CN113829891B - Electric automobile and distributed torque distribution method and device thereof - Google Patents

Electric automobile and distributed torque distribution method and device thereof Download PDF

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Publication number
CN113829891B
CN113829891B CN202111064498.4A CN202111064498A CN113829891B CN 113829891 B CN113829891 B CN 113829891B CN 202111064498 A CN202111064498 A CN 202111064498A CN 113829891 B CN113829891 B CN 113829891B
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torque
motor
torque distribution
distribution coefficient
target
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CN113829891A (en
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王念
秦博
张泽阳
赵春来
王秋来
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Dongfeng Motor Corp
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Dongfeng Motor Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/32—Control or regulation of multiple-unit electrically-propelled vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2220/00—Electrical machine types; Structures or applications thereof
    • B60L2220/40—Electrical machine applications
    • B60L2220/42—Electrical machine applications with use of more than one motor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2220/00—Electrical machine types; Structures or applications thereof
    • B60L2220/40—Electrical machine applications
    • B60L2220/44—Wheel Hub motors, i.e. integrated in the wheel hub
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/421—Speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/423—Torque
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2250/00—Driver interactions
    • B60L2250/26—Driver interactions by pedal actuation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

Abstract

The invention discloses a distributed torque distribution method of an electric automobile, which comprises the following steps: in the running process of the vehicle, the current driver demand torque and the current rotating speed of the target motor are obtained; the target motor is a front shaft motor or a rear shaft motor of the vehicle; determining a target torque distribution coefficient according to the current rotating speed, the current driver demand torque and the mapping relation; the mapping relation is the corresponding relation between the motor rotating speed, the driver demand torque and the torque distribution coefficient; the target torque distribution coefficient is a torque distribution coefficient that satisfies a set condition for the total efficiency of the drive system of the host vehicle; and according to the target torque distribution coefficient and the current driver demand torque, the torque distribution of the vehicle is carried out. The torque distribution method can remarkably improve the energy economy of the electric vehicle.

Description

Electric automobile and distributed torque distribution method and device thereof
Technical Field
The application relates to the technical field of electric automobiles, in particular to an electric automobile and a distributed torque distribution method and device thereof.
Background
With the continuous and deep research of electric automobile technology, the arrangement structure of a driving system of an electric automobile gradually develops from a centralized driving system with a single power source to a distributed driving system with multiple power sources. The distributed driving electric automobile is mainly characterized in that a driving motor is directly arranged in a driving wheel (a hub motor) or near the driving wheel (a hub motor), transmission components such as a gear shifting control device and a clutch are omitted, a mechanical transmission chain is eliminated, and the distributed driving electric automobile has the outstanding advantages of short driving transmission chain, high transmission efficiency, compact structure and the like, and gradually becomes a hot point for research in the field of electric automobiles.
At present, a torque distribution control strategy based on distributed driving mainly focuses on improvement of vehicle stability performance and high-quality driving experience. For example, related art CN111746295a discloses a distributed drive control method of an electric vehicle, by acquiring a current driving mode and a current required torque of the vehicle, according to the current driving mode and the current required torque, in combination with a running state of the vehicle, torque instructions for controlling each in-wheel motor to output corresponding torque are respectively sent to a motor controller of each in-wheel motor. The torque control in the related art is mainly aimed at improving the driving performance of the vehicle, and has poor effect in terms of energy economy, such as improving the endurance mileage on the premise of unchanged electric quantity.
Disclosure of Invention
The invention provides an electric vehicle and a distributed torque distribution method and device thereof, which aim to solve or partially solve the technical problems that the torque control scheme of the electric vehicle adopting distributed driving is poor in economy and the cruising mileage of the electric vehicle is affected.
In order to solve the technical problems, the invention provides a distributed torque distribution method of an electric automobile, which comprises the following steps:
In the running process of the vehicle, the current driver demand torque and the current rotating speed of the target motor are obtained; the target motor is a front shaft motor or a rear shaft motor of the vehicle;
determining a target torque distribution coefficient according to the current rotating speed, the current driver demand torque and the mapping relation; the mapping relation is the corresponding relation between the motor rotating speed, the driver demand torque and the torque distribution coefficient; the target torque distribution coefficient is a torque distribution coefficient that satisfies a set condition for the total efficiency of the drive system of the host vehicle;
and according to the target torque distribution coefficient and the current driver demand torque, the torque distribution of the vehicle is carried out.
Optionally, the method for determining the mapping relationship includes:
obtaining a parameter data set; the parameter data set comprises N groups of calculation parameters, and each group of calculation parameters comprises a driver required torque and a target motor rotating speed; n is more than or equal to 2 and is an integer;
calculating according to each set of calculation parameters to obtain target torque distribution coefficients corresponding to each set of calculation parameters, wherein the target torque distribution coefficients comprise: for each group of calculation parameters, determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the target motor rotating speed, the driver demand torque and the plurality of candidate torque distribution coefficients; the candidate torque distribution coefficient is determined according to the target motor rotating speed and the driver demand torque; determining a candidate torque distribution coefficient corresponding to the total efficiency of a target driving system as the target torque distribution coefficient; the target drive system total efficiency is a drive system total efficiency that is not less than a set efficiency;
And obtaining the mapping relation according to each group of calculation parameters and the target torque distribution coefficient corresponding to each group of calculation parameters.
Further, the method for determining the candidate torque distribution coefficient comprises the following steps:
determining a first peak torque of a front axle motor and a second peak torque of the rear axle motor according to the target motor rotating speed;
determining a value data set of a torque distribution coefficient according to the first peak torque and the second peak torque of the driver demand torque; the value data set comprises M torque distribution coefficients to be selected, wherein M is more than or equal to 2 and is an integer.
Further, the front shaft motor is a centralized motor, and the rear shaft motor is a hub motor;
the determining a value data set of a torque distribution coefficient according to the driver demand torque, the first peak torque and the second peak torque includes:
determining a torque distribution coefficient upper limit value according to the driver demand torque, the first peak torque and a front axle motor reduction ratio;
determining a torque distribution coefficient lower limit value according to the driver demand torque and the second peak torque;
and determining the value data set according to the torque distribution coefficient lower limit value, the torque distribution coefficient upper limit value and a preset value interval.
Further, the determining the torque distribution coefficient upper limit value according to the driver demand torque, the first peak torque and the front axle motor reduction ratio includes:
obtaining a first calculated value; the first calculated value is determined from the product of the first peak torque and the front axle motor reduction ratio divided by the driver demand torque;
obtaining a first value to be selected; the first value to be selected is determined according to the sum of the rounded first calculated value and the preset value interval;
and determining the torque distribution coefficient upper limit value according to the minimum value between the first standby value and the first set value.
Further, the determining a lower limit value of a torque distribution coefficient according to the driver demand torque and the second peak torque includes:
obtaining a second calculated value; the second calculated value is determined according to the difference value between the set value and the torque ratio; the torque ratio is determined from the second peak torque and the driver demand torque;
obtaining a second value to be selected; the second value to be selected is determined according to the difference between the rounded second calculated value and the preset value interval;
and determining the lower limit value of the torque distribution coefficient according to the maximum value between the second candidate value and the second set value.
According to the above technical solution, according to the target motor rotation speed, the driver demand torque and a plurality of candidate torque distribution coefficients, determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient includes:
determining a front axle motor output torque and a rear axle motor output torque according to the candidate torque distribution coefficient and the driver demand torque;
determining front axle motor efficiency according to the target motor speed, the front axle motor output torque and front axle motor efficiency characteristic data;
determining rear axle motor efficiency according to the target motor speed, the rear axle motor output torque and the rear axle motor efficiency characteristic data;
and determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the front axle motor efficiency, the rear axle motor efficiency, the front axle motor output torque, the rear axle motor output torque and the target motor rotating speed.
According to another alternative embodiment of the present invention, there is provided a distributed torque distribution device for an electric vehicle, including:
the obtaining module is used for obtaining the current driver demand torque and the current rotating speed of the target motor in the running process of the vehicle; the target motor is a front shaft motor or a rear shaft motor of the vehicle;
The determining module is used for determining a target torque distribution coefficient according to the current rotating speed, the current driver demand torque and the mapping relation; the mapping relation is the corresponding relation between the motor rotating speed, the driver demand torque and the torque distribution coefficient; the target torque distribution coefficient is a torque distribution coefficient that satisfies a set condition for the total efficiency of the drive system of the host vehicle;
and the torque distribution module is used for distributing the torque of the vehicle according to the target torque distribution coefficient and the current driver demand torque.
According to a further alternative embodiment of the present invention, there is provided a vehicle control unit, including a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the allocation method according to any one of the preceding technical solutions when executing the computer program.
According to still another alternative embodiment of the present invention, an electric vehicle is provided, which includes the vehicle controller in the foregoing technical solution.
Through one or more technical schemes of the invention, the invention has the following beneficial effects or advantages:
The invention provides a distributed torque distribution method of an electric automobile, which comprises the steps of determining a target torque distribution coefficient matched with a current driving working condition from a mapping relation between a motor rotating speed, a required torque and a torque distribution coefficient according to the current driving working condition, namely, the required torque of a driver and the current rotating speed of a target motor in the running process of the electric automobile; the target torque distribution coefficient is a distribution coefficient of front and rear axle torques which is preset and is used for enabling the total efficiency of the driving system to meet the set condition as a target under the current driving working condition; the setting condition may be that the total efficiency value of the driving system under the current working condition is the highest, or that the total efficiency value of the driving system under the current working condition is greater than the recommended efficiency value of the vehicle; the working points of the front and rear shaft driving motors are adjusted by adopting the target torque distribution coefficient which enables the total efficiency of the driving system to be maintained at a higher level in the driving process, so that torque optimization distribution of the longitudinal torque in a generalized demand can be realized, the endurance mileage of the pure electric vehicle is improved under the condition that the electric quantity of a battery is fixed, and the energy economy of the electric vehicle is remarkably improved. On the other hand, the mapping relation is predetermined and applied to the torque distribution control strategy, so that the corresponding target torque distribution coefficient can be directly called under different driving working conditions, the aim of keeping the total efficiency of the driving system at a higher level can be achieved, the modeling complexity of the control strategy can be reduced, the real-time calculation workload is reduced, and the real-time performance of the torque distribution control under different driving working conditions is improved.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present invention more readily apparent.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 is a flow chart of a method for distributing distributed torque of an electric vehicle according to one embodiment of the invention;
FIG. 2 illustrates a map determination flow diagram of "motor speed-demand torque-torque distribution coefficient" according to one embodiment of the present invention;
FIG. 3 shows a schematic diagram of a distributed three motor drive system according to another embodiment of the present invention;
FIG. 4 illustrates a three-dimensional schematic of an efficiency characteristic of a concentrated motor-electric system in accordance with another embodiment of the invention;
FIG. 5 illustrates a value-added plot of efficiency characteristics of a concentrated motor electric system in accordance with another embodiment of the invention;
FIG. 6 is a three-dimensional schematic diagram illustrating efficiency characteristics of an electric system of an in-wheel motor in accordance with another embodiment of the present invention;
FIG. 7 is a value-added plot of efficiency characteristics of an electric system of an in-wheel motor in accordance with another embodiment of the present invention;
FIG. 8 is a schematic diagram showing a calculation flow of a target torque distribution coefficient according to another embodiment of the present invention;
fig. 9 shows a schematic view of an electric vehicle distributed torque distribution device according to still another embodiment of the present invention.
Detailed Description
In order to make the technical solution more clearly understood by those skilled in the art, the following detailed description is made with reference to the accompanying drawings. Throughout the specification, unless specifically indicated otherwise, the terms used herein should be understood as meaning as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification will control. The various devices and the like used in the present invention are commercially available or can be prepared by existing methods unless otherwise specifically indicated.
In order to improve the torque control economy of the distributed driving type electric vehicle and improve the endurance mileage of the distributed driving type electric vehicle, the invention provides a distribution method of the distributed torque of the electric vehicle, which has the following overall thought:
in the running process of the vehicle, the current driver demand torque and the current rotating speed of the target motor are obtained; the target motor is a front shaft motor or a rear shaft motor of the vehicle; determining a target torque distribution coefficient according to the current rotating speed, the current driver demand torque and the mapping relation; the mapping relation is the corresponding relation between the motor rotating speed, the driver demand torque and the torque distribution coefficient; the target torque distribution coefficient is a torque distribution coefficient that satisfies a set condition for the total efficiency of the drive system of the host vehicle; and according to the target torque distribution coefficient and the current driver demand torque, the torque distribution of the vehicle is carried out.
The control principle of the scheme is as follows: in the running process of the vehicle, according to the current driving working condition, namely the driver demand torque and the current rotating speed of the target motor, determining a target torque distribution coefficient matched with the current driving working condition from the mapping relation between the rotating speed of the motor, the demand torque and the torque distribution coefficient; the target torque distribution coefficient is a distribution coefficient of front and rear axle torques which is preset and is used for enabling the total efficiency of the driving system to meet the set condition as a target under the current driving working condition; the setting condition may be that the total efficiency value of the driving system under the current working condition is the highest, or that the total efficiency value of the driving system under the current working condition is greater than the recommended efficiency value of the vehicle; in the running process, the working points of the front and rear shaft driving motors are adjusted by adopting the target torque distribution coefficient which enables the total efficiency of the driving system to be maintained at a higher level, so that the torque optimization distribution of the longitudinal torque in the generalized demand can be realized, the endurance mileage of the pure electric vehicle is improved under the condition that the electric quantity of the battery is fixed, and the energy economy of the electric vehicle is obviously improved.
On the other hand, the mapping relation is predetermined and applied to the torque distribution control strategy, so that the corresponding target torque distribution coefficient can be directly called under different driving working conditions, the aim of keeping the total efficiency of the driving system at a higher level can be achieved, the modeling complexity of the control strategy can be reduced, the real-time calculation workload is reduced, and the real-time performance of the torque distribution control under different driving working conditions is improved.
The torque distribution scheme provided by the invention is suitable for a distributed driving scheme with inconsistent front and rear efficiency fields, wherein the front and rear efficiency fields are centralized motors, the front axle is a centralized motor, the rear axle is a hub motor, and the front and rear efficiency fields are hub motors. The scheme can be applied to an electronic control unit (Electronic Control Unit, ECU) of the electric automobile, a driving computer or a whole vehicle controller VCU.
In the following, the above-described embodiments will be described in detail with reference to the embodiments.
In an alternative embodiment, the allocation method includes:
s1: in the running process of the vehicle, the current driver demand torque and the current rotating speed of the target motor are obtained; the target motor is a front shaft motor or a rear shaft motor of the vehicle.
Specifically, the driver demand torque may be converted according to an accelerator pedal signal, that is, an accelerator pedal opening is obtained, and the driver demand torque is determined according to the accelerator pedal opening. The accelerator pedal opening may be obtained by a position sensor at the pedal.
The target motor may be a front axle drive motor or a rear axle drive motor. The driving motor may be a centralized motor or an in-wheel motor. For a determined vehicle model and a determined distributed drive scheme, a determined correspondence exists between the front axle drive motor speed and the rear axle drive motor speed during travel. Taking hub motors as an example, the front and rear shaft motors have the same rotating speed; taking a distributed driving scheme of taking a front shaft as a centralized motor and a rear shaft as a hub motor as an example, the two hub motors of the rear shaft have the same rotating speed; the front axle motor is provided with a speed reducer, so that when the slip rate is not considered, if the rotating speed of the front axle concentrated motor is obtained, the rotating speed of the rear axle hub motor can be obtained by dividing the rotating speed of the front axle motor by the speed reduction ratio; on the contrary, if the rotation speed of the rear axle hub motor is obtained, the rotation speed of the front axle hub motor can be obtained by multiplying the rotation speed of the rear axle motor by the reduction ratio. Therefore, in actual control, only the rotation speed of one of the front and rear shaft motors is required to be obtained, and the rotation speeds of the rest of the drive motors can be calculated.
S2: determining a target torque distribution coefficient according to the current rotating speed, the current driver demand torque and the mapping relation; the mapping relation is the corresponding relation between the motor rotating speed, the driver demand torque and the torque distribution coefficient; the target torque distribution coefficient is a torque distribution coefficient that satisfies a set condition for the total efficiency of the drive system of the host vehicle.
The current driving working condition refers to the driving working condition that the current driver demands torque and the current target motor is at the current rotating speed. The mapping relation comprises a plurality of motor rotating speed-required torque-torque distribution coefficient data pairs; the motor rotating speed and the required torque represent various possible or typical driving working conditions, the corresponding torque distribution coefficient is calculated in advance, and the total efficiency of a driving system of the motor vehicle can reach the highest torque distribution coefficient under each driving working condition, or the total efficiency value of the driving system under the current driving working condition is larger than the torque distribution coefficient applicable to the recommended efficiency value of the motor vehicle; the motor output torques of the front axle motor and the rear axle motor are distributed according to the target torque distribution coefficient and the current driver demand torque, and the total efficiency of the driving system of the motor vehicle under the current working condition can be highest or maintained at a relatively high efficiency level relative to other torque distribution coefficients.
The torque distribution coefficient K is defined as follows:
K＝T f /(T f +T r ) Or k=t r /(T f +T r )；
The torque split by the front and rear axles then satisfies:
T req ＝T f +T r ；
in the above, T f T for torque distributed to front axle wheels r T for torque distributed to rear axle wheels req Torque is demanded for the driver.
S3: and according to the target torque distribution coefficient and the current driver demand torque, the torque distribution of the vehicle is carried out.
After the target torque distribution coefficient matched with the current driving working condition and having the total efficiency of the optimal driving system is obtained, the front and rear axle torque is distributed by utilizing the target torque distribution coefficient, the working points of the front and rear axle driving motors can be adjusted according to the current driving working condition, so that the total efficiency of the driving system is the highest, the optimal distribution of the generalized demand longitudinal force is realized, and the economical efficiency of the vehicle is improved.
In order to improve the instantaneity of determining the target torque distribution coefficient and reduce the calculation workload, the map of the motor rotation speed to the required torque to the torque distribution coefficient is predetermined according to various possible driving conditions. As shown in fig. 2, an alternative scheme for determining the mapping relationship is as follows:
s01: obtaining a parameter data set; the parameter data set comprises N groups of calculation parameters, and each group of calculation parameters comprises a driver required torque and a target motor rotating speed; n is more than or equal to 2 and is an integer.
Specifically, the value range of the driver demand torque and the rotation speed range of the target motor (front axle motor or rear axle motor) can be determined according to a specific vehicle model, then a plurality of driver demand torque values are determined from the value range of the driver demand torque by taking 10 as compensation according to the value interval or value compensation, a plurality of target motor rotation speeds are determined from the target motor rotation speed range, then N groups of calculation parameters are formed according to the values, one driving working condition is corresponding to each group of calculation parameters, and the driving working condition comprises a specific value of the driver demand torque and a specific value of the target motor rotation speed.
S02: and carrying out operation according to each group of calculation parameters to obtain a target torque distribution coefficient corresponding to each group of calculation parameters. Comprising the following steps: for each group of calculation parameters, determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the target motor rotating speed, the driver demand torque and the plurality of candidate torque distribution coefficients; determining a candidate torque distribution coefficient corresponding to the total efficiency of a target driving system as the target torque distribution coefficient; the target drive system total efficiency is a drive system total efficiency that is not less than a set efficiency.
In the above scheme, the set efficiency may be a preset total efficiency of the driving system, or may be a total efficiency of all driving systems obtained under all the torque distribution coefficients to be selected according to the current working condition, that is, the current driver demand torque, the current target rotation speed, and then the maximum efficiency is taken from the total efficiency, or 90% -100% of the maximum efficiency is taken as the set efficiency. For example, when the maximum efficiency value is taken as the set efficiency, it indicates that the target torque distribution system is required to maximize the total efficiency of the current drive system of the host vehicle.
The candidate torque distribution coefficient may be determined according to a specified torque distribution coefficient selectable range. For example, the torque distribution coefficient is typically in the range of [0,1], and when 0 or 1 is used, a precursor or a postdrive is indicated. Then, a set of candidate torque distribution coefficients may be determined according to a preset value interval c, for example, 0.01, for example: 0,0.01,0.02, … …,0.99,1.0.
Meanwhile, for the limitation of peak torque of the front and rear shaft motors, when the torque allocated to the shaft is larger than the peak torque, the remaining torque in the required torque is allocated to the other shaft, so that the allocation result is the same under some allocation coefficient at different required torques.
Preferably, the candidate torque distribution coefficient is determined according to the target motor rotation speed and the driver demand torque, so that a candidate torque distribution coefficient range which is more matched with the current working condition of the vehicle can be determined, and the calculated amount is reduced, and the method specifically comprises the following steps:
determining a first peak torque of a front axle motor and a second peak torque of the rear axle motor according to the target motor rotating speed;
determining a value data set of a torque distribution coefficient according to the first peak torque and the second peak torque of the driver demand torque; the value data set comprises M torque distribution coefficients to be selected, wherein M is more than or equal to 2 and is an integer.
In particular, from the rotational speed-torque characteristic data provided by the drive motor supplier, the maximum torque that can be output at different rotational speeds of the motor, i.e., the peak torque, can be found. As described above, there is a correspondence between the rotational speed of the front-axle motor and the rotational speed of the rear-axle motor, and the peak torque of the corresponding target motor can be obtained by knowing the rotational speed of one of the motors.
Taking a front axle motor as a centralized motor and a rear axle motor as an in-wheel motor as an example, the method for determining the value data set of the torque distribution coefficient can be as follows:
And determining a torque distribution coefficient upper limit value according to the driver demand torque, the first peak torque and the front axle motor reduction ratio, wherein the torque distribution coefficient upper limit value is specifically as follows: obtaining a first calculated value; the first calculated value is determined from the product of the first peak torque and the front axle motor reduction ratio divided by the driver demand torque; obtaining a first value to be selected; the first value to be selected is determined according to the sum of the rounded first calculated value and the preset value interval; and determining the torque distribution coefficient upper limit value according to the minimum value between the first standby value and the first set value.
The first set value is a possible maximum value of the predetermined torque distribution coefficient, and may be 1,0.99,0.98 or the like.
Taking the first setting value equal to 1 as an example, the mathematical expression of the above scheme is as follows:
K max ＝min[1,roundn(T maxF ×η/T req )+c] (1)
in the above, K max For torque distribution coefficient upper limit value, min [ []Represents taking the minimum value, round () represents rounding, T maxF The first peak torque of the front axle motor is represented, eta is the reduction ratio of the front axle motor, and c is a preset value interval. The preset value interval is 0.01-0.05, and the value is usually 0.01 or 0.02.
Determining a torque distribution coefficient lower limit value according to the driver demand torque and the second peak torque; the method comprises the following steps: obtaining a second calculated value; the second calculated value is determined according to the difference value between the set value and the torque ratio; the torque ratio is determined from the second peak torque and the driver demand torque; obtaining a second value to be selected; the second value to be selected is determined according to the difference between the rounded second calculated value and the preset value interval; and determining the lower limit value of the torque distribution coefficient according to the maximum value between the second candidate value and the second set value.
The second set value is the smallest possible value of the predetermined torque distribution coefficient, and may be 0,0.01,0.02 or the like.
Taking the second set point equal to 0 as an example, the mathematical expression of the above scheme is as follows:
K min ＝max[0,roundn(1-2×T maxR /T req )-c] (2)
in the above, K min For torque distribution coefficient lower limit, max [ []Represents taking the maximum value, round () represents rounding, T maxR The second peak torque of the in-wheel motor is represented by multiplying by 2 because there are two in-wheel motors of the rear axle.
And determining the value data set according to the torque distribution coefficient lower limit value, the torque distribution coefficient upper limit value and a preset value interval.
After obtaining K min And K max Then, a series of torque distribution coefficient values can be obtained by combining the preset value interval c: k (K) min ，K min +c，K min +2c……，K max . These values will be used one by one in the subsequent calculations to calculate the overall efficiency of the drive system at different partition coefficients.
In the above process, a corresponding value data set of the torque distribution coefficient is determined according to each group of the driver demand torque and the target motor speed, and then the value data set and the current driving condition, that is, the torque distribution coefficient with the highest total efficiency of the driving system under the condition of the current driver demand torque and the current target motor speed are found.
The overall efficiency of the drive system is defined as the ratio of the useful power of the drive motor to the total power of the drive motor under drive conditions. The useful power is the actual output power of the driving motor, and the total power of the driving motor is the actual consumed power. The actual power consumption multiplied by the motor efficiency is the actual output power.
Thus, according to each set of driver demand torque T req An alternative scheme for determining the total efficiency of the corresponding drive system is as follows:
determining a front axle motor output torque and a rear axle motor output torque according to the candidate torque distribution coefficient and the driver demand torque;
specifically, the driver demand torque allocated by the front axle is K×T req Considering the action of the speed reducer, the front axle motor outputs torque M f ＝(K×T req ) And eta is the reduction ratio of the front axle motor. The driver demand torque distributed by the rear axle is (1-K) x T req If the hub motors are provided, the rear axle is provided with two hub motors, and the output torque M of each hub motor r ＝[(1-K)×T req ]/2。
Determining front axle motor efficiency according to the target motor speed, the front axle motor output torque and front axle motor efficiency characteristic data; determining rear axle motor efficiency according to the target motor speed, the rear axle motor output torque and the rear axle motor efficiency characteristic data;
Specifically, the efficiency characteristic data of the motor is motor system efficiency characteristic data tested and provided by a motor manufacturer, and after the motor rotating speed and the output torque are known, the corresponding motor efficiency can be directly inquired.
And determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the front axle motor efficiency, the rear axle motor efficiency, the front axle motor output torque, the rear axle motor output torque and the target motor rotating speed.
Thus, the overall efficiency of the drive system can be expressed as:
in the above formula: phi is the total efficiency of the driving system f For front axle motor efficiency, phi r For rear axle motor efficiency, M f Output torque for front axle motor, n f For the front axle motor speed, M r For the rear axle motor to output torque, n r The motor speed of the rear axle. As previously described, there is a fixed proportional relationship between front axle motor speed and rear axle motor speedTherefore, the rotation speed of the rear axle motor is obtained synchronously as long as the rotation speed of any one driving motor is obtained, for example, the rotation speed of the front axle motor is taken as the target rotation speed of the motor.
Alternatively, the torque T is demanded according to each group of drivers req The target motor rotation speed n and the candidate torque distribution coefficient K, another alternative scheme for determining the total efficiency of the corresponding driving system is as follows:
Determining a front axle motor output torque and a rear axle motor output torque according to the candidate torque distribution coefficient and the driver demand torque;
determining front axle motor efficiency according to the target motor speed, the front axle motor output torque and a front axle motor conversion coefficient; determining rear axle motor efficiency according to the target motor speed, the rear axle motor output torque and the rear axle motor conversion coefficient;
wherein, the front axle motor conversion coefficient l 1 The efficiency conversion coefficient corresponding to the current rotating speed and the current output torque of the front axle motor is as follows: phi (phi) f ＝l 1 ×M f ×n f The method comprises the steps of carrying out a first treatment on the surface of the Rear axle motor conversion coefficient l 2 The efficiency conversion coefficient corresponding to the current rotating speed and the current output torque of the rear axle motor is as follows: phi (phi) f ＝l 2 ×M r ×n r 。
And determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the front axle motor efficiency, the rear axle motor efficiency, the front axle motor output torque, the rear axle motor output torque and the target motor rotating speed.
By the scheme, any one group of driver demand torque T can be calculated req The target motor speed n and the total efficiency of the drive system at the candidate torque distribution coefficient K. Calculating the total efficiency of the driving system obtained by adopting different candidate torque distribution coefficients under the parameters of the current driver demand torque and the target motor speed through programming operation, comparing the total efficiency of all the driving systems, and using the candidate torque distribution coefficient with the highest total efficiency value of the driving system as the candidate torque distribution coefficient for matching the current driver demand torque and the target motor speed I.e. the target torque distribution coefficient.
And repeating the calculation process for each group of possible calculation parameters, namely the driver required torque and the target motor rotating speed of different combinations, so as to obtain the target torque distribution coefficient corresponding to each group of calculation parameters.
S03: and obtaining the mapping relation according to each group of calculation parameters and the target torque distribution coefficient corresponding to each group of calculation parameters.
After the target torque distribution coefficients under all possible driving working conditions are obtained, the result is made into a look-up table format and is applied to control strategy modeling, so that the aim of improving the total efficiency of a driving system can be achieved, the complexity of the control strategy modeling can be reduced, and the instantaneity of a control algorithm can be improved.
At present, three modes of a centralized motor, a hub motor and a hub motor exist in the arrangement of a driving motor of an electric automobile. Considering that the driving motor is arranged in the wheel hub motor driving, the four-wheel drive vehicle type purely based on the wheel hub motor has the advantages that the high-low voltage wire harness and the cooling pipeline of the motor are arranged at the wheel end, and when the four-wheel drive vehicle type purely based on the wheel hub motor is arranged on the front wheel, the wire harness and the pipeline take the steering and the jumping into consideration, so that a new challenge is provided for the inherently tense wheel end arrangement space. Therefore, the optimal mode of distributed driving based on the hub motor is that the front axle is driven in a centralized mode, and the rear wheel is driven by the hub motor, so that the distributed driving advantage can be reflected, the accurate active safety control of the vehicle and the high-quality driving experience are realized, and the influence of unsprung mass increase on a steering system and the complex wheel end arrangement are avoided.
Therefore, in order to more intuitively describe the torque distribution scheme provided by the present invention, in the following, a detailed description will be given by taking a distributed driving mode in which the front axle motor is a centralized motor and the rear axle motor is an in-wheel motor as an example, and after knowing the implementation of the present embodiment, those skilled in the art can use the same to multiplex the implementation modes into the implementation modes in which the front and rear are in-wheel motors, or both the front and rear are centralized motors.
Based on the inventive concept of the foregoing embodiment, in another alternative embodiment, the above scheme is applied to a vehicle controller of a certain electric vehicle type, the torque distribution control strategy is based on a distributed three-motor driving system of a hub motor, the front axle is driven by adopting a centralized motor, the rear axle is driven by adopting two hub motors, the front wheel driving motor transmits power to two front wheels through a speed reducer, a differential mechanism and a transmission shaft, the rear wheel hub motor is directly installed in a wheel, and the power directly acts on a wheel end. The structure of the electric system is schematically shown in fig. 3.
The whole control idea of the torque distribution control scheme is that the whole vehicle controller recognizes the driving intention of a driver according to the opening degree of an accelerator pedal and the current vehicle state, so that the current driving torque required by the driver is calculated, and the obtained generalized driving torque required by the driver is distributed to a centralized motor of a front shaft and two hubs of a rear shaft. The working points of the front and rear shaft motors are adjusted by adjusting the torque distribution coefficients of the front and rear shafts, and the aim of the highest total efficiency of a driving system is fulfilled, so that the optimized distribution of the longitudinal force required in a generalized manner is realized, and the economical efficiency of the vehicle is improved. The specific scheme is as follows:
1) And analyzing the torque required by the driver according to the opening degree of the accelerator pedal.
The linear accelerator pedal analysis is adopted, namely, the torque load coefficient of the motor and the opening degree of the accelerator pedal are in linear corresponding relation under the driving working condition, and the following formula is adopted:
L D ＝100％×Acc_Pedal (4)
in the above, L D In order to drive the motor torque load coefficient under the working condition, acc_Pedal is the opening degree of the acceleration Pedal.
Solving a motor torque load coefficient according to the opening degree of an accelerator pedal, and combining external characteristic data of a front axle concentrated motor and a rear axle hub motor to obtain the current driving force required by a driver in a generalized manner, namely the driving force required by the driver, wherein the driving force required by the driver is represented by the following formula:
T req ＝T req,1 ×η+T req,2 +T req,3 (6)
in the above, T req For the current driver demand torque, T req,i For each motor demand torque, T max,i For peak torque of each motor, n i For the current rotation speed of each motor, n b,i For each motor base speed, namely the rated rotation speed, eta is the front axle concentrated motor reduction ratio, and the value in the vehicle type of the embodiment is 6.294; i=1, 2,3. The peak torque can be obtained by querying motor speed-torque characteristic data based on the current motor speed.
2) A target (optimal) torque distribution coefficient is calculated.
The generalized demand torque obtained by solving is distributed to the centralized motor of the front axle and the two hub motors of the rear axle, and the torque distribution problem between the three motors can be converted into the torque distribution problem between the front axle and the rear axle in the running process of the vehicle because the rear wheels are provided with the two same hub motors.
In the present embodiment, the torque distribution coefficient K is defined as the ratio of the torque distributed to the front axle wheels to the total required torque, as shown in the following formula:
K＝T f /(T f +T r ) (7)
wherein the torque of the front and rear shaft motor meets T f +T r ＝T req ；T f T for torque distributed to front axle wheels r For torque distributed to the rear axle wheels.
According to the definition above, the torque T distributed to the front axle wheels f ＝K×T req In response to this distributed torque, the front axle concentrates the actual output torque M of the motor due to the influence of the speed reducer f ＝K×T req ×(1/η)。
Torque T distributed to rear axle wheels r ＝(1-K)×T req In response to the distributed torque, an actual output torque M of the hub motor r ＝(1-K)×T req /2。
The range of the torque distribution coefficient K should be [0,1], where 0 represents the rear drive, 1 represents the front drive, and in this embodiment, the interval c between the torque distribution coefficients is 0.01. And simultaneously, for the limitation of the peak torque of the front and rear shaft motors, when the torque distributed to the shaft is larger than the peak torque, the residual torque in the required torque is distributed to the other shaft.
Under the current driving working condition, the range of the torque distribution coefficient is as follows:
K min ＝max[0,roundn(1-2×T max,R /T req ,-2)-0.01] (8)
K max ＝min[1,roundn(T max,F ×η/T req ,-2)+0.01] (9)
in the above, K min For the lower limit value of the torque distribution coefficient, K max As torque distribution coefficient upper limit value, round (A, -2) is a rounding function, T max,F To concentrate the peak torque of the motor, T max,R The method is characterized in that the number A is rounded for the peak torque of the hub motor, and the number A is rounded to the decimal point and then two digits.
Next, according to the torque T distributed to the front axle f And the current rotation speed n of the concentrated motor f The front axle motor efficiency characteristic data (fig. 4, 5) provided by the supplier is queried to obtain front axle concentrated motor efficiencies. It should be noted that the torque transmission of the front axle concentrated motor needs to pass through the reducer with a reducer efficiency of 0.96, and thus the reducer efficiency is multiplied by the electric system efficiency value of the concentrated motor to obtain the final electric system efficiency phi of the concentrated motor f 。
Similarly, according to the torque T distributed to the rear axle r And the current rotational speed n of the hub motor r Querying in-wheel motor efficiency characteristic data (fig. 6, 7) provided by a supplier to obtain rear axle in-wheel motor efficiency phi r 。
As is known from the efficiency characteristics of the motor, the motor efficiency is related to the motor torque and the motor rotational speed, and at the current vehicle speed, if the torque distribution coefficients are different, the operating points of the front and rear shaft motors are different, and further, the respective motor efficiencies are different, so that the total efficiency of the drive system is also different. Therefore, the working points of the front and rear shaft motors can be adjusted by adjusting the torque distribution coefficient, and the aim of the highest total efficiency of the driving system is achieved, so that the optimal distribution of the longitudinal force of the generalized demand is realized.
Thus, under driving conditions, the overall efficiency of the drive system may be expressed as:
In the above, phi is the total efficiency of the drive system,to concentrate the motor at the actual output torqueThe rotation speed is n f Efficiency in time; />The actual output torque of the hub motor is +.>Rotational speed n r Efficiency, eta is the front axle centralized motor reduction ratio.
When slip rate is not considered, the front axle concentrates the motor rotation speed n f And the rotation speed n of the rear axle hub motor r The two exist between:thus equation (10) can be reduced to:
next, a data analysis software, such as Matlab, is used to program, by calculation, the torque distribution coefficient when the total efficiency of the drive system is highest, the current accelerator opening (indicative of the driver demand drive force), the current target motor speed. An alternative computational flow is shown in FIG. 8; t in the flow chart int Setting the initial value of the torque required by a driver to be 0, wherein n is the rotating speed of the hub motor (as the target rotating speed of the motor); n is n int Setting the initial value of the rotating speed of the hub motor to be 0; n is n max For the rotational speed of the hub motor6.294 is the front axle concentrated motor reduction ratio of the current vehicle model.
Step 1: initializing and setting 0;
step 2: judging whether the current rotation speed n is less than or equal to the maximum rotation speed n of the motor max If yes, go to step 3, otherwise end.
Step 3: let T int ＝T req And respectively calculating the highest torque T of the front motor and the rear motor according to the current motor rotation speed n max,F 、T max,R And total maximum torque T max,F +T max,R ；
Step 4: determining the required torque T req If the total maximum torque is smaller than or equal to the total maximum torque, the step 5 is carried out, otherwise, the motor rotating speed n is self-increased by 10, and the step 2 is carried out;
step 5: solving the rotation speed n and the required torque T req The torque distribution coefficient range at the time is obtained to obtain K min And K max Let k=k min ；
Step 6: judging whether K is less than or equal to K max If yes, go to step 7, otherwise, take the maximum value to all efficiency values stored, and compare (T req N, K) is stored (K at this time is the rotation speed n, the driver demand torque is T req Target (optimal) torque distribution coefficient at that time); next, T will be req 10, self-adding, and entering a step 3;
step 7: according to (T) req N, K), solving the total efficiency value phi of the driving system according to the motor efficiency MAP, adding K by 0.01, and entering a step 6.
Through the calculation, the optimal torque distribution coefficient under the combined condition of various driver required torques and hub motor rotating speeds under the driving working condition can be obtained. And then, the calculation result is made into a form of a lookup table and is applied to control strategy modeling, so that the aim of improving the total efficiency of the driving system can be fulfilled, the complexity of the control strategy modeling can be reduced, and the instantaneity of a control algorithm can be improved.
In general, the distributed three-motor driving system based on the hub motor in the embodiment aims at the highest total efficiency of the driving system under the condition of a certain total target driving torque, and the working points of the front and rear shaft motors are adjusted by adjusting the torque distribution coefficient, so that the torque optimal distribution of the longitudinal torque in a generalized demand is realized, the endurance mileage of the pure electric vehicle is improved under the condition that the electric quantity of a power battery is certain, and the economical efficiency of the vehicle is greatly improved.
Preferably, each hub motor is integrated with a motor controller, so that the layout space of the whole vehicle is greatly improved, a large number of wire harnesses are omitted, and the layout work is simplified.
Based on the same inventive concept as the previous embodiment, as shown in fig. 9, in yet another alternative embodiment, there is also provided a distributed torque distribution device of an electric vehicle, including:
an obtaining module 10, configured to obtain a current driver demand torque and a current rotation speed of a target motor during a running process of the host vehicle; the target motor is a front shaft motor or a rear shaft motor of the vehicle;
a determining module 20, configured to determine a target torque distribution coefficient according to the current rotation speed, the current driver demand torque, and a mapping relationship; the mapping relation is the corresponding relation between the motor rotating speed, the driver demand torque and the torque distribution coefficient; the target torque distribution coefficient is a torque distribution coefficient that satisfies a set condition for the total efficiency of the drive system of the host vehicle;
And the torque distribution module 30 is used for distributing the torque of the vehicle according to the target torque distribution coefficient and the current driver demand torque.
Optionally, the obtaining module 10 is configured to:
obtaining the opening of an acceleration pedal; and determining the current driver demand torque according to the opening degree of the acceleration pedal.
Optionally, the allocation device further includes a mapping relation determining module, configured to:
obtaining a parameter data set; the parameter data set comprises N groups of calculation parameters, and each group of calculation parameters comprises a driver required torque and a target motor rotating speed; n is more than or equal to 2 and is an integer;
calculating according to each set of calculation parameters to obtain target torque distribution coefficients corresponding to each set of calculation parameters, wherein the target torque distribution coefficients comprise: for each group of calculation parameters, determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the target motor rotating speed, the driver demand torque and the plurality of candidate torque distribution coefficients; determining a candidate torque distribution coefficient corresponding to the total efficiency of a target driving system as the target torque distribution coefficient; the target drive system total efficiency is a drive system total efficiency that is not less than a set efficiency;
And obtaining the mapping relation according to each group of calculation parameters and the target torque distribution coefficient corresponding to each group of calculation parameters.
Further, the mapping relation determining module is configured to:
determining a first peak torque of a front axle motor and a second peak torque of the rear axle motor according to the target motor rotating speed;
determining a value data set of a torque distribution coefficient according to the first peak torque and the second peak torque of the driver demand torque; the value data set comprises M torque distribution coefficients to be selected, wherein M is more than or equal to 2 and is an integer.
Further, when the front axle motor is a centralized motor and the rear axle motor is a hub motor, the mapping relation determining module is configured to:
the determining a value data set of a torque distribution coefficient according to the driver demand torque, the first peak torque and the second peak torque includes:
determining a torque distribution coefficient upper limit value according to the driver demand torque, the first peak torque and a front axle motor reduction ratio;
determining a torque distribution coefficient lower limit value according to the driver demand torque and the second peak torque;
And determining the value data set according to the torque distribution coefficient lower limit value, the torque distribution coefficient upper limit value and a preset value interval.
Further, the mapping relation determining module is configured to:
obtaining a first calculated value; the first calculated value is determined from the product of the first peak torque and the front axle motor reduction ratio divided by the driver demand torque;
obtaining a first value to be selected; the first value to be selected is determined according to the sum of the rounded first calculated value and the preset value interval;
and determining the torque distribution coefficient upper limit value according to the minimum value between the first standby value and the first set value.
Further, the mapping relation determining module is configured to:
obtaining a second calculated value; the second calculated value is determined according to the difference value between the set value and the torque ratio; the torque ratio is determined from the second peak torque and the driver demand torque;
obtaining a second value to be selected; the second value to be selected is determined according to the difference between the rounded second calculated value and the preset value interval;
and determining the lower limit value of the torque distribution coefficient according to the maximum value between the second candidate value and the second set value.
Further, the mapping relation determining module is configured to:
determining a front axle motor output torque and a rear axle motor output torque according to the candidate torque distribution coefficient and the driver demand torque;
determining front axle motor efficiency according to the target motor speed, the front axle motor output torque and front axle motor efficiency characteristic data;
determining rear axle motor efficiency according to the target motor speed, the rear axle motor output torque and the rear axle motor efficiency characteristic data;
and determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the front axle motor efficiency, the rear axle motor efficiency, the front axle motor output torque, the rear axle motor output torque and the target motor rotating speed.
According to the same inventive concept as the previous embodiments, in a further alternative embodiment, a vehicle control unit is provided, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the allocation method according to any of the previous embodiments when executing the computer program.
According to the same inventive concept as the previous embodiment, in yet another alternative embodiment, an electric vehicle is provided, which is characterized in that the electric vehicle includes the whole vehicle controller in the previous embodiment.
Through one or more embodiments of the present invention, the present invention has the following benefits or advantages:
the invention provides a distributed torque distribution method, a distributed torque distribution device and a whole vehicle controller of an electric vehicle, wherein in the running process of the electric vehicle, a target torque distribution coefficient matched with the current driving working condition is determined from the mapping relation between the motor rotation speed, the required torque and the torque distribution coefficient according to the current driving working condition, namely the required torque of a driver and the current rotation speed of a target motor; the target torque distribution coefficient is a distribution coefficient of front and rear axle torques which is preset and is used for enabling the total efficiency of the driving system to meet the set condition as a target under the current driving working condition; the setting condition may be that the total efficiency value of the driving system under the current working condition is the highest, or that the total efficiency value of the driving system under the current working condition is greater than the recommended efficiency value of the vehicle; in the running process, the working points of the front and rear shaft driving motors are adjusted by adopting the target torque distribution coefficient which enables the total efficiency of the driving system to be maintained at a higher level, so that the torque optimization distribution of the longitudinal torque in the generalized demand can be realized, the endurance mileage of the pure electric vehicle is improved under the condition that the electric quantity of the battery is fixed, and the energy economy of the electric vehicle is obviously improved.
On the other hand, the mapping relation is predetermined and applied to the torque distribution control strategy, so that the corresponding target torque distribution coefficient can be directly called under different driving working conditions, the aim of keeping the total efficiency of the driving system at a higher level can be achieved, the modeling complexity of the control strategy can be reduced, the real-time calculation workload is reduced, and the real-time performance of the torque distribution control under different driving working conditions is improved.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to cover such modifications and variations.

Claims (8)

1. A method for distributing distributed torque of an electric vehicle, the method comprising:
In the running process of the vehicle, the current driver demand torque and the current rotating speed of the target motor are obtained; the target motor is a front shaft motor or a rear shaft motor of the vehicle;
determining a target torque distribution coefficient according to the current rotating speed, the current driver demand torque and the mapping relation; the mapping relation is the corresponding relation between the motor rotating speed, the driver demand torque and the torque distribution coefficient; the target torque distribution coefficient is a torque distribution coefficient that satisfies a set condition for the total efficiency of the drive system of the host vehicle;
according to the target torque distribution coefficient and the current driver demand torque, the torque distribution of the vehicle is carried out;
the method for determining the mapping relation comprises the following steps:
obtaining a parameter data set; the parameter data set comprises N groups of calculation parameters, and each group of calculation parameters comprises a driver required torque and a target motor rotating speed; n is more than or equal to 2 and is an integer; calculating according to each set of calculation parameters to obtain target torque distribution coefficients corresponding to each set of calculation parameters, wherein the target torque distribution coefficients comprise: for each group of calculation parameters, determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the target motor rotating speed, the driver demand torque and the plurality of candidate torque distribution coefficients; determining a candidate torque distribution coefficient corresponding to the total efficiency of a target driving system as the target torque distribution coefficient; the target drive system total efficiency is a drive system total efficiency that is not less than a set efficiency; obtaining the mapping relation according to each group of calculation parameters and the target torque distribution coefficient corresponding to each group of calculation parameters;
The method for determining the candidate torque distribution coefficient comprises the following steps:
determining a first peak torque of a front axle motor and a second peak torque of the rear axle motor according to the target motor speed and the speed-torque characteristic data; and determining a value data set of the torque distribution coefficient according to the first peak torque and the second peak torque of the driver demand torque, wherein the value data set comprises M candidate torque distribution coefficients, and M is more than or equal to 2 and is an integer.
2. The dispensing method of claim 1 wherein said front axle motor is a concentrated motor and said rear axle motor is an in-wheel motor;
the determining a value data set of a torque distribution coefficient according to the driver demand torque, the first peak torque and the second peak torque includes:
determining a torque distribution coefficient upper limit value according to the driver demand torque, the first peak torque and a front axle motor reduction ratio;
determining a torque distribution coefficient lower limit value according to the driver demand torque and the second peak torque;
and determining the value data set according to the torque distribution coefficient lower limit value, the torque distribution coefficient upper limit value and a preset value interval.
3. The distribution method according to claim 2, wherein the determining of the torque distribution coefficient upper limit value from the first peak torque and the front axle motor reduction ratio according to the driver demand torque includes:
obtaining a first calculated value; the first calculated value is determined from the product of the first peak torque and the front axle motor reduction ratio divided by the driver demand torque;
obtaining a first value to be selected; the first value to be selected is determined according to the sum of the rounded first calculated value and the preset value interval;
and determining the torque distribution coefficient upper limit value according to the minimum value between the first standby value and the first set value.
4. The distribution method according to claim 2, wherein the determining a torque distribution coefficient lower limit value based on the driver demand torque and the second peak torque includes:
obtaining a second calculated value; the second calculated value is determined according to the difference value between the set value and the torque ratio; the torque ratio is determined from the second peak torque and the driver demand torque;
obtaining a second value to be selected; the second value to be selected is determined according to the difference between the rounded second calculated value and the preset value interval;
And determining the lower limit value of the torque distribution coefficient according to the maximum value between the second candidate value and the second set value.
5. The method of claim 1, wherein determining the overall efficiency of the drive system for each of the plurality of candidate torque split coefficients based on the target motor speed, the driver demand torque, and the plurality of candidate torque split coefficients comprises:
determining a front axle motor output torque and a rear axle motor output torque according to the candidate torque distribution coefficient and the driver demand torque;
determining front axle motor efficiency according to the target motor speed, the front axle motor output torque and front axle motor efficiency characteristic data;
determining rear axle motor efficiency according to the target motor speed, the rear axle motor output torque and the rear axle motor efficiency characteristic data;
and determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the front axle motor efficiency, the rear axle motor efficiency, the front axle motor output torque, the rear axle motor output torque and the target motor rotating speed.
6. A distributed torque distribution device for an electric vehicle, the distribution device comprising:
The obtaining module is used for obtaining the current driver demand torque and the current rotating speed of the target motor in the running process of the vehicle; the target motor is a front shaft motor or a rear shaft motor of the vehicle;
the determining module is used for determining a target torque distribution coefficient according to the current rotating speed, the current driver demand torque and the mapping relation; the mapping relation is the corresponding relation between the motor rotating speed, the driver demand torque and the torque distribution coefficient; the target torque distribution coefficient is a torque distribution coefficient that satisfies a set condition for the total efficiency of the drive system of the host vehicle;
the torque distribution module is used for distributing the torque of the vehicle according to the target torque distribution coefficient and the current driver demand torque;
the method for determining the mapping relation comprises the following steps:
obtaining a parameter data set; the parameter data set comprises N groups of calculation parameters, and each group of calculation parameters comprises a driver required torque and a target motor rotating speed; n is more than or equal to 2 and is an integer; calculating according to each set of calculation parameters to obtain target torque distribution coefficients corresponding to each set of calculation parameters, wherein the target torque distribution coefficients comprise: for each group of calculation parameters, determining the total efficiency of the driving system corresponding to each candidate torque distribution coefficient according to the target motor rotating speed, the driver demand torque and the plurality of candidate torque distribution coefficients; determining a candidate torque distribution coefficient corresponding to the total efficiency of a target driving system as the target torque distribution coefficient; the target drive system total efficiency is a drive system total efficiency that is not less than a set efficiency; obtaining the mapping relation according to each group of calculation parameters and the target torque distribution coefficient corresponding to each group of calculation parameters;
The method for determining the candidate torque distribution coefficient comprises the following steps:
determining a first peak torque of a front axle motor and a second peak torque of the rear axle motor according to the target motor speed and the speed-torque characteristic data; and determining a value data set of the torque distribution coefficient according to the first peak torque and the second peak torque of the driver demand torque, wherein the value data set comprises M candidate torque distribution coefficients, and M is more than or equal to 2 and is an integer.
7. A vehicle control unit comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the allocation method according to any one of claims 1 to 5 when executing the computer program.
8. An electric vehicle, characterized in that it comprises a complete vehicle controller according to claim 7.
CN202111064498.4A 2021-09-10 2021-09-10 Electric automobile and distributed torque distribution method and device thereof Active CN113829891B (en)

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