Vehicle powertrain control methods, devices and electric vehicles

Abstract

This invention discloses a vehicle powertrain control method, device, and electric vehicle. The method includes: acquiring the vehicle's driving mode and operating condition parameters; acquiring preset drive mode switching conditions, which are differentiated based on different driving modes; determining a drive mode switching strategy based on the driving mode, operating condition parameters, and preset drive mode switching conditions; and executing the drive mode switching strategy: first, controlling the front axle motor's speed before engagement based on PI control, and then controlling the front axle connection device based on the speed control completion rate, thereby switching the vehicle to four-wheel drive mode; or second, controlling the front axle connection device to disconnect based on torque distribution, and after disconnection, controlling the front axle motor's speed after disconnection based on PI control, thereby switching the vehicle to two-wheel drive mode. This invention improves vehicle economy and power performance by setting multiple switching conditions and combining them with vehicle operating conditions to achieve drive mode switching control.

Description

Technical Field

[0001] This invention relates to the field of vehicle drive control technology, and in particular to a vehicle power system control method, device, and electric vehicle. Background Technology

[0002] Electric four-wheel drive is a drive system that transmits power to the wheels via front and rear motors. A vehicle's electric four-wheel drive system includes electric motors, a gearbox, a controller, and a transmission system. The driver can adjust the output power of the electric motors as needed, and the controller controls the gearbox's gear ratios to deliver power to all four wheels, achieving four-wheel drive for the vehicle.

[0003] In existing technologies, vehicle four-wheel drive control methods typically control the clutch to disengage or engage based on the required torque, and distribute the torque to each motor. Existing technologies have the following problems: the drive control strategy does not fully consider the impact of vehicle conditions on drive mode switching, affecting vehicle driving economy; it does not provide a clutch disengagement / engagement control strategy; the switching conditions between two-wheel drive and four-wheel drive modes are too simplistic, failing to balance vehicle economy and power, thus impacting the driving experience. Summary of the Invention

[0004] This invention provides a vehicle powertrain control method, device, and electric vehicle to solve the problem that existing drive control strategies have only single switching conditions and do not provide a clutch disengagement / engagement strategy, which makes it impossible to balance vehicle economy and power performance. This invention can simultaneously improve vehicle economy and power performance.

[0005] According to one aspect of the present invention, a vehicle powertrain control method is provided, wherein the vehicle operates in two-wheel drive mode or four-wheel drive mode, the powertrain including a front motor, a front axle connection device, and a rear motor, the control method including: acquiring the vehicle's driving mode and operating condition parameters, the driving mode including an economy mode, a comfort mode, and a sport mode; acquiring preset drive mode switching conditions, the preset drive mode switching conditions being differentiated based on different driving modes; determining a drive mode switching strategy based on the driving mode, the operating condition parameters, and the preset drive mode switching conditions; and executing the drive mode switching strategy; wherein executing the drive mode switching strategy includes: performing pre-engagement speed control on the front motor based on PI control, and performing engagement control on the front axle connection device based on the speed control completion degree, thereby switching the vehicle from two-wheel drive mode to four-wheel drive mode; or, performing disengagement control on the front axle connection device based on torque distribution, and after the front axle connection device is disengaged, performing post-disengagement speed control on the front motor based on PI control, thereby switching the vehicle from four-wheel drive mode to two-wheel drive mode.

[0006] Optionally, when the driving mode is the economy mode, the preset driving mode switching conditions include at least one of the following: the vehicle stability system is connected; the road adhesion coefficient is less than the first preset adhesion coefficient; the battery allowable power is less than the first preset low power threshold; the battery allowable power is greater than the first preset low power threshold, and the throttle opening is greater than the preset throttle opening threshold.

[0007] Optionally, when the driving mode is comfort mode, the preset drive mode switching conditions include at least one of the following: the vehicle stability system is engaged; the road adhesion coefficient is less than the second preset adhesion coefficient; the battery allowable power is less than the second preset low power threshold; the current vehicle speed is greater than the preset vehicle speed threshold; the battery allowable power is greater than the second preset low power threshold, and the required torque is greater than the current maximum available output torque of the rear motor.

[0008] Optionally, the front motor is subjected to pre-engagement speed control based on PI control, including: obtaining the output speed of the front axle connecting device according to the current vehicle speed; determining the pre-engagement speed according to the vehicle speed and vehicle acceleration; determining the first target speed of the front motor according to the output speed and the pre-engagement speed; and performing PI control on the front motor according to the first target speed.

[0009] Optionally, the engagement control of the front axle connection device is performed based on the speed control completion degree, including: calculating the speed difference based on the output speed and the actual speed of the front motor; and determining whether to output an engagement control signal based on the pre-applied engagement speed, the speed difference, and the duration of the speed difference.

[0010] Optionally, disconnecting the front axle connection device based on torque distribution includes: acquiring the output torque of the front motor and distributing the output torque of the front motor to the rear motor; determining whether to output a disconnection control signal based on the output torque of the front motor and a preset disconnection torque; and controlling the front motor to output an oscillating torque based on the current vehicle speed before the front axle connection device is completely disconnected.

[0011] Optionally, after the front axle connection device is disconnected, the front motor is subjected to post-disconnection speed control based on PI control, including: taking zero speed as the second target speed of the front motor; and performing PI control on the front motor according to the second target speed.

[0012] Optionally, obtaining the driving mode and operating condition parameters of the vehicle includes: determining the driving mode based on any one or more combinations of the output speed of the front axle connection device, the current vehicle speed, or the required torque; and / or, determining the driving mode based on a driving mode flag.

[0013] According to another aspect of the present invention, a vehicle powertrain control device is provided, wherein the vehicle operates in two-wheel drive mode or four-wheel drive mode, the powertrain including a front motor, a front axle connection device, and a rear motor, for executing the above-described vehicle powertrain control method, the control device including: a parameter acquisition module for acquiring the driving mode and operating condition parameters of the vehicle, the driving mode including economy mode, comfort mode, and sport mode; a switching condition acquisition module for acquiring preset driving mode switching conditions; and a decision module for determining a driving mode switching strategy based on the driving mode, the operating condition parameters, and the preset driving mode switching conditions; wherein the driving mode switching strategy includes: performing pre-engagement speed control on the front motor based on PI control, performing engagement control on the front axle connection device based on the speed control completion degree, thereby switching the vehicle from two-wheel drive mode to four-wheel drive mode; and performing disengagement control on the front axle connection device based on torque distribution, and after the front axle connection device is disengaged, performing post-disengagement speed control on the front motor based on PI control, thereby switching the vehicle from four-wheel drive mode to two-wheel drive mode.

[0014] According to another aspect of the present invention, an electric vehicle is provided, comprising: the aforementioned vehicle power system control device.

[0015] The technical solution of this invention involves acquiring the vehicle's driving mode and operating condition parameters; acquiring preset drive mode switching conditions, which are differentiated based on different driving modes; determining a drive mode switching strategy based on the driving mode, operating condition parameters, and preset drive mode switching conditions; the drive mode switching strategy includes: controlling the front motor's speed before engagement based on PI control, controlling the front axle connection device based on the speed control completion rate, thereby switching the vehicle from two-wheel drive mode to four-wheel drive mode; and controlling the front axle connection device to disconnect based on torque distribution, and controlling the front motor's speed after disconnection based on PI control, thereby switching the vehicle from four-wheel drive mode to two-wheel drive mode. By setting multiple mode switching conditions and matching different drive modes with vehicle operating conditions, the system controls the disengagement / engagement of the front axle connection device, dynamically sets and matches the working states of the front and rear motors, and realizes the switching control of different drive modes. This solves the problem that existing drive control strategies have only single switching conditions and do not provide a clutch disengagement / engagement control strategy, which leads to the inability to balance vehicle economy and power. It enables the rapid disengagement or engagement of the connection device, avoiding abnormalities such as long mode switching time or failure to disengage, and significantly improving vehicle economy while ensuring sufficient power.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a vehicle powertrain control method provided in the first embodiment of the present invention.

[0019] Figure 2 A flowchart of another vehicle powertrain control method provided in the first embodiment of the present invention.

[0020] Figure 3 A flowchart of another vehicle powertrain control method provided in the first embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of a vehicle power system control device provided in the second embodiment of the present invention. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] Figure 1 The flowchart below shows a vehicle powertrain control method according to the first embodiment of the present invention. This embodiment is applicable to the application scenario of driving mode switching of four-wheel drive pure electric vehicles. The method can be executed by a vehicle powertrain control device, which can be implemented in hardware and / or software. The vehicle powertrain control can be configured in the vehicle controller.

[0025] In embodiments of the present invention, the vehicle can operate in either two-wheel drive or four-wheel drive mode. The vehicle powertrain includes a front-mounted motor, a front axle connection device, and a rear-mounted motor. The front axle connection device is located between the front-mounted motor and the front-wheel drive axle. In four-wheel drive mode, the front axle connection device is engaged, and the output torque of the front-mounted motor is transmitted to the front-wheel drive axle to actively drive the front wheels. In two-wheel drive mode, the front axle connection device is disengaged, the output torque of the front-mounted motor cannot be transmitted to the front-wheel drive axle, and the front wheels are in a passive driving state.

[0026] like Figure 1 As shown, the vehicle powertrain control method includes the following steps:

[0027] S1: Obtain the vehicle's driving mode and operating condition parameters. Driving modes include Eco, Comfort, and Sport modes.

[0028] In Eco mode, the vehicle generally operates in two-wheel drive. In Comfort mode, the vehicle generally operates in two-wheel drive. In Sport mode, the vehicle always operates in four-wheel drive when the operating parameters are normal.

[0029] In one embodiment, the operating condition parameters include, but are not limited to: vehicle speed, front motor speed, front motor output torque, rear motor output torque, rear motor speed, connection status of the front axle connection device, road adhesion coefficient, battery allowable power, vehicle required torque, throttle opening, and other parameters related to vehicle operating conditions.

[0030] In one embodiment, obtaining the vehicle's driving mode and operating parameters includes: determining the driving mode based on any one or more combinations of the output speed of the front axle connecting device, the current vehicle speed, or the required torque. Specifically, the vehicle's operating parameters can be collected by sensors or other sampling units, or the operating parameters can be obtained by analyzing the sampled data based on the vehicle controller. For example, the output speed of the front axle connecting device can be collected by a speed sensor, the current vehicle speed can be collected by a vehicle speed sensor, and the required torque can be obtained by a torque sensor or the vehicle controller. Pre-set correspondences between different driving modes and vehicle speed, front and rear motor speeds, and required torque can be pre-defined. After obtaining the operating parameters, the operating parameters at the sampling time are compared with the parameters in the pre-set correspondences to determine the current vehicle's driving mode.

[0031] In other embodiments, the driving mode can be determined based on a driving mode flag. For example, the flag corresponding to the economy mode can be set to 001, the flag corresponding to the comfort mode to 010, and the flag corresponding to the sport mode to 011. By reading the driving mode flag in the vehicle controller, the driving mode at the current sampling time can be obtained.

[0032] S2: Obtain preset driving mode switching conditions, which are set differently based on different driving modes.

[0033] The preset drive mode switching conditions include: when the driving mode is economy mode, the condition of switching from two-wheel drive to four-wheel drive is used as the first switching condition; when the driving mode is comfort mode, the condition of switching from two-wheel drive to four-wheel drive is used as the second switching condition.

[0034] In one embodiment, the first switching condition includes, but is not limited to, at least one of the following: the vehicle stability system is connected; the road adhesion coefficient is less than a first preset adhesion coefficient; the battery allowable power is less than a first preset low power threshold; the battery allowable power is greater than the first preset low power threshold, and the throttle opening is greater than a preset throttle opening threshold.

[0035] In one embodiment, the second switching condition includes, but is not limited to, at least one of the following: the vehicle stability system is connected; the road adhesion coefficient is less than the second preset adhesion coefficient; the battery allowable power is less than the second preset low power threshold; the current vehicle speed is greater than the preset vehicle speed threshold; the battery allowable power is greater than the second preset low power threshold, and the required torque is greater than the current maximum available output torque of the rear motor.

[0036] Among them, the preset adhesion coefficient, preset low power threshold, and preset throttle opening threshold can be established based on the vehicle's operating condition data under different driving modes. The maximum output torque of the rear motor varies with the speed.

[0037] It should be noted that,

[0038] S3: Determine the drive mode switching strategy based on the driving mode, operating condition parameters, and preset drive mode switching conditions.

[0039] The drive mode switching strategy includes, but is not limited to: switching from two-wheel drive mode to four-wheel drive mode, or switching from four-wheel drive mode to two-wheel drive mode.

[0040] S4: Execute the driver mode switching strategy.

[0041] When the drive mode switching strategy is to switch from two-wheel drive mode to four-wheel drive mode, step S410 is executed; when the drive mode switching strategy is to switch from four-wheel drive mode to two-wheel drive mode, step S420 is executed.

[0042] S410: Based on PI control, the front motor is engaged and its speed is controlled. Based on the speed control completion, the front axle connection device is engaged and controlled, so that the vehicle switches from two-wheel drive mode to four-wheel drive mode.

[0043] S420: Based on torque distribution, the front axle connection device is disconnected. After the front axle connection device is disconnected, the speed of the front motor is controlled based on PI control to switch the vehicle from four-wheel drive mode to two-wheel drive mode.

[0044] Specifically, during vehicle operation, the driving mode and operating condition parameters are acquired in real time. When the vehicle is in Eco mode and the drive mode is two-wheel drive, if any of the operating condition parameters meet any of the first switching conditions, the drive mode switching strategy is to switch from two-wheel drive to four-wheel drive. When the vehicle is in Eco mode and the drive mode is four-wheel drive, if the operating condition parameters no longer meet the first switching condition, the drive mode switching strategy is to switch from four-wheel drive to two-wheel drive. When the vehicle is in Comfort mode and the drive mode is two-wheel drive, if any of the operating condition parameters meet any of the second switching conditions, the drive mode switching strategy is to switch from two-wheel drive to four-wheel drive. When the vehicle is in Comfort mode and the drive mode is four-wheel drive, if the operating condition parameters no longer meet the second switching condition, the drive mode switching strategy is to switch from four-wheel drive to two-wheel drive. When the vehicle is in Sport mode, the vehicle always operates in four-wheel drive mode.

[0045] When switching from two-wheel drive to four-wheel drive, the system first uses PI control to control the speed of the front motor before engagement. After speed control, it then controls the engagement of the front axle coupling device to switch the vehicle to four-wheel drive. Conversely, when switching from four-wheel drive to two-wheel drive, the system first uses torque distribution to disengage the front axle coupling device. After disengagement, it then uses PI control to disengage the front motor before speed control to switch the vehicle to two-wheel drive. By setting multiple mode switching conditions and matching different drive modes to the vehicle's operating conditions, the system controls the disengagement / engagement of the front axle coupling device, dynamically setting and matching the operating states of the front and rear motors. This achieves switching control for different drive modes, solving the problem of existing drive control strategies having only single switching conditions and lacking clutch disengagement / engagement control, which prevents a balance between vehicle economy and power. It enables rapid disengagement or engagement of the coupling device, avoiding abnormalities such as long mode switching times or failure to disengage, significantly improving vehicle economy while ensuring sufficient power.

[0046] Optionally, Figure 2 A flowchart of another vehicle powertrain control method provided in the first embodiment of the present invention is shown. Figure 1 Based on this, an exemplary implementation of a specific method for controlling the process of switching from two-wheel drive mode to four-wheel drive mode is shown.

[0047] like Figure 2 As shown, the front motor speed control based on PI control includes:

[0048] S411: Obtain the output speed of the front axle connection device based on the current vehicle speed.

[0049] S412: Determine the pre-engagement speed based on vehicle speed and vehicle acceleration.

[0050] The pre-combining speed can be any value that is greater than or equal to the minimum pre-combining speed and less than or equal to the maximum pre-combining speed.

[0051] S413: Determine the first target speed of the front motor based on the output speed and the pre-applied engagement speed.

[0052] S414: Perform PI control on the front motor based on the first target speed.

[0053] In an embodiment of the present invention, PI control can be used to achieve speed control of the front motor.

[0054] like Figure 2 As shown, the engagement control of the front axle connection device is performed based on the speed control completion rate, including:

[0055] S415: Calculate the speed difference based on the output speed and the actual speed of the front motor.

[0056] S416: Determine whether to output a engagement control signal based on the pre-applied engagement speed, speed difference, and speed difference duration.

[0057] In an embodiment of the present invention, when the speed difference between the output speed of the front connecting device and the speed of the front motor is greater than the minimum pre-applied engagement speed difference but less than the maximum pre-applied engagement speed difference, and the duration is greater than the preset speed difference duration, an engagement control signal is output to control the front connecting device to initiate engagement. After the front connecting device engages, the vehicle is in four-wheel drive mode, at which time the vehicle is driven by both the front motor and the rear motor.

[0058] Specifically, if the vehicle's initial drive mode is two-wheel drive, the front axle connection is disconnected, and the vehicle is driven only by the rear motor. Taking the vehicle running in economy mode and the drive mode as two-wheel drive as an example, when any of the operating parameters meet any of the first switching conditions, the drive mode switching strategy from two-wheel drive to four-wheel drive is executed. First, the vehicle is controlled to enter a speed control state. The first target speed is calculated based on the sum of the output speed of the front axle connection calculated from the current vehicle speed and the pre-applied engagement speed. PI control is then applied based on the speed difference between the first target speed and the front motor to shorten the engagement time of the front connection and avoid excessive engagement time. During the engagement control of the front connection, stable engagement of the mechanical connection is achieved by setting judgment conditions such as the pre-applied engagement speed, speed difference, and speed difference duration, avoiding vibration or large impact during engagement.

[0059] Optionally, Figure 3 A flowchart of another vehicle powertrain control method provided in the first embodiment of the present invention is shown. Figure 1 Based on this, an exemplary implementation of a specific method for controlling the process of switching from four-wheel drive mode to two-wheel drive mode is shown.

[0060] like Figure 3 As shown, the disconnection control of the front axle connection device based on torque distribution includes:

[0061] S421: Obtain the output torque of the front motor and distribute the output torque of the front motor to the rear motor.

[0062] S422: Determine whether to output a disconnection control signal based on the output torque of the front motor and the preset disconnection torque.

[0063] In an embodiment of the present invention, when the output torque of the front motor is less than the preset disconnection torque, the front connection device begins to disconnect.

[0064] In one embodiment, before the front axle connection is completely disconnected, the front motor outputs oscillating torque based on the current vehicle speed. By outputting oscillating torque from the front motor, torque fluctuations are avoided while ensuring reliable disconnection of the front connection, preventing issues such as reduced vehicle power and fuel economy caused by the front connection failing to disconnect.

[0065] like Figure 3 As shown, after the front axle connection is disconnected, the speed control of the front motor is performed based on PI control, including:

[0066] S423: After the front axle connection device is disconnected, zero speed is taken as the second target speed of the front motor, and PI control is performed on the front motor according to the second target speed.

[0067] In an embodiment of the present invention, PI control is performed based on the speed difference between the second target speed and the actual speed of the front motor to ensure that the front motor is shut down in real time after disconnection.

[0068] Specifically, if the vehicle's initial drive mode is four-wheel drive, the front axle connection is engaged, and the vehicle is driven by the front and rear motors. Taking the vehicle as an example, operating in economy mode with four-wheel drive, if the operating parameters do not meet all the conditions in the first switching condition, a drive mode switching strategy to switch from four-wheel drive to two-wheel drive is executed. First, the front connection is controlled to enter the disconnected state, distributing the torque of the front motor to the rear motor. When the output torque of the front motor is less than the preset disconnection torque, the front connection begins to disconnect. If the front connection fails to disconnect successfully, the front motor outputs oscillating torque based on the current vehicle speed. By outputting oscillating torque from the front motor, torque fluctuations are avoided while ensuring reliable disconnection of the front connection. After the front connection is successfully disconnected, the vehicle enters the speed control phase. Zero speed is used as the second target speed for the front motor. PI control is performed based on the speed difference between the second target speed and the actual speed of the front motor to ensure real-time shutdown of the front motor after disconnection, achieving dynamic matching of motor states.

[0069] Based on the same inventive concept, embodiments of the present invention also provide a vehicle powertrain control device, which can execute the vehicle powertrain control method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of executing the method.

[0070] Figure 4 This is a schematic diagram of a vehicle power system control device provided in the second embodiment of the present invention.

[0071] like Figure 4 As shown, the control device includes: a parameter acquisition module 100, a switching condition acquisition module 200, and a decision module 300.

[0072] The parameter acquisition module 100 is used to acquire the vehicle's driving mode and operating condition parameters. The driving modes include economy mode, comfort mode and sport mode.

[0073] The switching condition acquisition module 200 is used to acquire preset driving mode switching conditions, which are set differently based on different driving modes.

[0074] The decision module 300 is used to determine the drive mode switching strategy based on the driving mode, operating condition parameters and preset drive mode switching conditions.

[0075] The drive mode switching strategies include: using PI control to control the front motor's speed before engagement, and using PI control to control the front axle connection device to engage based on the speed control completion, thereby switching the vehicle from two-wheel drive mode to four-wheel drive mode; or, using torque distribution to control the front axle connection device to disconnect, and using PI control to control the front motor's speed after disconnection, thereby switching the vehicle from four-wheel drive mode to two-wheel drive mode.

[0076] In one embodiment, when the driving mode is economy mode, the preset driving mode switching conditions include at least one of the following: the vehicle stability system is connected; the road adhesion coefficient is less than a first preset adhesion coefficient; the battery allowable power is less than a first preset low power threshold; the battery allowable power is greater than the first preset low power threshold, and the throttle opening is greater than a preset throttle opening threshold.

[0077] In one embodiment, when the driving mode is comfort mode, the preset drive mode switching conditions include at least one of the following: the vehicle stability system is connected; the road adhesion coefficient is less than the second preset adhesion coefficient; the battery allowable power is less than the second preset low power threshold; the current vehicle speed is greater than the preset vehicle speed threshold; the battery allowable power is greater than the second preset low power threshold, and the required torque is greater than the current maximum available output torque of the rear motor.

[0078] In one embodiment, the front motor is controlled by PI control before engagement, including: obtaining the output speed of the front axle connecting device based on the current vehicle speed; determining the pre-engagement speed based on the vehicle speed and vehicle acceleration; determining a first target speed of the front motor based on the output speed and the pre-engagement speed; and performing PI control on the front motor based on the first target speed.

[0079] In one embodiment, the engagement control of the front axle connection device is performed based on the speed control completion degree, including: calculating the speed difference based on the output speed and the actual speed of the front motor; and determining whether to output an engagement control signal based on the pre-applied engagement speed, the speed difference, and the duration of the speed difference.

[0080] In one embodiment, disconnection control of the front axle connection device based on torque distribution includes: acquiring the output torque of the front motor and distributing the output torque of the front motor to the rear motor; determining whether to output a disconnection control signal based on the output torque of the front motor and a preset disconnection torque; and controlling the output oscillating torque of the front motor based on the current vehicle speed before the front axle connection device is completely disconnected.

[0081] In one embodiment, after the front axle connection device is disconnected, the front motor speed is controlled based on PI control, including: taking zero speed as the second target speed of the front motor; and performing PI control on the front motor according to the second target speed.

[0082] In one embodiment, the parameter acquisition module 100 is used to determine the driving mode based on any one or more combinations of the output speed of the front axle connection device, the current vehicle speed, or the required torque; and / or, to determine the driving mode based on the driving mode flag.

[0083] Based on the same inventive concept, embodiments of the present invention also provide an electric vehicle, including: the vehicle power system control device provided in any of the above embodiments.

[0084] The vehicle powertrain control device includes a parameter acquisition module, a switching condition acquisition module, and a decision module. The parameter acquisition module acquires the vehicle's driving mode and operating condition parameters. The switching condition acquisition module acquires preset drive mode switching conditions, which are differentiated based on different driving modes. The decision module determines the drive mode switching strategy based on the driving mode, operating condition parameters, and preset drive mode switching conditions. When the drive mode switching strategy is from two-wheel drive to four-wheel drive, PI control is used to control the front motor's engagement speed before engagement, and the front axle connection device is controlled based on the speed control completion rate, thus switching the vehicle from two-wheel drive to four-wheel drive. When the drive mode switching strategy is from four-wheel drive to two-wheel drive, torque distribution control is used to disconnect the front axle connection device. After the front axle connection device is disconnected, PI control is used to control the front motor's engagement speed after disconnection, thus switching the vehicle from four-wheel drive to two-wheel drive.

[0085] The technical solution of this invention sets multiple mode switching conditions, matches different drive modes with vehicle operating conditions, controls the front axle connection device to disconnect / engage, and dynamically sets and matches the working states of the front motor and the rear motor to achieve switching control of different drive modes. This solves the problem that existing drive control strategies have single switching conditions and do not provide a clutch disconnect / engagement control strategy, which leads to the inability to balance vehicle economy and power. It enables rapid disconnection or engagement of the connection device, avoids abnormalities such as long mode switching time or inability to disconnect, and significantly improves vehicle economy while ensuring sufficient power.

[0086] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0087] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A vehicle powertrain control method, wherein the vehicle operates in two-wheel drive mode or four-wheel drive mode, the powertrain comprising a front-mounted motor, a front axle connection device, and a rear-mounted motor, characterized in that, The control method includes: The driving mode and operating condition parameters of the vehicle are obtained, including the driving mode, comfort mode and sport mode; Obtain preset driving mode switching conditions, which are set differently based on different driving modes; The drive mode switching strategy is determined based on the driving mode, the operating condition parameters, and the preset drive mode switching conditions. Execute the driver mode switching strategy; The execution drive mode switching strategy includes: Based on PI control, the front motor is engaged and its speed is controlled. Based on the speed control completion, the front axle connection device is engaged and controlled, so that the vehicle switches from two-wheel drive mode to four-wheel drive mode. Among them, the front motor is subjected to combined front speed control based on PI control, including: The output speed of the front axle connection device is obtained based on the current vehicle speed. Determine the pre-engagement speed based on vehicle speed and vehicle acceleration; The first target speed of the front motor is determined based on the output speed and the pre-applied engagement speed. The front motor is controlled by PI control according to the first target speed. The engagement control of the front axle connection device based on the speed control completion rate includes: Calculate the speed difference based on the output speed and the actual speed of the front motor; Whether to output a engagement control signal is determined based on the pre-applied engagement speed, the speed difference, and the duration of the speed difference; or... The front axle connection device is disconnected based on torque distribution. After the front axle connection device is disconnected, the speed of the front motor is controlled based on PI control to switch the vehicle from four-wheel drive mode to two-wheel drive mode. Specifically, before the front axle connection device is completely disconnected, the front motor is controlled to output oscillating torque according to the current vehicle speed.

2. The method according to claim 1, characterized in that, When the driving mode is Eco mode, the preset drive mode switching conditions include at least one of the following: Vehicle stability system integration; The road adhesion coefficient is less than the first preset adhesion coefficient; The battery's permissible power is less than the first preset low power threshold; The battery's allowable power is greater than the first preset low power threshold, and the throttle opening is greater than the preset throttle opening threshold.

3. The method according to claim 1, characterized in that, When the driving mode is comfort mode, the preset drive mode switching conditions include at least one of the following: Vehicle stability system integration; The road adhesion coefficient is less than the second preset adhesion coefficient; The battery's permissible power is less than the second preset low power threshold; The current vehicle speed is greater than the preset vehicle speed threshold; The battery's allowable power is greater than the second preset low power threshold, and the required torque is greater than the current maximum available output torque of the rear motor.

4. The method according to claim 1, characterized in that, Disconnection control of the front axle connection device based on torque distribution includes: Obtain the output torque of the front motor and distribute the output torque of the front motor to the rear motor; Whether to output a disconnection control signal is determined based on the output torque of the front motor and the preset disconnection torque.

5. The method according to claim 1, characterized in that, After the front axle connection is disconnected, the front motor speed is controlled based on PI control, including: Zero speed is taken as the second target speed of the front motor; The front motor is controlled by PI control based on the second target speed.

6. The method according to any one of claims 1 to 5, characterized in that, The acquisition of the vehicle's driving mode and operating condition parameters includes: The driving mode is determined based on any one or more of the following: the output speed of the front axle connection device, the current vehicle speed, or the required torque; and / or, The driving mode is determined based on the driving mode flag.

7. A vehicle powertrain control device, wherein the vehicle operates in two-wheel drive mode or four-wheel drive mode, the powertrain comprising a front-mounted motor, a front axle connection device, and a rear-mounted motor, characterized in that, For performing the vehicle powertrain control method according to any one of claims 1 to 6, the control device comprises: The parameter acquisition module is used to acquire the driving mode and operating condition parameters of the vehicle, including the driving mode, comfort mode and sport mode. The switching condition acquisition module is used to acquire preset driving mode switching conditions, which are set differently based on different driving modes. The decision module is used to determine the drive mode switching strategy based on the driving mode, the operating condition parameters and the preset drive mode switching conditions; The drive mode switching strategy includes: Based on PI control, the front motor is engaged and its speed is controlled. Based on the speed control completion, the front axle connection device is engaged and controlled, so that the vehicle switches from two-wheel drive mode to four-wheel drive mode. Among them, the front motor is subjected to combined front speed control based on PI control, including: The output speed of the front axle connection device is obtained based on the current vehicle speed. Determine the pre-engagement speed based on vehicle speed and vehicle acceleration; The first target speed of the front motor is determined based on the output speed and the pre-applied engagement speed. The front motor is controlled by PI control according to the first target speed. The engagement control of the front axle connection device based on the speed control completion rate includes: Calculate the speed difference based on the output speed and the actual speed of the front motor; Whether to output a engagement control signal is determined based on the pre-applied engagement speed, the speed difference, and the duration of the speed difference; and... The front axle connection device is disconnected based on torque distribution. After the front axle connection device is disconnected, the speed of the front motor is controlled based on PI control to switch the vehicle from four-wheel drive mode to two-wheel drive mode. Specifically, before the front axle connection device is completely disconnected, the front motor is controlled to output oscillating torque according to the current vehicle speed.

8. An electric vehicle, characterized in that, include: The vehicle powertrain control device as described in claim 7.

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