CN112477627A

CN112477627A - Python-based pure electric vehicle torque distribution coefficient analysis method and system

Info

Publication number: CN112477627A
Application number: CN202011387653.1A
Authority: CN
Inventors: 白志浩; 赵征澜; 佘建强; 张丽; 徐飞
Original assignee: Dongfeng Motor Corp
Current assignee: Dongfeng Motor Corp
Priority date: 2020-12-01
Filing date: 2020-12-01
Publication date: 2021-03-12
Anticipated expiration: 2040-12-01
Also published as: CN112477627B

Abstract

The invention discloses a Python-based pure electric vehicle torque distribution coefficient analysis method and system, and relates to the field of electric vehicles, wherein the method comprises the following steps: reading the external characteristic data of the front motor and the external characteristic data of the rear motor through a Python third-party library openpyxl module, and generating working condition points of each vehicle according to a preset sampling rule; acquiring the motor efficiency before sampling points and the motor efficiency after sampling points; interpolating according to the motor efficiency before sampling points and the motor efficiency after sampling points by a Python third-party library numpy module, a math module, a scipy module and a panda module to obtain the motor efficiency before non-sampling points and the motor efficiency after non-sampling points in each vehicle working condition point; and analyzing the optimal torque distribution coefficient of each vehicle working condition point according to the front motor efficiency and the rear motor efficiency. The invention distributes the torque of the front motor and the rear motor, can ensure that the efficiency of a vehicle power system is always kept optimal when the vehicle dynamic requirement is met, reduces the energy consumption of the vehicle and improves the driving range of the vehicle.

Description

Python-based pure electric vehicle torque distribution coefficient analysis method and system

Technical Field

The invention relates to the field of analysis, in particular to a Python-based pure electric vehicle torque distribution coefficient analysis method and system.

Background

In the new energy automobile market at present, pure electric vehicles driving mode is mostly two drives, and the vehicle that drives four is taken up than less, compares with two drives four and drives the whole adhesive force of utilization vehicle that can furthest, can show the vehicle dynamic nature that promotes. However, because a set of power system is added to the four-wheel drive vehicle compared with the two-wheel drive vehicle, the four-wheel drive vehicle has a significantly heavier weight than the two-wheel drive vehicle, and the vehicle resistance is increased while the adhesion force of the four-wheel drive vehicle is increased due to the heavy weight, so that the energy consumption of the four-wheel drive vehicle is correspondingly increased. The energy consumption of the vehicle mainly comprises overcoming the resistance loss of the vehicle and the loss of a vehicle power system, and the energy consumption of the vehicle can be reduced by reducing the loss of the vehicle power system. Vehicle powertrain losses can be reduced by ensuring powertrain efficiency is optimal. At present, the torque of motors of a pure electric vehicle before and after four-wheel drive is distributed according to a fixed proportion, and a real-time working condition is not combined, so that the system optimization cannot be achieved.

Disclosure of Invention

The invention aims to overcome the defects of the background art, and provides a Python-based pure electric vehicle torque distribution coefficient analysis method and system, which are used for distributing the torque of front and rear motors, can ensure that the efficiency of a vehicle power system is kept optimal all the time when the vehicle dynamic demand is met, reduce the vehicle energy consumption and improve the vehicle driving range

In a first aspect, a Python-based pure electric vehicle torque distribution coefficient analysis method is provided, and includes the following steps:

reading the external characteristic data of the front motor and the external characteristic data of the rear motor through a Python third-party library openpyxl module, and generating working condition points of each vehicle according to a preset sampling rule;

acquiring the motor efficiency before and after sampling points, wherein the sampling points are any more than one of the vehicle working condition points;

interpolating to obtain the non-sampling point front motor efficiency and the non-sampling point rear motor efficiency in each vehicle working condition point according to the sampling point front motor efficiency and the sampling point rear motor efficiency through a Python third party library numpy module, a math module, a scipy module and a panda module;

and analyzing the optimal torque distribution coefficient of each vehicle working condition point according to the front motor efficiency and the rear motor efficiency, wherein the front motor efficiency comprises the sampling point front motor efficiency and the non-sampling point front motor efficiency, and the rear motor efficiency comprises the sampling point rear motor efficiency and the non-sampling point rear motor efficiency.

According to the first aspect, in a first possible implementation manner of the first aspect, the step of reading the external characteristic data of the front motor and the external characteristic data of the rear motor through a Python third-party library openpyxl module and generating the working points of the vehicle according to a preset sampling rule includes the following steps:

reading the external characteristic data of the front motor and the external characteristic data of the rear motor;

respectively determining the maximum rotating speed of a front motor, the maximum rotating speed of a rear motor, the maximum torque of the front motor at any rotating speed and the maximum torque of the rear motor at any rotating speed according to the external characteristic data of the front motor and the external characteristic data of the rear motor, selecting the smaller value of the maximum rotating speed of the front motor and the maximum rotating speed of the rear motor as the maximum rotating speed of a power system, and selecting the maximum torque of the front motor and the maximum torque of the rear motor at any rotating speed as the maximum torque of the power system at any rotating speed; and generating each vehicle working condition point by combining the maximum rotating speed of the power system and the maximum torque of the power system according to a preset sampling rule, wherein the vehicle working condition points comprise the rotating speed of the motor and the corresponding torque of the power system.

According to the first aspect, in a second possible implementation manner of the first aspect, before the step of analyzing the optimal torque distribution coefficient of each vehicle operating point according to a front motor efficiency and a rear motor efficiency, where the front motor efficiency includes the sampling point front motor efficiency and the non-sampling point front motor efficiency, and the rear motor efficiency includes the sampling point rear motor efficiency and the non-sampling point rear motor efficiency, the method specifically includes the following steps:

selecting any target vehicle working condition point, and acquiring a target power system torque of the target vehicle working condition point;

if the target power system torque is less than or equal to a first torque value T₁Then the torque distribution coefficient range for the target vehicle operating point is set to [0,1]]The first torque value is the smaller value of the maximum torque of the front motor and the maximum torque of the rear motor at the target rotating speed;

if the target power system torque is larger than the first torque value T₁And is less than or equal to the second torque value T₂Then the torque distribution coefficient range for the target vehicle operating point is set to

The second torque value is the larger value of the maximum torque of the front motor and the maximum torque of the rear motor at the target rotating speed;

if the target power system torque is larger than a second torque value T₂Then the torque distribution coefficient range for the target vehicle operating point is set to

According to the second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, the step of analyzing the optimal torque distribution coefficient of each vehicle operating point according to a front motor efficiency and a rear motor efficiency, where the front motor efficiency includes the sampling point front motor efficiency and the non-sampling point front motor efficiency, and the rear motor efficiency includes the sampling point rear motor efficiency and the non-sampling point rear motor efficiency, specifically includes the following steps:

a plurality of groups of efficiency ratio pairs are set in the torque distribution coefficient range, and the efficiency ratio pairs subdivide the target power system torque into corresponding target front motor torque and target rear motor torque according to different torque distribution coefficients;

determining corresponding target front motor efficiency according to the target rotating speed of the target vehicle working condition point and the target front motor torque, and determining corresponding target rear motor efficiency according to the target rotating speed of the target vehicle working condition point and the target rear motor torque;

acquiring the efficiency of a front speed reducer and the efficiency of a rear speed reducer;

analyzing the efficiency of the power system of each efficiency ratio pair group according to the target front motor torque, the target rear motor torque, the target front motor efficiency, the target rear motor efficiency, the front speed reducer efficiency and the rear speed reducer efficiency;

and determining the optimal torque distribution coefficient according to the power system efficiency.

According to a third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, the step of analyzing the powertrain efficiency of each efficiency ratio pair group according to the target front motor torque, the target rear motor torque, the target front motor efficiency, the target rear motor efficiency, the front retarder efficiency, and the rear retarder efficiency specifically includes the following steps:

obtaining the output power P of the front motor according to the target front motor torque₀₁Obtaining the output power P of the rear motor according to the target rear motor torque₀₂；

According to the target front motor efficiency eta₁And the output power P of the front motor₀₁Motor input power P before calculation₁₁，

According to the target rear motor efficiency eta₂And the output power P of the rear motor₀₂Calculated motor input power P₁₂，

According to the output power P of the front motor₀₁The output power P of the rear motor₀₂The input power P of the front motor₁₁The input power P of the rear motor₁₂Efficiency eta of the front speed reducer₃And said rear retarder efficiency eta₄Analyzing the efficiency eta of the power system of each efficiency ratio pair group，

In a second aspect, a pure electric vehicle torque distribution coefficient analysis system based on Python is provided, including:

the data reading and processing module is used for reading the external characteristic data of the front motor and the external characteristic data of the rear motor through a Python third-party library openpyxl module, generating each vehicle working condition point according to a preset sampling rule, and acquiring the motor efficiency before sampling points and the motor efficiency after sampling points, wherein the sampling points are any number of the vehicle working condition points;

the operating point efficiency analysis module is in communication connection with the data reading and processing module and is used for interpolating to obtain the non-sampling point front motor efficiency and the non-sampling point rear motor efficiency in each vehicle operating point according to the sampling point front motor efficiency and the sampling point rear motor efficiency through a Python third-party library numpy module, a math module, a scipy module and a panda module; and the number of the first and second groups,

and the optimal distribution coefficient calculation module is in communication connection with the operating point efficiency analysis module and is used for analyzing the optimal torque distribution coefficient of each vehicle operating point according to the front motor efficiency and the rear motor efficiency, the front motor efficiency comprises the sampling point front motor efficiency and the non-sampling point front motor efficiency, and the rear motor efficiency comprises the sampling point rear motor efficiency and the non-sampling point rear motor efficiency.

According to the second aspect, in a first possible implementation manner of the second aspect, the data reading processing module includes:

the data reading unit is used for reading the external characteristic data of the front motor and the external characteristic data of the rear motor;

the data processing unit is in communication connection with the data reading unit and is used for respectively determining the maximum rotating speed of a front motor, the maximum rotating speed of a rear motor, the maximum torque of the front motor at any rotating speed and the maximum torque of the rear motor at any rotating speed according to the external characteristic data of the front motor and the external characteristic data of the rear motor, selecting the smaller value of the maximum rotating speed of the front motor and the maximum rotating speed of the rear motor as the maximum rotating speed of a power system, and selecting the maximum torque of the front motor and the maximum torque of the rear motor at any rotating speed as the maximum torque of the power system at any rotating speed; generating each vehicle working condition point by combining the maximum rotating speed of the power system and the maximum torque of the power system according to a preset sampling rule, wherein the vehicle working condition points comprise the rotating speed of a motor and the corresponding torque of the power system;

and the data acquisition unit is in communication connection with the data processing unit and is used for acquiring the motor efficiency before sampling points and the motor efficiency after sampling points, and the sampling points are any more than one of the vehicle working condition points.

According to a second aspect, in a second possible implementation manner of the second aspect, the system further includes:

a torque distribution constraint module, communicatively coupled to the operating point efficiency analysis module, to:

In a third possible implementation manner of the second aspect, the optimal distribution coefficient calculating module is connected to the torque distribution constraint module in a communication manner, and includes:

the grouping unit is used for setting a plurality of groups of efficiency ratio groups in the torque distribution coefficient range, and the efficiency ratio groups subdivide the target power system torque into corresponding target front motor torque and target rear motor torque according to different torque distribution coefficients;

the motor efficiency analysis unit is in communication connection with the grouping unit and is used for determining corresponding target front motor efficiency according to the target rotating speed of the target vehicle working condition point and the target front motor torque and determining corresponding target rear motor efficiency according to the target rotating speed of the target vehicle working condition point and the target rear motor torque;

an efficiency obtaining unit for obtaining a front reducer efficiency and a rear reducer efficiency;

the system efficiency analysis unit is in communication connection with the motor efficiency analysis unit and the efficiency acquisition unit and is used for analyzing the power system efficiency of each efficiency ratio pair group according to the target front motor torque, the target rear motor torque, the target front motor efficiency, the target rear motor efficiency, the front speed reducer efficiency and the rear speed reducer efficiency;

and the optimal coefficient analysis unit is in communication connection with the system efficiency analysis unit and is used for determining the optimal torque distribution coefficient according to the power system efficiency.

According to a third possible implementation manner of the second aspect, in a fourth possible implementation manner of the second aspect, the system efficiency analysis unit includes:

an input power analysis subunit for obtaining the output power P of the front motor according to the target front motor torque₀₁Obtaining the output power P of the rear motor according to the target rear motor torque₀₂；

An output power analyzing subunit, communicatively coupled to the input power analyzing subunit, for analyzing the output power based on the output powerTarget front motor efficiency η₁And the output power P of the front motor₀₁Motor input power P before calculation₁₁，

A system efficiency analysis subunit, communicatively connected to the input power analysis subunit and the output power analysis subunit, for analyzing the output power P of the front motor₀₁The output power P of the rear motor₀₂The input power P of the front motor₁₁The input power P of the rear motor₁₂Efficiency eta of the front speed reducer₃And said rear retarder efficiency eta₄Analyzing the efficiency eta of the power system of each efficiency ratio pair group,

compared with the prior art, the method uses the python language for calculating the torque distribution coefficients of the front motor and the rear motor, finds out the optimal distribution coefficient of the efficiency of the vehicle power system under all working points, so that the optimal distribution coefficient forms a distribution coefficient table, the distribution coefficient table can be inquired in real time during the torque control process of the vehicle under the four-wheel drive mode, the torque distribution can be carried out on the front motor and the rear motor, the efficiency of the vehicle power system can be kept optimal constantly when the dynamic requirement of the vehicle is met, the energy consumption of the vehicle is reduced, and the driving range of the vehicle is increased.

Drawings

FIG. 1 is a schematic flowchart of an embodiment of a Python-based pure electric vehicle torque distribution coefficient analysis method according to the present invention;

FIG. 2 is a schematic flowchart of another embodiment of a Python-based pure electric vehicle torque distribution coefficient analysis method according to the present invention;

FIG. 3 is a schematic flowchart of another embodiment of a Python-based pure electric vehicle torque distribution coefficient analysis method according to the present invention;

fig. 4 is a schematic structural diagram of an embodiment of a pure electric vehicle torque distribution coefficient analysis system based on Python according to the present invention.

Reference numerals:

100. a Python-based pure electric vehicle torque distribution coefficient analysis system; 110. a data reading processing module; 111. a data reading unit; 112. a data processing unit; 113. a data acquisition unit; 120. a working point efficiency analysis module; 130. an optimal distribution coefficient calculation module; 131. a grouping unit; 132. a motor efficiency analysis unit; 133. an efficiency acquisition unit; 134. a system efficiency analysis unit; 135. an optimum coefficient analysis unit; 140. a torque distribution constraint module.

Detailed Description

Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the specific embodiments, it will be understood that they are not intended to limit the invention to the embodiments described. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. It should be noted that the method steps described herein may be implemented by any functional block or functional arrangement, and that any functional block or functional arrangement may be implemented as a physical entity or a logical entity, or a combination of both.

In order that those skilled in the art will better understand the present invention, the following detailed description of the invention is provided in conjunction with the accompanying drawings and the detailed description of the invention.

Note that: the example to be described next is only a specific example, and does not limit the embodiments of the present invention necessarily to the following specific steps, values, conditions, data, orders, and the like. Those skilled in the art can, upon reading this specification, utilize the concepts of the present invention to construct more embodiments than those specifically described herein.

Referring to fig. 1, an embodiment of the present invention provides a pure electric vehicle torque distribution coefficient analysis method based on Python, including the following steps:

acquiring the motor efficiency before and after sampling points, wherein the sampling points are any more than one vehicle working condition points;

interpolating according to the motor efficiency before sampling points and the motor efficiency after sampling points by a Python third-party library numpy module, a math module, a scipy module and a panda module to obtain the motor efficiency before non-sampling points and the motor efficiency after non-sampling points in each vehicle working condition point;

and analyzing the optimal torque distribution coefficient of each vehicle working condition point according to the front motor efficiency and the rear motor efficiency, wherein the front motor efficiency comprises the front motor efficiency of the sampling point and the front motor efficiency of the non-sampling point, and the rear motor efficiency comprises the rear motor efficiency of the sampling point and the rear motor efficiency of the non-sampling point.

Specifically, in this embodiment, the Python third-party library openpyxl module is used for reading the external characteristic data of the front motor and the external characteristic data of the rear motor, generating each vehicle operating point according to a preset sampling rule, and setting the value steps of the rotating speed and the torque in each vehicle operating point, wherein the step values are set based on the parameters and the operating characteristics of the motors or are set autonomously according to needs.

Selecting a plurality of working condition points in the vehicle working condition points as sampling points, acquiring the motor efficiency before the sampling points and the motor efficiency after the sampling points, wherein the motor efficiency before the sampling points and the motor efficiency after the sampling points are the efficiencies of a front motor and a rear motor which are actually measured under the working condition of the sampling points. The sampling points are any number of vehicle working condition points, the values of the torques distributed to the front motor and the rear motor in the sampling points are uniquely determined, namely the rotating speed and the torque value of the front motor in the sampling points are determined values, the rotating speed and the torque value of the rear motor are also determined values, and the efficiencies of the front motor and the rear motor are also uniquely determined values under the condition.

Through a Python third-party library numpy module, a math module, a scipy module and a panda module, according to the motor efficiency before sampling points and the motor efficiency after sampling points, interpolation is carried out to obtain the motor efficiency before non-sampling points and the motor efficiency after non-sampling points in each vehicle working condition point, and the interpolation method adopts a 'nearest value-taking method'. The rotating speed, the torque and the efficiency of the sampling point are known, and the corresponding efficiency is obtained by combining the rotating speed and the torque of the non-sampling point.

The efficiency of the power system under different distribution coefficients of each vehicle working condition point is analyzed according to all the front motor efficiency and the rear motor efficiency under different rotating speeds and torques, so that the optimal torque distribution coefficient of each vehicle working condition point is obtained, the front motor efficiency comprises the front motor efficiency of a sampling point and the front motor efficiency of a non-sampling point, and the rear motor efficiency comprises the rear motor efficiency of the sampling point and the rear motor efficiency of the non-sampling point.

And generating an optimal torque distribution coefficient table by the optimal torque distribution coefficient of each vehicle operating point, finding corresponding matched vehicle operating points according to the motor rotating speed and the required torque of the vehicle in the subsequent vehicle running process, and selecting the corresponding optimal torque distribution coefficient to perform torque distribution on the front motor and the rear motor so as to obtain the optimal torque distribution result of the current condition.

The motor torque distribution coefficient calculation method based on the Python language uses the Python language to compile script files to calculate the motor torque distribution coefficient before and after the optimal efficiency of the vehicle power system. The Python language is a high-level script language which combines the interpretability, the compiling performance, the interactivity and the object-oriented performance, has strong readability, is easy to learn and read, and in addition, the Python language has rich third party libraries which can assist in processing various works, wherein the Python language is particularly simple and convenient to use in the aspects of scientific calculation and big data processing. The Python language is used for calculating the motor torque distribution coefficient before and after the optimal efficiency of the vehicle power system, and the effects of simplicity, convenience and quickness can be achieved.

Optionally, in another embodiment of the present application, the step of "reading, by using a Python third party library openpyxl module, the external characteristic data of the front motor and the external characteristic data of the rear motor, and generating the operating points of the vehicles according to a preset sampling rule" specifically includes the following steps:

respectively determining the maximum rotating speed of the front motor, the maximum rotating speed of the rear motor, the maximum torque of the front motor at any rotating speed and the maximum torque of the rear motor at any rotating speed according to the external characteristic data of the front motor and the external characteristic data of the rear motor, selecting the smaller value of the maximum rotating speed of the front motor and the maximum rotating speed of the rear motor as the maximum rotating speed of the power system, and selecting the maximum torque of the front motor and the maximum torque of the rear motor at any rotating speed as the maximum torque of the power system at any rotating speed; and generating each vehicle operating point by combining the maximum rotating speed of the power system and the maximum torque of the power system according to a preset sampling rule, wherein the vehicle operating points comprise the rotating speed of the motor and the corresponding torque of the power system.

Specifically, in this embodiment, the external characteristic data of the front motor and the external characteristic data of the rear motor are read, and according to the actually measured external characteristic data of the front motor and the rear motor, the rotation speed range of the front motor and the torque range corresponding to the specific rotation speed are determined, and the rotation speed range of the rear motor and the torque range corresponding to the specific rotation speed are determined. And calculating the rotating speed range of the vehicle power system and the torque range corresponding to the specific rotating speed according to the clear rotating speed ranges of the front motor and the rear motor and the torque range corresponding to the specific rotating speed, wherein the vehicle power system comprises a front motor acceleration and deceleration system and a rear motor acceleration and deceleration system. And designing a vehicle working condition point (rotating speed-torque) according to the clear rotating speed range of the vehicle power system and the torque range corresponding to the specific rotating speed. For example, the partitioning principle (for ease of understanding, the following are not limited to be used) is as follows:

a) the rotating speed takes 500rpm as the initial rotating speed, takes the highest rotating speed as the final rotating speed, and takes 500rpm as the gradient to obtain the rotating speed working point in the full rotating speed range.

b) And (c) selecting a certain rotating speed working condition point in the step a, wherein the torque takes 10Nm as an initial torque, the maximum torque of the current rotating speed as a termination torque, and the 10Nm as a gradient to obtain all torque working condition points under the current rotating speed.

c) And (c) repeating the step (b) to obtain torque working condition points under all the rotating speeds, and further obtain all the torque distribution coefficient calculation working condition points.

The method includes the steps that external characteristic data of a front motor and a rear motor are imported, and the maximum value of the rotating speed of a power system and the rotating speed range of a vehicle power system are determined; the working condition point of the vehicle is designed more reasonably according to the rotating speed range of the vehicle power system and the maximum torque of the front motor and the rear motor at specific rotating speeds.

Optionally, as shown in fig. 2, in another embodiment of the present application, before the step of "analyzing the optimal torque distribution coefficient of each vehicle operating point according to a front motor efficiency and a rear motor efficiency, the front motor efficiency includes a sampling point front motor efficiency and a non-sampling point front motor efficiency, and the rear motor efficiency includes a sampling point rear motor efficiency and a non-sampling point rear motor efficiency", the method specifically includes the following steps:

if the target power system torque is less than or equal to the first torque value T₁Then the torque distribution coefficient range for the target vehicle operating point is set to [0,1]]The first torque value is the smaller value of the maximum torque of the front motor and the maximum torque of the rear motor at the target rotating speed;

if the target power system torque is larger than the second torque value T₂Then the torque distribution coefficient range for the target vehicle operating point is set to

Specifically, in this embodiment, any target vehicle operating point is selected, the target power system torque of the target vehicle operating point is obtained, that is, the target rotating speed and the target power system torque at the target vehicle operating point are selected, and the torque distribution coefficient range of the target vehicle operating point is obtained by comparing the maximum torque of the front motor and the maximum torque of the rear motor at the target rotating speed. Therefore, when the distribution coefficient range is restricted, the method is simpler, and the selected range can cover all values meeting the requirements.

Optionally, in another embodiment of the present application, the step of "analyzing the optimal torque distribution coefficient of each vehicle operating point according to a front motor efficiency and a rear motor efficiency, where the front motor efficiency includes a sampling point front motor efficiency and a non-sampling point front motor efficiency, and the rear motor efficiency includes a sampling point rear motor efficiency and a non-sampling point rear motor efficiency" specifically includes the following steps:

a plurality of groups of efficiency ratio pairs are set in the torque distribution coefficient range, and the target power system torque is subdivided into corresponding target front motor torque and target rear motor torque according to different torque distribution coefficients in the efficiency ratio pairs;

determining corresponding target front motor efficiency according to the target rotating speed and the target front motor torque of the target vehicle working condition point, and determining corresponding target rear motor efficiency according to the target rotating speed and the target rear motor torque of the target vehicle working condition point;

and determining an optimal torque distribution coefficient according to the efficiency of the power system.

Specifically, in this embodiment, each vehicle operating point is only provided with the rotation speed and the corresponding powertrain torque, and the powertrain torque is not specifically distributed to the front motor and the rear motor. Therefore, for each vehicle working condition point, a plurality of groups of efficiency ratio pairs are set in the torque distribution coefficient range, the torque of the power system is respectively distributed to the front motor and the rear motor in each group of efficiency ratio pairs according to a certain torque distribution coefficient, that is, the rotating speeds and torques of the front motor and the rear motor in each group of efficiency ratio pairs are determined, so that the efficiency of the front motor at the sampling point, the efficiency of the rear motor at the sampling point, the efficiency of the front motor at the non-sampling point and the efficiency of the rear motor at the non-sampling point in the description of the embodiment can determine the efficiency of the front motor at the target in each group of efficiency ratio pairs and the efficiency. Wherein, the variation steps of the torque distribution coefficients among the efficiency ratio pair groups can be set according to different requirements, for example, the variation gradient of the torque distribution coefficients is set to be 0.01.

Since the vehicle power system includes a front motor acceleration and deceleration system and a rear motor deceleration system, that is, the efficiency of the decelerator affects the vehicle power system, the efficiency of the front decelerator and the efficiency of the rear decelerator are obtained.

And analyzing the efficiency of the power system of each efficiency ratio pair group according to the target front motor torque, the target rear motor torque, the target front motor efficiency, the target rear motor efficiency, the front speed reducer efficiency and the rear speed reducer efficiency. And comparing the efficiencies of the power systems of the efficiency ratio pair groups, and selecting the torque distribution coefficient corresponding to the efficiency ratio pair group with the highest efficiency as the optimal torque distribution coefficient.

The method and the device set the efficiency ratio of the multiple groups of torque distribution coefficients to step change to calculate the efficiency of the power system of the group respectively so as to select the optimal torque distribution coefficient more comprehensively.

Optionally, in another embodiment of the present application, the step of "analyzing the powertrain efficiency of each efficiency ratio pair group according to the target front motor torque, the target rear motor torque, the target front motor efficiency, the target rear motor efficiency, the front retarder efficiency, and the rear retarder efficiency" specifically includes the following steps:

According to the output power P of the front motor₀₁The output power P of the rear motor₀₂The input power P of the front motor₁₁The input power P of the rear motor₁₂Efficiency eta of the front speed reducer₃And said rear retarder efficiency eta₄Analyzing the efficiency eta of the power system of each efficiency ratio pair group,

specifically, in this embodiment, the corresponding power value can be directly calculated according to the torque value, and the target front motor torque and the target rear motor torque are both torque values required to be output by the motor, so that the front motor output power P is obtained according to the target front motor torque₀₁Obtaining a post-motor output power P according to the target post-motor torque₀₂The output power of the front motor and the output power of the rear motor under the working condition of the vehicle under the torque distribution coefficient of the efficiency comparison group are obtained through calculation, and the front motor efficiency and the rear motor efficiency are fixed and obtained due to the fact that the rotating speed and the torque are fixed, so that the front motor efficiency eta is obtained according to the target₁And front motor output power P₀₁Motor input power P before calculation₁₁，

According to target rear motor efficiency eta₂And the output power P of the rear motor₀₂Calculated motor input power P₁₂，

Finally, according to the output power P of the front motor₀₁Rear motor output power P₀₂Front motor input power P₁₁Rear motor input power P₁₂Front retarder efficiency eta₃And rear retarder efficiency η₄Analyzing the efficiency eta of the power system of each efficiency ratio pair group,

the invention writes a script program for calculating the motor torque distribution coefficient before and after the optimal efficiency of the vehicle power system by relying on the embodiment as follows:

s1, importing front and rear motor external characteristic data, wherein the front motor external characteristic data is shown in a first table, and the rear motor external characteristic data is shown in a second table;

motor external characteristic data before table one

Rotating speed (r/min)	Torque (Nm)
		500	232
1000	233
		1500	235
…	…
		12500	91

Motor external characteristic data after table two

Rotating speed (r/min)	Torque (Nm)
		500	308
1000	305
		1500	305
…	…
		16000	88

According to the external characteristic data of the front and rear motors, the speed ratio of the front and rear speed reducers is set to be consistent with that of the front and rear speed reducers, so that the maximum value Nmax of the rotating speed of the power system is set to be min (Nmax _ f, Nmax _ r) to be 12500, and the rotating speed range of the power system of the vehicle is 0-12500.

S2, according to the rotating speed range of the vehicle power system and the maximum torque Tmax _ n at the specific rotating speeds of the front motor and the rear motor, wherein n is 500,1000,1500 500,1000,1500 … 12500, the working point of the designed vehicle is as shown in the third table:

meter three vehicle operating points

Rotating speed (r/min)	Torque (Nm)
		500	10
500	20
		500	30
…
		500	540
1000	10
		…	…
12500	198

S3, calculating the torque distribution coefficient of the front and rear motors which enables the efficiency of the vehicle power system to be optimal at each working condition point, according to the torque distribution coefficient calculation method provided by the invention, the relationship between the torque value at the working condition point and the maximum torque of the front and rear motors at the rotating speed corresponding to the working condition point is firstly compared. If T _ n < T _ max _ f _ n and T _ n < T _ max _ r _ n, the range of the torque distribution coefficients of the front and rear motors is limited to [0,1], and the condition judgment is realized by the following statements:

iffloat(ws.cell(row＝i,column＝2).value)/Torque_max_90<1:

proportions＝list(range(0,101,1))

in the present embodiment, the maximum torque of the rear motor is always greater than the maximum torque of the front motor at the same rotation speed, so only the magnitude relationship between T _ n and T _ max _ f _ n is determined.

If T _ n > T _ max _ f _ n andT _ n < T _ max _ r _ n, then the front and rear motor torque distribution coefficient ranges are defined as [0, T _ max _ f _ n/Tmax _ n ], the conditional determination is achieved by:

elif float(ws.cell(row＝i,column＝2).value)/Torque_max_90>1and float(ws.cell(row＝i,column＝2).value)/Torque_max_160<1:

a＝round(float(Torque_max_160/ws.cell(row＝i,column＝2).value))*100

b＝round(float(Torque_max_90/ws.cell(row＝i,column＝2).value))*100

proportions_2＝list(range(0,b+1,1))

if T _ n < T _ max _ f _ n andT _ n < T _ max _ r _ n, the front and rear motor torque distribution coefficient ranges are defined as [ T _ max _ f _ n/Tmax _ n, T _ max _ r _ n/Tmax _ n ], the conditional judgment is realized by:

eliffloat(ws.cell(row＝i,column＝2).value)/Torque_max_160>1:

a＝math.floor((float(Torque_max_160/ws.cell(row＝i,column＝2).value)*100))

b＝math.ceil(float(Torque_max_90/ws.cell(row＝i,column＝2).value)*100)

proportions_3＝list(range(b,a,1))

the purpose of limiting the torque distribution coefficient range of the front motor and the rear motor is to ensure that the actually distributed torque of the front motor and the rear motor does not exceed the maximum torque capacity of the front motor and the rear motor at the current rotating speed.

S4, calculating the efficiency of the vehicle power system at each vehicle operating point, and calculating the output power of the front motor and the rear motor at each vehicle operating point according to the following formula: pinout _ front motor _ n ═ T _ n ═ n/9550 where n is 500,1000,1500 500,1000,1500 … 12500, pinout _ rear motor _ n ═ T _ n ═ n/9550 where n is 500,1000,1500 500,1000,1500 … 12500;

calculating the input power of the front motor and the rear motor according to the following formula: the pininpfore motor _ n is pinoutport _ fore motor _ n/η _ f _ n, where n is 500,1000,1500 500,1000,1500 … 12500, and pininpaft motor _ n is pinoutport _ aft motor _ n/η _ r _ n, where n is 500,1000,1500 500,1000,1500 … 12500;

calculating vehicle powertrain efficiency according to: η _ n is (pout _ front motor _ n + pout _ rear motor _ n)/(pout _ front motor _ n + pout _ rear motor _ n) × 0.97, where 0.97 is the front and rear reducer efficiency, which is merely illustrated for ease of understanding and the actual reducer efficiency is not limited.

The efficiency of the front motor and the efficiency of the rear motor at each working condition point in the formula are obtained by an interpolation method according to the actually measured efficiency data of the front motor and the rear motor, and in the script program written in the invention, the following sentences are the interpolation program of the efficiency of the front motor and the rear motor:

result_ef_90＝griddata(points_90,values_90,points_new_90,method＝'nearest')

result_ef_160＝griddata(points_160,values_160,points_new_160,method＝'nearest')

the interpolation method adopts a 'nearest value-taking method', wherein front and rear motor sample points in an interpolation program are obtained through the following sentences:

ws _90 ═ wb [ 'front motor external characteristic' ]

ws _160 ═ wb [ 'rear motor external characteristic' ]

rows＝ws.max_row

rows_90＝ws_90.max_row

rows_160＝ws_160.max_row

list_speed_90＝[]

list_torque_90＝[]

list_ef_90＝[]

for i in range(2,rows_90+1):

speed_90＝ws_90.cell(row＝i,column＝1).value

torque_90＝ws_90.cell(row＝i,column＝2).value

eff_90＝ws_90.cell(row＝i,column＝3).value

list_speed_90.append(speed_90)

list_torque_90.append(torque_90)

list_ef_90.append(eff_90)

list_new_90＝list(zip(list_speed_90,list_torque_90))

points_90＝np.array(list_new_90)

values_90＝np.array(list_ef_90)

list_speed_160＝[]

list_torque_160＝[]

list_ef_160＝[]

for i in range(2,rows_160+1):

speed_160＝ws_160.cell(row＝i,column＝1).value

torque_160＝ws_160.cell(row＝i,column＝2).value

eff_160＝ws_160.cell(row＝i,column＝3).value

list_speed_160.append(speed_160)

list_torque_160.append(torque_160)

list_ef_160.append(eff_160)

list_new_160＝list(zip(list_speed_160,list_torque_160))

points_160＝np.array(list_new_160)

values_160＝np.array(list_ef_160)

The previous motor sample point is (points _90, values _90) and the next motor sample point is (points _160, values _ 160).

The front motor interpolation point and the rear motor interpolation point are obtained through the following sentences:

points_new_90＝np.array([SPEED_90,TORQUE_90])

points_new_160＝np.array([SPEED_160,TORQUE_160])

after the sample points and the interpolation points are obtained, efficiencies result _ ef _90 and result _ ef _160 of the front and rear motor interpolation points can be obtained, and the vehicle powertrain efficiency of each operating point can be calculated by the following statements:

front_power_input＝((float(TORQUE_90)*float(SPEED_90))/9550/float(result_ef_90))*100

front_power_output＝(float(TORQUE_90)*float(SPEED_90))/9550*0.97

rear_power_input＝((float(TORQUE_160)*float(SPEED_160))/9550/float(result_ef_160))*100

rear_power_output＝(float(TORQUE_160)*float(SPEED_160))/9550*0.97

total_power_input＝front_power_input+rear_power_input

total_power_output＝front_power_output+rear_power_output

eff_n＝total_power_output/total_power_input

s5, after limiting the front and rear motor torque distribution coefficient ranges, finding out a point that optimizes the efficiency of the vehicle powertrain system within the limited coefficient range, and forming a front and rear motor torque distribution coefficient table with the optimized efficiency of the vehicle powertrain system from all the points, wherein the distribution table can be obtained by the following statements:

EFF_max.append(proportions[EFF.index(max(EFF))]/100)

EFF_max_coefficient.append(max(EFF))

through the steps, the torque distribution coefficient of each vehicle working condition point finally obtained by the example on which the invention depends is shown in the fourth table;

TABLE four vehicle operating points Torque distribution coefficients

Rotating speed (r/min)	Torque (Nm)	Distribution coefficient
			500	10	1
500	20	0
			500	30	0
…	…	…
			500	540	0.43
…
			12500	198	0.45

Referring to fig. 4, an embodiment of the present invention provides a pure electric vehicle torque distribution coefficient analysis system 100 based on Python, including:

the data reading and processing module 110 is used for reading the external characteristic data of the front motor and the external characteristic data of the rear motor through a Python third-party library openpyxl module, generating each vehicle working condition point according to a preset sampling rule, and acquiring the motor efficiency before sampling points and the motor efficiency after sampling points, wherein the sampling points are any number of the vehicle working condition points;

the operating point efficiency analysis module 120 is in communication connection with the data reading and processing module 110, and is used for interpolating to obtain the non-sampling point front motor efficiency and the non-sampling point rear motor efficiency in each vehicle operating point according to the sampling point front motor efficiency and the sampling point rear motor efficiency through a Python third-party library numpy module, a math module, a scipy module and a panda module; and the number of the first and second groups,

and the optimal distribution coefficient calculation module 130 is in communication connection with the operating point efficiency analysis module 120 and is used for analyzing the optimal torque distribution coefficient of each vehicle operating point according to the front motor efficiency and the rear motor efficiency, wherein the front motor efficiency comprises the front sampling point motor efficiency and the non-sampling point motor efficiency, and the rear motor efficiency comprises the rear sampling point motor efficiency and the rear non-sampling point motor efficiency.

The data reading processing module 110 includes:

a data reading unit 111 for reading the front motor external characteristic data and the rear motor external characteristic data;

the data processing unit 112 is in communication connection with the data reading unit 111, and is configured to determine a maximum rotation speed of the front motor, a maximum rotation speed of the rear motor, a maximum torque of the front motor at any rotation speed, and a maximum torque of the rear motor at any rotation speed according to the external characteristic data of the front motor and the external characteristic data of the rear motor, respectively, select a smaller value of the maximum rotation speed of the front motor and the maximum rotation speed of the rear motor as a maximum rotation speed of the power system, and select the maximum torque of the front motor and the maximum torque of the rear motor at any rotation speed as a maximum torque of the power system at any rotation; generating each vehicle working condition point by combining the maximum rotating speed of the power system and the maximum torque of the power system according to a preset sampling rule, wherein the vehicle working condition points comprise the rotating speed of a motor and the corresponding torque of the power system;

and the data acquisition unit 113 is in communication connection with the data processing unit 112 and is used for acquiring the motor efficiency before the sampling point and the motor efficiency after the sampling point, wherein the sampling points are any number of vehicle operating points.

The system further comprises:

a torque distribution constraint module 140, communicatively coupled to the operating point efficiency analysis module 120, for:

if the target power system torque is less than or equal to the first torque value T₁Then the torque distribution coefficient range for the target vehicle operating point is set to [0,1]]First value of torque T₁The lower value of the maximum torque of the front motor and the maximum torque of the rear motor at the target rotating speed is obtained;

Second torque value T₂The maximum torque of the front motor and the maximum torque of the rear motor are larger values under the target rotating speed;

The optimal distribution coefficient calculation module 130, communicatively coupled to the torque distribution constraint module 140, includes:

the grouping unit 131 is configured to set multiple groups of efficiency ratio pair groups within the torque distribution coefficient range, where the efficiency ratio pair groups subdivide the target power system torque into corresponding target front motor torque and target rear motor torque according to different torque distribution coefficients;

the motor efficiency analysis unit 132 is in communication connection with the grouping unit 131, and is configured to determine a corresponding target front motor efficiency according to the target rotation speed and the target front motor torque of the target vehicle operating point, and determine a corresponding target rear motor efficiency according to the target rotation speed and the target rear motor torque of the target vehicle operating point;

an efficiency obtaining unit 1333 for obtaining a front retarder efficiency and a rear retarder efficiency;

a system efficiency analysis unit 134, communicatively connected to the motor efficiency analysis unit 132 and the efficiency acquisition unit 133, for analyzing the power system efficiency of each efficiency ratio pair group according to the target front motor torque, the target rear motor torque, the target front motor efficiency, the target rear motor efficiency, the front retarder efficiency, and the rear retarder efficiency;

and an optimal coefficient analysis unit 135, communicatively connected to the system efficiency analysis unit 134, for determining an optimal torque distribution coefficient according to the power system efficiency.

The system efficiency analysis unit 134 includes:

an input power analysis subunit for obtaining the output power P of the front motor according to the target front motor torque₀₁Obtaining a post-motor output power P according to the target post-motor torque₀₂；

An output power analysis subunit, communicatively connected to the input power analysis subunit, for analyzing the target front motor efficiency η₁And front motor output power P₀₁Motor input power P before calculation₁₁，

A system efficiency analysis subunit, communicatively connected to the input power analysis subunit and the output power analysis subunit, for analyzing the output power P of the front motor₀₁Rear motor output power P₀₂Front motor input power P₁₁Rear motor input power P₁₂Front retarder efficiency eta₃And rear retarder efficiency η₄Analyzing the efficiency eta of the power system of each efficiency ratio pair group,

specifically, the functions of each module in this embodiment have been described in detail in the corresponding method embodiment, and thus are not described in detail again.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A Python-based pure electric vehicle torque distribution coefficient analysis method is characterized by comprising the following steps:

2. The method according to claim 1, wherein the step of reading the front motor external characteristic data and the rear motor external characteristic data through a Python third-party library openpyxl module and generating each vehicle operating point according to a preset sampling rule comprises the following steps:

3. The method according to claim 1, wherein before the step of analyzing the optimal torque distribution coefficient of each vehicle operating point according to a front motor efficiency and a rear motor efficiency, the front motor efficiency comprises the sampling point front motor efficiency and the non-sampling point front motor efficiency, and the rear motor efficiency comprises the sampling point rear motor efficiency and the non-sampling point rear motor efficiency, the method further comprises the following steps:

if the target power system torque is less than or equal toAt a first torque value T₁Then the torque distribution coefficient range for the target vehicle operating point is set to [0,1]]The first torque value is the smaller value of the maximum torque of the front motor and the maximum torque of the rear motor at the target rotating speed;

4. The method according to claim 3, wherein the step of analyzing the optimal torque distribution coefficient for each vehicle operating point according to a front motor efficiency and a rear motor efficiency, the front motor efficiency comprising the sampling point front motor efficiency and the non-sampling point front motor efficiency, and the rear motor efficiency comprising the sampling point rear motor efficiency and the non-sampling point rear motor efficiency, comprises the steps of:

5. The method of claim 4, wherein said step of analyzing powertrain efficiency for each efficiency ratio pair based on said target front motor torque, target rear motor torque, said target front motor efficiency, said target rear motor efficiency, said front retarder efficiency, and said rear retarder efficiency comprises the steps of:

6. the utility model provides a pure electric vehicles torque distribution coefficient analytic system based on Python which characterized in that includes:

7. The system of claim 6, wherein the data read processing module comprises:

8. The system of claim 6, wherein the system further comprises:

9. The system of claim 8, wherein the optimal distribution coefficient calculation module, coupled in communication with the torque distribution constraint, comprises:

10. The system of claim 9, wherein the system efficiency analysis unit comprises:

An output power analysis subunit, communicatively connected to the input power analysis subunit, for analyzing the target front motor efficiency η₁And the front electrodeMachine output power P₀₁Motor input power P before calculation₁₁，