Coasting feedback adaptive degradation control method and control system for electric vehicles

Abstract

The present invention provides a coasting feedback adaptive degradation control method and control system for an electric vehicle, and relates to the technical field of vehicle energy recovery. The coasting feedback adaptive degradation control method for an electric vehicle of the present invention comprises: collecting status data for indicating the state of the vehicle; judging whether the vehicle satisfies a first condition according to the status data; judging whether the vehicle satisfies a second condition when the vehicle satisfies the first condition; and controlling the coasting feedback level of the vehicle to be reduced by one level or maintained at the lowest level when the vehicle satisfies the second condition. Among them, the first condition is that the vehicle is in a drivable state, the vehicle is in D / R gear, the reference speed of the vehicle exceeds a predetermined value, the vehicle is not braked, and the vehicle is in a feedback state. The second condition is selected from one of the following: the estimated ground adhesion coefficient is less than a preset value and exceeds a first preset time, the wheel tends to be locked, or the ABS is activated. The present invention can reasonably utilize road adhesion to feedback power generation, the driving feel is smoother, and the pure electric endurance is improved.

Description

[0001] This case is CN202010986847.7, filed on September 18, 2020, and is a divisional application entitled “Coasting feedback adaptive degradation control method and control system for electric vehicles”. Technical Field

[0002] The present invention relates to the technical field of vehicle energy recovery, and in particular to a coasting feedback adaptive degradation control method and control system for an electric vehicle. Background Art

[0003] At present, most new energy vehicles use the accelerator to release the accelerator for coasting feedback to use the deceleration efficiency to charge the high-voltage battery to improve the vehicle's range or fuel economy, and provide a variety of coasting feedback levels such as strong, medium and weak for users to choose to match their diverse needs. The maximum deceleration of the strong-level coasting feedback can reach more than 0.2g. However, in some special working conditions (such as ice and snow slippery roads, high and low adhesion alternating roads), when the vehicle is coasting, due to the low adhesion of the low-slip road surface and the large coasting feedback torque, it is very easy to cause the wheels to lock and activate the ABS.

[0004] At present, most car companies generally cancel the coasting feedback immediately when the ABS is activated, and then resume the coasting feedback after the ABS is exited. Or they use experienced chassis brake suppliers to make wheel lock correction factors for the feedback torque, and when the wheel is detected to be about to lock, reduce the coasting feedback torque to restore the wheel to normal.

[0005] The feedback is disabled across the board by detecting ABS activation to cancel the coasting feedback, ABS exiting, and then delaying the restoration of the coasting feedback. Although it can solve the feedback locking problem to a certain extent, it is easy to cause sudden changes in deceleration during coasting, causing discomfort to the driver, and the road load is not effectively used for feedback power generation.

[0006] With the help of an experienced chassis brake supplier, the feedback torque is used as a wheel lock correction factor. When the wheel is detected to be about to lock, the sliding feedback torque is reduced to restore the wheel to normal. First, although it can maximize the use of road adhesion feedback, it is difficult to match and depends more on the technical level and cooperation of the chassis brake supplier. Second, because the wheel lock correction factor is calculated in real time based on the wheel speed, it is greatly affected by road fluctuations. High and low adhesion alternating roads can easily cause the feedback torque to be large and small, resulting in a poor driving feel. Summary of the invention

[0007] An object of the first aspect of the present invention is to provide a coasting feedback adaptive degradation control method and system for an electric vehicle, so as to solve the problem in the prior art that the ABS activates and cancels the coasting feedback, resulting in a poor driving feel;

[0008] Another object of the first aspect of the present invention is to solve the problem of wheel locking and frequent ABS activation due to excessive feedback in the prior art.

[0009] Another purpose of the first aspect of the present invention is to solve the problem that the current system is greatly affected by fluctuations in road conditions and has a poor driving feel.

[0010] A second aspect of the present invention aims to provide a coasting feedback adaptive degradation control system for an electric vehicle.

[0011] According to a first aspect of the present invention, the present invention provides a coasting feedback adaptive degradation control method for an electric vehicle, wherein the electric vehicle has at least two different coasting feedback levels, and the coasting feedback adaptive degradation control method for the electric vehicle comprises:

[0012] Collecting status data for indicating the status of the electric vehicle;

[0013] Determining whether the vehicle meets a first condition according to the status data;

[0014] When the vehicle satisfies the first condition, determining whether the vehicle satisfies a second condition;

[0015] When the vehicle satisfies the second condition, controlling the coasting feedback level of the vehicle to be reduced by one level or maintained at a minimum level;

[0016] The first condition is that the vehicle is in a drivable state, the vehicle is in a D / R gear, the reference speed of the vehicle exceeds a predetermined value, the vehicle is in an unbraked state, and the vehicle is in a feedback state;

[0017] The second condition is selected from any one of the following: the estimated road adhesion coefficient is less than a preset value and the time for which the estimated road adhesion coefficient is less than the preset value exceeds a first preset time, the wheel tends to be locked, or the ABS is activated.

[0018] Optionally, it also includes:

[0019] Determine whether a third condition is met, and when the third condition is met, restore the coasting feedback level of the vehicle, wherein the third condition includes any one of the following conditions:

[0020] The driver demand torque is positive; or

[0021] The vehicle is in P / N gear.

[0022] Optionally, after determining whether the third condition is met, the method further includes:

[0023] outputting a feedback output level of the vehicle according to whether the vehicle satisfies the second condition, whether the vehicle satisfies the third condition, and the pre-selected feedback level, wherein the feedback output level is a feedback level actually output by the vehicle;

[0024] Requesting the vehicle to output a corresponding feedback torque according to the feedback output level;

[0025] Wherein, when the vehicle meets the third condition, the feedback output level of the vehicle is the initial feedback level, and the initial feedback level is the pre-selected feedback level;

[0026] When the vehicle does not meet the third condition but meets the second condition, the feedback output level of the vehicle is selected from the already downgraded feedback level, downgraded by one level, and compared with the pre-selected feedback level to obtain the smaller level;

[0027] When the vehicle satisfies neither the third condition nor the second condition, the feedback output level of the vehicle is selected from the feedback output level of the vehicle output, which is the smaller level between the feedback level that has been degraded and the pre-selected feedback level;

[0028] After the feedback output level is degraded, the determination of the second condition and the third condition is repeated.

[0029] Optionally, after the coasting level of the vehicle is reduced by one level, whether the vehicle satisfies the first condition and the second condition is re-determined, and when it is determined that the vehicle satisfies the first condition and the second condition, the coasting feedback level of the vehicle is further reduced by one level;

[0030] The above process is repeated until the sliding feedback level is 0.

[0031] Optionally, the estimated ground adhesion coefficient is less than a preset value means that the estimated ground adhesion coefficient is less than a smaller value of a first set value and a second set value, wherein the first set value x1=(|g1| / g)+s, and the second set value x2=|T| / (F*r*g)+s;

[0032] Among them, g1 is the deceleration corresponding to the current feedback level, g is the gravity deceleration, s is the offset, T is the feedback torque request, F is the vehicle weight, and r is the tire radius.

[0033] Optionally, when the following conditions are met and the time for which the conditions are met exceeds a second preset time, it indicates that the wheel is locked:

[0034] The wheel speed is lower than the reference vehicle speed and the wheel speed change rate is lower than a first threshold; or

[0035] The wheel speed change rate is lower than a second threshold, the first threshold and the second threshold are both negative values, and the first threshold>the second threshold.

[0036] Optionally, the vehicle's ABS system is activated when any of the following conditions are met:

[0037] The ABS system is continuously activated for more than a third set time;

[0038] The ABS system activation time cumulatively exceeds a fourth set time.

[0039] The present invention further provides a coasting feedback adaptive degradation control system for an electric vehicle, wherein the electric vehicle has at least two different coasting feedback levels, and the control system comprises:

[0040] A collection module, collecting status data for indicating the status of the electric vehicle;

[0041] A first judgment module, used for judging whether the vehicle satisfies a first condition according to the state data;

[0042] A second judgment module, configured to judge whether the vehicle satisfies a second condition when the vehicle satisfies the first condition; and

[0043] a control module, configured to control the coasting feedback level of the vehicle to be reduced by one level or maintained at a minimum level when the vehicle satisfies the second condition;

[0044] The first condition is that the vehicle is in a drivable state, the vehicle is in the D / R gear, the reference speed of the vehicle exceeds a predetermined value, the vehicle is in an unbraked state, and the required torque of the vehicle is negative;

[0045] The second condition is selected from any one of the following: the estimated road adhesion coefficient is less than a preset value and the time for which the estimated road adhesion coefficient is less than the preset value exceeds a first preset time, the wheel tends to be locked, or the ABS is activated.

[0046] The control system further includes a feedback level recovery module, the level recovery module is used to determine whether a third condition is met, and when the third condition is met, the coasting feedback level of the vehicle is restored, and the third condition includes any one of the following conditions:

[0047] The driver demand torque is positive; or

[0048] The vehicle is in P / N gear.

[0049] The control system also includes:

[0050] a feedback level output module, configured to output a feedback output level of the vehicle according to whether the vehicle satisfies the second condition, whether the vehicle satisfies the third condition, and the pre-selected feedback level, wherein the feedback output level is a feedback level actually output by the vehicle; and

[0051] a torque request module, configured to request the vehicle to output a corresponding feedback torque according to the feedback output level;

[0052] Wherein, when the vehicle meets the third condition, the feedback output level of the vehicle is the initial feedback level, and the initial feedback level is the pre-selected feedback level;

[0053] When the vehicle does not meet the third condition but meets the second condition, the feedback output level of the vehicle is selected from the already downgraded feedback level, downgraded by one level, and compared with the pre-selected feedback level to obtain the smaller level;

[0054] When the vehicle satisfies neither the third condition nor the second condition, the feedback output level of the vehicle is selected from the feedback output level of the vehicle output, which is the smaller level between the feedback level that has been degraded and the pre-selected feedback level;

[0055] After the feedback output level is degraded, the determination of the second condition and the third condition is repeated.

[0056] After determining that the vehicle meets the first condition and the second condition, the present invention performs a downgrade process on the coasting feedback of the vehicle. In the second condition, when the ABS of the vehicle is activated, the coasting feedback is not directly exited, but only downgraded, so that the sudden change in the deceleration feeling of the vehicle during coasting will not cause discomfort to the driver, and the road load is effectively used to feedback power generation, which is better than the direct cancellation of feedback in the prior art. In addition, in the present application, when the ABS is activated, the feedback torque is gradually reduced and a waiting time is left, which is smoother than the sudden loss of the deceleration feeling caused by directly canceling the feedback torque, and the driving feel is smoother.

[0057] When the ABS is activated or detects that the wheel is close to the locking limit, the present invention first reduces the feedback torque by one feedback level to determine whether the wheel locking has been improved. If effective, the current feedback level will be maintained to prevent the wheel from locking again and triggering the ABS after the feedback is restored after the ABS is exited. Compared with the prior art, the feedback is directly cancelled and the ABS will not be frequently activated.

[0058] The present invention actively identifies low-adhesion roads through low-adhesion calculation, wheel lock prediction, ABS activation prediction, etc. to downgrade feedback and maintain it. Under acceleration and other working conditions, the initial feedback level will be reasonably restored without manual operation by the driver. Compared with the existing technology that directly cancels feedback, it can reasonably use road adhesion to feedback power generation and improve pure electric endurance.

[0059] In a single coasting feedback condition, the present invention will trigger feedback degradation through the cumulative ABS activation time exceeding the limit or the ABS continuous activation exceeding the limit, and is compatible with typical conditions such as continuous low-adhesion road surfaces (slippery ice and snow road surfaces) and intermittent low-adhesion road surfaces (ice and snow chessboard road surfaces).

[0060] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0062] Figure 1 is a schematic flow chart of a coasting feedback adaptive degradation control method for an electric vehicle according to an embodiment of the present invention;

[0063] Figure 2 is a specific working flow chart of a coasting feedback adaptive degradation control method for an electric vehicle according to an embodiment of the present invention;

[0064] Figure 3 is a schematic flow chart of a coasting feedback adaptive degradation control method for an electric vehicle according to another embodiment of the present invention;

[0065] Figure 4 is a specific working flow chart of a coasting feedback adaptive degradation control method for an electric vehicle according to another embodiment of the present invention;

[0066] Figure 5 is a schematic block diagram of a coasting feedback adaptive degradation control system for an electric vehicle according to an embodiment of the present invention;

[0067] Figure 6 is a schematic block diagram of a collection module connected to a data monitoring and calculation module of a coasting feedback adaptive degradation control system of an electric vehicle according to an embodiment of the present invention;

[0068] Figure 7 is a schematic block diagram of a coasting feedback adaptive degradation control system for an electric vehicle according to another embodiment of the present invention. DETAILED DESCRIPTION

[0069] Figure 1The present invention is a schematic flow chart of a coasting feedback adaptive degradation control method for an electric vehicle according to an embodiment of the present invention. A coasting feedback adaptive degradation control method for an electric vehicle. Specifically, the electric vehicle of this embodiment has at least two different coasting feedback levels. The control method may specifically include:

[0070] S10 collects status data for indicating the status of the electric vehicle;

[0071] S20 determines whether the vehicle meets the first condition according to the status data;

[0072] S30, when the vehicle satisfies the first condition, determining whether the vehicle satisfies the second condition;

[0073] S40: when the vehicle satisfies the second condition, controlling the coasting feedback level of the vehicle to be reduced by one level or maintained at the lowest level;

[0074] Among them, the first condition is that the vehicle is in a drivable state, the vehicle is in D / R gear, the reference speed of the vehicle exceeds a predetermined value, the vehicle is in an unbraked state, and the required torque of the vehicle is negative (release the accelerator); specifically, the above four conditions need to be met at the same time to meet the first condition. Specifically, the vehicle is in a drivable state when the vehicle is powered on but not started. The reference speed in this embodiment is the longitudinal speed at the center of mass of the vehicle, which ranges from 0 to 255 km / h.

[0075] The second condition is selected from any one of the following: the estimated ground adhesion coefficient is less than a preset value and the time for which the estimated ground adhesion coefficient is less than the preset value exceeds a first preset time, the wheel tends to be locked, or the ABS is activated. Specifically, only one of the three conditions needs to be met to meet the second condition.

[0076] In actual process, the coasting feedback levels include strong level, medium level, weak level and level 0. When the vehicle itself is at the lowest level, i.e., level 0, and the vehicle meets the second condition, it cannot and does not need to be downgraded.

[0077] In this embodiment, after determining that the vehicle meets the first condition and the second condition, the vehicle performs a coasting feedback downgrade process. In the second condition, when the ABS of the vehicle is activated, the coasting feedback is not directly exited, but only downgraded, so that the sudden change in the deceleration feeling of the vehicle during coasting will not cause discomfort to the driver, and the road load is effectively used to feedback power generation, which is better than directly canceling the feedback. In addition, in this application, when the ABS is activated, the feedback torque is gradually reduced and a waiting time is left. Compared with the sudden loss of the deceleration feeling caused by directly canceling the feedback torque, the driving feel is smoother.

[0078] When the ABS is activated or detects that the wheel is close to the locking limit, the embodiment first reduces the feedback torque by one feedback level to determine whether the wheel locking has been improved. If effective, the current feedback level will be maintained to prevent the wheel from locking again and triggering the ABS after the feedback is restored after the ABS is exited. Compared with the prior art, the feedback is directly cancelled and the ABS is not frequently activated.

[0079] Figure 2 It is a specific working flow chart of the coasting feedback adaptive degradation control method for an electric vehicle according to an embodiment of the present invention; specifically, the estimated ground adhesion coefficient in the second condition is less than the preset value, the estimated ground adhesion coefficient is less than the smaller value of the first set value and the second set value, wherein the first set value x1=(|g1| / g)+s, the second set value x2=|T| / (F*r*g)+s; wherein g1 is the deceleration corresponding to the current feedback level, g is the gravity deceleration, s is the offset, T is the feedback torque request, F is the vehicle weight, and r is the tire radius.

[0080] The reference deceleration speeds for strong, medium and weak feedback levels are 0.15g / 0.1g / 0.05g. The specific deceleration speeds corresponding to the feedback levels depend on the project requirements.

[0081] More specifically, when any one of the following fourth conditions is met and the time for which the fourth condition is met exceeds the second preset time, it indicates that the wheel is locked, and the fourth condition includes:

[0082] The wheel speed is lower than the reference vehicle speed and the wheel speed change rate is lower than a first threshold; or

[0083] The wheel speed change rate is lower than the second threshold, the first threshold and the second threshold are both negative values, and the first threshold is greater than the second threshold.

[0084] The reference speed in this embodiment is the longitudinal speed at the center of mass of the vehicle, which ranges from 0 to 255 km / h. The first threshold is -1000 km / h / s to -200 km / h / s, which can be adjusted according to the actual vehicle conditions. The second threshold is -1000 km / h / s to -400 km / h / s.

[0085] More specifically, when any one of the following fifth conditions is met, it indicates that the ABS system of the vehicle is activated, wherein the fifth condition includes:

[0086] The ABS system is continuously activated for a period exceeding a third set time; or

[0087] The cumulative activation time of the ABS system exceeds the fourth set time.

[0088] The third setting time is 0.1s to 10s, which depends on the actual vehicle. The fourth setting time is 0.1s to 10s, which depends on the actual vehicle.

[0089] This embodiment makes reasonable use of road surface feedback to reduce the driver's frequent switching of feedback levels. Specifically, the present invention actively identifies low-adhesion roads through low-adhesion calculation, wheel lock prediction, ABS activation, etc. to downgrade feedback and maintain it. Acceleration and other working conditions will reasonably restore the initial feedback level without the need for manual operation by the driver. Compared with the prior art that directly cancels feedback, it can reasonably use road adhesion to feedback power generation and improve pure electric endurance.

[0090] The fifth condition of this embodiment is that in a single coasting feedback condition, feedback degradation will be triggered by the cumulative ABS activation time exceeding the limit or the ABS continuous activation exceeding the limit, which is compatible with typical conditions such as continuous low-adhesion road surfaces (slippery ice and snow road surfaces) and intermittent low-adhesion road surfaces (ice and snow chessboard road surfaces).

[0091] Figure 3 is a schematic flow chart of a coasting feedback adaptive degradation control method for an electric vehicle according to another embodiment of the present invention; Figure 4 It is a specific working flow chart of a coasting feedback adaptive degradation control method for an electric vehicle according to another embodiment of the present invention.

[0092] More specifically, the coasting feedback adaptive degradation control method for an electric vehicle may also include:

[0093] S50 determines whether a third condition is satisfied. When any of the following third conditions is satisfied, the coasting feedback level of the vehicle is restored. The third condition includes:

[0094] The driver demand torque is positive (accelerator pedal driven); or

[0095] The vehicle is in P / N position.

[0096] More specifically, S60 outputs the feedback output level of the vehicle according to whether the vehicle satisfies the second condition, whether the vehicle satisfies the third condition, and the pre-selected feedback level;

[0097] S70 requests the vehicle to output a corresponding feedback torque according to the feedback output level;

[0098] When the vehicle meets the third condition, the feedback output level of the vehicle is the initial feedback level, and the initial feedback level is the pre-selected feedback level. This state is defined as state 1.

[0099] When the vehicle does not meet the third condition but meets the second condition, the feedback output level of the vehicle is selected from the already downgraded feedback level and then downgraded by one level and compared with the pre-selected feedback level to obtain the smaller level; this state is defined as state 3. This process can respond to the driver's operation of lowering the feedback level in a timely manner and avoid negative values ​​in the feedback level after the downgrade.

[0100] When the vehicle satisfies neither the third condition nor the second condition, the feedback output level of the vehicle is selected from the feedback output level of the vehicle output, which maintains the feedback level that has been degraded and the feedback level that is pre-selected, and takes the smaller level; this state is defined as state 2. This process can respond to the driver's operation of lowering the feedback level in a timely manner.

[0101] After the feedback output level is degraded, the second and third conditions are repeated.

[0102] When the feedback level of the vehicle output is downgraded (i.e., state 3 is established), if the vehicle does not meet the third condition but meets the second condition, the feedback output level of the vehicle output will be downgraded by one level based on the already downgraded feedback level and compared with the pre-selected feedback level to obtain the smaller level output.

[0103] When the feedback level of the vehicle output is degraded (ie, state 3 is established), if the vehicle does not meet the third condition and the second condition, the feedback output level of the vehicle output will maintain the degraded feedback level and compare it with the pre-selected feedback level to obtain the smaller level output.

[0104] The transition conditions of the state machine between state 1 and state 3 are:

[0105] Condition for state 1 to jump to state 3: the second condition is met.

[0106] Condition for state 2 to jump to state 3: the second condition is met.

[0107] The condition for state 1 to jump to state 2 is: the second condition is not satisfied and the third condition is satisfied.

[0108] Conditions for state 3 to jump to state 2: the second condition is not satisfied and the third condition is not satisfied.

[0109] The condition for state 3 to jump to state 1 is: the third condition is met;

[0110] Condition for state 2 to jump to state 1: the third condition is met.

[0111] In this embodiment, during the vehicle coasting feedback process, the feedback level is downgraded in sequence through state detection such as whether the road adhesion supports the current feedback, wheel lock prediction, ABS activation (second condition), etc., thereby reducing the feedback torque. When the driver steps on the accelerator to drive (third condition), the feedback level can be quickly restored to achieve the purpose of maximizing the utilization of road adhesion feedback and reducing frequent ABS activation in the entire driving condition.

[0112] In addition, the coasting feedback adaptive degradation control method of the electric vehicle of the present application can also re-judge whether the vehicle meets the first condition and the second condition after the coasting level of the vehicle is reduced by one level, and when it is determined that the vehicle meets the first condition and the second condition, the coasting feedback level of the vehicle is further reduced by one level; repeat the above process until the coasting feedback level is level 0. This process shows that in the process of coasting feedback of the present method, as long as the coasting feedback is not reduced to level 0, the detection and judgment process continues, and the level of coasting feedback is adjusted in real time according to the specific working conditions and status of the vehicle, so as to ensure the smoothness of driving and improve the pure electric endurance.

[0113] Figure 5 It is a schematic block diagram of a coasting feedback adaptive degradation control system for an electric vehicle according to an embodiment of the present invention; as a specific embodiment of the present invention, this embodiment also provides a coasting feedback adaptive degradation control system 100 for an electric vehicle, and the electric vehicle has at least two different coasting feedback levels. The system 100 may include a collection module 10, a first judgment module 20, a second judgment module 30 and a control module 40. The collection module 10 is used to collect the state data of the vehicle. The first judgment module 20 is used to judge whether the vehicle meets the first condition according to the state data. The second judgment module 30 is used to judge whether the vehicle meets the second condition when the vehicle meets the first condition. The control module 40 is used to control the coasting feedback level of the vehicle to be reduced by one level or maintained at the lowest level when the vehicle meets the second condition. Among them, the first condition is that the vehicle is in a drivable state, the vehicle is in D / R gear, the reference speed of the vehicle exceeds a predetermined value, the vehicle is in an unbraked state, and the vehicle is in a feedback state. Specifically, the above four conditions need to be met at the same time to meet the first condition. Specifically, the vehicle is in a drivable state when the vehicle is powered on and started, but the vehicle is not started. The reference vehicle speed in this embodiment is the longitudinal vehicle speed at the center of mass of the vehicle, which ranges from approximately 0 to 255 km / h.

[0114] The second condition is selected from one of the following: the estimated ground adhesion coefficient is less than a preset value and the time for which the estimated ground adhesion coefficient is less than the preset value exceeds a first preset time, the wheel tends to be locked, or the ABS is activated. Specifically, only one of the three conditions needs to be met to meet the second condition.

[0115] The preset value is a vehicle speed between 3 and 10 km / h, which can be adjusted according to the actual vehicle conditions. The first preset time is 0.05s to 10s, which depends on the actual vehicle.

[0116] In actual process, the coasting feedback levels include strong level, medium level, weak level and level 0. When the vehicle itself is at the lowest level, i.e., level 0, and the vehicle meets the second condition, it cannot and does not need to be downgraded.

[0117] Figure 6 The present invention is a schematic block diagram of an acquisition module of a coasting feedback adaptive degradation control system of an electric vehicle according to an embodiment of the present invention connected to a data monitoring and calculation module; specifically, the acquisition module can acquire data detected or calculated by a vehicle reference speed calculation unit (ECU1), a road adhesion coefficient calculation unit (ECU2), an ABS (anti-lock braking system) control unit (ECU3), a gear selection module (MCU1), an upper and lower power management module (MCU2), a torque demand calculation module (MCU3), a wheel speed sensor (Sensor1), a brake pedal sensor (Sensor2), a human-computer interaction unit (HMI), a timer (Timer1) and a torque execution unit (Actuator1).

[0118] Specifically, the vehicle reference speed calculation unit estimates the speed of the vehicle center of mass based on information such as wheel speed and longitudinal acceleration to represent the actual longitudinal speed of the vehicle. The road adhesion coefficient calculation unit estimates the road adhesion coefficient based on vehicle slippage, yaw instability, etc. to represent the driving force or braking force coefficient that can be effectively used on the current road surface.

[0119] The ABS (anti-lock braking system) control unit is used to detect wheel locking caused by low ground adhesion or over-braking, actively clamp and release the braking force to improve braking performance, and provide an ABS status signal to indicate whether the ABS is activated.

[0120] The gear selection module allows the driver to switch the direction of vehicle movement by performing gear shifting operations, and provides a PRND gear signal to represent the driver's intention to move the vehicle forward, backward, coast, park, etc.

[0121] Power management module: manages high and low voltage power supply, key electrical components and power system operation, anti-theft system authentication, etc., and provides vehicle drivable status signal to indicate that the system can support vehicle driving normally.

[0122] The torque demand calculation module calculates the power system drive / feedback torque request based on various factors such as throttle opening, vehicle speed, driving mode, power system capability, actual feedback level, etc., and provides the driver's required torque and drive / feedback torque request signals to the motor and other torque execution units to output torque.

[0123] The four wheel speed sensors monitor the wheel speeds of the left front, right front, left rear and right rear wheels in real time and provide other modules.

[0124] The brake pedal sensor monitors the driver's action of pressing the brake pedal in real time and provides a brake pedal pressing status signal to indicate whether the driver has pressed the brake pedal.

[0125] The human-machine interaction unit allows the driver to adjust the power system feedback intensity by selecting strong, medium or weak feedback levels, provides the driver with a selected feedback level signal RgnLvlSelected (i.e., the pre-selected feedback level), and receives the actual feedback level RgnLvlActIndcn to prompt the user.

[0126] The timer is used to measure the duration or the accumulated trigger time within a period of time when certain conditions are triggered. The timer can also be reset when certain conditions are met.

[0127] The torque execution unit is a device that outputs torque after receiving a drive / feedback torque request, such as a motor.

[0128] After the present invention determines that the vehicle meets the first condition and the second condition, the vehicle performs a coasting feedback downgrade process. In the second condition, when the ABS of the vehicle is activated, the coasting feedback is not directly exited, but only downgraded, which is better than the direct cancellation of feedback in the prior art. In addition, in the present application, when the ABS is activated, the feedback torque is gradually reduced and a waiting time is left. Compared with the sudden loss of the deceleration feeling caused by the direct cancellation of the feedback torque, the driving feel is smoother.

[0129] When the ABS is activated or detects that the wheel is close to the locking limit, the present invention first reduces the torque of one feedback level to determine whether the wheel locking has been improved. If effective, the current feedback level will be maintained to prevent the wheel from locking again and triggering the ABS after the feedback is restored after the ABS is exited. Compared with the prior art, the feedback is directly cancelled and the ABS will not be frequently activated.

[0130] Figure 7 It is a specific working flow chart of a coasting feedback adaptive degradation control system for an electric vehicle according to another embodiment of the present invention.

[0131] Specifically, the coasting feedback adaptive degradation control system of the electric vehicle of this embodiment may further include a feedback level recovery module 50, which is used to determine whether any of the following third conditions is met, and if so, restore the coasting feedback level of the vehicle, the third condition comprising:

[0132] The driver demand torque is positive; or

[0133] The vehicle is in P / N position.

[0134] The third condition is mainly based on the gear of the vehicle selected by the gear selection module and the driver's required torque calculated by the torque demand calculation module.

[0135] The third condition is mainly to be able to maintain the level of the glide feedback or return it to the initial glide feedback level.

[0136] Specifically, the coasting feedback adaptive degradation control system of the electric vehicle of this embodiment may also include a feedback level output module 60 and a torque request module 70. The feedback level output module 60 is used to output the feedback output level of the vehicle according to whether the vehicle meets the second condition, whether the third condition is met, and the pre-selected feedback level. The torque request module 70 is used to request the vehicle to output a corresponding feedback torque according to the feedback output level. Among them, when the vehicle meets the third condition, the feedback output level of the vehicle is the initial feedback level, and the initial feedback level is the pre-selected feedback level. Define this state as state 1.

[0137] When the vehicle satisfies neither the third condition nor the second condition, the feedback output level of the vehicle is selected from the feedback output level of the vehicle output, which is the smaller level of the feedback level that has been degraded and the pre-selected feedback level. This process can respond to the driver's operation of lowering the feedback level in a timely manner. This state is defined as state 2.

[0138] When the vehicle does not meet the third condition but meets the second condition, the feedback output level of the vehicle is selected from the already downgraded feedback level and then downgraded by one level and compared with the pre-selected feedback level to obtain the smaller level. This process can respond to the driver's operation of downgrading the feedback level in a timely manner and avoid negative feedback levels after downgrading. This state is defined as state 3.

[0139] After the feedback output level is degraded, the determination of the second condition and the third condition is repeated.

[0140] Specifically, when the feedback level of the vehicle output is downgraded (i.e., state 3 is established), if the vehicle does not meet the third condition but meets the second condition, the feedback level of the vehicle output will be downgraded by one level based on the already downgraded feedback level and compared with the pre-selected feedback level to obtain a smaller level output.

[0141] When the feedback level of the vehicle output is degraded (ie, state 3 is established), if the vehicle does not meet the third condition and the second condition, the feedback level of the vehicle output will maintain the degraded feedback level and compare it with the pre-selected feedback level to obtain the smaller level output.

[0142] The transition conditions of the state machine between state 1 and state 3 are:

[0143] Condition for state 1 to jump to state 3: the second condition is met.

[0144] Condition for state 2 to jump to state 3: the second condition is met.

[0145] The condition for state 1 to jump to state 2 is: the second condition is not satisfied and the third condition is satisfied.

[0146] Conditions for state 3 to jump to state 2: the second condition is not satisfied and the third condition is not satisfied.

[0147] Condition for state 3 to jump to state 1: the third condition is met.

[0148] Condition for state 2 to jump to state 1: the third condition is met.

[0149] In this embodiment, during the vehicle coasting feedback process, the feedback level is downgraded in sequence through state detection such as whether the road adhesion supports the current feedback, wheel lock prediction, ABS activation (second condition), etc., thereby reducing the feedback torque. When the driver steps on the accelerator to drive (third condition), the feedback level can be quickly restored to achieve the purpose of maximizing the utilization of road adhesion feedback and reducing frequent ABS activation in the entire driving condition.

[0150] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A coasting feedback adaptive degradation control method for an electric vehicle, wherein the electric vehicle has at least two different coasting feedback levels, characterized in that: The coasting feedback adaptive degradation control method of the electric vehicle comprises: Collecting status data for indicating the status of the electric vehicle; Determining whether the vehicle meets a first condition according to the status data; When the vehicle satisfies the first condition, determining whether the vehicle satisfies a second condition; When the vehicle satisfies the second condition, controlling the coasting feedback level of the vehicle to be reduced by one level or maintained at a minimum level; The first condition is that the vehicle is in a drivable state, the vehicle is in a D / R gear, the reference speed of the vehicle exceeds a predetermined value, the vehicle is in an unbraked state, and the vehicle is in a feedback state; The second condition is selected from any one of the following: the estimated road adhesion coefficient is less than a preset value and the time for which the estimated road adhesion coefficient is less than the preset value exceeds a first preset time, the wheel tends to be locked, or the ABS is activated; Also includes: Determine whether a third condition is met, and when the third condition is met, restore the coasting feedback level of the vehicle, wherein the third condition includes any one of the following conditions: The driver demand torque is positive; or The vehicle is in P / N gear; When the coasting level of the vehicle is reduced by one level, re-determining whether the vehicle satisfies the first condition and the second condition; when it is determined that the vehicle satisfies the first condition and the second condition, further reducing the coasting feedback level of the vehicle by one level; Repeat the above process until the sliding feedback level is 0; When the following conditions are met and the time for which the conditions are met exceeds a second preset time, it indicates that the wheel is locked: The wheel speed is lower than the reference vehicle speed and the wheel speed change rate is lower than a first threshold; or The wheel speed change rate is lower than a second threshold, the first threshold and the second threshold are both negative values, and the first threshold>the second threshold.

2. The coasting feedback adaptive degradation control method of an electric vehicle according to claim 1, characterized in that: After determining whether the third condition is met, the method further includes: outputting a feedback output level of the vehicle according to whether the vehicle satisfies the second condition, whether the vehicle satisfies the third condition, and a pre-selected feedback level, wherein the feedback output level is a feedback level actually output by the vehicle; Requesting the vehicle to output a corresponding feedback torque according to the feedback output level; Wherein, when the vehicle meets the third condition, the feedback output level of the vehicle is the initial feedback level, and the initial feedback level is the pre-selected feedback level; When the vehicle does not meet the third condition but meets the second condition, the feedback output level of the vehicle is selected from the already downgraded feedback level, downgraded by one level, and compared with the pre-selected feedback level to obtain the smaller level; When the vehicle satisfies neither the third condition nor the second condition, the feedback output level of the vehicle is selected from the feedback output level of the vehicle output, which is the smaller level between the feedback level that has been degraded and the pre-selected feedback level; After the feedback output level is degraded, the determination of the second condition and the third condition is repeated.

3. The coasting feedback adaptive degradation control method of an electric vehicle according to claim 1, characterized in that: The estimated ground adhesion coefficient is less than the preset value means that the estimated ground adhesion coefficient is less than the smaller value of a first set value and a second set value, wherein the first set value x1=(|g1| / g)+s, and the second set value x2=|T| / (F*r*g)+s; Among them, g1 is the deceleration corresponding to the current feedback level, g is the gravity deceleration, s is the offset, T is the feedback torque request, F is the vehicle weight, and r is the tire radius.

4. The coasting feedback adaptive degradation control method of an electric vehicle according to claim 1, characterized in that: The vehicle's ABS system is activated when any of the following conditions are met: The ABS system is continuously activated for more than a third set time; The ABS system activation time cumulatively exceeds a fourth set time.

5. A coasting feedback adaptive degradation control system for an electric vehicle, the electric vehicle having at least two different coasting feedback levels, characterized in that: include: A collection module, collecting status data for indicating the status of the electric vehicle; A first judgment module, used for judging whether the vehicle satisfies a first condition according to the state data; A second judgment module, used for judging whether the vehicle satisfies a second condition when the vehicle satisfies the first condition; and a control module, configured to control the coasting feedback level of the vehicle to be reduced by one level or maintained at a minimum level when the vehicle satisfies the second condition; The first condition is that the vehicle is in a drivable state, the vehicle is in the D / R gear, the reference speed of the vehicle exceeds a predetermined value, the vehicle is in an unbraked state, and the required torque of the vehicle is negative; The second condition is selected from any one of the following: the estimated road adhesion coefficient is less than a preset value and the time for which the estimated road adhesion coefficient is less than the preset value exceeds a first preset time, the wheel tends to be locked, or the ABS is activated; The system further includes a feedback level recovery module, wherein the level recovery module is used to determine whether a third condition is met, and when the third condition is met, the coasting feedback level of the vehicle is restored, wherein the third condition includes any one of the following conditions: The driver demand torque is positive; or The vehicle is in P / N gear; When the coasting level of the vehicle is reduced by one level, re-determining whether the vehicle satisfies the first condition and the second condition; when it is determined that the vehicle satisfies the first condition and the second condition, further reducing the coasting feedback level of the vehicle by one level; Repeat the above process until the sliding feedback level is 0; When the following conditions are met and the time for which the conditions are met exceeds a second preset time, it indicates that the wheel is locked: The wheel speed is lower than the reference vehicle speed and the wheel speed change rate is lower than a first threshold; or The wheel speed change rate is lower than a second threshold, the first threshold and the second threshold are both negative values, and the first threshold>the second threshold.

6. The coasting feedback adaptive degradation control system of an electric vehicle according to claim 5, characterized in that: Also includes: a feedback level output module, configured to output a feedback output level of the vehicle according to whether the vehicle satisfies the second condition, whether the vehicle satisfies the third condition, and a pre-selected feedback level, wherein the feedback output level is a feedback level actually output by the vehicle; and a torque request module, configured to request the vehicle to output a corresponding feedback torque according to the feedback output level; Wherein, when the vehicle meets the third condition, the feedback output level of the vehicle is the initial feedback level, and the initial feedback level is the pre-selected feedback level; When the vehicle does not meet the third condition but meets the second condition, the feedback output level of the vehicle is selected from the feedback level that has been downgraded, and then downgraded by one level and compared with the pre-selected feedback level to obtain the smaller level; When the vehicle satisfies neither the third condition nor the second condition, the feedback output level of the vehicle is selected from the feedback output level of the vehicle output, which is the smaller level between the feedback level that has been degraded and the pre-selected feedback level; After the feedback output level is degraded, the determination of the second condition and the third condition is repeated.

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