Starting control system and method of electric vehicle

Abstract

A start control system and method for an electric vehicle capable of satisfying a driver's demand for a high performance vehicle by implementing high performance of the electric vehicle. The system and method maximizes acceleration at an initial stage of starting the electric vehicle from a stationary state, thereby shortening the time to reach maximum acceleration when starting the electric vehicle from the stationary state.

Description

Technical Field

[0001] The present disclosure relates to a starting control system and method for an electric vehicle. More specifically, the present disclosure relates to a starting control system and method for an electric vehicle, which can meet the needs of high-performance vehicles by controlling the maximum starting performance when the vehicle is stopped. Background Art

[0002] In recent years, research, development, and release of environmentally friendly vehicles such as hybrid electric vehicles, fuel cell electric vehicles, and electric vehicles have been ongoing.

[0003] Figure 1 is a schematic diagram showing a control configuration for driving a motor of a conventional electric vehicle.

[0004] like Figure 1 As shown, a front wheel motor 31 that outputs driving torque to the front wheels and a rear wheel motor 32 that outputs driving torque to the rear wheels may be installed in the electric vehicle.

[0005] Furthermore, the torque of the front wheel motor 31 is controlled by a first motor controller 21 (MCU) which is a type of motor control inverter. The torque of the rear wheel motor 32 is controlled by a second motor controller 22 which is a type of motor control inverter.

[0006] To this end, the vehicle controller 10 is connected to the first motor controller 21 and the second motor controller 22 to implement the torque command. In addition, the vehicle controller 10 is connected to the battery management system 40 to implement electrical signal transmission.

[0007] When the information for determining the torque command value, the front wheel actual output torque and the front wheel motor available torque transmitted from the first motor controller 21 are input to the vehicle controller 10, the rear wheel actual output torque and the rear wheel motor available torque transmitted from the second motor controller 22 are input to the vehicle controller 10. In addition, the available battery power and the current battery power (SoC, state of charge) transmitted from the battery management system 40 are input to the vehicle controller 10.

[0008] Furthermore, information for determining a torque command value, an accelerator pedal input signal, a brake pedal input signal, a shift position input signal, and the like are input to the vehicle controller 10 .

[0009] Accordingly, when the accelerator pedal input signal, the brake pedal input signal, and the shift gear input signal are input to the vehicle controller 10, the vehicle controller 10 determines the front wheel motor torque command value and the rear wheel motor torque command value. The determination is based on the front wheel actual output torque and the front wheel available torque transmitted from the first motor controller 21, the rear wheel actual output torque and the rear wheel available torque transmitted from the second motor controller 22, and the available battery power and the current battery power transmitted from the battery management system 40.

[0010] Subsequently, the vehicle controller 10 sends the front wheel motor torque command value and the rear wheel motor torque command value to the first motor controller 21 and the second motor controller 22, respectively. As a result, the front wheel motor 31 can be operated by torque control according to the front wheel motor torque command value of the first motor controller 21, and the rear wheel motor 32 can be operated by torque control according to the rear wheel motor torque command value of the second motor controller 22.

[0011] When the electric vehicle is driven by the above motor control, the motor torque can be output as the maximum torque from the start when the vehicle is stationary, and the instantaneous acceleration can be achieved by the maximum torque output of the motor. The separate starting device or starting control system used in general internal combustion engine vehicles is not adopted.

[0012] In other words, in the use case of an electric vehicle, since the acceleration generated by the output of the maximum torque of the motor in the initial start from a standstill is faster than the acceleration of a general internal combustion engine vehicle, there is not much demand for a driving mode for achieving rapid acceleration through the starting control used in a general internal combustion engine vehicle.

[0013] However, for high-performance electric vehicles, given the emphasis on 0 to 100 kph acceleration performance in drag racing, the technology and ability to maximize acceleration during launch is considered an indicator of high performance. Ongoing research and development efforts are aimed at reducing the time required for electric vehicles to reach maximum acceleration.

[0014] The above information disclosed in this Background section is only for enhancing understanding of the background of the present disclosure. Therefore, the Background section may contain information that does not constitute the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0015] The present disclosure is dedicated to solving the above-mentioned problems associated with the prior art. The purpose of the present disclosure is to provide a starting control system and method for an electric vehicle, which can meet the driver's demand for a high-performance vehicle. This is achieved by shortening the time to reach the maximum acceleration in the initial stage of starting the electric vehicle from a stationary state. As a result, a high-performance electric vehicle and a maximum acceleration of the electric vehicle are achieved.

[0016] In one aspect, the present disclosure provides a start control system for an electric vehicle, including an audio, video and navigation (AVN) system configured to select a road grip level and start control activation, and an accelerator pedal detector configured to detect the amount of depression of an accelerator pedal. The start control system also includes a brake pedal detector and a vehicle controller, the brake pedal detector being configured to detect the amount of depression of the brake pedal, and the vehicle controller being configured to execute a first stage start control when a first stage start control entry condition is satisfied based on a start control activation signal from the AVN system, a detection signal of the accelerator pedal detector, and a detection signal of the brake pedal detector. The vehicle controller is also configured to execute a second stage start control in which a pre-motor torque is applied to a motor when a second stage start control condition is satisfied in a state in which the first stage start control is executed, and to execute a third stage assist control mode when the brake pedal is released in a state in which the second stage start control is executed.

[0017] In one embodiment, the vehicle controller may be configured to: execute the first stage start control when all first stage start control entry conditions are satisfied. The first stage start control entry conditions include the conditions that the current driving mode of the vehicle may not be in the power-assist mode or the cruise mode, the temperature of the motor controller may be equal to or less than a specific temperature, the temperature of the insulated gate bipolar transistor (IGBT) of the motor may be less than or equal to a specific temperature, and the cooling time may be longer than a reference time.

[0018] In another embodiment, the vehicle controller may be configured to execute the second stage launch control when all second stage launch control entry conditions are satisfied. The second stage launch control entry conditions include the conditions that the drive mode may be selected as the sport mode or the sport+ mode, the electronic stability control (ESC) may be turned off, the gear shift may be set to drive (D), the steering angle of the steering wheel may be less than a specific angle, and the accelerator pedal travel may exceed a specific level, and the brake pedal travel may exceed a specific level.

[0019] In another embodiment, the vehicle controller can be configured to: when the accelerator pedal and the brake pedal are pressed simultaneously, determine the larger torque value of the motor torque determined from the motor torque application map according to the road grip level and the motor torque determined from the motor torque application map as the pre-motor torque to be pre-applied to the motor.

[0020] In yet another embodiment, when the pre-motor torque determined by the vehicle controller is transmitted to the motor controller, the pre-motor torque may be applied to the motor through torque control of the motor controller.

[0021] In yet another embodiment, the start control system may further include: an instrument panel configured to display guidance information for start control execution based on the start control state information received from the vehicle controller.

[0022] In a further embodiment, the vehicle controller may be configured to determine a virtual engine speed when performing the second stage starting control, and transmit the determined virtual engine speed to the sound controller.

[0023] In another further embodiment, the sound controller may be configured to determine a virtual engine volume according to the virtual engine speed, and output the determined virtual engine volume through a speaker.

[0024] In yet a further embodiment, the vehicle controller may be configured to perform control for executing the first stage starting control again when any one of the second stage starting control entry conditions is not satisfied while executing the second stage starting control for applying the pre-motor torque.

[0025] In yet a further embodiment, the vehicle controller may be configured to compulsorily release the starting control when a time for executing the second stage starting control for applying the pre-motor torque exceeds a reference time.

[0026] In yet a further embodiment, the vehicle controller may be configured to execute a third stage assist control mode when it is confirmed that the brake pedal is released within a reference time while the second stage starting control for applying the pre-motor torque is executed.

[0027] In yet a further embodiment, the vehicle controller may be configured to measure a cooling time when the third stage power assist control mode ends.

[0028] On the other hand, the present disclosure provides a starting control method for an electric vehicle. The starting control method includes: determining by a vehicle controller whether a road grip level is selected; determining by the vehicle controller whether a starting control activation is selected and whether a first-stage starting control entry condition is satisfied; and when the road grip level and the starting control activation are selected and the first-stage starting control entry condition is satisfied, the vehicle controller performs the first-stage starting control. The starting control method also includes: when the second-stage starting control entry condition is satisfied in a state where the first-stage starting control is executed, the vehicle controller performs the second-stage starting control for applying a pre-motor torque to the motor; and when it is confirmed that the brake pedal is released when the second-stage starting control is executed, the vehicle controller performs the third-stage power assist control mode.

[0029] In one embodiment, executing the second stage starting control may include: determining, by the vehicle controller, a larger torque value of a motor torque determined from a motor torque application map according to the road grip level and a motor torque determined from a motor torque application map when the accelerator pedal and the brake pedal are simultaneously depressed as the pre-motor torque. Executing the second stage starting control may also include: transmitting the determined pre-motor torque to a motor controller by the vehicle controller; and applying the pre-motor torque to the motor through torque control of the motor controller.

[0030] In another embodiment, the start control method may further include: displaying, through an instrument panel, guidance information for performing start control based on the start control state information received from the vehicle controller.

[0031] In yet another embodiment, the start control method may further include: when executing the second stage start control, determining a virtual engine speed by the vehicle controller; and sending the virtual engine speed to the sound controller by the vehicle controller. The start control method may further include: determining a virtual engine volume by the sound controller according to the virtual engine speed; and outputting the determined virtual engine volume through a speaker.

[0032] In yet another embodiment, when the second stage starting control for applying the pre-motor torque is executed, when it is confirmed that the brake pedal is released within a reference time, the third stage assist control mode may be executed.

[0033] In yet another embodiment, the starting control method may further include: when any one of the second stage starting control entry conditions is not satisfied in the state of executing the second stage starting control for applying the pre-motor torque, the vehicle controller performs control for executing the first stage starting control again. The starting control method may further include: when the time for executing the second stage starting control for applying the pre-motor torque exceeds a reference time, the vehicle controller forcibly releases the second stage starting control; and the vehicle controller measures a cooling time when the third stage power assist control mode ends.

[0034] Other aspects and embodiments of the disclosure are discussed below.

[0035] It should be understood that the term "vehicle" or other similar terms used herein generally include motor vehicles. Such motor vehicles may include sports utility vehicles (SUVs), buses, trucks, various commercial vehicles, etc. Such motor vehicles may also include watercraft with various ships, aircraft, etc. Such motor vehicles may also include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels obtained from resources other than petroleum). As described herein, a hybrid vehicle is a vehicle having two or more power sources, for example, an electric and gasoline-powered vehicle.

[0036] The above features and other features of the present disclosure are discussed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and other features of the present disclosure will now be described in detail with reference to certain embodiments of the present disclosure, which are illustrated in the accompanying drawings, which are given herein by way of illustration only and thus are not limiting of the present disclosure, and in which:

[0038] Figure 1 is a schematic diagram showing a control configuration for a motor drive of a conventional electric vehicle;

[0039] Figure 2 is a control configuration diagram showing a start control system for an electric vehicle according to one embodiment of the present disclosure;

[0040] Figure 3 is a flowchart showing a starting control method for an electric vehicle according to one embodiment of the present disclosure;

[0041] Figure 4 is a schematic diagram showing an example of selecting a road grip level through a display of an AVN (audio, video, navigation) system in a start control method for an electric vehicle according to an embodiment of the present disclosure;

[0042] Figure 5 is a schematic diagram showing an example of a step of guiding the execution of start control through a dashboard in a start control method for an electric vehicle according to an embodiment of the present disclosure;

[0043] Figure 6 is a graph showing a pre-motor torque application step for pre-applying torque to a motor in a start control method for an electric vehicle according to one embodiment of the present disclosure;

[0044] Figure 7 is a schematic diagram showing a state in which starting of an electric vehicle is performed faster than a vehicle without pre-motor torque through a pre-motor torque applying step in a starting control method for an electric vehicle according to one embodiment of the present disclosure; and

[0045] Figure 8 is a graph showing one example of generating a virtual engine speed when torque is pre-applied to a motor in a starting control method for an electric vehicle according to one embodiment of the present disclosure.

[0046] Reference numerals shown in the drawings include references to elements discussed further below:

[0047] It should be understood that the drawings are not necessarily drawn to scale and thus present a somewhat simplified representation of various features illustrating the basic principles of the present disclosure. The specific design features of the present disclosure disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes should be determined in part by the specific intended application and use environment.

[0048] In the drawings, reference numbers refer to the same or equivalent parts of the present disclosure throughout the several figures of the drawing. DETAILED DESCRIPTION

[0049] Reference should be made hereinafter 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 is described in conjunction with the embodiments, it should be understood that this description is not intended to limit the present disclosure to the embodiments. On the contrary, within the spirit and scope of the present disclosure as defined by the appended claims, the present disclosure is intended to cover not only the embodiments, but also various alternatives, modifications, equivalents and other embodiments.

[0050] In this specification, terms such as first and / or second may be used to describe various components, but these components are not limited by these terms. These terms are only used to distinguish one component from other components. For example, without departing from the scope of rights of the concept according to the present disclosure, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

[0051] When a controller, component, device, element, part, unit, module, etc. of the present disclosure is described as having a certain purpose or performing a certain operation, function, etc., the component, device or element should be considered as "configured to" meet the purpose or perform the operation or function in this article. Each controller, component, device, element, part, unit, module, etc. may separately embody or include a processor and a memory, such as a non-transitory computer-readable medium, as part of the device.

[0052] Hereinafter, embodiments of the present disclosure are described in detail with reference to the accompanying drawings.

[0053] Figure 2 is a control configuration diagram showing a start control system for an electric vehicle according to one embodiment of the present disclosure.

[0054] like Figure 2 As shown, an audio, video and navigation (AVN) system 110, an accelerator pedal detector 120, a brake pedal detector 130, etc. are connected to the input side of the vehicle controller 100 to achieve signal transmission. A motor controller 140 for controlling the torque of a motor 150, a sound controller 160 for outputting a virtual engine sound to a speaker 170, an instrument panel 180, etc. are connected to the output side of the vehicle controller 100.

[0055] As is well known, the AVN system 110 refers to a multimedia device in which audio, video and navigation functions are combined. The AVN system 110 includes a touch type display 112 for making selections and inputs of various menus.

[0056] Various menus for vehicle operation are displayed on the display 112 of the AVN system 110. In particular, a road grip level selection menu and a launch control activation selection menu may be displayed on the display 112.

[0057] Thus, when the driver (eg, user) touches and selects the road grip level from the menu displayed on the display 112 of the AVN system 110 , the road grip level signal may be transmitted to the vehicle controller 100 .

[0058] The road grip level is selected to optimize the wheel (tire) slip of the electric vehicle relative to the road surface during driving. Depending on the state of the road surface, such as Figure 4 As shown, the road grip level can be selected as high, or can be selected as medium or low.

[0059] In addition, when the driver touches and selects the launch control activation from the menu displayed on the display 112 of the AVN system 110 , a launch control activation signal may be transmitted to the vehicle controller 100 .

[0060] Unlike internal combustion engine vehicles, since electric vehicles do not have any elements to control engine speed and clutch, in order to optimize the wheel slip of the electric vehicle relative to the road surface, it is preferred that the road surface grip level is selected according to the state of the road surface before selecting the launch control activation.

[0061] The accelerator pedal detector 120 may be an accelerator pedal position sensor that transmits a detection signal of the amount of depression on the accelerator pedal to the vehicle controller 100. The detection signal indicates the amount by which the accelerator pedal is depressed. The brake pedal detector 130 may be a brake pedal position sensor that transmits a detection signal corresponding to the amount of depression of the brake pedal to the vehicle controller 100. In other words, the signal indicates the amount by which the brake pedal is depressed.

[0062] The vehicle controller 100 is configured to receive a road grip level signal from the AVN system 110 , receive a start control activation signal from the AVM system 110 , determine start control entry when a start control entry condition is satisfied, and execute a first stage start control.

[0063] The start control entry conditions include the following conditions.

[0064] The current vehicle driving mode may not be a boost mode or a cruise mode.

[0065] The temperature of the motor controller 140 may be equal to or less than a specific temperature (eg, 110° C. in the first motor controller for torque control of the front wheel motor, and 130° C. in the second motor controller for torque control of the rear wheel motor).

[0066] The temperature of an IGBT (Insulated Gate Bipolar Transistor) of the motor 150 may be equal to or less than a specific temperature (eg, 130° C.).

[0067] The cooling time may be longer than the reference time (eg, 2 minutes). The vehicle controller 100 determines whether all of the above-described start control entry conditions are satisfied.

[0068] As is known to all, the assist mode refers to a mode in which the maximum torque is applied to the wheels of the vehicle according to the maximum torque output of the motor for starting and driving. The cruise mode refers to a mode in which the vehicle travels at a constant speed at a preset speed. The cooling time refers to a period of time measured from the end of the previous start control.

[0069] Determining whether all of the above-mentioned start control entry conditions are satisfied is desirable to know whether the motor performance can be maximized in order to utilize the start control of the electric vehicle.

[0070] In other words, in order to utilize start-up control, it is necessary to determine whether the motor controller and the motor are in a state where maximum performance can be achieved.

[0071] For example, when the current driving mode of the vehicle is the power-assisted mode or the cruise mode, the start control entry condition is not satisfied because the motor torque is being controlled. In addition, when the temperature of the motor controller or the IGBT temperature of the motor exceeds a specific temperature, the motor performance is not maximized due to thermal reasons, so the start control entry condition is not satisfied. In addition, when the cooling time is less than a reference time (e.g., 2 minutes), the start control entry condition is not satisfied because the temperature of the motor controller or the motor may not drop below the specific temperature.

[0072] In this manner, the vehicle controller 10 is configured to determine the start control entry and execute the first stage start control when all the start control entry conditions are satisfied.

[0073] In a state where the start control entry is determined by the vehicle controller 10 and the first stage start control is executed, general electric vehicle driving may be performed until the second stage start control entry condition is satisfied.

[0074] In other words, even when the vehicle controller 10 determines that the start control is entered, while the first stage start control is being executed by the vehicle controller 10, the user can manipulate the accelerator pedal and the brake pedal in the same manner as the general electric vehicle driving mode to maintain the driving state until the second stage start control entry conditions are met.

[0075] The vehicle controller 100 is configured to determine whether a second stage start control entry condition is satisfied while determining start control entry and executing the first stage start control.

[0076] The second stage start control entry conditions include the following conditions described below.

[0077] The drive mode can be selected as Sport or Sport+.

[0078] To suppress the operation of ESC (Electronic Stability Control) as a form of vehicle dynamics control, the ESC Sport mode can be selected. Alternatively, the ESC can also be switched off.

[0079] The gearshift can be set to drive "D".

[0080] The steering angle of the steering wheel may be smaller than a certain angle (approximately 100°).

[0081] The accelerator pedal travel may exceed a certain level (eg, 95%), while at the same time, the brake pedal travel may exceed a certain level (eg, 40%).

[0082] The vehicle controller 100 determines whether all second stage start control entry conditions are satisfied.

[0083] Specifically, in order to execute the second stage start control in the state of executing the first stage start control, certain second stage start control entry conditions must be satisfied. The second stage start control entry conditions may include: i) the driver may change the driving mode to the sport mode or the sport+ mode, ii) the ESC sport mode may be selected or the ESC may be turned off so as to minimize or suppress the control of suppressing wheel slip according to the ESC on operation, iii) the steering angle of the steering wheel may be set to be lower than a specific angle so as to perform straight driving in the shift position D, and iv) the driver may keep pressing the accelerator pedal and the brake pedal simultaneously (i.e., at the same time) until the vehicle actually starts.

[0084] The vehicle controller 100 is configured to perform the second stage start control of applying the pre-motor torque to the motor 150 when all the second stage start control entry conditions are satisfied.

[0085] In other words, the vehicle controller 100 is configured to control entry into the second stage start control for applying the motor torque to the motor 150 in advance when all the second stage start control entry conditions are satisfied.

[0086] To this end, the vehicle controller 100 is configured to determine a pre-motor torque to be pre-applied to the motor using the following Formula 1 (described below) while the accelerator pedal and the brake pedal are depressed simultaneously.

[0087] (Formula 1): Pre-motor torque = max [(motor torque application map according to road grip level (vehicle speed, brake stroke), motor torque application map when the accelerator pedal and brake pedal are pressed simultaneously (vehicle speed, brake stroke)]

[0088] In Formula 1, the motor torque application map (MAP) according to the road grip level is a phenotypic mapping data preset to use the vehicle speed and the brake stroke as input variables. The motor torque application map (MAP) in the state where the accelerator pedal and the brake pedal are pressed simultaneously is a phenotypic mapping data preset to use the vehicle speed and the brake stroke as input variables.

[0089] Accordingly, when the accelerator pedal and the brake pedal are simultaneously depressed, the vehicle controller 100 determines the larger torque value of the motor torque determined from the motor torque application map according to the road grip level and the motor torque determined from the motor torque application map as the pre-motor torque to be pre-applied to the motor.

[0090] Accordingly, the vehicle controller 100 determines the pre-motor torque to be applied to the motor in advance, and then transmits the pre-motor torque value to the motor controller 140. As a result, the pre-motor torque may be applied to the motor 150 through the torque control of the motor controller 140.

[0091] In this manner, by executing the second stage start control by the vehicle controller 100 , the pre-motor torque can be applied to the motor 150 in a state where the accelerator pedal and the brake pedal are simultaneously depressed.

[0092] refer to Figure 6 , when the pre-motor torque is applied, the motor torque can be increased compared to a use case where the pre-motor torque is not applied (for example, in a use case where the motor torque is applied during normal driving). Accordingly, by pre-applying torque to the motor and wheels under the condition that the accelerator pedal and the brake pedal are simultaneously depressed, the initial starting response of the vehicle can be minimized.

[0093] Furthermore, since the pre-motor torque enables rapid initial acceleration of the electric vehicle to be increased, the time it takes for the electric vehicle to start starting after the brake pedal is released can be shortened.

[0094] For example, refer to Figure 7 , in the use case of an electric vehicle with pre-motor torque applied, initial starting after releasing the brake pedal can be performed faster than an electric vehicle without pre-motor torque applied.

[0095] When the vehicle controller 100 transmits the start control state information such as the execution of the second stage start control to the instrument cluster 180 , the instrument cluster 180 displays the guidance information for executing the start control.

[0096] For example, Figure 5 As shown, in a use case where pre-motor torque is applied to motor 150 under the condition that the accelerator pedal and the brake pedal are simultaneously depressed, if the brake pedal is released (the driver removes his foot from the brake pedal), information notifying the driver that the electric vehicle can begin to start can be displayed as a pop-up window on instrument panel 180, and if the accelerator pedal is released (the driver removes his foot from the accelerator pedal), information notifying the driver that the start control can be released can be displayed as a pop-up window on instrument panel 180.

[0097] Furthermore, the vehicle controller 100 is configured to determine a virtual engine speed when performing the second stage starting control for applying the pre-motor torque to the motor 150. The vehicle controller 100 is also configured to transmit the determined virtual engine speed to the sound controller 160.

[0098] In other words, to provide the driver with an experience similar to hearing the engine sound when the internal combustion engine vehicle is started, the vehicle controller 100 determines the virtual engine speed using the following formula 2 (described below) and sends the determined virtual engine speed to the sound controller 160.

[0099] (Formula 2): Virtual engine speed = start control setting speed ± offset

[0100] In Formula 2, when the second stage start control is executed, the + and - signs of the offset are changed at predetermined intervals.

[0101] For example, when the second stage starting control for applying the pre-motor torque is executed, the vehicle controller 100 determines the virtual engine speed to be 5500 to 6000 revolutions per minute (RPM) according to the starting control setting speed, such as Figure 8 As shown, the ripple period varies depending on the sign of the offset.

[0102] Accordingly, the sound controller 160 determines a virtual engine volume according to the virtual engine speed and outputs the determined virtual engine volume through the speaker 170. As a result, when the driver steps on the accelerator pedal just before the internal combustion engine vehicle starts, the driver can have an emotional experience similar to hearing the engine driving sound.

[0103] When executing the second stage starting control for applying the pre-motor torque, the vehicle controller 100 is configured to execute control for executing the first stage starting control again when any one of the second stage starting control entry conditions is not satisfied.

[0104] Furthermore, considering that the temperature of the motor 150 may excessively increase, the vehicle controller 100 is configured to forcibly release the second stage starting control when the time for executing the second stage starting control for applying the pre-motor torque exceeds a reference time (eg, approximately 8 seconds).

[0105] The vehicle controller 100 is configured to execute the third stage assist control mode when it is confirmed that the brake pedal is released within a reference time while the second stage start control for applying the pre-motor torque is being executed.

[0106] The power assist control mode refers to a starting drive mode in which maximum torque is applied to wheels in a state where the brake pedal is released and the accelerator pedal travel exceeds a certain level (eg, 95%) to maximize 0 to 100 kph drivability.

[0107] Specifically, the power assist control mode may be forcibly activated without a separate driver manipulation, and a maximum torque may be applied to a motor for starting a vehicle in order to maximize drag race performance.

[0108] For example, when the vehicle controller 100 performs the second stage starting control for applying the pre-motor torque, when it is confirmed that the brake pedal is released within the reference time, the power assist control mode may include the step of sending the motor maximum torque command value to the motor controller 140. The power assist control mode may also include the step of driving the motor 150 at the maximum torque for a specific period of time by torque control according to the motor maximum torque command value of the motor controller 140, and the step of applying the maximum torque to the wheels when the motor 150 is driven at the maximum torque.

[0109] The vehicle controller 100 is configured to measure the cooling time (the time measured from the end of the last start control execution) when the third stage assist control mode ends.

[0110] A start control method in a start control system for an electric vehicle according to an embodiment of the present disclosure having the above-described configuration is described below.

[0111] Figure 3 is a flowchart illustrating a starting control method for an electric vehicle according to one embodiment of the present disclosure.

[0112] First, it is determined whether the driver has selected a road grip level ( S101 ).

[0113] The road grip level is selected to optimize the wheel (tire) slip of the electric vehicle relative to the road surface during driving. Depending on the state of the road surface, such as Figure 4 As shown, the road grip level can be selected as high, or can be selected as medium or low.

[0114] Accordingly, when the driver touches and selects a road grip level from the menu displayed on the display 112 of the AVN system 110 , the selected road grip level signal may be transmitted to the vehicle controller 100 .

[0115] Then, it is determined whether the driver has selected start control activation and whether the start control entry condition is satisfied ( S102 ).

[0116] When the driver touches and selects the start control activation from the menu displayed on the display of the AVN system 110, a start control activation signal may be transmitted to the vehicle controller 100. Accordingly, the vehicle controller 100 may recognize that the start control activation is selected.

[0117] In addition, the vehicle controller 100 determines whether all start control entry conditions including the following conditions are met: 1) the current vehicle driving mode may not be the power-assisted mode or the cruise mode; 2) the temperature of the motor controller may be equal to or less than a specific temperature (for example, 110°C in the first motor controller for torque control of the front wheel motor, and 130°C in the second motor controller for torque control of the rear wheel motor); 3) the temperature of the IGBT (insulated gate bipolar transistor) of the motor may be equal to or less than a specific temperature (for example, 130°C); and 4) the cooling time may be longer than a reference time (for example, 2 minutes).

[0118] Then, when the start control activation is selected and all the above-mentioned start control entry conditions are satisfied, the start control entry is determined by the vehicle controller 100, and the first stage start control is executed (S103).

[0119] In a state where the start control entry is determined by the vehicle controller 100 and the first stage start control is executed, general electric vehicle driving may be performed until the second stage start control entry condition is satisfied.

[0120] Then, the vehicle controller 100 determines whether the second stage start control entry condition is satisfied ( S104 ).

[0121] As described above, the second stage start control entry conditions include the following conditions: 1) the driving mode may be selected as the sport mode or the sport+ mode; 2) in order to suppress the operation of the ESC (electronic stability control), the ESC sport mode may be selected, or the ESC may be turned off; 3) the gear shift may be set to drive (D); 4) the steering angle of the steering wheel may be less than a certain angle (about 100°); and 5) the accelerator pedal travel may exceed a certain level (e.g., 95%), while the brake pedal travel may exceed a certain level (e.g., 40%). The vehicle controller 100 determines whether all the second stage start control entry conditions are met.

[0122] Then, when all the second stage start control entry conditions are satisfied, the second stage start control of applying the pre-motor torque to the motor 150 is performed by the vehicle controller 100 and a virtual engine speed is created ( S105 ).

[0123] To this end, the vehicle controller 100 determines a pre-motor torque to be pre-applied to the motor 150 using Equation 1 in a state in which the accelerator pedal and the brake pedal are simultaneously depressed.

[0124] Specifically, when the accelerator pedal and the brake pedal are simultaneously depressed, the vehicle controller 100 determines the larger torque value of the motor torque determined from the motor torque application map according to the road grip level and the motor torque determined from the motor torque application map as the pre-motor torque to be pre-applied to the motor 150.

[0125] Accordingly, the vehicle controller 100 determines the pre-motor torque to be applied to the motor in advance, and then sends the pre-motor torque value to the motor controller 140. As a result, the pre-motor torque can be applied to the motor 150 through the torque control of the motor controller 140 in a state where the accelerator pedal and the brake pedal are simultaneously depressed.

[0126] Accordingly, if Figure 6 As shown, when the pre-motor torque is applied, the motor torque can be increased compared to a use case where the pre-motor torque is not applied (e.g., when the motor torque is applied during normal driving). In addition, since the pre-motor torque is applied to the motor and the wheels in advance under the condition that the accelerator pedal and the brake pedal are simultaneously depressed, the initial starting response of the vehicle can be minimized. In addition, since the pre-motor torque can increase the rapid initial acceleration of the electric vehicle, the time it takes for the electric vehicle to start after the brake pedal is released can be shortened.

[0127] The vehicle controller 100 performs the second stage starting control for applying the pre-motor torque to the motor 150 , determines a virtual engine speed, and transmits the determined virtual engine speed to the sound controller 160 .

[0128] In other words, in order to provide the driver with an experience similar to hearing the engine sound when the internal combustion engine vehicle is started, the vehicle controller 100 determines the virtual engine speed using Formula 2 and sends the determined virtual engine speed to the sound controller 160 .

[0129] Accordingly, the sound controller 160 determines the virtual engine volume according to the virtual engine speed, and outputs the determined virtual engine volume through the speaker 170. As a result, when the driver steps on the accelerator pedal just before the internal combustion engine vehicle starts, the driver can have an emotional experience similar to hearing the engine driving sound. Therefore, the driver's demand for high-performance vehicles can be met.

[0130] Then, the vehicle controller 100 determines whether the brake pedal is released and the accelerator pedal stroke exceeds a certain level (eg, 95%) at a vehicle speed of 0 kph ( S106 ).

[0131] As a result of determining that the brake pedal is released and the accelerator pedal stroke exceeds a certain level (eg, 95%), the third stage assist control mode is executed by the vehicle controller 100 to apply the maximum torque to the wheels ( S107 ).

[0132] The power assist control mode executed in a state where the brake pedal is released and the accelerator pedal travel exceeds a certain level (e.g., 95%) can be forcibly activated without a separate driver manipulation to maximize the drivability from 0 to 100 kph. In addition, the power assist control mode can apply maximum torque to the motor to maximize the drag race performance for starting the vehicle.

[0133] For example, when the vehicle controller 100 performs the second stage starting control for applying the pre-motor torque, when it is confirmed that the brake pedal is released within the reference time, the power assist control mode may include the step of sending the motor maximum torque command value to the motor controller 140. The boost motor control mode may also include the step of driving the motor 150 at the maximum torque for a specific period of time by torque control according to the motor maximum torque command value of the motor controller 140, and the step of applying the maximum torque to the wheels when the motor 150 is driven at the maximum torque.

[0134] The vehicle controller 100 determines whether the time for executing the second stage starting control for applying the pre-motor torque exceeds a reference time (e.g., approximately 8 seconds) (S108). When it is confirmed that the time for executing the second stage starting control for applying the pre-motor torque exceeds the reference time (S108), considering that the temperature of the motor may be excessively increased, the starting control is forcibly released.

[0135] In this manner, when it is confirmed that the brake pedal is released within the reference time while performing the second stage starting control for applying the pre-motor torque, the vehicle controller 100 performs the third stage assist control mode to apply the maximum torque to the wheels.

[0136] Accordingly, the present disclosure provides the following effects.

[0137] First, by maximizing acceleration in the initial stage of starting the electric vehicle from a stationary state, high performance of the electric vehicle can be achieved.

[0138] Second, by shortening the time to reach maximum acceleration when starting an electric vehicle from a standstill and maximizing acceleration, drivers' demands for high-performance vehicles can be met.

[0139] Third, under the condition that the brake pedal and the accelerator pedal are pressed simultaneously before the electric vehicle actually starts, the response at the initial start of the electric vehicle can be minimized by applying torque to the motor in advance. As a result, due to the rapid initial acceleration of the electric vehicle, the time it takes for the electric vehicle to start after the brake pedal is released can be shortened, thereby meeting the driver's demand for high-performance vehicles.

[0140] Fourth, when torque is pre-applied to the motor under the condition that the brake pedal and the accelerator pedal are simultaneously depressed before the actual start of the electric vehicle, since the sound controller outputs the engine sound based on the virtual engine speed signal and the volume signal, the driver's demand for a high-performance vehicle can be met.

[0141] The present disclosure has been described in detail with reference to the embodiments of the present disclosure. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A starting control system for an electric vehicle, the starting control system comprising: an audio, video and navigation (AVN) system, the AVN system being configured to select a road grip level and launch control activation; an accelerator pedal detector configured to detect an amount of depression of an accelerator pedal; a brake pedal detector configured to detect a depression amount of a brake pedal; as well as Vehicle controller, Wherein, based on the start control activation signal from the AVN system, the detection signal of the accelerator pedal detector and the detection signal of the brake pedal detector, the vehicle controller is configured to: When the first stage start control entry condition is met, the first stage start control is executed. When a second-stage start control condition is satisfied in a state where the first-stage start control is executed, a second-stage start control is executed to apply a pre-motor torque to the motor, and When the brake pedal is released in a state where the second stage start control is executed, a third stage assist control mode is executed.

2. The start control system according to claim 1, wherein: The vehicle controller is further configured to: execute the first stage start control when all the first stage start control entry conditions are satisfied, and Among them, the first stage starting control entry conditions include: i) the current driving mode of the vehicle is not in power-assisted mode or cruise mode, ii) the temperature of the motor controller is equal to or less than a specific temperature, iii) the temperature of the insulated gate bipolar transistor (IGBT) of the motor is equal to or less than a specific temperature, and iv) the cooling time is longer than the reference time.

3. The starting control system according to claim 1, wherein: The vehicle controller is further configured to: execute the second stage start control when all second stage start control entry conditions are satisfied, and Among them, the second stage starting control entry conditions include: i) the driving mode is selected as the sport mode or the sport+ mode, ii) the electronic stability control (ESC) is turned off, iii) the gear shift is set to drive (D), iv) the steering angle of the steering wheel is less than a specific angle, and v) the accelerator pedal travel exceeds a specific level, and the brake pedal travel exceeds a specific level at the same time.

4. The starting control system according to claim 1, wherein: The vehicle controller is also configured to, when the accelerator pedal and the brake pedal are simultaneously depressed, determine a larger torque value between a motor torque determined from a motor torque application map according to the road grip level and a motor torque determined from a motor torque application map as the pre-motor torque to be pre-applied to the motor.

5. The starting control system according to claim 4, wherein: When the pre-motor torque determined by the vehicle controller is transmitted to a motor controller, the pre-motor torque is applied to the motor through torque control of the motor controller.

6. The start control system according to claim 1, further comprising: An instrument panel is configured to display guidance information for start control execution based on the start control state information received from the vehicle controller.

7. The starting control system according to claim 1, wherein: The vehicle controller is further configured to determine a virtual engine speed when the second stage start control is performed, and transmit the determined virtual engine speed to the sound controller.

8. The start control system according to claim 7, wherein: The sound controller is configured to determine a virtual engine volume according to the virtual engine speed, and output the determined virtual engine volume through a speaker.

9. The starting control system according to claim 1, wherein: The vehicle controller is further configured to, when the second stage start control for applying the pre-motor torque is executed, execute control for executing the first stage start control again when a second stage start control entry condition is not satisfied.

10. The start control system according to claim 1, wherein: The vehicle controller is further configured to forcibly release the second stage starting control when a time for executing the second stage starting control for applying the pre-motor torque exceeds a reference time.

11. The starting control system according to claim 1, wherein: The vehicle controller is further configured to, when the second stage starting control for applying the pre-motor torque is executed, execute a third stage assist control mode upon confirming that the brake pedal is released within a reference time.

12. The start control system according to claim 11, wherein: The vehicle controller is further configured to measure a cooling time at the end of the third stage power assist control mode.

13. A starting control method for an electric vehicle, the starting control method comprising the following steps: determining, by a vehicle controller, whether a road grip level is selected; determining, by the vehicle controller, whether launch control activation is selected and whether a first stage launch control entry condition is satisfied; executing, by the vehicle controller, a first stage start control when the road grip level and the start control activation are selected and the first stage start control entry condition is satisfied; executing, by the vehicle controller, a second stage start control for applying a pre-motor torque to a motor of the electric vehicle when a second stage start control entry condition is satisfied and when the first stage start control is executed; and When the brake pedal is released and the second stage start control is executed, a third stage assist control mode is executed by the vehicle controller.

14. The startup control method according to claim 13, wherein: When all the first stage start control entry conditions are satisfied, the first stage start control is executed by the vehicle controller, and Among them, the first stage starting control entry conditions include: i) the current driving mode of the vehicle is not in power-assisted mode or cruise mode, ii) the temperature of the motor controller is equal to or less than a specific temperature, iii) the temperature of the insulated gate bipolar transistor (IGBT) of the motor is equal to or less than a specific temperature, and iv) the cooling time is longer than the reference time.

15. The startup control method according to claim 13, wherein: When all the second stage start control entry conditions are satisfied, the second stage start control is executed by the vehicle controller, and Among them, the second stage starting control entry conditions include: i) the driving mode is selected as the sport mode or the sport+ mode, ii) the electronic stability control (ESC) is turned off, iii) the gear shift is set to drive (D), iv) the steering angle of the steering wheel is less than a specific angle, and v) the accelerator pedal travel exceeds a specific level, and the brake pedal travel exceeds a specific level at the same time.

16. The startup control method according to claim 13, wherein: Executing the second stage starting control includes: determining, by the vehicle controller, a larger torque value of a motor torque determined from a motor torque application map according to the road grip level and a motor torque determined from a motor torque application map as the pre-motor torque in a state where an accelerator pedal and a brake pedal are simultaneously depressed; sending, by the vehicle controller, the determined pre-motor torque to a motor controller; and The pre-motor torque is applied to the motor through torque control of the motor controller.

17. The startup control method according to claim 13, further comprising the following steps: Based on the start control state information received from the vehicle controller, guidance information for executing the start control is displayed through an instrument panel.

18. The startup control method according to claim 13, further comprising the following steps: When the second stage starting control is executed, a virtual engine speed is determined by the vehicle controller; sending, by the vehicle controller, the virtual engine speed to a sound controller; determining, by the sound controller, a virtual engine volume according to the virtual engine speed; as well as The determined virtual engine volume is output via a speaker.

19. The startup control method according to claim 13, wherein: When it is confirmed that the brake pedal is released within a reference time, the third stage assist control mode is executed, and the second stage start control for applying the pre-motor torque is executed.

20. The startup control method according to claim 13, further comprising the following steps: When the second stage start control for applying the pre-motor torque is executed, when any one of the second stage start control entry conditions is not satisfied, executing, by the vehicle controller, control for executing the first stage start control again; when a time for executing the second stage start control for applying the pre-motor torque exceeds a reference time, forcibly releasing the second stage start control by the vehicle controller; and When the third stage power assist control mode ends, a cooling time is measured by the vehicle controller.

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