Cruise control method and system for pure electric vehicle based on constant-effect cruise

Abstract

The invention relates to the technical field of cruise mode control strategies, in particular to a cruise control method and system for a pure electric vehicle based on definite-effect cruise, and the cruise control method for the pure electric vehicle comprises the steps: obtaining a motor efficiency torque Map map and a preset target efficiency value, determining a target efficiency curve, and calculating a running resistance curve of the vehicle in real time; target efficiency torque is calculated according to the current motor rotating speed and the target efficiency curve, current driving resistance is calculated according to the current motor rotating speed and the driving resistance curve, and the current motor torque is adjusted to be the target efficiency torque; a cruise mode is determined according to the magnitude relation between the target efficiency torque and the current driving resistance and the current vehicle speed u, the motor torque is adjusted in real time according to the cruise mode, and the cruise mode comprises a constant-speed cruise mode and a constant-effect cruise mode. According to the invention, the vehicle is allowed to adaptively adjust the torque in a certain speed interval, and the motor always works in a set higher efficiency range in the speed interval, so that the effects of reducing the power consumption and improving the endurance are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of cruise mode control strategies, and in particular to a cruise control method and system for a pure electric vehicle based on fixed-effect cruise control. Background Art

[0002] The vehicle cruise function can effectively reduce the driver's fatigue during long-distance driving and improve driving safety. At present, the cruise mode of pure electric commercial vehicles mainly adopts constant speed endurance, and the set endurance range is generally 40-90km / h. When the vehicle enters the cruise mode, the current speed will be used as the target speed. As the road conditions change, the vehicle controller will collect road resistance information to dynamically control the drive motor. If the speed decreases, the controller will increase the motor torque. If the speed increases, the controller will reduce the motor torque to maintain a constant speed.

[0003] The torque output of cruise control is completely determined by the road resistance. During long-distance driving, the road conditions are constantly changing, and the road resistance will also fluctuate. In order to respond to the changing resistance and maintain the vehicle at a constant speed, the vehicle controller will control the motor torque to change accordingly. The efficiency of the motor is directly related to the motor speed and torque, and is stored in the controller, as shown in the following table:

[0004]

[0005] Therefore, in cruise control mode, changes in motor torque will also cause large fluctuations in motor efficiency. In addition, commercial vehicle drivers generally cruise at extremely high speeds, and motor efficiency will drop significantly at high speeds. In this way, the vehicle will travel in a lower motor efficiency range, resulting in increased vehicle power consumption and significantly reduced endurance. Summary of the invention

[0006] The purpose of the present invention is to address the defects of the prior art and to provide a cruise control method and system for pure electric vehicles based on fixed-efficiency cruise control. The method and system comprehensively analyze and automatically adjust the motor torque and efficiency according to the motor characteristics and objective road factors. By coordinating vehicle-road information, the vehicle is allowed to adaptively adjust the torque within a certain speed range under high-speed conditions or cruising conditions. Within this speed range, the motor always operates within a set higher efficiency range, thereby reducing power consumption and improving endurance while reducing the driver's driving intensity.

[0007] In order to solve the above technical problems, in a first aspect, the present invention provides a cruise control method for a pure electric vehicle based on fixed-efficiency cruise control, comprising:

[0008] Obtain the motor efficiency torque map and preset target efficiency value, determine the target efficiency curve, and calculate the vehicle's driving resistance curve in real time;

[0009] Calculate the target efficiency torque according to the current motor speed and the target efficiency curve, calculate the current driving resistance according to the current motor speed and the driving resistance curve, and adjust the current motor torque to the target efficiency torque;

[0010] The cruise mode is determined based on the relationship between the target efficiency torque and the current driving resistance and the current vehicle speed u, and the motor torque is adjusted in real time according to the cruise mode. The current vehicle speed u is calculated based on the current motor speed. The cruise mode includes a constant-speed cruise mode and a constant-efficiency cruise mode. The constant-speed cruise mode maintains the current speed, and the constant-efficiency cruise mode keeps the motor efficiency always not less than the target efficiency value.

[0011] Furthermore, the method for calculating the target efficiency torque includes: calculating the motor torque corresponding to the target efficiency curve according to the current motor speed; if there are two motor torques corresponding to the target efficiency curve, namely T1 and T2, the smaller value of T1 and T2 is used as the target efficiency torque; if there is only one motor torque corresponding to the target efficiency curve, it is directly used as the target efficiency torque.

[0012] Furthermore, the method for adjusting the motor torque in real time includes: if u l ≤u<u h , and the target efficiency torque is greater than the current driving resistance, the cruise mode is determined to be the fixed efficiency cruise mode, and the motor torque is adjusted along the target efficiency curve so that the vehicle speed gradually increases until the motor torque is equal to the driving resistance;

[0013] Among them, u l is the minimum speed in the speed range corresponding to the target efficiency curve, u h is the maximum speed in the speed range corresponding to the target efficiency curve.

[0014] Furthermore, the method for adjusting the motor torque in real time includes: if u l <u≤u h , and the target efficiency torque is less than the current driving resistance, the cruise mode is determined to be the fixed-efficiency cruise mode, and the motor torque is adjusted along the target efficiency curve so that the vehicle speed gradually decreases until the target efficiency torque is equal to the driving resistance.

[0015] Furthermore, the method for adjusting the motor torque in real time includes: if u=u h , and the target efficiency torque is greater than the current driving resistance, the cruise mode is determined to be the fixed speed cruise mode, and the current vehicle speed u is maintained. h , adjust the motor torque in real time so that the motor torque is always equal to the driving resistance.

[0016] Furthermore, the method for adjusting the motor torque in real time includes: if u=u l, and the target efficiency torque is less than the current driving resistance, the cruise mode is determined to be the fixed speed cruise mode, and the current vehicle speed u is maintained. l , adjust the motor torque in real time so that the motor torque is always equal to the driving resistance.

[0017] Furthermore, in the process of adjusting the motor torque in real time, the maximum output torque of the battery is calculated, and the required torque of the vehicle is compared with the maximum output torque of the battery, so that the required torque of the vehicle is always not greater than the maximum output torque of the battery.

[0018] In a second aspect, the present invention provides a pure electric vehicle cruise control system based on fixed-efficiency cruise control, comprising:

[0019] The signal acquisition and processing module is used to obtain the target efficiency value and determine the target efficiency curve, collect the current motor speed in real time, and calculate the driving resistance curve, target efficiency torque, driving resistance, and current vehicle speed in real time;

[0020] A judgment module, used to determine the current cruise mode according to the current vehicle speed, target efficiency torque, and driving resistance;

[0021] A control module is used to adjust the motor torque according to the current cruise mode.

[0022] In a third aspect, the present invention provides a non-transitory computer-readable storage medium for storing a computer program or instruction. When the computer program or instruction is executed by a computer, the pure electric vehicle cruise control method based on fixed-efficiency cruise control is implemented.

[0023] In a fourth aspect, the present invention provides a computer program product, which includes computer instructions; when part or all of the computer instructions are run on a computer, the pure electric vehicle cruise control method based on fixed-efficiency cruise control is executed.

[0024] The beneficial effects of the present invention are as follows: the present invention comprehensively analyzes and automatically adjusts the motor torque and efficiency according to the motor characteristics and objective road factors, and allows the vehicle to adaptively adjust the torque within a certain speed range under high-speed conditions or cruising conditions by coordinating vehicle-road information. Within this speed range, the motor always works within the set higher efficiency range, and the effect of reducing power consumption and improving endurance is achieved while reducing the driver's driving intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a control flow chart of the present invention;

[0026] Figure 2 is the target efficiency curve diagram of the present invention;

[0027] Figure 3 is a running resistance curve diagram of the present invention;

[0028] Figure 4 This is a diagram of the motor efficiency analysis of the present invention;

[0029] Figure 5 For the present invention l ≤u<u h And the motor torque adjustment diagram when the target efficiency torque is greater than the current driving resistance;

[0030] Figure 6 For the present invention l <u≤u h And the motor torque adjustment diagram when the target efficiency torque is less than the current driving resistance;

[0031] Figure 7 For the present invention, u=u h And the motor torque adjustment diagram when the target efficiency torque is greater than the current driving resistance;

[0032] Figure 8 For the present invention, u=u l And the motor torque adjustment diagram when the target efficiency torque is less than the current driving resistance;

[0033] Fig. 9 It is the control principle diagram of the PID controller model of the present invention. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0035] The vehicle cruise control does not consider the economical problem. In order to improve the motor efficiency, the motor efficiency value can be set according to the motor efficiency torque map. According to the target efficiency value, the minimum speed range [nl, nh] is determined, such as Figure 2 As shown in the figure, the minimum speed range is used to prevent the cruising speed from fluctuating too much. l is the minimum speed in the speed range corresponding to the target efficiency curve, n h is the maximum speed in the speed range corresponding to the target efficiency curve.

[0036] According to the vehicle dynamics equation, the vehicle's driving resistance F under the current road conditions can be calculated. 阻 , the formula is as follows:

[0037] FF resistance = F + Fw + Fa + Fi

[0038] Where, Ff is the rolling resistance, Ff=mgf, m is the mass of the vehicle, g is the acceleration of gravity, and f is the rolling resistance coefficient;

[0039] Fw is the air resistance of the vehicle, C D is the drag coefficient, A is the frontal area;

[0040] F a is the acceleration resistance, F a =ma, a is the acceleration of the vehicle;

[0041] Fi is the slope resistance, Fi=mgsinα, α is the road slope.

[0042] According to the above formula, the air resistance is exponentially related to the vehicle speed u. Therefore, the driving resistance curve of the whole vehicle on the same road surface is as follows: Figure 3 shown.

[0043] like Figure 1 As shown, the present invention provides a cruise control method for a pure electric vehicle based on fixed-efficiency cruise control, comprising:

[0044] The vehicle can enter the cruise mode when the vehicle speed is within the cruise mode operating range. The vehicle speed u is calculated based on the current motor speed n. r is the wheel radius, i g is the transmission ratio of the gearbox in the current gear (1 if there is no gearbox), i0 is the transmission ratio of the main reducer; when u l ≤u≤u h , it is determined that the vehicle speed is within the cruise mode operating range.

[0045] After entering the cruise mode, the motor efficiency torque map and the preset target efficiency value are obtained, the target efficiency curve is determined, and the vehicle's driving resistance curve is calculated in real time;

[0046] The target efficiency torque is calculated according to the current motor speed and the target efficiency curve; the method for calculating the target efficiency torque includes: calculating the motor torque corresponding to the target efficiency curve according to the current motor speed; if there are two motor torques corresponding to the target efficiency curve, namely T1 and T2, the smaller value of T1 and T2 is used as the target efficiency torque; if there is only one motor torque corresponding to the target efficiency curve, it is directly used as the target efficiency torque.

[0047] It should be noted that according to the calculation formula of motor power T is torque, n is speed, it can be seen that the area enclosed by the torque curve and the coordinate axis in the torque map of the motor is proportional to the motor power. Therefore, the steady speed point is the balance point where the motor torque is equal to the driving resistance. The steady speed point at the lower end of the efficiency curve consumes less electric energy, such as Figure 4As shown in the figure, area ① is obviously smaller than area ②, so the lower steady-speed point should be taken as the final steady-speed point. Therefore, when calculating the target efficiency torque, the lower target efficiency torque should be taken as the steady-speed point to ensure that the motor efficiency is smaller.

[0048] Calculate the current driving resistance according to the current motor speed and the driving resistance curve, and adjust the current motor torque to the target efficiency torque;

[0049] The cruise mode is determined based on the relationship between the target efficiency torque and the current driving resistance and the current vehicle speed u, and the motor torque is adjusted in real time according to the cruise mode.

[0050] Among them, the cruise mode includes a constant speed cruise mode and a constant efficiency cruise mode. The constant speed cruise mode is to maintain the current speed, and the constant efficiency cruise mode is to keep the motor efficiency always not less than the target efficiency value.

[0051] Methods for adjusting motor torque in real time include:

[0052] like Figure 5 As shown, if u l ≤u<u h , and the target efficiency torque is greater than the current driving resistance, that is, the driving resistance is below the target efficiency curve, then the cruise mode is determined to be the fixed efficiency cruise mode, and the motor torque is adjusted along the target efficiency curve so that the vehicle speed gradually increases until the motor torque is equal to the driving resistance, that is, the motor torque is along the Figure 5 It should be noted that during the adjustment process, if the motor torque is always greater than the driving resistance, the vehicle speed will gradually increase, and the increase in vehicle speed will lead to an increase in driving resistance, that is, the curvature of the driving resistance curve will increase. Therefore, the intersection of the driving resistance curve and the target efficiency curve will move in the opposite direction of the arrow until the motor speed reaches a certain value, and the motor torque is equal to the driving resistance. Figure 5 The change of the driving resistance curve is not shown in the figure, it is only used as a schematic diagram of the motor torque adjustment.

[0053] like Figure 6 As shown, if u l <u≤u h , and the target efficiency torque is less than the current driving resistance, the cruise mode is determined to be the fixed efficiency cruise mode, and the motor torque is adjusted along the target efficiency curve (i.e. Figure 6 ), so that the vehicle speed gradually decreases until the target efficiency torque is equal to the driving resistance. Figure 6 (a) in the figure shows that the driving resistance is above the target efficiency curve. Figure 6 (b) in the figure shows the case where the driving resistance is within the target efficiency curve. In both cases, the fixed-efficiency cruise mode can be used to ensure that the motor efficiency is always not less than the target efficiency value.

[0054] like Figure 7 As shown, if u=u h , and the target efficiency torque is greater than the current driving resistance, that is, the vehicle speed tends to exceed the operating range of the cruise mode, then the cruise mode is determined to be the fixed speed cruise mode, and the current vehicle speed u is maintained. h , adjust the motor torque in real time (i.e. reduce the motor torque) so that the motor torque is always equal to the driving resistance.

[0055] like Figure 8 As shown, if u=u l , and the target efficiency torque is less than the current driving resistance, that is, the vehicle speed tends to exceed the operating range of the cruise mode, then the cruise mode is determined to be the fixed speed cruise mode, and the current vehicle speed u is maintained. l , adjust the motor torque in real time (i.e. increase the motor torque) so that the motor torque is always equal to the driving resistance.

[0056] In the process of adjusting the motor torque in real time, the maximum output torque of the battery is calculated, and the required torque of the vehicle is compared with the maximum output torque of the battery, so that the required torque of the vehicle is always no greater than the maximum output torque of the battery.

[0057] To maintain the set target efficiency value at different vehicle speeds, the motor torque needs to be adjusted, and a PID controller model can be used. The control principle is as follows Fig. 9 as shown.

[0058] When the vehicle is running under certain conditions, when the speed reaches the cruising speed range, that is, u l ≤u≤u h , the vehicle enters the cruise mode. The target efficiency value of the vehicle is determined according to the driving requirements. The vehicle controller collects the motor speed n and the current output torque T(t) information. The actual motor efficiency corresponding to different motor torques at different speeds can be determined through the stored motor efficiency table, as shown in the following table:

[0059]

[0060] The efficiency deviation, Δη, can be calculated based on the set target efficiency value and the actual efficiency value. The efficiency deviation Δη is input into the PID control model, and the vehicle control torque T(t), i.e., the motor torque, is output. The vehicle PID control model is: Where T(t) is the control torque of the vehicle, Δη is the efficiency deviation, K P , K I , K D They are the control model proportion, integral coefficient and differential coefficient respectively, which are determined during system calibration.

[0061] After the vehicle output torque changes, the vehicle will accelerate or decelerate slightly according to the driving resistance. As mentioned in the previous constant-efficiency cruise mode, the motor speed changes, and the actual motor efficiency also changes, which is fed back to the control system. Through the adjustment of the system, the motor torque is constantly changing until it reaches a balance with the road resistance and the vehicle maintains a constant speed.

[0062] The present invention also provides a pure electric vehicle cruise control system based on fixed-efficiency cruise control, comprising:

[0063] The signal acquisition and processing module is used to obtain the target efficiency value and determine the target efficiency curve, collect the current motor speed in real time, and calculate the driving resistance curve, target efficiency torque, driving resistance, and current vehicle speed in real time;

[0064] A judgment module, used to determine the current cruise mode according to the current vehicle speed, target efficiency torque, and driving resistance;

[0065] A control module is used to adjust the motor torque according to the current cruise mode.

[0066] The present invention also provides a non-transitory computer-readable storage medium for storing a computer program or instruction. When the computer program or instruction is executed by a computer, the pure electric vehicle cruise control method based on fixed-efficiency cruise control is implemented.

[0067] The present invention also provides a computer program product, which includes computer instructions. When part or all of the computer instructions are run on a computer, the pure electric vehicle cruise control method based on fixed-efficiency cruise control is executed.

[0068] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The non-transitory computer-readable storage medium is a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a digital video disc (DVD)), or a semiconductor medium (e.g., a solid state disk (SSD)).

[0069] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A cruise control method for a pure electric vehicle based on fixed-efficiency cruise control, characterized in that: include: Obtain the motor efficiency torque map and preset target efficiency value, determine the target efficiency curve, and calculate the vehicle's driving resistance curve in real time; Calculate the target efficiency torque according to the current motor speed and the target efficiency curve, calculate the current driving resistance according to the current motor speed and the driving resistance curve, and adjust the current motor torque to the target efficiency torque; The cruise mode is determined based on the relationship between the target efficiency torque and the current driving resistance and the current vehicle speed u, and the motor torque is adjusted in real time according to the cruise mode. The current vehicle speed u is calculated based on the current motor speed. The cruise mode includes a constant-speed cruise mode and a constant-efficiency cruise mode. The constant-speed cruise mode maintains the current speed, and the constant-efficiency cruise mode keeps the motor efficiency always not less than the target efficiency value.

2. The cruise control method for a pure electric vehicle based on fixed-efficiency cruise control according to claim 1, characterized in that: The method for calculating the target efficiency torque includes: calculating the motor torque corresponding to the target efficiency curve according to the current motor speed; if there are two motor torques corresponding to the target efficiency curve, namely T1 and T2, the smaller value of T1 and T2 is used as the target efficiency torque; if there is only one motor torque corresponding to the target efficiency curve, it is directly used as the target efficiency torque.

3. The cruise control method for a pure electric vehicle based on fixed-efficiency cruise control according to claim 2 is characterized in that: The method for adjusting the motor torque in real time includes: l ≤u<u h , and the target efficiency torque is greater than the current driving resistance, the cruise mode is determined to be the fixed efficiency cruise mode, and the motor torque is adjusted along the target efficiency curve so that the vehicle speed gradually increases until the motor torque is equal to the driving resistance; Among them, u l is the minimum speed in the speed range corresponding to the target efficiency curve, u h is the maximum speed in the speed range corresponding to the target efficiency curve.

4. The cruise control method for a pure electric vehicle based on fixed-efficiency cruise control according to claim 2 is characterized in that: The method for adjusting the motor torque in real time includes: l <u≤u h , and the target efficiency torque is less than the current driving resistance, the cruise mode is determined to be the fixed-efficiency cruise mode, and the motor torque is adjusted along the target efficiency curve so that the vehicle speed gradually decreases until the target efficiency torque is equal to the driving resistance.

5. The cruise control method for a pure electric vehicle based on fixed-efficiency cruise control according to claim 2, characterized in that: The method of adjusting the motor torque in real time includes: if u=u h , and the target efficiency torque is greater than the current driving resistance, the cruise mode is determined to be the fixed speed cruise mode, and the current vehicle speed u is maintained. h , adjust the motor torque in real time so that the motor torque is always equal to the driving resistance.

6. The cruise control method for a pure electric vehicle based on fixed-efficiency cruise control according to claim 2, characterized in that: The method of adjusting the motor torque in real time includes: if u=u l , and the target efficiency torque is less than the current driving resistance, the cruise mode is determined to be the fixed speed cruise mode, and the current vehicle speed u is maintained. l , adjust the motor torque in real time so that the motor torque is always equal to the driving resistance.

7. The cruise control method for a pure electric vehicle based on fixed-efficiency cruise control according to any one of claims 1 to 6, characterized in that: In the process of real-time adjustment of the motor torque, the maximum output torque of the battery is calculated, and the required torque of the vehicle is compared with the maximum output torque of the battery, so that the required torque of the vehicle is always no greater than the maximum output torque of the battery.

8. A cruise control system for a pure electric vehicle based on fixed-efficiency cruise control, characterized in that: include: The signal acquisition and processing module is used to obtain the target efficiency value and determine the target efficiency curve, collect the current motor speed in real time, and calculate the driving resistance curve, target efficiency torque, driving resistance, and current vehicle speed in real time; A judgment module, used to determine the current cruise mode according to the current vehicle speed, target efficiency torque, and driving resistance; A control module is used to adjust the motor torque according to the current cruise mode.

9. A non-transitory computer-readable storage medium, characterized in that: Used to store computer programs or instructions. When the computer programs or instructions are executed by a computer, the pure electric vehicle cruise control method based on fixed-efficiency cruise as described in any one of claims 1-7 is implemented.

10. A computer program product, characterized in that The computer program product includes computer instructions; when part or all of the computer instructions are run on a computer, the pure electric vehicle cruise control method based on fixed-efficiency cruise control as described in any one of claims 1-7 is executed.

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