Control method of electric vehicle, controller and electric vehicle

Abstract

The invention provides a control method of an electric vehicle, a controller and the electric vehicle. After the electric vehicle starts to bend and before a steering wheel starts to rotate, the ratio of the torque output by a driving system to a front axle and a rear axle is controlled to be smaller than the ratio of the torque output by the driving system to the front axle and the rear axle before the electric vehicle starts to bend; therefore, by means of the mode that the ratio of the torque output by the front axle to the torque output by the rear axle is visibly reduced, before the lateral force of the front wheels of the electric vehicle actually begins to be increased, preparation is made for increasing of the lateral force in advance, and the effect of improving the driving stability of the electric vehicle in the bending process is achieved.

Description

A control method, controller, and electric vehicle for an electric vehicle Technical Field

[0001] This application relates to the field of new energy vehicle technology, and in particular to a control method, controller, and electric vehicle for electric vehicles. Background Technology

[0002] When driving on curved roads, vehicles rely primarily on driver input to maintain stability. However, at high speeds, drivers struggle to react quickly enough to adjust their steering, and their operational capabilities are limited to steering, accelerator pedal control, and brake pedal control. In scenarios involving consecutive curves or sharp bends, not only is timely and appropriate maneuvering difficult, but even when achievable, drivers often struggle to maintain stable control through steering and accelerator pedal input, leading to issues such as understeer.

[0003] Therefore, improving vehicle driving stability is an urgent problem to be solved. Summary of the Invention

[0004] This application provides a control method, controller, and electric vehicle for an electric vehicle. By controlling the drive system to adjust the torque distribution to the front and rear axles of the electric vehicle during cornering, the driving stability of the electric vehicle during cornering is improved.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] Firstly, a control method for an electric vehicle is provided. During the electric vehicle's journey before entering a curve, the method controls the sum of the torques output by the drive system to the front and rear axles of the electric vehicle to vary with the accelerator pedal opening. During the electric vehicle's entry into the curve, before the steering wheel begins to turn, the method controls the ratio of the torques output by the drive system to the front and rear axles to be less than the ratio of the torques output by the drive system to the front and rear axles during the journey before entering the curve, and controls the sum of the torques output by the drive system to vary with the accelerator pedal opening.

[0007] Specifically, the curvature of the road traveled by the electric vehicle before entering the curve is less than the curvature of the road traveled by the electric vehicle during the curve entry process, and the curvature of the road traveled by the electric vehicle during the curve entry process increases from small to large.

[0008] The ratio of the torque output by the drive system to the front axle and the rear axle can specifically refer to the ratio of the driving torque output by the drive motor on the front axle to the driving torque output by the drive motor on the rear axle.

[0009] When an electric vehicle enters a curve, the curvature of the road it traverses can be greater than a preset curvature, and this curvature gradually increases as the vehicle progresses. During curve entry, the front wheels not only drive the vehicle but also steer it. The grip generated by the front wheels must simultaneously provide the longitudinal force required for forward movement and the lateral force required for steering. Therefore, the greater the actual longitudinal force on the front wheels, the smaller the allowable lateral force; conversely, the smaller the actual longitudinal force, the greater the allowable lateral force. A greater allowable lateral force means that the actual lateral force generated by the front wheels is less likely to exceed the lateral force limit during steering, making it less likely for the electric vehicle to understeer due to skidding.

[0010] To address this, this embodiment controls the ratio of torque output from the front and rear axles of the drive system during cornering to be less than the ratio during the initial cornering phase. This allows for a heavier drive load on the rear wheels, reducing the burden on the front wheels. With this reduced load, the longitudinal force on the front wheels decreases, allowing for a corresponding increase in the lateral force, which in turn facilitates more effective steering. Simultaneously, the increased drive torque on the rear wheels increases the yaw moment, further aiding in more aggressive cornering. Therefore, this embodiment, by using a smaller front-to-rear axle torque ratio, enhances the cornering aggression of the electric vehicle while enabling the front wheels to more effectively perform steering during cornering, thus preventing understeer and ensuring the vehicle's stability.

[0011] Meanwhile, in this embodiment, before the electric vehicle's steering wheel starts turning and the electric vehicle actually enters a turning state, the torque ratio between the front axle and the rear axle is reduced in advance through forward control. This allows the electric vehicle to prepare for the increase of lateral force before the front wheels actually begin to increase lateral force, thereby further improving the smoothness and safety of the electric vehicle during the cornering process.

[0012] In one implementation of the first aspect, the control method further includes: during the exit of the curve by the electric vehicle, before the steering wheel of the electric vehicle begins to return to center, increasing the ratio of the torque output by the drive system to the front axle and the rear axle, and controlling the sum of the torque output by the drive system to change with the accelerator pedal opening. Specifically, during the exit of the curve by the electric vehicle, the curvature of the road traveled by the electric vehicle decreases from large to small.

[0013] Steering wheel return to center is a turning action relative to the way the steering wheel is turned during the electric vehicle's cornering process. For example, if the steering wheel is turned to the left during the electric vehicle's cornering process, then in this embodiment, steering wheel return to center refers to the action of turning the steering wheel to the right, and "before the electric vehicle's steering wheel begins to return to center" means before the steering wheel begins to turn to the right; if the steering wheel is turned to the right during the electric vehicle's cornering process, then in this embodiment, steering wheel return to center refers to the action of turning the steering wheel to the left, and "before the electric vehicle's steering wheel begins to return to center" means before the steering wheel begins to turn to the left.

[0014] As the electric vehicle begins to exit a curve, the curvature of the road it travels on decreases, indicating a potential for fishtailing. In this embodiment, the drive controller increases the torque ratio between the front and rear axles under these conditions. This reduces the drive load on the rear axle before the steering wheel returns to center and the fishtailing issue actually occurs, allowing the rear wheels to convert more of their grip into lateral force. This prevents the actual lateral force on the rear wheels from exceeding their allowable range during corner exit, thereby reducing the probability of fishtailing.

[0015] In one implementation of the first aspect, the control method further includes: after the electric vehicle exits the curve, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to be greater than the ratio of the torque output by the drive system to the front axle and the rear axle during the exit of the curve.

[0016] After exiting a corner, the electric vehicle regains the driving stability it had before entering the corner. At this point, the ratio of torque output from the drive system to the front and rear axles is greater than the ratio during corner exit, causing the electric vehicle to be more front-wheel drive biased. This front-wheel drive bias creates a tendency for the front wheels to straighten during straight-line acceleration, thus ensuring stability on straightaways.

[0017] In one implementation of the first aspect, the control method further includes: during the process of the electric vehicle entering a curve, during the rotation of the steering wheel of the electric vehicle, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to decrease as the steering wheel angle increases, and controlling the ratio of the torque output by the drive system to the front axle and the rear axle to remain unchanged after the steering wheel of the electric vehicle stops rotating.

[0018] Once the steering wheel of an electric vehicle begins to turn, the steering of the front wheels is controlled by the driver's steering intention. The stronger the driver's steering awareness, the larger the steering wheel angle, and the heavier the steering task borne by the front wheels. Therefore, in this situation, the ratio of torque output from the drive system to the front axle and rear axle can be controlled to increase as the steering wheel angle increases during steering wheel rotation and remain constant when the steering wheel stops turning. This synchronizes the torque distribution with the driver's steering operation, ensuring that the amount of torque distribution providing steering assistance is proportional to the driver's steering intention, thereby enhancing the driver's handling experience.

[0019] In one implementation of the first aspect, the control method further includes: during the process of the electric vehicle entering a curve, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to decrease as the road curvature indicated by the road curvature signal increases.

[0020] When a driver is driving on a road, they first observe the curvature of the road the electric vehicle is traveling on, and then turn the steering wheel according to the observed road curvature to transmit their steering intention to the electric vehicle. After receiving the steering wheel angle input by the driver, the electric vehicle then performs steering control based on the size of the steering wheel angle. Therefore, it can be seen that the electric vehicle receives the driver's steering intention later than the change in road curvature. To address this, this embodiment adaptively adjusts the torque ratio output from the front and rear axles based on the road curvature the electric vehicle is traveling on. This allows the adjustment of the front and rear axle torque ratio and the steering control action of the electric vehicle to be synchronized when the driver observes a change in road curvature, thereby improving the timeliness of electric vehicle control and enabling the electric vehicle to corner more smoothly.

[0021] In one implementation of the first aspect, the control method further includes: during the process of the electric vehicle entering a curve, when the curvature of the road traversed by the electric vehicle increases to a first curvature, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to be a first ratio. During the process of the electric vehicle exiting a curve, when the curvature of the road traversed by the electric vehicle decreases to the first curvature, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to be a second ratio; the first ratio is less than the second ratio.

[0022] Electric vehicles exhibit different body postures during cornering and exiting. Due to inertia, they tend to shift outwards during cornering and inwards during cornering. This embodiment addresses this by controlling the drive system to output different torque ratios to the front and rear axles based on the different postures of the electric vehicle during cornering and exiting. This means that controlling the torque ratio between the front and rear axles no longer simply follows the curvature but also considers the dynamic direction of the electric vehicle under that curvature, thus providing a more precise torque distribution scheme and further improving the driving stability of the electric vehicle.

[0023] In one implementation of the first aspect, the control method further includes: during the electric vehicle's entry into a curve, the faster the curvature of the road the electric vehicle travels increases, the faster the ratio of the torque output by the drive system to the front axle and the rear axle decreases. During the electric vehicle's exit from a curve, the faster the curvature of the road the electric vehicle travels decreases, the faster the ratio of the torque output by the drive system to the front axle and the rear axle increases.

[0024] The rapid increase in road curvature indicates that the electric vehicle is traveling on a rapidly narrowing curve, causing a drastic dynamic change in the driving environment within a short period. To cope with this rapid change, the electric vehicle needs more effective steering responses. Therefore, this implementation controls the rate at which the ratio of torque output from the front and rear axles of the drive system decreases, increasing with the rate of increase in road curvature. This allows the electric vehicle to transfer torque from the front to the rear axle at a higher rate when facing rapidly narrowing curves, thereby improving its response speed in emergency situations and ultimately enhancing its driving stability.

[0025] The faster the curvature of the road decreases, the faster the steering demand of the electric vehicle decreases. When the steering demand of the electric vehicle decreases rapidly, if the yaw torque of the electric vehicle does not decrease rapidly, the yaw torque will exceed the vehicle's needs. This excess yaw torque will cause the electric vehicle to fishtail. Therefore, in this embodiment, the ratio of the torque output from the front axle to the rear axle of the control drive system increases faster as the curvature of the road the electric vehicle travels decreases. This allows the rate of decrease in the yaw torque of the electric vehicle to match the rate of decrease in steering demand, thereby preventing the yaw torque from exceeding the vehicle's needs during corner exit and reducing the probability of fishtailing.

[0026] In one implementation of the first aspect, the control method further includes: during the entry and exit of the electric vehicle from a curve, after the accelerator pedal opening increases to a value greater than a first preset opening, controlling the sum of the torques output by the drive system to the front axle and rear axle to not increase with the increase of the accelerator pedal opening. Also, before the electric vehicle enters a curve and after it exits a curve, after the accelerator pedal opening increases to a value greater than a second preset opening, controlling the sum of the torques output by the drive system to the front axle and rear axle to not increase with the increase of the accelerator pedal opening. Wherein, the first preset opening is less than the second preset opening.

[0027] When the torque distributed from the drive system to the rear axle is increased to a higher level, the greater the sum of the torques output by the drive system to the front and rear axles, the more drive torque the rear axle actually receives from the drive system. Within a certain range, the greater the drive torque received by the rear axle, the greater the improvement in the rear axle's steering responsiveness in the electric vehicle. However, excessive drive torque on the rear axle can cause negative effects, leading to rear wheel sideslip, which in turn reduces the stability of the electric vehicle and causes driver panic.

[0028] To address this issue, the control method in this embodiment can reduce the upper limit of torque increase of the rear axle during cornering and cornering to be lower than the upper limit of torque increase before cornering and after cornering. This allows the electric vehicle to take safety measures before the rear wheels begin to slip, fundamentally avoiding dangerous situations.

[0029] In one implementation of the first aspect, the control method further includes: during the process of the electric vehicle entering a curve, when the road through which the electric vehicle is traveling curves to the left, controlling the torque output by the drive system to the left front wheel to be less than the torque output to the right front wheel, or controlling the torque output by the drive system to the left rear wheel to be less than the torque output to the right rear wheel, or controlling the torque output by the drive system to the left front wheel to be less than the torque output to the right front wheel and the torque output to the left rear wheel to be less than the torque output to the right rear wheel.

[0030] Electric vehicles experience increased steering demands when entering curves. At this time, shifting torque from the front axle to the rear axle can improve steering performance. However, adjusting the torque distribution between the front and rear axles offers limited improvement. When the road curvature increases further, other methods are needed to compensate for the increased steering demands. To address this, this embodiment controls the left and right wheels of either the front or rear axle to generate a torque difference based on the curvature of the road the electric vehicle is traveling on. This torque difference between the left and right wheels produces a yaw torque. The yaw torque generated by the torque difference between the left and right wheels assists in steering, thereby reducing the steering load on the two front axle wheels, further improving the steering performance of the electric vehicle, and ensuring stable driving.

[0031] In one implementation of the first aspect, the control method further includes: controlling the torque difference output by the drive system to the left front wheel and the right front wheel to increase as the curvature of the road increases, or controlling the torque difference output by the drive system to the left rear wheel and the right rear wheel to increase as the curvature of the road increases, or controlling the torque difference output by the drive system to the left front wheel and the right front wheel and the torque difference output to the left rear wheel and the right rear wheel to increase simultaneously.

[0032] The greater the curvature of the road, the greater the steering demand gap of the electric vehicle. Therefore, in this embodiment, the torque difference between the left and right front wheels or the left and right rear wheels of the control drive system increases with the curvature of the road. This allows the yaw moment generated by the torque difference between the left and right wheels of the electric vehicle to adapt to the actual steering demand gap of the electric vehicle, thereby improving the accuracy of electric vehicle control, avoiding discomfort to passengers due to excessive yaw moment, and enhancing passenger comfort.

[0033] In one implementation of the first aspect, the control method further includes: when the electric vehicle begins to enter a curve, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to begin decreasing. After a preset time following the electric vehicle's entry into the curve, when the steering wheel of the electric vehicle has not begun to turn, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to stop decreasing.

[0034] This embodiment determines the probability that an electric vehicle will actually require steering when it may need to, by observing whether the steering wheel rotates within a preset time after the electric vehicle begins to enter a curve. When the steering wheel does not rotate within the preset time after the electric vehicle begins to enter a curve, it indicates that the probability of the electric vehicle actually requiring steering is low. Therefore, the torque from the front wheels can be stopped from transferring to the rear wheels, thereby avoiding ineffective control of the electric vehicle.

[0035] Secondly, this application provides a controller for an electric vehicle. This controller, during the driving process before the electric vehicle enters a curve, controls the sum of the torques output by the drive system to the front and rear axles of the electric vehicle to vary with the accelerator pedal opening. During the curve entry process, before the steering wheel of the electric vehicle begins to turn, the controller controls the ratio of the torques output by the drive system to the front and rear axles to be less than the ratio of the torques output by the drive system to the front and rear axles during the driving process before the curve entry, and controls the sum of the torques output by the drive system to vary with the accelerator pedal opening.

[0036] Specifically, the curvature of the road traveled by the electric vehicle before entering the curve is less than the curvature of the road traveled by the electric vehicle during the curve entry process, and the curvature of the road traveled by the electric vehicle during the curve entry process increases from small to large.

[0037] In one implementation of the second aspect, the controller is further configured to: during the exit of a curve, before the steering wheel of the electric vehicle begins to return to center, increase the ratio of the torque output by the drive system to the front axle and the rear axle, and control the sum of the torque output by the drive system to change with the accelerator pedal opening. Wherein, during the exit of the curve, the curvature of the road traveled by the electric vehicle decreases from large to small.

[0038] In one implementation of the second aspect, the controller is further configured to: after the electric vehicle exits a curve, control the ratio of the torque output by the drive system to the front axle and the rear axle to be greater than the ratio of the torque output by the drive system to the front axle and the rear axle during the exit of the curve.

[0039] In one implementation of the second aspect, the controller is further configured to: during the process of the electric vehicle entering a curve, control the ratio of the torque output by the drive system to the front axle and the rear axle to decrease as the steering wheel of the electric vehicle rotates, and control the ratio of the torque output by the drive system to the front axle and the rear axle to remain unchanged after the steering wheel of the electric vehicle stops rotating.

[0040] In one implementation of the second aspect, the controller is further configured to: control the ratio of torque output by the drive system to the front axle and the rear axle to decrease as the road curvature indicated by the road curvature signal increases during the electric vehicle's entry into a curve.

[0041] In one implementation of the second aspect, the controller is further configured to: when the curvature of the road increases to a first curvature during the curve entry process, control the ratio of the torque output by the drive system to the front axle and the rear axle to be a first ratio. When the curvature of the road decreases to the first curvature during the curve exit process, control the ratio of the torque output by the drive system to the front axle and the rear axle to be a second ratio. The first ratio is less than the second ratio.

[0042] In one implementation of the second aspect, the controller is further configured to: during the electric vehicle's entry into a curve, the faster the curvature of the road the electric vehicle travels increases, the faster the ratio of the torque output by the drive system to the front axle and rear axle decreases. During the electric vehicle's exit from a curve, the faster the curvature of the road the electric vehicle travels decreases, the faster the ratio of the torque output by the drive system to the front axle and rear axle increases.

[0043] In one implementation of the second aspect, the controller is further configured to: during the entry and exit of the electric vehicle from a curve, after the accelerator pedal opening increases to a value greater than a first preset opening, control the sum of the torques output by the drive system to the front and rear axles to not increase with the increase of the accelerator pedal opening. Also, before the electric vehicle enters a curve and after it exits a curve, after the accelerator pedal opening increases to a value greater than a second preset opening, control the sum of the torques output by the drive system to the front and rear axles to not increase with the increase of the accelerator pedal opening. Wherein, the first preset opening is less than the second preset opening.

[0044] In one implementation of the second aspect, the controller is further configured to: control the torque output by the drive system to the left front wheel to be less than the torque output to the right front wheel when the road through which the electric vehicle is traveling bends to the left during the process of the electric vehicle entering a curve, and / or control the torque output by the drive system to the left rear wheel to be less than the torque output to the right rear wheel.

[0045] In one implementation of the second aspect, the controller is further configured to: control the torque difference output by the drive system to the left front wheel and the right front wheel to increase as the curvature of the road increases, and / or control the torque difference output by the drive system to the left rear wheel and the right rear wheel to increase as the curvature of the road increases.

[0046] In one implementation of the second aspect, the controller is further configured to: when the electric vehicle begins to enter a curve, control the ratio of the torque output by the drive system to the front axle and the rear axle to begin decreasing. After a preset time following the electric vehicle's entry into the curve, when the steering wheel of the electric vehicle has not begun to turn, control the ratio of the torque output by the drive system to the front axle and the rear axle to stop decreasing.

[0047] Thirdly, this application provides an electric vehicle including a drive system and a controller. The drive system is used to output torque to the front and rear axles of the electric vehicle. The controller is used to perform the control methods as described in the first aspect and various embodiments thereof.

[0048] For details on other beneficial effects, please refer to the beneficial effects described in the first aspect, which will not be repeated here. Attached Figure Description

[0049] Figure 1 is a schematic diagram of a vehicle architecture provided in an embodiment of this application;

[0050] Figure 2 is a schematic diagram of a drive system provided in an embodiment of this application;

[0051] Figure 3 is a schematic diagram of another driving system provided in an embodiment of this application;

[0052] Figure 4 is a vehicle control timing diagram provided in an embodiment of this application;

[0053] Figure 5 is a vehicle control flowchart provided in an embodiment of this application. Detailed Implementation

[0054] The technical solutions in this application will now be described in conjunction with the accompanying drawings. The detailed descriptions and drawings of the following embodiments are used to exemplarily illustrate the principles of this application, but should not be used to limit the scope of this application; that is, this application is not limited to the described embodiments.

[0055] It should be noted that, in this application, the terms "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or illustration. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0056] When a vehicle travels at high speed on a curved road, it relies primarily on the driver's actions to maintain stability. However, the driver's capabilities are limited, consisting mainly of steering and braking. In scenarios involving consecutive curves or sharp bends, not only is it difficult for the driver to achieve proper and precise control, but even if appropriate and precise control is achieved, the vehicle struggles to avoid understeer or oversteer through steering and braking, resulting in serious deficiencies in driving stability.

[0057] In one possible implementation, for four-wheel drive vehicles, the vehicle can actively distribute the drive torque to the front and rear wheels based on the steering wheel angle. By controlling the change in drive torque between the front and rear wheels with the steering wheel angle, the vehicle's cornering ability can be improved, thereby enhancing driving stability. However, the mechanical delay in collecting steering wheel angle data makes it difficult for the vehicle to obtain the real-time status of the curve, which may still result in the risk of understeer in high-speed scenarios.

[0058] To address the aforementioned issues, this application provides a control method, controller, and electric vehicle for an electric vehicle. After the electric vehicle begins to enter a curve but before the steering wheel begins to turn, the ratio of the torque output by the drive system to the front axle and the rear axle is pre-controlled to be less than the ratio of the torque output by the drive system to the front axle and the rear axle before the electric vehicle enters the curve. By proactively reducing the ratio of the torque output by the front axle and the rear axle, the electric vehicle is prepared for the increase of lateral force before the front wheels actually begin to increase lateral force, thereby improving the driving stability of the electric vehicle during curve entry.

[0059] The following section will introduce the vehicle architecture and system architecture on which this application is based.

[0060] Referring to Figure 1, which is a schematic diagram of a vehicle architecture provided in an embodiment of this application, the vehicle 10 may be an electric vehicle. As shown in Figure 1, the vehicle 10 includes a drive system 110, a braking system 120, an autonomous driving system 150, a power battery 130 connected to the drive system 110, and a vehicle controller 140 connected to the drive system 110, the braking system 120, and the autonomous driving system 150, respectively. The drive system 110 is used to drive the vehicle 10. The braking system 120 is used to brake the vehicle 10. The power battery 130 is used to provide electrical energy to the drive system 110. The vehicle controller 140 is used to control the drive system 110 to drive the vehicle 10 and to control the braking system 120 to brake the vehicle 10.

[0061] The four wheels of vehicle 10 can be divided into left front wheel, right front wheel, left rear wheel, and right rear wheel according to their position in vehicle 10. According to axle division, the left front wheel and right front wheel are on the same axle and connected via the front axle. The left rear wheel and right rear wheel are on the same axle and connected via the rear axle. According to position, the left front wheel and left rear wheel are on the same side (left side), and the right front wheel and right rear wheel are on the same side (right side). That is to say, in vehicle 10, the left front wheel and right front wheel are on the same axle, the left rear wheel and right rear wheel are on the same axle; the left front wheel and left rear wheel are on the same side, and the right front wheel and right rear wheel are on the same side.

[0062] In this application embodiment, the vehicle 10 can be any type of automobile, such as a sedan, truck, or passenger bus, or it can be a tricycle, two-wheeled vehicle, train, or other transportation device for carrying passengers or goods, or other types of vehicles powered by a power battery. This application embodiment does not limit this. The vehicle includes, but is not limited to, pure electric vehicles (pure EV / battery EV), hybrid electric vehicles (HEV), range-extended electric vehicles (REEV), plug-in hybrid electric vehicles (PHEV), and new energy vehicles (NEV).

[0063] The drive system 110 can be referred to as a powertrain. This application embodiment does not limit the specific type of the drive system 110; it is merely an example and not a limitation. The structure of the drive system 110 can be illustrated as a schematic diagram of a drive system in Figure 2. In Figure 2, the drive system 110 includes two drive motors 112 and a drive controller 111 connected to each of the two drive motors 112. The two drive motors 112 are connected to the front axle and the rear axle, respectively. The drive motor 112 connected to the front axle outputs torque to the front axle, and the drive motor 112 connected to the rear axle outputs torque to the rear axle. The drive controller 111 controls the two drive motors 112 to output drive torque to the front axle and the rear axle, respectively. In the drive system 110 shown in Figure 2, the sum of the torque output by the drive motor 112 on the front axle and the torque output by the drive motor 112 on the rear axle can be called the torque sum. The ratio of the torque distributed by the drive motor 112 to the rear axle is the ratio of the torque output by the drive motor 112 on the rear axle to the torque sum. The ratio of the torque distributed by the drive motor 112 to the front axle is the ratio of the torque output by the drive motor 112 on the front axle to the torque sum.

[0064] The structure of the drive system 110 can also be shown in the schematic diagram of another drive system in Figure 3. In Figure 3, the drive system 110 includes four drive motors 112 and a drive controller 111 connected to each of the four drive motors 112. Specifically, the four drive motors 112 can be wheel-side motors or wheel hub motors, connected to the four wheels of the vehicle 10 respectively, and used to output torque to the four wheels of the vehicle 10. The drive controller 111 is used to control the four drive motors 112 to output drive torque to the four wheels respectively. In the drive system 110 shown in Figure 3, the torque ratio distributed by the drive motors 112 to the rear axle is the ratio of the sum of the torques output by the drive motors 112 of the left and right rear wheels to the sum of the torques output by the drive motors 112 of all four wheels; the torque ratio distributed by the drive motors 112 to the front axle is the ratio of the sum of the torques output by the drive motors 112 of the left and right front wheels to the sum of the torques output by the drive motors 112 of all four wheels.

[0065] The braking system 120 can be either a hydraulic braking system or an electromechanical braking system. A hydraulic braking system uses brake fluid as an incompressible transmission medium, transmitting pedal force to the brake cylinders of each wheel via the master cylinder and brake lines to achieve braking. An electromechanical braking system eliminates the hydraulic lines, directly using a brake motor located at the wheel end to drive the brake calipers.

[0066] The power battery 130 in this embodiment can be a lithium-ion battery, lithium metal battery, lead-acid battery, nickel-cadmium battery, nickel-metal hydride battery, lithium-sulfur battery, lithium-air battery, or sodium-ion battery, etc., and this application does not limit its application to this type. In terms of scale, the power battery 130 in this embodiment can be a single cell, a battery module, or a battery pack, and this application does not limit its application to this type. The power battery 130 can also supply power to other electrical devices in the vehicle 10, such as the vehicle's air conditioning and in-vehicle media player.

[0067] The autonomous driving system 150 is an electronic system that uses sensors, cameras, radar, and computer control technology to help drivers drive more safely and easily. The autonomous driving system 150 includes a perception module and a control module. The perception module can be sensors such as cameras and radar, used to perceive the environment in which the vehicle 10 is located. The control module can be a microcomputer, used to control the vehicle 10 to drive automatically or assist the driver based on the environmental signals acquired by the perception module.

[0068] The control method of the electric vehicle 10 provided in this application will be described in detail below with reference to the vehicle 10 architecture shown in Figures 1 to 3 and a vehicle control timing diagram shown in Figure 4.

[0069] In Figure 4, t1 is the moment when vehicle 10 begins to enter the curve, t2 is the moment when the steering wheel begins to turn, t3 is the moment when the steering wheel stops turning, t4 is the moment when vehicle 10 begins to exit the curve, t5 is the moment when the steering wheel begins to turn back, and t6 is the moment when the vehicle finishes exiting the curve.

[0070] When vehicle 10 travels on a road, regardless of the type of road it is on, the road will always have a certain degree of curvature. However, when the curvature of the road is small, the vehicle does not need to turn and can maintain a straight line. (A preset curvature of 0.0001m is used.) -1 For example, roads with a curvature of less than 0.0001m -1 When the road curvature is greater than 0.0001m, it can be considered that the vehicle can maintain a straight line without turning; -1 When this occurs, it is considered a curve and a turn is required. The preset curvature can be 0.0001m. -1 In addition, it can also be 0.0002m -1 0.00001m -1 Alternatively, settings can be dynamically adjusted based on the actual road conditions.

[0071] In one embodiment, the driving process of vehicle 10 before entering a curve or during the curve can be distinguished by determining whether the curvature of the road traveled by vehicle 10 is less than a preset curvature. If the curvature of the road traveled by vehicle 10 is less than the preset curvature, this driving process can be considered as the driving process of vehicle 10 before entering a curve; if the curvature of the road traveled by vehicle 10 is greater than the preset curvature, this driving process can be considered as the driving process of vehicle 10 during the curve entry.

[0072] Before time t1, during the driving process of vehicle 10 before entering the curve, the vehicle can maintain straight-line travel. Vehicle 10 experiences almost no lateral force during travel, and the torque ratio output by drive system 110 to the front and rear axles can be kept constant. Simultaneously, when the driver depresses the accelerator pedal, the sum of the torques output by drive system 110 to the front and rear axles increases with the increase of the accelerator pedal opening; when the driver releases the accelerator pedal, the sum of the torques output by drive system 110 to the front and rear axles decreases with the decrease of the accelerator pedal opening.

[0073] During the cornering process of vehicle 10 starting from time t1, before time t2 when the steering wheel of vehicle 10 begins to turn, the ratio of the torque output to the front axle and rear axle of the control drive system 110 is less than the ratio of the torque output to the front axle and rear axle of the control drive system 110 during the driving process before vehicle 10 enters the corner. Simultaneously, when the driver depresses the accelerator pedal, the sum of the torque output to the front axle and rear axle of the control drive system 110 increases as the accelerator pedal opening increases; when the driver releases the accelerator pedal, the sum of the torque output to the front axle and rear axle of the control drive system 110 decreases as the accelerator pedal opening decreases.

[0074] Specifically, the ratio of the torque output by the drive system 110 to the front axle and the rear axle can refer to the ratio of the driving torque output by the drive motor 112 of the front axle to the driving torque output by the drive motor 112 of the rear axle.

[0075] The curvature of the road that vehicle 10 travels on during cornering can be greater than a preset curvature, and the curvature gradually increases as the vehicle travels. During cornering, the front wheels not only drive the vehicle but also steer it. The grip generated by the front wheels needs to simultaneously provide the longitudinal force required for forward movement and the lateral force required for steering. Therefore, the greater the actual longitudinal force of the front wheels, the smaller the lateral force allowed; conversely, the smaller the actual longitudinal force of the front wheels, the greater the lateral force allowed. The greater the allowed lateral force of the front wheels, the less likely the actual lateral force generated during steering will exceed the lateral force limit, and the less likely vehicle 10 will experience understeer due to sideslip.

[0076] In this embodiment, during the cornering process of vehicle 10, the ratio of torque output from the drive system 110 to the front axle and rear axle is less than the ratio during the initial cornering process. This allows for a heavier drive load on the rear wheels, reducing the burden on the front wheels. With the reduced drive load, the longitudinal force on the front wheels also decreases, allowing for a corresponding increase in the lateral force, which facilitates more effective steering. Simultaneously, the increased drive torque on the rear wheels increases the yaw moment of vehicle 10, further aiding in more aggressive cornering. Therefore, by using a smaller ratio of torque output from the front and rear axles, this embodiment enhances the cornering aggression of vehicle 10 while enabling the front wheels to more effectively perform steering during cornering, thus preventing understeer and ensuring the vehicle's stability.

[0077] Meanwhile, in this embodiment, before the steering wheel of vehicle 10 starts to turn and vehicle 10 actually enters the turning state, the torque ratio of the front axle and the rear axle is reduced in advance through forward control, so that vehicle 10 is prepared for the increase of lateral force before the front wheels actually start to increase lateral force, thereby further improving the smoothness and safety of vehicle 10 during the cornering process.

[0078] When vehicle 10 begins to enter a curve, it indicates that vehicle 10 may have a steering need. The steering wheel begins to turn, indicating that vehicle 10 has actually begun to turn. In the above embodiment, between time t1 when vehicle 10 begins to enter the curve and time t2 when the steering wheel begins to turn, the torque output from the front axle to the rear axle of the drive system 110 is transferred. This effectively means that when vehicle 10 may have a steering need, control measures are taken in advance to meet the steering needs of vehicle 10, thus providing proactive control before vehicle 10 actually begins to turn.

[0079] However, considering that after vehicle 10 begins to enter the curve at time t1, the driver may not intend to control vehicle 10 to steer, and the driver will not actually operate the steering wheel to turn it. Therefore, in one embodiment, at time t1 when vehicle 10 begins to enter the curve, the ratio of torque output by drive system 110 to the front axle and rear axle can be controlled to begin decreasing. After a preset time period following time t1 when vehicle 10 begins to enter the curve, if the steering wheel has not started to turn, the ratio of torque output by drive system 110 to the front axle and rear axle stops decreasing.

[0080] This embodiment determines the probability that vehicle 10 will actually require steering when it may need to, by checking whether the steering wheel rotates within a preset time after vehicle 10 begins to enter a curve. When the steering wheel does not rotate within the preset time after vehicle 10 begins to enter a curve, it indicates that the probability of vehicle 10 actually requiring steering is low. Therefore, the torque from the front wheels can be stopped from transferring to the rear wheels, thereby avoiding ineffective control of vehicle 10.

[0081] In one embodiment, to further optimize the torque distribution of vehicle 10, during the process of vehicle 10 entering a curve, before t2 when the steering wheel of vehicle 10 begins to turn, the ratio of the torque output by drive system 110 to the front axle and rear axle can be controlled to change with the road curvature of the road where vehicle 10 is located. The road curvature can be obtained through the road curvature signal acquired by autonomous driving system 150.

[0082] The autonomous driving system 150 is equipped with an image sensor that can acquire images of the road ahead of the vehicle 10. After acquiring the road image, the image sensor sends it to the controller of the autonomous driving system 150, which processes the image to obtain a road curvature signal that can be used to indicate the road curvature. After obtaining the road curvature signal, the autonomous driving system 150 sends it to the drive controller 111, enabling the drive controller 111 to control the ratio of torque output to the front axle and rear axle based on the road curvature.

[0083] In this embodiment, before the steering wheel of vehicle 10 starts to turn at time t2, the ratio of torque output from the front axle and the rear axle is adaptively adjusted according to the curvature of the road on which vehicle 10 is traveling. This allows vehicle 10 to adapt to the environment even when the steering wheel does not turn, providing vehicle 10 with a more precise torque distribution strategy and achieving smoother cornering.

[0084] In one embodiment, during the process of vehicle 10 entering a curve, after time t2 when the steering wheel of vehicle 10 begins to rotate, the ratio of the torque output by the control drive system 110 to the front axle and the rear axle decreases as the steering wheel angle increases, and the ratio of the torque output by the control drive system 110 to the front axle and the rear axle remains unchanged when the steering wheel stops rotating from time t3.

[0085] Once the steering wheel of vehicle 10 begins to turn, the steering of the front wheels is controlled by the driver's steering intention. The stronger the driver's steering awareness, the larger the steering wheel angle, and the heavier the steering task borne by the front wheels. Therefore, under these circumstances, the ratio of torque output from the drive system 110 to the front axle and rear axle can be controlled to increase as the steering wheel angle increases during steering wheel rotation and remain constant when the steering wheel stops turning. This synchronizes the torque distribution with the driver's steering operation, ensuring that the amount of torque distribution providing steering assistance is proportional to the driver's steering intention, thereby enhancing the driver's handling experience.

[0086] In one embodiment, during the process of vehicle 10 entering a curve, after time t2 when the steering wheel of vehicle 10 begins to turn, in order to maintain forward control of vehicle 10 and improve the smoothness of vehicle 10 cornering, the ratio of torque output by drive system 110 to the front axle and rear axle can be controlled to decrease as the road curvature indicated by the road curvature signal increases. That is, throughout the entire process of vehicle 10 entering a curve, including before and after the steering wheel begins to turn, the ratio of torque output by drive system 110 to the front axle and rear axle can be controlled to decrease as the road curvature indicated by the road curvature signal increases. In an optional embodiment, when steering controller 111 controls drive system 110 to decrease the ratio of torque output to the front axle and rear axle as the road curvature indicated by the road curvature signal increases, if the steering wheel stops turning, the ratio of torque output by drive system 110 to the front axle and rear axle should be kept constant so that the driving state of vehicle 10 matches the driver's control intention.

[0087] Furthermore, throughout the entire process of vehicle 10 entering a curve, the rate at which the ratio of torque output by drive system 110 to the front axle and rear axle decreases can vary with the rate at which the curvature of the road increases. Specifically, the faster the curvature of the road that vehicle 10 travels on increases, the faster the ratio of torque output by drive system 110 to the front axle and rear axle decreases.

[0088] The rapid increase in curvature of the road traversed by vehicle 10 indicates that the road is a rapidly narrowing curve, causing a drastic dynamic change in the driving environment of vehicle 10 within a short period. To cope with this rapid change, vehicle 10 needs to provide more effective steering responses. Therefore, in this embodiment, the rate of decrease in the ratio of torque output from the front axle to the rear axle by the control drive system 110 increases with the rate of increase in road curvature. This allows vehicle 10 to transfer torque from the front axle to the rear axle at a higher torque transfer rate when facing rapidly narrowing curves, thereby improving the vehicle 10's response speed in emergency situations and ultimately enhancing its driving stability.

[0089] As analyzed above, to improve the steering performance of vehicle 10, the torque transfer from the front axle to the rear axle can be controlled. Furthermore, for higher steering performance, the proportion of torque distributed to the rear axle from the drive system 110 should be higher. When the proportion of torque distributed to the rear axle from the drive system 110 is increased to a higher level, the sum of the torques output by the drive system 110 to the front and rear axles is greater, and the rear axle actually receives more drive torque from the drive system 110. Within a certain range, the greater the drive torque received by the rear axle, the greater the improvement in the rear axle's steering responsiveness to vehicle 10. However, excessive drive torque on the rear axle can have negative effects, causing the rear wheels to sideslip, thereby reducing the stability of vehicle 10 and causing driver panic.

[0090] Therefore, in one embodiment, before the vehicle 10 enters a curve, the sum of the torques output by the drive system 110 to the front and rear axles can be controlled to not increase with further increases in the accelerator pedal opening after the accelerator pedal opening reaches a second preset opening. During the curve entry process, the sum of the torques output by the drive system 110 to the front and rear axles can be controlled to not increase with further increases in the accelerator pedal opening after the accelerator pedal opening reaches a first preset opening less than the second preset opening. This embodiment, through this control method, ensures that the upper limit of torque increase on the rear axle during curve entry is lower than the upper limit of torque increase before curve entry, thereby enabling the vehicle 10 to take safety measures before the rear wheels begin to slip, fundamentally avoiding dangerous situations. The first preset opening can be 80%, 70%, or 75%, and the second preset opening can be 100% or 98%, etc.

[0091] To further improve the steering performance of vehicle 10, in addition to adjusting the torque distribution ratio between the front and rear axles, the drive torque of the wheels on both sides of the same axle can also be adjusted. Specifically, when vehicle 10 is entering a curve, if the road it is traveling on curves to the left, the torque output by the drive system 110 to the left front wheel is less than the torque output to the right front wheel, or the torque output by the drive system 110 to the left rear wheel is less than the torque output to the right rear wheel; if the road it is traveling on curves to the right, the torque output by the drive system 110 to the left front wheel is greater than the torque output to the right front wheel, or the torque output by the drive system 110 to the left rear wheel is greater than the torque output to the right rear wheel.

[0092] When vehicle 10 enters a curve, its steering demand increases. At this time, controlling the torque transfer from the front axle to the rear axle can improve the steering performance of vehicle 10. However, adjusting the torque distribution between the front and rear axles has limited effect on improving steering performance. When the curvature of the road increases further, other methods are needed to compensate for the increased steering demand. Therefore, this embodiment controls the left and right wheels of the front or rear axle to generate a torque difference based on the curvature of the road traversed by vehicle 10. This torque difference between the left and right wheels generates a yaw torque. The yaw torque generated by the torque difference between the left and right wheels assists in steering, thereby reducing the steering load on the two front axle wheels, further improving the steering performance of vehicle 10, and ensuring stable driving of vehicle 10.

[0093] In one embodiment, when adjusting the driving torque of the wheels on both sides of the same axle, the torque difference output by the drive system 110 to the left front wheel and the right front wheel can be controlled to increase as the curvature of the road increases, or the torque difference output by the drive system 110 to the left rear wheel and the right rear wheel can be controlled to increase as the curvature of the road increases.

[0094] The greater the curvature of the road, the greater the steering demand gap of vehicle 10. Therefore, in this embodiment, the torque difference between the left and right front wheels or the left and right rear wheels of the drive system 110 increases with the curvature of the road. This allows the yaw moment generated by the torque difference between the left and right wheels of vehicle 10 to adapt to the actual steering demand gap of vehicle 10, thereby improving the accuracy of vehicle 10 control, avoiding discomfort to passengers due to excessive yaw moment of vehicle 10, and improving passenger comfort.

[0095] As the driving process progresses, vehicle 10 will transition from entering to exiting a curve, and the curvature of the road it travels on will gradually decrease. During curve entry, the steering demand increases with the road curvature, leading to understeer in vehicle 10. During curve exit, vehicle 10 is prone to fishtailing. This application addresses this fishtailing issue by controlling the torque ratio between the front and rear axles during curve exit. Specifically:

[0096] In one embodiment, the drive controller 111 can control the ratio of the torque output by the drive system 110 to the front axle and the rear axle to increase after the vehicle 10 begins to exit the curve at time t4 and before the steering wheel of the vehicle 10 begins to return to center at time t5, and control the sum of the torque output by the drive system 110 to the front axle and the rear axle to change with the change of the accelerator pedal opening.

[0097] Steering wheel straightening is a turning action relative to the way the steering wheel is turned during the vehicle's (10's) entry into a curve. For example, if the steering wheel is turned to the left during the vehicle's (10's) entry into a curve, then in this embodiment, steering wheel straightening refers to the action of turning the steering wheel to the right; "before the steering wheel of the vehicle (10) begins to straighten" means before the steering wheel begins to turn to the right. If the steering wheel is turned to the right during the vehicle's (10's) entry into a curve, then in this embodiment, steering wheel straightening refers to the action of turning the steering wheel to the left; "before the steering wheel of the vehicle (10) begins to straighten" means before the steering wheel begins to turn to the left.

[0098] As vehicle 10 begins to exit a curve, the curvature of the road it travels on decreases, indicating that vehicle 10 may be prone to fishtailing. In this embodiment, the drive controller 111 increases the torque ratio between the front and rear axles in this situation. This reduces the drive load on the rear axle before the steering wheel begins to return to center and the fishtailing problem actually occurs, allowing the rear wheels to convert more of their grip into lateral force. This prevents the actual lateral force on the rear wheels from exceeding their allowable range during corner exit, thereby reducing the probability of vehicle 10 fishtailing.

[0099] When the ratio of the torque output by the drive system 110 to the front axle and the rear axle increases, specifically, the ratio of the torque output by the drive system 110 to the front axle and the rear axle increases faster as the curvature of the road through which the vehicle 10 travels decreases.

[0100] The faster the curvature of the road decreases, the faster the steering demand of vehicle 10 decreases. When the steering demand of vehicle 10 decreases rapidly, if the yaw torque of vehicle 10 cannot decrease rapidly, the actual yaw torque of vehicle 10 will exceed the yaw torque required by vehicle 10. This excess yaw torque will cause vehicle 10 to fishtail. Therefore, in this embodiment, the ratio of torque output from the drive system 110 to the front axle and rear axle increases faster as the curvature of the road traveled by vehicle 10 decreases. This allows the rate of decrease in yaw torque of vehicle 10 to match the rate of decrease in steering demand, thereby preventing the yaw torque of vehicle 10 from exceeding its requirements during corner exit and reducing the probability of fishtailing.

[0101] During the exit of a corner by vehicle 10, the drive system 110 gradually transfers torque from the rear axle to the front axle, causing the torque ratio distributed to the rear axle from the drive system 110 to gradually decrease from a high level to a low level. This transition from high to low levels is a gradual process, during which the torque ratio of the rear axle will remain at a relatively high level for a period of time. However, when the torque ratio of the rear axle is at a high level, the greater the sum of the torques output by the drive system 110 to the front and rear axles, the more drive torque the rear axle actually receives from the drive system 110. Excessive drive torque on the rear axle can cause the rear wheels to sideslip.

[0102] Therefore, in one embodiment, during the exit of a curve by vehicle 10, the sum of the torques output by the drive system 110 to the front and rear axles can be controlled to not increase with further increases in the accelerator pedal opening after the accelerator pedal opening reaches a first preset opening; after vehicle 10 exits a curve, the sum of the torques output by the drive system 110 to the front and rear axles can be controlled to not increase with further increases in the accelerator pedal opening after the accelerator pedal opening reaches a second preset opening greater than the first preset opening. This embodiment, through this control method, ensures that the upper limit of torque increase on the rear axle during the exit of a curve is lower than the upper limit of torque increase after exiting a curve, preventing the rear axle from sideslipping due to excessive drive torque during exiting a curve. This allows vehicle 10 to take safety measures before the rear wheels begin to slip, fundamentally avoiding dangerous situations.

[0103] The steering requirements of vehicle 10 vary when driving on roads with different curvatures. The embodiments described above adjust the torque ratio of the drive system 110 output to the front and rear axles during cornering and exiting corners. Essentially, this is to match the torque ratio of the front and rear axles with the steering requirements of vehicle 10, thereby preventing understeer due to a mismatch between the torque ratio and steering requirements during cornering, and preventing sideslip due to a mismatch between the torque ratio and steering requirements during corner exiting corners.

[0104] However, the dynamic requirements of vehicle 10 are not only determined by its steering requirements but also influenced by its body posture requirements. Due to inertia, vehicle 10 tends to shift outwards during cornering and inwards during cornering. Therefore, to accommodate these different body postures, when the road curvature increases to a first curvature during cornering, the ratio of torque output from the drive system 110 to the front and rear axles can be set to a first ratio; when the road curvature decreases to the first curvature during cornering, the ratio of torque output from the drive system 110 to the front and rear axles can be set to a second ratio. The first ratio is less than the second ratio, and the first curvature can be any curvature value of the road.

[0105] In this embodiment, when the vehicle 10 is traveling on a road with the same curvature, the drive system 110 is controlled to output different torque ratios to the front axle and the rear axle according to the different attitudes of the vehicle 10 during the entry and exit of the curve. This makes the torque ratio of the front axle and the rear axle no longer simply follow the curvature change, but also take into account the dynamic process direction of the vehicle 10 under the curvature. This provides a more precise torque distribution scheme for the vehicle 10, thereby further improving the driving stability of the vehicle 10.

[0106] As vehicle 10 exits the curve, the road curvature gradually decreases. When the road curvature decreases to less than a preset curvature, vehicle 10 completes its exit from the curve. After time t6, when vehicle 10 exits the curve, it can be assumed that vehicle 10 is traveling on a straight road. At this point, vehicle 10 will regain the driving stability it had before entering the curve. Therefore, the ratio of torque output from the drive system 110 to the front axle and rear axle can be controlled to be greater than the ratio of torque output from the drive system 110 to the front axle and rear axle during the exit of the curve, making vehicle 10 more biased towards front-wheel drive. When accelerating in a straight line, the front-wheel drive bias of vehicle 10 will create a tendency to force the front wheels to straighten, thus ensuring the stability of the front wheels when traveling on a straight road.

[0107] Next, referring to the vehicle control flowchart shown in Figures 4 and 5, the control process of vehicle 10 before entering the curve, during the curve entry process, during the curve exit process, and after the curve exit will be described in this application. Specifically:

[0108] At the beginning of this control flow, step S101 is executed first.

[0109] Step S101: Obtain the curvature of the road traveled by vehicle 10.

[0110] Step S102: Determine whether the curvature of the road is greater than the preset curvature.

[0111] When the curvature of the road is less than or equal to the preset curvature, it indicates that the vehicle 10 is in the process of driving before entering the curve, and at this time, the process can be transferred from step S102 to step S103.

[0112] When the curvature of the road is greater than the preset curvature, it indicates that the vehicle 10 is in the process of entering a curve, and at this time, the process can be transferred from step S102 to step S104.

[0113] In step S103, the sum of the torques output by the control drive system 110 to the front and rear axles of the vehicle 10 varies with the change in the accelerator pedal opening.

[0114] After step S103 is completed, you can return to step S101 and obtain the curvature of the road traversed by vehicle 10 again.

[0115] In step S104, the ratio of the torque output by the drive system 110 to the front axle and the rear axle decreases as the curvature of the road increases.

[0116] After step S104 is completed, proceed to step S105.

[0117] Step S105: Determine whether the steering wheel of vehicle 10 has started to turn.

[0118] If the steering wheel of vehicle 10 starts to turn, proceed from step S105 to step S106.

[0119] If the steering wheel does not start turning, return from step S105 to step S104, and repeat steps S104 and S105 until the steering wheel starts turning.

[0120] In step S106, the ratio of the torque output by the drive system 110 to the front axle and the rear axle decreases as the steering wheel angle increases.

[0121] After step S106, step S107 is executed to determine whether the curvature of the road has decreased.

[0122] If the curvature of the road begins to decrease, it indicates that vehicle 10 has entered the exit process from the process of entering the curve, and at this time, we can proceed from step S107 to step S108.

[0123] If the curvature of the road does not begin to decrease, it indicates that vehicle 10 is still in the process of entering the curve, and at this time, we can return from step S107 to step S106.

[0124] In step S108, before the steering wheel of the vehicle 10 begins to return to center, the ratio of the torque output by the drive system 110 to the front axle and the rear axle is increased.

[0125] After step S108, step S109 is executed to determine whether the curvature of the road is greater than the preset curvature.

[0126] If the curvature of the road is greater than the preset curvature, it indicates that vehicle 10 is still in the process of exiting the curve. At this time, you can return from step S109 to step S108.

[0127] If the curvature of the road is less than or equal to the preset curvature, it indicates that vehicle 10 is currently in the process of driving after exiting a curve. At this time, the process can be transferred from step S109 to step S110.

[0128] In step S110, the ratio of the torque output by the drive system 110 to the front axle and the rear axle is greater than the ratio of the torque output by the drive system 110 to the front axle and the rear axle during the process of the vehicle 10 exiting the curve.

[0129] After step S110 is completed, the current control flow ends.

[0130] In addition to steps S101 to S110 shown in Figure 5, steps S101 to S110 in Figure 5 can be modified by deleting, replacing, or adding other steps according to the control methods in various embodiments of this application, resulting in a control flow different from that in Figure 5. These modified control flows, as long as they conform to the basic control logic, should be considered to be within the scope of protection of this application.

[0131] In this embodiment of the application, a controller for an electric vehicle is also provided, wherein the control method executed by the controller corresponds to the control function implemented by the control method related to Figures 1-5 above.

[0132] Specifically, the controller is used for:

[0133] During the initial driving phase before the electric vehicle enters a curve, the sum of the torques output by the control drive system to the front and rear axles varies with the accelerator pedal opening. During the curve entry process, before the steering wheel begins to turn, the ratio of the torques output by the control drive system to the front and rear axles is less than the ratio of the torques output by the drive system to the front and rear axles during the initial driving phase before the curve entry, and the sum of the torques output by the control drive system to the front and rear axles varies with the accelerator pedal opening.

[0134] Specifically, the curvature of the road traveled by the electric vehicle before entering the curve is less than the curvature of the road traveled by the electric vehicle during the curve entry process, and the curvature of the road traveled by the electric vehicle during the curve entry process increases from small to large.

[0135] Optionally, the controller is also used to: during the exit of a curve, before the steering wheel of the electric vehicle begins to return to center, increase the ratio of the torque output by the drive system to the front axle and the rear axle, and control the sum of the torque output by the drive system to change with the accelerator pedal opening. During the exit of the curve, the curvature of the road traveled by the electric vehicle decreases from maximum to minimum.

[0136] Optionally, the controller is also used to: after the electric vehicle exits a curve, control the ratio of the torque output by the drive system to the front axle and the rear axle to be greater than the ratio of the torque output by the drive system to the front axle and the rear axle during the exit of the curve.

[0137] Optionally, the controller is also used to: during the process of the electric vehicle entering a curve, control the ratio of the torque output of the drive system to the front axle and the rear axle to decrease as the steering wheel of the electric vehicle rotates, and control the ratio of the torque output of the drive system to the front axle and the rear axle to remain unchanged after the steering wheel of the electric vehicle stops rotating.

[0138] Optionally, the controller is also configured to: during the process of the electric vehicle entering a curve, control the ratio of the torque output by the drive system to the front axle and the rear axle to decrease as the road curvature indicated by the road curvature signal increases.

[0139] Optionally, the controller is also configured to: when the curvature of the road increases to a first curvature during the entry into a curve, control the ratio of the torque output by the drive system to the front axle and the rear axle to a first ratio. When the curvature of the road decreases to the first curvature during the exit from a curve, control the ratio of the torque output by the drive system to the front axle and the rear axle to a second ratio; the first ratio is less than the second ratio.

[0140] Optionally, the controller is also configured to: during the electric vehicle's entry into a curve, the faster the curvature of the road the electric vehicle travels increases, the faster the ratio of torque output from the drive system to the front axle and rear axle decreases. During the electric vehicle's exit from a curve, the faster the curvature of the road the electric vehicle travels decreases, the faster the ratio of torque output from the drive system to the front axle and rear axle increases.

[0141] Optionally, the controller is further configured to: during the entry and exit of the electric vehicle from a curve, after the accelerator pedal opening increases to a value greater than a first preset opening, control the sum of the torques output by the drive system to the front and rear axles to not increase with the increase of the accelerator pedal opening. Also, before the electric vehicle enters a curve and after it exits a curve, after the accelerator pedal opening increases to a value greater than a second preset opening, control the sum of the torques output by the drive system to the front and rear axles to not increase with the increase of the accelerator pedal opening. Wherein, the first preset opening is less than the second preset opening.

[0142] Optionally, the controller is also used to: control the torque output by the drive system to the left front wheel to be less than the torque output to the right front wheel when the road through which the electric vehicle is traveling bends to the left during the process of the electric vehicle entering a curve, and / or control the torque output by the drive system to the left rear wheel to be less than the torque output to the right rear wheel.

[0143] Optionally, the controller is also used to: control the torque difference output by the drive system to the left front wheel and the right front wheel to increase as the curvature of the road increases, and / or control the torque difference output by the drive system to the left rear wheel and the right rear wheel to increase as the curvature of the road increases.

[0144] Optionally, the controller is also configured to: control the ratio of torque output from the drive system to the front axle and rear axle to begin decreasing when the electric vehicle begins to enter a curve; and control the ratio of torque output from the drive system to stop decreasing after a preset time following the start of the curve, when the steering wheel of the electric vehicle has not begun to turn.

[0145] In this embodiment of the application, an electric vehicle is also provided. The electric vehicle includes a drive system and a controller. The drive system is used to output torque to the front axle and rear axle of the electric vehicle. The control method executed by the controller corresponds to the control function implemented by the control method related to Figures 1-5 above.

[0146] For more detailed information on controllers and electric vehicles, please refer to the description of electric vehicle control methods in Figures 1-5 above.

[0147] In the embodiments of this application, the words "exemplary," "for example," etc., are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of the term "exemplary" is intended to present the concept in a concrete manner.

[0148] It should be understood that the term "embodiment" used throughout this specification means that a specific feature, structure, or characteristic related to an embodiment is included in at least one embodiment of this application. Therefore, various embodiments throughout this specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0149] It should also be understood that in this application, "when," "if," "in the circumstances of," and "if" all refer to a situation where a corresponding action will be taken under certain objective circumstances, and are not time-limited. They do not require the device to perform a judgment action, nor do they imply any other limitations. Furthermore, in this application, the descriptions of conditions such as "when," "if," "in the circumstances of," and "if" can be understood as necessary conditions, without limiting whether the condition is a sufficient condition or a necessary and sufficient condition. For example, "in the case of A, execute B" can be understood as "if at least A is satisfied, execute B."

[0150] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for an electric vehicle, characterized in that, The control method is used to control the drive system of the electric vehicle to adjust the torque distribution between the front and rear axles of the electric vehicle during cornering. The control method includes: during the electric vehicle's travel before entering the corner, controlling the sum of the torques output by the drive system to the front and rear axles of the electric vehicle to vary with the accelerator pedal opening; during the electric vehicle's cornering process, before the steering wheel of the electric vehicle begins to turn, controlling the ratio of the torques output by the drive system to the front and rear axles to be less than the ratio of the torques output by the drive system to the front and rear axles during the travel before the electric vehicle entered the corner, and controlling the sum of the torques output by the drive system to the front and rear axles to vary with the accelerator pedal opening; wherein the curvature of the road traveled by the electric vehicle before entering the corner is less than the curvature of the road traveled by the electric vehicle during cornering, and the curvature of the road traveled by the electric vehicle during cornering increases from small to large.

2. The control method according to claim 1, characterized in that, The control method further includes: during the process of the electric vehicle exiting a curve, before the steering wheel of the electric vehicle begins to return to center, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to increase, and controlling the sum of the torque output by the drive system to the front axle and the rear axle to change with the change of the accelerator pedal opening; wherein, during the process of the electric vehicle exiting a curve, the curvature of the road traveled by the electric vehicle decreases from large to small.

3. The control method according to claim 2, characterized in that, The control method further includes: after the electric vehicle exits the curve, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to be greater than the ratio of the torque output by the drive system to the front axle and the rear axle during the electric vehicle's exit from the curve.

4. The control method according to claim 1, characterized in that, The control method further includes: during the process of the electric vehicle entering a curve, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to decrease as the steering wheel of the electric vehicle rotates, and controlling the ratio of the torque output by the drive system to the front axle and the rear axle to remain unchanged after the steering wheel of the electric vehicle stops rotating.

5. The control method according to claim 1, characterized in that, The electric vehicle includes an autonomous driving system, which is used to acquire the road curvature signal traversed by the electric vehicle. The control method further includes: during the process of the electric vehicle entering a curve, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to decrease as the road curvature indicated by the road curvature signal increases.

6. The control method according to claim 2, characterized in that, The control method further includes: during the process of the electric vehicle entering a curve, when the curvature of the road through which the electric vehicle travels increases to a first curvature, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to be a first ratio; during the process of the electric vehicle exiting a curve, when the curvature of the road through which the electric vehicle travels decreases to the first curvature, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to be a second ratio; the first ratio is less than the second ratio.

7. The control method according to claim 2, characterized in that, The control method further includes: during the process of the electric vehicle entering a curve, the faster the curvature of the road through which the electric vehicle travels increases, the faster the ratio of the torque output by the drive system to the front axle and the rear axle decreases; during the process of the electric vehicle exiting a curve, the faster the curvature of the road through which the electric vehicle travels decreases, the faster the ratio of the torque output by the drive system to the front axle and the rear axle increases.

8. The control method according to claim 1, characterized in that, The control method further includes: during the process of the electric vehicle entering and exiting a curve, after the accelerator pedal opening increases to a value greater than a first preset opening, controlling the sum of the torques output by the drive system to the front axle and rear axle not to increase with the increase of the accelerator pedal opening; before the electric vehicle enters and after the electric vehicle exits a curve, after the accelerator pedal opening increases to a value greater than a second preset opening, controlling the sum of the torques output by the drive system to the front axle and rear axle not to increase with the increase of the accelerator pedal opening; wherein, the first preset opening is less than the second preset opening.

9. The control method according to claim 1, characterized in that, The control method further includes: during the process of the electric vehicle entering a curve, when the road through which the electric vehicle is traveling curves to the left, controlling the torque output by the drive system to the left front wheel to be less than the torque output to the right front wheel, and / or controlling the torque output by the drive system to the left rear wheel to be less than the torque output to the right rear wheel.

10. The control method according to claim 9, characterized in that, The control method further includes: controlling the difference in torque output by the drive system to the left front wheel and the right front wheel to increase as the curvature of the road increases, and / or controlling the difference in torque output by the drive system to the left rear wheel and the right rear wheel to increase as the curvature of the road increases.

11. The control method according to claim 1, characterized in that, The control method further includes: when the electric vehicle begins to enter a curve, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to begin to decrease; and after a preset time after the electric vehicle begins to enter a curve, when the steering wheel of the electric vehicle has not started to turn, controlling the ratio of the torque output by the drive system to the front axle and the rear axle to stop decreasing.

12. A controller for an electric vehicle, characterized in that, The controller is configured to: during the driving process before the electric vehicle enters a curve, control the sum of the torques output by the drive system to the front and rear axles of the electric vehicle to vary with the accelerator pedal opening; during the electric vehicle entering a curve, before the steering wheel of the electric vehicle begins to turn, control the ratio of the torques output by the drive system to the front and rear axles to be less than the ratio of the torques output by the drive system to the front and rear axles during the driving process before the electric vehicle enters a curve, and control the sum of the torques output by the drive system to the front and rear axles to vary with the accelerator pedal opening; wherein the curvature of the road traveled by the electric vehicle before entering a curve is less than the curvature of the road traveled by the electric vehicle during entering a curve, and the curvature of the road traveled by the electric vehicle during entering a curve increases from small to large.

13. The controller according to claim 12, characterized in that, The controller is further configured to: during the process of the electric vehicle exiting a curve, before the steering wheel of the electric vehicle begins to return to center, control the ratio of the torque output by the drive system to the front axle and the rear axle to increase, and control the sum of the torque output by the drive system to the front axle and the rear axle to change with the change of the accelerator pedal opening; wherein, during the process of the electric vehicle exiting a curve, the curvature of the road traveled by the electric vehicle decreases from large to small.

14. The controller according to claim 12, characterized in that, The controller is also configured to: during the process of the electric vehicle entering a curve, control the ratio of the torque output by the drive system to the front axle and the rear axle to decrease as the steering wheel of the electric vehicle rotates, and control the ratio of the torque output by the drive system to the front axle and the rear axle to remain unchanged after the steering wheel of the electric vehicle stops rotating.

15. An electric vehicle, characterized in that, The electric vehicle includes a drive system and a controller, the drive system being used to output drive torque to the front axle and rear axle of the electric vehicle, and the controller being used to execute the control method of the electric vehicle as described in any one of claims 1-11.

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