Electric vehicles

Abstract

When the clutch pedal is pressed while regenerative braking is being performed on an electric vehicle, the system prevents or suppresses the driver from pressing the brake pedal further, while suppressing changes in the vehicle's braking force. [Solution] The electric vehicle comprises an electric motor connected to the drive wheels via a clutch, a stroke sensor for detecting the clutch stroke, a braking device, and one or more electronic control units. The braking device is configured to apply regenerative braking torque to the drive wheels by controlling the electric motor and to apply friction braking torque to the drive wheels by supplying brake hydraulic pressure to the wheel cylinders of the drive wheels. When the clutch pedal is pressed during regenerative braking, in which regenerative braking torque is applied to the drive wheels, one or more electronic control units perform a hydraulic pressure increase process to control the braking device so that brake hydraulic pressure corresponding to the clutch stroke detected by the stroke sensor is applied to the wheel cylinders.

Description

[Technical Field]

[0001] The present disclosure relates to an electric vehicle including an electric motor connected to drive wheels via a clutch. [Background Art]

[0002] Patent Document 1 discloses a brake control device that performs regenerative cooperative brake control for an electric vehicle. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2011-183961 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In an electric vehicle including an electric motor connected to drive wheels via a clutch, if regenerative braking torque no longer acts on the drive wheels as a result of the clutch pedal being depressed during execution of regenerative braking, the driver is required to further depress the brake pedal.

[0005] The present disclosure has been made in view of the problems described above, and an object of the present disclosure is to provide an electric vehicle capable of suppressing a change in vehicle braking force while avoiding or suppressing the need for the driver to further depress the brake pedal when the clutch pedal is depressed during execution of regenerative braking in the electric vehicle. [Means for Solving the Problem]

[0006] The electric vehicle according to this disclosure comprises an electric motor, a stroke sensor, a braking system, and one or more electronic control units. The electric motor is connected to the drive wheels via a clutch. The stroke sensor detects the clutch stroke, which is the amount the clutch pedal is pressed to operate the clutch. The braking system is configured to apply regenerative braking torque to the drive wheels by controlling the electric motor and to apply friction braking torque to the drive wheels by supplying brake hydraulic pressure to the wheel cylinders of the drive wheels. When the clutch pedal is pressed during regenerative braking, in which regenerative braking torque is applied to the drive wheels, one or more electronic control units perform a hydraulic pressure increase process to control the braking system so that brake hydraulic pressure corresponding to the clutch stroke detected by the stroke sensor is applied to the wheel cylinders. [Effects of the Invention]

[0007] According to this disclosure, when the clutch pedal is depressed during regenerative braking, it is possible to add brake hydraulic pressure of an appropriate magnitude to correspond to the decrease in regenerative braking torque corresponding to the clutch stroke. This makes it possible to suppress changes in vehicle braking force while avoiding or suppressing the driver from pressing the brake pedal further. [Brief explanation of the drawing]

[0008] [Figure 1] This figure schematically shows an example of the configuration of an electric vehicle according to an embodiment. [Figure 2] This diagram illustrates the basic configuration of regenerative braking control. [Figure 3] This is a diagram illustrating the outline of the hydraulic pressure increase process according to the embodiment. [Figure 4] This flowchart shows the details of the hydraulic pressure increase process according to the embodiment. [Figure 5] This graph shows the relationship between clutch stroke and transmission efficiency. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described with reference to the attached drawings.

[0010] 1. Configuration of electric vehicles Figure 1 is a schematic diagram showing an example of the configuration of an electric vehicle 1 according to this embodiment. The electric vehicle 1 (hereinafter also simply referred to as vehicle 1) is, for example, a battery electric vehicle (BEV), but may also be a hybrid electric vehicle (HEV) or a fuel cell electric vehicle (FCEV). Vehicle 1 has drive wheels 2. The drive wheels 2 are, for example, the rear wheels of vehicle 1 (more specifically, the left and right rear wheels), but may also be the front wheels (more specifically, the left and right front wheels), or both the front and rear wheels.

[0011] Vehicle 1 is equipped with an electric motor 11. The electric motor 11 is powered by electricity supplied from a battery (not shown) and drives vehicle 1. For example, the electric motor 11 is configured as an electric drive unit 10 together with an inverter 12 for driving the electric motor 11. The inverter 12 is controlled based on commands from the drive ECU 40, which will be described later.

[0012] The electric motor 11 is connected to the drive wheels 2 via a clutch 3. More specifically, the electric motor 11 is connected to a manual transmission (MT) 4 via a clutch 3. The manual transmission 4 is connected to the drive wheels 2 via, for example, a propeller shaft 5, a differential gear 6, and a drive shaft 7. The clutch 3 is engaged / disengaged by the operation of a clutch pedal 8 by the driver of the vehicle 1.

[0013] Vehicle 1 is equipped with a braking system 20. The braking system 20 is configured to apply a regenerative braking torque Trb to the drive wheels 2 by controlling an electric motor 11, and to apply a friction braking torque Tfb to the drive wheels 2 by supplying brake hydraulic pressure P to the wheel cylinders 23 of the drive wheels 2.

[0014] The braking system 20 includes a brake pedal 9, a brake actuator 21, hydraulic piping 22, and a brake mechanism (only the wheel cylinders 23 are shown). The brake mechanism is located on each wheel of the vehicle 1, including the drive wheels 2. The brake mechanism, along with the wheel cylinders 23, includes, for example, brake pads and brake discs. The brake actuator 21 distributes hydraulic pressure generated by a master cylinder (not shown) in response to the depression of the brake pedal 9 to each wheel cylinder 23 via the hydraulic piping 22. The wheel cylinders 23 act in response to the supplied hydraulic pressure (referred to as "brake hydraulic pressure P"), as a result of the brake pads being pressed against the brake discs and a friction braking torque Tfb being applied to the drive wheels 2 (more specifically, each wheel including the drive wheels 2).

[0015] Furthermore, in relation to applying a regenerative braking torque Trb to the drive wheels 2, the electric motor 11 and inverter 12 function as part of the braking system 20. That is, the drive ECU 40 controls the inverter 12 in response to a request from the brake ECU 30, so that the electric motor 11 functions as a generator that generates a negative motor torque Tm, which is the basis of the regenerative braking torque Trb. The magnitude of this motor torque Tm is controlled by the inverter 12. The power generated by the electric motor 11 is stored in the battery. A regenerative braking torque Trb corresponding to the motor torque Tm is applied to the drive wheels 2.

[0016] Vehicle 1 includes, as an example of the "one or more electronic control units (ECUs)" relating to this disclosure, a brake ECU 30 and a drive ECU 40. The brake ECU 30, together with the braking device 20, constitutes the brake system of Vehicle 1. The drive ECU 40, together with the electric drive unit 10, constitutes the drive system of Vehicle 1. Note that each of the brake ECU 30 and the drive ECU 40 may be a combination of multiple ECUs.

[0017] The brake ECU 30 includes a processor and a storage device. The brake ECU 30 acquires information from various sensors attached to the vehicle 1. The various sensors referred to herein include, for example, a brake pedal sensor 31 together with an unillustrated wheel speed sensor and a longitudinal acceleration sensor. The wheel speed sensors are arranged corresponding to each wheel including the drive wheels 2. The longitudinal acceleration sensor detects acceleration of the vehicle 1 in the longitudinal direction. The brake pedal sensor 31 detects an operation state (operation amount or operation force) of the brake pedal 9 by a driver of the vehicle 1. More specifically, the operation amount referred to herein is the depression amount of the brake pedal 9, and the operation force is the depression force applied to the brake pedal 9.

[0018] The brake ECU 30 controls the friction braking torque Tfb by controlling the brake actuator 21 based on information from the various sensors described above. The brake ECU 30 is also capable of communicating with a drive ECU 40, and outputs a requested regenerative braking torque Trbreq to the drive ECU 40 during regenerative braking as described later. Various control programs are stored in the storage device. The processor reads out and executes the control programs from the storage device. This realizes various processes relating to braking of the vehicle 1 by the brake ECU 30, including the "hydraulic pressure increase process" described later.

[0019] The drive ECU 40 includes a processor and a storage device. The drive ECU 40 acquires information from various sensors attached to the vehicle 1. The various sensors referred to herein include, for example, the aforementioned wheel speed sensor and longitudinal acceleration sensor, an unillustrated accelerator position sensor and motor rotation angle sensor (resolver), as well as a stroke sensor 41. The accelerator pedal sensor detects the depression amount of an accelerator pedal (not illustrated) by a driver of the vehicle 1. The motor rotation angle sensor detects the rotation angle of the electric motor 11. The drive ECU 40 calculates the rotational speed of the electric motor 11 from the detected rotation angle. The stroke sensor 41 detects the depression amount (clutch stroke S) of the clutch pedal 8 by a driver of the vehicle 1.

[0020] The drive ECU 40 outputs a requested motor torque Tmreq for controlling the electric motor 11 to the inverter 12 based on information from the various sensors described above. Various control programs are stored in the storage device. The processor reads the control program from the storage device and executes it. This realizes various processes related to the driving of the vehicle 1 by the drive ECU 40, and further the "hydraulic pressure increase process" described later. In addition, the requested motor torque Tmreq output from the drive ECU 40 to the inverter 12 includes a negative requested motor torque Tmreq calculated in accordance with the requested regenerative braking torque Trbreq from the brake ECU 30 during regenerative braking.

[0021] 2. Regenerative cooperative brake control 2-1. Basic Configuration FIG. 2 is a diagram for explaining the basic configuration of regenerative cooperative brake control.

[0022] When the driver depresses the brake pedal 9, the brake ECU 30 receives the operating state (operation amount or operation force) of the brake pedal 9 from the brake pedal sensor 31. Then, the brake ECU 30 calculates a requested vehicle braking torque Tbreq based on the received operating state. The requested vehicle braking torque Tbreq is a requested value for the overall braking torque Tb of the vehicle 1.

[0023] On the other hand, the drive ECU 40 calculates a "regenerative limit torque Trl" and transmits the calculated regenerative limit torque Trl to the brake ECU 30 (see FIG. 2). More specifically, the drive ECU 40 calculates the regenerative limit torque Trl based on, for example, the rotation speed of the electric motor 11 and the remaining state of charge (SOC) of the battery. The calculation and transmission of this regenerative limit torque Trl are executed, for example, during braking of the vehicle 1 accompanying detection of depression of the brake pedal 9 by the brake pedal sensor 31.

[0024] The brake ECU 30 distributes the calculated required vehicle braking torque Tbreq to the required regenerative braking torque Trbreq and the required friction braking torque Tfbreq. In this process, the brake ECU 30 distributes the required vehicle braking torque Tbreq to the required regenerative braking torque Trbreq, with the regenerative limit torque Trl received from the drive ECU 40 as the upper limit. That is, the brake ECU 30 calculates the required regenerative braking torque Trbreq within a range that does not exceed the regenerative limit torque Trl. Then, the brake ECU 30 distributes the remainder obtained by subtracting the required regenerative braking torque Trbreq from the required vehicle braking torque Tbreq to the required friction braking torque Tfbreq.

[0025] More specifically, if the required vehicle braking torque Tbreq is higher than the regenerative limit torque Trl, the brake ECU 30 calculates a required regenerative braking torque Trbreq that is equal to the regenerative limit torque Trl. On the other hand, if the required vehicle braking torque Tbreq is less than or equal to the regenerative limit torque Trl, the brake ECU 30 calculates a required regenerative braking torque Trbreq that is equal to the required vehicle braking torque Tbreq. In other words, all of the required vehicle braking torque Tbreq is allocated to the required regenerative braking torque Trbreq. Therefore, if the required vehicle braking torque Tbreq is less than or equal to the regenerative limit torque Trl, the required vehicle braking torque Tbreq is not allocated to the required friction braking torque Tfbreq. In other words, the required friction braking torque Tfbreq becomes 0.

[0026] The brake ECU 30 transmits the calculated required regenerative braking torque Trbreq to the drive ECU 40 (see Figure 2). The brake ECU 30 also controls the brake actuator 21 so that the calculated required friction braking torque Tfbreq is generated.

[0027] The drive ECU 40 calculates the required motor torque Tmreq from the required regenerative braking torque Trbreq received from the brake ECU 30. More specifically, the drive ECU 40 calculates the required motor torque Tmreq considering constraints on the drive system (e.g., the gear ratio between the electric motor 11 and the drive wheels 2, and the transmission efficiency K of the clutch 3). The drive ECU 40 then transmits the calculated required motor torque Tmreq to the inverter 12 (see Figure 2). As a result, the electric motor 11 is controlled by the inverter 12 to generate the required motor torque Tmreq corresponding to the required regenerative braking torque Trbreq.

[0028] 2-2. Hydraulic increase process based on clutch stroke In electric vehicles equipped with an electric motor connected to the drive wheels via a clutch, as described in electric vehicle 1 above, if the clutch pedal is pressed during regenerative braking and the regenerative braking torque ceases to act on the drive wheels, the driver is required to press the brake pedal further.

[0029] Therefore, in this embodiment, when the clutch pedal 8 is pressed during regenerative braking in which a regenerative braking torque Trb is applied to the drive wheel 2 (see, for example, Figure 2), one or more ECUs of the vehicle 1 perform the following hydraulic pressure increase process. According to the hydraulic pressure increase process, the braking device 20 is controlled so that a brake hydraulic pressure P corresponding to the clutch stroke S detected by the stroke sensor 41 is applied to the wheel cylinder 23 of the drive wheel 2.

[0030] The addition of brake hydraulic pressure P through the hydraulic pressure increase process is performed, for example, in a situation where friction braking torque Tfb is applied to the drive wheels 2 along with regenerative braking torque Trb, so as to increase the friction braking torque Tfb. Alternatively, the addition of brake hydraulic pressure P is performed in a situation where friction braking torque Tfb is applied to the drive wheels 2, so as to a situation where only regenerative braking torque Trb is applied.

[0031] More specifically, as shown in the flowchart in Figure 4 described later, the brake hydraulic pressure P added by the hydraulic pressure increase process when the clutch stroke S is large may be controlled to be larger than when the clutch stroke S is small.

[0032] Figure 3 is a diagram illustrating the overview of the hydraulic pressure increase process according to this embodiment. Here, the additions made to the basic configuration of the regenerative cooperative brake control shown in Figure 2 are explained. In this embodiment, the hydraulic pressure increase process is performed by the cooperation of the brake ECU 30 and the drive ECU 40, which correspond to the "one or more ECUs" mentioned above, as an example.

[0033] First, the hydraulic pressure increase process performed on the drive ECU 40 will be explained. As shown in Figure 3, when the clutch pedal 8 is pressed by the driver while regenerative braking is being performed, the drive ECU 40 receives (acquires) the clutch stroke S from the stroke sensor 41. The drive ECU 40 then corrects the regenerative limit torque Trl according to the received clutch stroke S. In other words, the drive ECU 40 calculates the corrected regenerative limit torque Trlc according to the clutch stroke S (see step S104 below for details). The drive ECU 40 transmits the calculated corrected regenerative limit torque Trlc to the brake ECU 30.

[0034] Next, the hydraulic pressure increase process performed on the brake ECU 30 will be described. As shown in Figure 3, the brake ECU 30 distributes the requested vehicle braking torque Tbreq into the requested regenerative braking torque Trbreq and the requested friction braking torque Tfbreq, with the modified regenerative limit torque Trlc received from the drive ECU 40 as the upper limit.

[0035] Figure 4 is a flowchart detailing the hydraulic pressure increase process according to this embodiment. This flowchart process is initiated, for example, when the driver's depression of the brake pedal 9 is detected. This flowchart process may be repeatedly executed at a predetermined control cycle during braking of the vehicle 1.

[0036] In step S100, the drive ECU 40 determines whether or not the clutch stroke S when the clutch pedal 8 is depressed has been received from the stroke sensor 41. If the clutch stroke S has been received (step S100; Yes), the process proceeds to step S102.

[0037] In step S102, the drive ECU 40 calculates the transmission efficiency K of the clutch 3 corresponding to the received clutch stroke S. Figure 5 is a graph showing the relationship between the clutch stroke S and the transmission efficiency K. The memory device of the drive ECU 40 stores relational information (e.g., maps, relational formulas) showing the relationship between the clutch stroke S and the transmission efficiency K as shown in Figure 5. The clutch stroke S takes a value of 0 when the clutch pedal 8 is not pressed and increases as the amount of depression increases. The transmission efficiency K basically decreases as the clutch stroke S increases. More specifically, in the example shown in Figure 5, the transmission efficiency K takes its maximum value in the range R1 of the clutch stroke S from 0 to S1. Then, in the range R2 from S1 to S2 (>S1), the transmission efficiency K decreases from the maximum value to 0. S2 corresponds to the minimum value of the clutch stroke S at which the clutch 3 is fully disengaged. From the relational information described above, the drive ECU 40 calculates (acquires) the transmission efficiency K corresponding to the clutch stroke S received in step S100. Within range R2 (see Figure 5), the transmission efficiency K is calculated to decrease as the clutch stroke S increases. The process then proceeds to step S104.

[0038] In step S104, the drive ECU 40 calculates the corrected regenerative limit torque Trlc by multiplying the transmission efficiency K calculated in step S102 by the regenerative limit torque Trl (base value). As already explained, the regenerative limit torque Trl (base value) can be calculated, for example, based on the rotational speed of the electric motor 11 and the remaining charge of the battery. According to the corrected regenerative limit torque Trlc, in the range R2 (see Figure 5), the regenerative limit torque Trl is corrected to be lower as the clutch stroke S increases. Thus, the process in step S104 calculates the corrected regenerative limit torque Trlc that takes into account the transmission efficiency K of the clutch 3.

[0039] In step S106, following step S104, the drive ECU 40 transmits the calculated modified regenerative limit torque Trlc to the brake ECU 30.

[0040] In step S200, the brake ECU 30 determines whether or not it has received the corrected regenerative limit torque Trlc from the drive ECU 40. If the corrected regenerative limit torque Trlc is received (step S200; Yes), the process proceeds to step S202.

[0041] In step S202, the brake ECU 30 calculates the required vehicle braking torque Tbreq based on the operating state of the brake pedal sensor 31. Then, using the received modified regenerative limit torque Trlc as an upper limit, the brake ECU 30 distributes the required vehicle braking torque Tbreq into the required regenerative braking torque Trbreq and the required friction braking torque Tfbreq using the method described in Section 2-1 above.

[0042] As a result, within range R2 (see Figure 5), the required regenerative braking torque Trbreq will be distributed in a manner that follows the same trend as the corrected regenerative limit torque Trlc (i.e., it will decrease as the clutch stroke S increases), as can be seen from the supplementary explanation below. In other words, if the corrected regenerative limit torque Trlc is calculated to decrease as the clutch stroke S increases when the required vehicle braking torque Tbreq is higher than the regenerative limit torque Trl (base value), then the required regenerative braking torque Trbreq will also be distributed in a manner that decreases as the clutch stroke S increases. Furthermore, even when the required vehicle braking torque Tbreq is less than or equal to the regenerative limit torque Trl (base value), if the corrected regenerative limit torque Trlc is calculated to decrease as the clutch stroke S increases, the corrected regenerative limit torque Trlc will tend to fall below the required vehicle braking torque Tbreq. Furthermore, if the corrected regenerative limit torque Trlc becomes lower than the required vehicle braking torque Tbreq, the required regenerative braking torque Trbreq, which is allocated from the required vehicle braking torque Tbreq, will be limited (i.e., reduced) by the corrected regenerative limit torque Trlc.

[0043] On the other hand, the required friction braking torque Tfbreq is distributed in a manner that tends to increase as the clutch stroke S increases, contrary to the required regenerative braking torque Trbreq mentioned above. In addition, when the clutch stroke S is S2 (see Figure 5) or greater, the modified regenerative limit torque Trlc is 0, so the required regenerative braking torque Trbreq takes a value of 0, and the required friction braking torque Tfbreq becomes equal to the required vehicle braking torque Tbreq. The process then proceeds to step S204.

[0044] In step S204, the brake ECU 30 transmits the requested regenerative braking torque Trbreq to the drive ECU 40. The brake ECU 30 also commands the brake actuator 21 to use the calculated requested friction braking torque Tfbreq. As described above, within the range R2 (see Figure 5), the requested friction braking torque Tfbreq is distributed such that it tends to increase as the clutch stroke S increases. Therefore, the brake actuator 21 (braking device 20) is controlled such that the brake hydraulic pressure P applied based on the requested friction braking torque Tfbreq distributed in this way is greater when the clutch stroke S is large compared to when the clutch stroke S is small.

[0045] Furthermore, in step S108, following step S106, the drive ECU 40 determines whether or not it has received a requested regenerative braking torque Trbreq from the brake ECU 30. If the requested regenerative braking torque Trbreq is received (step S108; Yes), the process proceeds to step S110.

[0046] In step S110, the drive ECU 40 calculates the requested motor torque Tmreq from the requested regenerative braking torque Trbreq received from the brake ECU 30, as already described, and transmits the calculated requested motor torque Tmreq to the inverter 12. As a result, the electric motor 11 is controlled by the inverter 12 to generate a negative requested motor torque Tmreq corresponding to the requested regenerative braking torque Trbreq.

[0047] As described above, the hydraulic pressure increase process according to this embodiment makes it possible to add brake hydraulic pressure P of an appropriate magnitude corresponding to the decrease in regenerative braking torque Trb corresponding to the clutch stroke S when the clutch pedal 8 is pressed during regenerative braking. This makes it possible to suppress changes in vehicle braking force (vehicle braking torque Tb) while avoiding or suppressing the driver from pressing the brake pedal 9 further.

[0048] More specifically, the torque transmitted by the clutch 3 when the clutch pedal 8 is depressed is proportional to the transmission efficiency K, and the transmission efficiency K changes according to the clutch stroke S (see Figure 5). Therefore, the amount of decrease in regenerative braking torque Trb associated with the depression of the clutch pedal 8 will differ depending on the clutch stroke S. Consequently, if a method is used in which the brake hydraulic pressure P is uniformly increased by a predetermined fixed value in response to the depression of the clutch pedal 8 without considering the magnitude of the clutch stroke S (comparative example), it may be difficult to appropriately suppress changes in vehicle braking force regardless of the clutch stroke S. For example, if the clutch stroke S is short (e.g., a value close to S1 in Figure 5), the brake hydraulic pressure P may become excessive depending on the magnitude of the fixed value. As a result, the driver may be required to operate the brake pedal 9 further. In contrast, with the hydraulic pressure increase process according to this embodiment, by adding brake hydraulic pressure P according to the clutch stroke S, it is possible to appropriately suppress changes in vehicle braking force compared to the comparative example above. [Explanation of Symbols]

[0049] 1 Electric vehicle, 2 Drive wheels, 3 Clutch, 8 Clutch pedal, 9 Brake pedal, 11 Electric motor, 12 Inverter, 20 Braking system, 23 Wheel cylinder, 31 Brake pedal sensor, 41 Stroke sensor, 30 Brake ECU, 40 Drive ECU

Claims

1. An electric motor connected to the drive wheels via a clutch, A stroke sensor detects the clutch stroke, which is the amount the clutch pedal is pressed to operate the clutch, A braking device configured to apply regenerative braking torque to the drive wheel by controlling the electric motor and to apply frictional braking torque to the drive wheel by supplying brake hydraulic pressure to the wheel cylinder of the drive wheel, One or more electronic control units, Equipped with, When the clutch pedal is pressed during regenerative braking, in which the regenerative braking torque is applied to the drive wheels, the one or more electronic control units perform a hydraulic pressure increase process to control the braking device so that the brake hydraulic pressure corresponding to the clutch stroke detected by the stroke sensor is applied to the wheel cylinder. Electric vehicle.

2. The electric vehicle according to claim 1, The one or more electronic control units control the braking device such that the brake hydraulic pressure added by the hydraulic pressure increase process is greater when the clutch stroke is large compared to when the clutch stroke is small. Electric vehicle.

3. The electric vehicle according to claim 2, The one or more electronic control units described above are: The required vehicle braking torque is calculated based on the brake pedal operation state. The required vehicle braking torque is allocated to the required regenerative braking torque, with the regenerative limit torque as the upper limit, and the remainder obtained by subtracting the required regenerative braking torque from the required vehicle braking torque is allocated to the required friction braking torque. The hydraulic pressure increase process includes modifying the regenerative limit torque such that it becomes lower as the clutch stroke detected by the stroke sensor during the execution of the regenerative braking increases. Electric vehicle.

4. The electric vehicle according to claim 3, The hydraulic pressure increase process includes calculating the transmission efficiency based on the relationship between the clutch stroke and the transmission efficiency of the clutch such that it decreases as the clutch stroke increases, and modifying the regenerative limit torque such that it decreases as the clutch stroke increases by multiplying the calculated transmission efficiency by the base value of the regenerative limit torque. vehicle.

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