REGENERATIVE BRAKE CONTROL METHOD OF A VEHICLE

Abstract

A regenerative braking control method of a vehicle, comprising: determining (S10) whether a specific downhill driving condition is satisfied when an accelerator pedal is released in an on-state of a regenerative braking switch, setting a target deceleration of the vehicle to a specific deceleration for downhill driving when a specific preliminary obstacle is not present in front of the vehicle when it is determined that the downhill driving condition is satisfied, determining (S30) the torque required for the vehicle to decelerate at the target deceleration, and generating (S40) the required torque in the vehicle preferably by regenerative braking.

Description

BACKGROUND OF THE PRESENT DISCLOSURE Field of the present disclosure

[0001] The present disclosure relates to a technology for controlling regenerative braking torque of a vehicle. Description of related technology

[0002] In conventional environmentally friendly commercial vehicles, a lever- or paddle-shaped regenerative braking device may be provided, and a considerable number of drivers use the regenerative braking device in a steady state without further manipulation, rather than actively manipulating the regenerative braking device appropriately to the driving condition of a vehicle.

[0003] The reason is that it is inconvenient for a driver to handle the regenerative braking device depending on the driving condition of the vehicle in order to properly adjust the amount of regenerative braking of the vehicle depending on the driving condition of the vehicle, and if the regenerative braking device is not properly controlled, the amount of regenerative braking of the vehicle will not be properly controlled, and thus the energy efficiency of the vehicle will be relatively deteriorated.

[0004] The information described in this background of the present disclosure is provided merely to enhance the understanding of the general background of the present disclosure and is not intended as an acknowledgment or any form of suggestion that this information constitutes prior art already known to a person skilled in the art. BRIEF EXPLANATION

[0005] Various aspects of the present disclosure are directed to providing a regenerative braking control method of a vehicle in which a degree of regenerative braking (hereinafter referred to as regenerative braking) appropriate for a driving situation of the vehicle can be automatically controlled, while improving driving comfort by minimizing driver intervention for regenerative braking to significantly improve energy efficiency of the vehicle.

[0006] According to one aspect of the present disclosure, the above and other objects can be achieved by providing a regenerative braking control method of a vehicle, comprising: determining whether or not a certain downhill driving condition is satisfied in response to an accelerator pedal being released in an on-state of a regenerative braking switch; setting a target deceleration of the vehicle to a certain deceleration for downhill driving in response to a certain preliminary obstacle or object or a certain candidate obstacle or object being absent in front of the vehicle (e.g., a vehicle on the road or a speed camera beside the road detected in front of the host vehicle), wherein, for example, a vehicle traveling faster than the host vehicle is disregarded for the regenerative braking control method, i.e., a "provisional" obstacle is, for example, an obstacle to be considered for the regenerative braking control method as long as it requires braking of the host vehicle (hereinafter referred to as "specific provisional obstacle") when it is determined that the downhill driving condition is met, determining a torque (herein the terms torque and moment are used synonymously) required for the vehicle to decelerate at the target deceleration, and generating the required torque in the vehicle preferably using regenerative braking.

[0007] For example, it may be determined that the downhill driving condition is satisfied when a current vehicle speed is equal to or greater than a target vehicle speed determined by adding a certain preset vehicle speed value to a vehicle speed when the accelerator pedal is released in the on state of the regenerative braking switch.

[0008] For example, when it is determined that the downhill driving condition is not satisfied, the target deceleration may be set to a minimum value among candidate decelerations determined depending on an inclination of a road on which the vehicle is traveling and the preliminary obstacle.

[0009] In response to the fact that the road on which the vehicle is traveling is a flat road or a road with an upward gradient (incline), one of the decelerations in question can be determined as a coasting deceleration or a free rolling deceleration, and the coasting deceleration can be a predetermined constant value.

[0010] In response to the fact that the road on which the vehicle is traveling is a downhill gradient, one of the candidate decelerations may be determined as the downhill deceleration, and the downhill deceleration may be adjusted depending on a difference between the target vehicle speed and the current vehicle speed.

[0011] In response to the preliminary obstacle being a speed camera (or more generally, speed enforcement device), one of the candidate decelerations may be determined as a stationary obstacle deceleration, and the stationary obstacle deceleration may be set to a deceleration required for the vehicle to reach a speed camera speed limit in response to the vehicle reaching a speed camera enforcement position.

[0012] The deceleration for stationary obstacles can be determined by the following equation: acam=(vcam2−vcur2)2×max(dcam,dmin) where: a cam : Delay for stationary obstacles v cam : Speed ​​limit of the speed or restriction camera v cur : current vehicle speed dcam : Distance from the current position of the vehicle to the speed camera d min : Minimum distance to prevent division by zero

[0013] For example, in response to the preliminary obstacle being a preceding vehicle, one of the candidate decelerations may be determined to be a moving obstacle deceleration, and the moving obstacle deceleration may be set to a deceleration required for the vehicle to maintain an appropriate inter-vehicle distance from the preceding vehicle.

[0014] The moving obstacle deceleration may, for example, be selected from a moving obstacle deceleration based on a first mode configured to be advantageous to maintain the appropriate inter-vehicle spacing to the preceding vehicle during braking of the preceding vehicle, and a moving obstacle deceleration based on a second mode configured to be advantageous to maintain the correct inter-vehicle spacing to the preceding vehicle during traveling (e.g., traveling at least substantially at a constant speed) of the preceding vehicle.

[0015] The deceleration for moving obstacles can be determined by the following equations: aref=β×actg+(1−β)×aca actg=−1h[λ(vego×h+dmin−drel)−vrel] aca=(vfront2−vego2)2×drelin mode 1 aca=(vfront−vego)22×(drel−D)in mode 2 where: a ref : Delay for moving obstacles β: Mixing ratio (setting value depends on relative speed and relative distance) h: Time gap constant for constant time gap control λ: Glide gradient (with increasing glide gradient, distance control becomes faster) v ego : Speed ​​of the host vehicle d min : minimum distance to be maintained d rel : Distance to the vehicle in front v rel : relative speed v front : Speed ​​of the vehicle ahead D: appropriate vehicle inter-vehicle distance

[0016] The appropriate inter-vehicle distance D can be determined, for example, using a map that represents an inter-vehicle distance as a function of the current vehicle speed and a relative speed of the vehicle.

[0017] If it is determined that the downhill driving condition is met, for example, in response to the presence of the preliminary obstacle in front of the vehicle, the target deceleration may be set to the minimum value among the candidate decelerations.

[0018] The required torque (e.g. braking torque) can be determined, for example, by adding a slope compensation torque (e.g. as compensation for a slope force on a downhill stretch), an air resistance compensation torque and a rolling resistance compensation torque to a reference torque obtained by multiplying the target deceleration by a vehicle weight and a dynamic load radius of the tires.

[0019] For example, the required torque can be determined by adding the tilt compensation torque and a feedback compensation torque to the reference torque obtained by multiplying the target deceleration by a vehicle weight and a dynamic load radius of the tires.

[0020] The feedback compensation torque can be determined, for example, by the following equation. Tfb=Tmot+Trtd−r×m^×aveh where: T fb : Feedback compensation torque T mot : Engine torque T rtd : Retarder moment r: dynamic load radius of the tires m̂: estimated vehicle weight a veh : current acceleration of the vehicle

[0021] When generating the required torque in the vehicle, in response to a vehicle speed being reduced to a certain conversion speed or less than the certain conversion speed, the regenerative braking torque can be gradually replaced or supplemented by a retarder torque.

[0022] According to a further aspect of the present disclosure, a regenerative braking control system of a vehicle is provided, comprising a control device configured to execute the above regenerative braking control method, wherein the regenerative braking switch is configured to provide the control device with a signal indicating the user's selection to activate a regenerative braking function of the vehicle, an accelerator pedal sensor (hereinafter referred to as accelerator pedal sensor) configured to detect a release of the accelerator pedal and to supply information relating to the accelerator pedal to the control device, and a motor or generator (motor-generator; e.g., electric motor) and a retarder (e.g., hydraulic brake) controlled by the control device and configured to generate the required torque in the vehicle.

[0023] The regenerative braking control system may further comprise, for example, a navigation system configured to provide information relating to speed cameras of a road on which the vehicle is traveling, and at least one front camera and / or a front radar (radio detection and ranging; RADAR for short) configured to acquire information relating to preceding vehicles on the road on which the vehicle is traveling.

[0024] For example, the regenerative braking control system may further include a mode selection switch configured to select the determination of the target deceleration as a different value in response to the presence of a preceding vehicle.

[0025] The methods and apparatus of the present disclosure have additional features and advantages that will be apparent from, or further explained in, the accompanying drawings included herein and the following detailed description, which together serve to explain certain principles of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a regenerative brake control system of a vehicle according to an exemplary embodiment of the present disclosure, Fig. 2 and Fig. 3 are flowcharts illustrating a regenerative braking control method of a vehicle according to an exemplary embodiment of the present disclosure, and Fig. 4 is a map showing an inter-vehicle distance as a function of a vehicle speed and a relative speed.

[0026] It should be understood that the accompanying drawings are not necessarily to scale and present a somewhat simplified representation of various features illustrating the basic principles of the present disclosure. The predetermined design features of the present disclosure as set forth herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the particular intended application and environment of use.

[0027] In the figures, reference numerals refer to the same or equivalent parts of the present disclosure. DETAILED DESCRIPTION

[0028] Reference will now be made in detail to various embodiments of the present disclosure, examples of which are shown in the accompanying drawings and described below. Although the present disclosure will be described in connection with exemplary embodiments of the present disclosure, the present description is not intended to limit the present disclosure to these exemplary embodiments of the present disclosure. On the contrary, the present disclosure is intended to cover not only the exemplary embodiments of the present disclosure, but also various alterations, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the present disclosure as defined by the appended claims.

[0029] Reference will now be made in detail to exemplary embodiments of the present disclosure, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts, and redundant description thereof will be omitted.

[0030] In the following description of the embodiments, suffixes such as "...module", "...part", "...device", "...unit" are used interchangeably only to simplify the explanation of the description and do not have different meanings or functions.

[0031] In the following description of the exemplary embodiments of the present disclosure, a detailed description of known functions and configured embodiments is omitted when doing so might make the subject matter of the present disclosure rather unclear. Furthermore, the accompanying drawings are provided by way of example to describe the exemplary embodiments of the present disclosure and should not be construed as being limited to the exemplary embodiments set forth herein, and it is understood that the exemplary embodiments of the present disclosure are provided only to fully comprise the present disclosure and to cover modifications, equivalents, or variations that fall within the spirit and scope of the present disclosure.

[0032] In the following description of the embodiments, terms such as "first..." and "second..." are used only to describe various elements, and these elements should not be construed as being limited by these terms. These terms are used only to distinguish one element from other elements.

[0033] When an element or layer is described as "connected to" or "coupled to" another element or layer, it may be directly connected or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, an element or layer described as "directly connected to" or "directly coupled to" another element or layer may have no intervening elements or layers.

[0034] The singular expressions used herein may also include plural expressions unless the context clearly indicates otherwise.

[0035] In the following description of the embodiments, terms such as "comprises", "having", "comprising", "including", "having", "with", etc. are inclusive and therefore specify the presence of the stated features, integers, steps, operations, elements, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0036] With reference to Fig. 1, a regenerative braking control system of a vehicle according to an exemplary embodiment of the present disclosure includes a control device 1 configured to execute a regenerative braking control method described below, a regenerative braking switch 3 configured to provide the control device 1 with a signal indicating the user's selection to activate a regenerative braking function of the vehicle, an accelerator pedal sensor 5 configured to detect a release of an accelerator pedal and provide the control device 1 with information regarding the accelerator pedal, and a motor 7 and a retarder 9 controlled by the control device 1 and configured to generate the torque required by the vehicle.

[0037] That is, the regenerative braking switch 3 is provided to be turned on by a user, such as a driver, to activate the regenerative braking control function of the vehicle, or to be turned off by the user, and the control device 1 automatically executes the regenerative braking control method according to an exemplary embodiment of the present disclosure described below, depending on the driving situation of the vehicle only by turning on the regenerative braking switch 3.

[0038] Furthermore, the regenerative braking control system according to an exemplary embodiment of the present disclosure may include a navigation system 11 configured to provide information related to ahead speed cameras of a road on which the vehicle is traveling, and at least one of a front camera 13 and a front radar (RADAR) 15 configured to acquire information related to ahead vehicles on the road on which the vehicle is traveling.

[0039] In addition, information related to physical quantities related to the running of the vehicle, such as a vehicle speed and a vehicle acceleration, is inputted to the control device 1 from various sensors of the vehicle, which are not shown.

[0040] Furthermore, the regenerative braking control according to an exemplary embodiment of the present disclosure may include a mode selection switch 17 configured to select the determination of a target deceleration, which will be described later, as a different value when a preceding vehicle is present.

[0041] With reference to Fig. 2 and Fig. 3, the regenerative braking control method of the vehicle according to various exemplary embodiments of the present disclosure includes: determining whether or not a certain downhill driving condition is satisfied when the accelerator pedal is released in the on-state of the regenerative braking switch 3 (S10), setting a target deceleration of the vehicle to a certain deceleration for downhill driving when a certain preceding obstacle is not present in front of the vehicle when it is determined that the downhill driving condition is satisfied (S20), determining the required torque of the vehicle, that is, torque required for the vehicle to decelerate at the target deceleration (S30), and generating the required torque in the vehicle preferably using regenerative braking.

[0042] That is, the control device 1 is configured to determine whether or not the downhill driving condition is satisfied when it is confirmed that a driver does not intend to further accelerate the vehicle via an accelerator pedal sensor 5 after releasing the accelerator pedal in the on state of the regenerative braking switch 3.

[0043] The downhill driving condition may be set to be satisfied when a current vehicle speed is equal to or greater than a target vehicle speed determined by adding a certain preset vehicle speed value to a vehicle speed when the accelerator pedal is released in the on state of the regenerative braking switch 3.

[0044] Here, the preset vehicle speed value is a tuning value that can be set to, for example, 1 km / h, 2 km / h, or the like, and the total obtained by adding the preset vehicle speed value to the vehicle speed when the accelerator pedal is released becomes the target vehicle speed, and it is determined that the downhill driving condition is satisfied when the current vehicle speed is equal to or greater than the target vehicle speed.

[0045] That is, the downhill descent condition is satisfied when the vehicle speed is equal to or greater than the target vehicle speed obtained by adding a small margin of the preset vehicle speed to the vehicle speed at a time when the driver releases the accelerator pedal, and the vehicle automatically enters a downhill descent state by setting the target deceleration of the vehicle to the deceleration for downhill descent when the preliminary obstacle does not exist in front of the vehicle and controlling the vehicle with the torque required for the vehicle to decelerate at the target deceleration.

[0046] Therefore, according to an exemplary embodiment of the present disclosure, assuming that the regenerative braking switch 3 is turned on, only when the driver releases the accelerator pedal, the vehicle is automatically decelerated at the deceleration for downhill driving when it is determined that the downhill driving condition is satisfied, and thus the vehicle is in the downhill driving state.

[0047] Of course, the control device 1 decelerates the vehicle with a different target deceleration when the downhill driving condition is not satisfied or in other driving situations such as when the preliminary obstacle is present, and in this case, the regenerative braking function of the vehicle is also preferentially used.

[0048] Therefore, unlike the conventional method, the regenerative braking control method according to an exemplary embodiment of the present disclosure does not require the operation of a separate switch to control the vehicle on a downhill slope, and is capable of increasing the amount of regenerative braking of the vehicle while significantly improving driver comfort, thus significantly contributing to improving the energy efficiency of the vehicle.

[0049] If the downhill driving condition is not met, the target deceleration is set to the minimum value among the candidate decelerations determined depending on the gradient of the road on which the vehicle is traveling and the preliminary obstacle.

[0050] In this case, the decelerations in question can be determined before determining the downhill condition, as in the Fig. 2 illustrated embodiment.

[0051] For reference, a delay for coasting in advance is set to a constant value as described below, and although Fig. 2 shows that a coasting deceleration setting operation is performed, when the accelerator pedal is released, the coasting deceleration setting operation is actually omitted.

[0052] Although Fig. 2 shows that an operation for determining the deceleration for downhill travel, an operation for determining a deceleration for stationary obstacles, and an operation for determining a deceleration for moving obstacles are executed sequentially, these operations may be executed simultaneously or in a different order.

[0053] When the road on which the vehicle is traveling is a flat road or an uphill slope, the coasting deceleration is determined as one of the decelerations to be considered, and the coasting deceleration is a predetermined constant value.

[0054] For example, the deceleration for coasting can be set to a certain constant value, such as 0.3 m / s 2 or 0.4 m / s 2 , can be set.

[0055] When the road on which the vehicle is traveling is a flat road or an uphill road, the target deceleration is set to the deceleration for coasting including the constant described above, the required torque to meet the target deceleration is determined, and the vehicle is controlled with the required torque.

[0056] A commercial vehicle, such as a truck, may have a large weight change and therefore essentially requires compensation of the vehicle weight and the road gradient during the regenerative braking control of the vehicle, and in an exemplary embodiment of the present disclosure, the compensation of the vehicle weight and the road gradient may be performed during the process of determining the required torque to implement the deceleration of the vehicle set to the constant value.

[0057] Consequently, the amount of regenerative deceleration of the vehicle is increased when the vehicle weight is increased, and the amount of regenerative deceleration of the vehicle is decreased when the vehicle is traveling on an uphill slope.

[0058] If the road on which the vehicle is traveling is a downhill gradient, one of the candidate decelerations is determined as the downhill deceleration, and the downhill deceleration is set depending on a difference between the target vehicle speed and the current vehicle speed.

[0059] For example, the deceleration for downhill driving can be set to be proportional to the difference between the target vehicle speed and the current vehicle speed.

[0060] In the present case, when the current vehicle speed becomes greater than the target vehicle speed, the deceleration for downhill driving is increased, and thereby, when the vehicle speed increases on a downhill road, the vehicle is decelerated with a deceleration increased by as much as the difference between the target vehicle speed and the current vehicle speed increases, and thereby the current vehicle speed can be quickly converged to the target vehicle speed.

[0061] Here, the temporary obstacle in front of the vehicle is a speed camera, a vehicle ahead or something similar.

[0062] If the preliminary obstacle is a speed camera, one of the possible delays is the stationary obstacle delay.

[0063] The stationary obstacle delay is set to a delay required for the vehicle to reach the speed camera speed limit when the vehicle reaches a speed camera enforcement position.

[0064] That is, the deceleration for stationary obstacles can be determined by the following equation. acam=(vcam2−vcur2)2×max(dcam,dmin) where: a cam : Delay for stationary obstacles v cam : Speed ​​limit of the restriction or speed camera v cur : current vehicle speed d cam : Distance from the current position of the vehicle to the speed camera d min : Minimum distance to prevent division by zero

[0065] That is, when a speed camera is present ahead on the road on which the vehicle is traveling, the control device 1, having received information related to the speed camera from devices such as the navigation system 11, is configured to determine the deceleration for stationary obstacles by the equation described above, is configured to determine the required torque, and satisfies the required torque preferably using regenerative braking of the vehicle, being capable of maximizing regenerative braking as much as possible while decelerating the vehicle so as not to exceed the speed limit when the vehicle reaches the enforcement position of the speed camera.

[0066] If the preliminary obstacle is a vehicle ahead, one of the possible decelerations is determined as a moving obstacle deceleration.

[0067] The deceleration for moving obstacles is set to a deceleration required for the vehicle to maintain an appropriate distance from the vehicle in front or an appropriate inter-vehicle distance.

[0068] In the exemplary embodiment of the present disclosure, the moving obstacle deceleration may be one selected from a moving obstacle deceleration based on a first mode advantageous for maintaining the appropriate inter-vehicle distance with the preceding vehicle during braking of the preceding vehicle and a moving obstacle deceleration based on a second mode advantageous for maintaining the appropriate inter-vehicle distance with the preceding vehicle during traveling of the preceding vehicle.

[0069] That is, the deceleration for moving obstacles can be determined by the following equations. aref=β×actg+(1−β)×aca actg=−1h[λ(vego×h+dmin−drel)−vrel] aca=(vfront2−vego2)2×drelin mode 1 aca=(vfront−vego)22×(drel−D)in mode 2 where: a ref : Delay for moving obstacles β: Mixing ratio (tuning value depending on the relative speed and the relative distance), where the relative speed refers to the speed difference between the host vehicle and the vehicle in front and the relative distance refers to the distance between the host vehicle and the vehicle in front. h: Time gap constant for constant time gap control λ: Glide gradient (with increasing glide gradient, distance control becomes faster) v ego : Speed ​​of the host vehicle d min : minimum distance to be maintained d rel : Distance to the vehicle in front v rel : relative speed v front : Speed ​​of the vehicle ahead D: appropriate vehicle inter-vehicle distance

[0070] Here, the appropriate inter-vehicle distance D can be determined using a map that represents the inter-vehicle distance as a function of the current vehicle speed and the relative speed.

[0071] Of course, the map is designed in advance through a series of experiments and analyses, and a single map can be provided as in Fig. 4, or a plurality of maps or three-dimensional maps may be provided so that a user can select a desired map to set the appropriate inter-vehicle distance to a longer or a shorter distance even with the same (e.g., unchanged) current vehicle speed and relative speed.

[0072] When a preceding vehicle is present on the road on which the vehicle is traveling, the control device 1, which has received information regarding the preceding vehicle from devices such as the front camera 13 or the front radar (Radio Detection and Ranging) 15, is configured to determine the deceleration for moving obstacles using the equations described above, is configured to determine the required torque, and preferably satisfies the required torque by regenerative braking of the vehicle, being capable of maximizing the regenerative braking as much as possible while decelerating the vehicle to maintain the appropriate inter-vehicle distance and the preceding vehicle.

[0073] Here the delay for moving obstacles is ref to a value based on Mode 1 when the deceleration for moving obstacles is a refusing a ca determined in Mode 1 and becomes a value based on Mode 2 when the deceleration for moving obstacles is ref using a ca is determined in mode 2.

[0074] The Mode 1-based moving obstacle deceleration is a deceleration determined under the assumption that the position of the preceding vehicle is fixed, and is beneficial for maintaining the inter-vehicle distance during braking of the preceding vehicle because the inter-vehicle distance tends to increase at the same rate as the moving distance of the preceding vehicle.

[0075] On the other hand, the Mode 2-based moving obstacle deceleration is a deceleration determined under the assumption that the preceding vehicle is traveling, and is advantageous for maintaining a desired inter-vehicle distance during the traveling of the preceding vehicle.

[0076] In an exemplary embodiment of the present disclosure, the mode selection switch 17 is provided to allow a user to select between the first mode and the second mode, so that the deceleration for moving obstacles is determined and applied based on the first mode or determined and applied based on the second mode, thereby making it possible to meet various user requirements.

[0077] When the downhill condition is met but the preliminary obstacle is present ahead, the target deceleration is set to the minimum value among the candidate decelerations mentioned above.

[0078] That is, the control device 1 sets the target deceleration to the minimum value among the candidate decelerations described above in a situation where the downhill driving condition is satisfied but a speed camera or a preceding vehicle is present and therefore it is difficult for the vehicle to easily travel on a downhill road, thereby enabling the vehicle to maximize regenerative braking as much as possible while decelerating the vehicle while maintaining a speed limit controlled by the speed camera or maintaining a desired inter-vehicle distance from the preceding vehicle.

[0079] The required torque can be determined by adding the tilt compensation torque, the air resistance compensation torque and the rolling resistance compensation torque to the reference torque, which is determined by multiplying the target deceleration by the vehicle weight and a dynamic load radius of the tires.

[0080] Such determination of the required torque can be referred to as vehicle dynamics-based control (open loop control), and in the present case, the pitch compensation torque, the drag compensation torque and the rolling resistance compensation torque are usually determined based on vehicle dynamics, so a detailed description of the methods for determining them is omitted.

[0081] Otherwise, the required torque can be determined by adding the tilt compensation torque and the feedback compensation torque to the reference torque obtained by multiplying the target deceleration by the vehicle weight and the dynamic load radius of the tires.

[0082] Such a determination of the required torque can be referred to as closed loop control, which is set up to follow the target deceleration.

[0083] The feedback compensation torque can be determined using the following equation. Tfb=Tmot+Trtd−r×m^×aveh where: T fb : Feedback compensation torque T mot : Engine torque T rtd : Retarder moment r: dynamic load radius of the tires m̂: estimated vehicle weight a veh: current acceleration of the vehicle

[0084] That is, the engine torque and the retarder torque may be torques commanded to the engine 7 and the retarder 9 by the control device 1, r × m̂ × a veh a torque determined based on the current acceleration of the vehicle, and the feedback compensation torque may be a difference between a target value and a result or actual value.

[0085] When generating the required torque in the vehicle, the regenerative braking torque can be controlled to be gradually replaced by the retarder torque when the vehicle speed is reduced to a certain conversion speed or less than the certain conversion speed.

[0086] Regenerative braking by the motor 7 may be prohibited at a certain lower vehicle speed limit for reasons such as ensuring the durability of a transmission due to the characteristics of the transmission used in vehicles. When the vehicle speed is reduced to the conversion speed set to a slightly higher speed than the lower vehicle speed limit or less, the regenerative braking torque generated by the motor 7 may be gradually replaced by a retarder torque so as not to perform regenerative braking by the motor 7 at the lower vehicle speed limit or less, thereby making it possible to prevent deterioration of the durability of the vehicle.

[0087] That is, for example, assuming that the lower vehicle speed limit is 20 km / h, the conversion speed may be set to 23 km / h, which is slightly higher than the lower vehicle speed limit, and the regenerative braking torque is gradually replaced by the retarder torque when the vehicle speed is reduced to (or less than) 23 km / h while performing regenerative braking according to an exemplary embodiment of the present disclosure, and the regenerative braking torque becomes 0 when the vehicle speed reaches 20 km / h in order to prevent deterioration of the durability of the transmission of the vehicle, or the like.

[0088] As apparent from the above description, in a regenerative braking control method of a vehicle according to an exemplary embodiment of the present disclosure, a degree of regenerative braking suitable for a driving situation of the vehicle can be automatically controlled while improving driving comfort by minimizing driver intervention for regenerative braking to significantly improve energy efficiency of the vehicle.

[0089] Furthermore, a term referring to a control device, such as "controller," "control unit," "control device," "control module," "server," etc., refers to a hardware device having a memory and a processor configured to perform one or more steps interpreted as an algorithm structure. The memory stores algorithm steps, and the processor executes the algorithm steps to perform one or more operations of a method according to various example embodiments of the present disclosure.The control device according to exemplary embodiments of the present disclosure may be implemented by a non-volatile memory configured to store algorithms for controlling the operation of various components of a vehicle or data via software instructions for executing the algorithms, and a processor configured to perform the above-described process using the data stored in the memory. The memory and the processor may be individual chips. Alternatively, the memory and the processor may be integrated into a single chip. The processor may be implemented as one or more processors.The processor may include various logic circuits and operating circuits, may be configured to process operations according to a program provided from the memory, and may be configured to generate a control signal according to the processing result.

[0090] The control device may be at least one microprocessor operated by a predetermined program that may include a series of instructions for performing the method included in the above-mentioned numerous exemplary embodiments of the present disclosure.

[0091] The above invention may also be embodied in the form of computer-readable code on a computer-readable recording medium. The computer-readable recording medium is any data storage device capable of storing data that can subsequently be read by a computer system and of storing and executing program instructions that can subsequently be read by a computer system. Examples of computer-readable recording media include hard disk drives (HDDs), solid-state disks (SSDs), silicon floppy disk drives (SDDs), read-only memories (ROMs), random access memories (RAMs), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc., and are embodied in the form of carrier waves (e.g., when transmitted over the Internet).Examples of program instructions include both machine language code, such as that generated by a compiler, and high-level language code that can be executed by a computer using an interpreter or similar.

[0092] In various exemplary embodiments of the present disclosure, each operation described above may be performed by one control device, and the control device may be implemented by a plurality of control devices or an integrated single control device.

[0093] In various exemplary embodiments of the present disclosure, the memory and the processor may be provided as one chip or as separate chips.

[0094] In various exemplary embodiments of the present disclosure, the scope of the present disclosure includes software or machine-executable instructions (e.g., an operating system, an application, firmware, a program, etc.) to enable performance of operations according to the methods of various embodiments on a device or computer, and a non-transitory computer-readable medium containing such software or instructions stored thereon and executable on the device or computer.

[0095] In various exemplary embodiments of the present disclosure, the control device may be implemented in hardware or software, or in a combination of hardware and software.

[0096] Furthermore, terms such as "...unit", "...module", "...device", etc., contained in the description are units for performing at least one function or operation, which may be implemented by hardware, software, or a combination thereof.

[0097] For ease of explanation and to accurately define the appended claims, the terms "upper...", "lower...", "inner...", "outer...", "top," "bottom," "upward," "downward," "front...", "backward...", "front," "backward," "inside," "outside," "inward," "outside," "forward," and "backward" are used to describe features of the exemplary embodiments with reference to positions of those features shown in the drawings. It is further understood that the term "connect" or its variations refer to both direct and indirect connection.

[0098] The term "and / or" can include a combination of a plurality of related listed items or any one of a plurality of related listed items. For example, "A and / or B" includes all three cases, such as "A," "B," and "A and B."

[0099] In this specification, unless otherwise stated, a singular term includes a plural term unless the context clearly indicates otherwise.

[0100] In exemplary embodiments of the present disclosure, "at least one of A and B" may refer to "at least one of A or B" or "at least one of combinations of at least one of A and B." Furthermore, "one or more of A and B" may refer to "one or more of A or B" or "one or more combinations of one or more of A and B."

[0101] In the exemplary embodiment of the present disclosure, it is to be understood that a term such as "comprising", "having", "including", etc., is intended to indicate that the features, numbers, steps, acts, elements, parts, or combinations thereof described in the specification are present, and does not exclude the possibility that one or more other features, numbers, steps, acts, elements, parts, or combinations thereof are added or present.

[0102] The foregoing descriptions of specific exemplary embodiments of the present disclosure have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed, and, of course, many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application in order to enable those skilled in the art to make and use various exemplary embodiments of the present disclosure, as well as various alterations and modifications thereof. The scope of the present disclosure is intended to be defined by the appended claims and their equivalents.

Claims

[1] A regenerative braking control method of a vehicle, the method comprising: Determining (S10), by a control device (1), whether or not a certain downhill driving condition is met in response to an accelerator pedal being released in an on-state of a regenerative braking switch (3), Setting a target deceleration of the vehicle to a specific deceleration for downhill driving in response to a specific preliminary obstacle not being present in front of the vehicle when it is determined that the downhill driving condition is met, Determining (S30) the torque required for the vehicle to decelerate at the target deceleration, and Generating (S40) the required torque in the vehicle using regenerative braking. [2] The regenerative braking control method according to claim 1, wherein the control device (1) determines that the downhill driving condition is satisfied in response to a current vehicle speed being equal to or greater than a target vehicle speed determined by adding a certain preset vehicle speed value to a vehicle speed in response to the accelerator pedal being released in the on-state of the regenerative braking switch (3). [3] The regenerative braking control method according to claim 2, wherein, when determining (S10) that the downhill driving condition is not satisfied, the target deceleration is set to a minimum value among candidate decelerations determined depending on the slope of a road on which the vehicle is traveling and the preliminary obstacle. [4] Regenerative braking control method according to claim 3, wherein in response to the fact that the road on which the vehicle is traveling is a level road or an uphill gradient, one of the candidate decelerations is determined to be a coast-to-stop deceleration, and the deceleration for coasting is a predetermined constant value. [5] Regenerative braking control method according to claim 3 or 4, wherein in response to the fact that the road on which the vehicle is traveling is a downhill gradient, one of the candidate decelerations is determined to be the downhill deceleration, and the deceleration for downhill driving is set depending on a difference between the vehicle target speed and the current vehicle speed. [6] Regenerative braking control method according to claim 3, 4 or 5, wherein in response to the preliminary obstacle being a speed camera, one of the candidate decelerations is determined to be a stationary obstacle deceleration, and the stationary obstacle deceleration is set to a deceleration required for the vehicle to reach a speed camera speed limit in response to the vehicle reaching a speed camera enforcement position. [7] The regenerative braking control method according to claim 6, wherein the deceleration for stationary obstacles is determined by the following equation: acam=(vcam2−vcur2)2×max(dcam,dmin), where a cam : Delay for stationary obstacles, v cam : Speed ​​limit of the speed camera, v cur : current vehicle speed, d cam: Distance from the current position of the vehicle to the speed camera, and d min : Minimum distance to prevent division by zero. [8] Regenerative braking control method according to any one of the preceding claims 3 to 7, wherein in response to the preliminary obstacle being a preceding vehicle, one of the candidate decelerations is determined to be a moving obstacle deceleration, and the deceleration for the moving obstacles is set to a deceleration required for the vehicle to maintain an appropriate inter-vehicle distance from the vehicle in front. [9] The regenerative braking control method according to claim 8, wherein the moving obstacle deceleration is one selected from a moving obstacle deceleration according to a first mode arranged to be advantageous for maintaining the appropriate inter-vehicle distance from the preceding vehicle during braking of the preceding vehicle, and a moving obstacle deceleration according to a second mode arranged to be advantageous for maintaining the appropriate inter-vehicle distance from the preceding vehicle during traveling of the preceding vehicle. [10] The regenerative braking control method according to claim 9, wherein the deceleration for moving obstacles is determined by the following equations: aref=β×actg+(1−β)×aca actg=−1h[λ(vego×h+dmin−drel)−vrel] aca=(vfront2−vego2)2×drelin mode 1 aca=(vfront−vego)22×(drel−D)in mode 2, where a ref : Deceleration for moving obstacles, β: Mixing ratio (setting value depends on relative speed and relative distance), h: time gap constant for constant time gap control, λ: Glide gradient (with increasing glide gradient, distance control becomes faster), v ego : Speed ​​of the host vehicle, d min : minimum distance to be maintained, d rel : Distance to the vehicle in front, v rel : relative speed, v front : speed of the vehicle ahead, and D: reasonable inter-vehicle distance. [11] The regenerative braking control method according to claim 10, wherein the appropriate inter-vehicle distance D is determined from a map representing an inter-vehicle distance depending on the current vehicle speed and a relative speed of the vehicle. [12] The regenerative braking control method according to any one of claims 3 to 11, wherein, when it is determined that the downhill driving condition is satisfied in response to the provisional obstacle being present in front of the vehicle, the target deceleration is set to the minimum value among the candidate decelerations. [13] A regenerative braking control method according to any one of the preceding claims, wherein the required torque is determined by adding a tilt compensation torque, an air resistance compensation torque and a rolling resistance compensation torque to a reference torque obtained by multiplying the target deceleration by a vehicle weight and a dynamic load radius of the tires. [14] A regenerative braking control method according to any one of the preceding claims, wherein the required torque is determined by adding a tilt compensation torque and a feedback compensation torque to a reference torque obtained by multiplying the target deceleration by a vehicle weight and a dynamic load radius of the tires. [15] The regenerative braking control method according to claim 14, wherein the feedback compensation torque is determined by the following equation: Tfb=Tmot+Trtd−r×m^×aveh, where T fb : feedback compensation torque, T mot : engine torque, T rtd : retarder moment, r: dynamic load radius of the tires, m̂: estimated vehicle weight, and a veh : current acceleration of the vehicle. [16] A regenerative braking control method according to any one of the preceding claims, wherein, in generating the required torque in the vehicle in response to a vehicle speed being reduced to a certain conversion speed or below the certain conversion speed, the regenerative braking torque is replaced by a retarder torque. [17] A regenerative brake control system of a vehicle, the system comprising: a control device (1) arranged to carry out the regenerative braking control method according to any one of the preceding claims, wherein a regenerative braking switch (3) is arranged to provide the control device (1) with a signal indicating the user's selection to activate a regenerative braking function of the vehicle, an accelerator pedal sensor (5) configured to detect the release of the accelerator pedal and to provide the control device (1) with information relating to the accelerator pedal, and a motor (7) and a retarder (9) controlled by the control device (1) and arranged to generate the required torque in the vehicle. [18] A regenerative brake control system of a vehicle according to claim 17, further comprising: a navigation system (11) arranged to supply information relating to speed cameras ahead of a road on which the vehicle is traveling, and at least one of a front camera (13) or a front radar (15) arranged to acquire information relating to preceding vehicles on the road on which the vehicle is traveling. [19] A regenerative brake control system of a vehicle according to claim 17 or 18, further comprising a mode selection switch (17) arranged to select the determination of the target deceleration as another value in response to the presence of a preceding vehicle.

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