Vehicles with electric motors and their driving control methods

Abstract

This invention relates to a vehicle with an electric motor and a driving control method thereof. According to one embodiment, the driving control method for an electric vehicle using an electric motor as a power source includes determining whether a variable control function is accessible. The variable control function includes a function that variably controls the coasting torque level using regenerative braking force. When it is determined that the variable control function is accessible, control corresponding to the determination of accessibility is executed; when it is determined that the variable control function is inaccessible, the reason for inaccessibility is determined; and control corresponding to the reason for inaccessibility is determined when the variable control function is inaccessible is executed.

Description

Technical Field

[0001] This invention relates to a vehicle with an electric motor and a method for controlling its driving. Background Technology

[0002] In dictionary terms, coasting refers to continuing to move using the vehicle's inertia without outputting driving force. Typically, coasting refers to driving a vehicle without operating the accelerator pedal (APS) or brake pedal (BPS).

[0003] The torque applied to the drive shaft during coasting is called coasting torque. In typical internal combustion engine vehicles, even without pedal operation, the engine's idle torque is transmitted to the drive shaft via the torque converter and transmission. This torque is called creep torque.

[0004] During coasting, the creep torque is transmitted to the drive shaft via the engine, and the driving load due to vehicle speed is applied in the opposite direction to the creep torque. The sum of the creep torque and the driving torque constitutes the coasting torque. (See reference...) Figure 1 Describes the coasting torque.

[0005] Figure 1 This is a graph illustrating an example of the relationship between coasting torque and vehicle speed when a typical vehicle is coasting.

[0006] Reference Figure 1 At low vehicle speeds, the transmission is generally in a low gear. Therefore, with the speed of the transmission's input gears lower than the engine's idle RPM, the engine's idle torque is transmitted, causing the vehicle to creep. Conversely, at high vehicle speeds, the transmission is in a relatively high gear, so the speed of the transmission's input gears is higher than the engine's idle RPM. In this situation, the drag caused by cutting off the engine's fuel supply (fuel cut-off) is transmitted, thus generating coasting torque.

[0007] Due to increasing environmental concerns, electric vehicles that use electric motors as a drive source have been developed, such as hybrid electric vehicles (HEVs) or electric vehicles (EVs).

[0008] Electric vehicles do not have an engine, or the engine in an electric vehicle is not always running. Therefore, there is no creep torque caused by an engine. However, typically, to achieve the characteristics of a conventional internal combustion engine, control is performed to generate creep torque via a drive motor. Therefore, in vehicles equipped with electric motors, such as... Figure 1As shown, at low speeds, the simulation depicts the positive torque generated by the driving force of the internal combustion engine at idle and the torque multiplication effect of the torque converter. Furthermore, at high speeds, the simulation depicts the reverse torque generated by the resistance of the engine due to the cut-off fuel supply. The region simulating the positive torque is called the creep region, and the region simulating the reverse torque is called the coasting region. In this case, the reverse torque can be implemented as regenerative braking.

[0009] In electric vehicles, during braking, the motor and hydraulic friction brake work together as a generator. Therefore, the vehicle's kinetic energy is converted into electrical energy, thus producing braking. This type of braking is called regenerative braking.

[0010] In electric vehicles, the amount of regenerative braking, or coasting level, is adjusted via a device (e.g., a paddle shifter). This provides a feature that enhances driving enjoyment and improves fuel efficiency on real-world roads. (See reference...) Figure 2 Describe this feature.

[0011] Figure 2 It is a graph illustrating the general concept of gliding levels.

[0012] Reference Figure 2 It is shown by five different sliding torques. Figure 1 The diagram illustrates the relationship between vehicle speed and the total torque applied to the axle. Specifically, each pull of the paddle shifter to the negative ("-") side increases the regenerative braking by one level, thus increasing vehicle deceleration. Each pull of the positive ("+") side decreases the regenerative braking by one level, thus decreasing vehicle deceleration. Therefore, in a vehicle, the higher the coasting level and the lower the vehicle speed, the greater the deceleration due to regenerative braking.

[0013] However, in electric vehicles, regenerative braking is not possible when the battery or motor is at high temperatures due to high-speed or high-load driving, or when the battery's state of charge (SOC) is greater than or equal to a predetermined value. Therefore, although the driver may wish to activate the coasting level control function, it cannot be accessed. Summary of the Invention

[0014] This invention relates to an electric vehicle with an electric motor and a method for controlling its driving. Specific embodiments relate to an electric vehicle and a method for controlling the driving of the electric vehicle that can expand the range of possibilities for performing functions that control regenerative braking levels.

[0015] Embodiments of the present invention provide an electric vehicle and a method for controlling the driving of an electric vehicle that can expand the range of possibilities for entering coasting level control functions.

[0016] Another embodiment of the present invention aims to provide an electric vehicle and a driving control method for setting conditions for entering the coasting level control function when the driver may perform the coasting level control function.

[0017] This invention is not limited to the technical embodiments described above. Other technical embodiments will be understood by those skilled in the art through the following description.

[0018] According to an embodiment of the present invention, a driving control method for an electric vehicle using an electric motor as a power source is provided. The method includes determining the possibility of entering a variable control function, the variable control function including a function that variably controls the coasting torque level using regenerative braking force; when it is determined that the variable control function cannot be entered, determining the reason why the variable control function cannot be entered; and performing control to resolve the reason why the variable control function cannot be entered in a manner corresponding to the possibility of entering the variable control function and the reason why the variable control function cannot be entered.

[0019] According to another embodiment of the present invention, an electric vehicle is provided including an electric motor and a control unit, wherein the control unit includes a judgment unit that determines the likelihood of entering a variable control function, the variable control function including a function of variably controlling the coasting torque level using regenerative braking force, and when it is determined that the variable control function cannot be entered, determines the reason why the variable control function cannot be entered; and a controller that performs control to resolve the reason why the variable control function cannot be entered in a manner corresponding to the likelihood of entering the variable control function and the reason why the variable control function cannot be entered.

[0020] An electric vehicle configured as described above according to at least one embodiment of the present invention can expand the range of possibilities for accessing coasting level control functions.

[0021] In particular, by predicting the likelihood of a driver executing coasting level control functions and then taking steps to address the reasons why coasting level control functions are inaccessible, the range of possibilities for accessing coasting level control functions can be expanded.

[0022] The embodiments of the present invention are not limited to those described above. Other embodiments will be apparent to those skilled in the art from the following description. Attached Figure Description

[0023] The arrangement and embodiments can be described in detail with reference to the following figures, wherein the same reference numerals refer to the same elements, and wherein:

[0024] Figure 1 This is a graph illustrating an example of the relationship between coasting torque and vehicle speed when coasting is performed in a typical vehicle.

[0025] Figure 2 It is a graph illustrating the general concept of gliding levels;

[0026] Figure 3 It is a graph illustrating the control process according to an embodiment of the present invention;

[0027] Figure 4 This is a diagram illustrating an example configuration of a controller according to an embodiment of the present invention;

[0028] Figure 5 This is a view illustrating an example of notification information accessible through a representation function according to an embodiment of the present invention; and

[0029] Figure 6 This is a flowchart illustrating an example of a vehicle driving control method according to an embodiment of the present invention. Detailed Implementation

[0030] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can practice them without excessive experimentation. The invention can be embodied in various different forms and is not limited to the embodiments described below. Unnecessary illustrations have been omitted from the drawings to clearly describe the invention, and the same constituent elements are given the same reference numerals throughout the specification.

[0031] Unless otherwise stated, the phrase "includes constituent elements" as used throughout the specification means that any other constituent elements may be further included, rather than excluding any other constituent elements. Furthermore, constituent elements given the same reference numerals throughout the specification are identical.

[0032] According to an embodiment of the present invention, when a function is used to variably control the coasting torque level by operating a predetermined device in a vehicle using a variable regenerative braking amount based on vehicle speed, if the function is inaccessible, the driver can take measures to resolve the reason for the inaccessibility of the function by considering the possibility of performing the function, thereby expanding the range of possibilities for accessing the function.

[0033] In the following description, for ease of description, the predetermined device for setting the coasting torque level in a vehicle is assumed to be a paddle shifter selected for illustrative purposes, but it is not necessarily limited to this. It will be apparent to those skilled in the art that various forms of operating devices, such as dials, push-buttons, and switches, can be used instead of a paddle shifter. Furthermore, for convenience, the function described above for controlling the coasting torque level is referred to as "coasting level variable control function," or, assuming the paddle shifter is used for the function of controlling the coasting torque level, the function is referred to as "paddle regenerative control." Additionally, electric vehicles to which embodiments of the present invention are applied may include hybrid electric vehicles (HEVs), electric vehicles (EVs), and fuel cell electric vehicles (FCEVs). Embodiments of the present invention can be applied to any type of electric vehicle capable of using a motor as its drive source and controlling regenerative braking torque.

[0034] Figure 3 This is a graph illustrating the control process according to an embodiment of the present invention.

[0035] Figure 3 The upper part of the graph illustrates the problems that typically occur during paddle regeneration control. Figure 3 The lower part of the graph illustrates the control process for expanding the range of possibilities for entering paddle regeneration control according to an embodiment of the present invention. Figure 3 In the two graphs shown, the horizontal axis of each graph represents time, and the vertical axis of each graph represents battery temperature. However, the vertical axis could represent motor temperature or battery SOC instead of battery temperature.

[0036] First, refer to Figure 3 The upper graph shows that when the battery temperature drops below the "on" reference, the driver can engage paddle regeneration control by operating the paddle shifter. Subsequently, when the battery temperature rises to the "off" reference due to motor operation or regenerative braking, the paddle regeneration control deactivates. Generally, electric vehicles do not perform separate battery cooling operations. Therefore, even if the driver later attempts to operate the paddle shifter again, paddle regeneration control cannot be activated.

[0037] According to an embodiment of the present invention, when the paddle regeneration control is not accessible, for example, Figure 3As shown in the lower part of the graph, when the battery temperature rises to the "off" reference, it is determined whether paddle regeneration control can be executed. When the determination result meets the preset conditions, active battery cooling control is executed to lower the battery temperature below the "on" reference. Therefore, when the driver requests paddle regeneration control, it can be entered immediately. Thus, the range of possibilities for entering paddle regeneration control can be expanded.

[0038] Figure 4 This is a diagram illustrating an example configuration of a controller according to an embodiment of the present invention.

[0039] Reference Figure 4 According to an embodiment of the present invention, a control unit 100 for performing control to expand the range of possibilities for entering paddle regeneration control may include a judgment unit 110 and a controller 120.

[0040] In addition, the various pieces of information input to the control unit 100 may include information about whether the vehicle is ready to drive (e.g., HEV ready, EV ready, etc., corresponding to ignition (IG) on in internal combustion engine vehicles), information about whether paddle regeneration control can be executed, requests to enter paddle regeneration control, information about forward deceleration events (traffic congestion, turning lanes, speed cameras, etc.), and reasons why paddle regeneration control cannot be entered. Reasons why paddle regeneration control cannot be entered may include, for example, battery overcharging, or excessively high motor or battery temperature, but are not limited to these.

[0041] In addition, the multiple pieces of information output by the control unit 100 may include information for operating point control, information for limiting regenerative braking through the motor, information for battery charging and discharging, etc.

[0042] The control unit 100 of an electric vehicle (EV) can be implemented as, for example, a vehicle control unit (VCU), but is not limited thereto. The control unit 100 of a hybrid electric vehicle (HEV) can be implemented as, for example, a hybrid control unit (HCU), but is not limited thereto. As another implementation example, the control unit 100 can be a control unit separately from the VCU or HCU.

[0043] Regarding the source of input information, information such as whether the vehicle is ready to drive and whether paddle regeneration control can be executed can be determined / retained by the HCU itself, and information about deceleration events ahead can be obtained from the navigation system. Additionally, the reasons why paddle regeneration control cannot be initiated can be obtained from the battery control unit (e.g., battery management system, BMS) and the motor control unit (MCU).

[0044] In addition, various output information can be transmitted to the advanced control unit that controls the powertrain, such as the HCU or VCU.

[0045] The term "control unit," including units like the motor control unit (MCU) and hybrid power control unit (HCU), is broadly used to refer only to controllers that control specific functions of a vehicle and therefore does not represent a general-purpose functional unit. For example, each control unit may include a communication interface device, memory, and one or more processors to perform the functional control assigned to it. The communication interface communicates with another control unit, such as sensors. The operating system, logic command language, input information, output information, etc., are stored in the memory. One or more processors perform the judgments, calculations, determinations, etc., required for functional control.

[0046] The functions of the decision unit 110 and the controller 120 will be described below.

[0047] The judgment unit 110 may include an entry judgment unit 111, an execution judgment unit 112, and a cause judgment unit 113.

[0048] The judgment unit 111 determines whether the paddle regeneration control can be accessed. More specifically, in most cases, in electric vehicles, the paddle regeneration control cannot be accessed when the battery is overcharged or under excessively high temperature conditions. When the battery is overcharged, the high-voltage battery cannot be further charged via the paddle regeneration control. An excessively high temperature condition occurs when the electric vehicle's powertrain electric (PE) components are overused due to high-speed / high-load driving, causing at least one of the motor, battery, and inverter to rise above a predetermined temperature value.

[0049] The execution judgment unit 112 can utilize multiple control levels to determine the ultimate probability of executing paddle shifter regeneration control. The multiple control levels are the sum of the levels set. For each event related to the probability of entering paddle shifter regeneration control, the control level increases progressively. For example, if two events are related to the probability of entering paddle shifter regeneration control, the probability of entering paddle shifter regeneration control can be set to level 0, level 1, or level 2. Specifically, if the driver attempts to enter paddle shifter regeneration control by operating the paddle shifter lever, but paddle shifter regeneration control is not accessible, the driver is likely to attempt to enter paddle shifter regeneration control again within a short period. In this case, the execution judgment unit 112 increases the control level by one level. Additionally, if the driver is alerted by navigation traffic information about an upcoming traffic congestion or deceleration event (turn, camera, IC, etc.), the driver is likely to attempt to enter paddle shifter regeneration control again. In this case, the execution judgment unit 112 can also increase the control level by one level.

[0050] The cause determination unit 113 can determine whether the inability to access the paddle regeneration control is due to battery overcharging or excessive temperature of the PE component, such as the battery, inverter, or motor.

[0051] The judgment unit 110 can send the level of entering the paddle regeneration control determined by the execution judgment unit 112 and the reason why the paddle regeneration control cannot be entered determined by the reason judgment unit 113 to the controller 120.

[0052] The controller 120 may include a discharge control unit 121, a PE cooling control unit 122, and an entry possibility notification unit 123.

[0053] In cases where battery overcharging and PE module overheating prevent the regeneration control from being initiated, the controller 120 can first perform cooling control of the battery, inverter, motor, etc., through the PE cooling control unit 122, and then perform SOC discharge control through the discharge control unit 121. This is because the PE module needs to be cooled before discharge control.

[0054] In cases where battery overcharging prevents paddle regeneration control from being activated, the discharge control unit 121 can perform SOC discharge control. For example, in a (P)HEV, at control level 1, a low SOC is achieved by executing operating point control, which increases the motor's output torque above the engine's output torque when generating the torque required by the driver. Furthermore, at control level 2, as a method to limit the amount of regenerative braking generated by the motor during braking, a high SOC is suppressed by preventing further charging of the battery.

[0055] In cases where the regenerative braking control cannot be initiated due to excessively high temperatures in the battery, inverter, motor, etc., the PE cooling control unit 122 performs cooling control on the PE module. For example, at control level 1, the charging / discharging of the battery is limited to control and reduce the temperature of the PE module. Furthermore, at control level 2, the amount of regenerative braking generated by the motor during braking is limited to prevent the temperature of the PE module from further increasing due to motor charging.

[0056] When the paddle regeneration control becomes accessible via discharge control by discharge control unit 121 or cooling control by PE cooling control unit 122, notification unit 123 can control a predetermined output unit to notify the driver that paddle regeneration control is now accessible. (Refer to...) Figure 5 Describe the notification.

[0057] Figure 5 This is a view illustrating an example of notification information accessible through a representation function according to an embodiment of the present invention.

[0058] Reference Figure 5 The information indicating that the paddle regeneration control has become accessible can be output on the display area 410 of the instrument cluster 400, which is capable of displaying a graphic. However, the graphic display is provided here for illustrative purposes, so the notification information can be output in the form of a warning light instead of a graphic display. Alternatively, the notification information displayed on the display area 410 of the instrument cluster 400 can, of course, be displayed on the display of a head-up display (HUD) or a head unit, which is a predetermined output unit.

[0059] The control methods described above are based on Figure 6 The flowchart is a summary of the process.

[0060] Figure 6 This is a flowchart illustrating an example of a vehicle driving control method according to an embodiment of the present invention. Figure 6 For convenience, the paddle regeneration control function will be referred to as "function".

[0061] Reference Figure 6 If the vehicle is deemed drivable (S601 indicates "Yes"), the judgment unit 111 determines whether the paddle regeneration control function is accessible (S602). If the paddle regeneration control function is accessible (S602 indicates "Yes"), the paddle regeneration control function is activated. If the paddle regeneration control function is inaccessible (S602 indicates "No"), the judgment unit 112 determines the control level.

[0062] Specifically, the initial control level is level 0 (S603). If the driver attempts to enter the paddle regeneration control function by operating a unit such as a paddle shifter ("Yes" in S604), the control level is raised by one level (S605).

[0063] In addition, if a deceleration event occurs within a predetermined distance ahead ("Yes" in S606), the control level can be raised by one level (S607).

[0064] For example, if no deceleration event occurs ahead but the driver attempts to engage the paddle regeneration control function, the control level is level 1. If the driver does not attempt to engage the paddle regeneration control function but a deceleration event occurs ahead, the control level is also level 1. If the driver attempts to engage the paddle regeneration control function and a deceleration event also occurs ahead, the control level is level 2. Of course, if no deceleration event occurs and the driver does not attempt to engage the paddle regeneration control, the control level is level 0. When the control level is set to "0", the controller 120 may neither perform discharge control nor PE component cooling control.

[0065] The cause determination unit 113 can determine the reason why the paddle regeneration control cannot be entered. If it is determined that the PE component temperature is too high, causing the paddle regeneration control to be inaccessible ("Yes" in S608), the cause determination unit 113 can execute cooling control of the PE component corresponding to the control level. For example, if the control level is 1 ("Yes" in S609), the PE cooling control unit 122 can limit the power of battery charging / discharging (S610). If the control level is 2 ("Yes" in S611), the PE cooling control unit 122 can limit the regenerative braking of the motor (S612). According to another embodiment of the present invention, step S609 can be changed to "Is the control level 1 or higher?". In this case, when the control level is 2, both battery charging / discharging and motor regenerative braking can be limited simultaneously.

[0066] Furthermore, if the cause determination unit 113 determines that the battery overcharging prevents the paddle regenerative control from being entered (S613), discharge control corresponding to the control level can be executed. For example, if the control level is 1 ("Yes" in S614) and the electric vehicle is a (P)HEV, the discharge control unit 121 can execute control to increase the motor share of the required torque (S615). If the control level is 2 ("Yes" in S616), the discharge control unit 121 can limit the regenerative braking of the motor (S617). According to another embodiment of the present invention, step S614 can be changed to "Is the control level 1 or higher?". In this case, when the control level is 2, the motor share of the required torque can be increased, while the regenerative braking of the motor can be limited. In addition, if the electric vehicle does not have a drive source other than the electric motor (e.g., if the electric vehicle is an EV), steps S614 and S615 can be omitted.

[0067] Subsequently, if the reasons why the paddle regeneration control cannot be accessed are resolved by the PE cooling control or the discharge control ("Yes" in S618), the access possibility notification unit 123 is notified through the predetermined output unit that a notification message indicating that the paddle regeneration control can be accessed can be output (S619).

[0068] The electric vehicle control method described above expands the possibilities for entering paddle regeneration control based on traffic information and driver intent. Therefore, paddle regeneration control has the advantage of being able to be executed without any hardware changes.

[0069] The methods described above according to embodiments of the present invention can be implemented as computer-readable code stored on a computer-readable medium. Computer-readable media include all types of recording devices that store data readable by a computer system. Examples of computer-readable media include hard disk drives (HDDs), solid-state drives (SSDs), silicon disk drives (SDDs), ROMs, RAMs, CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc.

[0070] Therefore, this disclosure should be interpreted in all respects not in a limiting manner, but rather in an illustrative manner. The scope of the invention is determined by a reasonable combination of the appended claims. All equivalent modifications made to embodiments of the invention are within the scope of the invention.

Claims

1. A method for controlling the driving of an electric vehicle that uses an electric motor as a power source, comprising: Determine the likelihood of entering a variable control function, which includes the function of variably controlling the coasting torque level using regenerative braking force; When it is determined that the variable control function cannot be accessed, determine the reason why the variable control function cannot be accessed; as well as Controls are executed in a manner corresponding to the possibility of accessing the variable control function and the reasons why the variable control function is inaccessible, to resolve the reasons why the variable control function is inaccessible. Based on the driver's intention to enter the variable control function and navigation information, the likelihood of entering the variable control function is classified into multiple levels, and The reasons why the variable control function cannot be accessed include excessively high temperatures in the powertrain's electric components or overcharging of the battery.

2. The method according to claim 1, wherein, The driver's intention to enter the variable control function is determined based on the command input for activating the variable control function, and the navigation information is determined based on whether a deceleration event has occurred within a predetermined distance ahead.

3. The method according to claim 1, wherein, In response to the reason why the variable control function cannot be accessed being the excessive temperature of the powertrain electric components and the possibility of accessing the variable control function being at level one, the control is executed by limiting the power of the battery charging and discharging.

4. The method according to claim 1, wherein, In response to the reason that the variable control function cannot be accessed being the excessive temperature of the electric components of the powertrain and the possibility of accessing the variable control function being a second level higher than the first level, the execution of the control further includes limiting the regenerative braking of the electric motor.

5. The method according to claim 1, wherein, In response to the variable control function being inaccessible due to battery overcharging and the possibility of accessing the variable control function being at level one, the control is executed to increase the share of the electric motor in the desired torque.

6. The method according to claim 1, wherein, In response to the variable control function being inaccessible due to battery overcharging and the possibility of accessing the variable control function being a second level higher than the first level, the control further includes limiting regenerative braking of the electric motor.

7. The method of claim 1, further comprising: Resolve the reason why the variable control function is inaccessible; as well as In response to resolving the reason why the variable control function is inaccessible, a notification that the variable control function is accessible is output through the output unit.

8. A non-transitory computer-readable recording medium having a program recorded thereon for performing the method according to claim 1.

9. An electric vehicle, comprising: Electric motor; as well as The control unit is configured as follows: Determine the likelihood of entering a variable control function, which includes the function of variably controlling the coasting torque level using regenerative braking force; When it is determined that the variable control function cannot be accessed, determine the reason why the variable control function cannot be accessed; as well as Controls are executed in a manner corresponding to the possibility of accessing the variable control function and the reasons why the variable control function is inaccessible, to resolve the reasons why the variable control function is inaccessible. The possibility of entering the variable control function includes multiple levels based on the driver's intention to enter the variable control function and navigation information classification, and The reasons why the variable control function cannot be accessed include excessively high temperatures in the powertrain's electric components or overcharging of the battery.

10. The electric vehicle according to claim 9, wherein, The driver's intention to enter the variable control function is determined based on the command input for activating the variable control function, and the navigation information is determined based on whether a deceleration event has occurred within a predetermined distance ahead.

11. The electric vehicle according to claim 9, wherein, In response to the variable control function being inaccessible due to excessively high temperature of the powertrain electric components and the possibility of entering the variable control function being at level one, the control unit limits the power of the battery charging and discharging.

12. The electric vehicle according to claim 9, wherein, In response to the reason that the variable control function cannot be accessed being the excessively high temperature of the electric components of the powertrain and the possibility of accessing the variable control function being the second level, which is higher than the first level, the control unit restricts the regenerative braking of the electric motor.

13. The electric vehicle according to claim 9, wherein, In response to the variable control function being inaccessible due to battery overcharging and the possibility of entering the variable control function being at level one, the control unit performs control to increase the share of the electric motor in the required torque.

14. The electric vehicle according to claim 9, wherein, In response to the variable control function being inaccessible due to battery overcharging and the possibility of entering the variable control function being a second level higher than the first level, the control unit restricts regenerative braking of the electric motor.

15. The electric vehicle according to claim 9, wherein, In response to resolving the reason why the variable control function is inaccessible, the control unit outputs a notification that the variable control function is accessible via the output unit.

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