Torque distribution method of electric automobile and electric automobile

Abstract

The invention provides a torque distribution method of an electric vehicle and the electric vehicle. When the electric vehicle is in a forward state, torque is distributed to the first motor and the second motor through the first torque distribution relation; the first torque distribution relation is a corresponding relation between the vehicle speed and the torque of the electric vehicle and torques distributed by the first motor and the second motor when the total efficiency of the first motor and the second motor is the highest, and the torques distributed by the first motor and the second motor are positive torques or negative torques; when the electric vehicle is in a non-advancing state, torque is distributed to the first motor and the second motor through the second torque distribution relation; the second torque distribution relation is the corresponding relation between the vehicle speed and the torque of the electric vehicle and the torque distributed by the first motor and the second motor when the total efficiency of the first motor and the second motor is the highest, and the torque distributed by the first motor and the second motor comprises the positive torque and the negative torque. The efficiency of the power system of the electric automobile can be improved.

Description

Technical Field

[0001] The present application relates to the field of automobile control technology, and in particular to a torque distribution method of an electric vehicle and the electric vehicle. Background Art

[0002] For electric vehicles with dual-axle drive, the torque distribution between the dual motors directly affects the range and energy consumption of the electric vehicle. In actual operation, the working efficiency of the motor will change dynamically with factors such as vehicle speed and required torque. Unreasonable torque distribution may cause some motors to work in the low-efficiency range for a long time, which not only wastes electricity but also affects the power performance of the entire vehicle.

[0003] Existing torque distribution methods usually distribute the required torque evenly to the dual-axis motors. This distribution method is simple and easy to implement, but it cannot ensure that both motors work in a high efficiency range, and cannot ensure that the total efficiency of the dual motors is the highest, thereby increasing the energy consumption of electric vehicles. Summary of the invention

[0004] The present application provides a torque distribution method for an electric vehicle with high efficiency and the electric vehicle.

[0005] The present application provides a torque distribution method for an electric vehicle, wherein the electric vehicle includes a first motor and a second motor, and the torque distribution method includes:

[0006] Acquire the driving state, current vehicle speed and required torque of the electric vehicle; the driving state includes a forward state and a non-forward state;

[0007] When the electric vehicle is in the forward state, torque is allocated to the first motor and the second motor through a first torque allocation relationship; the first torque allocation relationship is: when the total efficiency of the first motor and the second motor is the highest, the corresponding relationship between the speed and torque of the electric vehicle and the torque allocated by the first motor and the second motor, wherein the torque allocated by the first motor and the second motor are both positive torques or both negative torques;

[0008] When the electric vehicle is in the non-forward state, torque is allocated to the first motor and the second motor through a second torque distribution relationship; the second torque distribution relationship is: when the total efficiency of the first motor and the second motor is the highest, the correspondence between the vehicle speed, torque and the torque allocated to the first motor and the second motor of the electric vehicle, wherein the torque allocated to the first motor and the second motor includes positive torque and negative torque.

[0009] Optionally, when the electric vehicle is in the forward state, distributing torque to the first motor and the second motor according to a first torque distribution relationship includes:

[0010] When the electric vehicle is in the forward state, the current vehicle speed and the required torque are substituted into the first torque distribution relationship to obtain a corresponding torque distribution coefficient; the torque distribution coefficient is a ratio of the torque distributed by the first motor to the required torque;

[0011] Allocating torque to the first motor and the second motor according to the torque distribution coefficient;

[0012] The first torque distribution relationship is: the correspondence between the vehicle speed, torque and torque distribution coefficient of the electric vehicle when the total efficiency of the first motor and the second motor is the highest; the torque distribution coefficient indicates that the torque distributed by the first motor and the second motor are both positive torque or both negative torque.

[0013] Optionally, when the electric vehicle is in the forward state, substituting the current vehicle speed and the required torque into the first torque distribution relationship to obtain a corresponding torque distribution coefficient includes:

[0014] When the electric vehicle is in the forward state for a preset time, the current vehicle speed and the required torque are substituted into a first torque distribution relationship to obtain a corresponding torque distribution coefficient.

[0015] Optionally, allocating torque to the first motor and the second motor according to the torque distribution coefficient includes:

[0016] Determining a first torque allocated to the first motor and a second torque allocated to the second motor according to the torque allocation coefficient;

[0017] The output torque of the first motor is controlled to gradually reach the first torque, and the output torque of the second motor is controlled to gradually reach the second torque.

[0018] Optionally, controlling the output torque of the first motor to gradually reach the first torque, and controlling the output torque of the second motor to gradually reach the second torque, includes:

[0019] The output torque of the first motor is controlled to gradually increase or decrease a preset torque value until the first torque is reached, and the output torque of the second motor is controlled to gradually increase or decrease the preset torque value until the second torque is reached.

[0020] Optionally, the first torque distribution relationship is determined by the following steps:

[0021] Obtaining the maximum speed of the electric vehicle;

[0022] According to the maximum vehicle speed, the external characteristic curves of the first motor and the second motor, determining the minimum allowable torque and the maximum allowable torque that the first motor and the second motor are allowed to output when the speed of the electric vehicle is less than the maximum vehicle speed, the minimum allowable torque being the sum of the minimum torques that the first motor and the second motor are allowed to output, and the maximum allowable torque being the sum of the maximum torques that the first motor and the second motor are allowed to output;

[0023] According to a first preset step length, the speed of the electric vehicle is grouped within a range from zero to the maximum speed of the electric vehicle, and the torque is grouped within a range from the minimum allowable torque to the maximum allowable torque;

[0024] Arranging and combining the speeds and torques of the grouped electric vehicles;

[0025] According to a second preset step size, the torque distribution coefficients are grouped within a range from 0 to 1;

[0026] For each set of vehicle speed and torque, respectively calculating the total efficiency of the first motor and the second motor corresponding to each set of torque distribution coefficients;

[0027] The first torque distribution relationship exists between each set of vehicle speed, torque and torque distribution coefficient corresponding to the highest total efficiency.

[0028] Optionally, when the electric vehicle is in the non-forward state, distributing torque to the first motor and the second motor through a second torque distribution relationship includes:

[0029] When the electric vehicle is in the non-forward state, the current vehicle speed and the required torque are substituted into the second torque distribution relationship to obtain a corresponding distributed torque; the distributed torque is the torque distributed to the first motor;

[0030] Distributing torque to the first motor and the second motor according to the distributed torque;

[0031] The second torque distribution relationship is: the correspondence between the vehicle speed, torque and distributed torque of the electric vehicle when the total efficiency of the first motor and the second motor is the highest; the distributed torque indicates that the torque distributed by the first motor and the second motor includes positive torque and negative torque.

[0032] Optionally, the second torque distribution relationship is determined by the following steps:

[0033] Obtaining the maximum speed of the electric vehicle;

[0034] According to the maximum vehicle speed, the external characteristic curves of the first motor and the second motor, determining the maximum allowable torque and the minimum allowable torque that the first motor and the second motor are allowed to output when the speed of the electric vehicle is less than the maximum vehicle speed, the maximum allowable torque being the sum of the maximum torques that the first motor and the second motor are allowed to output, and the minimum allowable torque being the sum of the minimum torques that the first motor and the second motor are allowed to output;

[0035] According to a first preset step length, the speed of the electric vehicle is grouped within a range from zero to the maximum speed of the electric vehicle, and the torque is grouped within a range from the minimum allowable torque to the maximum allowable torque;

[0036] Arranging and combining the speeds and torques of the grouped electric vehicles;

[0037] Determining a maximum torque and a minimum torque allowed to be output by the first motor according to the maximum vehicle speed;

[0038] According to a second preset step length, the distributed torque is grouped within a range from a minimum torque allowed to be output by the first motor to a maximum torque allowed to be output;

[0039] For each set of vehicle speed and torque, respectively calculating the total efficiency of the first motor and the second motor corresponding to each set of distributed torque;

[0040] The second torque distribution relationship exists between each set of vehicle speed, torque and the distributed torque corresponding to the highest total efficiency.

[0041] The present application also provides a torque distribution device for an electric vehicle, comprising one or more processors, for implementing any of the torque distribution methods for an electric vehicle described above.

[0042] The present application also provides an electric vehicle, comprising:

[0043] First motor;

[0044] a second motor; and

[0045] The torque distribution device as described above is electrically connected to the first motor and the second motor.

[0046] In some embodiments, when the electric vehicle is in a forward state, torque is allocated to the first motor and the second motor through a first torque allocation relationship, in which the torques allocated to the first motor and the second motor are both positive torques or both negative torques, so that the total efficiency of the first motor and the second motor is the highest; when the electric vehicle is in a non-forward state, torque is allocated to the first motor and the second motor through a second torque allocation relationship, in which the torques allocated to the first motor and the second motor include positive torque and negative torque, so that the total efficiency of the first motor and the second motor is the highest. When the electric vehicle is in a forward state, one motor is allowed to output positive torque and the other motor outputs negative torque, and when the electric vehicle is in a non-forward state, both motors need to output positive torque or negative torque. According to the state of the electric vehicle, the torque is allocated according to different torque allocation relationships, so that no matter what state the electric vehicle is in, the total efficiency of the first motor and the second motor can be kept at the highest, which can improve the efficiency of the power system of the electric vehicle and reduce energy consumption.

[0047] 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

[0048] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0049] Figure 1 Shown is a schematic diagram of an embodiment of an electric vehicle of the present application.

[0050] Figure 2 Shown is a flow chart of an embodiment of a torque distribution method for an electric vehicle of the present application.

[0051] Figure 3 Shown is a structural block diagram of an embodiment of the torque distribution device of the present application. DETAILED DESCRIPTION

[0052] The present application provides a torque distribution method for an electric vehicle and an electric vehicle. The torque distribution method for an electric vehicle and the electric vehicle of the present application are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0053] Figure 1 FIG. 1 is a schematic diagram of an embodiment of an electric vehicle 10 of the present application. Figure 1 As shown, the electric vehicle 10 includes: a first motor 11 , a second motor 12 and a torque distribution device 13 .

[0054] The electric vehicle 10 includes a front axle and a rear axle. Figure 1 In the illustrated embodiment, the first motor 11 is located at the front axle of the electric vehicle 10, and the second motor 12 is located at the rear axle of the electric vehicle 10. The first motor 11 is a front drive motor, and the second motor 12 is a rear drive motor. In other embodiments, the first motor 11 is located at the rear axle of the electric vehicle 10, and the second motor 12 is located at the front axle of the electric vehicle 10.

[0055] The working modes of the electric vehicle 10 include a forward mode and a non-forward mode. Among them, the non-forward mode includes a steering mode, a reverse mode, etc. When the vehicle is in the forward mode, the driving modes of the dual-axis power system may include the following: dual-axis simultaneous driving or braking, single-axis driving or braking, one axis driving the other axis braking. When the vehicle is in the non-forward mode, the driving modes of the dual-axis power system may include the following: dual-axis simultaneous driving or braking, single-axis driving or braking. When the vehicle is in the non-forward mode, the dual-axis motor cannot drive one axis to brake the other axis.

[0056] The torque distribution device 13 is electrically connected to the first motor 11 and the second motor 12, and is used to implement the torque distribution method of the electric vehicle provided in the present application. The torque distribution device 13 is used to distribute torque to the first motor 11 and the second motor 12. The torque distribution device 13 may include a first motor controller and a second motor controller, the first motor controller is electrically connected to the first motor 11, and the second motor controller is electrically connected to the second motor 12. The torque distribution device 13 can also be a VCU (Vehicle Control Unit) and / or a TCU (Transmission Control Unit) of the electric vehicle 10. In some embodiments, the VCU determines the required torque of the vehicle and sends it to the TCU, which performs torque distribution.

[0057] Figure 2 FIG. 2 is a flow chart of an embodiment of a torque distribution method 20 for an electric vehicle of the present application. Figure 2 As shown, the torque distribution method 20 of the electric vehicle includes: steps 21 to 24.

[0058] Step 21, obtaining the driving state, current vehicle speed and required torque of the electric vehicle.

[0059] The driving state includes a forward state and a non-forward state. The electric vehicle 10 includes a variety of sensors, such as a wheel speed sensor, a steering angle sensor, an acceleration sensor, and a gear position sensor. The torque distribution device 13 can obtain the driving state of the electric vehicle based on the signals of these sensors. For example, by combining the data of the gear position sensor and the wheel speed sensor, it can be determined whether the vehicle is in a forward state or a non-forward state such as reversing. By combining the data of the steering angle sensor and the wheel speed sensor, it can be determined whether the vehicle is in a steering state. The current speed of the vehicle can be obtained through the wheel speed sensor. The required torque of the vehicle can be obtained through the accelerator pedal position sensor, the brake pedal position sensor and the gear position sensor.

[0060] Step 22, determining the driving state of the electric vehicle.

[0061] According to the driving state of the electric vehicle acquired in step 21 , different measures are taken when the electric vehicle is in a forward state and a non-forward state.

[0062] Step 23, when the electric vehicle is in a forward state, torque is distributed to the first motor and the second motor according to a first torque distribution relationship.

[0063] The first torque distribution relationship is: when the total efficiency of the first motor and the second motor is the highest, the corresponding relationship between the speed, torque and the torque allocated to the first motor and the second motor of the electric vehicle, wherein the torque allocated to the first motor and the second motor is both positive torque or both negative torque. The first torque distribution relationship is the relationship between the speed, torque and the torque allocated to the first motor and the second motor of the vehicle, and the first torque distribution relationship can ensure the highest total efficiency of the first motor and the second motor. The first torque distribution relationship is a distribution relationship obtained in advance through experiments or experience. The first torque distribution relationship is stored in the torque distribution device 13. When the driving state of the vehicle is obtained as the forward state, the current vehicle speed and the required torque are substituted into the first torque distribution relationship to obtain the torque allocated to the first motor and the second motor corresponding to the current vehicle speed and the required torque. In this way, when the vehicle is in the forward state, the total efficiency of the first motor and the second motor can be maximized, the efficiency of the vehicle power system is improved, and energy consumption can be reduced.

[0064] Step 24, when the electric vehicle is in a non-forward state, torque is distributed to the first motor and the second motor through a second torque distribution relationship.

[0065] The second torque distribution relationship is: when the total efficiency of the first motor and the second motor is the highest, the corresponding relationship between the speed and torque of the electric vehicle and the torque allocated to the first motor and the second motor, wherein the torque allocated to the first motor and the second motor includes positive torque and negative torque. The second torque distribution relationship is the relationship between the vehicle speed, torque and the torque allocated to the first motor and the second motor, and the second torque distribution relationship can ensure the highest total efficiency of the first motor and the second motor. The second torque distribution relationship is a distribution relationship obtained in advance through experiments or experience. The second torque distribution relationship is stored in the torque distribution device 13. When the driving state of the vehicle is obtained as a non-advancing state, the current vehicle speed and the required torque are substituted into the second torque distribution relationship to obtain the torque allocated to the first motor and the second motor corresponding to the current vehicle speed and the required torque. In this way, when the vehicle is in a non-advancing state, the total efficiency of the first motor and the second motor can be maximized, the efficiency of the vehicle power system is improved, and energy consumption can be reduced.

[0066] In the first torque distribution relationship and the second torque distribution relationship, for the same current vehicle speed and required torque, the torques distributed to the corresponding first motor and second motor may be the same or different.

[0067] When the electric vehicle is in the forward state, one motor is allowed to output positive torque and the other motor is allowed to output negative torque. When the electric vehicle is not in the forward state, both motors need to output positive torque or negative torque. The driving state of the electric vehicle is different, and when the total efficiency of the two motors is the highest, the torque allocated to the two motors may be different. When the electric vehicle is in the forward state and the total efficiency of the power system is the highest, both motors may output positive torque or negative torque, or one motor may output positive torque and the other motor may output negative torque. When the electric vehicle is not in the forward state and the total efficiency of the power system is the highest, both motors may output positive torque or negative torque, but one motor cannot output positive torque and the other motor cannot output negative torque. Therefore, for different driving states of the vehicle, if the torque is distributed according to the same torque distribution relationship, it cannot be guaranteed that the power system efficiency can be maximized no matter what state the vehicle is in.

[0068] By distributing the torque according to different torque distribution relationships based on the state of the electric vehicle, the total efficiency of the first motor and the second motor can be maintained at the highest regardless of the state of the electric vehicle, thereby improving the efficiency of the power system of the electric vehicle and reducing energy consumption.

[0069] In some embodiments, step 23 includes: when the electric vehicle is in a forward state, substituting the current vehicle speed and required torque into the first torque distribution relationship to obtain a corresponding torque distribution coefficient; the torque distribution coefficient is the ratio of the torque allocated by the first motor to the required torque; according to the torque distribution coefficient, torque is distributed to the first motor and the second motor; the first torque distribution relationship is: when the total efficiency of the first motor and the second motor is the highest, the corresponding relationship between the vehicle speed, torque and torque distribution coefficient of the electric vehicle; the torque distribution coefficient indicates that the torques allocated by the first motor and the second motor are both positive torques or both negative torques.

[0070] When the electric vehicle is in a forward state, the first motor and the second motor can be driven or braked at the same time, that is, the torques allocated by the first motor and the second motor are both positive torques or both negative torques. The first torque distribution relationship can be obtained through experiments or experience. For example, for different vehicle speeds and required torques, the total efficiency of the first motor and the second motor corresponding to different torque distribution coefficients is calculated, and the torque distribution coefficient corresponding to the highest total efficiency is used as the torque distribution coefficient corresponding to the vehicle speed and the required torque of the group to form the first torque distribution relationship. Substituting the current vehicle speed and the required torque into the first torque distribution relationship, the corresponding torque distribution coefficient can be obtained by table lookup, interpolation and other methods. For example, according to the speed range of the current vehicle speed and the torque range of the required torque, the corresponding torque distribution coefficient is found in the first torque distribution relationship. In this way, the torque can be simply and quickly allocated to the first motor and the second motor, and the total efficiency can be maximized.

[0071] In some embodiments, when the electric vehicle is in a forward state, the current vehicle speed and the required torque are substituted into a first torque distribution relationship to obtain a corresponding torque distribution coefficient, including: when the electric vehicle is in a forward state for a preset time, the current vehicle speed and the required torque are substituted into the first torque distribution relationship to obtain a corresponding torque distribution coefficient.

[0072] When the electric vehicle is in a forward state, the torque is not immediately distributed to the first motor and the second motor according to the first torque distribution relationship, but after the electric vehicle is in a forward state for a preset time, the torque distribution is performed, which can prevent the vehicle's torque from changing too frequently and improve the driving experience. The preset time can be calibrated according to the vehicle model or application scenario.

[0073] In some embodiments, distributing torque to the first motor and the second motor according to the torque distribution coefficient includes: determining a first torque allocated to the first motor and a second torque allocated to the second motor according to the torque distribution coefficient; controlling the output torque of the first motor to gradually reach the first torque, and controlling the output torque of the second motor to gradually reach the second torque.

[0074] In some embodiments, the time length for the output torque of the first motor to reach the first torque and the time length for the output torque of the second motor to reach the second torque is a fixed value, and within this time length, the output torque of the motor is gradually converted into the target torque of the motor. In other embodiments, the step length of the output torque of the motor is a fixed value, and according to this step length, the output torque of the motor gradually reaches the target torque of the motor.

[0075] In actual control, the rate of change of the motor's output torque can be detected in real time. If the rate of change is greater than the rate of change threshold, the motor's output torque is controlled to slow down the change and change according to the preset step size. In this way, the vehicle's torque can be prevented from changing too frequently, the motor's service life can be extended, and the driving experience can be improved.

[0076] In some embodiments, controlling the output torque of the first motor to gradually reach a first torque, and controlling the output torque of the second motor to gradually reach a second torque, includes: controlling the output torque of the first motor to gradually increase or decrease a preset torque value until the first torque is reached, and controlling the output torque of the second motor to gradually increase or decrease a preset torque value until the second torque is reached.

[0077] The preset torque value indicates the magnitude of each adjustment. The preset torque value can be reasonably set according to the performance parameters of the motor (such as maximum power, maximum torque, torque response speed, etc.), the driving state of the vehicle (such as the preset torque value is smaller when driving at low speed, and the preset torque value is larger when driving at high speed), and the accuracy requirements of the control system. If the preset torque value is set too large, the adjustment of the motor output torque may be too drastic, causing unstable vehicle power output and even impacting the motor and vehicle's transmission system. If the preset torque value is set too small, although the adjustment process will be smoother, it may take too long to adjust, affecting the vehicle's real-time response to power demand.

[0078] If the current torque of the motor is greater than its target torque, the output torque of the motor is controlled to gradually decrease by a preset torque value until the target torque is reached. If the current torque of the motor is less than its target torque, the output torque of the motor is controlled to gradually increase by a preset torque value until the target torque is reached. In this way, the output torque of the motor can be more smoothly transitioned to the target value, avoiding the adverse effects of torque mutation on the vehicle power system and driving stability, and improving driving comfort.

[0079] In some embodiments, the first torque distribution relationship is determined by the following steps: obtaining the maximum speed of the electric vehicle; determining the minimum allowable torque and the maximum allowable torque that the first motor and the second motor are allowed to output when the speed of the electric vehicle is less than the maximum speed based on the external characteristic curves of the maximum speed, the first motor and the second motor, the minimum allowable torque being the sum of the minimum torques allowed to be output by the first motor and the second motor, and the maximum allowable torque being the sum of the maximum torques allowed to be output by the first motor and the second motor; grouping the speeds of the electric vehicle within the range of zero to the maximum speed of the electric vehicle according to a first preset step size, and grouping the torques within the range of the minimum allowable torque to the maximum allowable torque; arranging and combining the speeds and torques of the grouped electric vehicles; grouping the torque distribution coefficients within the range of 0 to 1 according to a second preset step size; for each group of speeds and torques, respectively calculating the total efficiency of the first motor and the second motor corresponding to each group of torque distribution coefficients; there is a first torque distribution relationship between each group of speeds, torques and the torque distribution coefficient corresponding to the highest total efficiency.

[0080] The torque distribution coefficient is used to indicate how the required torque is distributed between the first motor and the second motor. For example, if the required torque is 100 N·m and the first motor is allocated 30 N·m of torque, then the torque distribution coefficient is 0.3. In order to ensure that the first motor and the second motor output positive or negative torque at the same time, the torque distribution coefficient has a value range of [0,1].

[0081] The maximum speed can be obtained by consulting the vehicle's technical manual.

[0082] The external characteristic curves of the first motor and the second motor reflect the output capacity of the motor under different working conditions (such as different speeds), including the relationship between the output torque and the speed. By analyzing the external characteristic curves and combining the maximum vehicle speed, the torque range allowed to be output by the first motor and the second motor can be determined under all possible working conditions where the vehicle speed is less than the maximum vehicle speed.

[0083] The relationship between the total efficiency of the first motor and the second motor, the torque distribution coefficient, the vehicle speed, and the required torque can be expressed by formulas (1) to (7).

[0084] η=(P fmec +P rmec ) / (P fele +P rele ) Formula (1)

[0085] P fmec =P fele *η fmec Formula (2)

[0086] P rmec =P rele *ηrmec Formula (3)

[0087] P fmec +P rmec =[n f (1-λ)T+n r *λ*T] / 9550 Formula (4)

[0088] P fele +P rele =[η rmec *n f (1-λ)T+η fmec *n r λT] / (9550*η fmec *η rmec ) Formula (5)

[0089] v=0.12πrn / i Formula (6)

[0090] η={η f *η r [i f (1-λ)T+i r *λ*T]} / (η r *i f (1-λ)T+η f *i r *λ*T) Formula (7)

[0091] Where η is the total efficiency, P fmec is the mechanical power of the first motor, P rmec is the mechanical power of the second motor, P fele is the bus input power of the first motor, P rele is the bus input power of the second motor, η fmec is the efficiency of the first motor, η rmec is the efficiency of the second motor, T is the required torque, n f is the first motor speed, n r is the speed of the second motor, λ is the torque distribution coefficient, v is the vehicle speed, r is the tire radius, i is the reduction ratio, i f is the front axle reduction ratio, i r is the rear axle reduction ratio.

[0092] Substituting the vehicle speed, required torque, and different torque distribution coefficients into formula (7), the total efficiency corresponding to different torque distribution coefficients at the current vehicle speed and required torque can be obtained.

[0093] In the process of determining the torque distribution coefficient with the highest total efficiency, the vehicle speed, torque, and torque distribution coefficient are first divided into grids. For example, the first preset step size is set to 10km / h, and the maximum vehicle speed is 120km / h, then the grid points where the vehicle speed is divided are [10,20,…110,120]. The torque range allowed to be output by the first motor is [-200,200], and the torque range allowed to be output by the second motor is [-300,300]. The range from the minimum allowable torque to the maximum allowable torque is [-500,500], and the torque grid points are [-500,-490,…490,500]. For the grouped vehicle speed and torque permutations, all possible combinations are enumerated, and each combination represents a working condition that the vehicle may encounter in actual driving. In some embodiments, the rotation speeds of the first motor and the second motor can also be determined based on the vehicle speed, and the external characteristic curve of the motor is used to obtain the maximum motor torque corresponding to the current rotation speed, thereby eliminating the torque combination that the vehicle speed cannot correspond to and reducing the calculation complexity. The second preset step size is set to 0.1, and the torque distribution coefficient grid points are [0, 0.1, 0.2, ... 0.9, 1].

[0094] For each combination of vehicle speed and torque conditions, the total efficiency of the first motor and the second motor corresponding to each set of torque distribution coefficients is calculated respectively. That is, under each vehicle speed and torque condition, the above 10 different torque distribution schemes are considered. Substituting the vehicle speed, torque, and torque distribution coefficient into formula (7), the corresponding total efficiency can be obtained. For example, under the condition of a vehicle speed of 60 km / h and a torque of 120 N·m, when the torque distribution coefficient is 0.2, the total efficiency of the first motor and the second motor is calculated to be 80%; when the torque distribution coefficient is 0.3, the total efficiency is 82%, etc.

[0095] Under each vehicle speed and torque condition, find the torque distribution coefficient corresponding to the highest total efficiency. A first torque distribution relationship is established between each set of vehicle speed, torque and the torque distribution coefficient corresponding to the highest total efficiency. The first torque distribution relationship can be presented in the form of a table, a curve or a mathematical model.

[0096] Through the above method, the first torque distribution relationship can be determined relatively quickly and accurately, thereby improving the overall efficiency of the vehicle during driving.

[0097] In some embodiments, step 24 includes: when the electric vehicle is in a non-forward state, substituting the current vehicle speed and required torque into the second torque distribution relationship to obtain the corresponding distributed torque; the distributed torque is the torque distributed to the first motor; according to the distributed torque, the torque is distributed to the first motor and the second motor; the second torque distribution relationship is: when the total efficiency of the first motor and the second motor is the highest, the correspondence between the vehicle speed, torque and distributed torque of the electric vehicle; the distributed torque indicates that the torque distributed by the first motor and the second motor includes positive torque and negative torque.

[0098] When the electric vehicle is in a non-advancing state, the first motor and the second motor can be driven or braked at the same time, or one motor can be driven and the other motor can be braked, that is, the torque allocated by the first motor and the second motor can be a positive torque or a negative torque. The second torque distribution relationship can be obtained through experiments or experience. For example, for different vehicle speeds and required torques, the total efficiency of the first motor and the second motor corresponding to different allocated torques is calculated, and the allocated torque corresponding to the highest total efficiency is used as the allocated torque corresponding to the group of vehicle speeds and required torques to form the second torque distribution relationship. Substituting the current vehicle speed and the required torque into the second torque distribution relationship, the corresponding allocated torque can be obtained by table lookup, interpolation and other methods. For example, according to the vehicle speed interval of the current vehicle speed and the torque interval of the required torque, the corresponding allocated torque is found in the second torque distribution relationship. In this way, the torque can be simply and quickly allocated to the first motor and the second motor, and the total efficiency can be maximized.

[0099] In some embodiments, the second torque distribution relationship is determined by the following steps: obtaining the maximum speed of the electric vehicle; determining the maximum allowable torque and the minimum allowable torque that the first motor and the second motor are allowed to output when the speed of the electric vehicle is less than the maximum speed according to the maximum speed, the external characteristic curves of the first motor and the second motor, the maximum allowable torque being the sum of the maximum torques allowed to be output by the first motor and the second motor, and the minimum allowable torque being the sum of the minimum torques allowed to be output by the first motor and the second motor; grouping the speeds of the electric vehicle within the range of zero to the maximum speed of the electric vehicle according to a first preset step size, and grouping the torques within the range of the minimum allowable torque to the maximum allowable torque; arranging and combining the speeds and torques of the grouped electric vehicles; determining the maximum torque and the minimum torque allowed to be output by the first motor according to the maximum speed; grouping the distributed torques within the range of the minimum torque allowed to be output by the first motor to the maximum torque allowed to be output according to a second preset step size; for each group of speeds and torques, respectively calculating the total efficiency of the first motor and the second motor corresponding to each group of distributed torques; there is a second torque distribution relationship between each group of speeds, torques and the distributed torque corresponding to the highest total efficiency.

[0100] The relationship between the total efficiency of the first motor and the second motor, the distributed torque of the first motor, the distributed torque of the second motor, the vehicle speed, and the required torque can be expressed by formula (8).

[0101] η=(η f *i f *T f +η r *v*i r *T r ) / (i f *T f +i r *T r ) Formula (8)

[0102] Among them, T f is the torque distributed to the first motor, T r The torque distributed to the second motor.

[0103] The process of dividing the grid for vehicle speed and required torque can be referred to above. Obtain the minimum torque and maximum torque of the first motor, and divide the grid for the distributed torque according to the second preset step size. For example, the torque range allowed to be output by the first motor is [-200, 200], the second preset step size is 10N·m, and the grid points for the distributed torque are [-200, -190, -180, ... 190, 200].

[0104] For each combination of vehicle speed and torque conditions, the total efficiency of the first motor and the second motor corresponding to each set of distributed torque is calculated respectively. Substituting the vehicle speed, torque and distributed torque into formula (8), the corresponding total efficiency can be obtained.

[0105] Under each vehicle speed and torque condition, find the corresponding distributed torque when the total efficiency is the highest. A second torque distribution relationship is established between each set of vehicle speed, torque and the distributed torque corresponding to the highest total efficiency. The second torque distribution relationship can be presented in the form of a table, a curve or a mathematical model.

[0106] Through the above method, the second torque distribution relationship can be determined relatively quickly and accurately, thereby improving the overall efficiency of the vehicle during driving.

[0107] In some embodiments, the torque distribution method 20 further includes: when one of the first motor and the second motor outputs positive torque and the other outputs negative torque, if the sum of the absolute values ​​of the torques output by the first motor and the second motor is greater than the torque threshold, the first motor and the second motor are controlled to output torques in the same direction according to the required torque. In this way, excessive stretching of the vehicle chassis can be prevented, thereby improving vehicle safety.

[0108] Figure 3 Shown is a structural block diagram of an embodiment of the torque distribution device of the present application.

[0109] like Figure 3 As shown, the torque distribution device includes one or more processors 31 for implementing the torque distribution method 20 for the electric vehicle as described above.

[0110] In some embodiments, the torque distribution device may include a computer-readable storage medium 32, which may store a program that can be called by the processor 31 and may include a non-volatile storage medium. In some embodiments, the torque distribution device may include a memory 33 and an interface 34. In some embodiments, the torque distribution device may also include other hardware according to actual applications.

[0111] The computer-readable storage medium 32 of the embodiment of the present application stores a program thereon, and when the program is executed by the processor 31, it is used to implement the torque distribution method 20 of the electric vehicle described above.

[0112] The present application may take the form of a computer program product implemented on one or more computer-readable storage media 32 (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing program code. The computer-readable storage medium 32 includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. The information can be a computer-readable instruction, a data structure, a module of a program, or other data. Examples of computer-readable storage media 32 include but are not limited to: phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassette, tape disk storage or other magnetic storage device or any other non-transmission medium that can be used to store information that can be accessed by a computing device.

Claims

1. A torque distribution method for an electric vehicle, characterized in that: The electric vehicle includes a first motor and a second motor, and the torque distribution method includes: Acquire the driving state, current vehicle speed and required torque of the electric vehicle; the driving state includes a forward state and a non-forward state; When the electric vehicle is in the forward state, torque is allocated to the first motor and the second motor through a first torque allocation relationship; the first torque allocation relationship is: when the total efficiency of the first motor and the second motor is the highest, the corresponding relationship between the speed and torque of the electric vehicle and the torque allocated by the first motor and the second motor, wherein the torque allocated by the first motor and the second motor are both positive torques or both negative torques; When the electric vehicle is in the non-forward state, torque is allocated to the first motor and the second motor through a second torque distribution relationship; the second torque distribution relationship is: when the total efficiency of the first motor and the second motor is the highest, the correspondence between the vehicle speed, torque and the torque allocated to the first motor and the second motor of the electric vehicle, wherein the torque allocated to the first motor and the second motor includes positive torque and negative torque.

2. The torque distribution method of an electric vehicle according to claim 1, characterized in that: When the electric vehicle is in the forward state, the torque is distributed to the first motor and the second motor according to the current vehicle speed and the required torque through a first torque distribution relationship, including: When the electric vehicle is in the forward state, the current vehicle speed and the required torque are substituted into the first torque distribution relationship to obtain a corresponding torque distribution coefficient; the torque distribution coefficient is a ratio of the torque distributed by the first motor to the required torque; Allocating torque to the first motor and the second motor according to the torque distribution coefficient; The first torque distribution relationship is: the correspondence between the vehicle speed, torque and torque distribution coefficient of the electric vehicle when the total efficiency of the first motor and the second motor is the highest; the torque distribution coefficient indicates that the torque distributed by the first motor and the second motor are both positive torque or both negative torque.

3. The torque distribution method of an electric vehicle according to claim 2, characterized in that: When the electric vehicle is in the forward state, the current vehicle speed and the required torque are substituted into the first torque distribution relationship to obtain a corresponding torque distribution coefficient, including: When the electric vehicle is in the forward state for a preset time, the current vehicle speed and the required torque are substituted into a first torque distribution relationship to obtain a corresponding torque distribution coefficient.

4. The torque distribution method of an electric vehicle according to claim 2, characterized in that: The allocating torque to the first motor and the second motor according to the torque allocation coefficient includes: Determining a first torque allocated to the first motor and a second torque allocated to the second motor according to the torque allocation coefficient; The output torque of the first motor is controlled to gradually reach the first torque, and the output torque of the second motor is controlled to gradually reach the second torque.

5. The torque distribution method of an electric vehicle according to claim 4, characterized in that: The step of controlling the output torque of the first motor to gradually reach the first torque, and controlling the output torque of the second motor to gradually reach the second torque, comprises: The output torque of the first motor is controlled to gradually increase or decrease a preset torque value until the first torque is reached, and the output torque of the second motor is controlled to gradually increase or decrease the preset torque value until the second torque is reached.

6. The torque distribution method of an electric vehicle according to claim 2, characterized in that: The first torque distribution relationship is determined by the following steps: Obtaining the maximum speed of the electric vehicle; According to the maximum vehicle speed, the external characteristic curves of the first motor and the second motor, determining the minimum allowable torque and the maximum allowable torque that the first motor and the second motor are allowed to output when the speed of the electric vehicle is less than the maximum vehicle speed, the minimum allowable torque being the sum of the minimum torques that the first motor and the second motor are allowed to output, and the maximum allowable torque being the sum of the maximum torques that the first motor and the second motor are allowed to output; According to a first preset step length, the speed of the electric vehicle is grouped within a range from zero to the maximum speed of the electric vehicle, and the torque is grouped within a range from the minimum allowable torque to the maximum allowable torque; Arranging and combining the speeds and torques of the grouped electric vehicles; According to a second preset step size, the torque distribution coefficients are grouped within a range from 0 to 1; For each set of vehicle speed and torque, respectively calculating the total efficiency of the first motor and the second motor corresponding to each set of torque distribution coefficients; The first torque distribution relationship exists between each set of vehicle speed, torque and torque distribution coefficient corresponding to the highest total efficiency.

7. The torque distribution method of an electric vehicle according to claim 1, characterized in that: When the electric vehicle is in the non-forward state, distributing torque to the first motor and the second motor through a second torque distribution relationship includes: When the electric vehicle is in the non-forward state, the current vehicle speed and the required torque are substituted into the second torque distribution relationship to obtain a corresponding distributed torque; the distributed torque is the torque distributed to the first motor; Distributing torque to the first motor and the second motor according to the distributed torque; The second torque distribution relationship is: the correspondence between the vehicle speed, torque and distributed torque of the electric vehicle when the total efficiency of the first motor and the second motor is the highest; the distributed torque indicates that the torque distributed by the first motor and the second motor includes positive torque and negative torque.

8. The torque distribution method of an electric vehicle according to claim 7, characterized in that: The second torque distribution relationship is determined by the following steps: Obtaining the maximum speed of the electric vehicle; According to the maximum vehicle speed, the external characteristic curves of the first motor and the second motor, determining the maximum allowable torque and the minimum allowable torque that the first motor and the second motor are allowed to output when the speed of the electric vehicle is less than the maximum vehicle speed, the maximum allowable torque being the sum of the maximum torques that the first motor and the second motor are allowed to output, and the minimum allowable torque being the sum of the minimum torques that the first motor and the second motor are allowed to output; According to a first preset step length, the speed of the electric vehicle is grouped within a range from zero to the maximum speed of the electric vehicle, and the torque is grouped within a range from the minimum allowable torque to the maximum allowable torque; Arranging and combining the speeds and torques of the grouped electric vehicles; Determining a maximum torque and a minimum torque allowed to be output by the first motor according to the maximum vehicle speed; According to a second preset step length, the distributed torque is grouped within a range from a minimum torque allowed to be output by the first motor to a maximum torque allowed to be output; For each set of vehicle speed and torque, respectively calculating the total efficiency of the first motor and the second motor corresponding to each set of distributed torque; The second torque distribution relationship exists between each set of vehicle speed, torque and the distributed torque corresponding to the highest total efficiency.

9. A torque distribution device for an electric vehicle, characterized in that: The invention comprises one or more processors for implementing the torque distribution method of the electric vehicle according to any one of claims 1 to 8.

10. An electric vehicle, characterized in that: include: First motor; Second motor; and The torque distribution device as described in claim 9 is electrically connected to the first motor and the second motor.

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