Secondary battery control device

Abstract

Provided is a control device for a secondary battery that suppresses deterioration in performance of the secondary battery due to peeling of a negative electrode active material. A control device (1) for a secondary battery (9) is provided with an SOC sensor (121) and a controller (100). The controller (100) determines whether or not the SOC in at least one of the plurality of battery modules (90) is equal to or greater than a predetermined first reference value, and if the SOC is equal to or greater than the first reference value, executes a first control for sequentially connecting each of the plurality of battery modules (90) to the motor (31) and sequentially discharging the plurality of battery modules (90) until the SOC of each of the battery modules (90) decreases to the first reference value.

Description

Technical Field

[0001] The present invention relates to a control device for a secondary battery. Background Art

[0002] For example, Patent Document 1 discloses a Si-containing negative electrode active material for lithium-ion batteries. This negative electrode active material comprises Si-containing granules formed by combining a Si alloy or pure Si with a fine-particle carbon material. According to Patent Document 1, the use of Si in the negative electrode can increase the discharge capacity of the lithium-ion battery.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-134205

[0006] Technical problem to be solved by the invention

[0007] However, the negative electrode active material disclosed in Patent Document 1 may peel off from the current collector due to repeated expansion and contraction during charge and discharge. If the negative electrode active material peels off, the negative electrode loses its function and malfunctions. Summary of the Invention

[0008] The present invention has been made in view of this point, and an object of the present invention is to suppress the performance degradation of a secondary battery caused by the peeling of a negative electrode active material.

[0009] Technical means for solving technical problems

[0010] A first embodiment of the present invention relates to a control device for a secondary battery, comprising a plurality of battery assemblies, each of which is composed of one or more battery cells and is connected to a driving source of a vehicle, and power is supplied from the plurality of battery assemblies to the driving source, wherein the one or more battery cells each have a negative electrode containing a negative electrode active material.

[0011] According to the first method, the control device includes: a state sensor, which detects a parameter representing the SOC of each of the multiple battery assemblies; and a controller, which switches the electrical connection between the multiple battery assemblies and the drive source based on the detection signal of the state sensor, and the controller determines whether the SOC in at least one of the multiple battery assemblies is above a specified first reference value based on the detection signal of the SOC sensor. When the SOC is above the first reference value, the controller executes a first control, which connects the multiple battery assemblies to the drive source in turn, and discharges the multiple battery assemblies in turn until the respective SOCs are reduced to the first reference value.

[0012] Here, the term "parameter representing the SOC" is used in a broad sense. The parameter may be the SOC itself, or a parameter that changes according to the increase or decrease of the SOC, such as the current charge amount of the secondary battery. For the parameter compared with the first reference value, other parameters such as the current charge amount may be used instead of the SOC. That is, "the case where the SOC is greater than the first reference value" may be a case where the SOC is directly compared with the first reference value, or a case where the SOC is indirectly compared with the first reference value, such as when the parameter representing the SOC is compared with the first reference value.

[0013] According to the first embodiment described above, the controller executes the first control when the SOC is above the first reference value. By executing the first control, the number of battery cells involved in charging and discharging can be minimized compared to when multiple battery modules are connected in parallel. This reduces the frequency of collisions and contractions between battery cells caused by intercalation reactions, thereby suppressing performance degradation of the secondary battery due to the exfoliation of negative electrode active material.

[0014] Furthermore, when the SOC is less than the first reference value, and the depth of discharge of each battery cell is deep, there is a concern that the C-rate becomes high, leading to performance degradation from a different perspective than peeling. Therefore, the controller, taking this concern into account, does not execute the first control. This is particularly advantageous in suppressing performance degradation of the secondary battery.

[0015] In addition, according to the second embodiment of the present invention, the controller may determine whether the SOC is less than the first reference value in all the multiple battery assemblies based on the detection signal of the status sensor. When the SOC is less than the first reference value, the controller performs a second control, which connects the multiple battery assemblies in parallel to the driving source and discharges the multiple battery assemblies simultaneously.

[0016] According to the second method, when the depth of discharge of each battery cell increases, multiple battery packs are connected in parallel relative to the drive source. This can suppress the C-rate observed on a battery pack basis, and further on a battery cell basis, and is beneficial in preventing performance degradation of the secondary battery. By switching the electrical connection based on the SOC, performance degradation of the secondary battery can be minimized.

[0017] Furthermore, according to a third aspect of the present invention, the controller may select a discharge mode from a plurality of discharge modes set corresponding to the electrical connection based on a setting input by an occupant of the vehicle, and the controller may select and execute one of the first control and the second control based on a detection signal of the state sensor to achieve the selected discharge mode, wherein the plurality of discharge modes include: a first mode in which the first control is continued regardless of the detection signal of the SOC sensor by allowing discharge within an SOC range having the first reference value as a lower limit; and a second mode in which the first control and the second control are separately used according to the detection signal of the SOC sensor by allowing discharge within an SOC range having a second reference value as a lower limit, the second reference value being set to be smaller than the first reference value.

[0018] According to the third embodiment, the drivable distance in the first mode is shorter than that in the second mode by an amount equal to the lower limit of the first reference value. The first mode suppresses secondary battery performance degradation better than the second mode by an amount equal to the lower limit of the first reference value. The first and second modes are not designed to balance drivable distance and extended secondary battery life, but rather prioritize one over the other. The occupant can drive the vehicle in either the first mode or the second mode.

[0019] By allowing the occupant to select the mode rather than being fixed to the first or second mode, flexible discharge control can be achieved according to the occupant's preferences, the occupant's situation, etc. This improves the usability of the vehicle.

[0020] In addition, according to a fourth embodiment of the present invention, after the drive source is started, the controller notifies the occupant of first information, the first information being composed of: a first distance indicating the distance that the vehicle can travel in the first mode, a second distance indicating the distance that the vehicle can travel in the second mode, a first degradation indicator indicating the degree of deterioration of the maximum capacity of the secondary battery when the first distance is completed, and a second degradation indicator indicating the degree of deterioration when the second distance is completed, and the controller accepts selection of the first mode or the second mode based on the setting input of the occupant.

[0021] According to the fourth aspect, by notifying the occupant of the first information as described above, the advantages of the first mode and the second mode can be quantitatively understood. This allows for flexible discharge control tailored to the occupant's preferences, circumstances, and other factors. This improves vehicle usability.

[0022] Furthermore, when only the first and second distances are displayed, it is easier to select the second mode, which allows for a longer travel distance. By simultaneously displaying the first and second degradation indicators, the occupant can quantitatively grasp the degree of secondary battery degradation. This increases the frequency of selecting the first mode, which is beneficial for preventing secondary battery performance degradation.

[0023] In addition, according to the fifth embodiment of the present invention, the controller may respectively estimate a first residual value indicator and a second residual value indicator based on the first degradation indicator and the second degradation indicator, the first residual value indicator representing the economic value of the secondary battery when the first distance is completed, and the second residual value indicator representing the economic value when the second distance is completed, and the first information is constructed to include both the first residual value indicator and the second residual value indicator.

[0024] According to the fifth aspect, by further notifying the first and second residual value indicators, the occupant can more appropriately grasp the degree of secondary battery degradation. This increases the frequency of selecting the first mode, which is beneficial for suppressing secondary battery performance degradation.

[0025] In addition, according to a sixth aspect of the present invention, it is also possible that, during the driving of the vehicle when the first mode is selected, the controller notifies the occupant of second information, the second information being composed of: an extension of the drivable distance when switching from the first mode to the second mode, and a third degradation indicator indicating the degree of deterioration of the maximum capacity of the secondary battery when the extension is completed, and the controller accepts the change from the first mode to the second mode based on the setting input of the occupant.

[0026] According to the sixth aspect, the controller accepts the change from the first mode to the second mode even while the vehicle is traveling. This allows for flexible discharge control in real time based on the occupant's situation, etc., thereby improving the usability of the vehicle.

[0027] Furthermore, simply accepting the change to the second mode makes it easier to select the second mode, which allows for a longer driving range. By notifying the occupant of the second information, including the third degradation indicator, the occupant can quantitatively grasp the degree of secondary battery degradation. This increases the frequency of the first mode, which is beneficial for suppressing secondary battery performance degradation.

[0028] In addition, according to the seventh embodiment of the present invention, when a specified value that is higher than the first reference value and lower than the fully charged state is set as an intermediate reference value, the controller determines whether the SOC of all the multiple battery assemblies is reduced to the intermediate reference value based on the detection signal of the SOC sensor, and when the SOC is reduced to the intermediate reference value, the controller executes notification of the second information.

[0029] According to the seventh aspect, the second information can be notified to the occupant at a more appropriate timing, thereby improving the usability of the vehicle.

[0030] Furthermore, according to an eighth aspect of the present invention, the negative electrode active material contains Si.

[0031] In recent years, it has been found that the above-mentioned peeling problem becomes more pronounced when Si-based active materials are used as the negative electrode active material. The structure of the first embodiment is particularly effective when an active material containing Si is used.

[0032] Effects of the Invention

[0033] As described above, according to the present invention, it is possible to suppress the performance degradation of the secondary battery due to the peeling of the negative electrode active material. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram illustrating a vehicle.

[0035] Figure 2 This is an exploded view illustrating the structure of a secondary battery mounted on a vehicle.

[0036] Figure 3A It is a perspective view illustrating the structure of a battery cell.

[0037] Figure 3B It is a cross-sectional view illustrating the structure of a battery cell.

[0038] Figure 4 This is a block diagram illustrating the configuration of a secondary battery control device.

[0039] Figure 5 This is a functional block diagram illustrating the configuration of a secondary battery control device.

[0040] Figure 6A It is a diagram for explaining the first control.

[0041] Figure 6B It is a diagram for explaining the first control.

[0042] Figure 6C It is a diagram for explaining the first control.

[0043] Figure 6D It is a diagram for explaining the second control.

[0044] Figure 7 It is a diagram for explaining the first mode and the second mode.

[0045] Figure 8 It is a diagram for explaining the first information.

[0046] Figure 9 It is a diagram for explaining the second information.

[0047] Figure 10A is a flowchart illustrating processing associated with selection of the first mode and the second mode.

[0048] Figure 10B is a flowchart illustrating processing associated with the second mode.

[0049] Figure 10C is a flowchart illustrating processing associated with the first mode.

[0050] Figure 11 FIG. 1 is a diagram illustrating a mode selection switch on a touch panel.

[0051] Explanation of symbols

[0052] 3. Drive source

[0053] 31 Motor

[0054] 9 Secondary batteries

[0055] 90 battery pack

[0056] 91 battery cells

[0057] 92b negative electrode active material

[0058] 100 controllers

[0059] 112 mode selector switch

[0060] 121SOC sensor (status sensor)

[0061] 130 Notification Department

[0062] 140 display device

[0063] 150 touch panel

[0064] I1 First Information

[0065] I11 First Distance

[0066] I12 second distance

[0067] I13 First degradation index

[0068] I14 Second degradation index

[0069] I15 first residual value indicator

[0070] I16 Second residual value indicator

[0071] I2 Second Information

[0072] I21 extension (extension distance)

[0073] I22 Third degradation index

[0074] V vehicle. DETAILED DESCRIPTION

[0075] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

[0076] <1. Overall Structure>

[0077] Figure 1 1 is a schematic diagram illustrating a vehicle V. Figure 2 1 and 2 are exploded views illustrating the structure of a secondary battery 9 mounted on a vehicle V. The vehicle V shown in each figure is equipped with a control device 1 for the secondary battery 9 according to the present embodiment. The vehicle V is an automobile that can travel using electric power.

[0078] Specifically, the vehicle V according to the present embodiment is a so-called electric vehicle (EV). The vehicle V may also be a hybrid vehicle such as a plug-in hybrid electric vehicle (PHEV) that uses electricity as a main energy source.

[0079] Hereinafter, the front-rear direction based on the vehicle body V is referred to as the "vehicle front-rear direction" or simply the "front-rear direction". Figure 1 and Figure 2 As shown in the example, the "front" here refers to the direction in which the vehicle V moves forward, and the "rear" here refers to the direction in which the vehicle V moves backward (see also the following description). Figure 2 ).

[0080] Likewise, the left-right direction based on the body of the vehicle V is referred to as the "vehicle width direction" or simply the "left-right direction". Figure 1 and Figure 2 As illustrated, the “right” here refers to the right side as viewed from the perspective of an occupant of the vehicle V, and the “left” refers to the left side as viewed from the perspective of the occupant.

[0081] Likewise, the up-down direction based on the body of the vehicle V is referred to as the "vehicle height direction" or simply the "up-down direction". Figure 2 As shown in the example, "upward" here refers to a direction viewed from the perspective of a passenger of the vehicle V, and is perpendicular to and away from the road surface of the vehicle V. On the other hand, "downward" here refers to a direction viewed from the perspective of a passenger of the vehicle V, and is perpendicular to and toward the road surface of the vehicle V.

[0082] The secondary battery 9 in this embodiment is configured as a battery system including a plurality of battery modules 90 connected to the driving source 3 of the vehicle V. Figure 1 and Figure 2 As shown, each of the plurality of battery modules 90 is composed of one or more (in this embodiment, a plurality of) battery cells 91. Furthermore, each of the one or more battery cells 91 has a negative electrode composed of an active material (negative electrode active material) 92b.

[0083] Furthermore, the control device 1 for the secondary battery 9 in this embodiment is a device that supplies electric power from the plurality of battery packs 90 to the drive source 3 of the vehicle V. This control device 1 can also be referred to as a control device / control system that supplies electric power to the drive source 3 of the vehicle V so that the drive source 3 generates the driving force for the vehicle V to travel.

[0084] Specifically, the vehicle V according to this embodiment includes a plurality of wheels 2 , a motor 31 constituting a drive source 3 , an inverter 5 , a converter 6 , a charging port 7 , a switching circuit 8 , a secondary battery 9 , and a controller 100 . These elements are mounted or arranged on the vehicle V.

[0085] The plurality of wheels 2 are composed of two front wheels 2F and two rear wheels 2R. That is, the vehicle V according to this embodiment is a four-wheeled vehicle. All or part of the plurality of wheels 2 are connected to a drive source 3 via a shaft or the like.

[0086] The driving source 3 is composed of a motor 31 capable of performing both a power running operation and a regenerative operation. The motor 31 is, for example, a permanent magnet synchronous motor driven by a three-phase alternating current.

[0087] During power running, the motor 31 rotates based on power supplied from the secondary battery 9. This rotation generates the driving force for the vehicle V. When the motor 31 rotates during power running, this rotation is transmitted via a shaft (not shown). The rotation transmitted via the shaft rotates at least some of the wheels 2, including the two front wheels 2F. The rotation of at least some of the wheels 2 causes the vehicle V to travel.

[0088] In addition to functioning as a drive source during power running, the motor 31 can also function as a generator during regenerative operation. The motor 31 is electrically connected to the secondary battery 9 via the inverter 5 and the converter 6. This connection is utilized in both power running and regenerative operation, as described in detail below.

[0089] During power running, converter 6 steps down the high-voltage DC power supplied from secondary battery 9 to DC power having a predetermined base voltage. Converter 6 inputs the stepped-down DC power into inverter 5. Inverter 5 converts the DC power supplied from secondary battery 9 via converter 6 into three-phase AC power with different phases. Inverter 5 supplies the converted AC power to motor 31. By supplying AC power to motor 31, motor 31 rotates as described above.

[0090] During regenerative operation, inverter 5 converts AC power generated by the rotation of motor 31 into DC power. Inverter 5 inputs the converted DC power to converter 6. Converter 6 boosts the DC power input from motor 31 via inverter 5. Converter 6 charges secondary battery 9 with the boosted DC power.

[0091] As described above, the secondary battery 9 includes a plurality of battery modules 90. Similarly, as described above, each battery module 90 is composed of one or more (in this embodiment, a plurality of) battery cells 91.

[0092] For example, the secondary battery 9 according to the present embodiment includes a first assembly 90A, a second assembly 90B, and a third assembly 90C as the battery modules 90 constituting the plurality of battery modules 90 .

[0093] Here, as Figure 1 As shown, the plurality of battery modules 90 according to this embodiment are arranged in the longitudinal direction. The dimension of each battery module 90 arranged in the longitudinal direction is, for example, three or more times the dimension in the vehicle height direction (short side direction).

[0094] In addition, the plurality of battery assemblies 90 are connected in parallel to, for example, one motor 31. Each of the plurality of battery assemblies 90 may be connected to the motor 31 individually via the converter 6.

[0095] Each battery pack 90 is connected to the charging port 7 via an onboard charger or the like. The charging port 7 can also be referred to as a charging port. A connector of a power supply device can be connected to the charging port 7. Through this connection, power can be supplied from the power supply device to the vehicle V via the charging port 7.

[0096] The switching circuit 8 is configured to operate in response to a control signal received from the controller 100 , thereby switching the electrical connection between the plurality of battery assemblies 90 and the motor 31 .

[0097] Specifically, the switching circuit 8 can individually switch the electrical connection between each of the plurality of battery packs 90 and the motor 31. More specifically, the switching circuit 8 electrically connects (relays, energizes) or disconnects (disconnects) each of the plurality of battery packs 90 from the motor 31.

[0098] Hereinafter, a state in which two elements are electrically connected may be simply referred to as a "connected state," or a state in which two elements are electrically disconnected may be referred to as a "disconnected state."

[0099] For example, in this embodiment, the switching circuit 8 is composed of a first circuit 8A, a second circuit 8B and a third circuit 8C. The first circuit 8A switches the electrical connection between the first component 90A and the motor 31, the second circuit 8B switches the electrical connection between the second component 90B and the motor 31, and the third circuit 8C switches the electrical connection between the third component 90C and the motor 31.

[0100] The first circuit 8A, the second circuit 8B, and the third circuit 8C can each be formed of a relay circuit whose contacts are opened and closed in response to a control signal received from the controller 100. The first circuit 8A to the third circuit 8C forming the switching circuit 8 are switched to either a "connected state" or a "disconnected state" based on a control signal received from the controller 100.

[0101] For example, by connecting all of the first circuit 8A, the second circuit 8B, and the third circuit 8C, the three battery assemblies 90 are connected in parallel to the motor 31 .

[0102] On the other hand, consider a case where one of the first circuit 8A, the second circuit 8B, and the third circuit 8C is connected, and the remaining circuits are disconnected. In this case, only the one battery pack 90 that is connected is connected to the motor 31, and the remaining battery packs 90 that are disconnected are electrically disconnected from the motor 31.

[0103] <2. Details of Secondary Batteries>

[0104] Figure 3A It is a perspective view illustrating the structure of the battery cell 91 . Figure 3B 2 is a cross-sectional view illustrating the structure of a battery cell 91 . Figure 3B The cross section is equivalent to the cross section along the front-back direction and the up-down direction.

[0105] like Figure 2As shown, each of the plurality of battery cells 91 constituting each battery assembly 90 has a plate shape. These battery cells 91 are housed in a box-shaped assembly container 90a in a state of being arranged in the front-back direction.

[0106] Specifically, within each battery assembly 90, multiple battery cells 91 are arranged with their longitudinal sides aligned along the vehicle width, their transverse sides aligned along the vehicle height, and their thickness aligned along the vehicle front-to-rear direction. This arrangement minimizes the vehicle height dimension of each battery assembly 90 while maximizing its vehicle width (longitudinal) dimension.

[0107] Furthermore, an external force that restrains the battery cells 91 housed in each assembly container 90 a in the front-rear direction acts on the plurality of battery cells 91 housed in each assembly container 90 a through the assembly container 90 a or another member independent of the assembly container 90 a .

[0108] And, as Figure 3A As shown, each of the multiple battery cells 91 has a longer dimension La along its long side than its dimension Lb along its short side. In this embodiment, dimension La along its long side is at least three times the dimension Lb along its short side. Each battery cell 91 has a high aspect ratio. Each battery cell 91 can also be referred to as a blade battery or blade cell.

[0109] Furthermore, tabs 91A and 91B corresponding to the positive and negative electrodes of the battery cells 91 are arranged at both ends in the longitudinal direction of each of the plurality of battery cells 91 .

[0110] More specifically, each battery cell 91 is formed by alternately stacking negative electrode sheets 92 and positive electrode sheets 93. The alternately stacked negative electrode sheets 92 and positive electrode sheets 93 are housed in a Figure 3A The cell container 94 is shown. Each battery cell 91 is a so-called lithium-ion battery that utilizes the movement of lithium ions between electrodes.

[0111] like Figure 3B As shown, the negative electrode sheet 92 includes a current collector 92a, an active material 92b, and a separator 92c. The current collector 92a and the active material 92b constitute a so-called "negative electrode." The negative electrode sheet 92 extends long in the vehicle width direction.

[0112] The current collector 92a is a thin plate extending perpendicularly to the stacking direction. One of the ends of the current collector 92a protrudes out of the cell container 94, for example, through an opening located on one side of the cell container 94 in the longitudinal direction. This protrusion forms the negative electrode tab 91A.

[0113] Active material 92b is applied to the surface of current collector 92a. Active material 92b on the negative electrode side contains silicon (Si). The negative electrode composed of active material 92b and current collector 92a faces positive electrode sheet 93 via separator 92c, for example.

[0114] Specifically, the active material 92b constituting the negative electrode active material is a mixture of a Si-based active material and a carbon (C)-based active material. The Si-based active material is composed of, for example, SiO, and the C-based active material is composed of, for example, graphite.

[0115] like Figure 3B As shown, the positive electrode sheet 93 includes a current collector 93a and an active material 93b. The current collector 93a and the active material 93b constitute a so-called "positive electrode." The positive electrode sheet 93 extends long in the vehicle width direction.

[0116] The current collector 93a is a thin plate extending in a direction perpendicular to the stacking direction. One of the ends of the current collector 93a protrudes out of the cell container 94, for example, through an opening located on the other longitudinal side of the cell container 94. This protrusion constitutes the positive electrode tab 91B.

[0117] The active material 93b is applied to the surface of the current collector 93a. The positive electrode composed of the active material 93b and the current collector 93a faces the active material 92b and the current collector 92a of the negative electrode sheet 92 via a separator 92c, for example.

[0118] Furthermore, an electrolyte 95 is sealed in the cell container 94. Lithium ions move between the electrodes via this electrolyte 95. By applying an external current to the battery cell 91, the lithium ions migrate toward the negative electrode. This migration of lithium ions creates a potential difference between the negative and positive electrodes. This potential difference, generated by the external power supply, is equivalent to charging the battery cell 91.

[0119] Furthermore, the potential difference is eliminated by the movement of lithium ions from the negative electrode to the positive electrode. At this point, current flows from the battery cell 91 to the outside. Eliminating the potential difference by supplying power to the outside is equivalent to discharging the battery cell 91.

[0120] <2. Control device structure>

[0121] Figure 4 This is a block diagram illustrating the configuration of a control device 1 for a secondary battery 9. The control device 1 includes switches such as an IG switch 111 and a mode selection switch 112, sensors such as an SOC sensor 121, a notification unit 130, a controller 100, and the aforementioned switching circuit 8.

[0122] The IG switch 111 is a switch for energizing the drive source 3 of the vehicle V. The IG switch 111 is electrically connected to the controller 100. When the IG switch 111 is operated, an electrical signal for switching the operating mode of the vehicle V between "IG-ON" and "IG-OFF" is input to the controller 100. The IG switch 111 can also be referred to as a power switch or an ignition switch.

[0123] The mode selection switch 112 is a switch for switching the discharge mode of the secondary battery 9. The mode selection switch 112 is electrically connected to the controller 100. When the mode selection switch 112 is operated, an electrical signal corresponding to the operation is input to the controller 100. The discharge mode will be described in detail later.

[0124] Furthermore, the mode selection switch 112 may be formed on a touch-panel liquid crystal panel or an organic EL panel, or may be formed as a physical switch such as a button or a toggle switch. In the present embodiment, the mode selection switch 112 may also be displayed on a touch panel 150 that is located at a different position from the display device 140.

[0125] "IG-OFF" is a mode used when the vehicle V is not traveling (specifically, when the power to the drive source 3 is disconnected), such as when the vehicle is parked or unused. In this mode, the charging and discharging of the secondary battery 9 is restricted. In other words, in this mode, the secondary battery 9 and the drive source 3 are electrically disconnected (the electrical connection is severed). As a result, both the power supply from the secondary battery 9 to the drive source 3 and the power supply from the drive source 3 to the secondary battery 9 are cut off.

[0126] "IG-ON" is a mode primarily used when the vehicle V is traveling (particularly, when power is supplied to the drive source 3). In this mode, charging and discharging of the secondary battery 9 are permitted. In other words, in this mode, the secondary battery 9 and the drive source 3 are energized (electrically connected). As a result, both power supply from the secondary battery 9 to the drive source 3 and power supply from the drive source 3 to the secondary battery 9 are permitted.

[0127] The SOC sensor 121 detects the SOC of each of the plurality of battery assemblies 90. Figure 4 Although omitted, each of the plurality of battery assemblies 90 is individually equipped with an SOC sensor 121. In other words, the SOC sensor 121 individually detects the SOC of each of the plurality of battery assemblies 90. The SOC sensor 121 is an example of a state sensor according to the present embodiment.

[0128] Specifically, the SOC sensor 121 outputs a signal corresponding to the SOC for each battery assembly 90. More specifically, the SOC sensor 121 outputs a signal corresponding to the SOC based on the measured value of the open circuit voltage (OCV). The SOC sensor 121 can be configured as a voltage sensor capable of measuring circuit voltage. The SOC sensor 121 is electrically connected to the controller 100. The SOC sensor 121 inputs its detection signal to the controller 100.

[0129] The notification unit 130 is electrically connected to the controller 100. The notification unit 130 is configured to notify the occupant of the vehicle V of information related to a process performed by the controller 100, which will be described later.

[0130] Specifically, the notification unit 130 according to this embodiment is electrically connected to a display device 140 located in front of the driver's seat of the vehicle V. The display device 140 includes a screen that displays indicators such as the tachometer, the remaining battery level, and the like. The notification unit 130 notifies the occupants of the aforementioned information by controlling the display content on the screen of the display device 140.

[0131] The controller 100 is composed of hardware such as a processor 100a, a memory 100b, and an input / output bus 100c, and software such as a database and a control program. Figure 5 .

[0132] In addition, Figure 4 The control device 1 shows a single controller 100 , but the controller 100 may be constituted by various control modules mounted on the vehicle V, for example, a module (PCM) for controlling the drive source 3 .

[0133] The controller 100 executes processing related to the charge and discharge of the secondary battery 9 based on the signals input from the aforementioned switches and sensors. In order to execute such processing, the controller 100 has Figure 5 Multiple functional blocks are shown.

[0134] <3. Controller Details>

[0135] The controller 100 according to the embodiment is configured to switch the electrical connection between the plurality of battery assemblies 90 and the drive source 3 based on the detection signal of the SOC sensor 121 .

[0136] Specifically, if Figure 5 As shown, the controller 100 includes a first SOC determination unit 101 , a first control execution unit 102 , a second control execution unit 103 , a discharge mode control unit 104 , a second SOC determination unit 105 , a first information estimation unit 106 , and a second information estimation unit 107 .

[0137] (3-1. First SOC Determination Unit)

[0138] The first SOC determination unit 101 determines whether the SOC of at least one of the plurality of battery assemblies 90 is greater than or equal to a predetermined first reference value based on the detection signal of the SOC sensor 121. A "no" determination is equivalent to a case where the SOC of all of the plurality of battery assemblies 90 is less than the predetermined first reference value.

[0139] That is, it can be considered that the first SOC determination unit 101 determines whether the SOC of all the plurality of battery units 90 is less than the first reference value based on the detection signal of the SOC sensor 121 .

[0140] The first reference value is a reference value corresponding to an SOC less than a full charge. In this embodiment, the first reference value is set to an arbitrary value within the range of 10% to 30%, more specifically, 15% to 25%, relative to a fully charged state (100%). In the following description, the first reference value may be considered to be set to "first reference value = 20%" as a temporary setting.

[0141] The first SOC determination unit 101 determines whether the SOC of each battery unit 90 is equal to or greater than a first reference value for each of the plurality of battery units 90. An electrical signal indicating the determination result of the first SOC determination unit 101 is input to the first control execution unit 102, the second control execution unit 103, and the discharge mode control unit 104.

[0142] (3-2. First Control Execution Unit)

[0143] Figure 6A 、 Figure 6B and Figure 6C This diagram illustrates the first control. When the SOC of at least one battery unit 90 is equal to or greater than a first reference value, the first control execution unit 102 executes a predetermined first control. Specifically, the first control execution unit 102 executes the first control for battery units 90 whose SOC is equal to or greater than the first reference value among the plurality of battery units 90. The first control execution unit 102 executes the first control in response to control signals from the first SOC determination unit 101 and the discharge mode control unit 102.

[0144] Here, the first control refers to sequentially connecting the plurality of battery assemblies 90 to the motor 31 and sequentially discharging the plurality of battery assemblies 90 until the SOC of each battery assemblies 90 falls below a first reference value. The first control execution unit 102 sequentially causes each battery assembly 90 connected to the motor 31 to supply power to the motor 31. This first control can be performed by the first control execution unit 102 controlling the switching circuit 8 based on a detection signal from the SOC sensor 121.

[0145] For example, it is assumed that the SOC of all battery modules 90 is greater than the first reference value. In this case, the controller 100 first sets only the first module 90A to the connected state, and sets the second module 90B and the third module 90C to the disconnected state (see Figure 6A ). Thus, when the vehicle V is traveling, only the first assembly 90A discharges.

[0146] Then, it is assumed that the SOC of the first assembly 90A decreases to the first reference value. In this case, the controller 100 sets the second assembly 90B to the connected state after the first assembly 90A, and sets the third assembly 90C and the first assembly 90A to the disconnected state (see Figure 6B ). Thus, when the vehicle V is traveling, only the second assembly 90B discharges.

[0147] Then, it is assumed that the SOC of the second assembly 90B decreases to the first reference value. In this case, the controller 100 sets the third assembly 90C to the connected state following the second assembly 90B, and sets the first assembly 90A and the second assembly 90B to the disconnected state (see Figure 6C ). Thus, when the vehicle V is traveling, only the third assembly 90C is discharged.

[0148] (3-3. Second Control Execution Unit)

[0149] Figure 6D This diagram illustrates the second control. When the SOC of all battery assemblies 90 is less than a first reference value, the second control execution unit 103 executes a predetermined second control. Specifically, the second control execution unit 103 executes the second control for all of the plurality of battery assemblies 90. The second control execution unit 103 executes the second control in response to control signals from the first SOC determination unit 101 and the discharge mode control unit 104.

[0150] Here, the second control is a process of connecting a plurality of battery assemblies 90 to the motor 31 in parallel and discharging the plurality of battery assemblies 90 simultaneously (see Figure 6D The second control execution unit 103 causes the plurality of battery assemblies 90 connected to the motor 31 to simultaneously supply power to the motor 31. This second control can be performed by the second control execution unit 103 controlling the switching circuit 8 based on the detection signal of the SOC sensor 121.

[0151] The second control is set to start according to the selection of the discharge mode when the SOC of all the battery assemblies 90 is reduced to the first reference value by the first control.

[0152] (3-4. Discharge Mode Control Unit)

[0153] Figure 7This diagram illustrates multiple discharge modes. Discharge mode control unit 104 selects one discharge mode from the multiple discharge modes based on a setting input by the occupant. In this embodiment, the setting input by the occupant refers to an operation input to mode selection switch 112. Discharge mode control unit 102 selects one discharge mode from the multiple discharge modes, and the mode selection unit selects the discharge mode selected by the occupant via mode selection switch 112.

[0154] The discharge mode may be selected, for example, after the vehicle V is turned IG-ON and before the vehicle V starts traveling, or may be selected while the vehicle V is traveling based on a detection signal from the SOC sensor 121 as described later.

[0155] Then, the discharge mode control unit 104 selects and executes one of the first control and the second control based on the detection signal of the SOC sensor 121 to realize the selected discharge mode. The first control and the second control are executed by the first control execution unit 102 and the second control execution unit 103 described above.

[0156] Here, the plurality of discharge modes include a first mode and a second mode. The SOC ranges used in the secondary battery 9 in the first mode and the second mode are different. Figure 7 As shown, the lower limit values ​​of the SOC ranges are different between the SOC range R1 used in the first mode and the SOC range R2 used in the second mode.

[0157] The first mode allows discharge from a fully charged state (SOC = 100%) to a first reference value (SOC = 20%). When the first mode is selected, power supply from secondary battery 9 to motor 31 is stopped upon the SOC falling to the first reference value, thereby stopping vehicle V from traveling.

[0158] Therefore, in the first mode, the SOC of secondary battery 9 does not deplete below the first reference value. In the first mode, only the first control is executed. Specifically, the first mode allows discharge within SOC range R1, which has the first reference value as its lower limit, thereby maintaining the first control regardless of the detection signal from SOC sensor 121. This first mode is a discharge mode more suitable for suppressing degradation of secondary battery 9 than the second mode and can be referred to as a "degradation suppression mode."

[0159] The second mode is a discharge mode that allows discharge from a fully charged state (SOC=100%) to a second reference value. The second reference value is a reference value corresponding to an SOC smaller than the first reference value.

[0160] Specifically, the second reference value in this embodiment is set to SOC corresponding to the fully discharged state (=0%). When the second mode is selected, even if the SOC drops to the first reference value, the vehicle V continues traveling until the SOC reaches the second reference value (SOC=0%).

[0161] Therefore, in the second mode, the SOC of secondary battery 9 is depleted until it falls below the first reference value. In the second mode, the first and second controls are switched with the first reference value as the boundary. Specifically, the second mode allows discharge within the SOC range R2, which has the second reference value as the lower limit, thereby selectively using the first and second controls based on the detection signal from the SOC sensor 121. This second mode is a discharge mode more suitable for longer-distance travel of vehicle V than the first mode and can be referred to as a "long-distance travel mode."

[0162] (3-5. Second SOC Determination Unit)

[0163] The second SOC determination unit 105 determines whether the SOC of the battery assemblies 90 as a whole has dropped to a predetermined intermediate reference value based on the detection signal of the SOC sensor 121 .

[0164] The intermediate reference value is a predetermined value corresponding to an SOC that is set higher than the first reference value and lower than the fully charged state. In this embodiment, the intermediate reference value is set to a value higher than the first reference value and less than 40%, more specifically, higher than the first reference value and less than 35%. In the following description, the intermediate reference value may be considered to be set to "intermediate reference value = 30%" as a temporary setting.

[0165] For example, second SOC determination unit 105 calculates an average value of the SOC detected for each of the plurality of battery assemblies 90 and compares this average value with an intermediate reference value. If this average value falls below the intermediate reference value, second SOC determination unit 105 determines that the SOC of the plurality of battery assemblies 90 as a whole has fallen to a predetermined intermediate reference value. An electrical signal representing the determination result of second SOC determination unit 105 is input to second information estimation unit 107.

[0166] (3-6. First Information Estimation Unit)

[0167] Figure 8 1 is a diagram suitable for explaining the first information I1. The first information estimating unit 106 estimates the first information I1 based on various information related to the vehicle V. The first information estimating unit 106 controls the display device 140 via the notifying unit 130 to notify the occupant of the estimated first information I1.

[0168] The first information I1 is estimated and notified, for example, after the drive source 3 is activated (for example, after the vehicle V is turned IG-ON) and before the vehicle V starts traveling. When the occupant selects the first mode or the second mode, the first information I1 is composed of an index serving as a criterion for the selection.

[0169] Here, as Figure 8 As shown, the first information I1 is configured to include at least a first distance I11 , a second distance I12 , a first degradation indicator I13 , and a second degradation indicator I14 .

[0170] The first distance I11 represents the distance that the vehicle V can travel in the first mode. The second distance I12 represents the distance that the vehicle V can travel in the second mode. In the second mode, a wider SOC range is used than in the first mode (in other words, the depth of discharge in the second mode is deeper than that in the first mode). Therefore, the second distance I12 is longer than the first distance I11.

[0171] The first distance I11 can be estimated based on the current SOC of the entire secondary battery 9 , the amount of electric power available in the first mode, the torque load of the motor 31 , and the rotation speed of the motor 31 .

[0172] The second distance I12 can be estimated based on the current SOC of the entire secondary battery 9 , the amount of electric power available in the second mode, the torque load of the motor 31 , and the rotational speed of the motor 31 .

[0173] The first degradation indicator I13 indicates the degree of degradation of the maximum capacity of the secondary battery 9 at the time the vehicle has traveled the first distance I11. The first degradation indicator I13 indicates the amount of reduction in the maximum capacity (the maximum value of the battery capacity) of the secondary battery 9 at the time the vehicle has traveled the first distance I11. In this embodiment, the greater the reduction in maximum capacity, the greater the first degradation indicator I13.

[0174] For example, the maximum capacity (initial capacity) of the new secondary battery 9 is set to 100%, and the maximum capacity of the secondary battery 9 when the chargeable electric power amount is zero is set to 0%.

[0175] Furthermore, assuming that the current maximum capacity of secondary battery 9 (current capacity) is 90%, it is estimated that after traveling first distance I11, the maximum capacity will decrease to 87%. In this case, for example, a decrease of 3% (=90% - 87%) from the current capacity can be used as the first degradation indicator I13.

[0176] The first degradation indicator I13 can be estimated based on the current capacity, the current SOC of the entire secondary battery 9, the temperature of the secondary battery 9, the amount of power available in the first mode, etc. The current capacity is updated and recorded each time the secondary battery 9 is charged, based on the number of charge and discharge cycles.

[0177] The second degradation indicator I14 indicates the degree of degradation of the maximum capacity of the secondary battery 9 at the time the vehicle has traveled the second distance I12. The second degradation indicator I14 indicates the amount of reduction in the maximum capacity (the maximum value of the battery capacity) of the secondary battery 9 at the time the vehicle has traveled the second distance I12. In this embodiment, the greater the reduction in maximum capacity, the greater the second degradation indicator I14.

[0178] For example, the maximum capacity (initial capacity) of the new secondary battery 9 is set to 100%, and the maximum capacity of the secondary battery 9 when the chargeable electric power amount is zero is set to 0%.

[0179] Furthermore, assuming that the maximum capacity (current capacity) of secondary battery 9 is currently 90%, it is estimated that the maximum capacity has decreased to 85% after the second distance I12 has been traveled. In this case, for example, a decrease of "5% (=90% - 85%)" from the current capacity can be used as the second degradation indicator I14.

[0180] The second degradation indicator I14 can be estimated based on the current capacity, the current SOC of the entire secondary battery 9 , the temperature of the secondary battery 9 , the amount of power available in the second mode, etc. The current capacity is recorded each time the secondary battery 9 is charged.

[0181] In the second mode, a wider SOC range is used than in the first mode (in other words, the depth of discharge in the second mode is deeper than in the first mode). Furthermore, the current capacity remains the same when the first mode is selected as when the second mode is selected. Therefore, the degree of degradation of secondary battery 9 in the second mode is greater than in the first mode. The second degradation indicator I14 is greater than the first degradation indicator I13.

[0182] like Figure 8 As shown, by simultaneously displaying the first distance I11 and the first degradation indicator I13 associated with the first mode and the second distance I12 and the second degradation indicator I14 associated with the second mode, the occupant can compare and study whether to drive the vehicle V in the first mode suitable for suppressing degradation of the secondary battery 9 or in the second mode suitable for long-distance driving.

[0183] Moreover, if Figure 8As shown, the first information I1 is configured to include both a first residual value indicator I15 and a second residual value indicator I16. When estimating the first information I1, the first information estimating unit 106 estimates the first residual value indicator I15 and the second residual value indicator I16. The first information estimating unit 106 controls the display device 140 via the notification unit 130 to notify the occupant of the first information I1 including the first residual value indicator I15 and the second residual value indicator I16.

[0184] The first residual value indicator I15 represents the economic value of the secondary battery 9 at the completion of the first distance I11. The "economic value" here can refer to the retail price of the secondary battery 9 or the cost of replacing it. The first residual value indicator I15 can be the economic value of the secondary battery 9 at the completion of the first distance I11 or the change in that economic value.

[0185] For example, assume that the economic value of a new secondary battery 9 is $10,000. Furthermore, consider the case where, as in the example above, the current capacity at the time the battery has traveled the first distance I11 is estimated to have decreased from 90% to 87%. In this case, the first degradation indicator I13 can be estimated to be, for example, 3%.

[0186] In this case, the first residual value indicator I15, representing the change in economic value, can be estimated as "$300" by multiplying the aforementioned "$10,000" by the first degradation indicator I13. This estimated result can be interpreted as "the economic value of secondary battery 9 decreases by $300 when the first distance I11 is covered in the first mode."

[0187] The second residual value indicator I16 represents the economic value of the secondary battery 9 at the completion of the second distance I12. The "economic value" here can be the retail price of the secondary battery 9 or the replacement cost. The second residual value indicator I16 can be the economic value of the secondary battery 9 at the completion of the second distance I12 or the change in that economic value.

[0188] For example, assume that the economic value of a new secondary battery 9 is $10,000. Furthermore, consider the case where, as in the example above, the current capacity at the time the second distance I12 is traveled is estimated to have decreased from 90% to 85%. In this case, the second degradation indicator I14 can be estimated to be, for example, 5%.

[0189] In this case, the second residual value indicator I16, representing the change in economic value, can be estimated as "$500" by multiplying the aforementioned "$10,000" by the second degradation indicator I14. This estimated result can be interpreted as "when the second distance I12 is covered in the second mode, the economic value of the secondary battery 9 decreases by $500."

[0190] like Figure 8 As shown, by simultaneously displaying the first distance I11 and the first residual value indicator I15 associated with the first mode and the second distance I12 and the second residual value indicator I16 associated with the second mode, the occupant can compare from a financial point of view whether to drive the vehicle V in the first mode suitable for suppressing the degradation of the secondary battery 9 or in the second mode suitable for long-distance driving.

[0191] That is, it is difficult for general users to intuitively understand the first degradation indicator I13 and the second degradation indicator I14. By simultaneously displaying the first residual value indicator I15 and the second residual value indicator I16, the occupants can be prompted to make a judgment based on the length of the travel distance and the level of economic loss.

[0192] (3-7. Second Information Estimation Unit)

[0193] Figure 9 1 is a diagram for explaining the second information I2. The second information estimating unit 107 estimates the second information I2 based on various information related to the vehicle V. The second information estimating unit 107 controls the display device 140 via the notifying unit 130 to notify the occupant of the estimated second information I2.

[0194] The second information I2 is estimated and notified, for example, after the drive source 3 is activated (e.g., after the vehicle V is turned IG-ON) and the first mode is selected, while the vehicle V is traveling. The second information I2 may be notified, for example, when the second SOC determination unit 105 determines that the SOC of the plurality of battery assemblies 90 as a whole has fallen to the aforementioned intermediate reference value. The second information I2 is composed of an indicator that serves as a criterion for determining whether to switch from the first mode to the second mode while the vehicle V is traveling.

[0195] Here, if Figure 9 As shown, the second information I2 is configured to include at least an extended distance I21 and a third degradation indicator I22.

[0196] The extended distance I21 represents the extended distance that can be traveled when switching from the first mode to the second mode. The extended distance I21 may be obtained by, for example, subtracting the first distance I11 from the second distance I12, or may be estimated based on the torque load and rotational speed of the motor 31 at that time.

[0197] The third degradation indicator I22 indicates the degree of degradation of the maximum capacity of the secondary battery 9 at the completion of the extended distance I21. The third degradation indicator I22 is an indicator that indicates the amount of decrease in the maximum capacity (maximum battery capacity) of the secondary battery 9 at the completion of the extended distance I21. The third degradation indicator I22 can be, for example, a value obtained by subtracting the first degradation indicator I13 from the second degradation indicator I14, or it can be estimated based on the temperature of the secondary battery 9 at that time.

[0198] like Figure 9 As shown, by simultaneously displaying the extended distance I21 and the third degradation indicator I22 , the occupant can compare and consider whether to continue driving the vehicle V while maintaining the first mode or to continue driving the vehicle V after switching from the first mode to the second mode.

[0199] <4. Specific Example of Processing by Controller>

[0200] Figure 10A : is a flowchart showing a specific example of processing related to selection of the first mode and the second mode. Figure 11 1 is a diagram illustrating mode selection switch 112 on touch panel 150 .

[0201] First, in step S101, the controller 100 confirms that it is in the "IG-ON" state. This confirmation can be made based on whether the electric signal related to the IG switch 111 is input to the controller 100. If it is not in the "IG-ON" state, the controller 100 ends Figure 10A processing.

[0202] In the next step S102 , the controller 100 reads detection signals of sensors. The sensors whose signals are to be read include the SOC sensor 121 and the temperature sensor 122 .

[0203] In the next step S103, the controller 100 calculates the current charge capacity of the secondary battery 9 based on the detection signal from the SOC sensor 121. This calculation can be performed based on the detection signal from the SOC sensor 121, the initial capacity described above, and the current maximum capacity. As described later, the current maximum capacity is recorded each time the secondary battery 9 is charged.

[0204] In the next step S104, the first information estimating unit 106 estimates first information I1. The estimated first information I1 is composed of information related to the first mode and information related to the second mode. The first information related to the first mode includes a first distance I11, a first degradation indicator I13, and a first residual value indicator I15. Meanwhile, the second information related to the second mode includes a second distance I12, a second degradation indicator I14, and a second residual value indicator I16.

[0205] In the next step S105 , the first information estimating unit 106 controls the display device 140 via the notification unit 130 to display the first information I1 estimated in step S104 on the screen of the display device 140 .

[0206] In the next step S106, the discharge mode control unit 104 controls the display screen on the touch panel 150 to display the mode selection switch 112 (see FIG. Figure 11 The discharge mode control unit 104 receives the selection of the discharge mode by the occupant based on the setting input to the mode selection switch 112 .

[0207] In the next step S107, the controller 100 determines whether the first mode was selected in step S106. If the determination is "yes," the controller 100 advances the control process to step S108. If the process proceeds to step S108, the discharge mode control unit 104 sets the discharge mode to the first mode. The subsequent processing will be described in detail later.

[0208] On the other hand, if the determination in step S107 is “No”, the controller 100 advances the control process to step S109. When the process advances to step S109, the discharge mode control unit 104 sets the discharge mode to the second mode.

[0209] (4-1. Processing Related to the Second Mode)

[0210] Figure 10B is a flowchart illustrating processing associated with the second mode. Figure 10B The process shown is an example of Figure 10A A series of processing is performed when the control process enters step S109. Figure 10B The illustrated process is repeated during driving in the second mode.

[0211] First, in Figure 10B In step S201, the first SOC determination unit 101 and Figure 10ASimilarly, in step S102, the detection signal of the SOC sensor 121 is read. The first SOC determination unit 101 performs determination based on the read detection signal.

[0212] In the next step S202 , the discharge mode control unit 104 determines whether the SOC of at least one of the plurality of battery units 90 is equal to or greater than a predetermined first reference value based on the determination result of the first SOC determination unit 101 .

[0213] The discharge mode control unit 104 proceeds to step S203 if the determination in step S202 is “Yes”, and proceeds to step S204 if the determination is “No”.

[0214] In step S203, the discharge mode control unit 104 executes the first control via the first control execution unit 102. The first control execution unit 102 selects a battery pack 90 whose SOC is greater than the first reference value among the plurality of battery packs 90 and connects the battery pack 90 to the motor 31. When the processing of step S203 is completed, the controller 100 ends. Figure 10B When the IG-ON state is maintained, the controller 100 Figure 10B A series of processing is repeated in sequence starting from step S201.

[0215] In step S204, the discharge mode control unit 104 determines whether the SOC of all of the plurality of battery assemblies 90 is greater than or equal to a third reference value based on the determination result of the first SOC determination unit 101. The third reference value is a reference value that is higher than the SOC corresponding to a fully discharged state and lower than the first reference value. Specifically, the third reference value may be a value corresponding to an SOC of 10% or less, or more specifically, an SOC of 5% or less.

[0216] If the determination result in step S204 is “Yes”, the discharge mode control unit 104 skips step S205 and proceeds to step S206 . If the determination result in step S204 is “No”, the discharge mode control unit 104 proceeds to step S205 .

[0217] In step S205 , the controller 100 notifies the occupant of the parking and charging via the display device 140 , etc. When the notification is completed, the controller 100 advances the control process to step S206 .

[0218] In step S206, the discharge mode control unit 104 executes the second control via the second control execution unit 103. The second control execution unit 103 connects the plurality of battery assemblies 90 in parallel with the motor 31. When the processing of step S206 is completed, the controller 100 ends. Figure 10BAfter that, as long as the IG-ON state is maintained, the controller 100 Figure 10B A series of processing is repeatedly performed in sequence starting from step S201.

[0219] (4-2. Processing Related to the First Mode)

[0220] Figure 10C is a flowchart illustrating processing associated with the first mode. Figure 10C The process shown is an example of Figure 10A A series of processing is performed when the control process enters step S108. Figure 10C The illustrated process is repeated during driving in the first mode.

[0221] First, in Figure 10C In step S301, the discharge mode control unit 104 executes the first control via the first control execution unit 102. The first control execution unit 102 selects a battery pack 90 from the plurality of battery packs 90 whose SOC is greater than or equal to a first reference value and connects the battery pack 90 to the motor 31. After the processing of step S301 is completed, the controller 100 advances the control process to step S302.

[0222] In the next step S302, the second SOC determination unit 105 and Figure 10A Similarly, in step S102, the detection signal of the SOC sensor 121 is read. The second SOC determination unit 105 performs determination based on the read detection signal.

[0223] In the next step S303 , the controller 100 determines whether the SOC of the battery assemblies 90 as a whole has dropped to a predetermined intermediate reference value based on the determination result of the second SOC determination unit 105 .

[0224] If the determination result of step S303 is “yes”, the controller 100 proceeds to step S304. If the determination result of step S303 is “no”, the controller 100 ends the control process. Figure 10C After that, as long as the IG-ON state is maintained, the controller 100 Figure 10C A series of processing is repeatedly performed in sequence starting from step S301.

[0225] In the next step S304, the second information estimating unit 107 estimates the second information I2. The estimated second information I2 is configured to include the extended distance I21 and the third degradation indicator I22.

[0226] In the next step S305 , the second information estimating unit 107 controls the display device 140 via the notification unit 130 to display the second information I2 estimated in step S304 on the screen of the display device 140 .

[0227] In the next step S306, the discharge mode control unit 104 controls the display screen on the touch panel 150 to display the mode selection switch 112 (see FIG. Figure 11 The discharge mode control unit 104 receives selection of a discharge mode by the occupant, that is, an instruction to switch from the first mode to the second mode, based on a setting input to the mode selection switch 112 .

[0228] In the next step S307, the controller 100 determines whether the driving in the first mode is maintained in step S306. If the determination is "yes", the controller 100 advances the control process to step S308. If the control process enters step S308, the discharge mode control unit 104 maintains the discharge mode in the first mode and ends the operation. Figure 10C After that, as long as the IG-ON state is maintained, the controller 100 Figure 10C The series of processing shown in the same figure is repeatedly executed in sequence starting from step S301.

[0229] On the other hand, if the determination in step S307 is "No" (if an instruction to switch from the first mode to the second mode has been received), the controller 100 advances the control process to step S309. If the process advances to step S309, the discharge mode control unit 104 changes the discharge mode to the second mode. Thereafter, the controller 100 advances the control process to step S309. Figure 10C Step S09 Figure 10B In this case, a series of processing from step S201 in the same figure is started.

[0230] <5. Significance of each control>

[0231] As described above, according to the above embodiment, the controller 100 executes the first control (see Figure 7 and Figure 10B By executing the first control, the number of battery cells 91 subject to charge and discharge can be minimized compared to when multiple battery assemblies 90 are connected in parallel. This reduces the frequency of collisions and contractions of battery cells 91 caused by intercalation reactions, thereby suppressing performance degradation of secondary battery 9 due to exfoliation of negative electrode active material 92b.

[0232] In addition, when the SOC is less than the first reference value, and the depth of discharge of each battery cell 91 is deep, there is a concern that the C rate becomes high, which may cause performance degradation from a different perspective than peeling. Figure 7As clearly stated in , the controller 100 does not execute the first control under the condition that takes such concerns into consideration. This is particularly advantageous in suppressing the performance degradation of the secondary battery 9.

[0233] In addition, if Figure 7 and Figure 10B As shown in the example, when the depth of discharge of each battery cell 91 increases, multiple battery assemblies 90 are connected in parallel with the motor 31. This can suppress the C-rate when viewed per battery assembly 90, and further per battery cell 91, and is advantageous in suppressing performance degradation of the secondary battery 9. By switching the electrical connection according to the SOC, performance degradation of the secondary battery 9 can be minimized.

[0234] In addition, as reference Figure 7 As described above, the drivable distance in the first mode is shorter than that in the second mode by an amount equal to the lower limit of the first reference value. The first mode suppresses the performance degradation of the secondary battery 9 better than the second mode by an amount equal to the lower limit of the first reference value. The first and second modes are not designed to balance the drivable distance and the life of the secondary battery 9, but rather prioritize one over the other. The occupant can drive the vehicle V in either the first mode or the second mode.

[0235] By allowing the occupant to select the mode rather than being fixed to the first or second mode, flexible discharge control can be achieved according to the occupant's preference, the occupant's situation, etc. This improves the usability of the vehicle V.

[0236] In addition, if Figure 8 As illustrated, by notifying the occupant of the first information I1, the occupant can quantitatively understand the advantages of the first and second modes. This allows for flexible discharge control tailored to the occupant's preferences and circumstances, thereby improving the usability of the vehicle V.

[0237] Furthermore, when only the first distance I11 and the second distance I12 are displayed, it is easier to select the second mode, which allows for a longer travel distance. Simultaneously displaying the first degradation indicator I13 and the second degradation indicator I14 allows the occupant to quantitatively grasp the degree of degradation of secondary battery 9. This increases the frequency of selecting the first mode, which is beneficial for suppressing performance degradation of secondary battery 9.

[0238] In addition, if Figure 8 As illustrated, by further notifying the first residual value indicator I15 and the second residual value indicator I17, the occupant can more appropriately grasp the degree of degradation of the secondary battery 9. This increases the frequency of selecting the first mode, which is advantageous for suppressing performance degradation of the secondary battery 9.

[0239] In addition, if you use Figure 10C As described above, the controller 100 accepts the change from the first mode to the second mode even while the vehicle V is traveling. This allows for flexible discharge control in real time according to the occupant's situation, etc. This improves the usability of the vehicle V.

[0240] Furthermore, simply accepting the change to the second mode makes it easier to select the second mode, which allows for a longer mileage. By notifying the occupant of the second information I2 including the third degradation indicator I22, the occupant can quantitatively grasp the degree of degradation of the secondary battery 9. This increases the frequency of continuation of the first mode, which is beneficial for suppressing performance degradation of the secondary battery 9.

[0241] In addition, if you use Figure 10C As described above, the second information I2 can be notified to the occupant at an appropriate timing during travel of the vehicle V. As a result, the usability of the vehicle V can be improved.

[0242] In recent years, it has been found that the aforementioned peeling problem becomes more pronounced when Si-based active materials are used for the negative electrode active material 93 b. The structure of this embodiment is particularly effective when using active materials 93 b containing Si.

Claims

1. A secondary battery control device comprising a plurality of battery assemblies, each of which is composed of one or more battery cells and connected to a vehicle drive source, wherein power is supplied from the plurality of battery assemblies to the drive source, wherein the one or more battery cells each have a negative electrode containing a negative electrode active material, characterized in that: have: a state sensor that detects a parameter representing the SOC of each of the plurality of battery assemblies; and a controller that switches electrical connections between the plurality of battery assemblies and the drive source based on a detection signal from the state sensor, The controller determines whether the SOC of at least one of the plurality of battery modules is equal to or greater than a predetermined first reference value based on a detection signal of the SOC sensor. When the SOC is greater than or equal to the first reference value, the controller performs a first control for sequentially connecting the plurality of battery assemblies to the drive source and sequentially discharging the plurality of battery assemblies until the respective SOCs decrease to the first reference value.

2. The secondary battery control device according to claim 1, wherein: The controller determines whether the SOC of all the battery assemblies is less than the first reference value based on the detection signal of the state sensor. When the SOC is less than the first reference value, the controller performs a second control of connecting the plurality of battery assemblies in parallel to the driving source and discharging the plurality of battery assemblies simultaneously.

3. The secondary battery control device according to claim 2, wherein: The controller selects a discharge mode from a plurality of discharge modes set corresponding to the electrical connection based on a setting input by an occupant of the vehicle, The controller selects and executes one of the first control and the second control based on the detection signal of the state sensor to realize the selected one discharge mode. The multiple discharge modes include: a first mode for continuing the first control regardless of a detection signal of the SOC sensor by allowing discharge within an SOC range having the first reference value as a lower limit; as well as A second mode allows discharge within an SOC range having a second reference value as a lower limit, thereby separately using the first control and the second control according to a detection signal of the SOC sensor, the second reference value being set smaller than the first reference value.

4. The secondary battery control device according to claim 3, wherein: After the driving source is activated, The controller notifies the occupant of first information, the first information including: a first distance indicating a distance that the vehicle can travel in the first mode; a second distance indicating a distance that the vehicle can travel in the second mode; a first degradation indicator indicating a degree of deterioration of the maximum capacity of the secondary battery when the vehicle travels the first distance; and a second degradation indicator indicating the degree of deterioration when the vehicle travels the second distance. The controller accepts selection of the first mode or the second mode based on a setting input by the occupant.

5. The secondary battery control device according to claim 4, wherein: The controller estimates a first residual value indicator and a second residual value indicator based on the first degradation indicator and the second degradation indicator, respectively, the first residual value indicator indicating the economic value of the secondary battery after the first distance has been traveled, and the second residual value indicator indicating the economic value after the second distance has been traveled. The first information is configured to include both the first residual value indicator and the second residual value indicator.

6. The secondary battery control device according to claim 3, wherein: During travel of the vehicle when the first mode is selected, The controller notifies the occupant of second information, the second information including: an extension of the drivable distance when switching from the first mode to the second mode, and a third degradation indicator indicating a degree of degradation of the maximum capacity of the secondary battery when the extended distance is reached; The controller accepts a change from the first mode to the second mode based on a setting input by the occupant.

7. The secondary battery control device according to claim 6, characterized in that: When a predetermined value higher than the first reference value and lower than the fully charged state is set as the intermediate reference value, The controller determines whether the SOC of all the battery assemblies has decreased to the intermediate reference value based on the detection signal of the SOC sensor. The controller performs notification of the second information when the SOC decreases to the intermediate reference value.

8. The secondary battery control device according to any one of claims 1 to 7, wherein: The first reference value is set to an arbitrary value within a range of 10% to 30% relative to the fully charged state.

9. The secondary battery control device according to any one of claims 1 to 7, wherein: The negative electrode active material includes Si.

Images