Control device for electric vehicle

Abstract

The invention provides a control device of an electric vehicle. The control device of the electric vehicle has a boost mode function which is convenient to use for a driver. This electric vehicle control device is provided with: a controller that drives and controls a travel motor within a range in which the output of a battery is equal to or less than an output upper limit; and a battery controller that monitors a state of the battery. Moreover, the control mode of the controller includes a boost mode in which the output upper limit is temporarily increased based on the operation of the boost operation portion, the controller determines whether to allow the boost mode according to a quantity related to the deterioration state of the battery, and the controller controls the boost mode when the quantity related to the deterioration state of the battery is a quantity in which the boost mode is not allowed. A meter display that indicates how much change in the amount related to the deterioration state allows the supercharging mode is output to a display unit.

Description

Technical Field

[0001] The invention relates to a control device for an electric vehicle. Background Art

[0002] Reference 1 describes an electric vehicle having a first running mode in which the upper limit of the battery output is set to a standard value and a second running mode in which the upper limit of the battery output is set to a value higher than the standard value. In this electric vehicle, switching to the second running mode is performed based on a driver's request.

[0003] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2022-092106 Summary of the invention

[0004] Technical issues In an electric vehicle, the life of the battery can be extended by suppressing the upper limit of the battery output to a low value. On the other hand, by enabling the activation of a boost mode that allows a temporary large output, the driver's preference can be responded to. After the boost mode is activated once, it takes time to activate until it can be activated again. When the boost mode cannot be activated, it is preferred that the driver can understand how long it will take to activate the boost mode.

[0005] An object of the present invention is to provide a control device for an electric vehicle having a boost mode function which is easy to use for a driver.

[0006] Technical Solution The control device for an electric vehicle of the present invention is characterized in that it is mounted on an electric vehicle, wherein the electric vehicle includes a travel motor for driving drive wheels, a battery for storing travel power, a boost operation unit operable by a driver, and a display unit arranged in a cab. The control device of the electric vehicle comprises: a controller that drives and controls the travel motor within a range where the output of the battery is below an output upper limit; and a battery controller that monitors the status of the battery, The control mode of the controller includes a boost mode, in which the output upper limit is temporarily increased based on the operation of the boost operation unit. the controller determines whether to allow the boost mode based on a quantity related to a degradation state of the battery, The controller outputs a meter display to the display unit indicating how much the amount related to the degradation state changes before the supercharging mode is allowed, when the amount related to the degradation state is an amount that does not allow the supercharging mode.

[0007] Technical Effects According to the present invention, it is possible to provide a function of a supercharging mode that is convenient for the driver to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a block diagram showing an electric vehicle equipped with a control device according to an embodiment of the present invention.

[0009] Figure 2 is a flowchart showing a supercharging mode control process executed by the controller.

[0010] Figure 3A This is a graph for explaining the amount related to the battery degradation state calculated in order to determine whether the boost mode is enabled or not.

[0011] Figure 3B It is shown in Figure 3A A diagram showing an example of an image displayed on a display unit when the device is in a degraded state.

[0012] Figure 4A This is a graph for explaining the amount related to the battery degradation state calculated in order to determine whether the boost mode is enabled or not.

[0013] Figure 4B It is shown in Figure 4A A diagram showing an example of an image displayed on a display unit when the device is in a degraded state.

[0014] Explanation of symbols 1. Electric vehicles 2: Driving wheel 3: Driving motor 4: Battery 5: Converter 6: Driving operation unit 7: Booster operation unit 8: Display unit 9: Braking device 40: Control device 41: Controller 42: Battery Controller 44: Sensor 82: Instrument display 84: Information display DETAILED DESCRIPTION

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0016] Figure 1 This is a block diagram showing an electric vehicle equipped with a control device according to an embodiment of the present invention.

[0017] The electric vehicle 1 includes a driving wheel 2, a traveling motor 3 driving the driving wheel 2, a battery 4 storing electric power for traveling, a converter 5 converting electric power between the battery 4 and the traveling motor 3, a traveling operation unit 6 capable of performing operations for traveling, a boost operation unit 7 operable by a driver, a display unit 8 disposed in a cab, a brake device 9 that exerts a braking effect by hydraulic pressure or the like, and a control device 40 of the present embodiment. The control device 40 controls the electric vehicle 1.

[0018] The driving operation unit 6 includes a steering operation unit 6a such as a steering wheel, an acceleration operation unit 6b such as an accelerator pedal, and a brake operation unit 6c such as a brake pedal. The driving operation unit 6 may be operated by the driver or by the automatic driving system.

[0019] The boost operation unit 7 is an operation unit for starting the boost mode. The boost operation unit 7 is an operation unit on a button, a paddle, a touch panel, etc., but in addition, various forms of operation units may be used. Alternatively, the boost operation unit 7 may also use the driving operation unit 6 such as the acceleration operation unit 6b, and the operation of the driving operation unit 6 in a predetermined manner may be applied as the operation of the boost operation unit 7. For example, various types of operations such as the operation of making the pedaling speed Z or above when the pedaling amount of the accelerator pedal is within the range Y may also be applied as the operation of starting the boost mode.

[0020] The travel motor 3 is an electric motor. The battery 4 supplies electric power for driving the travel motor 3. The battery 4 is, for example, a lithium-ion secondary battery, a nickel-metal hydride secondary battery, etc., but the type is not particularly limited. The battery 4 stores electric power supplied from an external power source and regenerative electric power transmitted from the travel motor 3. The converter 5 transmits the electric power of the battery 4 to the travel motor 3 to cause the travel motor 3 to perform power operation, and transmits the regenerative electric power of the travel motor 3 to the battery 4 to cause the travel motor 3 to perform regenerative operation.

[0021] The control device 40 includes: a controller 41 that controls the driving and the user interface via the display unit 8; and a battery controller 42 that manages the battery 4. The controller 41 and the battery controller 42 are microcomputers that operate according to control programs. The controller 41 and the battery controller 42 operate in coordination by communicating with each other. The controller 41 may also be called a vehicle controller.

[0022] The control device 40 further includes a sensor 44 for measuring the current, voltage, and temperature of the battery 4. The sensor 44 transmits a measurement signal to the battery controller 42.

[0023] It should be noted that the microcomputer included in the control device 40 does not need to be divided into the controller 41 and the battery controller 42. The controller 41 and the battery controller 42 may be integrated into one microcomputer. Alternatively, the control device 40 may also include three or more microcomputers, and the functions of the controller 41 and the battery controller 42 are realized by their coordinated actions.

[0024] The controller 41 receives operation signals from the travel operation unit 6 and the boost operation unit 7 , and controls the converter 5 and the brake device 9 according to the operation and the state of the battery 4 , thereby controlling the driving force and the braking force of the electric vehicle 1 .

[0025] The battery controller 42 measures or estimates the state of the battery 4 based on the measurement signal of the sensor 44 and monitors the state of the battery 4. The state of the battery 4 includes the charge remaining amount (SOC: State Of Charge, etc.) and the degree of degradation (SOH: State of Health, etc.).

[0026] In detail, the battery controller 42 calculates the SOC at each time point by accumulating the current value at each time point or converting it according to the voltage value. In addition, the battery controller 42 calculates the full charge capacity of the battery 4 based on the accumulation of the normal current and the detection of the full charge state and the predetermined discharge state based on the measured voltage, and calculates the SOH by comparing it with the initial full charge capacity. SOH refers to the ratio of the full charge capacity at the time of degradation when the initial full charge capacity is set to 100%. In addition, the battery controller 42 can also store a calculation formula or a data table representing the relationship between various state quantities of the battery 4 and the estimated value of the SOH in the storage unit 42a, and estimate the SOH based on the measured values ​​of each state quantity and the calculation formula or the data table. The state quantity of the battery 4 related to the SOH includes the charge and discharge speed (also called C rate) when driving, the temperature of the battery 4, the range of the SOC that has been charged and discharged, etc. The state quantity of the battery 4 related to the SOH includes the SOC and the temperature of the battery 4 when parking.

[0027] It should be noted that the degree of degradation of the battery 4 managed by the battery controller 42 is not limited to the SOH represented by the charge capacity, and various degrees of degradation such as the degree of degradation represented by the internal resistance, charge and discharge efficiency, or maximum current may be applied.

[0028] The battery controller 42 also manages the chargeable power Win and the dischargeable power Wout of the battery 4. The chargeable power Win and the dischargeable power Wout change according to the state quantities of the battery 4 such as the remaining charge amount and the temperature. The battery controller 42 stores a data table indicating the correspondence between the state quantity of the battery 4 and the chargeable power Win and the dischargeable power Wout, and obtains the above-mentioned chargeable power based on the data table.

[0029] The controller 41 controls the power operation of the travel motor 3 via communication with the battery controller 42 so that power exceeding the dischargeable power Wout is not discharged from the battery 4. The controller 41 controls the regenerative operation of the travel motor 3 via communication with the battery controller 42 so that power exceeding the chargeable power Win is not supplied to the battery 4.

[0030] <Normal Mode and Boost Mode> The controller 41 can switch the control mode of the electric vehicle 1 between the normal mode and the boost mode. The normal mode is a control mode in which the driving control of the travel motor 3 is performed below the normal output upper limit (i.e., the output upper limit of the battery 4). The boost mode is a control mode in which the output upper limit of the travel motor 3 (i.e., the output upper limit of the battery 4) is temporarily (for example, 3 seconds to 8 minutes, etc.) increased. The output upper limit in the normal mode is a value that is preset in such a way that the degradation of the battery 4 does not develop significantly. The output upper limit in the boost mode is a value that is preset in such a way that the degradation of the battery 4 develops faster than the degradation of the battery 4 in the normal mode, but the normal operation of the components of the travel system (the travel motor 3, the battery 4, and the converter 5, etc.) is ensured by limiting the output to a temporary output.

[0031] It should be noted that the boost mode may also be a control mode in which the driving force can be output to a temporarily increased output upper limit when the dischargeable power Wout of the battery 4 is high. In addition, the boost mode may also be a control mode in which the dischargeable power Wout obtained according to the state of the battery 4 is temporarily increased (for example, increased to 120%) when the battery 4 is in various states.

[0032] <Expected change in the degree of degradation in single boost mode> When the boost mode is activated, the degree of degradation of the battery 4 generally progresses significantly compared to the case of normal mode driving. However, even when the boost mode is activated, the degradation of the battery 4 does not progress rapidly unless the driver performs a large acceleration operation. In addition, even when the same acceleration operation is performed, the amount of progression of the degradation state varies depending on environmental conditions such as ambient temperature and the state of the battery 4 such as SOC and temperature.

[0033] The controller 41 holds in advance data of the expected change in the degree of degradation of the battery 4 when a large output is performed in the boost mode. The expected change can be the change when the degradation state develops most rapidly. That is, it is the change in the degradation state when the environmental conditions and the state of the battery 4 that cause the degradation state to develop most rapidly due to the maximum acceleration operation. By adopting such an expected change, the change range of the degradation degree from 0% to 100% of the instrument display 82 described later can be fixed. Therefore, the driver can easily remember the change speed of the instrument display 82, which can help to make the instrument display 82 easy to understand.

[0034] It should be noted that the expected change amount of the degree of degradation maintained by the controller 41 is not limited to the above example, and may be, for example, the change amount of the degree of degradation when driving operation in an average boost mode of 90%, 80% or the like of the maximum output is performed. In addition, a data table or calculation formula of the expected change amount corresponding to the environmental conditions and the state of the battery 4 may be provided to the controller 41 in advance. Furthermore, the controller 41 may also calculate the expected change amount of the degree of degradation based on the above data table or calculation formula, the environmental conditions and the state of the battery 4.

[0035] <Assumed Degradation of Battery 4> In the electric vehicle 1, the assumed degradation degree of the battery 4 is predetermined. The assumed degradation degree refers to the degradation degree planned in advance, which is the degradation degree planned by the manufacturer or dealer. The battery 4 deteriorates with use, and even if there is no charge or discharge, the degradation will be aggravated by the passage of time. Therefore, the assumed degradation degree can also be planned in a manner determined according to the driving distance and total time of the electric vehicle 1. Alternatively, the assumed degradation degree can also be planned in a manner determined according to the driving distance of the electric vehicle 1 or according to the total time of the electric vehicle 1. Data for obtaining the assumed degradation degree is stored in the storage unit 41a of the controller 41. The data is a calculation formula or a data table for calculating the degradation degree according to the above plan. The controller 41 can obtain the assumed degradation degree of the battery 4 based on the total time of the electric vehicle 1, the driving distance, or both, and the above data. By setting the assumed degradation degree in this way, the user can grasp the period of continuous use of the battery 4 and the driving distance.

[0036] <Boost mode control processing> Figure 2 : is a flowchart showing the control process of the supercharging mode executed by the controller.

[0037] The controller 41 repeatedly performs the control process of the boost mode during the operation of the electric vehicle 1. In the control process, first, the controller 41 obtains the degradation degree of the battery 4 at that time from the battery controller 42 (step S1). The battery controller 42 measures or estimates the degradation degree of the battery 4 at each time in the above manner.

[0038] Next, the controller 41 determines whether the boost mode is possible based on the quantity related to the degradation state of the battery 4 (step S2). The quantity related to the degradation state refers to the quantity that can absolutely or relatively represent the degradation state of the battery 4, such as the degradation degree of the battery 4, the difference between the degradation degree and the assumed degradation degree, and the comparison between the difference and the expected change in the degradation degree caused by the single boost mode. By judging based on the quantity related to the degradation state, the following control can be performed: the boost mode is not allowed when the degradation of the battery 4 is aggravated, and the boost mode is allowed when the degradation of the battery 4 does not develop rapidly. Through this control, it is possible to achieve control of the boost mode that appropriately takes into account both the life of the battery 4 and the driver's preference.

[0039] Specifically, in step S2, the controller 41 determines whether the boost mode is possible based on the difference between the degradation degree of the battery 4 at that time and the assumed degradation degree previously assumed for the electric vehicle 1. By such control, it is possible to prevent the degradation degree of the battery 4 from greatly deviating from the assumed degradation degree due to the boost mode.

[0040] More specifically, in step S2, the controller 41 determines whether the boost mode can be enabled by comparing the degradation degree α at that time point, the assumed degradation degree β, and the expected change γ of the degradation degree caused by the boost mode. For example, α+γ≤β is set as a permissible condition. Based on such a condition, the boost mode can be enabled in a manner that the degradation degree of the battery 4 does not exceed the assumed degradation degree.

[0041] If the result of step S2 is permission, the controller 41 determines whether a shift operation to the supercharging mode has been performed (step S3 ). If no operation has been performed, the controller 41 repeats the process of step S3 until the operation has been performed.

[0042] On the other hand, if an operation is performed in step S3, the controller 41 switches the control mode to the supercharging mode and performs temporary supercharging mode control (step S4). Then, if the supercharging mode is completed and returns to the normal mode, the controller 41 returns the process to step S1.

[0043] On the other hand, if it is determined that the boost mode is not permitted in the determination of whether or not the boost mode is permitted, the controller 41 outputs a display 80 including a meter display 82 to the display unit 8, the meter display 82 indicating how much the quantity related to the deterioration state of the battery 4 changes before the boost mode is permitted (step S5). Then, the controller 41 returns the process to step S1.

[0044] While the boost mode is not permitted, the controller 41 repeatedly performs the loop process of steps S1 , S2 , and S5 , thereby realizing a meter display 82 reflecting the degree of degradation of the battery 4 at each time point.

[0045] <Instrument display> Figure 3A and Figure 4A This is a graph for explaining the amount related to the battery degradation state calculated in order to determine whether the boost mode is enabled or not. Figure 3B and Figure 4B Shown respectively in Figure 3A and Figure 4A An example of an image displayed on the display unit when the degradation state of.

[0046] like Figure 3B and Figure 4B As shown, the display 80 output in step S5 includes a meter display 82 showing how long it will take to start the boost mode. The display 80 may also include a title display 81 and a display 83 of information. Figure 3B and Figure 4B As shown, the meter display 82 is a display that indicates the level by the number of lit display grids sg among the plurality of display grids sg. The meter display 82 may also be a display that indicates the level by a numerical value such as a percentage.

[0047] Furthermore, in the display 80, when the transition to the supercharging mode is not permitted, Figure 3B As shown, the information display 84 showing the driving method for shifting to the supercharging mode earlier may be included. The information display 84 can be realized by pre-storing various information showing the driving method for slowing down the aggravation of the degree of degradation in the controller 41, and the controller 41 selecting and outputting appropriate information from the information.

[0048] like Figure 3A and Figure 4A As shown in the graph of , the meter quantity indicated by the meter display 82 indicates the ratio of the degradation margin δ at that time point to the expected change amount γ of the degradation degree in the single supercharging mode. The degradation margin δ is the quantity obtained by subtracting the degradation degree α at that time point from the assumed degradation degree β at that time point.

[0049] According to such display 80, during normal mode driving, as the degradation margin δ increases, the level display of the instrument display 82 advances. Moreover, the driver can understand how long it will take for the degradation margin δ to reach the expected change amount γ of the degradation degree at a time, that is, how long it will take for the boost mode to be activated. Furthermore, at this time, the driver can know the driving operation for quickly shifting to the boost mode through the information display 84. And, as Figure 4B As shown, the meter display 82 becomes 100%, whereby the driver can understand that the supercharging mode is ready to start.

[0050] <Conditions for enabling the boost mode and another example of the instrument display> It should be noted that the conditions for allowing the boost mode are not limited to the above example. For example, a predetermined allowable error ε may be added, and the controller 41 sets α+γ≤β+ε as an allowable condition. The allowable error ε may be a positive value or a negative value. According to such conditions, the boost mode can be started in a manner such that the degree of degradation α of the battery 4 does not increase relative to the assumed degree of degradation β exceeding the range of the error ε. In this case, β+ε-α is used as the instrument object quantity, and the ratio of the instrument object quantity to the expected change γ of the single boost mode is indicated by the instrument display 82. Through such allowable conditions and displays, the driver can also grasp the boost mode in the same way as in the above case.

[0051] In addition, the controller 41 may also set α≤β as a condition for allowing the boost mode. According to such a condition, the boost mode can be started within the range of the expected change amount γ of the degradation degree α of the battery 4 relative to the assumed degradation degree β not exceeding the single amount of degradation degree. In this case, β-α+γ is used as the instrument object quantity, and the ratio of the instrument object quantity to the expected change amount γ of the single boost mode is indicated by the instrument display 82. Through such a permitted condition and display, the driver can also grasp the boost mode in the same way as in the above case.

[0052] In the above example, the ratio of the meter target amount to the expected change amount γ in the single boost mode is indicated by the meter display 82, but the expected change amount γ may be replaced by a constant γ2 of the same degree. If the constant γ2 is an appropriate value, the meter display indicating the ratio of the meter target amount to the constant γ2 can help the driver understand how long the permission is left when the boost mode is not permitted.

[0053] The program of the control process of the boost mode is stored in a non-transitory computer readable medium such as the storage unit 41a of the controller 41. The controller 41 may also be configured to read a program stored in a portable non-transitory recording medium and execute the program. The portable non-transitory storage medium may store the program of the control process of the boost mode.

[0054] The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. For example, in the above-described embodiments, an example in which the controller 41 calculates the assumed degradation degree is shown, but a configuration in which the battery controller 42 calculates the assumed degradation degree may also be applied. In addition, in the above-described embodiments, a configuration in which the controller 41 maintains or calculates the expected amount of change in the degree of degradation based on the boost mode is shown, but a configuration in which the battery controller 42 maintains or calculates the expected amount of change may also be applied. In addition, in the above-described embodiments, an electric vehicle 1 without an internal combustion engine is shown, but the electric vehicle may also have an internal combustion engine. In addition, the details shown in the embodiments may be appropriately changed without departing from the gist of the invention.

[0055] Industrial Applicability The present invention can be used in a control device for an electric vehicle.

Claims

1. A control device for an electric vehicle, It is characterized in that Installed in electric vehicles, The electric vehicle includes a travel motor for driving driving wheels, a battery for storing power for travel, a boost operation unit operable by a driver, and a display unit disposed in a cab. The control device of the electric vehicle comprises: a controller that drives and controls the travel motor within a range where the output of the battery is below an output upper limit; and a battery controller that monitors the status of the battery, The control mode of the controller includes a boost mode, in which the output upper limit is temporarily increased based on the operation of the boost operation unit. the controller determines whether to allow the boost mode based on a quantity related to a degradation state of the battery, The controller outputs a meter display to the display unit indicating how much the amount related to the degradation state changes before the supercharging mode is allowed, when the amount related to the degradation state is an amount that does not allow the supercharging mode.

2. The control device for an electric vehicle according to claim 1, It is characterized in that The quantity related to the degradation state is a difference between a pre-planned assumed degradation degree and a degradation degree of the battery estimated by the battery controller.

3. The control device for an electric vehicle according to claim 1, It is characterized in that The controller further outputs to the display unit an information display showing a driving method for enabling a faster transition to the supercharging mode.

4. The control device for an electric vehicle according to claim 2, It is characterized in that The control device for an electric vehicle includes a storage unit storing data for obtaining the assumed degree of degradation. The data shows the relationship between the battery's age, travel distance, or both, and a projected degree of degradation.

5. The control device for an electric vehicle according to claim 2, Features: The controller determines whether to allow the boost mode based on a comparison between a difference between the assumed degradation degree and the degradation degree of the battery estimated by the battery controller and an expected change in the degradation degree imposed on the battery in a single boost mode.

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