JP2020120555A - Control device, battery module, and electric vehicle - Google Patents

Abstract

To provide a control device capable of performing charge and discharge control suitable for a determined state by determining a local state of an electrode.SOLUTION: The control device includes: an acquisition unit (20) for acquiring a measured value of load or strain at a plurality of positions on a predetermined surface of a housing of a secondary battery (2); and a control unit (25) for controlling charge and discharge of the secondary battery based on a change in the load or the strain with respect to a charging rate of the secondary battery in each of the positions.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device, a battery module, and an electric vehicle.

Conventionally, a surface pressure distribution sensor is installed between the lithium ion secondary batteries that make up the assembled battery, and based on the measured value of this surface pressure distribution sensor, the presence or absence of lithium deposition and the deterioration state of the lithium ion secondary battery are detected. What is detected is known (for example, refer to Patent Document 1).

JP, 2013-020826, A

Regarding the state of the lithium-ion secondary battery, SOC (State Of Charge) and SOH (States Of Health) may have an in-plane distribution due to the current density distribution due to the structure of the electrode such as the individual difference in the thickness of the electrode. Are known. On the other hand, the conventional SOC estimation method based on the OCV (Open Circuit Voltage)-SOC characteristic is to average the entire electrode having the SOC distribution, and therefore to manage the local SOC and SOH of the electrode. I couldn't do it.

Aspects of the present invention have been made in consideration of such circumstances, and a control device, a battery module, which can determine a local state of an electrode and can perform charge/discharge control suitable for the determined state, Another object is to provide an electric vehicle.

The control device, the battery module, and the electric vehicle according to the present invention have the following configurations.
(1): A control device according to an aspect of the present invention includes an acquisition unit that acquires a measured value of load or strain at a plurality of positions on a predetermined surface of a casing of a secondary battery, and each of the plurality of positions. And a control unit that controls charging and discharging of the secondary battery based on a change in the load or the strain with respect to the charging rate of the secondary battery.

(2): In the aspect of (1) above, the measured values of the load or the strain at the plurality of positions are measured by a pressure distribution sensor arranged in contact with the casing of the secondary battery. Is.

(3): In the aspect of (2) above, a calculation unit that calculates the amount of change in the load or the strain with respect to the charging rate is further provided for each detection element of the pressure distribution sensor.

(4): In the aspect of the above (2), the load or the strain is integrated for each set including a plurality of detection elements of the pressure distribution sensor, and a change amount of the load or the strain with respect to the charging rate is calculated. It further comprises a calculating unit for calculating.

(5): In the aspects of (1) to (4), the change in the load or the strain is a difference of the load or the strain for each amount of electricity, or a difference of the load or the strain for each charging rate. There is something.

(6): In the above aspects (1) to (5), the control unit controls at least one of current, voltage, and electric power during charging/discharging of the secondary battery.

(7): In the above aspects (1) to (6), a determination unit that determines the state of the secondary battery based on the change in the load or the strain is further provided.

(8): In the above aspect (7), the determination unit determines the state of the secondary battery based on a difference in increasing tendency of the change in the load or the strain.

(9): In the above aspects (1) to (8), the secondary battery is a lithium ion battery.

(10): In the above aspects (1) to (9), in the case where the secondary battery is an assembled battery, the acquisition unit is a cell having the highest temperature among a plurality of cells included in the assembled battery. The measurement value of the load or the strain is acquired.

(11): A battery module according to an aspect of the present invention includes a secondary battery, a pressure sensor arranged in contact with a casing of the secondary battery, and a control device for controlling charging/discharging of the secondary battery. And an acquisition unit that acquires measured values of load or strain at a plurality of positions on a predetermined surface of the casing of the secondary battery measured by the pressure sensor, and And a control unit that controls charging and discharging of the secondary battery based on a change in the load or the strain with respect to the charging rate of the secondary battery at each position.

(12): An electric vehicle according to an aspect of the present invention includes the battery module according to (11) above.

According to (1) to (12), it is possible to determine the local state of the electrode and perform charge/discharge control suitable for the determined state. In addition, by controlling the current, voltage, and power based on the determined state by the above charge/discharge control, it is possible to perform control according to the local deterioration state of the secondary battery. Further, battery control based on the distribution (maximum/minimum SOC, maximum/minimum negative electrode deterioration rate) within the electrode surface of the wound body or the laminated body becomes possible.

It is a figure which shows an example of a structure of the charging/discharging control system S of 1st Embodiment. It is a figure which shows an example of a structure of the surface pressure distribution sensor 3 of 1st Embodiment. It is a graph which shows the relationship between the interlayer distance of the graphite used as the negative electrode material of 1st Embodiment, and SOC. FIG. 5 is a graph showing a relationship between strain ε and SOC in the negative electrode of the first embodiment and a graph showing a relationship between strain electric quantity difference dε/dQ and SOC. FIG. 5 is a diagram showing a graph showing a relationship between a load F and SOC in the negative electrode of the first embodiment and a graph showing a relationship between an electric quantity difference dF/dQ of the load F and SOC. It is a graph which compared the amount of change of the strain ε of the non-aqueous secondary battery in the reference state and the non-aqueous secondary battery in the battery capacity deterioration state of the first embodiment. It is a graph which compared the amount of change of the load F of the non-aqueous secondary battery of the reference state of the first embodiment and the non-aqueous secondary battery of the battery capacity deterioration state. It is a graph which compared the amount of change of the strain ε of the non-aqueous secondary battery in the reference state and the non-aqueous secondary battery in the stage shift state of the first embodiment. It is a graph which compared the amount of change of the load F of the non-aqueous secondary battery of the standard state and the non-aqueous secondary battery of the stage shift state of the first embodiment. It is a flow chart which shows an example of processing by ECU1 of a 1st embodiment. It is a figure explaining the setting value of discharge permission electric power of 1st Embodiment. It is a flow chart which shows an example of processing by ECU1 of a 2nd embodiment. It is a figure which shows the relationship between SOC calculated for every cluster of 2nd Embodiment, and the amount of change of the load F.

Hereinafter, embodiments of a control device, a battery module, and an electric vehicle of the present invention will be described with reference to the drawings. The control device of the present invention is installed in, for example, an electric vehicle and controls a non-aqueous secondary battery of the electric vehicle. The invention is not limited to this, and the control device of the present invention may be mounted on various devices powered by a non-aqueous secondary battery.

<First Embodiment>
FIG. 1 is a diagram showing an example of the configuration of the charge/discharge control system S of the first embodiment. The charge/discharge control system S includes, for example, an ECU (Electronic Control Unit) 1 (control device), a non-aqueous secondary battery 2 (an example of a secondary battery), a surface pressure distribution sensor 3 (an example of a pressure distribution sensor). The housing bind bar 4, the current sensor 5, the voltage sensor 6, and the output unit 7 are provided.

The non-aqueous secondary battery 2 is, for example, a lithium ion battery having a positive electrode and a negative electrode. The non-aqueous secondary battery 2 is a prismatic type, a laminated type, a round type, or the like. Each of the positive electrode and the negative electrode of the non-aqueous secondary battery 2 is connected to the ECU 1 via an electric wire.

The surface pressure distribution sensor 3 is arranged in contact with one surface of the casing of the non-aqueous secondary battery 2. The surface pressure distribution sensor 3 measures the surface pressure distribution on the contact surface with the non-aqueous secondary battery 2. FIG. 2 is a diagram showing an example of the configuration of the surface pressure distribution sensor 3 of the first embodiment. As shown in FIG. 2, the surface pressure distribution sensor 3 includes a plurality of pressure sensor elements 30 (hereinafter, also referred to as “pixels”) (an example of detection elements). Each of the plurality of pressure sensor elements 30 detects the pressure acting on each element, that is, the load per area. The surface pressure distribution sensor 3 is arranged so that the detection surfaces of these pressure sensor elements 30 contact one surface of the casing of the non-aqueous secondary battery 2. The surface pressure distribution sensor 3 outputs the measurement value measured by each of the plurality of pressure sensor elements 30 to the ECU 1 via the input/output unit 32. For example, the surface pressure distribution sensor 3 is arranged in the battery case in the stacking method of the wound body or the stacked body of the prismatic lithium ion battery.

The housing bind bar 4 is fixed so that the surface to be detected of the non-aqueous secondary battery 2 and the detection surface of the pressure sensor element 30 of the surface pressure distribution sensor 3 are kept in contact with each other. The housing bind bar 4 includes, for example, a first base material 4a and a second base material 4b that are arranged to face each other. The first base material 4a and the second base material 4b are connected by connecting members 4c and 4d. The housing bind bar 4 is fixed by the connecting members 4c and 4d in a state where the non-aqueous secondary battery 2 and the surface pressure distribution sensor 3 are sandwiched between the first base material 4a and the second base material 4b. There is.

The current sensor 5 is connected to a power line that connects the non-aqueous secondary battery 2 and the drive unit side. The current sensor 5 detects a current value of electric power discharged by the non-aqueous secondary battery 2 and a current value of electric power charged in the non-aqueous secondary battery 2, and outputs it to the ECU 1.

The voltage sensor 6 is connected to an electric wire that connects the non-aqueous secondary battery 2 and the ECU 1. The voltage sensor 6 detects a voltage on an electric wire connected to each of the positive electrode and the negative electrode of the non-aqueous secondary battery 2 and outputs the voltage to the ECU 1.

The ECU 1 determines the state of the non-aqueous secondary battery 2 and controls the charging/discharging of the non-aqueous secondary battery 2 based on the determined state. Details of the configuration of the ECU 1 will be described later.

[Configuration of ECU 1]
The ECU 1 includes, for example, a control unit 10 and a storage unit 12. The control unit 10 includes, for example, an acquisition unit 20, a charge electricity amount calculation unit 21, an SOC calculation unit 22, a change amount calculation unit 23 (calculation unit), a state determination unit 24 (determination unit), and charge/discharge control. The unit 25 (control unit) and the notification unit 26 are provided. The components of the control unit 10 are realized, for example, by a computer processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of the components of the control unit 10 are hardware such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit). It may be realized by (including a circuit portion), or may be realized by cooperation of software and hardware. The program may be stored in the storage unit 12 in advance, or may be stored in a removable storage medium such as a DVD or a CD-ROM, and installed in the storage unit 12 by mounting the storage medium in the drive device. May be done.

The acquisition unit 20 acquires the pressure value measured by each of the plurality of pressure sensor elements 30 of the surface pressure distribution sensor 3, the current value measured by the current sensor 5, the voltage value measured by the voltage sensor 6, and the like. .. The acquisition unit 20 stores the pressure value acquired from the surface pressure distribution sensor 3 in the storage unit 12 as the surface pressure distribution information 12A in association with the time information. In addition, the acquisition unit 20 associates the acquired current value and voltage value with the time information and stores the current value and the voltage value in the storage unit 12 as the current-voltage information 12B.

The charged electricity amount calculation unit 21 calculates the amount of charging power charged in the non-aqueous secondary battery 2 based on the current value and the voltage value acquired by the acquisition unit 20. The charged electricity amount calculation unit 21 associates the calculated amount of charged electricity with the time information at the time of charging and stores it in the storage unit 12 as the charged electricity amount information 12C. The charge electricity amount calculation unit 21 may calculate the discharge power amount discharged from the non-aqueous secondary battery 2 based on the current value and the voltage value acquired by the acquisition unit 20.

The SOC calculation unit 22 calculates the SOC (charge rate) of the non-aqueous secondary battery 2 based on, for example, current integration, the RLS method, or the like. For example, the SOC calculation unit 22 determines the SOC of the non-aqueous secondary battery based on the capacity of the non-aqueous secondary battery 2, the initial SOC, and the current value of the electric power charged and discharged in the non-aqueous secondary battery 2. calculate. The capacity of the non-aqueous secondary battery 2 is the amount of electricity (current×time) that the non-aqueous secondary battery 2 discharges from the certain charged state of the non-aqueous secondary battery 2 until it reaches the discharge end voltage. Ah]. The initial SOC is the SOC in the initial state of the non-aqueous secondary battery 2. The current value of the electric power charged and discharged in the non-aqueous secondary battery 2 is the detection value detected by the current sensor 5.

The change amount calculation unit 23 calculates characteristic information that can be used to determine the state of the non-aqueous secondary battery 2. It is generally known that the positive electrode and the negative electrode of the non-aqueous secondary battery 2 are expanded by charging. Further, for example, the expansion coefficient of graphite used for the negative electrode is larger than that of the positive electrode. Therefore, the expansion of the non-aqueous secondary battery 2 due to charging is considered to be caused by the negative electrode.

FIG. 3 is a graph showing the relationship between the interlayer distance of graphite used as the negative electrode material and SOC. As shown in FIG. 3, as the SOC increases, that is, as Li is introduced into the structure of graphite, the interlayer distance of graphite increases. Here, the interlayer distance of graphite does not increase linearly as SOC (corresponding to x in Li _x C ₆ ) increases, but shows discontinuous increase behavior according to the stage structure. In the example shown in FIG. 3, there are three stages (stages 1 to 3) in which the increasing tendency of the interlayer distance is different, that is, the inclinations of the interlayer distance with respect to the SOC are different from each other. By monitoring the expansion of the non-aqueous secondary battery 2 caused by the expansion of the negative electrode during charging, or the change in the load applied to and detected by the surface pressure distribution sensor 3 in response to the expansion, the negative electrode The state (stage) can be estimated.

Therefore, when the non-aqueous secondary battery 2 is charged, the change amount calculation unit 23 uses the pressure value of the surface pressure distribution sensor 3 acquired by the acquisition unit 20 to expand (strain) the negative electrode of the non-aqueous secondary battery 2. ) Is calculated, and the calculated electric quantity difference dε/dQ of the strain is calculated. FIG. 4 is a graph showing a relationship between the strain ε and the SOC in the negative electrode and a graph showing a relationship between the strain difference electric quantity difference dε/dQ and the SOC. The example shown in FIG. 4 corresponds to the case where the increasing tendency of the interlayer distance with respect to the SOC as shown in FIG. 3 includes three stages. As shown in FIG. 4, as the SOC increases, the strain ε in the negative electrode exhibits a discontinuous increase behavior according to the three-stage structure. By calculating the electrical quantity difference dε/dQ of the strain ε that exhibits discontinuous increase behavior according to these three stage structures, it is possible to obtain values associated with each of the three stage structures. By calculating such an electric amount difference dε/dQ, it is possible to discriminate between a region in which the amount of change in strain is large and a region in which the amount of strain is small, and it is possible to estimate the inside of the negative electrode.

Further, assuming that the elastic constant E of the non-aqueous secondary battery 2 is constant, the change amount calculation unit 23 determines that the stress σ (=load F/area S) is proportional to the strain ε, and thus the strain as shown in FIG. By replacing the relationship between ε and SOC with the relationship between the load F and SOC, it becomes possible to estimate the state of the negative electrode from the difference in electric quantity dF/dQ of the load F. FIG. 5 is a diagram showing a graph showing the relationship between the load F and the SOC at the negative electrode, and a graph showing the relationship between the electric quantity difference dF/dQ of the load F and the SOC. As shown in FIG. 5, as the SOC increases, the load F on the negative electrode exhibits a discontinuous increase behavior according to the three-stage structure. When the electric quantity difference dF/dQ of the load F that exhibits discontinuous increase behavior corresponding to these three stage structures is calculated, it is possible to obtain values associated with each of the three stage structures. By calculating such an electric amount difference dF/dQ, it is possible to distinguish between a region in which the amount of change in the load F is large and a region in which the amount of change in the load F is small, and it is possible to estimate the state of the negative electrode.

The change amount calculation unit 23 may calculate an index value indicating the state of charge such as dε/dSOC or dF/dSOC, which is the change amount with respect to the difference between the SOC of the strain ε or the load F.

The state determination unit 24 determines the state of the non-aqueous secondary battery 2 based on the change amount of the strain ε or the change amount of the load F calculated by the change amount calculation unit 23. For example, the state determination unit 24 determines the capacity deterioration state, the stage shift state, etc. of the non-aqueous secondary battery 2.

(Determining the capacity deterioration state)
The capacity of the non-aqueous secondary battery decreases due to deterioration over time. The state determination unit 24 determines such a capacity decrease of the non-aqueous secondary battery. FIG. 6 is a graph comparing the amount of change in strain ε of the non-aqueous secondary battery in the reference state and the non-aqueous secondary battery in the state of deteriorated battery capacity. The reference state is a state in which it is assumed that the soundness of the non-aqueous secondary battery is maintained (not deteriorated). The reference state includes, for example, an initial state before using the non-aqueous secondary battery. Further, the amount of change in strain or load in the reference state may be an average value of strain or load based on measured values of a plurality of pixels. In FIG. 6, in order to make it easier to see the difference in behavior between the graph of the non-aqueous secondary battery in the reference state and the graph of the non-aqueous secondary battery in the deteriorated capacity, a graph of the non-aqueous secondary battery in the deteriorated capacity is shown. The vertical axis (distortion) of is offset. In FIG. 6, the states of the negative electrode of the non-aqueous secondary battery in the standard state are shown by stages 1 to 3, and the states of the negative electrode of the non-aqueous secondary battery in the state of capacity deterioration are shown by stages 1A to 3A. When the capacity of the negative electrode decreases, the amount of change in the charging depth of the negative electrode increases for the same SOC. Therefore, as shown in FIG. 6, as compared with the stage 2 of the non-aqueous secondary battery in the standard state, the SOCstg2A[Ah], which is the width of the stage 2A of the non-aqueous secondary battery in the deteriorated capacity, is equal to the stage 1A. On the side of the switching point between and and on the side of the switching point between stage 3A, the distance becomes narrower by ΔSOC1, ΔSOC2 or ΔQ1, ΔQ2, respectively. That is, SOCstg2A[Ah], which is the width of the stage 2A, is narrowed by ΔSOC1+ΔSOC2 (or ΔQ1+ΔQ2). Conventionally, simply measuring strain or load cannot be used for estimation of the above-mentioned stage because the absolute value thereof varies depending on the deterioration state, temperature, and the like. On the other hand, the state determination unit 24 of the present embodiment can detect the decrease in the capacity of the negative electrode based on the above tendency.

FIG. 7 is a graph comparing the amount of change in the load F of the non-aqueous secondary battery in the reference state and the non-aqueous secondary battery in the state of deteriorated battery capacity. In FIG. 7, in order to make it easier to see the difference in behavior between the graph of the non-aqueous secondary battery in the reference state and the graph of the non-aqueous secondary battery in the deteriorated capacity, a graph of the non-aqueous secondary battery in the deteriorated capacity is shown. The vertical axis (load) of is offset. In FIG. 7, the stages of the non-aqueous secondary battery in the standard state are shown by stages 1 to 3, and the stages of the non-aqueous secondary battery in the capacity deteriorated state are shown by stages 1A to 3A. When the capacity of the negative electrode deteriorates, the amount of change in the charging depth of the negative electrode increases for the same SOC. Therefore, as shown in FIG. 7, the SOCstg2A[Ah], which is the width of the stage 2A of the non-aqueous secondary battery in the capacity deteriorated state, is smaller than that of the stage 1A of the non-aqueous secondary battery in the standard state, as shown in FIG. On the side of the switching point between and, and on the side of the switching point between stage 3A, ΔSOC1 and ΔSOC2 or ΔQ1 and ΔQ2, respectively. That is, SOCstg2A[Ah], which is the width of the stage 2A, is narrowed by ΔSOC1+ΔSOC2 (or ΔQ1+ΔQ2). The state determination unit 24 can detect the decrease in the capacity of the negative electrode based on this tendency.

For example, the state determination unit 24 detects the width of the stage 2 by detecting the SOC of the switching point between the stage 1 (1A) and the stage 2 (2A), the stage 2 (2A), and the stage 3 (3A). ) And the SOC of the switching point.

(Determination of stage misalignment)
In the non-aqueous secondary battery, a shift in the SOC-stage relationship (hereinafter, also referred to as “stage shift”) may occur due to a shift in the N/P ratio or the like. The state determination unit 24 determines such a stage shift of the non-aqueous secondary battery. FIG. 8 is a graph comparing the amounts of change in strain ε of the non-aqueous secondary battery in the reference state and the non-aqueous secondary battery in the displaced state. In FIG. 8, in order to make it easier to see the difference in behavior between the graph of the non-aqueous secondary battery in the standard state and the graph of the non-aqueous secondary battery in the stage shifted state, a graph of the non-aqueous secondary battery in the stage shifted state is shown. The vertical axis (strain) of is offset. In FIG. 8, the stages of the non-aqueous secondary battery in the reference state are shown by stages 1 to 3, and the stages of the non-aqueous secondary battery in the stage shift state are shown by stages 1B to 3B. As shown in FIG. 8, as compared with the non-aqueous secondary battery in the standard state, the position of the non-aqueous secondary battery in the stage shift state is changed (the position changed from the stage 3B to the stage 2B, the stage 2B to the stage). The position (change to 1B) is shifted by ΔSOC%. The state determination unit 24 can detect the stage shift based on the presence or absence of the shift.

FIG. 9 is a graph comparing the amount of change in the load F of the non-aqueous secondary battery in the standard state and the non-aqueous secondary battery in the stage-shifted state. In FIG. 9, in order to make it easier to see the difference in behavior between the graph of the non-aqueous secondary battery in the standard state and the graph of the non-aqueous secondary battery in the displaced state, a graph of the non-aqueous secondary battery in the displaced state is shown. The vertical axis (load) of is offset. In FIG. 9, the stages of the non-aqueous secondary battery in the standard state are shown by stages 1 to 3, and the stages of the non-aqueous secondary battery in the stage shift state are shown by stages 1B to 3B. As shown in FIG. 9, as compared with the non-aqueous secondary battery in the standard state, the position of the stage of the non-aqueous secondary battery in the stage shift state changes (the position changing from the stage 3B to the stage 2B, the stage 2B to the stage). The position (change to 1B) is shifted by ΔSOC%. The state determination unit 24 can detect the stage shift based on the presence or absence of the shift.

For example, in order to detect the presence or absence of the above deviation, the state determination unit 24 determines the SOC of the switching point between the stage 1 (1B) and the stage 2 (2B), the stage 2 (2B) and the stage 3 (3B). SOC of the switching point of is determined.

The charge/discharge control unit 25 controls charging/discharging of the non-aqueous secondary battery 2 based on the state of the non-aqueous secondary battery determined by the state determination unit 24. For example, the charge/discharge control unit 25, in the charge control, the charge permission power that is the upper limit value of the usable power, the charge permission voltage that is the upper limit value of the usable voltage, and the charge permission that is the upper limit value of the usable current. The SOC reference value used for setting the current is changed based on the above-mentioned ΔSOC%. In addition, for example, the charge/discharge control unit 25, in the discharge control, the discharge permission power that is the upper limit value of the usable power, the discharge permission voltage that is the upper limit value of the usable voltage, and the upper limit value of the usable current. The SOC reference value used for setting the discharge permission current is changed based on the above-mentioned ΔSOC%.

The notification unit 26 controls the output unit 7 to notify the determination result of the state determination unit 24 and the information regarding the change of the control content of the charge/discharge control unit 25. The output unit 7 is, for example, a display or a speaker installed in the vehicle. For example, the notification unit 26 causes the display to display a message or an image notifying that the capacity of the non-aqueous secondary battery 2 has deteriorated or that the condition (SOC reference value) in charge/discharge control has been changed. .. In addition, the notification unit 26 outputs a message, an error sound, or the like from the speaker to notify that the capacity of the non-aqueous secondary battery 2 has deteriorated or that the condition (reference value of SOC) in charge/discharge control has been changed. You may output it.

The storage unit 12 is realized by, for example, an HDD (Hard Disc Drive), a flash memory, an EEPROM (Electrically Erasable Programmable Read Only Memory), a ROM (Read Only Memory), a RAM (Random Access Memory), or the like.

(Processing of ECU 1)
FIG. 10 is a flowchart showing an example of processing by the ECU 1. First, the ignition of the electric vehicle equipped with the ECU 1 is turned on (step S101). Here, it is assumed that the charging process of the non-aqueous secondary battery 2 has already been performed, and the information on the surface pressure distribution, the current, and the voltage acquired at the time of charging is stored in the storage unit 12.

Next, the charged electricity amount calculation unit 21 calculates the charged electricity amount based on the current-voltage information 12B stored in the storage unit 12 (step S103). Here, the charged electricity amount calculation unit 21 calculates the change with time of the charged electricity amount by integrating the charged electricity amount during charging.

Next, the change amount calculation unit 23 calculates the strain or load of the non-aqueous secondary battery 2 for each pressure sensor element 30 (for each pixel) based on the surface pressure distribution information 12A stored in the storage unit 12. Yes (step S105). Next, the change amount calculation unit 23 calculates the change amount of the strain or load for each pixel based on the calculated strain or load and the charged electricity amount calculated by the charged electricity amount calculation unit 21 (S107). ). The amount of change in strain or load is, for example, the difference in electric amount dε/dQ of the strain ε or the difference in electric amount dF/dQ of the load F.

Next, the SOC calculation unit 22 calculates the SOC of the non-aqueous secondary battery 2 based on the current/voltage information 12B stored in the storage unit 12 (step S109). Here, the SOC calculation unit 22 calculates the change with time of SOC during charging. Next, the state determination unit 24 determines the state of the non-aqueous secondary battery 2 based on the strain or load change amount calculated by the change amount calculation unit 23 and the SOC calculated by the SOC calculation unit 22. Yes (step S111). For example, the state determination unit 24 generates a graph showing the relationship between the SOC and the amount of change in strain or load for each pixel, and determines the SOC at the switching point of the stage. For example, the state determination unit 24 determines the SOC at the switching point from stage 1 to stage 2 as shown in FIG. Then, the state determination unit 24 calculates the average value of the SOC of the stage switching points determined for each pixel (hereinafter, referred to as “average stage switching point”). Then, the state determination unit 24 calculates the maximum value ΔSOC _max of the difference between the calculated average stage switching point and the switching point of each pixel based on the following equation (1), for example.

ΔSOC _max =max(|stage 1 switching point SOC of each pixel−average stage switching point SOC|) Equation (1)

Next, the state determination unit 24 determines whether or not the calculated ΔSOC _max is greater than or equal to a preset threshold value (step S113). When the state determination unit 24 determines that ΔSOC _max is not equal to or more than the threshold value, the charged electricity amount calculation unit 21 calculates the charged electricity amount during another charging (step S103) and repeats the subsequent processing.

When the state determination unit 24 determines that ΔSOC _max is greater than or equal to the threshold value, the charge/discharge control unit 25 determines the non-aqueous secondary battery 2 based on the state of the non-aqueous secondary battery determined by the state determination unit 24. The charging/discharging is controlled (step S115). For example, the charge/discharge control unit 25 updates the SOC reference value SOC used for setting the charge permitted power, the charge permitted voltage, and the charge permitted current in the charge control to “SOC+ΔSOC _max ”. Further, the charge/discharge control unit 25 updates the SOC reference value SOC used for setting the discharge permitting power, the discharge permitting voltage, and the discharge permitting current in the discharge control to “SOC−ΔSOC _max ”.

FIG. 11 is a diagram for explaining the set value of the discharge permission power. As shown in FIG. 11, conventionally, even when the above-described local SOC stage deviation occurs, it is not taken into consideration, and the average value SOC _ave of the SOC is used as the reference value of the discharge permission power. Was adopted. On the other hand, in the present embodiment, in consideration of the local SOC calculated from the amount of change in the load F, etc., and in consideration of the electrode surface region whose SOC is lower than the average, “SOC _P − lower than the average value SOC _ave ” is considered. ΔSOC _max ” is adopted as the reference value of the discharge permitted power. This enables charge/discharge control in consideration of local SOC.

Next, the notification unit 26 controls the output unit 7 to, for example, change the settings of the charging permission power, the charging permission voltage, and the charging permission current in the charging control, and the discharging permission power in the discharging control. , The discharge permission voltage and the discharge permission current have been changed (step S117). With the above, the processing of this flowchart is completed.

According to the first embodiment described above, it is possible to determine the local state of the electrode and perform charge/discharge control suitable for the determined state.

<Second Embodiment>
The second embodiment will be described below. Compared to the first embodiment, the ECU 1 of the second embodiment calculates strain or load of the non-aqueous secondary battery 2 for each of the plurality of pressure sensor elements 30 of the surface pressure distribution sensor 3 (for each pixel). The difference is that a plurality of pixels are collectively processed as a cluster. Therefore, for the configuration and the like, the drawings described in the first embodiment and the related description are used, and the detailed description is omitted.

(Processing of ECU 1)
FIG. 12 is a flowchart showing an example of processing by the ECU 1. First, the ignition of the electric vehicle equipped with the ECU 1 is turned on (step S201). Here, it is assumed that the charging process of the non-aqueous secondary battery 2 has already been performed, and the information on the surface pressure distribution, the current, and the voltage acquired at the time of charging is stored in the storage unit 12.

Next, the charged electricity amount calculation unit 21 calculates the charged electricity amount based on the current-voltage information 12B stored in the storage unit 12 (step S203). Here, the charged electricity amount calculation unit 21 calculates the change with time of the charged electricity amount by integrating the charged electricity amount during charging.

Next, the change amount calculation unit 23 clusters a plurality of pixels of the surface pressure distribution sensor 3 based on the surface pressure distribution information 12A stored in the storage unit 12, and the clusters of the non-aqueous secondary battery 2 are clustered. The strain or load is calculated (step S205). Next, the change amount calculation unit 23 calculates the change amount of the strain or load for each cluster based on the calculated strain or load and the charged electricity amount calculated by the charged electricity amount calculation unit 21 (S207). ). The amount of change in strain or load is, for example, the difference in electric amount dε/dQ of the strain ε or the difference in electric amount dF/dQ of the load F.

Next, the SOC calculation unit 22 calculates the SOC of the non-aqueous secondary battery 2 based on the current/voltage information 12B stored in the storage unit 12 (step S209). Here, the SOC calculation unit 22 calculates the change with time of SOC during charging. Next, the state determination unit 24 determines the state of the non-aqueous secondary battery 2 based on the strain or load change amount calculated by the change amount calculation unit 23 and the SOC calculated by the SOC calculation unit 22. Yes (step S211). For example, the state determination unit 24 generates a graph showing the relationship between the SOC and the amount of change in strain or load for each cluster, and determines the SOC at the stage switching point. Then, the state determination unit 24 calculates the average value of the SOC of the switching points of the stages determined for each cluster (hereinafter, referred to as “average stage switching point”). Next, the state determination unit 24 calculates the maximum value ΔSOC _max of the difference between the calculated average stage switching point and the switching point of each pixel based on the following equation (1), for example.

ΔSOC _max =max(|stage 1 switching point SOC-average stage switching point SOC| of each cluster) Equation (1)

Next, the state determination unit 24 determines whether or not the calculated ΔSOC _max is greater than or equal to a preset threshold value (step S213). When the state determination unit 24 determines that ΔSOC _max is not equal to or more than the threshold value, the charged electricity amount calculation unit 21 calculates the charged electricity amount during another charging (step S203) and repeats the subsequent processing.

When the state determination unit 24 determines that ΔSOC _max is greater than or equal to the threshold value, the charge/discharge control unit 25 determines the non-aqueous secondary battery 2 based on the state of the non-aqueous secondary battery determined by the state determination unit 24. The charging/discharging is controlled (step S215). For example, the charge/discharge control unit 25 updates the SOC reference value SOC used for setting the charge permitted power, the charge permitted voltage, and the charge permitted current in the charge control to “SOC+ΔSOC _max ”. Further, the charge/discharge control unit 25 updates the SOC reference value SOC used for setting the discharge permitting power, the discharge permitting voltage, and the discharge permitting current in the discharge control to “SOC−ΔSOC _max ”.

Next, the notification unit 26 controls the output unit 7 to, for example, change the settings of the charging permission power, the charging permission voltage, and the charging permission current in the charging control, and the discharging permission power in the discharging control. , The discharge permission voltage and the discharge permission current have been changed (step S217). With the above, the processing of this flowchart is completed.

FIG. 13 is a diagram showing the relationship between the SOC calculated for each cluster and the amount of change in the load F. FIG. 13 shows an example in which a plurality of pixels in the surface pressure distribution sensor 3 are collected for each row and integrated. As shown in FIG. 13, as compared with the width D1 of the stage 2 in the initial stage of the non-aqueous secondary battery 2, the stage 2 is provided on the can bottom side and the can lid side of the negative electrode after the non-aqueous secondary battery 2 has been used for a predetermined cycle. Areas (widths D1a and D1b) in which the width of the area is reduced can be confirmed. Due to the decrease in the width of the stage 2, it can be estimated that the negative electrode deterioration has progressed after the use of the predetermined cycle.

According to the second embodiment described above, it is possible to determine the local state of the electrode and perform charge/discharge control suitable for the determined state.

The ECU 1 may perform both the process for each pixel of the surface pressure distribution sensor 3 and the process for each cluster. When the non-aqueous secondary battery 2 is an assembled battery, a temperature sensor is installed in each of a plurality of cells included in the assembled battery to measure the temperature, and the surface pressure distribution of the cell having the highest measured temperature is measured. You may make it acquire and process a measured value. The ECU 1 is also applicable to a lithium ion secondary battery in which not only graphite but also a silicon-based material is added to graphite in the negative electrode.

As described above, the embodiments for carrying out the present invention have been described by using the embodiments, but the present invention is not limited to such embodiments, and various modifications and substitutions are made without departing from the gist of the present invention. Can be added.

DESCRIPTION OF SYMBOLS 1... ECU, 2... Non-aqueous secondary battery, 3... Surface pressure distribution sensor, 4... Housing bind bar, 5... Current sensor, 6... Voltage sensor, 7... Output part, 10... Control part, 12... Storage part , 20... Acquisition unit, 21... Charging electricity amount calculation unit, 22... SOC calculation unit, 23... Change amount calculation unit, 24... State determination unit, 25... Charge/discharge control unit, 26... Notification unit

Claims (12)

An acquisition unit that acquires a measured value of load or strain at a plurality of positions on a predetermined surface of the housing of the secondary battery,
In each of the plurality of positions, based on the change of the load or the strain with respect to the charging rate of the secondary battery, a control unit that controls the charging and discharging of the secondary battery,
A control device including. The measured values of the load or the strain at the plurality of positions are measured by a pressure distribution sensor arranged in contact with the casing of the secondary battery,
The control device according to claim 1. For each detection element of the pressure distribution sensor, further comprising a calculation unit that calculates a change amount of the load or the strain with respect to the charging rate,
The control device according to claim 2. For each set including a plurality of detection elements of the pressure distribution sensor, the load or the strain is integrated, further comprising a calculation unit for calculating a change amount of the load or the strain with respect to the charging rate,
The control device according to claim 2. The change in the load or the strain is a difference for each electric quantity of the load or the strain, or a difference for each charge rate of the load or the strain,
The control device according to any one of claims 1 to 4. The control unit controls at least one of current, voltage, and power in charging/discharging the secondary battery,
The control device according to any one of claims 1 to 5. Further comprising a determination unit that determines the state of the secondary battery based on the change in the load or the strain,
The control device according to any one of claims 1 to 6. The determination unit determines the state of the secondary battery based on the difference in the increasing tendency of the change in the load or the strain,
The control device according to claim 7. The secondary battery is a lithium-ion battery,
The control device according to any one of claims 1 to 8. The acquisition unit, when the secondary battery is an assembled battery, among the plurality of cells included in the assembled battery, acquires the measured value of the load or the strain in the cell having the highest temperature,
The control device according to any one of claims 1 to 9. A secondary battery,
A pressure sensor arranged in contact with the housing of the secondary battery,
A control device for controlling charge/discharge of the secondary battery,
Equipped with
The control device is
An acquisition unit that acquires measured values of load or strain at a plurality of positions on a predetermined surface of the casing of the secondary battery, which are measured by the pressure sensor,
In each of the plurality of positions, based on the change of the load or the strain with respect to the charging rate of the secondary battery, a control unit that controls the charging and discharging of the secondary battery,
With
Battery module. An electric vehicle comprising the battery module according to claim 11.