and a negative electrode plate are stacked.SOLUTION: An ECU controls the charging/discharging of a battery cell having, at the inside thereof, a structure where a positive electrode plate, a separator, and a negative electrode plate are stacked. The ECU specifies a current concentration site at the inside of a battery cell using a charge/discharge current I and a current distribution estimation model during the charge/discharge of the battery cell, estimates a positive electrode potential VPat the current concentration site and a negative electrode potential VPat the current concentration site, and controls the charge/discharge current I such that the potential VPand the potential VPfall within a positive electrode protection range and a negative electrode protection range, respectively.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a technique for controlling charge / discharge of a secondary battery.

  Japanese Patent No. 576378 (Patent Document 1) discloses a controller that controls charging and discharging of a secondary battery. This controller estimates the positive electrode potential and the negative electrode potential from the state of the secondary battery, and the estimated positive electrode potential falls within the positive electrode protection range (the range between the positive electrode lower limit potential and the positive electrode upper limit potential), and the negative electrode potential is negative. Charging / discharging of the secondary battery is controlled so as to be within the protection range (a range of the negative electrode lower limit potential or higher and the negative electrode upper limit potential or lower). Thereby, deterioration of positive electrode material and negative electrode material is suppressed.

Japanese Patent No. 576378

  As represented by nickel-metal hydride batteries widely used as secondary batteries for hybrid vehicles, some secondary batteries have a structure in which a positive electrode plate, a separator, and a negative electrode plate are laminated. . In a secondary battery having such a laminated structure, the reaction within the electrode surface may be biased (uneven) depending on the resistance balance inside the battery. When the reaction in the electrode surface is biased, there is a concern that a region where current concentrates inside the battery and that the region is locally degraded. However, Patent Document 1 does not disclose any such problems and countermeasures.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a portion where current is concentrated in a secondary battery having a structure in which a positive electrode plate, a separator, and a negative electrode plate are laminated. It is to appropriately suppress local deterioration.

  A control device according to the present invention is a control device for a secondary battery having a structure in which a positive electrode plate, a separator, and a negative electrode plate are laminated in this order, and a current detection unit that detects a charge / discharge current of the secondary battery; And a control unit for controlling the charge / discharge current. During charging / discharging of the secondary battery, the control unit calculates a current flowing through the secondary battery for each of the plurality of regions arranged in the extending direction of the positive electrode plate and the negative electrode plate using the charge / discharge current, The maximum region in which the maximum current flows is identified from among the regions, and the potential of the positive electrode maximum portion, which is the portion included in the maximum region of the positive electrode plate, is within the predetermined positive electrode protection range and is included in the maximum region of the negative electrode plate The charge / discharge current is controlled so that the potential of the negative electrode maximum part, which is the part, falls within a predetermined negative electrode protection range.

  According to the said structure, a control part uses the charging / discharging electric current for every some area | region which arranges the electric current which flows through the inside of a secondary battery in the extension direction (direction along the electrode plate surface) of a positive electrode plate and a negative electrode plate. Calculate and identify the maximum area through which the maximum current flows. And a control part controls charging / discharging electric current so that the electric potential of the site | part (namely, site | part where an electric current concentrates) contained in the maximum area | region of each electrode plate may each fall in each protection range. Therefore, deterioration of the part where current concentrates is appropriately suppressed. As a result, in a secondary battery having a structure in which a positive electrode plate, a separator, and a negative electrode plate are laminated, local deterioration of a portion where current is concentrated can be appropriately suppressed.

  Preferably, the controller calculates a first potential change amount that is a voltage change amount of the maximum positive electrode portion derived from the metal resistance of the positive electrode plate during charging and discharging of the secondary battery, and the positive electrode protection range or the positive electrode maximum portion is calculated. While correcting the potential using the first potential change amount, the second potential change amount, which is the voltage change amount of the negative electrode maximum part derived from the metal resistance of the negative electrode plate, is calculated, and the potential of the negative electrode protection range or the negative electrode maximum part is calculated. Correction is performed using the second potential change amount.

  According to the said structure, it can suppress that charging / discharging is restrict | limited excessively by the influence of the electric potential change derived from metal resistance. Specifically, although the potential change due to the metal resistance does not affect the deterioration, there is no means for calculating the potential change due to the metal resistance in the past, so there is an excess corresponding to the margin corresponding to the potential change due to the metal resistance. However, the protection area of each pole had to be narrowed. On the other hand, according to the above configuration, the voltage change amount derived from the metal resistance at the portion where the current is concentrated is calculated for each electrode, and the protection region or potential of each electrode is corrected. Therefore, charge / discharge control that eliminates the influence of a potential change derived from metal resistance is possible as compared with the conventional case. As a result, it is possible to suppress the charge / discharge from being excessively limited by the influence of the potential change derived from the metal resistance.

1 is a block diagram schematically showing the configuration of a vehicle. It is a figure which shows the structure of a battery unit. It is a figure which shows schematically the internal structure of a battery cell. It is a figure which shows typically the positive electrode potential and negative electrode potential at the time of non-energization, at the time of discharge, and discharge. It is a figure which shows typically an example of the current pathway inside a battery cell at the time of charging / discharging. It is a figure which shows an example of a current distribution estimation model typically. It is a flowchart (the 1) which shows the process sequence which ECU performs. It is a flowchart (the 2) which shows the process sequence which ECU performs.

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

<Vehicle configuration>
FIG. 1 is a block diagram schematically showing a configuration of a vehicle 1 on which a secondary battery control device according to the present embodiment is mounted. FIG. 1 shows a configuration related to charge / discharge control of the electric system in the vehicle 1. Although the vehicle 1 shown in FIG. 1 is an electric vehicle, the vehicle to which the present invention can be applied is not limited to an electric vehicle, and can be applied to any electric vehicle equipped with a secondary battery such as a hybrid vehicle.

  The vehicle 1 includes a secondary battery system 10, a system main relay (SMR) 20, a power control unit (PCU) 30, a motor generator (MG) 40, and driving wheels. 50. The secondary battery system 10 includes a battery unit 100, a monitoring unit 200, and an electronic control unit (ECU) 300.

  The battery unit 100 includes a plurality of battery cells 110 (see FIG. 2) connected in series. As each battery cell 110, a secondary battery such as a lithium ion battery or a nickel metal hydride battery is typically used.

  Monitoring unit 200 includes a voltage sensor 210, a current sensor 220, and a temperature sensor 230. Voltage sensor 210 is configured to detect the voltage of each cell in battery unit 100 (hereinafter also referred to as “cell voltage VC”). The current sensor 220 is configured to be able to detect the charge / discharge current I of the secondary battery system 10. The temperature sensor 230 is configured to detect the temperature in the battery unit 100 (hereinafter also referred to as “battery temperature T”). Each sensor outputs a signal indicating the detection result to ECU 300.

  Hereinafter, when the sign of the charging / discharging current I is positive, it indicates that discharging is in progress, and when it is negative, it indicates that charging is being performed.

  The SMR 20 is electrically connected between the battery unit 100 and the PCU 30. The SMR 20 is turned on / off in response to a control signal from the ECU 300. Thereby, conduction | electrical_connection and interruption | blocking between the battery unit 100 and PCU30 are switched.

  PCU 30 includes, for example, a converter and an inverter (both not shown). The PCU 30 is configured to be capable of bi-directional power conversion between the battery unit 100 and the MG 40 in accordance with a switching command from the ECU 300. The converter is configured to perform bidirectional DC voltage conversion between the battery unit 100 and the inverter. The inverter is configured to perform bidirectional power conversion between DC power and AC power input / output to / from the MG 40.

  More specifically, the inverter converts DC power supplied from the battery unit 100 via the converter into AC power and supplies the AC power to the MG 40. Thereby, the MG 40 generates the driving force of the driving wheel 50. On the other hand, at the time of regenerative braking of vehicle 1, the inverter converts AC power (regenerative power) generated by MG 40 into DC power and supplies it to the converter. Thereby, the battery unit 100 is charged.

  ECU 300 includes a CPU (Central Processing Unit) (not shown), a memory 310, and an input / output interface (not shown). ECU 300 controls charging / discharging of battery unit 100 by controlling PCU 30 based on signals from each sensor and information stored in the memory. Note that at least a part of the ECU 300 may be configured by hardware such as an electronic circuit.

<Configuration of battery unit>
FIG. 2 is a diagram illustrating the configuration of the battery unit 100 in detail. Battery unit 100 includes a plurality of battery cells 110, a pair of end plates 112, a restraining band 114, and a plurality of bus bars 116. The number of cells is not particularly limited. The x axis, the y axis, and the z axis are orthogonal to each other. The upper vertical direction is the positive direction of the z-axis.

  Each of the plurality of battery cells 110 has a flat rectangular shape, for example. The plurality of battery cells 110 are arranged in the y direction so that the side surfaces having the largest area face each other with a distance therebetween. In FIG. 2, one end of the plurality of battery cells 110 arranged in the y direction is partially shown. A pair of end plates 112 (only one is shown in FIG. 2) are arranged so as to face one end and the other end in the y direction, respectively. The pair of end plates 112 are restrained by the restraining band 114 with all the battery cells 110 sandwiched therebetween.

  Each cell 110 has a positive electrode terminal and a negative electrode terminal, and is arranged so that the positive electrode terminal faces the negative electrode terminal of an adjacent cell. A positive electrode terminal of a certain cell and a negative electrode terminal of an adjacent cell are electrically connected by being fastened by a bus bar 116 using a bolt and a nut (both not shown). Thereby, in the battery unit 100, the some battery cell 110 is mutually connected in series.

<Internal configuration of battery cell>
FIG. 3 is a diagram schematically showing the internal configuration of the battery cell 110. As shown in FIG. 3, a positive electrode plate 130, a negative electrode plate 140, and a separator 150 are accommodated in the battery cell 110. The positive electrode plate 130 and the negative electrode plate 140 are laminated via the separator 150. That is, the positive electrode plate 130, the separator 150, and the negative electrode plate 140 are laminated in this order.

  FIG. 3 exemplarily shows a pair of positive electrode plate 130, separator 150, and negative electrode plate 140, but actually, a plurality of positive electrode plates 130 and negative electrode plates 140 are alternately stacked with separator 150 interposed therebetween. Hereinafter, as shown in FIG. 3, the direction in which the positive electrode plate 130 and the negative electrode plate 140 extend is also simply referred to as “extending direction”.

  The positive electrode plate 130 includes a metal positive electrode current collector 132 and a positive electrode active material 134 formed on the surface of the positive electrode current collector 132. The negative electrode plate 140 includes a metal negative electrode current collector 142 and a negative electrode active material 144 formed on the surface of the negative electrode current collector 142. The separator 150 is provided between the positive electrode plate 130 and the negative electrode plate 140 in a state immersed in the electrolytic solution.

  One end (left side in the example of FIG. 3) in the extending direction of the positive electrode plate 130 is connected to the positive electrode terminal. One end (right side in the example of FIG. 3) of the extending direction of the negative electrode plate 140 is connected to the negative electrode terminal.

Hereinafter, the potential of the positive electrode plate 130 is described as “positive electrode potential V ₍₊₎ ”, and the potential of the negative electrode plate 140 is described as “negative electrode potential V ₍₋₎ ”. Further, the potential of the positive electrode plate 130 when not energized is described as “positive electrode open potential OCP ₍₊₎ ”, and the potential of the negative electrode plate 140 when deenergized is described as “negative electrode open potential OCP ₍₋₎ ”.

<Positive electrode protection region and negative electrode protection region>
4 is not energized when the positive electrode potential _{V (+)} and negative potentials _{V (-)} and, during discharge of the positive electrode potential _{V (+)} and negative potentials _{V (-)} and the positive electrode potential at the time of charging _{V (+)} It is a figure which shows typically negative electrode potential V _(-) .

During non-energization (charge / discharge current I = 0), the positive electrode potential V ₍₊₎ becomes the positive electrode open potential OCP ₍₊₎ , and the negative electrode potential V ₍₋₎ becomes the negative electrode open potential OCP ₍₋₎ . The difference between the negative electrode potential V ₍₋₎ and the positive electrode potential V ₍₊₎ is the cell voltage VC.

During discharging (charging / discharging current I> 0), the positive electrode potential V ₍₊₎ is determined by the metal resistance of the positive electrode current collector 132 (hereinafter also referred to as “positive electrode metal resistance R _{M (+)} ”) and the positive electrode active material 134. This is lower than the positive electrode open-circuit potential OCP ₍₊₎ due to the influence of the charge transfer resistance (hereinafter also referred to as “positive electrode reaction resistance R _{C (+)} ” ₎ derived from this reaction. The negative electrode potential V ₍₋₎ is the charge resistance (hereinafter referred to as “negative electrode reaction”) derived from the metal resistance of the negative electrode current collector 142 (hereinafter also referred to as “negative electrode metal resistance R _{M (−)} ”) and the reaction with the negative electrode active material 144. The negative electrode open-circuit potential OCP ₍₋₎ is increased by the influence of the resistance R _{C (−)} ”.

At the time of charging (charge / discharge current I <0), the positive electrode potential V ₍₊₎ is greater than the positive electrode open-circuit potential OCP ₍₊₎ due to the influence of the positive electrode metal resistance R _{M (+)} and the positive electrode reaction resistance R _{C (+).} Will also increase. The negative electrode potential V ₍₋₎ is lower than the negative electrode open-circuit potential OCP ₍₋₎ due to the influence of the negative electrode metal resistance _{RM (−)} and the negative electrode reaction resistance _{RC (−)} .

The positive electrode active material 134 deteriorates when the positive electrode potential V ₍₊₎ decreases excessively or increases excessively. That is, the positive electrode potential V ₍₊₎ includes a positive electrode lower limit potential V _{(+) min} and a positive electrode upper limit potential V _{(+) max at} which the positive electrode active material 134 does not deteriorate. Therefore, in order to prevent the deterioration of the positive electrode, the positive electrode potential V ₍₊₎ is a region between the positive electrode lower limit potential V _{(+) min} and the positive electrode upper limit potential V _{(+) max} (hereinafter also referred to as “positive electrode protection region”). It is desirable to control (limit) the charge / discharge current I so as to be within the range.

The negative electrode active material 144 deteriorates when the negative electrode potential V ₍₋₎ decreases excessively or increases excessively. That is, the negative electrode potential V ₍₋₎ includes a negative electrode lower limit potential V _{(−) min} and a negative electrode upper limit potential V _{(−) max at} which the negative electrode active material 144 does not deteriorate. Therefore, in order to prevent the deterioration of the negative electrode, the negative electrode potential V ₍₋₎ is a region between the negative electrode lower limit potential V _{(−) min} and the negative electrode upper limit potential V _{(−) max} (hereinafter also referred to as “negative electrode protection region”). It is desirable to control (limit) the charge / discharge current I so as to be within the range.

<Deterioration suppression of current concentration parts>
As described above, the battery cell 110 has a structure in which the positive electrode plate 130, the separator 150, and the negative electrode plate 140 are stacked in this order. In the battery cell 110 having such a laminated structure, during charging / discharging, the reaction within the surface of the electrode plate (the positive electrode plate 130 and the negative electrode plate 140) is biased (unevenness) according to the resistance balance inside the battery cell 110. ) May occur.

  FIG. 5 is a diagram schematically illustrating an example of a current path inside the battery cell 110 during charging and discharging. As shown in FIG. 5, the current in the battery cell 110 includes a positive electrode terminal, a positive electrode current collector 132, a positive electrode active material 134, an electrolyte (including the separator 150), a negative electrode active material 144, a negative electrode current collector 142, a negative electrode It flows in the order of terminals.

  As shown in FIG. 5, the current path between the positive electrode terminal and the negative electrode terminal is distributed to each region on the surface of the electrode plate. At this time, if the reaction in the electrode plate surface is biased (uneven) according to the resistance balance inside the battery cell 110, a site where current is concentrated in the battery cell 110 is generated, and the site is locally There is concern about deterioration.

  Conventionally, there is no means for quantifying the reaction distribution in the electrode plate surface, and it has not been possible to identify a site where current is concentrated during charging and discharging. In addition, since the cell voltage VC detected by the voltage sensor 210 is constant regardless of the location where the current is concentrated, the reaction distribution on the electrode plate surface during charging / discharging cannot be detected from the cell voltage VC. There wasn't.

Therefore, ECU 300 according to the present embodiment stores a current distribution estimation model (see FIG. 6), which will be described later, in a memory in advance, and uses the charge / discharge current I and the current distribution estimation model inside the battery during charging / discharging. Specify the current concentration part. Then, ECU 300 estimates positive potential VP _{(+) at the} current concentration portion and negative potential VP ₍₋₎ at the current concentration portion, and each potential VP ₍₊₎ , VP ₍₋₎ at the current concentration portion is in the positive electrode protection range. The charge / discharge current I is controlled so as to be within the inner and negative electrode protection ranges. Thereby, deterioration of a current concentration part can be suppressed appropriately.

FIG. 6 is a diagram schematically illustrating an example of a current distribution estimation model. The current distribution estimation model shown in FIG. 6 is virtually divided into N regions (1st to Nth regions, where N is a natural number of 2 or more) arranged in the battery in the extending direction of the electrode plate (the direction along the electrode plate surface). to split, the positive electrode metal resistor _{R M} in each region _{(+) 1 ~R M (+} ) N, the positive electrode reaction resistance _{R C (+) 1 ~R C} (+) N, electrolyte resistance _{R L1} to R _LN , Negative electrode reaction resistances R _{C (−) 1 to} R _{C (−) N} , and negative electrode metal resistances R _{M (−) 1 to} R _{M (−) N} are respectively represented by resistance ladder circuits. The ECU 300 uses the charge / discharge current I detected by the current sensor 220 and the current distribution estimation model shown in FIG. to calculate the _{1 ~i N.} Each resistance shown in FIG. 6 is calculated using, for example, battery temperature T as a parameter.

  FIG. 7 is a flowchart showing a processing procedure performed by ECU 300. This flowchart is repeatedly executed at a predetermined cycle during charging / discharging of the battery cell 110.

  In step (hereinafter, step is abbreviated as “S”) 10, ECU 300 acquires charge / discharge current I and battery temperature T from monitoring unit 200.

In S11, ECU 300 calculates the above-described distribution currents i _{1 to} i _N using charge / discharge current I and the above-described current distribution estimation model (see FIG. 6). Since the specific method for calculating the distribution currents i _{1 to} i _N has already been described, detailed description thereof will not be repeated here.

In S12, ECU 300 determines whether or not there is a bias between distribution currents i _{1 to} i _N. If there is no bias between distribution currents i _{1 to} i _N (NO in S12), ECU 300 ends the process.

When there is a bias between distribution currents i _{1 to} i _N (YES in S12), ECU 300 specifies maximum value imax among distribution currents i _{1 to} i _{N in} S13, and maximum value imax is A part included in the flowing area (hereinafter also referred to as “maximum area”) is specified as a current concentration part.

In S14, ECU 300 estimates positive electrode potential VP ₍₊₎ and negative electrode potential VP _(-) of the current concentration portion specified in S13. For example, the ECU 300 calculates the potentials VP ₍₊₎ and VP ₍₋₎ using the following equations (1) and (2), respectively, during discharging.

VP ₍₊₎ = OCP _{(+) −} ΔV _{C (+)} (1)
VP ₍₋₎ = OCP ₍₋₎ + ΔV _{C (−)} (2)
The ECU 300 calculates the potentials VP ₍₊₎ and VP ₍₋₎ using the following equations (3) and (4) during charging.

VP ₍₊₎ = OCP ₍₊₎ + ΔV _{C (+)} (3)
VP ₍₋₎ = OCP ₍₋₎ −ΔV _{C (−)} (4)
In the expressions (1) and (3), “ΔV _{C (+)} ” is a potential change amount derived from the positive electrode reaction resistance at the current concentration portion. In the expressions (2) and (4), “ΔV _{C (−)} ” is a potential decrease amount derived from the negative electrode reaction resistance at the current concentration site. For example, when the third region in the model shown in FIG. 6 is specified as the current concentration part, ΔV _{C (+)} and ΔV _{C (−)} are calculated using the following equations (5) and (6). Can do.

ΔV _{C (+)} = i ₃ · R _{C (+) 3} (5)
ΔV _{C (−)} = i ₃ · R _{C (−) 3} (6)
In addition, the estimation method of each electric potential VP ₍₊₎ , VP _(-) is not limited above, You may make it estimate using another method.

In S15, ECU 300 determines whether or not positive potential VP ₍₊₎ of the current concentration portion and negative potential VP _{(−) of} the current concentration portion estimated in S14 are within the positive electrode protection range and the negative electrode protection range, respectively. Determine whether.

When positive electrode potential VP _{(+) at the} current concentration portion and negative electrode potential VP _{(−) at the} current concentration portion are within the positive electrode protection range and the negative electrode protection range, respectively (YES in S15), ECU 300 ends the process. To do.

When positive electrode potential VP _{(+) at the} current concentration portion does not fall within the positive electrode protection range, or when negative electrode potential VP _{(−) at the} current concentration portion does not fall within the negative electrode protection range (NO in S15), ECU 300 Restricts charging / discharging of the battery unit 100 at S16. Specifically, ECU 300 controls PCU 30 such that the magnitude of charge / discharge current I is lower than the current value. Thereby, the respective potentials VP ₍₊₎ and VP ₍₋₎ of the current concentration part are controlled so as to be within the positive electrode protection range and the negative electrode protection range, respectively.

As described above, the ECU 300 according to the present embodiment identifies a current concentration portion in the battery cell 110 using the charge / discharge current I and the current distribution estimation model (see FIG. 6) during charging / discharging of the battery unit 100. Then, the positive potential VP ₍₊₎ of the current concentration portion and the negative potential VP ₍₋₎ of the current concentration portion are estimated, and the potentials VP ₍₊₎ and VP _{(−) of} the current concentration portion are within the positive electrode protection range and the negative electrode, respectively. The charge / discharge current I is controlled so as to be within the protection range. Thereby, deterioration of a current concentration part can be suppressed appropriately. As a result, in the battery cell 110 having a structure in which the positive electrode plate 130, the separator 150, and the negative electrode plate 140 are stacked, local deterioration of the current concentration portion can be appropriately suppressed.

<Modification>
Originally, the positive electrode potential V ₍₊₎ includes a potential change amount ΔV _{M (+)} derived from the positive electrode metal resistance R _{M (+)} . This potential change amount ΔVM ₍₊₎ does not affect the deterioration of the positive electrode active material 134. However, in the prior art, since there was no means for calculating the potential change amount ΔV _{M (+)} , in order to suppress the deterioration of the positive electrode more appropriately, a margin corresponding to the potential change amount ΔV _{M (+)} is excessive. In addition, the positive electrode protection region had to be narrowed.

Similarly, the negative electrode potential V ₍₋₎ originally includes the potential change amount ΔV _{M (−)} derived from the negative electrode metal resistance R _{M (−)} . This potential change amount ΔV _{M (−)} does not affect the deterioration of the negative electrode active material 144. However, conventionally, since there is no means for calculating the potential change amount ΔV _{M (−)} , in order to suppress the deterioration of the negative electrode more appropriately, an excessive amount corresponding to the potential change amount ΔV _{M (−)} is excessive. In addition, the negative electrode protection region had to be narrowed.

In view of the above points, in the present modification, the potential change amounts ΔVP _{M (+)} and ΔVP _{M (−)} derived from the metal resistance at the current concentration portion of each pole are used using the current distribution estimation model shown in FIG. The protection area of each pole is expanded by an amount corresponding to the calculated potential change amounts ΔVP _{M (+)} and ΔVP _{M (−)} .

  FIG. 8 is a flowchart showing a processing procedure performed by the ECU 300 according to this modification. Of the steps shown in FIG. 8, the steps given the same numbers as the steps shown in FIG. 7 described above have already been described, and detailed description thereof will not be repeated here.

After estimating the positive electrode potential VP _{(+) at the} current concentration part and the negative electrode potential VP ₍₋₎ at the current concentration part in S14, the ECU 300 determines the positive electrode potential change amount derived from the positive metal resistance in the current concentration part in S20. ΔVP _{M (+)} and the negative electrode potential change amount ΔVP _{M (−)} derived from the negative electrode metal resistance at the current concentration portion are calculated using the current distribution estimation model shown in FIG. The positive electrode potential change amount ΔVP _{M (+)} is a value obtained by summing the products of the positive electrode metal resistance in each region from the positive electrode terminal to the current concentration portion and the current flowing through the positive electrode current collector 132 in each region. For example, in the model shown in FIG. 6, when the third region is a current concentration portion, the positive electrode potential change amount ΔVP _{M (+)} derived from the metal resistance of the current concentration portion is calculated using the following equation (7). The

ΔVP _{M (+)} = I ₁ · R _{M (+) 1} + I ₂ · R _{M (+) 2} + I ₃ · R _{M (+) 3} (7)
The negative electrode potential change amount ΔVP _{M (−)} can be calculated based on the same concept.

In S21, ECU 300 expands the positive electrode protection region by an amount corresponding to positive electrode potential change amount ΔV _{M (+)} calculated in S20, and negative electrode by an amount corresponding to negative electrode potential change amount ΔV _{M (−).} Enlarge the protection area. Specifically, the ECU 300 sets the positive electrode lower limit potential V _{(+) min} , the positive electrode upper limit potential V _{(+) max} , the negative electrode lower limit potential V _{(−) min} , and the negative electrode upper limit potential V _{(−) max} as follows: Correction is performed using equations (8), (9), (10), and (11).

_{V (+) min = V (} +) min -ΔV M (+) ... (8)
V _{(+) max} = V _{(+) max} + ΔV _{M (+)} (9)
_{V (-) min = V (} -) min -ΔV M (-) ... (10)
V _{(−) max} = V _{(−) max} + ΔV _{M (−)} (11)
The ECU 300 sets the charge / discharge current I so that the potentials VP ₍₊₎ and VP _{(−) of} the current concentration portion estimated in S14 are within the positive electrode protection range and the negative electrode protection range expanded in S21, respectively. Restrict (S15, S16).

As described above, the ECU 300 according to this modification expands the protection area of each pole by an amount corresponding to the potential changes ΔVP _{M (+)} and ΔVP _{M (−)} derived from the metal resistance at the current concentration portion of each pole. The charge / discharge current I is controlled so that the positive electrode potentials VP ₍₊₎ and VP _{(−) at} the current concentration portion are within the expanded protection region of each electrode. Therefore, charge / discharge control that eliminates the influence of a potential change derived from metal resistance is possible as compared with the conventional case. As a result, it is possible to suppress the charge / discharge current I from being excessively limited by the influence of the potential change derived from the metal resistance.

In this modification, the protection region of each pole is expanded by an amount corresponding to each potential change amount ΔVP _{M (+)} and ΔVP _{M (−).} Instead, each potential change amount ΔVP _M You may make it correct | amend each electric potential VP ₍₊₎ , VP _(-) of an electric current concentration site | part by the part corresponded to ₍₊₎ , ₍ DELTA ₎ VPM _(-) . For example, during discharge, the positive electrode potential VP ₍₊₎ at the current concentration portion is increased by the potential change amount ΔVP _{M (+) and} the negative potential VP ₍₋₎ at the current concentration portion is increased by the potential change amount ΔVP _{M (−).} During charging, the positive electrode potential VP ₍₊₎ at the current concentration portion is decreased by the potential change amount ΔVP _{M (+) and} the negative potential VP ₍₋₎ at the current concentration portion is decreased by the potential change amount ΔVP _{M (−).} You may make it increase only. Even if it does in this way, since the influence of the electric potential change derived from metal resistance can be excluded from each electric potential VP ₍₊₎ , VP _{(-) of} a current concentration site | part, charging / discharging electric current I is restrict | limited excessively. Can be suppressed.

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

  DESCRIPTION OF SYMBOLS 1 Vehicle, 10 Secondary battery system, 50 Driving wheel, 100 Battery unit, 110 Battery cell, 112 End plate, 114 Restraint band, 116 Bus bar, 130 Positive electrode plate, 132 Positive electrode collector, 134 Positive electrode active material, 140 Negative electrode plate 142 negative electrode current collector, 144 negative electrode active material, 150 separator, 200 monitoring unit, 210 voltage sensor, 220 current sensor, 230 temperature sensor, 300 ECU, 310 memory.

Claims (2)

A control device for a secondary battery having a structure in which a positive electrode plate, a separator and a negative electrode plate are laminated in this order,
A current detector for detecting a charge / discharge current of the secondary battery;
A controller for controlling the charge / discharge current,
The controller is configured to charge / discharge the secondary battery.
Using the charge / discharge current, the current flowing inside the secondary battery is calculated for each of a plurality of regions arranged in the extending direction of the positive electrode plate and the negative electrode plate,
Identify a maximum region through which a maximum current flows from the plurality of regions;
The potential of the positive electrode maximum portion, which is a portion included in the maximum region of the positive electrode plate, falls within a predetermined positive electrode protection range, and the potential of the negative electrode maximum portion, which is a portion included in the maximum region of the negative electrode plate, is predetermined. The control apparatus of a secondary battery which controls the said charging / discharging electric current so that it may be settled in a negative electrode protection range. The controller is configured to charge / discharge the secondary battery.
A first potential change amount that is a voltage change amount of the maximum positive electrode portion derived from the metal resistance of the positive electrode plate is calculated, and the potential of the positive electrode maximum portion or the positive electrode protection range is corrected using the first potential change amount. And
A second potential change amount that is a voltage change amount of the negative electrode maximum portion derived from the metal resistance of the negative electrode plate is calculated, and the potential of the negative electrode maximum portion or the negative electrode protection range is corrected using the second potential change amount. The control device for a secondary battery according to claim 1.

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