Vehicle

Abstract

A vehicle capable of dispersing a load applied to a traction battery to extend the overall life. A vehicle including: a traction motor that drives a wheel; a traction battery that supplies power to the traction motor and has a plurality of battery modules including a plurality of battery cells; low-voltage electrical components that operate at a voltage lower than an output voltage of the traction battery; one or more processors; and a storage medium that stores a program executed by the processor, the program including one or more commands that cause the one or more processors to execute: a health degree calculation process that calculates a health degree of each of the battery modules; and a selection process that selects, based on a calculation result of the health degree obtained by the health degree calculation process, a battery module that supplies power to the low-voltage electrical components, i.e., a low-voltage power supply module, from among the plurality of battery modules.

Description

Technical Field

[0001] This invention relates to vehicles, and more particularly to control technology for driving batteries in vehicles. Background Technology

[0002] The technology described in Patent Document 1 below is as follows: a lithium-ion battery with a charging voltage of 3V (volt) is used as a node, and a group of four nodes is formed into an energy storage element. One of the groups is periodically selected to supply power to an auxiliary device that operates at 12V.

[0003] Furthermore, Patent Document 2 describes a technique in which, in a battery cell group consisting of four battery cells, the battery cell group with the highest charging rate and a usage frequency less than a predetermined value is selected to supply power to auxiliary equipment.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-026973

[0005] Patent Document 2: Japanese Patent Application Publication No. 2013-158109 Summary of the Invention

[0006] In a vehicle, there exists a battery that serves as a driving battery for supplying power to a motor for driving, and the battery module consists of multiple battery cells.

[0007] In such driving batteries, the degree of degradation varies from module to module, which may reduce the overall lifespan of the driving battery.

[0008] On the other hand, sometimes in vehicles, a separate battery consisting of lead-acid batteries or the like is installed as an auxiliary power source, separate from the driving battery.

[0009] However, separating the battery from the driving battery and installing a separate battery increases the number of vehicle parts, which is detrimental to vehicle lightweighting.

[0010] Therefore, the object of the present invention is to replace a portion of the battery module of the driving battery with an auxiliary battery, thereby extending the life of the driving battery and enabling the vehicle to operate without an auxiliary battery.

[0011] The vehicle of the present invention comprises: a driving motor for driving wheels; a driving battery for supplying power to the driving motor and having a plurality of battery modules, the battery modules including a plurality of battery cells; a low-voltage electrical component for operating at a voltage lower than the output voltage of the driving battery; one or more processors; and a storage medium storing a program executed by the processors, the program including one or more commands that cause the one or more processors to perform: a health calculation process for calculating the health of each battery module; and a selection process for selecting, based on the health calculation result obtained by the health calculation process, a battery module that supplies power to the low-voltage electrical component, i.e., a low-voltage power supply module, from the plurality of battery modules.

[0012] As described above, by selecting a low-voltage power supply module based on its health status, for example, a battery module with a lower health status than other battery modules can be selected as the low-voltage power supply module. The degradation progression of the battery module selected as the low-voltage power supply module is suppressed.

[0013] According to the present invention, a vehicle structure that does not require the installation of an auxiliary battery can be realized.

[0014] Furthermore, by distributing the load acting on each battery module, the rate of degradation of the overall driving battery can be suppressed, thus extending the lifespan of the driving battery. Attached Figure Description

[0015] Figure 1 This is a schematic block diagram of a vehicle according to an embodiment of the present invention.

[0016] Figure 2 This is a block diagram of a power supply system, including an electrical section, in a vehicle according to an embodiment.

[0017] Figure 3 This is a block diagram illustrating the structure of the BCU in an embodiment.

[0018] Figure 4 This is a conceptual diagram showing the state of the selection unit when the IG is off, in which the selection processing unit selects the first battery module as the low-voltage power supply module.

[0019] Figure 5 This is a conceptual diagram showing the state of the selection unit when the selection processing unit selects the first battery module as the low-voltage power supply module when ready.

[0020] Figure 6 This is a conceptual diagram showing the state of the selection unit when the IG is turned off, in which the selection processing unit selects the second battery module as the low-voltage power supply module.

[0021] Figure 7It is a graph showing the changes in the health of each battery module when the low-voltage power supply module is switched according to the implementation method.

[0022] Figure 8 This is a flowchart of the implementation method selection process.

[0023] (Explanation of reference numerals in the attached diagram)

[0024] 1. Storage battery for driving

[0025] 6. Selection Department

[0026] 7 Low-voltage electrical components

[0027] 11 Health Calculation Department

[0028] 12 Selection Processing Unit

[0029] 100 vehicles

[0030] BM battery module Detailed Implementation

[0031] Hereinafter, with reference to the accompanying drawings, the method of selecting the low-voltage power supply module for implementing the present invention will be described.

[0032] <1. Vehicle Structure>

[0033] Figure 1 This is a diagram illustrating a structural example of a vehicle 100 according to an embodiment of the present invention.

[0034] The vehicle 100 is equipped with a driving battery 1, an electrical circuit 2, a driving motor 4, and low-voltage electrical components 7.

[0035] The vehicle 100 may be any of the following types: EV (electric vehicle), PHEV (plug-in hybrid electric vehicle), or MHEV (mild hybrid electric vehicle). If the vehicle 100 is a hybrid vehicle, it is equipped with an engine.

[0036] Furthermore, in this embodiment, these vehicles, such as EV, PHEV, and MHEV, whose wheels are electrically driven, are sometimes collectively referred to as electric vehicles.

[0037] The driving battery 1 is composed of multiple battery modules BM, each BM comprising multiple battery cells, which serve as the power source for the driving motor 4. In this embodiment, the battery module BM, for example, has four battery cells.

[0038] Additionally, although the illustration is omitted, the battery module BM is equipped with voltage and current sensors for detecting charging capacity (SOC: State of Charge) and resistance value.

[0039] Circuit section 2 includes the power supply circuit for the driving battery 1 and the circuitry for the BCU (Battery Control Unit). The structure will be described in detail later.

[0040] The driving motor 4 is configured, for example, as an electric generator that operates on a voltage of about 200V to drive the wheels or operates on a voltage of about 48V to provide torque assistance to the engine.

[0041] The low-voltage electrical components 7 generally represent electrical components that operate at a rated voltage lower than that required by the driving motor 4, such as lamps, auxiliary motors, and various ECUs (Electronic Control Units) found in the vehicle 100. The rated voltage of the low-voltage electrical components 7 is, for example, around 12V.

[0042] <2. Structure of the Circuit Section>

[0043] Next, refer to Figure 2 Explain the structure of the circuit section 2 in vehicle 100.

[0044] The electrical circuit section 2 of the vehicle 100 includes a BCU 3, a repeater 5, a selector 6, an inverter 8, and a DC / DC converter 9.

[0045] In addition, Figure 2 In addition to circuit section 2, it is also shown Figure 1 The driving battery 1, driving motor 4, and low-voltage electrical components 7 are shown.

[0046] BCU 3, for example, is configured with a microcomputer, which includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The CPU executes programs stored in the ROM to perform various controls. Specifically, this includes the switching control processing of the repeater 5 when the IG (igniter) is turned on, and the switching control processing of the selection unit 6, which will be described later.

[0047] The repeater 5 is equipped with an electromagnetic repeater and is controlled by the BCU 3 to switch between a disconnected state, in which the power supply line from the driving battery 1 to the driving motor 4 is disconnected, and a non-disconnected state, in which the power supply line from the driving battery 1 to the driving motor 4 is not disconnected.

[0048] Therefore, in the IG-off state described later, the high-voltage circuit is disconnected, thus improving the safety of the vehicle by 100%.

[0049] The selection unit 6 selects one of the battery modules BM constituting the driving battery 1 to be de-energized from the low-voltage electrical component 7 according to the instructions of the selection processing unit 12 described later, and otherwise de-energizes the battery modules BM from each other.

[0050] The details of the selection method for the battery module BM, i.e., the low-voltage power supply module, which is connected to the low-voltage electrical component 7, will be explained in detail later.

[0051] Inverter 8 generates drive voltage for driving motor 4 based on DC voltage supplied from driving battery 1 and supplies it to driving motor 4.

[0052] DC / DC converter 9 is configured as a step-down DC / DC converter to step down the output voltage of driving battery 1.

[0053] In this example, even though the output voltage of the driving battery 1 is stepped down by the DC / DC converter 9, it can still supply power to the low-voltage electrical components 7.

[0054] <3. Functional Structure of BCU>

[0055] Next, refer to Figure 3 This explains the functional structure of BCU 3.

[0056] BCU 3 has a health calculation unit 11, a selection processing unit 12, and an IG determination unit 13.

[0057] The health calculation unit 11 calculates the health (SOH: State of Health) of each battery module BM constituting the driving battery 1.

[0058] There are two methods for calculating SOH: one based on the charging capacity when fully charged and the other based on the resistance value.

[0059] The method based on the SOC at full charge compares the SOC at full charge with a reference SOC, calculates the percentage decrease, and derives the SOH from this. The reference SOC, for example, is the SOC at full charge in the initial state of the battery module BM at the time of factory shipment.

[0060] Generally, electric vehicles such as EVs are driven only by the driving force of the driving motor 4. In order to emphasize the purpose of driving range, the driving battery 1 adopts a relatively large capacity battery.

[0061] Therefore, the method of calculating SOH based on the charging capacity when fully charged is suitable for electric vehicles that prioritize driving range.

[0062] In addition, the above-mentioned resistance-based method compares the resistance value of the driving battery 1 with a certain reference, calculates the increase by a certain percentage, and derives the SOH from this.

[0063] The reference value for the resistance value mentioned is, for example, the resistance value of the battery module BM in its initial state when it leaves the factory.

[0064] Generally, electric vehicles such as MHEVs use a driving motor to assist the engine's output and employ a relatively small-capacity driving battery.

[0065] Therefore, the SOH calculation method based on resistance value is suitable for electric vehicles that prioritize output.

[0066] The selection processing unit 12 performs a process based on the SOH of each battery module BM calculated by the health calculation unit 11 to select which battery module BM to use to supply power to the low-voltage electrical assembly 7.

[0067] In this embodiment, the battery module with the lowest SOH (hereinafter, the lowest health module) is selected as the low-voltage power supply module that supplies power to the low-voltage electrical component 7.

[0068] The selection processing unit 12 selects the low-voltage power supply module and controls the selection unit 6 so that power is supplied from the low-voltage power supply module to the low-voltage electrical assembly 7.

[0069] The IG determination unit 13 determines the IG status of vehicle 100.

[0070] In this embodiment, the IG determination unit 13 determines three states: IG off, IG on, and ready.

[0071] In vehicle 100, the state of IG changes depending on the user's operation of the start button or key operation.

[0072] The term "IG off" refers to the state where the vehicle 100 is not started. When the IG is off, the repeater 5 is disconnected, and the driving battery 1 is electrically disconnected.

[0073] The term "IG on" refers to the state where the user presses the start button once from the IG off state, or turns the button to the ACC position. At this time, the BCU 3 controls the power supply so that a portion of the battery module BM of the driving battery 1 supplies power to the low-voltage electrical components 7, while the repeater 5 remains disconnected.

[0074] The term "ready" refers to the state where the user presses the start button once from the IG (In-Gate) state, or turns the button to the IG position. In this state, the BCU 3 controls the supply of power from the driving battery 1 to the driving motor 4 by setting the repeater 5 to a non-disconnected state.

[0075] Furthermore, in actual vehicles, users can initiate an active start operation by pressing the start button while simultaneously pressing the brake pedal, thus transitioning from an IG-off state to a ready state. In an active start, the user experience is that the transition to the ready state occurs without going through the IG-on state. However, the actual IG state transition involves approximately several hundred milliseconds of IG-on time between the IG-off and ready states.

[0076] <4. Regarding the work of the selection department>

[0077] Next, refer to Figures 4 to 6 This section explains the structure and operation of the selection unit 6.

[0078] Furthermore, in this example, the driving battery 1 includes a first battery module BM1, a second battery module BM2, a third battery module BM3, and a fourth battery module BM4.

[0079] The selection unit 6 includes a positive terminal switch Sp1, a negative terminal switch Sm1, a positive terminal switch Sp2, a negative terminal switch Sm2, a positive terminal switch Sp3, a negative terminal switch Sm3, a positive terminal switch Sp4, a negative terminal switch Sm4, a bypass switch Sb12, a bypass switch Sb23, a bypass switch Sb24, and a bypass switch Sb24.

[0080] Except for the bypass switch Sb24, all other switches are configured as three-terminal switches with terminals t1, t2, and t3, and are configured to allow terminal t1 to be connected to either terminal t2 or terminal t3. The bypass switch Sb24 is a two-control switch with only terminals t1 and t2.

[0081] The positive terminal switch Sp1 is connected to the positive terminal of the first battery module BM1, the positive terminal t2 is connected to the positive side of the low-voltage electrical component 7, and the positive terminal t3 is connected to the positive side of the driving motor 4 and the positive side of the DC / DC converter 9 via the repeater 5. In addition, it is also connected to the positive terminal t3 of the bypass switch Sb12.

[0082] Terminal t1 of the negative terminal switch Sm1 is connected to the negative terminal of the first battery module BM1, terminal t2 is connected to the negative side of the low-voltage electrical component 7, and terminal t3 is connected to terminal t2 of bypass switch Sb12 and terminal t3 of bypass switch Sb23.

[0083] Terminal t1 of the positive terminal switch Sp2 is connected to the positive terminal of the second battery module BM2, terminal t2 is connected to the positive side of the low-voltage electrical component 7, and terminal t3 is connected to terminal t1 of the bypass switch Sb12.

[0084] Terminal t1 of the negative terminal switch Sm2 is connected to the negative terminal of the second battery module BM2, terminal t2 is connected to the negative side of the low-voltage electrical component 7, and terminal t3 is connected to terminal t2 of bypass switch Sb23 and terminal t1 of bypass switch Sb24.

[0085] Terminal t1 of the positive terminal switch Sp3 is connected to the positive terminal of the third battery module BM3, terminal t2 is connected to the positive side of the low-voltage electrical component 7, and terminal t3 is connected to terminal t1 of the bypass switch Sb23.

[0086] Terminal t1 of the negative terminal switch Sm3 is connected to the negative terminal of the third battery module BM3, terminal t2 is connected to the negative side of the low-voltage electrical component 7, and terminal t3 is connected to terminal t1 of the bypass switch Sb34.

[0087] Terminal t1 of positive terminal switch Sp4 is connected to the positive terminal of the fourth battery module BM4, terminal t2 is connected to the positive side of low-voltage electrical component 7, and terminal t3 is connected to terminal t2 of bypass switch Sb34 and terminal t2 of bypass switch Sb24.

[0088] Terminal t1 of the negative terminal switch Sm4 is connected to the negative terminal of the fourth battery module BM4, terminal t2 is connected to the negative side of the low-voltage electrical component 7, terminal t3 is connected to the negative side of the driving motor 4 and the negative side of the DC / DC converter 9 via the repeater 5, and is also connected to terminal t3 of the bypass switch Sb34.

[0089] Figure 4 This example illustrates the state of the selection unit 6, which selects the first battery module BM1 as the low-voltage power supply module when the IG is off.

[0090] exist Figure 4 In the indicated state, terminals t1 and t2 of the positive terminal switch Sp1 are connected, and terminals t1 and t2 of the negative terminal switch Sm1 are connected. Thus, the positive terminal of the first battery module BM1 selected by the selection processing unit 12 is connected to the positive side of the low-voltage electrical assembly 7, and the negative terminal of the first battery module BM1 is electrically connected to the negative side of the low-voltage electrical assembly 7.

[0091] At this time, terminals t1 and t3 of bypass switch Sb12 are connected, terminals t1 and t2 of bypass switch Sb23 are connected, and terminals t1 and t3 of bypass switch Sb34 are connected. Meanwhile, bypass switch Sb24 is in the open state. Therefore, the first battery module BM1 and the second battery module BM2 are electrically disconnected, while the second battery module BM2, the third battery module BM3, and the fourth battery module BM4 are electrically connected.

[0092] In addition, since the repeater 5 is in the off state, the battery modules BM and the driving motor 4 are electrically disconnected.

[0093] If the system switches to IG-on mode in this state, only the first battery module BM1 will supply power to the components in the low-voltage electrical assembly 7 that are capable of operating in the IG-on state.

[0094] Figure 5 Example from Figure 4 The state transitions to the ready state.

[0095] When ready, repeater 5 is in a non-disconnected state, thereby electrically connecting the driving battery 1 and the driving motor 4.

[0096] As described above, when the first battery module BM1 is selected as the low-voltage power supply module, the second battery module BM2, the third battery module BM3, and the fourth battery module BM4 are electrically connected and function as the power source for the driving motor 4.

[0097] exist Figure 5 In this state, since the repeater 5 is in a non-disconnected state, the positive terminal of the second battery module BM2 is electrically connected to the positive side of the driving motor 4, and the negative terminal of the fourth battery module BM4 is electrically connected to the negative side of the driving motor 4.

[0098] Therefore, the second battery module BM2, the third battery module BM3 and the fourth battery module BM4 can supply power to the driving motor 4.

[0099] The first battery module BM1, which is electrically connected to the low-voltage electrical component 7 via the selection unit 6, is the lowest health module determined by the selection processing unit 12 to have low SOH.

[0100] Therefore, even while the vehicle 100 is in motion, the first battery module BM1, which is electrically connected to the low-voltage electrical component 7, is not subjected to a high load, and the deterioration of the first battery module BM1 can be suppressed.

[0101] Figure 6 From Figure 5 The state transitions to IG off, and the state of the selection unit 6 when the low-voltage power supply module switches from the first battery module BM1 to the second battery module BM2 through the selection of the selection processing unit 12.

[0102] In this state, terminals t1 and t3 of the positive terminal switch Sp1 are connected, and terminals t1 and t3 of the negative terminal switch Sm1 are connected, thereby electrically disconnecting the first battery module BM1 from the low-voltage electrical assembly 7. Furthermore, terminals t1 and t2 of the positive terminal switch Sp2 are connected, and terminals t1 and t2 of the negative terminal switch Sm2 are connected, thereby electrically connecting the second battery module BM2 to the low-voltage electrical assembly 7. Moreover, by connecting terminals t1 and t3 of the bypass switch Sb23, the second battery module BM2 and the third battery module BM3 are electrically disconnected, and the first battery module BM1 and the third battery module BM3 are electrically connected. Additionally, in the figure, in the bypass switch Sb12 where no electrical connection is required, terminal t1 is not connected to either terminals t2 or t3; however, terminal t1 can also be connected to both terminals t2 and t3.

[0103] If the system switches to IG-on mode in this state, only the second battery module BM2 supplies power to the low-voltage electrical components 7 that are capable of operating when IG is on.

[0104] Furthermore, if the transition is further completed and ready, the repeater 5 becomes non-disconnected, so the first battery module BM1, the third battery module BM3, and the fourth battery module BM4 can supply power to the driving motor 4.

[0105] Although the illustration is omitted, when the selection processing unit 12 selects the third battery module BM3 or the fourth battery module BM4 as the low-voltage power supply module, the low-voltage power supply module can be switched by controlling the terminal connection state of the corresponding switch in the same manner as described above.

[0106] Furthermore, this embodiment shows a case where there are four battery modules BM, but the number of battery modules BM is not limited to four. This embodiment can be applied to any driving battery 1 that has two or more battery modules BM, regardless of the number of battery modules BM.

[0107] Furthermore, in the ready state, both the low-voltage power supply module and other battery modules BM are in use, so the voltage of each battery module BM is different. Therefore, the above-mentioned disconnection control is only performed when IG is off.

[0108] <5. When to switch to the low-voltage power supply module>

[0109] Next, refer to Figure 7 An example of when to switch the low-voltage power supply module is given, illustrating an example where the driving battery 1 has three modules: battery module A, battery module B, and battery module C.

[0110] First, in the initial state, the state of harmonics (SOH) of each battery module A, B, and C is 100%.

[0111] In this case, the selection processing unit 12 can arbitrarily select a low-voltage power supply module.

[0112] In this embodiment, since the SOH of each battery module BM decreases to different degrees, the low-voltage power supply module is switched on when the difference between the SOH of the battery module BM selected as the low-voltage power supply module and the SOH of the module with the lowest health reaches a predetermined value.

[0113] like Figure 7 As shown, the state of harmonics (SOH) of battery module A, which was initially selected as a low-voltage power supply module, decreased more slowly than that of other battery modules B and C.

[0114] If the SOH changes under this state, the difference between the SOH of the lowest health module (i.e., battery module C) at time T1 and the SOH of battery module A (selected as the low-voltage power supply module) reaches a predetermined value.

[0115] At time T1, the selection processing unit 12 selects the module with the lowest health status at time T1, namely battery module C, as the low-voltage power supply module, thereby switching the low-voltage power supply module from battery module A to battery module C.

[0116] Therefore, the decrease in SOH of battery module C after time T1 is slower than that before time T1.

[0117] If the SOH changes under this state, after time T1, the SOH of battery module A and battery module B will be lower than the SOH of battery module C. At time T2, the difference in SOH between battery module C, which is selected as the low-voltage power supply module, and battery module B, which is the module with the lowest health, will reach a predetermined value.

[0118] At time T2, the selection processing unit 12 selects the module with the lowest health status at time T2, namely battery module B, as the low-voltage power supply module.

[0119] Therefore, the decrease in SOH of battery module B after time T2 is slower than that before time T2.

[0120] If the SOH changes under this state, the SOH of battery module A and battery module C will be lower than the SOH of battery module B. At time T3, the difference between the SOH of battery module B (selected as a low-voltage power supply module) and the lowest health module (i.e., battery module C) will reach a predetermined value.

[0121] At time T3, the selection processing unit 12 selects the module with the lowest health status at time T3, namely battery module C, as the low-voltage power supply module.

[0122] As described above, whenever the difference between the SOH of the low-voltage power supply module and the module with the lowest health reaches a predetermined value, the battery module BM that becomes the low-voltage power supply module is switched over.

[0123] Therefore, the load applied to the driving battery 1 can be distributed among the battery modules BM, thus improving the overall lifespan of the driving battery 1.

[0124] Furthermore, although it will be described later that when the IG is on, it is determined whether the difference in State of Health (SOH) between the low-voltage power supply module and the module with the lowest health is above a predetermined value, the actual switching control is performed when the IG is off. Therefore, if the difference in SOH between the low-voltage power supply module and other battery modules (BM) exceeds a predetermined value in the ready state, the low-voltage power supply module will also be switched on the next time the IG is turned off.

[0125] <6. Selection Process Flow Performed by the Selection Processing Department>

[0126] Next, refer to Figure 8 The following describes the selection process executed by the selection processing unit 12. The CPU of BCU 3 executes the selection process described below based on the program stored in the aforementioned ROM, etc.

[0127] First, in step S101, BCU 3 determines whether vehicle 100 is in the IG-enabled state. If it is determined that the IG is not enabled, BCU 3 repeats the process of step S101. If it is determined that the IG is enabled, BCU 3 transfers the process to the subsequent step S102.

[0128] In step S102, BCU 3 determines whether the difference in SOH between the low-voltage power supply module and the lowest health module is above a predetermined value.

[0129] In step S102, if the difference in SOH between the low-voltage power supply module and the module with the lowest health is determined to be no greater than a predetermined value, BCU 3 ends. Figure 8 The selection process is shown.

[0130] On the other hand, in step S102, if it is determined that the difference between the SOH of the low-voltage power supply module and the lowest health module is above a predetermined value, BCU 3 will transfer the processing to the subsequent step S103.

[0131] In step S103, BCU 3 determines whether vehicle 100 has reached a ready state.

[0132] If the system determines that the user has not reached a ready state, i.e., the user has still performed the IG shutdown operation, BCU 3 will terminate. Figure 8 The selection process is shown.

[0133] On the other hand, if it is determined that the state is ready, BCU 3 will transfer the processing to the subsequent step S104.

[0134] In step S104, BCU 3 determines whether vehicle 100 is in an IG-off state. If it is determined that the IG is not off, BCU 3 repeats step S104. If it is determined that the IG is off, BCU 3 transfers the processing to the subsequent step S105.

[0135] In step S105, BCU 3 performs a process to equalize the SOC of all units.

[0136] One approach is to equalize the SOC of the cells with the lowest SOC by using resistors or other methods to reduce the SOC of the other cells.

[0137] Because the low-voltage power supply module and other battery modules BM are used differently, there is a high possibility of uneven State of Charge (SOC). When supplying power to the driving motor 4, uneven SOC among the battery modules BM may adversely affect the control of the driving battery 1.

[0138] As an example of adverse effects, suppose N battery modules BM are used to supply power to the driving motor 4, and one of the N battery modules BM has a low SOC. Since the vehicle uses all battery modules BM except the low-voltage power supply module to supply power to the driving motor 4, if the battery module BM with the lowest SOC cannot be used due to its low SOC, then the remaining battery modules BM also cannot be used regardless of whether they have a remaining SOC.

[0139] To avoid this situation, whenever the IG is turned off, BCU 3 performs SOC equalization for each battery cell that constitutes each battery module BM in step S105.

[0140] After completing step S105, BCU 3 will transfer the processing to the subsequent step S106.

[0141] In step S106, based on the determination result of step S102, BCU 3 selects the low-voltage power supply module at the time of step S102 for driving, selects the module with the lowest health at the time of step S102 as the low-voltage power supply module, and sends a switching instruction to the selection unit 6.

[0142] The selection process ends when the BCU 3 instruction is completed.

[0143] <7. Variations>

[0144] Furthermore, the implementation method is not limited to the specific examples described above, and various modified structures may be adopted.

[0145] For example, in the above embodiment, the IG determination unit 13 is configured to calculate the difference between the SOH of the low-voltage power supply module and the SOH of the module with the lowest health whenever it determines that the IG is turned on. However, as a first variation, for example, the difference between the SOH of the low-voltage power supply module and the module with the lowest health can be calculated at a certain period of time, such as every few months, and the battery module BM with the lowest health at the time of calculation is selected as the low-voltage power supply module.

[0146] Generally, the State of Harmony (SOH) of a driving battery does not decrease significantly during a single trip, but rather decreases over time. Therefore, instead of calculating the SOH difference every time the IG (Inlet Gauge Switch) is turned on by user operation, it can be calculated approximately once every few months.

[0147] Therefore, it is not necessary to calculate the difference in SOH between the low-voltage power supply module and the lowest health module every time the IG is turned on, which can reduce the processing burden of BCU 3.

[0148] Furthermore, especially when the SOH is calculated based on the resistance value of the battery module, if the SOH is calculated only when calculating the difference between the SOH of the low-voltage power supply module and the module with the lowest health, the execution frequency of processing that would otherwise be a load on the battery module through which current flows can be reduced.

[0149] <8. Summary>

[0150] As described above, the vehicle 100 of the embodiment includes: a driving motor 4 for driving wheels; a driving battery 1 for powering the driving motor 4 and having multiple battery modules BM, each battery module BM including multiple battery cells; a low-voltage electrical component 7 for operating at a voltage lower than the output voltage of the driving battery 1; one or more processors; and a storage medium storing a program executed by the processor, the program including one or more commands that cause the one or more processors to perform: a health calculation process for calculating the health of each battery module BM; and a selection process for selecting, based on the health calculation result obtained by the health calculation process, a battery module BM that supplies power to the low-voltage electrical component 7, i.e., a low-voltage power supply module.

[0151] Therefore, instead of using all the battery modules for vehicle propulsion, one of the battery modules is used as an auxiliary battery, which can achieve a battery-free operation and suppress poor vehicle starting caused by auxiliary battery problems.

[0152] In addition, while general auxiliary batteries need to be replaced every few years, high-voltage batteries, such as driving batteries 1, are precisely controlled and therefore are rarely replaced except in case of failure or when they reach the end of their lifespan (about 20 years), thus reducing the frequency of maintenance for users.

[0153] In the vehicle 100 of the embodiment, the command is, as a selection process, to cause one or more processors to execute a command to select the battery module BM with the lowest health as the low-voltage power supply module.

[0154] In this way, by selecting the module with the lowest health status as the auxiliary battery, the overall load of the driving battery 1 can be distributed, and the rate of deterioration can be suppressed.

[0155] In the vehicle 100 of the embodiment, the command is to cause one or more processors to execute a process for calculating the health of the battery module BM based on the charging capacity when fully charged, as a health calculation process.

[0156] Thus, by calculating the percentage reduction in charging capacity from the charging capacity when the driving battery 1 is fully charged, the SOH of the driving battery 1 can be calculated based on the SOC when fully charged, which is related to the vehicle's driving range.

[0157] In particular, this calculation method applies to the case of vehicle 100, which is an electric vehicle with a relatively large capacity driving battery 1 that prioritizes driving range.

[0158] In the vehicle 100 of the embodiment, the command is to cause one or more processors to execute a process for calculating the health of the battery module BM based on the resistance value as a health calculation process.

[0159] Thus, by using the resistance value of the driving battery 1 to calculate the SOH, the SOH can be calculated based on the resistance value related to the vehicle's output.

[0160] In particular, this calculation method applies to the case of vehicle 100, which is an electric vehicle that prioritizes output and has a relatively small capacity driving battery 1.

[0161] In the vehicle 100 of the embodiment, the command is to cause one or more processors to execute a reselection process that, after selecting a low-voltage power supply module, reselects a low-voltage power supply module based on the result of a calculation of the health of battery modules BM that were not selected as low-voltage power supply modules.

[0162] In this case, the battery module BM with the lowest SOH is selected as the low-voltage power supply module from the battery modules BM that have never been selected as low-voltage power supply modules.

[0163] Therefore, battery modules with low SOH (Surface Area Harm) can be selected as low-voltage power supply modules.

[0164] Therefore, the overall SOH of the driving battery 1 can be reduced slowly, thus extending the overall lifespan of the driving battery 1.

[0165] Furthermore, in the above-described embodiment, the vehicle 100 replaces the low-voltage power supply module when the difference in State of Health (SOH) between the low-voltage power supply module and the module with the lowest health status exceeds a predetermined value. However, the difference in SOH can be calculated periodically, and the battery module BM with the lowest SOH at the calculation time can be selected as the low-voltage power supply module.

Claims

1. A vehicle, comprising: A motor that drives the wheels; A driving battery that supplies power to the driving motor and has multiple battery modules, each battery module comprising multiple battery cells; Low-voltage electrical components operate at a voltage lower than the output voltage of the driving battery; One or more processors; as well as The storage medium stores a program executed by the processor. The program includes one or more commands. The command causes the one or more processors to execute: Health calculation processing: Calculate the health status of each battery module; The selection process involves selecting, based on the health calculation result obtained through the health calculation process, the battery module that supplies power to the low-voltage electrical components, namely the low-voltage power supply module, from among the plurality of battery modules. as well as The switching process switches the battery module that supplies power to the low-voltage electrical components to the low-voltage power supply module selected in the selection process. The switching process is performed when the igniter is off. The command, as the selection process, causes the one or more processors to perform the process of selecting the battery module with the lowest health status as the low-voltage power supply module. If the difference in SOH between the battery module supplying power to the low-voltage electrical components and the battery module with the lowest health is determined to be greater than a predetermined value, the command causes the one or more processors to perform the switching process.

2. The vehicle according to claim 1, wherein, The command, as part of the health calculation process, causes the one or more processors to perform a process that calculates the health of the battery module based on its charging capacity when fully charged.

3. The vehicle according to claim 1, wherein, The command, as part of the health calculation process, causes the one or more processors to perform a process that calculates the health of the battery module based on the resistance value of the battery module.

4. The vehicle according to claim 1 or 2, wherein, The command causes the one or more processors to perform a reselection process after selecting the low-voltage power supply module, based on the result of calculating the health status of the battery modules that were not selected as the low-voltage power supply module, and then reselecting the low-voltage power supply module.

5. The vehicle according to claim 3, wherein, The command causes the one or more processors to perform a reselection process after selecting the low-voltage power supply module, based on the result of calculating the health status of the battery modules that were not selected as the low-voltage power supply module, and then reselecting the low-voltage power supply module.

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