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

Abstract

The present application discloses a control method, program product and vehicle for timely four-wheel drive torque coordination of an electric vehicle, belonging to the field of vehicle control technology. In this method, the electric vehicle is configured so that the front axle is driven by an asynchronous motor and the rear axle is driven by a synchronous motor. Considering that the torque rising slope of the asynchronous motor is small during the zero-crossing control stage, if a larger front axle demand torque is immediately requested at this time, there will be a sense of acceleration frustration due to the asynchronous motor of the front axle not responding to zero in time and the rear axle torque dropping too fast, which affects the driving smoothness. Therefore, the present application adds a pre-calibrated zero-crossing demand torque curve to slowly increase the torque of the asynchronous motor. 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 process of switching from the two-wheel drive working mode to the four-wheel drive working mode and improve the driving experience.

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 automotive industry and the growing awareness of green environmental protection in modern society, electric vehicles are becoming increasingly popular. Different driving environments and driving requirements may require different vehicle performance and energy management. To adapt to different road conditions and driving requirements, electric vehicles are typically equipped with operating modes such as two-wheel drive and four-wheel drive.

[0003] However, when switching from two-wheel drive mode to four-wheel drive mode, the slope of the torque rise curve of the front axle asynchronous motor is small during the zero-crossing control stage. If a larger front axle torque is requested immediately at this time, the front axle motor will not respond to zero in time and the rear axle torque will drop too quickly, causing acceleration jerk, 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 practice of the present application.

[0006] According to a first aspect of an embodiment of the present application, a method for controlling 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, the method comprising:

[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] Controlling the asynchronous motor to enter the gear preload phase, controlling the asynchronous motor to provide the front axle gear preload force, and linearly filtering the torque distribution ratio to 0, so that the entire vehicle driving torque is entirely borne by the synchronous motor, wherein the filtering parameters are related to the current driving conditions;

[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 shared proportionally by the asynchronous motor and the synchronous motor, 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 in 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 aforementioned 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 aforementioned solution, the method further includes:

[0016] When it is detected that the driving condition satisfies the requirement to switch from the four-wheel drive mode to the two-wheel drive mode, requesting the electric vehicle to switch from the four-wheel drive mode to the two-wheel drive 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-wheel 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 shared proportionally by the asynchronous motor and the synchronous motor, wherein the second target distribution ratio is associated with the pre-calibrated rear-wheel 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 synchronous motor to bear all the required driving torque of the vehicle, 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 aforementioned solution, 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:

[0021] The pre-calibrated rear-wheel drive request torque curve is corrected 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 so as to control the synchronous motor to bear all the required driving torque of the vehicle, 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 aforementioned solution, 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.

[0025] According to a second aspect of an embodiment of the present application, a computer program product is provided, 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 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, an 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 conditions meet the requirement to switch from a two-wheel drive mode to a four-wheel drive mode, the electric vehicle is requested to switch from the two-wheel drive mode to the four-wheel drive mode, and the asynchronous motor's operating mode is controlled to switch from a standby mode to a torque mode. The asynchronous motor is then controlled to enter a gear preload phase, where it provides the front axle gear preload force. The torque split ratio is adjusted to 0, so that the entire vehicle's driving torque demand is entirely borne by the synchronous motor. This eliminates the jerking sensation caused by the asynchronous motor's gearing. Considering that the asynchronous motor has a low torque rise slope during the zero-crossing control phase, immediately requesting a higher front axle torque demand at this time would result in acceleration jerking due to the asynchronous motor's delayed zero-crossing response and a rapid decrease in rear axle torque, affecting driving smoothness. Therefore, this application controls the asynchronous motor to provide torque according to a pre-calibrated zero-crossing torque demand curve and adjusts the torque split ratio to a first target split ratio, so that the entire vehicle's driving torque demand is proportionally borne by the asynchronous motor and the synchronous motor. That is, by adding a pre-calibrated zero-crossing demand torque curve, the torque of the asynchronous motor is slowly increased. 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. This can solve the driving frustration caused by 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 accompanying drawings are incorporated into and constitute a part of the specification, illustrating embodiments consistent with the present application and, together with the specification, explaining the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without inventive effort. In the drawings:

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

[0031] Figure 2 It is a schematic diagram of the torque coordination process when 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 one embodiment of the present application.

[0033] Figure 4It is a schematic diagram of the torque coordination process when 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 structural schematic diagram 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 this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts 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 so as to provide a full understanding of the embodiments of the present application. However, it will be appreciated by those skilled in the art 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, implementations 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 separate entities. That is, these functional entities may be implemented in software, 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 for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[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 to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. 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 front-axle asynchronous motor and a rear-axle synchronous motor in the four-wheel drive configuration to achieve vehicle drive. Through strategic control, timely four-wheel drive function is achieved, 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 in electronic control between the two motors is that synchronous motors cannot be requested to open at high vehicle speeds. Otherwise, the increased motor speed generates a large back EMF, which would flow through the freewheeling diode into the power supply, potentially causing overvoltage and capacitor damage. However, asynchronous motors do not have these concerns. Therefore, by configuring asynchronous front axle and synchronous rear axle motors, timely four-wheel drive is achieved, reducing costs while improving range.

[0046] New energy electric vehicles equipped with front-axle asynchronous motors and rear-axle synchronous motors can achieve timely all-wheel drive through control strategies. The use of an asynchronous motor on the front axle significantly reduces vehicle cost. By optimizing vehicle system efficiency, the asynchronous motor is shut down in inefficient operating areas, with the rear-axle synchronous motor providing all the vehicle's drive torque. The vehicle behaves as a single rear-wheel drive vehicle, with the front asynchronous motor operating in standby mode and speed-dependent. When a high torque request is detected (such as when climbing a hill or applying heavy throttle) or the rear-axle drive capability (both drive and feedback capabilities) does not meet the vehicle's driving requirements, the front asynchronous motor is requested to open (i.e., the motor mode switches from standby to torque mode), and the vehicle switches to all-wheel drive.

[0047] However, when switching from two-wheel drive mode to four-wheel drive mode, the slope of the torque rise curve of the front axle asynchronous motor is small during the zero-crossing control phase. If a larger front axle torque is immediately requested, the front axle motor will not respond to zero in time and the rear axle torque will drop too quickly, causing acceleration jerkiness and affecting driving smoothness. When switching from four-wheel drive mode to two-wheel drive mode, the front axle torque needs to be transferred to the rear axle. The front axle torque will rise from negative torque to 0, or the front axle torque will drop from positive torque to 0, and the rear axle torque needs to compensate for the front axle exit torque and meet the vehicle's required torque. However, there may be a significant difference between the slope of a certain section of the front axle torque unloading curve (larger) and the slope of the corresponding section of the rear axle torque compensation curve (smaller), resulting in the rear axle being unable to respond to the front axle exit torque in time, which will cause deceleration jerkiness.

[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 This is a first flow chart of a method for controlling timely four-wheel drive torque coordination of an electric vehicle provided by an embodiment of the present application, including but 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: Control the asynchronous motor to enter the gear preload phase, control the asynchronous motor to provide the front axle gear preload force, and linearly filter the torque distribution ratio to 0, so that the entire vehicle driving torque is borne entirely by the synchronous motor. The filtering parameters are related to the current driving conditions.

[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 that the vehicle driving demand torque is proportionally shared by the asynchronous motor and the synchronous motor, 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] Working condition 1: optimal vehicle efficiency

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

[0057] Working condition 2: high speed working 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 is ≥ |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 less than 5km / h (TBD) and the slope is greater than the slope value corresponding to 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] Working condition 7: yaw monitoring

[0068] When the steering yaw exceeds the preset target value, the vehicle is requested to enter the four-wheel drive working mode and improve the vehicle stability 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] The four-wheel drive function is adaptively activated in various driving modes, including ECO, Normal, and Sport. For example, ECO mode favors rear-wheel drive alone, and the thresholds for activating the four-wheel drive mode are stricter. Normal mode is the primary mode, and the thresholds for activating the four-wheel drive mode are standard. Sport mode is more conducive to the vehicle's dynamic performance, and the thresholds for activating the four-wheel drive mode are more relaxed.

[0075] In the present application, refer to Figure 2 , Figure 2This is a schematic diagram of the torque coordination process when switching from two-wheel drive mode to four-wheel drive mode. When the driving conditions meet the requirements for switching from two-wheel drive mode to four-wheel drive mode, torque coordination control is required to switch from two-wheel drive mode to four-wheel drive mode. 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 two-wheel drive mode to four-wheel drive mode. At the same time, the working mode of the asynchronous motor controlling the front axle is switched from standby mode to torque mode in state A. After the working mode of the front axle asynchronous motor is switched to torque mode, it cannot immediately respond to the required torque of the vehicle. The asynchronous motor needs to be controlled to enter the gear preload stage (i.e. Figure 2 State A to B in the figure), and control the front axle gear preload provided by the asynchronous motor, linearly filter the torque distribution ratio to 0, so as to control the whole vehicle driving demand torque to be borne entirely by the synchronous motor, thereby eliminating the driving vibration 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 whole vehicle demand torque is borne entirely by the rear axle synchronous motor. If the torque distribution ratio is 1, it means that the whole vehicle demand torque is borne entirely by the front axle asynchronous motor. If the torque distribution ratio is 0.6, it means that 60% of the whole vehicle demand torque is borne by the front axle asynchronous motor, and 40% of the whole vehicle demand torque is borne by the rear axle synchronous motor.

[0077] The vehicle then enters states B-C, which represent the front axle asynchronous motor zero-crossing control phase. During this phase, the front axle asynchronous motor is near zero torque, so the motor torque ramp-up slope is relatively slow. Immediately requesting a higher front axle torque demand would result in a jerk due to the asynchronous motor's delayed zero-crossing response and a rapid drop in rear axle torque, impacting ride smoothness. Therefore, during this phase, the asynchronous motor is controlled to provide torque according to a pre-calibrated zero-crossing torque demand curve, and the torque split ratio is adjusted to a first target split ratio. This ensures that the vehicle's driving torque demand is proportionally distributed between the asynchronous and synchronous motors. The first target split ratio is associated with the pre-calibrated zero-crossing torque demand curve. This means that by adding a pre-calibrated zero-crossing torque demand curve, the asynchronous motor torque ramps up slowly. After state C, when the asynchronous motor's actual torque is greater than or equal to the first preset torque value, i.e., after the asynchronous motor completes zero-crossing, the torque transition from two-wheel drive to four-wheel drive is rapidly completed. This alleviates the acceleration jerk associated with the transition from two-wheel drive to four-wheel drive mode and improves 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 stages B to C shown in FIG. shows the time-varying curve of the asynchronous motor's zero-crossing torque requirement. The first target allocation ratio at the current moment is equal to the ratio of the asynchronous motor's zero-crossing torque requirement to the vehicle's driving torque requirement. Specifically, the first target allocation ratio can be calculated using the following equation 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 vehicle driving demand torque.

[0081] As can be seen from Formula 1, since the pre-calibrated zero-crossing demand torque curve Tq(fx) is a curve showing the change of the zero-crossing demand torque of the asynchronous motor over time, different zero-crossing demand torques correspond to different moments. The corresponding vehicle driving demand torques at different moments may also be different. Therefore, the first target distribution ratio calculated by Formula 1 also changes over time. For details, please refer to Figure 2 The curve segment of the distribution coefficient in stages B to C.

[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 switches from the two-wheel drive working mode to the four-wheel drive working mode, the electric vehicle controls the driving demand torque of the entire vehicle according to the most efficient distribution ratio, and the asynchronous motor and the synchronous motor share the proportion, thereby achieving the optimal efficiency of the entire 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 zero-crossing demand torque curve of the front axle asynchronous motor can be pre-calibrated under different driving conditions. Figure 2 The zero-crossing demand torque curve is obtained by calibrating the torque of the front axle asynchronous motor in a manner that enables the torque to rise slowly and satisfies the zero-crossing response in a timely manner without causing a sense of driving frustration. The pre-calibrated zero-crossing demand torque curve enables the torque of the asynchronous motor to rise slowly, thereby solving the problem of driving frustration caused by the small slope of the front axle torque rise but the immediate request for a larger front axle demand torque, and improving the driving experience.

[0084] Reference Figure 3 , Figure 3This is a second flow chart of a method for controlling timely four-wheel drive torque coordination of an electric vehicle provided by an embodiment of the present application, including but 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 requirement to switch from the four-wheel drive mode to the two-wheel drive mode, the electric vehicle is requested to switch from the four-wheel drive mode to the two-wheel drive mode, and the front axle torque is controlled to transfer to the rear axle;

[0086] Step S320: Controlling the synchronous motor to provide torque according to a pre-calibrated rear-wheel drive request torque curve, and adjusting the torque distribution ratio to a second target distribution ratio, so that the vehicle driving torque demand is proportionally shared by the asynchronous motor and the synchronous motor, wherein the second target distribution ratio is associated with the pre-calibrated rear-wheel drive request torque curve;

[0087] In 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 synchronous motor to bear all the required driving torque of the vehicle, wherein the filtering parameters are related to the current driving conditions.

[0088] In an embodiment of the present application, when it is detected that the driving conditions meet the requirements for switching from a four-wheel drive mode to a two-wheel drive mode, the electric vehicle is requested to switch from the four-wheel drive mode to the two-wheel drive mode, and the front axle torque needs to be controlled to transfer to the rear axle. Under different operating conditions, the front axle torque needs to decrease from the current positive torque to 0, or the front axle torque needs to increase 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's required torque. In either case, there may be a significant difference between the slope of a certain section of the front axle's torque unloading curve (larger) and the slope of the corresponding section of the rear axle's torque compensation curve (smaller), resulting in the rear axle being unable to respond to the front axle exit torque in a timely manner, which may cause a sense of deceleration jerk. Therefore, when it is detected that the driving conditions meet the requirements for switching from the four-wheel drive mode to the two-wheel drive mode, the embodiment of the present application controls the synchronous motor to provide torque according to a pre-calibrated rear-wheel drive request torque curve, and adjusts the torque distribution ratio to a second target distribution ratio, so that the vehicle's required driving torque is proportionally shared by the asynchronous motor and the synchronous motor, 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 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 promptly to the front axle exit torque. 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 has left the low-slope control area, the torque distribution ratio is linearly filtered to 0 (i.e., slowly reduced to 0) to control the entire vehicle's 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 four-wheel drive mode to two-wheel drive 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 decrease from the current positive torque to 0, its decreasing curve includes multiple curve segments with different slopes. For example, when the torque decreases from 100 Nm to 50 Nm, the decrease occurs at a larger slope, meaning it decreases quickly from 100 Nm to 50 Nm. However, when the torque decreases from 50 Nm to 0, the decrease occurs at a relatively smaller slope, meaning it decreases slowly from 50 Nm to 0. In this case, the curve segment with the larger decreasing slope of the front axle torque can differ significantly from the corresponding (smaller) increasing slope of the rear axle compensation torque increasing curve segment, resulting in the rear axle being unable to promptly respond to the front axle exit torque. Therefore, in the embodiment of the present application, the rear axle compensation torque increasing curve segment is replaced with a pre-calibrated rear-drive request torque curve and the torque split ratio is adjusted to a second target split ratio. This allows the rear axle synchronous motor to provide torque according to the pre-calibrated rear-drive request torque curve, while the front axle asynchronous motor provides the remaining driver-demand torque (i.e., the vehicle demand torque minus the rear axle-provided torque). This can indirectly reduce the slope of the corresponding front axle torque reduction curve segment with a larger slope, and make the downward slope of the front axle torque reduction curve segment after the slope is reduced close to the rising slope of the replaced pre-calibrated rear-wheel drive request torque curve segment, 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, the rise from -100 Nm to -50 Nm has a larger slope, meaning it rises quickly from -100 Nm to -50 Nm. However, the rise from -50 Nm to 0 has a relatively smaller slope, meaning it rises slowly from -50 Nm to 0. In this case, the curve segment with the larger rising slope of the front axle torque can differ significantly from the corresponding (smaller) falling slope of the rear axle compensation torque falling curve segment, resulting in the rear axle being unable to respond promptly to the front axle withdrawal torque. Therefore, in the embodiment of the present application, the rear axle compensation torque falling curve segment is replaced with a pre-calibrated rear-drive request torque curve and the torque split ratio is adjusted to a second target split ratio. This allows the rear axle synchronous motor to provide torque according to the pre-calibrated rear-drive request torque curve, while the remaining driver-demand torque (i.e., the vehicle demand torque minus the rear axle-provided torque) is borne by the front axle asynchronous motor. This can indirectly reduce the slope of the corresponding front axle torque rising curve segment with a larger slope, and make the rising slope of the front axle torque rising curve segment after the slope is reduced close to the falling slope of the replaced pre-calibrated rear-wheel drive request torque curve segment, 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 four-wheel drive mode to two-wheel drive mode, the preset filter parameters of the torque distribution ratio will be determined based on a comprehensive consideration of the current vehicle driving conditions and vehicle body stability-related information parameters. For example, when a large turn is encountered during the four-wheel drive to two-wheel drive process, or the current road surface is identified as slippery, or the vehicle is currently on a downhill section, the filter parameters of the torque distribution ratio when the four-wheel drive is switched to two-wheel drive will be limited to account for the stability advantage of the four-wheel drive vehicle. This will cause the torque distribution ratio to slowly become 0, thereby preventing the torque from migrating too quickly to the rear axle and causing vehicle stability issues. For other operating conditions, the filter slope can be appropriately accelerated to quickly complete the switch from four-wheel drive to rear-wheel drive, even if the torque distribution ratio quickly becomes 0.

[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, the filtering parameters of the torque distribution ratio will be compensated or accelerated 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 The diagram below shows the torque coordination process when switching from four-wheel drive to two-wheel drive. This is explained in detail using the vehicle's braking or coasting energy recovery conditions as an example. When the driving conditions meet the requirements for switching from four-wheel drive to two-wheel drive, torque coordination control is required. The specific process includes:

[0094] When the driving conditions are met to switch from four-wheel drive mode to two-wheel drive mode, the front axle torque needs to be controlled to migrate to the rear axle. Figure 4 State D, shown in Figure 1, indicates a positional request for the electric vehicle to switch from four-wheel drive to two-wheel drive mode. During this phase, the asynchronous motor and synchronous motor are in the negative torque control request phase. States D to E represent the transition phase from four-wheel drive to two-wheel drive mode. To complete the switch, the front axle's negative torque must be transferred to the rear axle. Therefore, the front axle torque increases from negative to zero, while the rear axle torque compensates for the front axle's exit torque. However, due to the significant difference in the slopes of the rising and falling curves between the front and rear axles, the rear axle cannot promptly respond to the front axle's exit torque, resulting in a jerky deceleration. Therefore, during this transition phase, the synchronous motor is controlled to provide torque according to a pre-calibrated rear-wheel drive request torque curve, and the torque split ratio is adjusted to a second target split ratio, ensuring that the vehicle's driving torque is proportionally distributed between the asynchronous motor and the synchronous motor. The second target split 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 a timely manner.

[0095] Then, in states E-F, when the actual torque of the synchronous motor is detected to be greater than or equal to the second preset torque value, that is, when the rear axle torque is detected to have left the low-slope control zone, the torque split ratio is adjusted to 0, so that the synchronous motor bears all the required driving torque, quickly unloading the front axle torque and transferring it to the rear axle. This can eliminate the deceleration jerks caused by switching from four-wheel drive to two-wheel drive mode and improve the driving experience.

[0096] In some embodiments, after the torque distribution ratio is linearly filtered to 0 to control the synchronous motor to bear all the required torque of the vehicle driving, 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 front axle torque 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, it can be regarded as the actual torque of the asynchronous motor is 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 during phases D to E shown in FIGURE 2 shows the curve of the synchronous motor rear-wheel drive torque request over time. The second target allocation ratio at the current moment is equal to 1 minus the ratio of the synchronous motor rear-wheel drive torque request at the current moment to the vehicle's required driving torque at the current moment. Specifically, the second target allocation ratio can be calculated using the following equation 2:

[0099]

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

[0101] As can be seen from Formula 2, since the pre-calibrated rear-wheel drive request torque curve Tq(rx) is a curve showing the synchronous motor rear-wheel drive request torque changing with time, that is, different rear-wheel drive request torques are corresponding to different times. The corresponding vehicle driving demand torques at different times may also be different. Therefore, the second target distribution 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 stages, after the control switches 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 requirements of the vehicle.

[0103] In some embodiments, the pre-calibrated rear-wheel drive request torque curve is associated with the driving conditions. Different driving conditions correspond to different pre-calibrated rear-wheel drive request torque curves. Specifically, the pre-calibrated rear-wheel drive request torque curves can be pre-calibrated in different driving conditions during the transition period from the four-wheel drive mode to the two-wheel drive mode (i.e., Figure 4 The rear-wheel drive request torque curve is obtained by calibrating the torque drop rate of the rear-axle synchronous motor in a manner that makes the torque drop rate of the front-axle asynchronous motor close to the torque drop rate of the front-axle asynchronous motor, so that the rear-axle request torque curve can be used to enable 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 torque drop rate of the rear-axle synchronous motor and the torque drop rate of the front-axle asynchronous motor, and improving the driving experience.

[0104] In some embodiments, Figure 4 In the D-E phase shown, the second target distribution ratio fluctuates within a preset range. When the second target distribution 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 distribution ratio can be set to fluctuate between 0.6 and 0.7. When the second target distribution ratio calculated according to the above formula 2 is not within the range of 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 illustrated stages D to E, the second target allocation ratio may always fluctuate 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 the 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. The computer program product includes:

[0107] The processor 501 may be implemented as a general-purpose CPU (Central Processing Unit), a microprocessor, an 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 solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program codes are stored in the memory 502 and are called by the processor 501 to execute the shift control method for the electrically driven clutch sleeve provided in the embodiments of this application.

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

[0110] Communication interface 504, used to implement communication interaction between this device and other devices, which can be achieved through wired means (such as USB, network cable, etc.) or wireless means (such as mobile network, WiFi, Bluetooth, etc.);

[0111] Bus 505 , which transmits information between various components of the device (e.g., processor 501 , memory 502 , input / output interface 503 , and 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 a 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 structural diagram 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 memory 604 and executable on the processor 602, and when the processor 602 executes the computer program, the method described above is implemented.

[0114] Among them, Figure 6In the embodiment of the present invention, a bus architecture (represented by bus 600) is shown. Bus 600 may include any number of interconnected buses and bridges, and bus 600 links together various circuits including one or more processors represented by processor 602 and memory represented by memory 604. Bus 600 may also link together various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further 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 component, namely a transceiver, which provides 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 or transmitted via a computer-readable medium. Other examples and implementations are within the scope and spirit of this 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, hardwiring, or a combination of any of these. Furthermore, the functional units may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single 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 exemplary. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods, such as 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 separate, 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 across 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 is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server or a network device, etc.) to execute 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, magnetic disk or optical disk, etc. Various media that can store computer program instructions.

[0119] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for controlling 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 includes: 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; Controlling the asynchronous motor to enter the gear preload phase, controlling the asynchronous motor to provide the front axle gear preload force, and linearly filtering the torque distribution ratio to 0, so that the entire vehicle driving torque is entirely borne by the synchronous motor, wherein the filtering parameters are related to the current driving conditions; 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 shared proportionally by the asynchronous motor and the synchronous motor, 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 in the magnitude 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, wherein The method further comprises: When it is detected that the driving condition satisfies the requirement to switch from the four-wheel drive mode to the two-wheel drive mode, requesting the electric vehicle to switch from the four-wheel drive mode to the two-wheel drive 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-wheel 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 shared proportionally by the asynchronous motor and the synchronous motor, wherein the second target distribution ratio is associated with the pre-calibrated rear-wheel 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 synchronous motor to bear all the required driving torque of the vehicle, 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 magnitude of the synchronous motor rear-wheel drive request torque over time. The second target distribution 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-wheel drive request torque curve is corrected 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 synchronous motor to bear all the required driving torque of the entire vehicle, 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-wheel drive request torque curve is associated with a driving condition. Different driving conditions correspond to different pre-calibrated rear-wheel drive request torque curves.

9. A computer program product, characterized in that The computer program product includes computer instructions stored in a computer-readable storage medium and adapted to be read and executed by a processor, so as to enable a computer device having the processor to perform 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 the method according to any one of claims 1 to 8.

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