CN114734834A - Electronic differential control system for double motors of rear axle of electric vehicle - Google Patents

Electronic differential control system for double motors of rear axle of electric vehicle Download PDF

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Publication number
CN114734834A
CN114734834A CN202210482104.5A CN202210482104A CN114734834A CN 114734834 A CN114734834 A CN 114734834A CN 202210482104 A CN202210482104 A CN 202210482104A CN 114734834 A CN114734834 A CN 114734834A
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control module
yaw
rear wheel
motor
wheel
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汪选要
程王峰
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Institute of Environment Friendly Materials and Occupational Health of Anhui University of Sciece and Technology
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Institute of Environment Friendly Materials and Occupational Health of Anhui University of Sciece and Technology
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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
    • B60L15/2036—Electric differentials, e.g. for supporting steering 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
    • 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/46—Drive Train control parameters related to wheels
    • B60L2240/461—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
    • B60L2260/00—Operating Modes
    • B60L2260/40—Control modes
    • B60L2260/48—Control modes by fuzzy logic
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)
  • Arrangement And Driving Of Transmission Devices (AREA)
  • Arrangement And Mounting Of Devices That Control Transmission Of Motive Force (AREA)

Abstract

The invention discloses a double-motor electronic differential control system of a rear axle of an electric vehicle, which comprises a rear axle double-motor assembly mechanism, an Ackerman steering analysis model, a yaw motion control module, a fuzzy control module and a coordination control module. The rear axle double-motor assembly mechanism is used for upgrading and optimizing the structure of the rear axle double-motor assembly mechanism; the Ackerman steering analysis model is used for acquiring the turning radius and the rotating speed of the left rear wheel or the right rear wheel of the electric vehicle; a yaw motion control module for obtaining a yaw rate w during steeringrSetting a triggering condition and outputting an additional yaw moment delta M under the yaw motion; a fuzzy control module for improving the deviation of the yaw rate from the expected value state and the change rate of the deviation and outputting a driving torque TsrrAnd TsrlAdditional yaw moment Δ M under sum fuzzy control1(ii) a A coordination control module for coordinating the outputs of the yaw motion control module and the fuzzy control module and outputting the actual driving torque Trr、TrlAnd the motor is regulated.

Description

Electronic differential control system for double motors of rear axle of electric vehicle
Technical Field
The invention relates to the field of vehicle rear axle control, in particular to a double-motor electronic differential control system for a rear axle of an electric vehicle.
Background
With the development of science and technology, mechanical differentials have many advantages, but have some disadvantages, such as limited applicable conditions (not applicable to high-speed driving, not applicable to paving road surfaces) and large damage to driving systems. In addition, the mechanical differential is limited in size, and the device is not suitable for application in electric vehicles.
In order to solve the problems, an Electronic Differential (EDS) is developed as an expansion part of a wheel speed sensor, and the working principle of the EDS is to judge whether wheels lose the grounding friction force according to the rotating speeds of left and right wheels, apply a braking force to the wheels losing the grounding friction force, effectively apply a driving force to non-slipping wheels, and ensure the stable running of a vehicle.
The embodiment of the invention is provided with two motors on the rear axle, although the invention is easy to realize and convenient to install, and can realize high-power and high-torque output when being applied to the rear axle of the electric vehicle, the installation of a mechanical differential on the rear axle of the electric vehicle can lead to the increase of the weight of the electric vehicle, the reduction of the space of the whole vehicle and the increase of the cost.
The embodiment of the invention can adjust the torque distribution of a middle and rear axle to achieve the purpose of axle difference slip limiting, but does not omit that an interaxial differential drives a middle axle motor and a rear axle motor through a transmission shaft, and the motors are respectively arranged at the positions of the middle axle and the rear axle, so that the distribution is wide, and the compactness in the structure is not achieved. In the aspect of control, the corresponding rotating speeds of the two motors are respectively calculated through the rotating speed difference of the two motors, the calculation process is complex, and the calculation time of a control part is increased.
The prior patent (publication number: CN107757357A) discloses a cross-feedback electronic differential system and a control method thereof, in order to ensure that an electric vehicle normally runs under ice-skating, muddy and other road conditions, a differential lock function is added into the system, the performance of the electric vehicle is improved, and the cross-feedback electronic differential system has great potential in the field of electric vehicles. However, the cross-feedback electronic differential system is not mentioned to be applied to the field of electric vehicles, for example, the electronic differential control of the two motors of the rear axle of the electric vehicle and the electronic differential control of the four-wheel-drive hub motor have certain difference, so the practicability of the cross-feedback electronic differential system needs to be further enhanced.
In view of the above, the conventional electronic differential control system also has the following problems: 1. the driving torque is solved by using a PID (proportion integration differentiation) or fuzzy control algorithm in the conventional electronic differential system, although the differential speed of the left wheel and the right wheel can be realized, the algorithm has low solving precision and long operation time, so that the control precision of the differential system is low, the response time is long, and the stability of a vehicle in the differential process is relatively poor; 2. although the wheel speeds of the wheels can be solved through the conventional Ackerman steering analysis model, the model ignores the nonlinear disturbance influence of the vehicle in the steering process, so that a certain error exists between the actual driving torque and an ideal value, and the stability of the vehicle in the differential process is reduced.
Disclosure of Invention
The invention aims to provide a double-motor electronic differential control system for a rear axle of an electric vehicle, which aims to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme: the device mainly functions in meeting the requirements of upgrading and optimizing the structure of the device, the Ackerman steering analysis model is used for obtaining the radiuses of the left rear wheel and the right rear wheel of the electric vehicle and the rotating speed values of the left rear wheel and the right rear wheel, and the yawing motion control module is used for obtaining the corresponding yawing angular velocity w when the electric vehicle turns under the Ackerman steering analysis modelrSetting the corresponding trigger condition when making the yaw movement and outputting the corresponding additional yaw moment delta M, a fuzzy control module for improving the deviation between the yaw velocity and the expected value and the change rate of the deviation and the like and outputting the corresponding driving moment TsrrAnd
Figure BDA0003627936590000021
and additional yaw moment DeltaM of fuzzy control output1The coordination control module is used for outputting a yaw moment delta M for the yaw movement and outputting a driving moment T under fuzzy controlsrr、
Figure BDA0003627936590000022
And additional yaw moment Δ M1Corresponding coordination is carried out, and the final target driving torque T is outputrr、TrlThe motor is adjusted accordingly.
As another preferable scheme, the Ackerman steering analytic model ignores a longitudinal and vertical translation and 6-degree-of-freedom stress model of rotation of the three axes when the whole vehicle is stressed, and when the steering angle delta is set to change at a small angle, the speed of the centroid point is mainly based on the longitudinal vehicle speed u, and the speed value of the centroid point is equal to the longitudinal vehicle speed, namely u is approximately equal to v. According to the known distance l from the front wheel to the center of massfAnd the distance from the front wheel to the rear wheel is l, then the distance from the rear wheel to the center of mass is l-lfI.e. when the velocity value at the centroid equals the corner radius to the yaw rate wrProduct of (a): u-wrR, so for formula variations there are
Figure BDA0003627936590000023
The distance between the left and right track pitches is d, that is, at this time, according to the Ackerman steering analysis model and the geometric relationship of the right triangle, it can be known that:
Figure BDA0003627936590000024
namely, the steering radiuses of the left rear wheel and the right rear wheel are as follows:
Figure BDA0003627936590000025
respectively acquiring the speeds of the left rear wheel and the right rear wheel according to the Ackerman steering analysis model, and expressing the speeds as follows:
Figure BDA0003627936590000031
then, the angular velocities and the rotational speed values corresponding to the left and right rear wheels are obtained according to the angular velocity formula and the rotational speed formula.
As a preferable scheme of the invention, the rear axle double-motor assembly mechanism comprises a central control unit (MCU), a speed reducer, an electronic differential, a half shaft, a first motor, a second motor, a left rear wheel, a right rear wheel, a first wheel speed sensor and a second wheel speed sensor. The first motor and the second motor are coaxially arranged, the output ends of the first motor and the second motor are provided with speed reducers, a central controller MCU is arranged above the speed reducers, the output ends of the speed reducers are connected with half shafts, the number of the half shafts is two, the other ends of the half shafts are respectively connected with a left rear wheel and a right rear wheel, and a first wheel speed sensor and a second wheel speed sensor are respectively arranged on the inner sides of the left rear wheel and the right rear wheel.
As another preferred aspect of the present invention, the yaw control module obtains a corresponding yaw velocity value of the electric vehicle during steering under an Ackerman steering analysis model, controls a swing amplitude of a yaw motion of the electric vehicle during traveling in order to ensure tracking performance of the electric vehicle, and outputs a corresponding additional yaw moment Δ M, and simultaneously, sets triggering conditions of the yaw motion control module to: δ is not equal to 0 and u is not less than ubWhile satisfying wr≥wrb。ub，
Figure BDA0003627936590000032
Setting u for the vehicle speed threshold value and yaw rate threshold value under the triggering conditionbIs 55km/h, wrIs 0.05 rad/s.
As another preferable scheme of the invention, the fuzzy control module obtains a fuzzy subset by using fuzzy language description according to the left and right rear wheel rotating speed values obtained under the Ackerman steering analysis model, and performs fuzzy decision on the fuzzy subset according to a control rule, so as to obtain the corresponding driving torque. And finally, converting the obtained driving torque into the driving torque with higher accuracy through clarification. To reduce the deviation of the yaw rate from the desired value, and the rate of change of the deviation, thereby improving the electric vehicle turning left,steering stability under right-hand turn and wheel slip, and output a corresponding additional yaw moment Δ M1。
As another preferred embodiment of the present invention, the coordination control module controls the yaw rate by the additional yaw moment outputted from the yaw motion control module and the fuzzy control module when the yaw rate w isrWhen decreasing, the yaw moment output should be increased, and vice versa. Meanwhile, the additional yaw moment Delta M output by the yaw motion control module and the driving moment T output by the fuzzy control modulesrr、TsrlAnd additional yaw moment Δ M1Outputs of the three are coordinated to output the target drive torque Trr、TrlAnd the motor is regulated.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with the prior art, the scheme adopts an Ackerman analysis model and a fuzzy control rule, deduces the steering radiuses of the left rear wheel and the right rear wheel according to the Ackerman steering analysis model, and simplifies the target driving torque T through the fuzzy control rulerr、TrlTo raise the target drive torque Trr、TrlThe solving speed of the differential system is improved, the stability in the differential process is improved finally, and the operation time of the differential system is reduced.
2. The scheme considers the nonlinear factors in the steering process, and is provided with a yaw control module and a coordination control module for controlling the swing amplitude of the yaw motion of the vehicle in the driving process and coordinating the target driving torque Trr、TrlReducing the target drive torque Trr、TrlAnd the deviation from the ideal value better realizes the differential speed of the left wheel and the right wheel and ensures the stable running of the vehicle.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
In the drawings:
FIG. 1 is a schematic diagram of the overall vehicle control system logic of the present invention;
FIG. 2 is a schematic diagram of an Ackerman steering analytic model according to the present invention;
FIG. 3 is a schematic structural diagram of an electrically driven rear axle dual-motor assembly mechanism of the present invention;
FIG. 4 is a schematic diagram of the control logic for the electronic differential system of the present invention;
FIG. 5 is a schematic flow chart of the present invention under three conditions;
the reference numbers in the figures illustrate: a rear axle double-motor assembly mechanism 1; ackerman turns to analytical model 2; a yaw motion control module 3; a fuzzy control module 4; a coordination control module 5; a vehicle model 6; a central controller MCU 101; a speed reducer 102; an electronic differential 103; half shafts 104; a first motor 105; a second motor 106; a left rear wheel 107; a right rear wheel 108; a wheel speed sensor I109; a second wheel speed sensor 110; a left front wheel 201; a right front wheel 202;
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to 5, the present invention provides a technical solution:
the electronic differential control system comprises a rear axle double-motor assembly mechanism 1, an Ackerman steering analysis model 2, a yaw motion control module 3, a fuzzy control module 4, a coordination control module 5 and a rear axle double-motor assembly mechanism 1, wherein the device is mainly used for upgrading and optimizing the structure of the rear axle double-motor assembly mechanism, the Ackerman steering analysis model 2 is used for obtaining the turning radius of a left rear wheel 107 and a right rear wheel 108 of an electric vehicle, the rotating speed value of the left rear wheel 107 and the rotating speed value of the right rear wheel 108, and the yaw motion control module 3 is used for obtaining the corresponding yaw velocity w when the electric vehicle turns under the Ackerman steering analysis modelrAnd is set to perform a yaw movementTriggering conditions during the movement and outputting an additional yaw moment Delta M, a fuzzy control module 4 for improving the deviation between the yaw rate and the desired value and the change rate of the deviation, and outputting a corresponding driving moment TsrrAnd
Figure BDA0003627936590000051
and additional yaw moment DeltaM output by fuzzy control1A coordination control module 5 for outputting a yaw moment Delta M for the yaw motion and a driving moment T under fuzzy controlsrr、
Figure BDA0003627936590000052
And additional yaw moment Δ M1Corresponding coordination is carried out, and the target driving torque T is outputrr、TrlAnd correspondingly adjusting the first motor 105 and the second motor 106.
As another embodiment of the present invention, as shown in fig. 1 and 2, in the Ackerman steering analysis model 2, the steering angles of the left front wheel 201 and the right front wheel 202 are δ respectivelyinAnd deltaoutWhen a steering angle delta is set to change at a small angle by neglecting a 6-degree-of-freedom stress model of longitudinal, vertical and translational motion and rotation of the three axes when the whole vehicle is stressed, the speed at the mass center point is mainly determined according to the longitudinal speed u, and the speed value at the mass center point is enabled to be equal to the longitudinal speed value according to the stability control of the ESP whole vehicle, namely u is approximately equal to v. According to the known distance l from the front wheel to the center of massfThe distance from the front left wheel 201 to the rear left wheel 107 is l. Similarly, the distance from the front right wheel 202 to the rear right wheel 108 is also l. At the moment, the distance from the rear wheel to the center of mass is l-lfThat is, as can be seen from the velocity formula, the velocity value at the centroid is equal to the corner radius and the yaw rate wrProduct of (a): u-wrR, so for formula variations there are
Figure BDA0003627936590000053
The distance between the left and right track widths of the rear wheels is d, that is, at this time, it is known from the Ackerman steering analysis model 2 and the geometric relationship of the right triangle that:
Figure BDA0003627936590000054
that is, the turning radii of the left rear wheel 107 and the right rear wheel 108 are:
Figure BDA0003627936590000055
according to the Ackerman steering analysis model 2, the speeds of the left rear wheel 107 and the right rear wheel 108 are respectively obtained, and are expressed as:
Figure BDA0003627936590000056
as for the velocities of the left rear wheel 107 and the right rear wheel 108 described above, the angular velocity values of the left rear wheel 107 and the right rear wheel 108 can be obtained by the following formula:
Figure BDA0003627936590000057
substituting the above calculated speeds of the left rear wheel 107 and the right rear wheel 108 and the steering radius of the left rear wheel 107 and the right rear wheel 108, the angular speeds of the left rear wheel 107 and the right rear wheel 108 are:
Figure BDA0003627936590000061
then the rotation speed values of the corresponding left rear wheel 107 and right rear wheel 108 at this time are:
Figure BDA0003627936590000062
in summary, when a 6-degree-of-freedom stress model of longitudinal, vertical, translational and rotational motions of the three axes when the whole vehicle is stressed is ignored, and when the steering angle δ is set to change at a small angle (the general absolute value changes at about 5 °), the angular velocity values and the rotational velocity values of the left rear wheel 107 and the right rear wheel 108 are derived according to the Ackerman steering analytic model 2 and the Ackerman steering analytic model, and at a given vehicle speed v, the corresponding angular velocity values and the rotational velocity values of the left rear wheel 107 and the right rear wheel 108 under the condition are obtained through a derived formula and are used under the following three working conditions.
As an embodiment of the present invention, as shown in fig. 3, the rear axle dual-motor assembly mechanism 1 includes a central controller MCU101, a speed reducer 102, an electronic differential 103, a half shaft 104, a first motor 105, a second motor 106, a left rear wheel 107, a right rear wheel 108, a first wheel speed sensor 109, and a second wheel speed sensor 110. The utility model provides a wheel speed sensor, including first motor 105, second motor 106 coaxial arrangement, the output of first motor 105 and second motor 106 is provided with reduction gear 102, the top of reduction gear is provided with central controller MCU101, the output of reduction gear is connected with the semi-axis, the semi-axis has two, two the other end of semi-axis is connected with left rear wheel 107 and right rear wheel 107 respectively, left rear wheel 107 and right rear wheel 108 inboard are provided with fast sensor 109 of wheel and fast sensor two 110 of wheel respectively.
The rear axle double-motor assembly mechanism 1 isolates vibration parts such as a first motor 105, a second motor 106, a speed reducer 102 and the like from electric parts such as a central control unit MCU101 and the like, and isolates the vibration parts from a vehicle body and a chassis, so that the transmission of vibration impact to the vehicle body is reduced, the service lives of the first motor 105 and the second motor 106 and the efficiency of rotating speed are prolonged, and the electric vehicle can run more stably. The electronic differential mechanism 103 is arranged inside the speed reducer 102, so that the space of a rear axle of the whole vehicle is saved, the electronic differential mechanism 103 is protected, and meanwhile, the structure is compact, so that the efficiency and the safety performance of the electric vehicle are further improved in the differential process.
As another embodiment of the present invention, as shown in fig. 2 and 4, the yaw control module 3 obtains a corresponding yaw velocity value of the electric vehicle during steering under the Ackerman steering analysis model 2, and controls the swing amplitude of the yaw motion of the electric vehicle during driving and outputs a corresponding additional yaw moment Δ M in order to ensure the tracking performance of the electric vehicle, and meanwhile, in order to reduce the cost of the electronic differential, the triggering conditions of the yaw motion control module 3 are set as follows in consideration of wheel slip and left-and right-turn conditions: δ ≠ 0 andu≥ubwhile satisfying wr≥wrb。ub、wrbRespectively, a threshold value for the vehicle speed and a threshold value for the yaw rate under triggering conditions, assuming ubIs 55km/h, wrbIs 0.05 rad/s.
Under the Ackerman steering analysis model 2, when a given speed v is greater than 55km/h, neglecting a 6-degree-of-freedom stress model of longitudinal, transverse, vertical and three-axis rotation when the whole vehicle is stressed, setting a steering angle delta to be changed at a small angle (generally, the absolute value is changed at about 5 degrees), and deducing angular speed values of the left rear wheel 107 and the right rear wheel 108 and rotating speed values of the left rear wheel 107 and the right rear wheel 108 according to the Ackerman steering analysis model 2 and the Ackerman steering analysis model 2. Note that at a certain speed of travel, the value of the yaw rate increases as the steering wheel angle increases. When the electric vehicle is in the process of yaw movement, the change of the yaw velocity is controlled by the generated additional yaw moment delta M, so that the situation that the stability of the electric vehicle is reduced under the conditions of left turning, right turning and wheel slipping caused by overlarge change of the yaw velocity is prevented, and the driving safety is influenced.
As another embodiment of the present invention, as shown in fig. 4 and 5, the fuzzy control module 4 obtains a fuzzy subset by using a fuzzy language description according to the rotation speed values of the left rear wheel 107 and the right rear wheel 108 obtained under the Ackerman steering analytic model 2, and performs fuzzy decision on the fuzzy subset according to a control rule, so as to obtain a corresponding driving torque. Finally, the obtained driving torque is converted into driving torque T with higher precision through clarificationsrr，
Figure BDA0003627936590000071
Meanwhile, the device is used for reducing the deviation of the yaw angular velocity from the expected value and the deviation change rate, improving the operation stability of the electric vehicle under three working conditions of left turning, right turning and wheel slipping and outputting corresponding additional yaw moment delta M1The specific working conditions of the electronic differential control system under the three working conditions are described in detail as follows:
when the electric vehicle is in a left turning working condition, the first wheel speed sensor 109 and the second wheel speed sensor 110 detect the left rear wheel 107 and the right rear wheel 108 are inconsistent in rotating speed, at the moment, wheel speed signals are transmitted to the central controller MCU101, the central controller MCU101 receives signals indicating that the wheel speeds of the left rear wheel 107 and the right rear wheel 108 are inconsistent, differential signal instructions are transmitted to the electronic differential control system module, and a speed value formula of the left rear wheel 107 and the right rear wheel 108 under a set condition is obtained according to the Ackerman steering analysis model 2:
Figure BDA0003627936590000072
as is apparent from the above-described speeds of the left rear wheel 107 and the right rear wheel 108, the angular velocity values of the left rear wheel 107 and the right rear wheel 108 are expressed by the following equations:
Figure BDA0003627936590000073
substituting the above calculated speeds of the left rear wheel 107 and the right rear wheel 108, and the radius of the left rear wheel 107 and the right rear wheel 108 can obtain:
Figure BDA0003627936590000081
then the rotation speed of the corresponding left rear wheel 107 and right rear wheel 108 at this time is:
Figure BDA0003627936590000082
according to the derivation formula, the rotation speed values of the left rear wheel 107 and the right rear wheel 108 under the current condition are obtained, and after the swing amplitude of the yaw motion is correspondingly controlled by the yaw control module 3, the corresponding change of the yaw angular speed is controlled by using the additional yaw moment delta M output by the yaw motion. And according to a fuzzy control rule, improving the deviation change rate corresponding to the yaw angular velocity, and simultaneously inquiring a fuzzy matrix table to adjust parameters. The output is the left rear wheel 107 and the right rear of the self-adaptationThe rotating speed value of the wheel 108 is accurately reasoned, the error of the rotating speed value in the fuzzification reasoning process is reduced, and corresponding driving torque T is outputsrr、TsrlAnd an additional yaw moment DeltaM outputted by the fuzzy control1Transmitted to a coordination control module 5 and is based on the additional yaw moment Delta M output by a yaw motion control module 3 and the driving moment T output by a fuzzy control module 4srrAnd TsrlAdditional yaw moment Δ M1According to the coordinated control module 5, the input driving torque T is inputsrr、TsrlAnd additional yaw moments DeltaM, DeltaM under yaw motion and fuzzy control1Corresponding coordination is carried out, and the target driving torque T is outputrr、TrlThe rotation speed is transmitted to the first motor 107 and the second motor 108, and then the amplitude of the rotation speed value is controlled through the speed reducer 102, so that the left rear wheel 107 and the right rear wheel 108 obtain corresponding rotation speed values, and finally the electric vehicle achieves stable differential operation.
In a similar way, when the electric vehicle runs under the working condition of right turning and wheel slipping, the working process of the electronic differential control system is similar to that under the working condition of left turning of the electric vehicle, and finally, when the electric vehicle runs under the working condition of right turning, left wheel or right wheel slipping, the stable running of the electric vehicle in the running process is ensured.
As another embodiment of the present invention, as shown in fig. 4 and 5, the coordination control module 5 controls the yaw rate by the additional yaw moment output by the yaw motion control module 3 and the fuzzy control module 4 when the yaw rate w isrWhen decreasing, the yaw moment output should be increased, and vice versa. Meanwhile, the additional yaw moment Delta M output by the yaw motion control module 3, the driving moment and the additional yaw moment output by the fuzzy control module 4 and the driving moment T output by the fuzzy control module 4srrAnd TsrlOutput of the three is coordinated to output the target driving torque Trr、TrlThe first motor 107 and the second motor 108 are supplied, and then the motors are adjusted accordingly.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that various changes, modifications and substitutions can be made without departing from the spirit and scope of the invention as defined by the appended claims. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims (6)

1. The utility model provides an electric motor car rear axle bi-motor electron differential control system which characterized in that: the double-motor electronic differential control system for the rear axle of the electric vehicle comprises: the device comprises a rear axle double-motor assembly mechanism, an Ackerman steering analysis model, a yaw motion control module, a fuzzy control module and a coordination control module. The rear axle double-motor assembly mechanism is used for meeting the requirements of upgrading and optimizing the self structure; the Ackerman steering analysis model is used for acquiring the radius of the left and right rear wheels and the rotating speed value of the left and right rear wheels of the electric vehicle; the yaw motion control module is used for acquiring corresponding yaw velocity w when the electric vehicle turns under the Ackerman steering analysis modelrSetting corresponding trigger conditions when the yaw movement is carried out, and outputting corresponding additional yaw moment delta M; the fuzzy control module is used for improving deviation and change rate of the deviation under the state that the yaw angular velocity is equal to the expected value and outputting corresponding driving torque TsrrAnd
Figure FDA0003627936580000011
and additional yaw moment DeltaM of fuzzy control output1(ii) a The coordination control module is used for outputting a yaw moment delta M for yaw motion and a driving moment T output under fuzzy controlsrr、
Figure FDA0003627936580000012
And additional yaw moment Δ M1Corresponding coordination is carried out, and the final target driving torque T is outputrr、TrlThereby making corresponding adjustments to the motor.
2. The electric vehicle rear axle double-motor electronic differential as claimed in claim 1Speed control system, its characterized in that: the Ackerman steering analysis model ignores a longitudinal, transverse and vertical stress model with 6 degrees of freedom, wherein the stress model rotates along the three axes when the whole vehicle is stressed, when a steering angle delta is set to change at a small angle, the speed at a mass center point is mainly based on a longitudinal vehicle speed u, the speed value at the mass center point is equal to the longitudinal vehicle speed, namely u is approximately equal to v, the longitudinal speed u is equal to the vehicle speed v and is a uniform variable, and the distance from a known front wheel to the mass center is lfAnd the distance from the front wheel to the rear wheel is l, and the distance from the rear wheel to the center of mass at the moment is l-lfI.e. when the velocity value at the centroid is equal to the corner radius R and the yaw rate wrThe product of (a): u-wrR, so for formula variations there are
Figure FDA0003627936580000013
The distance between the left and right track pitches is d, that is, at this time, according to the Ackerman steering analysis model and the geometric relationship of the right triangle, it can be known that:
Figure FDA0003627936580000014
Figure FDA0003627936580000015
namely, the steering radiuses of the left rear wheel and the right rear wheel are as follows:
Figure FDA0003627936580000016
respectively acquiring the speeds of the left rear wheel and the right rear wheel according to the Ackerman steering analysis model:
Figure FDA0003627936580000017
then, the angular velocities and the rotational speed values corresponding to the left and right rear wheels are respectively obtained according to the angular velocity formula and the rotational speed formula.
3. The electric vehicle rear axle double-motor electronic differential control system as claimed in claim 1, characterized in that: the rear axle double-motor assembly mechanism (1) comprises a central control unit MCU (101), a speed reducer (102), an electronic differential (103), a half shaft (104), a first motor (105), a second motor (106), a left rear wheel (107), a right rear wheel (108), a first wheel speed sensor (109) and a second wheel speed sensor (110). The motor is one (105), motor two (106) coaxial arrangement, the output of motor one (105) and motor two (106) is provided with reduction gear (102), the top of reduction gear is provided with central controller MCU (101), the output of reduction gear is connected with the semi-axis, the semi-axis has two, two the other end of semi-axis is connected with left rear wheel (107) and right rear wheel (107) respectively, left rear wheel (107) and right rear wheel (108) inboard are provided with fast sensor one (109) of wheel and fast sensor two (110) of wheel respectively.
4. The electric vehicle rear axle double-motor electronic differential control system as claimed in claim 1, characterized in that: the yaw control module acquires a corresponding yaw velocity value of the electric vehicle during steering under an Ackerman steering analysis model, controls the swing amplitude of yaw motion of the electric vehicle during driving in order to ensure the tracking performance of the electric vehicle, and outputs a corresponding additional yaw moment delta M, and simultaneously sets the triggering conditions of the yaw motion control module as follows in consideration of the conditions of wheel slip, left turning and right turning in order to reduce the cost of an electronic differential mechanism: δ ≠ 0 and u ≧ ubWhile satisfying wr≥wrb。ub、wbAre a threshold value for vehicle speed and a threshold value for yaw rate under triggering conditions.
5. The electric vehicle rear axle double-motor electronic differential control system as claimed in claim 1, characterized in that: the fuzzy control module obtains the fuzzy values of the rotating speeds of the left rear wheel and the right rear wheel by using the fuzzy language description according to the rotating speeds of the left rear wheel and the right rear wheel obtained by the Ackerman steering analysis modelSubset, fuzzy decision is carried out on the fuzzy subset according to the control rule, and thus corresponding driving torque T is obtainedsrr，
Figure FDA0003627936580000021
Finally, the obtained driving torque is converted into driving torque T with higher precision through clarificationrr，
Figure FDA0003627936580000022
Meanwhile, the method is used for reducing the deviation of the yaw velocity from the expected value and the change rate of the deviation, thereby improving the operation stability of the electric vehicle under three working conditions of left turning, right turning and wheel slip and outputting corresponding additional yaw moment delta M1。
6. The electric vehicle rear axle double-motor electronic differential control system according to claim 1, characterized in that: the coordination control module controls the yaw rate through the additional yaw moment output by the yaw motion control module and the fuzzy control module when the yaw rate w isrWhen the yaw moment is reduced, the output of the yaw moment is increased, and vice versa, and meanwhile, the additional yaw moment delta M output by the yaw motion control module, the driving moment output by the fuzzy control module, the additional yaw moment and the driving moment T output by the fuzzy control module are usedsrrAnd TsrlOutputs of the three are coordinated to output the final target drive torque TrrAnd TrlAnd the motor is regulated.
CN202210482104.5A 2022-05-05 2022-05-05 Electronic differential control system for double motors of rear axle of electric vehicle Pending CN114734834A (en)

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Publication number Priority date Publication date Assignee Title
CN103879307A (en) * 2014-03-13 2014-06-25 浙江大学 Rear wheel independent drive control system and method for electric automobile
CN106184199A (en) * 2016-07-07 2016-12-07 辽宁工业大学 The integrated control method of distributed AC servo system electric automobile stability
CN108177693A (en) * 2017-12-28 2018-06-19 厦门大学 Wheel hub drives the electronic differential control system of electric vehicle
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CN110979022A (en) * 2019-11-12 2020-04-10 珠海格力电器股份有限公司 Control method and system for electronic differential of electric automobile and electric automobile
CN111873810A (en) * 2020-01-14 2020-11-03 湖南铁路科技职业技术学院 Distributed driving electronic differential self-adaptive control system
CN113353061A (en) * 2021-07-14 2021-09-07 广东工业大学 Four-motor-driven FSAE racing car electronic differential algorithm based on sliding mode control

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103879307A (en) * 2014-03-13 2014-06-25 浙江大学 Rear wheel independent drive control system and method for electric automobile
CN106184199A (en) * 2016-07-07 2016-12-07 辽宁工业大学 The integrated control method of distributed AC servo system electric automobile stability
CN108177693A (en) * 2017-12-28 2018-06-19 厦门大学 Wheel hub drives the electronic differential control system of electric vehicle
CN108819796A (en) * 2018-05-30 2018-11-16 河北工业大学 The automated steering control method of double wheel hub motor powered automobile
CN110979022A (en) * 2019-11-12 2020-04-10 珠海格力电器股份有限公司 Control method and system for electronic differential of electric automobile and electric automobile
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