CN110239363B - Dynamic stabilizing system of electric automobile - Google Patents
Dynamic stabilizing system of electric automobile Download PDFInfo
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- CN110239363B CN110239363B CN201910553526.5A CN201910553526A CN110239363B CN 110239363 B CN110239363 B CN 110239363B CN 201910553526 A CN201910553526 A CN 201910553526A CN 110239363 B CN110239363 B CN 110239363B
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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
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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
- B60L15/32—Control or regulation of multiple-unit electrically-propelled vehicles
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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
- B60L2220/00—Electrical machine types; Structures or applications thereof
- B60L2220/40—Electrical machine applications
- B60L2220/44—Wheel Hub motors, i.e. integrated in the wheel hub
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/72—Electric energy management in electromobility
Abstract
The invention discloses a dynamic stabilization system of an electric automobile, which belongs to the technical field of automobiles and comprises a turning radius calculation module, a speed ratio measurement module, an offset ratio calculation module, a wheel power ratio measurement module and a power distribution module, wherein virtual wheels are arranged at the central points of a front shaft and a rear shaft, the turning radius is obtained through the turning angle and the shaft distance, the triangular relation formed by the turning angle, the shaft distance and the rear shaft is calculated by using a mathematical triangle formula, the speed ratio of an inner side wheel and an outer side wheel is obtained by combining the wheel distance, the mass of the automobile and the real-time speed calculation are used as the speed basis, the centrifugal power proportion is offset on the basis of compensating the speed difference, and the power setting of a driving wheel is almost equal to the effects of turning speed compensation and offset centrifugation, so that a more stable driving posture is achieved.
Description
Technical Field
The invention relates to the technical field of automobiles, in particular to a four-wheel electric automobile double-motor and four-motor driving assisting and power distributing system.
Background
Four-wheel electric vehicles can be classified into two-motor (front drive/rear drive) and four-motor (four-drive) electric vehicles.
Taking a four-wheel all-wheel-drive electric automobile as an example, generally four driving wheels are respectively controlled by a hub motor independently to independently adjust the rotating speed and the torque of each wheel, the increase and decrease of the driving torque and the change of the vehicle speed are realized without a gearbox, a reducer and the like, the differential function of left and right wheels is realized without a differential, and the four-wheel all-wheel-drive electric automobile is easily influenced by self and external conditions to cause four-wheel dynamic unbalance.
As described above, the electric vehicle needs to turn during traveling, and the speed difference between the inner wheel and the outer wheel due to steering easily causes power loss of the outer wheel due to steering, and the inertia of the vehicle is mismatched, resulting in insufficient steering and dynamic imbalance of the vehicle.
Disclosure of Invention
The present invention is directed to solve the above problems, and an object of the present invention is to provide a dynamic stabilization system for an electric vehicle, which can distribute driving power, and achieve a more stable driving posture by setting the power of an outer wheel to be almost equal to a turning speed compensation and a centrifugal offset effect.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
electric automobile dynamic stabilization system includes:
a turning radius calculation module: the system is used for defining that a front virtual wheel corresponding to the front wheel is arranged at the central point of a front shaft, a rear virtual wheel corresponding to the rear wheel is arranged at the central point of a rear shaft, and calculating to obtain a coaxial driving wheel and the turning radius of the shaft virtual wheel according to the steering angle of the electric automobile and by combining the wheel spacing of the electric automobile and the wheel base of the front wheel and the rear wheel;
the speed ratio measuring and calculating module: the speed ratio of the coaxial driving wheel of the electric automobile to the virtual wheel of the shaft is obtained through calculation according to the coaxial driving wheel of the electric automobile and the turning radius of the virtual wheel of the shaft; specifically, the ratio of the turning radius of the outer wheel and the turning radius of the inner wheel of the coaxial driving wheel to the virtual wheel of the shaft are obtained through calculation, or the ratio of the turning radius of the outer wheel and the turning radius of the inner wheel of the driving wheel to the virtual wheel of the rear shaft are obtained through calculation, and the ratios are used as the speed ratio of the outer wheel and the inner wheel of the driving wheel to the virtual wheel;
the offset ratio calculation module: the offset proportion used for offsetting the centrifugal force action of the coaxial driving wheel of the electric automobile compared with the virtual wheel of the shaft is calculated and obtained according to the mass of the electric automobile;
the wheel power ratio measuring and calculating module comprises: the power distribution ratio for superposing and offsetting the centrifugal force action of the electric automobile driving wheel on the basis of compensating the speed difference is calculated and obtained according to the turning radius, the speed ratio and the offsetting proportion of the coaxial driving wheel of the electric automobile and the turning radius of the virtual wheel of the shaft; when the electric automobile is driven by a front wheel or a rear wheel, acquiring speeds of the outer side wheel and the inner side wheel of the driving wheel respectively, which are superposed to offset the action of centrifugal force on the basis of compensating speed difference compared with the virtual wheel of the shaft, according to the turning radius, the speed ratio and the offset ratio of the coaxial driving wheel and the turning radius of the virtual wheel of the shaft, and then acquiring the power distribution ratio of the power of the outer side wheel and the power of the inner side wheel of the driving wheel compared with the total output power of the driving wheel respectively according to the speeds of the outer side wheel and the inner side wheel of the driving wheel; when the electric automobile is driven by four wheels, acquiring speeds of the outer side wheel and the inner side wheel of the driving wheel respectively in comparison with the rear virtual wheel on the basis of compensating speed difference by superposing and offsetting centrifugal force action according to the turning radius, the speed occupation ratio and the offsetting proportion of the driving wheel and the turning radius of the rear virtual wheel, and then acquiring the power distribution occupation ratio of the power of the outer side wheel and the power of the inner side wheel of the driving wheel in comparison with the total output power of the driving wheel respectively according to the speeds of the outer side wheel and the inner side wheel of the driving wheel;
a power distribution module: the driving power of each driving wheel is distributed according to the power distribution ratio of the driving wheel of the electric automobile under the steering angle, so as to control the output torque of the driving motor of each driving wheel, and the electric automobile can stably run.
The method is characterized in that virtual wheels are arranged at the central points of a front shaft and a rear shaft, the turning radius is obtained through the turning angle and the wheel base, the triangular relation formed by the turning angle, the wheel base and the rear shaft is calculated by using a mathematical triangle formula, the speed ratio of an inner side wheel (generally a rear inner side wheel with the shortest distance from a junction point) and an outer side wheel is obtained through combining the wheel distance, the virtual wheels are used as the speed basis, the centrifugal power proportion is offset on the basis of the mass and the real-time speed calculation of the vehicle and the matching of the compensation speed difference, and through the arrangement, the power setting of a driving wheel and the turning speed compensation and the offset centrifugal effect are almost equal, so that a more stable driving posture is achieved.
The four-motor (four-wheel drive) is set to be constant in power distribution under the condition of full-time four-wheel drive, and power is distributed to a rear shaft or a front shaft under a certain condition by combining specific gravity of the front and rear of the weight of the vehicle body. The method specifically comprises the following steps: 1: transmitting power to a rear axle in a high speed section to obtain non-interference of driving and steering; 2: in rainy and snowy weather, the power is transmitted to the shaft with higher gravity center according to the characteristic that most of the front shaft of the automobile has higher specific gravity than the rear shaft.
Due to the adoption of the technical scheme, the invention has the following beneficial effects:
1. the invention optimizes the running of the electric automobile, solves the problem of power loss of the outer side wheel to be compensated in the running process, offsets the steering deviation caused by inertia of the automobile mass, and achieves a more stable running posture.
2. The invention enhances the stability and certain safety assistance of the driving process of double motors (front driving/rear driving) or four motors (four driving) by adjusting the power distribution in real time.
Drawings
Fig. 1 is a schematic structural view of the present invention.
FIG. 2 is a schematic diagram of the trigonometric relationship of the present invention.
Fig. 3 is a system block diagram of the present invention.
In the drawing, D is a wheel base, E is a wheel base, F is a front axle, G is a rear axle, Y is a right direction of the drawing, and Z is a left direction of the drawing.
Detailed Description
The following further describes the embodiments of the present invention with reference to the drawings.
The electric automobile is provided with a vehicle control unit, a driving controller, a steering sensor, a speed collector and the like which are connected with the vehicle control unit, and a power supply system for supplying power, wherein the speed collector is used for detecting the real-time speed of a wheel, the steering sensor is used for detecting the steering angle of the wheel, the driving controller is used for controlling the speed of the wheel driven by a hub motor (a driving motor), and the vehicle control unit is used for receiving data such as the speed, the steering angle and the like, calculating and processing the data, and then outputting power distribution instructions such as rotating speed and the like to the driving controller so as to control the power of each wheel. As will be described in detail below.
As shown in fig. 1 to 3, the dynamic stabilization system for an electric vehicle includes:
a turning radius calculation module: the system is used for defining that a front virtual wheel corresponding to the front wheel is arranged at the central point of a front shaft, a rear virtual wheel corresponding to the rear wheel is arranged at the central point of a rear shaft, and calculating to obtain a coaxial driving wheel and the turning radius of the shaft virtual wheel according to the steering angle of the electric automobile and by combining the wheel spacing of the electric automobile and the wheel base of the front wheel and the rear wheel;
the speed ratio measuring and calculating module: the speed ratio of the coaxial driving wheel of the electric automobile to the virtual wheel of the shaft is calculated and obtained according to the coaxial driving wheel of the electric automobile and the turning radius of the virtual wheel of the shaft; specifically, the ratio of the turning radius of the outer wheel and the turning radius of the inner wheel of the coaxial driving wheel to the virtual wheel of the shaft are obtained through calculation, or the ratio of the turning radius of the outer wheel and the turning radius of the inner wheel of the driving wheel to the virtual wheel of the rear shaft are obtained through calculation, and the ratios are used as the speed ratio of the outer wheel and the inner wheel of the driving wheel to the virtual wheel;
the offset ratio calculation module: the offset proportion used for offsetting the centrifugal force action of the coaxial driving wheel of the electric automobile compared with the virtual wheel of the shaft is calculated and obtained according to the mass of the electric automobile;
the wheel power ratio measuring and calculating module comprises: the power distribution ratio for superposing and offsetting the centrifugal force action of the electric automobile driving wheel on the basis of compensating the speed difference is calculated and obtained according to the turning radius, the speed ratio and the offsetting proportion of the coaxial driving wheel of the electric automobile and the turning radius of the virtual wheel of the shaft; when the electric automobile is driven by a front wheel or a rear wheel, acquiring speeds of the outer side wheel and the inner side wheel of the driving wheel respectively, which are superposed to offset the action of centrifugal force on the basis of compensating speed difference compared with the virtual wheel of the shaft, according to the turning radius, the speed ratio and the offset ratio of the coaxial driving wheel and the turning radius of the virtual wheel of the shaft, and then acquiring the power distribution ratio of the power of the outer side wheel and the power of the inner side wheel of the driving wheel compared with the total output power of the driving wheel respectively according to the speeds of the outer side wheel and the inner side wheel of the driving wheel; when the electric automobile is driven by four wheels, acquiring speeds of the outer side wheel and the inner side wheel of the driving wheel respectively in comparison with the rear virtual wheel on the basis of compensating speed difference by superposing and offsetting centrifugal force action according to the turning radius, the speed occupation ratio and the offsetting proportion of the driving wheel and the turning radius of the rear virtual wheel, and then acquiring the power distribution occupation ratio of the power of the outer side wheel and the power of the inner side wheel of the driving wheel in comparison with the total output power of the driving wheel respectively according to the speeds of the outer side wheel and the inner side wheel of the driving wheel;
a power distribution module: the driving power of each driving wheel is distributed according to the power distribution ratio of the driving wheel of the electric automobile under the steering angle, so as to control the output torque of the driving motor of each driving wheel, and the electric automobile can stably run.
Referring to fig. 1 and 2, the following will specifically describe the processing procedure:
the method comprises the steps of firstly, defining a front virtual wheel corresponding to a front wheel at the position of the front virtual wheel, and a rear virtual wheel corresponding to a rear wheel at the position of the rear virtual wheel, and calculating to obtain a coaxial driving wheel (the front wheel and/or the rear wheel) and the turning radius of the axial virtual wheel (the front virtual wheel and/or the rear virtual wheel) according to the steering angle of the electric vehicle and by combining the wheel spacing of the electric vehicle and the wheel base of the front wheel and the rear wheel. The steering sensor detects and obtains the steering angle, and the vehicle control unit receives the steering angle and then processes according to a preset program.
When the electric automobile turns, the front wheels are steered by a steering angle of & lt A, the front wheels are steered by the steering angle of & lt A, the extension line of the middle shaft of the front virtual wheel B and the extension line of the middle shaft of the rear inner side wheel C2 are converged at a point O, and the convergence point O is the steering center of the steering angle. The rear outer wheel C1, the rear inner wheel C2, the front outer wheel C3, the front inner wheel C4, the front virtual wheel B, and the rear virtual wheel B1 may form a triangular relationship with the intersection point O. An included angle between the front outer side wheel and the junction point as well as between the rear outer side wheel and the junction point as angle C3OC1 is angle 1, an included angle between the front virtual wheel and the junction point as well as between the rear virtual wheel and the junction point as angle BOB1 is angle 2, and an included angle between the front inner side wheel and the junction point as well as between the rear inner side wheel and the junction point as angle C4OC2 is angle 3. The following description will be given by taking a case where no rear wheel is steered as an example, and at this time, the angle C4C2O is a right angle. Referring to fig. 1 and 2, the following is detailed:
distance R from intersection point O to center point of front axle B I.e. the turning radius, R, of the front virtual wheel B B ＝D÷sin∠2；
Distance R from intersection point O to center of front inner side wheel middle shaft C4 I.e. the turning radius, R, of the front inner side wheel C4 C4 ＝D÷sin∠3；
Distance R from intersection point O to center of front outer side wheel middle shaft C3 I.e. the turning radius, R, of the front outer wheel C3 C4 ＝D÷sin∠1；
Distance R from intersection point O to central point of rear axle B1 I.e. the turning radius, R, of the rear virtual wheel B1 B1 ＝D*cot∠2；
Distance R from intersection point O to center of middle axle of rear inner side wheel C2 Namely the turning radius of the rear inner side wheel C2,
distance R from intersection point O to center of middle axle of rear outer side wheel C1 I.e. the turning radius of the rear outside wheel C1,
wherein < 2= < a,
d is the wheel base of the front wheel and the rear wheel, and E is the wheel spacing of the rear wheel. The scheme of the invention is suitable for the steering angle A of the front wheel to be more than 0 degree and less than 90 degrees.
And secondly, calculating the speed ratio of the coaxial driving wheel of the electric automobile to the virtual wheel of the shaft according to the coaxial driving wheel of the electric automobile and the turning radius of the virtual wheel of the shaft. Calculating to obtain the ratio of the turning radius of the outer side wheel and the turning radius of the inner side wheel of the coaxial driving wheel to the virtual wheel of the shaft respectively, or calculating to obtain the ratio of the turning radius of the outer side wheel and the turning radius of the inner side wheel of the driving wheel to the virtual wheel of the rear shaft respectively, and taking the ratio as the speed ratio of the outer side wheel and the inner side wheel of the driving wheel to the virtual wheel respectively; specifically, when the electric automobile is driven by a front wheel or a rear wheel, calculating to obtain the ratio of the turning radius difference of the coaxial outer side wheel and the coaxial inner side wheel to the turning radius of the virtual wheel of the shaft, and respectively taking the ratio as the speed ratio of the coaxial outer side wheel and the coaxial inner side wheel to the virtual wheel of the shaft; and when the electric automobile is in four-wheel drive, obtaining the turning radius of each wheel and the virtual wheel, wherein the ratio of the turning radius of each wheel to the turning radius of the coaxial virtual wheel is respectively used as the speed ratio of each wheel to the axle virtual wheel.
Under the condition that the front wheels are in charge of steering and the rear wheels are not in steering, the intersection point O of the middle shaft extension line of the front virtual wheel B of the front shaft and the middle shaft extension line of the rear shaft is used as the turning reference of the vehicle, and the speed of the four wheels is the speed difference formed by taking the intersection point O as the reference during steering. And the speed v of the coaxial outer wheel Outer cover With speed v of its inner wheels Inner part In different, combining with the arc length calculation formula, v can be obtained Outer cover /v Inner part ＝R Outer cover /R Inner part If the radius is known, the speed of one wheel can be calculated from the speed of the other wheel on the same axis. Calculating to obtain a ratio of the speed of the front outer side wheel and the speed of the front inner side wheel relative to the preset wheel B when the electric automobile is in the front driving state; when the electric automobile is driven backwards, the speed of the rear outer side wheel and the speed of the rear inner side wheel relative to the preset rear shaft virtual wheel B1 respectively obtain a ratio; when the electric automobile is driven four times, the speed of the four driving wheels relative to the rear virtual wheel B1 respectively obtains a ratio. Wherein the specific speedThe calculation formula of the degree ratio is as follows:
speed ratio of front outer wheel to front virtual wheel
Speed ratio of front inner side wheel to front virtual wheel
Speed ratio of rear outer wheel to rear virtual wheel
Speed ratio of rear inner side wheel to rear virtual wheel
Speed ratio of front outer wheels to rear virtual wheels
Speed ratio of front inner side wheel to rear virtual wheel
And thirdly, calculating and obtaining the offset ratio of the coaxial driving wheel of the electric automobile to the virtual wheel of the shaft for offsetting the centrifugal force according to the mass of the electric automobile.
Due to inertia, when an automobile is driven and steered at a certain speed, a centrifugal force acts on the automobile, if the automobile is not steered sufficiently, the automobile may rush out of a road surface due to the centrifugal force, if the automobile is steered excessively, the automobile may turn over outwards due to the centrifugal force, so that the automobile is separated from a steering angle, and an unpredictable driving track is caused.
Of course, because someone sits on the car, or loads goods, at this moment, the quality of electric automobile should also be counted into with all loads such as passenger except including electric automobile body quality, can estimate the load in advance or detect seat and trunk weight through pressure sensor or weight sensor etc. and in order to obtain the load to obtain more accurate total mass, and then obtain more according with actual offset ratio through setting up total mass and preset relational expression. This step can also precede the first two steps.
Fourthly, calculating to obtain a power distribution ratio of the electric automobile driving wheel on the basis of compensating the speed difference by superposing the action of offsetting the centrifugal force according to the turning radius, the speed ratio and the offsetting ratio of the coaxial driving wheel of the electric automobile and the turning radius of the central point of the shaft; when the electric automobile is driven by a front wheel or a rear wheel, the speeds of the outer side wheel and the inner side wheel of the driving wheel which are superposed and offset the action of centrifugal force on the basis of compensating speed difference compared with the central point of the shaft are obtained according to the turning radius, the speed ratio and the offset ratio of the coaxial driving wheel and the turning radius of the central point of the shaft (namely, the value of the offset ratio is added to the outer side wheel of the driving wheel to offset the centrifugal force, and the value of the equal offset ratio is subtracted from the inner side wheel of the outer side wheel in the form of a balance value); when the electric automobile is driven by four wheels, the speeds of the outer side wheel and the inner side wheel of the driving wheel respectively, which are superposed to offset the action of centrifugal force on the rear virtual wheel on the basis of compensating the speed difference, are obtained according to the turning radius, the speed ratio and the offset ratio of the driving wheel and the turning radius of the rear virtual wheel, and then the power distribution ratio of the power of the outer side wheel and the power of the inner side wheel of the driving wheel respectively, which is compared with the total output power of the driving wheel, is obtained according to the speeds of the outer side wheel and the inner side wheel of the driving wheel.
As described above, the driving wheels compensate for the speed difference and input a ratio in combination with the vehicle body mass and the speed to offset the centrifugal force, and although the speeds of the front and rear wheels are not uniform, the input ratio is uniform with respect to the speeds of the center points of the respective front and rear axles in order to offset the centrifugal force.
In the invention, the offsetting centrifugal force is divided into two parts, the first part is the value of the offsetting ratio added to the outer wheel, and the value of the equal offsetting ratio is subtracted from the inner wheel in a balance value mode to offset the centrifugal force; through setting up certain power and offsetting the ratio for each drive wheel is according to certain power ratio operation, with distribution driving motor output torque, forces outside wheel speed increase and the corresponding reduction of inside wheel speed, forms a deflection moment, with offsetting centrifugal force, makes the car turn to according to predetermineeing the direction and travel. That is, the power distribution thereof can be actually calculated for each drive wheel speed ratio, and therefore, the calculation formula of the drive wheel power distribution ratio is as follows:
when the electric automobile is driven by the front wheel, the speed of the front virtual wheel is v, and the speed of the front outer side wheel is v under the condition of superposing and offsetting centrifugal force on the basis of compensating speed difference C3 ＝v*i 1 +v*i 1 * k, front inner wheel speed v C4 ＝v*i 2 -v*i 2 * k, and obtaining the speed ratio v of the front outer wheel to the front inner wheel C3 ：v C4 I.e., its power ratio, so that the power split ratio of the front outer wheels is q 13 ＝v C3 ÷(v C3 +v C4 )*100％＝(i 1 +i 1 *k)÷(i 1 +i 1 *k+i 2 -i 2 * k) 100%, the power distribution ratio of the front inner side wheel is q 14 ＝v C4 ÷(v C3 +v C4 )*100％＝(i 2 -i 2 *k)÷(i 1 +i 1 *k+i 2 -i 2 *k)*100％；
When the electric automobile is driven by the rear wheel, the speed of the rear virtual wheel is v 1 The speed v of the rear outer wheel is superposed and offset under the action of centrifugal force on the basis of compensating the speed difference C1 ＝v 1 *j 1 +v 1 *j 1 * k, rear inner wheel speed v C2 ＝v 1 *j 2 -v 1 *j 2 * k, and obtaining the speed ratio v of the rear outer wheel to the rear inner wheel C1 ：v C2 I.e., its power ratio, so that the power distribution ratio of the rear outer wheel is q 21 ＝v C1 ÷(v C1 +v C2 ) 100%, the power distribution ratio of the rear inner side wheel is q 22 ＝v C2 ÷(v C1 +v C2 )*100％。
When the electric automobile is in four-wheel drive, the rear virtual wheel speed is v 2 The speed of the front and the outer wheel is v under the condition of superposing and offsetting the centrifugal force on the basis of compensating the speed difference C3 ＝v 2 *j 3 +v 2 *j 3 * k, front inner wheel speed v C4 ＝v 2 *j 4 -v 2 *j 4 * k, rear outboard wheel speed v C1 ＝v 2 *j 1 +v 2 *j 1 * k, rear inner wheel speed v C2 ＝v 2 *j 2 -v 2 *j 2 * k; thereby obtaining the speed ratio v of the four wheels C1 ：v C2 ：v C3 ：v C4 I.e., its power ratio, so that the front-outer wheel power distribution ratio is q 33 ＝v C3 ÷(v C1 +v C2 +v C3 +v C4 ) 100% and the power distribution ratio of the front inner side wheel is q 34 ＝v C4 ÷(v C1 +v C2 +v C3 +v C4 ) 100% of power distribution of rear outer wheel of q 31 ＝v C1 ÷(v C1 +v C2 +v C3 +v C4 ) 100% of power distribution of rear inner side wheel 32 ＝v C2 ÷(v C1 +v C2 +v C3 +v C4 )*100％。
Wherein k is a dynamic offset ratio for offsetting the action of the centrifugal force.
And fifthly, distributing the driving power of each driving wheel according to the power distribution ratio of the driving wheel of the electric automobile under the steering angle so as to control the output torque of the driving motor of each driving wheel and control the rotating speed of each driving wheel, so that the electric automobile stably runs.
As described above, under the forward driving, the backward driving or the four-wheel driving, the speed specific gravity relation of each driving wheel can be obtained, and the power distribution ratio of each driving wheel under the steering angle can be obtained; and then, based on the power distribution ratio, converting the total driving power input by the driver into the driving power component of each driving wheel to finish the driving power ratio process. The whole vehicle controller converts the electric energy output quantity of each driving wheel and then sends an instruction to the driving controller, and the driving controller controls the output torque of the electric energy to the hub motors of the front wheels and the rear wheels, so that the rotating speed of the corresponding wheels is controlled, a centripetal force is formed, and the electric vehicle can stably steer.
The specific parameters for calculating the driving wheel speed of the electric automobile are as follows: assuming that D =2600mm, e =1600mm, k =0.05 and the front wheels are steered at ≈ a =30 ° in the Y direction, since ≈ OC2C4 is a right angle when the rear wheels are not steered, so = 3= a =30 °, the calculation is performed by combining the above formulas. Selecting front wheel drive, rear wheel drive or four wheel drive, calculating according to corresponding turning radius, and obtaining turning radius of front wheel and rear wheel by using Pythagorean theorem C4 ＝4524.8943mm，R C3 ＝5906.3606mm，R B ＝5200.0000mm，R C1 ＝5303.3321mm，R C2 ＝3703.3321mm，R B1 =4503.3321mm. And then according to the selected front driving, rear driving or four-wheel driving, calculating to obtain the speed ratio i of the front wheels and the rear wheels under the condition of meeting the compensation condition 1 、i 2 、j 1 And j 2 Etc.; further obtaining the speed v of the front driving wheel after the action of the centrifugal force is superposed and offset C3 And v C4 Or rear-drive wheel speed v C1 And v C1 Or four wheel speeds. Further, obtaining a power ratio; for example, when the front wheels are driven forwards, the power of the front outer side wheel accounts for 59.0618 percent, and the power of the front inner side wheel accounts for 40.9382 percent; in the case of rear drive, the power of the rear outer wheel accounts for 61.2821%, and the power of the rear inner wheel accounts for 38.7179%. Wherein angle 1 is less than 26.7 DEG and angle 3 is less than 35.4 deg. Moreover, only some of the parameter calculation results are given here, and some of the results are divisors, and other values can be calculated by referring to the specific calculation formula mentioned above.
As an option, in an example, the system further includes a training matching module, configured to set a series of values of steering angle parameters of the electric vehicle, and train a series of power distribution ratios of each driving wheel; and when the electric automobile runs, according to the steering angle of the electric automobile, directly matching and relating the corresponding power distribution ratio under the steering angle, so that the power distribution module distributes driving power according to the power distribution relation of each driving wheel, so as to control the output torque of the driving motor of each driving wheel, control the rotating speed of each driving wheel and enable the electric automobile to run stably. The power distribution relation is the ratio of the total driving power of each driving wheel to the input power, and the power distribution relation is directly converted into the driving power of each driving vehicle on the basis of the steering angle and the total driving power. The method comprises the following specific steps:
the method comprises the steps that a vehicle is set to run at a speed v0, steering is carried out at a speed of & lt A0, at the moment, the power distribution relation of each driving wheel can be calculated, stable steering is carried out, then training is repeated at a steering angle increment of & lt A1, the power distribution relation of the wheels during steering at & lt A0+ n & lt A1 is obtained, and the power distribution relation is stored after simplification; then, while driving, the corresponding power distribution ratio distribution is substituted in direct response to the steering angle. Therefore, when the automobile steers, the real-time processing program is reduced, the output rate of the operation processing is enhanced, and the automobile is more stably steered.
Of course, under the condition of known vehicle wheelbase, wheel spacing, front wheel steering, rear wheel steering or all-wheel steering, a program can be directly built in the speed collector, and parameters such as the speed difference of the wheel on the outer side and the wheel on the inner side can be directly calculated.
As described above, in a stable driving scene, the driving power is distributed, the speed difference is optimally compensated, the steering deviation caused by inertia of the mass of the automobile is offset, and a more stable driving posture is achieved. Certainly, under the scene of high driving pleasure, the power of the driving wheel can be set to exceed the action of turning speed compensation and centrifugal force offset, appropriate over-steering is achieved, certain drift is formed, and the driving pleasure can be improved.
The above description is intended to describe in detail the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the claims of the present invention, and all equivalent changes and modifications made within the technical spirit of the present invention should fall within the scope of the claims of the present invention.
Claims (6)
1. An electric vehicle dynamic stabilization system, comprising:
a turning radius calculation module: the system is used for defining that a front virtual wheel corresponding to the front wheel is arranged at the central point of a front shaft, a rear virtual wheel corresponding to the rear wheel is arranged at the central point of a rear shaft, and calculating to obtain a coaxial driving wheel and the turning radius of the shaft virtual wheel according to the steering angle of the electric automobile and by combining the wheel spacing of the electric automobile and the wheel base of the front wheel and the rear wheel;
the speed ratio measuring and calculating module: the speed ratio of the coaxial driving wheel of the electric automobile to the virtual wheel of the shaft is calculated and obtained according to the coaxial driving wheel of the electric automobile and the turning radius of the virtual wheel of the shaft; specifically, the ratio of the turning radius of the outer side wheel and the turning radius of the inner side wheel of the coaxial driving wheel to the virtual wheel of the shaft is calculated and obtained, or the ratio of the turning radius of the outer side wheel and the turning radius of the inner side wheel of the driving wheel to the virtual wheel of the rear shaft is calculated and obtained, and the ratio is used as the speed ratio of the outer side wheel and the inner side wheel of the driving wheel to the virtual wheel;
the offset ratio calculation module: the offset proportion used for offsetting the centrifugal force action of the coaxial driving wheel of the electric automobile compared with the virtual wheel of the shaft is calculated and obtained according to the mass of the electric automobile;
the wheel power ratio measuring and calculating module comprises: the power distribution ratio for superposing and offsetting the centrifugal force action of the electric automobile driving wheel on the basis of compensating the speed difference is calculated and obtained according to the turning radius, the speed ratio and the offsetting proportion of the coaxial driving wheel of the electric automobile and the turning radius of the virtual wheel of the shaft;
a power distribution module: the driving power of each driving wheel is distributed according to the power distribution ratio of the driving wheel of the electric automobile under the steering angle, so as to control the output torque of the driving motor of each driving wheel, and the electric automobile can stably run.
2. The dynamic stabilization system of the electric vehicle of claim 1, wherein: the wheel power ratio measuring and calculating module comprises the following specific contents:
when the electric automobile is driven by a front wheel or a rear wheel, acquiring speeds of the outer side wheel and the inner side wheel of the driving wheel respectively, which are superposed to offset the action of centrifugal force on the basis of compensating speed difference compared with the virtual wheel of the shaft, according to the turning radius, the speed ratio and the offset ratio of the coaxial driving wheel and the turning radius of the virtual wheel of the shaft, and then acquiring the power distribution ratio of the power of the outer side wheel and the power of the inner side wheel of the driving wheel compared with the total output power of the driving wheel respectively according to the speeds of the outer side wheel and the inner side wheel of the driving wheel;
when the electric automobile is driven by four wheels, the speeds of the outer side wheel and the inner side wheel of the driving wheel respectively, which are superposed to offset the action of centrifugal force on the rear virtual wheel on the basis of compensating the speed difference, are obtained according to the turning radius, the speed ratio and the offset ratio of the driving wheel and the turning radius of the rear virtual wheel, and then the power distribution ratio of the power of the outer side wheel and the power of the inner side wheel of the driving wheel respectively, which is compared with the total output power of the driving wheel, is obtained according to the speeds of the outer side wheel and the inner side wheel of the driving wheel.
3. The dynamic stabilization system of an electric vehicle of claim 2, wherein: in the wheel power ratio measuring and calculating module, the turning radius of the front virtual wheel is R B The rear virtual wheel has a turning radius R B1 ，R C4 The turning radius of the front inner side wheel, R C3 Radius of front outer wheel turning, R C2 The turning radius of the rear inner side wheel, R C1 For the rear outer wheel turning radius, the calculation process of the power distribution ratio of each driving wheel is as follows:
when the electric automobile is driven by the front wheel, the speed of the front virtual wheel is v, and the speed of the front outer side wheel is v under the condition of superposing and offsetting centrifugal force on the basis of compensating speed difference C3 ＝v*i 1 +v*i 1 * k, front inner wheel speed v C4 ＝v*i 2 -v*i 2 * k, so that the power distribution ratio of the front outer wheels is q 13 ＝v C3 ÷(v C3 +v C4 ) 100%, the power distribution ratio of the front inner side wheel is q 14 ＝v C4 ÷(v C3 +v C4 )*100％；
When the electric automobile is driven by the rear wheel, the speed of the rear virtual wheel is v 1 The speed v of the rear outer wheel is superposed and offset under the action of centrifugal force on the basis of compensating the speed difference C1 ＝v 1 *j 1 +v 1 *j 1 * k, rear inner wheel speed v C2 ＝v 1 *j 2 -v 1 *j 2 * k, so that the power distribution ratio of the rear outer wheel is q 21 ＝v C1 ÷(v C1 +v C2 ) 100%, the power distribution ratio of the rear inner side wheel is q 22 ＝v C2 ÷(v C1 +v C2 )*100％；
When the electric automobile is in four-wheel drive, the rear virtual wheel speed is v 2 The speed of the front and the outer wheel is v under the condition of superposing and offsetting the centrifugal force on the basis of compensating the speed difference C3 ＝v 2 *j 3 +v 2 *j 3 * k, front inner wheel speed v C4 ＝v 2 *j 4 -v 2 *j 4 * k, rear outboard wheel speed v C1 ＝v 2 *j 1 +v 2 *j 1 * k, rear inner wheel speed v C2 ＝v 2 *j 2 -v 2 *j 2 * k; thus, the power distribution ratio of the front outer wheel is q 33 ＝v C3 ÷(v C1 +v C2 +v C3 +v C4 ) 100% and the power distribution ratio of the front inner side wheel is q 34 ＝v C4 ÷(v C1 +v C2 +v C3 +v C4 ) 100% of power distribution of rear outer wheel of q 31 ＝v C1 ÷(v C1 +v C2 +v C3 +v C4 ) 100% of power distribution of rear inner side wheel 32 ＝v C2 ÷(v C1 +v C2 +v C3 +v C4 )*100％；
Wherein k is a counteracting proportion of the power counteracting the centrifugal force; speed ratio of front outer wheel to front virtual wheel
Speed ratio of front inner wheel to front virtual wheel
Speed ratio of rear outer wheel to rear virtual wheel
Speed ratio of rear inner side wheel to rear virtual wheel
Ratio of speed of front outer wheel to rear virtual wheel
Speed ratio of front inner side wheel to rear virtual wheel
4. The dynamic stabilization system of the electric vehicle of claim 3, wherein: the turning radius of the front wheels and the rear wheels is calculated as follows:
when the electric automobile turns, the front wheel is steered by a steering angle of & lt A & gt, the intersection of the extension line of the middle shaft of the front virtual wheel B and the extension line of the middle shaft of the rear inner side wheel C2 is at a point O, the intersection point O is a steering center of the steering angle, the included angles & lt C3OC1 between the front outer side wheel and the rear outer side wheel and a junction are & lt 1 & gt, the included angles & lt BOB1 between the front virtual wheel and the rear virtual wheel and the junction are & lt 2 & gt, the included angles & lt C4OC2 between the front inner side wheel and the rear inner side wheel and the junction are & lt 3 & gt, wherein & lt C4C2O is a right angle under the condition that the rear wheel is not steered;
distance R from intersection point O to center point of front axle B I.e. the turning radius, R, of the front virtual wheel B B ＝D÷sin∠2；
Distance R from intersection point O to center of middle shaft of front inner side wheel C4 I.e. the turning radius, R, of the front inner side wheel C4 C4 ＝D÷sin∠3；
Distance R from intersection point O to center of front outer side wheel middle shaft C3 I.e. the turning radius, R, of the front outer wheel C3 C4 ＝D÷sin∠1；
Distance R from intersection point O to central point of rear axle B1 I.e. the turning radius, R, of the rear virtual wheel B1 B1 ＝D*cot∠2；
Distance R from intersection point O to center of middle shaft of rear inner side wheel C2 Namely the turning radius of the rear inner side wheel C2,
distance R from intersection point O to center of middle axle of rear outer side wheel C1 I.e. the turning radius of the rear outside wheel C1,
wherein < 2= < a,
d is the wheelbase of the front wheel and the rear wheel, and E is the wheelbase of the rear wheel.
5. The dynamic stabilization system of the electric vehicle of claim 4, wherein: the steering angle & lt A of the front inner side wheels is more than 0 degree and less than 90 degrees.
6. The dynamic stabilization system of an electric vehicle of claim 1, wherein: the system also comprises a training matching module, a driving module and a driving module, wherein the training matching module is used for setting a series of steering angle parameter values of the electric automobile and correspondingly training a series of power distribution ratio of each driving wheel; and when the electric automobile runs, directly matching and associating the corresponding power distribution ratio according to the steering angle of the electric automobile, so that the power distribution module distributes driving power according to the power distribution ratio of each driving wheel to control the output torque of the driving motor of each driving wheel, and the electric automobile runs stably.
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