Battery management device

Abstract

Regarding battery management devices that manage the operation of electric vehicle batteries, this invention provides a technology that can reduce the State of Charge (SOC) of electric vehicle batteries at the time of shipment. [Solution] The battery management device according to this disclosure comprises one or more processors that limit the output of the battery. The one or more processors are configured to relax the battery output limit until the electric vehicle is transported after shipment.

Description

Technical Field

[0001] The present disclosure relates to a battery management device that manages a battery of an electric vehicle.

Background Art

[0002] Patent Document 1 discloses a control device that executes control to temporarily increase the output limit of a battery under predetermined conditions when starting an internal combustion engine (engine) or when the accelerator pedal is depressed deeply in a hybrid vehicle equipped with an internal combustion engine (engine) and an electric motor (motor).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, the demand for electric vehicles that run on electric energy stored in a battery has been increasing, and the production volume of electric vehicles has been expanding. In the production of electric vehicles, the production cost can be reduced by reducing the state of charge (SOC) of the battery at the time of shipment from the production factory. This is because the cost associated with charging the battery in the production process can be reduced.

[0005] On the other hand, vehicles, including electric vehicles, are transported by suitable means of transport (e.g., car carriers, ships) after being shipped from the production plant and delivered to dealers. During vehicle shipment and transport, vehicles need to be temporarily started and driven, such as moving within a motor pool or getting into the transport vehicle. Therefore, especially for electric vehicles, the energy required until the transport is completed must be supplied by the battery's State of Charge (SOC) at the time of shipment. Furthermore, electric vehicles need to maintain an SOC that allows for smooth operation during transport.

[0006] One of the purposes of this disclosure is to provide a technology that can reduce the State of Charge (SOC) of electric vehicle batteries at the time of shipment. [Means for solving the problem]

[0007] One aspect of this disclosure relates to a battery management device for managing the operation of an electric vehicle battery. The battery management device comprises one or more processors that limit the output of the battery. The one or more processors are configured to relax the output limit of the battery until the electric vehicle is transported after shipment. [Effects of the Invention]

[0008] According to this disclosure, the battery output limit is relaxed until the electric vehicle is transported after shipment. This reduces the State of Charge (SOC) of the electric vehicle at shipment. As a result, the production cost of the electric vehicle can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a conceptual diagram illustrating the outline of the technical features of the battery management device according to this embodiment. [Figure 2] This figure shows an example of a map that defines output limit values ​​related to battery output limitations. [Figure 3] This figure shows an example of the configuration of an electric vehicle to which the battery management device according to this embodiment is applied. [Figure 4] This figure shows an example of the functional configuration of the battery management device according to this embodiment. [Figure 5] This flowchart shows the processing flow of the process executed by the restriction relaxation determination unit of the battery management device according to this embodiment. [Figure 6] This flowchart shows the processing flow of the process performed by the restriction relaxation determination unit related to the modified form. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and their descriptions are simplified or omitted.

[0011] 1. Overview Figure 1 is a conceptual diagram illustrating the outline of the technical features of the battery management device 101 according to this embodiment. The battery management device 101 according to this embodiment manages the operation of the battery 14 of the electric vehicle 100. The technical features of the battery management device 101 according to this embodiment relate to the management of the battery 14 from the time the electric vehicle 100 is shipped from the production plant P1 until it is transported and delivered to the distributor P2. In this embodiment, the electric vehicle 100 is a so-called battery electric vehicle (BEV) that runs on the electrical energy stored in the battery 14.

[0012] In the production of electric vehicle 100, production costs can be reduced by lowering the State of Charge (SOC) at the time of shipment from production plant P1. This is because the costs associated with charging the battery 14 during the production process (e.g., time, equipment, and space) can be reduced. This is also true when only the installation of the battery 14 takes place at production plant P1, because the costs associated with charging can be reduced at the plant that produces the battery 14.

[0013] On the other hand, after the electric vehicle 100 is shipped from the production plant P1, it will be transported by a suitable means of transport. During this time, the electric vehicle 100 will need to be temporarily started and driven, such as moving within the motor pool or getting into the transport vehicle. Therefore, the electric vehicle 100 must replenish the energy required until the transport is completed with its State of Charge (SOC) at the time of shipment. Furthermore, the electric vehicle 100 needs to maintain an SOC that allows it to run with sufficient driving force for smooth transport until the transport is completed. Generally, in the management of the battery 14 of the electric vehicle 100, output limits are placed on the battery 14 according to its SOC and temperature for the purpose of protecting components and suppressing degradation. Due to this output limit, if the SOC drops excessively, the output of the battery 14 becomes insufficient, causing the electric vehicle 100 to run slowly or even become unable to run. As a result, smooth transport will be hindered.

[0014] The State of Charge (SOC) at the time of shipment is set considering the circumstances described above. The graph in Figure 1 shows an example of the pattern of change in SOC from the time the electric vehicle 100 is shipped until transportation is completed. Patterns E1 and E2 have different SOCs at the time of shipment. Specifically, the SOC at the time of shipment in pattern E1 is SCp, and the SOC at the time of shipment in pattern E2 is SCa, which is lower than SCp. In the graph in Figure 1, LCp represents the lower limit of SOC at which the vehicle can run with sufficient driving force (hereinafter referred to as the "required charge rate"). That is, the SOC must be maintained at or above LCp until transportation is completed. Here, it can be seen that in pattern E2, where the SOC at the time of shipment is SCa, the SOC cannot be maintained at or above LCp. On the other hand, in pattern E1, where the SOC at the time of shipment is SCp, the SOC can be maintained at or above LCp. Therefore, in the patterns shown in the graph in Figure 1, when the required charge rate is LCp, the SOC at the time of shipment is set to, for example, SCp.

[0015] The required charge level is determined by the battery management device 101 from a map or lookup table that defines the output limit values ​​related to output limiting. Typically, the map or lookup table is configured to assign output limit values ​​to the state of charge (SOC) and temperature of the battery 14. Such maps or lookup tables are pre-created experimentally through testing and other means, taking into account component protection and degradation suppression while the user is using the electric vehicle 100.

[0016] Figure 2 shows an example of a map for defining the output limit. However, for the sake of brevity, Figure 2 shows the map at a certain temperature Tc. Figure 2 shows two maps: the first map M11 and the second map M12. In Figure 2, Wn is the lower limit of the output of the battery 14 that can drive the electric vehicle 100 with sufficient driving force for smooth transportation. That is, the required charge level is the SOC at which the output limit value is Wn. In other words, as shown in Figure 2, LCp is the required charge level for the first map M11.

[0017] The inventors of this disclosure focused on output limiting in order to reduce the State of Charge (SOC) at the time of shipment. Output limiting, which is intended to protect components and suppress degradation, is usually designed to take into account various usage conditions by the user, including cases where the electric vehicle 100 is driven continuously for a long period of time. On the other hand, the electric vehicle 100 is driven for a short period of time until the completion of transportation. Therefore, even if the electric vehicle 100 is driven with a driving force that exceeds the default output limit to some extent during the period until the completion of transportation, the purpose of protecting components and suppressing degradation will not be impaired. Accordingly, the battery management device 101 according to this embodiment is configured to relax the output limiting until the completion of transportation of the electric vehicle 100 after shipment.

[0018] For example, the battery management device 101 is configured to switch the map that determines the output limit value from the first map M11 to the second map M12 until the transportation of the electric vehicle 100 after shipment is completed. As shown in FIG. 2, in the second map M12, compared with the first map M11, the output limit is relaxed, and even when the SOC becomes LCp, the output limit value is Wn or more. That is, the required charge rate can be reduced. Specifically, the required charge rate has changed from LCp to LCa. As a result, as shown in FIG. 1, it can be seen that even in pattern E2, the SOC during transportation can be maintained at LCa or more, which is the required charge rate. That is, the SOC at the time of shipment can be reduced from SCp to SCa. Alternatively, the battery management device 101 may be configured to relax the output limit by dynamically correcting the map that determines the output limit value. In this way, according to the battery management device 101 according to the present embodiment, it is possible to reduce the SOC at the time of shipment of the electric vehicle 100.

[0019] 2 Configuration of Electric Vehicle Hereinafter, the configuration of the electric vehicle 100 to which the battery management device 101 according to the present embodiment is applied will be described. FIG. 3 is a diagram showing an example of the configuration of the electric vehicle 100.

[0020] The electric vehicle 100 includes an electric motor (M) 2 as a driving source for traveling. The electric motor 2 is, for example, a three-phase AC motor. An inverter (INV) 16 is attached to the electric motor 2. The output shaft of the electric motor 2 is connected to the propeller shaft 5 via a speed reducer (not shown). The propeller shaft 5 is connected to a differential gear 6. The differential gear 6 is connected to the left and right drive wheels 8 by the left and right drive shafts 7. The drive wheels 8 may be front wheels or rear wheels. The inverter 16, the electric motor 2, the speed reducer, and the differential gear 6 may be integrally configured as an e-axle. In this case, the e-axle is directly connected to the drive shaft 7 without passing through the propeller shaft 5.

[0021] The inverter 16 is connected to the battery 14. The inverter 16 is, for example, a voltage-type inverter that controls the motor torque of the electric motor 2 by PWM control. The battery 14 is typically a high-voltage battery composed of multiple battery cells. Examples of battery cells include lithium-ion batteries, nickel-metal hydride batteries, solid-state batteries, etc. The battery 14 is equipped with a temperature sensor 32, a current sensor 34, and a voltage sensor 36. The temperature sensor 32 outputs a signal indicating the temperature of the battery 14. The current sensor 34 outputs a signal indicating the current value of the current flowing through each part of the battery 14. The voltage sensor 36 outputs a signal indicating the voltage value between the terminals of the battery 14 and each battery cell.

[0022] The electric vehicle 100 is equipped with various operating components 18. Examples of operating components 18 include a wiper switch, turn signal switch, door switch, multimedia control switch, horn switch, starter switch, interior light switch, parking brake operating device, steering wheel, accelerator pedal, brake pedal, shifter, etc. Each operating component 18 is provided with an operating state detection sensor 38. The operating state detection sensor 38 outputs a signal indicating the operating state of each operating component 18. For example, an operating state detection sensor 38 provided on each switch outputs a signal indicating the pressed state of each switch. Also, for example, an operating state detection sensor 38 provided on the steering wheel outputs a signal indicating the steering angle of the steering wheel. Also, for example, an operating state detection sensor 38 provided on the accelerator pedal outputs a signal indicating the accelerator opening angle.

[0023] The electric vehicle 100 is also equipped with a human-machine interface (HMI) 20. The HMI 20 presents various information to the driver through displays and sounds, and also accepts various inputs from the driver. The HMI 20 consists of a display (e.g., multi-information display, meter display, multimedia display), indicator lamps, touchscreen, switches, touchpad, speakerphone, microphone, etc. The operating component 18 may function as part of the HMI 20 for accepting various inputs.

[0024] The electric vehicle 100 is equipped with a battery management device 101 and a motor control device 200. The battery management device 101 is connected to the battery 14 and manages the operation of the battery 14. The motor control device 200 is connected to the inverter 16 and controls the output of the electric motor 2 via PWM control by the inverter 16. The battery management device 101 and the motor control device 200 are typically electronic control units (ECUs). The battery management device 101 and the motor control device 200 may each be a combination of multiple ECUs.

[0025] The battery management device 101 is configured to acquire signals from the temperature sensor 32, current sensor 34, and voltage sensor 36 provided on the battery 14. The battery management device 101 is also configured to acquire signals from the operation state detection sensor 38 and HMI 20 via an in-vehicle network such as a control area network (CAN). Based on the acquired signals, the battery management device 101 generates control signals to manage the operation of the battery 14. In particular, as part of the management of the battery 14, the battery management device 101 limits the output of the battery 14. That is, the control signals generated by the battery management device 101 include an output limit value LW related to the output limit of the battery 14. The battery management device 101 transmits the output limit value LW to the motor control device 200.

[0026] The battery management device 101 includes one or more processors 102 (hereinafter simply referred to as processor 102) and one or more storage devices 103 (hereinafter simply referred to as storage devices 103).

[0027] The processor 102 performs various processes. The processor 102 consists of, for example, a general-purpose processor, a special-purpose processor, a CPU (central processing unit), a GPU (graphics processing unit), an ASIC (application-specific integrated circuit), an FPGA (field-programmable gate array), an integrated circuit, a conventional circuit, and one or more combinations thereof. The processor 102 can also be called processing circuitry. Processing circuitry is hardware programmed to realize the functions of the battery management device 101, or hardware that performs the functions of the battery management device 101.

[0028] The storage device 103 stores various information necessary for the execution of processing by the processor 102. The storage device 103 is composed of recording media such as RAM (random access memory), ROM (read-only memory), SSD (solid state drive), HDD (hard disk drive), etc. The storage device 103 stores a computer program 104 that can be executed by the processor 102 and various data 105. The computer program 104 consists of multiple instruction codes that describe the processing to be executed by the processor 102. The computer program 104 is recorded on a computer-readable recording medium. The functions of the battery management device 101 are realized through the cooperation of the processor 102, which executes the computer program 104, and the storage device 103.

[0029] The motor control device 200 calculates the target driving force of the electric vehicle 100 in accordance with the driver's operation, based on signals from a sensor system including sensors (e.g., vehicle speed sensor, motor rotation speed sensor) not shown. Examples of signals input to the motor control device 200 from the sensor system include signals indicating the vehicle speed of the electric vehicle 100, signals indicating the operation state of the accelerator pedal, signals indicating the operation state of the brake pedal, signals indicating the rotation speed of the electric motor 2, signals indicating various states of the battery 14, etc. The motor control device 200 calculates the target driving force using, for example, a map. In this case, the map is configured to assign a target driving force to the operation state of the driving control members (e.g., accelerator opening, brake opening) and the driving state of the electric vehicle 100 (e.g., rotation speed of the electric motor 2, vehicle speed). The motor control device 200 then controls the output of the electric motor 2 to achieve the calculated target driving force.

[0030] In this embodiment, the motor control device 200 is configured to control the output of the electric motor 2, taking into account an output limit value LW obtained from the battery management device 101. That is, the motor control device 200 calculates a target driving force so that the output of the battery 14 does not exceed the output limit value LW. For example, the motor control device 200 saturates the target driving force when the output limit value LW is reached. Alternatively, for example, the motor control device 200 corrects the map that provides the target driving force according to the output limit value LW. In this way, the output limit of the battery 14 by the battery management device 101 can be achieved. Such a functional configuration of the motor control device 200 can employ known and preferred methods used to calculate the target driving force in conventional BEVs.

[0031] As described above, an electric vehicle 100 to which the battery management device 101 according to this embodiment is applied is configured. The battery management device 101, together with the sensor system, can also be called a battery management system (BMS).

[0032] 3. Functional configuration of the battery management device The functional configuration of the battery management device 101 according to this embodiment will be described below. Figure 4 is a diagram showing an example of the functional configuration of the battery management device 101. Signals from the sensor system are input to the battery management device 101. The signals input to the battery management device 101 from the sensor system include a signal indicating the temperature of the battery 14, a signal indicating the current value of the current flowing through each part of the battery 14, a signal indicating the voltage value between the terminals of the battery 14 and each battery cell, and a signal indicating the operating status of various operating members 18 of the electric vehicle 100.

[0033] The battery management device 101 includes, as functional blocks, a limit relaxation determination unit 110, a SOC calculation unit 120, and an output limit value calculation unit 130. These functional blocks are realized through the cooperation of a processor 102 that executes a computer program 104 and a storage device 103.

[0034] The limit relaxation determination unit 110 determines whether or not to relax the output limit. The limit relaxation determination unit 110 determines to relax the output limit until the transportation of the electric vehicle 100 after shipment is completed. The limit relaxation determination unit 110 also determines to revert to the default output limit after the transportation of the electric vehicle 100 is completed. The limit relaxation determination unit 110 transmits the determination result to the output limit value calculation unit 130. Furthermore, the battery management device 101 may be configured to transmit the determination result of the limit relaxation determination unit 110 to the HMI 20. In this case, the HMI 20 may be configured to notify the user by display or sound that the output limit has been relaxed while it is receiving the determination result to relax the output limit. The limit relaxation determination unit 110 can determine whether or not the transportation of the electric vehicle 100 after shipment is completed from the following viewpoints.

[0035] The first perspective concerns the charging history of the battery 14. Immediately after the electric vehicle 100 is shipped from the production plant P1, the charging history of the battery 14 is naturally in its initial state. It is assumed that the electric vehicle 100 will be charged by the dealer P2 after it is handed over to the dealer P2. In particular, it is not assumed that the electric vehicle 100 will be charged during transportation. Therefore, according to this perspective, the restriction relaxation determination unit 110 will determine that the post-shipment transportation of the electric vehicle 100 is complete upon receiving the recording of the charging history of the battery 14. Alternatively, the restriction relaxation determination unit 110 may determine that the post-shipment transportation of the electric vehicle 100 is not complete while the charging history of the battery 14 is in its initial state (e.g., no record).

[0036] The second perspective concerns specific operations on the operating members 18. At the production plant P1, the post-shipment transportation of the electric vehicle 100 is naturally not yet complete. Furthermore, workers at the production plant P1 can operate each of the operating members 18 of the electric vehicle 100 that were produced before shipment. Therefore, according to this perspective, the restriction relaxation determination unit 110 determines that the post-shipment transportation of the electric vehicle 100 is not yet complete upon receiving that a specific operation has been performed on the operating members 18. The restriction relaxation determination unit 110 can determine whether or not a specific operation has been performed on the operating members 18 based on the signal from the operation state detection sensor 38. It is desirable that the specific operation is something that would never be performed during the normal use of the electric vehicle 100. This is to prevent the user of the electric vehicle 100 from accidentally performing the specific operation. For example, the specific operation is to turn the left and right turn signals on and off alternately twice each, and then sound the horn, within a predetermined time (e.g., 10 seconds). Incidentally, at the dealer P2, the post-shipment transportation of the electric vehicle 100 is naturally complete. Therefore, the restriction relaxation determination unit 110 may determine that the post-shipment transportation of the electric vehicle 100 has been completed upon receiving that a specific operation has been performed on the operating member 18.

[0037] Figure 5 is a flowchart showing the processing flow of the process executed by the restriction relaxation determination unit 110. The processing flow shown in Figure 5 is executed repeatedly at a predetermined processing cycle.

[0038] In step S110, the limit relaxation determination unit 110 determines whether the post-shipment transportation of the electric vehicle 100 has been completed. If it determines that the post-shipment transportation has been completed (step S110; Yes), the limit relaxation determination unit 110 decides to apply the default output limit (step S120) and terminates the process. If it determines that the post-shipment transportation has not been completed (step S110; No), the limit relaxation determination unit 110 decides to relax the output limit (step S130) and terminates the process.

[0039] Refer to Figure 4 again. The SOC calculation unit 120 calculates the State of Charge (SOC) of the battery 14 based on signals from the current sensor 34 and the voltage sensor 36. The SOC calculation method in the SOC calculation unit 120 may employ any known preferred technique. The SOC calculation unit 120 transmits the calculated SOC to the output limit value calculation unit 130.

[0040] The output limit calculation unit 130 uses a map to calculate the output limit value LW for the battery 14's SOC and temperature. In particular, the output limit calculation unit 130 uses the first map M11 when it has determined that the default output limit should be applied. On the other hand, the output limit calculation unit 130 uses the second map M12 when it has determined that the output limit should be relaxed. That is, the first map M11 is a map for calculating the default output limit value LW, and the second map M12 is a map for calculating the relaxed output limit value LW (see Figure 2). The first map M11 and the second map M12 may be experimentally created in advance through testing, etc., and stored in the storage device 103 as a computer program 104 or data 105. The battery management device 101 transmits the output limit value LW calculated by the output limit calculation unit 130 to the motor control device 200.

[0041] The output limit calculation unit 130 may be configured to correct the first map M11 when it has obtained a decision result to relax the output limit, and to calculate the output limit value LW using the corrected first map M11. In this case, the output limit calculation unit 130 may be configured to estimate the internal resistance of the battery 14 based on signals from the current sensor 34 and the voltage sensor 36, and to calculate a correction value for the first map M11 according to the estimated internal resistance. The internal resistance of the battery 14 serves as an indicator of the battery 14's deterioration state. Therefore, the output limit calculation unit 130 may reduce the correction value when the internal resistance is above a predetermined value.

[0042] 4. Variation: Decision on relaxing output limits based on battery status The battery management device 101 according to this embodiment may adopt the following modified form.

[0043] In recent years, there has been a growing demand for the reuse and recycling of batteries 14. For this reason, it is conceivable that even the batteries 14 in electric vehicles 100 immediately after production may be in a somewhat deteriorated state. When such deterioration of the battery 14 has progressed to a certain extent, even a short-term relaxation of the output limit may cause significant deterioration of the battery 14. To address this issue, the limit relaxation determination unit 110 of the battery management device 101 may be configured to determine whether the state of the battery 14 is such that relaxation of the output limit is not permissible (hereinafter referred to as "unrelaxable state"). The limit relaxation determination unit 110 may also be configured to determine that the default output limit should be applied (the output limit should not be relaxed) if the battery 14 is in an unrelaxable state.

[0044] Figure 6 is a flowchart showing the processing flow of the restriction relaxation determination unit 110 that performs the modified example. The processing flow shown in Figure 6 is executed repeatedly at a predetermined processing cycle. Compared to the processing flow shown in Figure 5, the processing flow shown in Figure 6 includes additional processing related to steps S111 and S112.

[0045] In a modified example, if it is determined that post-shipment transportation is not complete (step S110; No), the process proceeds to step S111. In step S111, the limit relaxation determination unit 110 checks the state of the battery 14. For example, the limit relaxation determination unit 110 estimates the internal resistance of the battery 14 based on signals from the current sensor 34 and the voltage sensor 36. The limit relaxation determination unit 110 then determines that the state of the battery 14 is in a state where relaxation is not possible if the estimated internal resistance exceeds a threshold. Alternatively, for example, the limit relaxation determination unit 110 calculates the cumulative discharge amount based on the discharge history of the battery 14. The limit relaxation determination unit 110 then determines that the state of the battery 14 is in a state where relaxation is not possible if the calculated cumulative discharge amount exceeds a threshold.

[0046] If, as a result of the processing related to step S111, it is determined that the state of the battery 14 is in a state that cannot be relaxed (step S120; Yes), the limit relaxation determination unit 110 decides to set the output limit to the default value (step S120) and terminates the process. On the other hand, if it is determined that the state of the battery 14 is not in a state that cannot be relaxed (step S120; No), the limit relaxation determination unit 110 decides to relax the output limit (step S130) and terminates the process. [Explanation of Symbols]

[0047] 2 Electric motor 14 batteries 16 Inverters 18 Operating Member 100 Electric Vehicles 101 Battery Management Device 102 processors 103 Storage device

Claims

1. A battery management device for managing the operation of an electric vehicle battery, The system includes one or more processors that limit the output of the aforementioned battery, The one or more processors described above are: The output limit of the battery is relaxed until the transportation of the electric vehicle after shipment is completed. It is configured in such a way Battery management device.

2. A battery management device according to claim 1, The one or more processors described above are: Upon recording the charging history of the battery, it is determined that the post-shipment transportation of the electric vehicle has been completed. It is configured in such a way Battery management device.

3. A battery management device according to claim 1, The one or more processors described above are: Based on the fact that a specific operation has been performed on the operating member of the electric vehicle, it is determined that the post-shipment transportation of the electric vehicle has not been completed. It is configured in such a way Battery management device.

4. A battery management device according to claim 1, The one or more processors further include: If the battery state is such that relaxation of the output limit is not permitted, the output limit will not be relaxed. It is configured in such a way Battery management device.

5. A battery management device according to claim 4, The one or more processors described above are: The internal resistance of the aforementioned battery is estimated, When the internal resistance exceeds the threshold, it is determined that the battery is in the unrelaxable state. It is configured in such a way Battery management device.

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