Control method for coordination of timely four-wheel-drive torque of electric vehicle, program product and vehicle

Abstract

The invention discloses a control method and a program product for coordination of timely four-wheel-drive torque of an electric vehicle and the vehicle, and belongs to the technical field of vehicle control. According to the method, the electric vehicle is configured in the mode that a front axle is driven by an asynchronous motor and a rear axle is driven by a synchronous motor. Considering that in the zero-crossing control stage of the asynchronous motor, the torque rising slope is small, and at the moment, a large front axle demand torque is requested immediately, the phenomenon that acceleration pause is brought due to the fact that zero-crossing response of the asynchronous motor of a front axle is not in time and the torque of a rear axle is decreased too fast, and the driving smoothness is affected can occur. Therefore, the torque of the asynchronous motor is slowly increased by adding a pre-calibrated zero-crossing demand torque curve, and when the actual torque of the asynchronous motor is larger than or equal to the first preset torque value, namely after zero crossing of the asynchronous motor is completed, the transfer from the two-wheel drive torque to the four-wheel drive torque is rapidly completed; the driving jerking feeling brought in the process of switching from the two-wheel-drive working mode to the four-wheel-drive working mode can be avoided, and the driving experience is improved.

Description

Technical Field

[0001] The present application belongs to the field of vehicle control technology, and in particular, relates to a control method, program product and vehicle for timely four-wheel drive torque coordination of an electric vehicle. Background Art

[0002] With the rapid development of the automobile industry and the increasing awareness of green environmental protection in modern society, electric vehicles are being accepted by more and more people. Different driving environments and driving needs may require different vehicle performance and energy management. In order to adapt to different road conditions and driving needs, electric vehicles are usually equipped with working modes including two-wheel drive mode and four-wheel drive mode.

[0003] However, when switching from two-wheel drive mode to four-wheel drive mode, the slope of the torque rise curve of the asynchronous motor on the front axle is small during the zero-crossing control stage. If a larger front axle torque is requested immediately at this time, there will be a sense of acceleration frustration due to the untimely zero-crossing response of the front axle motor and the rapid drop in rear axle torque, affecting driving smoothness. Summary of the invention

[0004] The embodiments of the present application provide a control method, program product and vehicle for timely four-wheel drive torque coordination of an electric vehicle, which can solve the driving frustration caused by the timely four-wheel drive control process and improve the driving experience.

[0005] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0006] According to a first aspect of an embodiment of the present application, a control method for timely four-wheel drive torque coordination of an electric vehicle is provided, wherein the electric vehicle is configured such that the front axle is driven by an asynchronous motor and the rear axle is driven by a synchronous motor, and the method comprises:

[0007] When it is detected that the driving condition satisfies the switching from the two-wheel drive working mode to the four-wheel drive working mode, requesting the electric vehicle to switch from the two-wheel drive working mode to the four-wheel drive working mode, and controlling the working mode of the asynchronous motor to switch from the standby mode to the torque mode;

[0008] Control the asynchronous motor to enter the gear preload stage, control the asynchronous motor to provide the gear preload force of the front axle, and linearly filter the torque distribution ratio to 0, so as to control the synchronous motor to bear all the required torque of the vehicle driving, wherein the filtering parameters are related to the current driving condition;

[0009] Controlling the asynchronous motor to provide torque according to a pre-calibrated zero-crossing demand torque curve, and adjusting the torque distribution ratio to a first target distribution ratio, so as to control the vehicle driving demand torque to be borne by the asynchronous motor and the synchronous motor in proportion, wherein the first target distribution ratio is associated with the pre-calibrated zero-crossing demand torque curve;

[0010] When it is detected that the actual torque of the asynchronous motor is greater than or equal to a first preset torque value, the control is switched from the two-wheel drive working mode to the four-wheel drive working mode.

[0011] In some embodiments of the present application, based on the aforementioned scheme, the pre-calibrated zero-crossing demand torque curve is a curve showing the change of the magnitude of the zero-crossing demand torque of the asynchronous motor over time, and the first target allocation ratio corresponding to the current moment is equal to the ratio of the zero-crossing demand torque of the asynchronous motor corresponding to the current moment to the driving demand torque of the whole vehicle corresponding to the current moment.

[0012] In some embodiments of the present application, based on the above-mentioned solution, the pre-calibrated zero-crossing demand torque curve is associated with the driving condition, and different driving conditions correspond to different pre-calibrated zero-crossing demand torque curves.

[0013] In some embodiments of the present application, based on the above solution, after controlling the working mode of the asynchronous motor to switch from the standby mode to the torque mode, the method further includes:

[0014] The asynchronous motor is controlled to provide the front axle with a gear preload force.

[0015] In some embodiments of the present application, based on the above scheme, the method further includes:

[0016] When it is detected that the driving condition satisfies the switching from the four-wheel drive working mode to the two-wheel drive working mode, requesting the electric vehicle to switch from the four-wheel drive working mode to the two-wheel drive working mode, and controlling the front axle torque to migrate to the rear axle;

[0017] Controlling the synchronous motor to provide torque according to a pre-calibrated rear-drive request torque curve, and adjusting the torque distribution ratio to a second target distribution ratio, so as to control the vehicle driving demand torque to be borne by the asynchronous motor and the synchronous motor in proportion, wherein the second target distribution ratio is associated with the pre-calibrated rear-drive request torque curve;

[0018] When it is detected that the actual torque of the synchronous motor is greater than or equal to the second preset torque value, the torque distribution ratio is linearly filtered to 0 to control the whole vehicle driving demand torque to be borne entirely by the synchronous motor, wherein the filtering parameters are related to the current driving conditions.

[0019] In some embodiments of the present application, based on the aforementioned scheme, the pre-calibrated rear-wheel drive request torque curve is a curve showing the change in the magnitude of the synchronous motor rear-wheel drive request torque over time, and the second target allocation ratio corresponding to the current moment is equal to 1 minus the ratio of the synchronous motor rear-wheel drive request torque corresponding to the current moment to the vehicle driving demand torque corresponding to the current moment.

[0020] In some embodiments of the present application, based on the above solution, the second target allocation ratio floats within a preset range, and when the second target allocation ratio is not within the preset range, the method further includes:

[0021] The pre-calibrated rear-drive request torque curve is modified based on the preset range.

[0022] In some embodiments of the present application, based on the above solution, after adjusting the torque distribution ratio to 0 to control the whole vehicle driving demand torque to be borne entirely by the synchronous motor, the method further includes:

[0023] When it is detected that the actual torque of the asynchronous motor is 0, the working mode of the asynchronous motor is controlled to switch from the torque mode to the standby mode.

[0024] In some embodiments of the present application, based on the above-mentioned solution, the pre-calibrated rear-wheel drive request torque curve is associated with the driving condition, and different driving conditions correspond to different pre-calibrated rear-wheel drive request torque curves.

[0025] According to a second aspect of an embodiment of the present application, a computer program product is provided, which includes computer instructions stored in a computer-readable storage medium and suitable for being read and executed by a processor, so that a computer device having the processor executes the method described in the first aspect of the embodiment of the present application.

[0026] According to a third aspect of an embodiment of the present application, a vehicle is provided, comprising one or more processors and one or more memories, wherein at least one computer program instruction is stored in the one or more memories, and the at least one computer program instruction is loaded and executed by the one or more processors to implement the method described in any embodiment of the first aspect above.

[0027] Based on the technical solution proposed in this application, the electric vehicle is configured such that the front axle is driven by an asynchronous motor and the rear axle is driven by a synchronous motor. When it is detected that the driving condition meets the switching from the two-wheel drive working mode to the four-wheel drive working mode, the electric vehicle is requested to switch from the two-wheel drive working mode to the four-wheel drive working mode, and the working mode of the asynchronous motor is controlled to switch from the standby mode to the torque mode. Then the asynchronous motor is controlled to enter the gear preload stage, the gear preload force of the front axle provided by the asynchronous motor is controlled, and the torque distribution ratio is adjusted to 0, so as to control the whole vehicle driving demand torque to be borne by the synchronous motor, so as to eliminate the impact and frustration caused by the asynchronous motor gear. Considering that the torque rising slope of the asynchronous motor is small in the zero-crossing control stage, if a larger front axle demand torque is requested immediately at this time, there will be a sense of acceleration frustration due to the untimely zero-crossing response of the asynchronous motor of the front axle and the excessive decrease of the rear axle torque, which affects the driving smoothness. Therefore, the present application controls the asynchronous motor to provide torque according to the pre-calibrated zero-crossing demand torque curve, and adjusts the torque distribution ratio to the first target distribution ratio, so as to control the whole vehicle driving demand torque to be borne by the asynchronous motor and the synchronous motor in proportion. That is, by adding a pre-calibrated zero-crossing demand torque curve to make the torque of the asynchronous motor rise slowly, when the actual torque of the asynchronous motor is greater than or equal to the first preset torque value, that is, after the asynchronous motor completes zero crossing, the migration of the two-wheel drive to four-wheel drive torque is quickly completed, which can solve the driving frustration caused by the switching from the two-wheel drive working mode to the four-wheel drive working mode and improve the driving experience.

[0028] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0030] Figure 1 This is a first flow chart of a control method for timely four-wheel drive torque coordination of an electric vehicle provided by an embodiment of the present application.

[0031] Figure 2 It is a schematic diagram of the torque coordination process of switching from a two-wheel drive working mode to a four-wheel drive working mode.

[0032] Figure 3 This is the second flow chart of the control method for timely four-wheel drive torque coordination of an electric vehicle provided by an embodiment of the present application.

[0033] Figure 4It is a schematic diagram of the torque coordination process of switching from the four-wheel drive working mode to the two-wheel drive working mode.

[0034] Figure 5 This is the hardware structure of a computer program product provided in one embodiment of the present application.

[0035] Figure 6 It is a schematic diagram of the structure of a vehicle in one embodiment of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0038] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0039] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0040] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0041] In order to enable those skilled in the art to better understand the present application, the application scenarios involved in the present application are first briefly described.

[0042] Electric vehicles will choose a solution with an asynchronous motor on the front axle and a synchronous motor on the rear axle to drive the whole vehicle in four-wheel drive configuration, and realize timely four-wheel drive function through strategic control, making full use of the advantages and disadvantages of synchronous and asynchronous motors to achieve the effect of improving battery life and reducing costs.

[0043] Synchronous motors have high operating efficiency and good operating stability, but they are expensive and have large structural dimensions.

[0044] In comparison, asynchronous motors have a simple structure, high reliability, and low price, but they have low operating efficiency and high noise.

[0045] The biggest difference between the two motors in terms of electronic control is that the synchronous motor cannot be requested to open the tube at high speed, otherwise the motor speed will increase and generate a large back electromotive force, and the current will flow into the power supply through the freewheeling diode, which may cause excessive voltage and capacitor damage. However, the asynchronous motor does not have the above concerns, so the timely four-wheel drive function is realized by configuring the front axle asynchronous and rear axle synchronous motor solution, reducing costs while improving endurance.

[0046] New energy electric vehicles equipped with front-axle asynchronous motors and rear-axle synchronous motors can achieve the vehicle's timely four-wheel drive function through control strategies. The use of asynchronous motors on the front axle greatly reduces the cost of the vehicle, and through the optimization of the vehicle system efficiency, the control is implemented in the low-efficiency area of ​​the asynchronous motor. The vehicle's driving torque is all achieved by the rear-axle synchronous motor, and the vehicle behaves as a single rear-wheel drive. At this time, the front-axle asynchronous motor works in standby mode and the speed follows the rotation. When a large torque request (such as climbing a hill or a large throttle) is identified or the rear-axle driving capacity (driving capacity and feedback capacity) does not meet the vehicle's driving needs, the front-axle asynchronous motor is requested to open the tube (that is, the motor mode is switched from standby mode to torque mode), and the vehicle switches to four-wheel drive.

[0047] However, when switching from the two-wheel drive mode to the four-wheel drive mode, the slope of the torque rise curve of the asynchronous motor of the front axle is small during the zero-crossing control stage. If a larger front axle required torque is immediately requested at this time, there will be a sense of acceleration frustration due to the untimely zero-crossing response of the front axle motor and the excessive decrease of the rear axle torque, which affects the driving smoothness. When switching from the four-wheel drive mode to the two-wheel drive mode, the front axle torque needs to be transferred to the rear axle, and the front axle torque will increase from negative torque to 0, or the front axle torque will decrease from positive torque to 0 and the rear axle torque needs to compensate for the front axle exit torque and meet the required torque of the vehicle. However, there may be a large difference between the slope of a certain section of the torque unloading curve of the front axle (larger) and the slope of the corresponding section of the torque compensation curve of the rear axle (smaller), resulting in the rear axle being unable to respond to the front axle exit torque in time, which will cause a sense of deceleration frustration.

[0048] Based on this, an embodiment of the present application provides a control method for timely four-wheel drive torque coordination of an electric vehicle, which can solve the driving frustration caused by the timely four-wheel drive control process and improve the driving experience.

[0049] Reference Figure 1 , Figure 1 The first flow chart of the control method of timely four-wheel drive torque coordination of an electric vehicle provided by an embodiment of the present application includes but is not limited to steps S110 to S140. The electric vehicle is configured such that the front axle is driven by an asynchronous motor and the rear axle is driven by a synchronous motor.

[0050] Step S110, when it is detected that the driving condition satisfies the switching from the two-wheel drive working mode to the four-wheel drive working mode, requesting the electric vehicle to switch from the two-wheel drive working mode to the four-wheel drive working mode, and controlling the working mode of the asynchronous motor to switch from the standby mode to the torque mode;

[0051] Step S120, controlling the asynchronous motor to enter the gear preload stage, and controlling the asynchronous motor to provide the gear preload force of the front axle, and linearly filtering the torque distribution ratio to 0, so as to control the whole vehicle driving demand torque to be borne entirely by the synchronous motor, wherein the filtering parameters are related to the current driving condition;

[0052] Step S130, controlling the asynchronous motor to provide torque according to a pre-calibrated zero-crossing demand torque curve, and adjusting the torque distribution ratio to a first target distribution ratio, so as to control the vehicle driving demand torque to be borne by the asynchronous motor and the synchronous motor in proportion, wherein the first target distribution ratio is associated with the pre-calibrated zero-crossing demand torque curve;

[0053] Step S140, when it is detected that the actual torque of the asynchronous motor is greater than or equal to the first preset torque value, the control is switched from the two-wheel drive working mode to the four-wheel drive working mode.

[0054] In the embodiment of the present application, the operating conditions for activating timely four-wheel drive include the following driving conditions:

[0055] Condition 1: Optimal vehicle efficiency

[0056] Taking into account the efficiency of the front and rear axle motors and the power transmission loss, a single rear-wheel drive economic operation area is preset. In this area, the vehicle runs on single rear-wheel drive and the efficiency of the entire vehicle system is optimal.

[0057] Condition 2: High speed condition

[0058] When the vehicle speed is higher than a preset calibration threshold (such as 120km / h), the vehicle is requested to enter the four-wheel drive working mode.

[0059] Working condition 3: strong energy feedback

[0060] When the total required feedback torque is ≤ |maximum feedback capacity of the rear axle + offest offset value|, the vehicle is requested to enter the four-wheel drive working mode.

[0061] Condition 4: Rear motor driving capability is limited

[0062] When the driver's required torque ≥ |maximum driving capacity of the rear axle + offest offset value|, the vehicle is requested to enter the four-wheel drive working mode.

[0063] Working condition 5: Climbing a steep slope

[0064] If the vehicle speed is <5km / h (TBD) and the slope is > the corresponding slope value in the table of the maximum driving capacity of the rear motor, the vehicle is requested to enter the four-wheel drive working mode.

[0065] Condition 6: Rear wheel slip

[0066] When rear wheel slip is detected, the vehicle is requested to enter four-wheel drive mode to maximize vehicle stability.

[0067] Condition 7: Swing monitoring

[0068] When the steering yaw exceeds the preset target value, the vehicle is requested to enter the four-wheel drive working mode and the vehicle body stability is improved through the four-wheel drive torque distribution.

[0069] Working condition 8: Fault diagnosis

[0070] When the rear motor fails, the vehicle enters the front axle drive mode. When the front motor fails, the vehicle enters the rear axle drive mode.

[0071] Condition 9: Intelligent driving function activated

[0072] When ACC or APA is activated, the vehicle enters four-wheel drive mode.

[0073] Condition 5: Driving mode adaptation

[0074] In driving modes such as ECO / Normal / Sport, the four-wheel drive function is adaptively activated at the right time. For example, the ECO mode is more conducive to single rear-wheel drive, and the preset threshold for activating the four-wheel drive working mode is stricter; the Normal mode is the main mode, and the threshold for activating the vehicle to enter the four-wheel drive working mode is the standard value; the Sport mode is more conducive to the vehicle entering the four-wheel drive working mode and improves the power, and the threshold for activating the vehicle to enter the four-wheel drive working mode is more relaxed.

[0075] In the present application, refer to Figure 2 , Figure 2This is a schematic diagram of the torque coordination process of switching from the two-wheel drive working mode to the four-wheel drive working mode. When the driving conditions meet the conditions for switching from the two-wheel drive working mode to the four-wheel drive working mode, torque coordination control of switching from the two-wheel drive working mode to the four-wheel drive working mode is required. The specific process includes:

[0076] When the driving conditions are met, the two-wheel drive mode is switched to the four-wheel drive mode. Figure 2 The state A position shown in the figure requests the electric vehicle to switch from the two-wheel drive working mode to the four-wheel drive working mode. At the same time, in the state A position, the working mode of the asynchronous motor of the front axle is switched from the standby mode (Standby) to the torque mode (Torque). After the working mode of the front axle asynchronous motor is switched to the torque mode, it cannot immediately respond to the torque required by the vehicle. The asynchronous motor needs to be controlled to enter the gear preload stage (i.e. Figure 2 In the state A~B), the asynchronous motor is controlled to provide the front axle preload, and the torque distribution ratio is linearly filtered to 0, so as to control the whole vehicle driving demand torque to be borne entirely by the synchronous motor, so as to eliminate the driving jitter problem caused by gear clearance. Among them, the filtering parameters are related to the current driving conditions, and the filtering parameters corresponding to different conditions may be different. That is, the torque distribution ratio can be controlled to change slowly to 0 or quickly to 0 under different conditions. If the torque distribution ratio is 0, it means that the required torque of the whole vehicle is borne entirely by the synchronous motor of the rear axle. If the torque distribution ratio is 1, it means that the required torque of the whole vehicle is borne entirely by the asynchronous motor of the front axle. If the torque distribution ratio is 0.6, it means that 60% of the required torque of the whole vehicle is borne by the asynchronous motor of the front axle, and 40% of the required torque of the whole vehicle is borne by the synchronous motor of the rear axle.

[0077] Then it enters state B~C. State B~C is the zero-crossing control stage of the front axle asynchronous motor. In this stage, because the front axle asynchronous motor is near zero torque, the rising slope of the motor torque here is small. At this time, if a larger front axle required torque is requested immediately, the asynchronous motor of the front axle will not respond to zero in time and the torque of the rear axle will drop too fast, which will cause driving frustration and affect driving smoothness. Therefore, in this stage, the asynchronous motor is controlled to provide torque according to the pre-calibrated zero-crossing demand torque curve, and the torque distribution ratio is adjusted to the first target distribution ratio to control the driving demand torque of the whole vehicle to be borne by the asynchronous motor and the synchronous motor in proportion, wherein the first target distribution ratio is associated with the pre-calibrated zero-crossing demand torque curve. That is, by adding a pre-calibrated zero-crossing demand torque curve, the torque of the asynchronous motor is slowly increased. After state C, that is, when the actual torque of the asynchronous motor is greater than or equal to the first preset torque value, that is, after the asynchronous motor is completed, the migration of the torque from two-wheel drive to four-wheel drive is quickly completed. This can solve the acceleration frustration caused by switching from the two-wheel drive working mode to the four-wheel drive working mode and improve the driving experience.

[0078] It should be noted that the pre-calibrated zero-crossing demand torque curve, i.e. Figure 2 The curve segment of the asynchronous motor torque in the B-C stage shown in is a curve of the asynchronous motor zero-crossing demand torque size changing with time. The first target allocation ratio corresponding to the current moment is equal to the ratio of the asynchronous motor zero-crossing demand torque corresponding to the current moment to the vehicle driving demand torque corresponding to the current moment. Specifically, the first target allocation ratio can be calculated by the following formula 1:

[0079]

[0080] Wherein, Rat1 represents the first target distribution ratio, Tq(fx) represents the pre-calibrated zero-crossing demand torque curve, such as a step signal, a ramp signal, etc., and Tq total Indicates the driving torque required for the entire vehicle.

[0081] It can be seen from Formula 1 that since the pre-calibrated zero-crossing demand torque curve Tq(fx) is a curve of the magnitude of the zero-crossing demand torque of the asynchronous motor changing with time, that is, different zero-crossing demand torques correspond to different times. The corresponding vehicle driving demand torque at different times may also be different, so the first target allocation ratio calculated by Formula 1 also changes with time. For details, please refer to Figure 2 The curve segment of the distribution coefficient in the B~C stage.

[0082] It should be noted that the calculation formula for calculating the first target allocation ratio shown in Formula 1 is only applicable to Figure 2 In stages B to C, after the control is switched from the two-wheel drive mode to the four-wheel drive mode, the electric vehicle controls the driving demand torque of the vehicle according to the most efficient distribution ratio, and the asynchronous motor and the synchronous motor are borne proportionally, thereby achieving the optimal efficiency of the vehicle.

[0083] In some embodiments, the pre-calibrated zero-crossing demand torque curve is associated with the driving condition. Different driving conditions correspond to different pre-calibrated zero-crossing demand torque curves. Specifically, the pre-calibrated zero-crossing demand torque curves can be set in advance in different driving conditions during the zero-crossing control phase of the front axle asynchronous motor (i.e. Figure 2 The zero-crossing demand torque curve is calibrated in a way that the torque of the front-axle asynchronous motor can rise slowly and meet the zero-crossing response in time without causing driving frustration, so that the pre-calibrated zero-crossing demand torque curve can make the torque of the asynchronous motor rise slowly, solve the problem of driving frustration caused by the small rising slope of the front-axle torque but the immediate request for a larger front-axle demand torque, and improve the driving experience.

[0084] Reference Figure 3 , Figure 3The second flow chart of the control method of timely four-wheel drive torque coordination of an electric vehicle provided by an embodiment of the present application includes but is not limited to steps S310 to S330. The electric vehicle is configured such that the front axle is driven by an asynchronous motor and the rear axle is driven by a synchronous motor.

[0085] Step S310, when it is detected that the driving condition satisfies the switching from the four-wheel drive working mode to the two-wheel drive working mode, requesting the electric vehicle to switch from the four-wheel drive working mode to the two-wheel drive working mode, and controlling the front axle torque to migrate to the rear axle;

[0086] Step S320, controlling the synchronous motor to provide torque according to a pre-calibrated rear-drive request torque curve, and adjusting the torque distribution ratio to a second target distribution ratio, so as to control the vehicle driving demand torque to be proportionally borne by the asynchronous motor and the synchronous motor, wherein the second target distribution ratio is associated with the pre-calibrated rear-drive request torque curve;

[0087] Step S330, when it is detected that the actual torque of the synchronous motor is greater than or equal to the second preset torque value, the torque distribution ratio is linearly filtered to 0 to control the whole vehicle driving demand torque to be borne entirely by the synchronous motor, wherein the filtering parameters are related to the current driving conditions.

[0088] In the embodiment of the present application, when it is detected that the driving condition meets the switching from the four-wheel drive working mode to the two-wheel drive working mode, the electric vehicle is requested to switch from the four-wheel drive working mode to the two-wheel drive working mode, and the front axle torque needs to be controlled to migrate to the rear axle. Under different working conditions, the front axle torque needs to drop from the current positive torque to 0, or the front axle torque needs to rise from the current negative torque to 0, and the rear axle torque needs to compensate for the front axle exit torque and meet the vehicle demand torque. In either case, there may be a large difference between the slope of a certain section of the torque unloading curve of the front axle (larger) and the slope of the corresponding section of the torque compensation curve of the rear axle (smaller), resulting in the rear axle being unable to respond to the front axle exit torque in time, which will bring a sense of deceleration and frustration. Therefore, when the embodiment of the present application detects that the driving condition meets the switching from the four-wheel drive working mode to the two-wheel drive working mode, the synchronous motor is controlled to provide torque according to the pre-calibrated rear drive request torque curve, and the torque distribution ratio is adjusted to the second target distribution ratio, so as to control the vehicle driving demand torque to be borne by the asynchronous motor and the synchronous motor in proportion, wherein the second target distribution ratio is associated with the pre-calibrated rear drive request torque curve. That is, by adding a pre-calibrated rear-drive request torque curve and distributing torque to the front and rear motors according to the second target distribution ratio, the compensation slope of the torque of the rear axle synchronous motor is made close to the unloading slope of the torque of the front axle asynchronous motor, so that the rear axle can respond to the front axle exit torque in time. Then, when it is detected that the actual torque of the synchronous motor is greater than or equal to the second preset torque value, that is, when it is detected that the rear axle torque leaves the low slope control area, the torque distribution ratio is linearly filtered to 0 (that is, slowly reduced to 0) to control the whole vehicle driving demand torque to be borne entirely by the synchronous motor, and then quickly unload the front axle torque and transfer it to the rear axle. In this way, the deceleration frustration caused by the switch from the four-wheel drive working mode to the two-wheel drive working mode can be solved, and the driving experience can be improved.

[0089] It should be noted that in the embodiment of the present application, when the front axle torque needs to drop from the current positive torque to 0, its drop curve includes multiple curve segments with different slopes. For example, when the torque drops from 100Nm to 50Nm, it drops at a larger slope, that is, it drops quickly from 100Nm to 50Nm, but when the torque drops from 50Nm to 0, it drops at a relatively smaller slope, that is, 50Nm drops slowly to 0. At this time, for the curve segment with a larger drop slope of the front axle torque, there will be a large difference with the corresponding rising slope (smaller) of the torque rising curve segment of the rear axle compensation, resulting in the rear axle being unable to respond to the front axle exit torque in time. Therefore, in the embodiment of the present application, the torque rising curve segment of the rear axle compensation is replaced with a pre-calibrated rear drive request torque curve, and the torque distribution ratio is adjusted to the second target distribution ratio, so that the rear axle synchronous motor can provide torque according to the pre-calibrated rear drive request torque curve, and the remaining driver demand torque (i.e., the vehicle demand torque minus the torque provided by the rear axle) is borne by the front axle asynchronous motor. In this way, the slope of the corresponding front axle torque reduction curve segment with a larger slope can be indirectly reduced, and the downward slope of the front axle torque reduction curve segment after the slope is reduced can be close to the rising slope of the pre-calibrated rear-wheel drive request torque curve segment after replacement, thereby eliminating the sense of frustration caused by the rear axle's inability to respond to the front axle exit torque in time.

[0090] It should also be noted that in the embodiment of the present application, when the front axle torque needs to rise from the current negative torque to 0, its rising curve includes multiple curve segments with different slopes. For example, when the torque rises from -100Nm to -50Nm, it rises at a larger slope, that is, it rises quickly from -100Nm to -50Nm, but when the torque rises from -50Nm to 0, it rises at a relatively smaller slope, that is, it rises slowly from -50Nm to 0. At this time, for the curve segment with a larger rising slope of the front axle torque, there will be a large difference with the corresponding (smaller) falling slope of the torque drop curve segment of the rear axle compensation, resulting in the rear axle being unable to respond to the front axle exit torque in time. Therefore, in the embodiment of the present application, the torque drop curve segment of the rear axle compensation is replaced with a pre-calibrated rear drive request torque curve, and the torque distribution ratio is adjusted to the second target distribution ratio, so that the rear axle synchronous motor can provide torque according to the pre-calibrated rear drive request torque curve, and the remaining driver demand torque (i.e., the vehicle demand torque minus the torque provided by the rear axle) is borne by the front axle asynchronous motor. In this way, the slope of the corresponding front axle torque rising curve segment with a larger slope can be indirectly reduced, and the rising slope of the front axle torque rising curve segment after the slope is reduced can be close to the falling slope of the pre-calibrated rear-wheel drive request torque curve segment after replacement, thereby eliminating the sense of frustration caused by the rear axle's inability to respond to the front axle exit torque in time.

[0091] It should be noted that when the vehicle switches from the four-wheel drive working mode to the two-wheel drive working mode, the preset filter parameters of the torque distribution ratio will be determined by comprehensively considering the current driving conditions of the vehicle and the parameters related to the vehicle body stability. For example, when the four-wheel drive is switched to the two-wheel drive, a large turn is encountered, or the current road surface is identified as a slippery road, or the current vehicle is on a downhill section, etc., considering the stability advantage of the four-wheel drive vehicle, the filter parameters of the torque distribution ratio when the four-wheel drive is switched to the two-wheel drive are limited, even if the torque distribution ratio slowly becomes 0, to avoid the torque from migrating too quickly to the rear axle and causing vehicle stability problems. For other working conditions, the filter slope can be appropriately accelerated, even if the torque distribution ratio quickly becomes 0, so as to quickly complete the switch from four-wheel drive to rear-wheel drive.

[0092] On the contrary, when the vehicle switches from two-wheel drive mode to four-wheel drive mode, if it encounters large turns, slippery roads or downhill conditions, it will compensate or accelerate the filtering parameters of the torque distribution ratio to quickly complete the switch from two-wheel drive to four-wheel drive, thereby improving the stability of the vehicle in the above conditions.

[0093] Reference Figure 4 , Figure 4 This is a schematic diagram of the torque coordination process of switching from the four-wheel drive working mode to the two-wheel drive working mode. Taking the vehicle in braking or coasting energy recovery conditions as an example, it is explained in detail. When the driving conditions meet the conditions for switching from the four-wheel drive working mode to the two-wheel drive working mode, the torque coordination control of the four-wheel drive working mode switching to the two-wheel drive working mode is required. The specific process includes:

[0094] When the driving conditions are met to switch from the four-wheel drive mode to the two-wheel drive mode, the front axle torque needs to be controlled to migrate to the rear axle. Figure 4 The state D position shown in the figure requests the electric vehicle to switch from the four-wheel drive working mode to the two-wheel drive working mode. At this time, the asynchronous motor and the synchronous motor are in the negative torque control request stage. States D to E are the transition stage from the four-wheel drive working mode to the two-wheel drive working mode. In order to complete the switch from the four-wheel drive to the two-wheel drive, the negative torque of the front axle needs to be transferred to the rear axle. Therefore, the front axle torque rises from negative torque to 0 torque, and the rear axle torque needs to compensate for the front axle exit torque. However, due to the large difference in the slope of the rising curve and the falling curve between the front and rear axles, the rear axle cannot respond to the front axle exit torque in time, which will cause a sense of deceleration. Therefore, in this transition stage, the synchronous motor is controlled to provide torque according to the pre-calibrated rear-wheel drive request torque curve, and the torque distribution ratio is adjusted to the second target distribution ratio, so as to control the vehicle driving demand torque to be borne by the asynchronous motor and the synchronous motor in proportion, wherein the second target distribution ratio is associated with the pre-calibrated rear-wheel drive request torque curve. That is, by adding a pre-calibrated rear-wheel drive request torque curve and distributing the torque according to the second target distribution ratio, the decreasing slope of the torque of the rear-axle synchronous motor is made close to the increasing slope of the torque of the front-axle asynchronous motor, so that the rear axle can respond to the front axle exit torque in time.

[0095] Then, in states E to F, when it is detected that the actual torque of the synchronous motor is greater than or equal to the second preset torque value, that is, when it is detected that the rear axle torque leaves the low slope control area, the torque distribution ratio is adjusted to 0 to control the synchronous motor to bear all the required torque of the vehicle driving, so as to quickly unload the front axle torque and transfer it to the rear axle. In this way, the deceleration frustration caused by switching from the four-wheel drive working mode to the two-wheel drive working mode can be solved, and the driving experience can be improved.

[0096] In some embodiments, after the torque distribution ratio is linearly filtered to 0 to control the synchronous motor to bear all the driving torque of the vehicle, when the actual torque of the asynchronous motor is detected to be 0, the working mode of the asynchronous motor is controlled to switch from the torque mode to the standby mode. Figure 4 In state F, when the torque of the front axle is unloaded to 0, the working mode of the front axle asynchronous motor is switched from torque mode to standby mode, completing the switching process from four-wheel drive working mode to two-wheel drive working mode.

[0097] It should be noted that the actual torque of the asynchronous motor is near 0. If it is close to 0 within the tolerance range, the actual torque of the asynchronous motor can be regarded as 0.

[0098] It should be noted that the pre-calibrated rear drive request torque curve, i.e. Figure 4 The curve segment of the synchronous motor torque in the D-E stage shown in is a curve of the synchronous motor rear drive request torque size changing with time. The second target allocation ratio corresponding to the current moment is equal to 1 minus the ratio of the synchronous motor rear drive request torque corresponding to the current moment to the vehicle driving demand torque corresponding to the current moment. Specifically, the second target allocation ratio can be calculated by the following formula 2:

[0099]

[0100] Wherein, Rat2 represents the second target distribution ratio, Tq(rx) represents the pre-calibrated rear drive request torque curve, Tq total Indicates the driving torque required for the entire vehicle.

[0101] It can be seen from Formula 2 that since the pre-calibrated rear-drive request torque curve Tq(rx) is a curve showing the synchronous motor rear-drive request torque changing with time, that is, different rear-drive request torques correspond to different times. The corresponding vehicle driving demand torques at different times may also be different, so the second target allocation ratio calculated by Formula 2 also changes with time. For details, please refer to Figure 4 The curve segment of the distribution coefficient in the D~E stage.

[0102] It should be noted that the calculation formula for calculating the second target allocation ratio shown in Formula 2 is only applicable to Figure 4In the D-E stage, after the control is switched from the four-wheel drive working mode to the two-wheel drive working mode, the electric vehicle adjusts the torque distribution ratio to 0 to control the synchronous motor to bear all the driving torque required by the vehicle.

[0103] In some embodiments, the pre-calibrated rear-wheel drive request torque curve is associated with the driving condition. Different driving conditions correspond to different pre-calibrated rear-wheel drive request torque curves. Specifically, the pre-calibrated rear-wheel drive request torque curve can be pre-calibrated in different driving conditions during the transition phase (i.e., Figure 4 The rear-wheel drive request torque curve is obtained by calibrating the decreasing slope of the torque of the rear-axle synchronous motor in a manner that makes the increasing slope of the torque of the front-axle asynchronous motor close to that of the rear-axle synchronous motor, so that the pre-calibrated rear-wheel drive request torque curve enables the rear axle to respond to the front axle exit torque in a timely manner, thereby solving the problem of driving frustration caused by the large difference between the decreasing slope of the torque of the rear-axle synchronous motor and the increasing slope of the torque of the front-axle asynchronous motor, and improving the driving experience.

[0104] In some embodiments, Figure 4 In the D-E stage shown, the second target allocation ratio floats within a preset range. When the second target allocation ratio is not within the preset range, the pre-calibrated rear drive request torque curve can be corrected based on the preset range. For example, the second target allocation ratio can be set to float between 0.6 and 0.7. When the second target allocation ratio calculated according to the above formula 2 is not within 0.6-0.7, the pre-calibrated rear drive request torque curve can be corrected based on the preset range of 0.6-0.7 to meet the requirements of the rear drive torque curve. Figure 4 In the stages D to E shown, the second target allocation ratio may always float within a preset range.

[0105] Based on the same inventive concept, an embodiment of the present application also provides a computer program product, which includes computer instructions, which are stored in a computer-readable storage medium and are suitable for being read and executed by a processor, so that a computer device with the processor executes a method provided in any of the above embodiments.

[0106] See also Figure 5 , Figure 5 The hardware structure of the computer program product of the embodiment of the present application is illustrated, and the computer program product includes:

[0107] The processor 501 may be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present application;

[0108] The memory 502 can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 502 can store an operating system and other application programs. When the technical solution provided in the embodiment of this specification is implemented by software or firmware, the relevant program code is stored in the memory 502, and the processor 501 calls and executes the shift control method of the electric drive clutch sleeve provided in the embodiment of this application;

[0109] Input / output interface 503, used to implement information input and output;

[0110] Communication interface 504, used to realize communication interaction between the device and other devices, which can be realized by wired mode (such as USB, network cable, etc.) or wireless mode (such as mobile network, WIFI, Bluetooth, etc.);

[0111] A bus 505 that transmits information between the various components of the device (e.g., the processor 501, the memory 502, the input / output interface 503, and the communication interface 504);

[0112] The processor 501 , the memory 502 , the input / output interface 503 and the communication interface 504 are connected to each other in communication within the device via the bus 505 .

[0113] Based on the same inventive concept, the embodiment of the present application further provides a vehicle, referring to Figure 6 , shows a schematic diagram of the structure of a vehicle in an embodiment of the present application, wherein the vehicle includes one or more memories 604, one or more processors 602, and at least one computer program (computer program instruction) stored in the memories 604 and executable on the processors 602, and the processor 602 implements the method described above when executing the computer program.

[0114] Among them, Figure 6In the embodiment of the present invention, a bus architecture (represented by bus 600) is shown, which may include any number of interconnected buses and bridges, and bus 600 links various circuits including one or more processors represented by processor 602 and memory represented by memory 604. Bus 600 may also link various other circuits such as peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. Bus interface 605 provides an interface between bus 600 and receiver 601 and transmitter 603. Receiver 601 and transmitter 603 may be the same element, namely a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 602 is responsible for managing bus 600 and general processing, while memory 604 may be used to store data used by processor 602 when performing operations.

[0115] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on a computer-readable medium or transmitted via a computer-readable medium. Other examples and implementations are within the scope and spirit of the present application and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hard wiring, or a combination of any of these. In addition, each functional unit may be integrated into a processing unit, each unit may exist physically separately, or two or more units may be integrated into one unit.

[0116] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0117] The units described as separate components may or may not be physically separated, and the components of the control device may or may not be physical units, that is, they may be located in one place or distributed in multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0118] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly or all or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk, etc., which can store computer program instructions.

[0119] The above description is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. A control method for timely four-wheel drive torque coordination of an electric vehicle, characterized in that: The electric vehicle is configured such that the front axle is driven by an asynchronous motor and the rear axle is driven by a synchronous motor, and the method comprises: When it is detected that the driving condition satisfies the switching from the two-wheel drive working mode to the four-wheel drive working mode, requesting the electric vehicle to switch from the two-wheel drive working mode to the four-wheel drive working mode, and controlling the working mode of the asynchronous motor to switch from the standby mode to the torque mode; Control the asynchronous motor to enter the gear preload stage, control the asynchronous motor to provide the gear preload force of the front axle, and linearly filter the torque distribution ratio to 0, so as to control the synchronous motor to bear all the required torque of the vehicle driving, wherein the filtering parameters are related to the current driving condition; Controlling the asynchronous motor to provide torque according to a pre-calibrated zero-crossing demand torque curve, and adjusting the torque distribution ratio to a first target distribution ratio, so as to control the vehicle driving demand torque to be borne by the asynchronous motor and the synchronous motor in proportion, wherein the first target distribution ratio is associated with the pre-calibrated zero-crossing demand torque curve; When it is detected that the actual torque of the asynchronous motor is greater than or equal to a first preset torque value, the control is switched from the two-wheel drive working mode to the four-wheel drive working mode.

2. The method according to claim 1, characterized in that The pre-calibrated zero-crossing demand torque curve is a curve showing the change of the zero-crossing demand torque of the asynchronous motor over time. The first target allocation ratio corresponding to the current moment is equal to the ratio of the zero-crossing demand torque of the asynchronous motor corresponding to the current moment to the driving demand torque of the whole vehicle corresponding to the current moment.

3. The method according to claim 1, characterized in that The pre-calibrated zero-crossing demand torque curve is associated with a driving condition. Different driving conditions correspond to different pre-calibrated zero-crossing demand torque curves.

4. The method according to claim 1, characterized in that: The method further comprises: When it is detected that the driving condition satisfies the switching from the four-wheel drive working mode to the two-wheel drive working mode, requesting the electric vehicle to switch from the four-wheel drive working mode to the two-wheel drive working mode, and controlling the front axle torque to migrate to the rear axle; Controlling the synchronous motor to provide torque according to a pre-calibrated rear-drive request torque curve, and adjusting the torque distribution ratio to a second target distribution ratio, so as to control the vehicle driving demand torque to be borne by the asynchronous motor and the synchronous motor in proportion, wherein the second target distribution ratio is associated with the pre-calibrated rear-drive request torque curve; When it is detected that the actual torque of the synchronous motor is greater than or equal to the second preset torque value, the torque distribution ratio is linearly filtered to 0 to control the whole vehicle driving demand torque to be borne entirely by the synchronous motor, wherein the filtering parameters are related to the current driving conditions.

5. The method according to claim 4, characterized in that The pre-calibrated rear-wheel drive request torque curve is a curve showing the change in the synchronous motor rear-wheel drive request torque over time. The second target allocation ratio corresponding to the current moment is equal to 1 minus the ratio of the synchronous motor rear-wheel drive request torque corresponding to the current moment to the vehicle driving demand torque corresponding to the current moment.

6. The method according to claim 5, characterized in that The second target allocation ratio fluctuates within a preset range. When the second target allocation ratio is not within the preset range, the method further includes: The pre-calibrated rear-drive request torque curve is modified based on the preset range.

7. The method according to claim 4, characterized in that After adjusting the torque distribution ratio to 0 so as to control the whole vehicle driving demand torque to be borne entirely by the synchronous motor, the method further includes: When it is detected that the actual torque of the asynchronous motor is 0, the working mode of the asynchronous motor is controlled to switch from the torque mode to the standby mode.

8. The method according to claim 4, characterized in that The pre-calibrated rear-drive request torque curve is associated with a driving condition. Different driving conditions correspond to different pre-calibrated rear-drive request torque curves.

9. A computer program product, characterized in that The computer program product includes computer instructions, which are stored in a computer-readable storage medium and are suitable for being read and executed by a processor, so that a computer device having the processor performs the method according to any one of claims 1 to 8.

10. A vehicle comprising a processor and a memory, characterized in that: The memory stores computer program instructions that can be executed by the processor, and when the processor executes the computer program instructions, the processor implements instructions of any one of the methods according to claims 1 to 8.

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