Control method and device of electric vehicle and electric vehicle

Abstract

The invention is suitable for the technical field of vehicle control, and provides a control method and device of an electric vehicle and the electric vehicle, and the method comprises the steps: obtaining an expected target speed value of the electric vehicle; performing feedforward control and proportional differential (PD) control on the expected target speed value to obtain an input voltage value of a motor in the electric vehicle; and according to the input voltage value, determining the speed value of the electric vehicle at the current moment so as to carry out speed closed-loop control at the next moment according to the speed value at the current moment. An integral part is removed on the basis of existing PID control to obtain proportional differential PD control, feed-forward control is introduced, the feed-forward control and the proportional differential PD control are combined to obtain an input voltage value of a motor, and speed closed-loop control over the electric vehicle is achieved by controlling the input voltage value, so that the electric vehicle is free of overshoot in the riding process, and the riding speed of the electric vehicle is improved. The speed overshoot phenomenon and the dragging feeling are effectively avoided, and the user experience feeling is improved.

Description

Technical Field

[0001] The present application belongs to the field of vehicle control technology, and in particular, relates to a control method and device for an electric vehicle and an electric vehicle. Background Art

[0002] In control engineering, proportional-integral-differential control (PID control) is a classic linear control method that optimizes the dynamic characteristics of the system by adjusting the three parameters of proportion, integration and differentiation to meet different control requirements. PID control adjusts the control quantity according to the system error. Usually, the PID controller consists of three basic parts: the proportional part (P), the integral part (I) and the differential part (D). Among them, the proportional part (P) is used to adjust the control quantity proportionally according to the size of the system error and respond quickly to the error change; the integral part (I) is used to integrate the system error, eliminate static errors, and improve control accuracy; the differential part (D) is used to adjust according to the rate of change of the error, predict the error change trend, and enhance the stability of the system.

[0003] At present, the speed closed-loop control scheme of two-wheeled electric vehicles usually adopts PID control, and the proportional coefficient, integral coefficient, and differential coefficient are adjusted according to different working conditions to achieve precise control of the speed. However, due to the relationship between the three parameters of proportional coefficient, integral coefficient, and differential coefficient, when adjusting these three parameters, any change in any parameter will cause a large overshoot of the system, and other parameters need to be adjusted repeatedly to achieve the appropriate setting. The adjustment process is cumbersome and the workload is large; at the same time, these three parameters are sensitive to factors such as the weight of the two-wheeled electric vehicle and the performance of the motor. The same parameters have different effects on different two-wheeled electric vehicles, and the overshoot is easy to be too large, resulting in a poor riding experience. Moreover, when the two-wheeled electric vehicle accelerates to the target speed of the speed closed-loop control, the torque will drop sharply, resulting in a sudden decrease in acceleration. This sudden deceleration will make the user feel that the vehicle seems to be dragged, affecting the riding comfort and experience. Summary of the invention

[0004] The embodiments of the present application provide a control method, device, equipment and electric vehicle for an electric vehicle, which can solve the problem that the existing speed closed-loop control method based on proportional-differential-integral PID control has a poor user experience due to excessive overshoot and the presence of a dragging feeling.

[0005] In a first aspect, an embodiment of the present application provides a control method for an electric vehicle, the method comprising:

[0006] Obtaining an expected target speed value of the electric vehicle;

[0007] Performing feedforward control and proportional differential (PD) control on the expected target speed value to obtain an input voltage value of a motor in the electric vehicle;

[0008] The current speed value of the electric vehicle is determined according to the input voltage value, so as to perform closed-loop speed control at the next moment according to the current speed value.

[0009] In a possible implementation of the first aspect, performing feedforward control and proportional differential (PD) control on the expected target speed value to obtain an input voltage value of a motor in the electric vehicle includes:

[0010] Obtaining the speed value of the electric vehicle at the last moment;

[0011] Performing feedforward control on the expected target speed value by a feedforward controller to obtain a feedforward control value;

[0012] Performing PD control on the expected target speed value and the speed value at the previous moment by a PD controller to obtain a PD control value;

[0013] The input voltage value of the motor is obtained according to the feedforward control value and the PD control value; wherein the motor is a permanent magnet synchronous motor.

[0014] In a possible implementation manner of the first aspect, performing PD control on the expected target speed value and the speed value at the previous moment by a PD controller to obtain a PD control value includes:

[0015] Calculate the expected target speed value and the speed value at the previous moment to obtain a current speed error value and a speed error value change rate;

[0016] The PD controller performs proportional differential adjustment on the current speed error value and the speed error value change rate to obtain the PD control value.

[0017] In a possible implementation manner of the first aspect, determining the current speed value of the electric vehicle according to the input voltage value includes:

[0018] The current speed value of the electric vehicle is determined according to the input voltage value and the control function of the motor; wherein the control function of the motor is:

[0019]

[0020] Among them, ω c is the speed value at the current moment; U q is the input voltage value; R is the equivalent resistance on the motor Q axis; i q is the current on the motor Q axis; It is the magnetic flux of the motor magnet.

[0021] In a possible implementation manner of the first aspect, performing feedforward control on the expected target speed value by a feedforward controller to obtain a feedforward control value includes:

[0022] The feedforward control value is obtained by multiplying the expected target speed value by a preset feedforward coefficient of the feedforward controller, wherein the preset feedforward coefficient is the inverse of the rated speed of the motor.

[0023] In a second aspect, an embodiment of the present application provides a control device for an electric vehicle, the device comprising:

[0024] An acquisition module, used for acquiring an expected target speed value of the electric vehicle;

[0025] A control module, used for performing feedforward control and proportional differential (PD) control on the expected target speed value to obtain an input voltage value of the motor in the electric vehicle;

[0026] The determination module is used to determine the current speed value of the electric vehicle according to the input voltage value, so as to perform speed closed-loop control at the next moment according to the current speed value.

[0027] In a possible implementation manner of the second aspect, the control module includes:

[0028] A speed acquisition unit, used to acquire the speed value of the electric vehicle at the last moment;

[0029] A feedforward control unit, used for performing feedforward control on the expected target speed value through a feedforward controller to obtain a feedforward control value;

[0030] A PD control unit, used for performing PD control on the expected target speed value and the speed value at the previous moment through a PD controller to obtain a PD control value;

[0031] A voltage determination unit is used to obtain the input voltage value of the motor according to the feedforward control value and the PD control value; wherein the motor is a permanent magnet synchronous motor.

[0032] In a possible implementation manner of the second aspect, the feedforward control unit is specifically configured to:

[0033] The feedforward control value is obtained by multiplying the expected target speed value by a preset feedforward coefficient of the feedforward controller, wherein the preset feedforward coefficient is the inverse of the rated speed of the motor.

[0034] In a third aspect, an embodiment of the present application provides a control device for an electric vehicle, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements any of the above-described control methods for the electric vehicle when executing the computer program.

[0035] In a fourth aspect, an embodiment of the present application provides an electric vehicle, the electric vehicle comprising a controller, the controller being used to execute a control method for the electric vehicle as described in any one of the above items.

[0036] In a sixth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the control method of the electric vehicle described in any one of the above items is implemented.

[0037] In a seventh aspect, an embodiment of the present application provides a computer program product, which, when executed on a terminal device, enables the terminal device to execute the electric vehicle control method described in any one of the above-mentioned first aspects.

[0038] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0039] The embodiment of the present application provides a control method for an electric vehicle, which obtains the expected target speed value of the electric vehicle; performs feedforward control and proportional differential PD control on the expected target speed value to obtain the input voltage value of the motor in the electric vehicle; determines the current speed value of the electric vehicle according to the input voltage value, so as to perform closed-loop speed control at the next moment according to the current speed value. Proportional differential PD control is obtained by removing the integral part on the basis of the existing PID control, and feedforward control is introduced, and the input voltage value of the motor is obtained by combining the feedforward control and the proportional differential PD control. The speed closed-loop control of the electric vehicle is achieved by controlling the input voltage value, so that the electric vehicle has no overshoot during riding, effectively avoiding speed overshoot and dragging, and improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 It is a structural schematic diagram of an existing PID-based speed closed-loop control solution provided by an embodiment of the present application;

[0042] Figure 2 It is a structural schematic diagram of a control method for an electric vehicle provided by an embodiment of the present application;

[0043] Figure 3 It is a flow chart of a control method of an electric vehicle provided by an embodiment of the present application;

[0044] Figure 4 is a structural schematic diagram of a control device for an electric vehicle provided in one embodiment of the present application;

[0045] Figure 5 is a structural schematic diagram of a control device for an electric vehicle provided by another embodiment of the present application;

[0046] Figure 6 It is a structural schematic diagram of an electric vehicle provided in one embodiment of the present application. DETAILED DESCRIPTION

[0047] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0048] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0049] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0050] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0051] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0052] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0053] Before describing the control method of the electric vehicle provided in this embodiment, the speed closed-loop control scheme based on PID is described first. Figure 1 As shown, Figure 1 1 is a schematic diagram of a structure of an existing PID-based speed closed-loop control solution provided by an embodiment of the present application. Figure 1 As shown in the figure, in the existing PID-based speed closed-loop control scheme, it is a common problem that the overshoot is too large, and the main reason is the integral part in the PID control algorithm. The existence of the integral part will cause the system to respond cumulatively to the error, resulting in overshoot. If the integral part in the PID control algorithm is directly removed, although the overshoot can be eliminated, it will also bring new problems, that is, the system may not be able to effectively eliminate the persistent error, resulting in a decrease in control accuracy, thus affecting the stability and performance of the system.

[0054] According to in-depth research and analysis, within a specific torque range, the controlled speed is linearly proportional to the torque. Specifically, the smaller the torque, the faster the controlled speed, which means that during the acceleration of electric vehicles, especially two-wheeled electric vehicles, the speed and torque change continuously rather than suddenly jumping. Due to this continuous change, users will not feel a sudden sense of drag during riding. This design can effectively solve the problem of drag and improve riding comfort and user experience.

[0055] Based on this, the embodiment of the present application removes the integral part based on the existing PID control and introduces feedforward control. Feedforward control mainly uses the mathematical relationship between the system input and output for prediction. Figure 2 As shown, Figure 2 It is a structural schematic diagram of a control method for an electric vehicle provided in one embodiment of the present application. Figure 2 In the process, the control actuator of the electric vehicle (such as the motor) measures the input signal of the system and uses a certain mathematical model to predict it to determine the required compensation signal (i.e., speed feedback), and then feeds this compensation signal back to the input signal of the system to offset the expected interference or error.

[0056] See also Figure 3 , Figure 3 1 is a flow chart of a control method for an electric vehicle provided in one embodiment of the present application. The method comprises:

[0057] S11, obtaining an expected target speed value of the electric vehicle;

[0058] S12, performing feedforward control and proportional differential PD control on the expected target speed value to obtain an input voltage value of the motor in the electric vehicle;

[0059] S13. Determine the current speed value of the electric vehicle according to the input voltage value, so as to perform closed-loop speed control at the next moment according to the current speed value.

[0060] It should be noted that, in this embodiment, the control method of the electric vehicle can be applied to two-wheeled electric vehicles or three-wheeled electric vehicles, and there is no specific limitation on this.

[0061] In this embodiment, the expected target speed value is the expected speed value set by the user or the electric vehicle system, that is, the target speed that the electric vehicle should reach. The input voltage value is the voltage value input to the motor in the electric vehicle, which determines the speed of the motor and the driving speed of the electric vehicle. Feedforward control is a prediction-based control method that adjusts the input voltage value of the motor in advance according to the change trend of the expected target speed value to eliminate some system response delays and nonlinear effects. Feedforward control can improve the accuracy and response speed of electric vehicle speed control. Proportional differential PD control is obtained by subtracting the integral part from the PID control, which is a control that combines the proportional part (P) and the differential part (D). Among them, the proportional part directly adjusts the control output (that is, the input voltage value of the motor) according to the size of the speed error; the differential part adjusts the control output according to the size of the speed error change rate to suppress the oscillation of the system and improve stability.

[0062] Specifically, the expected target speed value of the electric vehicle is first obtained; then, the expected target speed value is subjected to feedforward control and PD control, the input voltage value of the motor is predicted and adjusted to obtain the speed value at the current moment, and then the speed value at the current moment is fed back to the PD control, and the input voltage value of the motor is adjusted to achieve speed closed-loop control of the speed value at the next moment, thereby achieving precise speed control and ensuring that the electric vehicle travels at the desired speed.

[0063] It can be understood that the control method of an electric vehicle provided in the embodiment of the present application obtains the expected target speed value of the electric vehicle; performs feedforward control and proportional differential PD control on the expected target speed value to obtain the input voltage value of the motor in the electric vehicle; determines the current speed value of the electric vehicle according to the input voltage value, so as to perform closed-loop speed control at the next moment according to the current speed value. Proportional differential PD control is obtained by removing the integral part on the basis of the existing PID control, and feedforward control is introduced, and the input voltage value of the motor is obtained by combining the feedforward control and the proportional differential PD control. The speed closed-loop control of the electric vehicle is realized by controlling the input voltage value, so that the electric vehicle has no overshoot during riding, effectively avoiding speed overshoot and dragging, and improving the user experience.

[0064] In a possible implementation, feedforward control and proportional differential (PD) control are performed on the expected target speed value to obtain an input voltage value of a motor in an electric vehicle, including:

[0065] Get the speed value of the electric vehicle at the last moment;

[0066] Performing feedforward control on the expected target speed value through a feedforward controller to obtain a feedforward control value;

[0067] The PD controller performs PD control on the expected target speed value and the speed value at the previous moment to obtain a PD control value;

[0068] According to the feedforward control value and the PD control value, the input voltage value of the motor is obtained; wherein the motor is a permanent magnet synchronous motor.

[0069] It should be noted that the feedforward controller is a control device based on feedforward control, which is used to adjust the input voltage value of the motor in advance according to the change of the expected target speed value to eliminate some system response delays and nonlinear effects. The feedforward control value is the output value obtained after the feedforward control of the expected target speed value by the feedforward controller with the expected target speed value as the input. The feedforward control value is used to adjust the input voltage value of the motor.

[0070] The speed value at the previous moment is the actual driving speed value of the electric vehicle at the previous moment, which is used as speed feedback to compare with the expected target speed value and as an input parameter of the PD controller. The PD controller is a control device that combines proportional control and differential control, and is used to adjust the input voltage value of the motor according to the speed error and the speed error change rate to achieve precise speed control. The PD control value is the output value obtained by using the expected target speed value and the speed value at the previous moment as the input of the PD controller and performing PD regulation on the expected target speed value and the speed value at the previous moment through the PD controller. The PD control value is used to further adjust the input voltage value of the motor.

[0071] It should be noted that the motor of the electric vehicle in this embodiment is a permanent magnet synchronous motor. A permanent magnet synchronous motor is a synchronous motor that uses permanent magnets to generate a magnetic field. Among them, a surface-mounted permanent magnet synchronous motor is a permanent magnet synchronous motor commonly used in electric vehicles (especially two-wheeled electric vehicles and three-wheeled electric vehicles). Its permanent magnet is directly attached to the rotor of the motor, and has the characteristics of simple structure, high efficiency and low noise.

[0072] It should be understood that by adjusting the input voltage value of the motor by combining the feedforward controller and the PD controller, some system response delays and nonlinear effects can be eliminated, precise speed control can be achieved, and the system can have a faster response speed and higher stability.

[0073] In a possible implementation, a PD controller is used to perform PD control on an expected target speed value and a speed value at a previous moment to obtain a PD control value, including:

[0074] Calculate the expected target speed value and the speed value at the previous moment to obtain the current speed error value and the speed error value change rate;

[0075] The PD controller performs proportional differential adjustment on the current speed error value and the speed error value change rate to obtain the PD control value.

[0076] Specifically, Figure 2 In , the current speed error value is the difference between the expected target speed and the speed value at the previous moment, that is:

[0077] e=ω t -ω p ;

[0078] Among them, e is the current speed error value, ω t is the expected target speed value, ω p is the speed value at the previous moment.

[0079] The speed error value change rate is the value obtained by dividing the difference between the current speed error value and the speed error value at the previous moment by the time interval, that is:

[0080]

[0081] in, is the speed error value change rate, e ′ is the speed error value at the previous moment, Δt is the time interval.

[0082] The PD control value is the output value obtained by proportionally and differentially adjusting the current speed error value and the speed error value change rate through the PD controller, that is:

[0083]

[0084] Among them, U PD is the PD control value, K P is the proportionality coefficient, K S is the differential coefficient.

[0085] It should be noted that the proportional coefficient and differential coefficient need to be debugged and optimized according to the dynamic characteristics of the system.

[0086] It should be noted that the feedforward control value is:

[0087] U FF =ω t ×K F ;

[0088] Among them, U FF is the feedforward control value, K F is the feed-forward coefficient.

[0089] Then, the input voltage value U P =U PD +U FF .

[0090] In a possible implementation, determining the current speed value of the electric vehicle according to the input voltage value includes:

[0091] The current speed value of the electric vehicle is determined according to the input voltage value and the control function of the motor; wherein the control function of the motor is:

[0092]

[0093] Among them, ω c is the speed value at the current moment; U q is the input voltage value; R is the equivalent resistance on the motor Q axis; i q is the current on the motor Q axis; It is the magnetic flux of the motor magnet.

[0094] It should be noted that, in order to determine the current speed value of the electric vehicle, it is necessary to use a given control function of the motor, and the determination of the control function is described as follows.

[0095] When the speed of the electric vehicle is stable, the differential part in the PD controller is zero, and the control algorithm after the introduction of feedforward control can be shown as follows (1):

[0096] ((ω t -ω p )×K P +ω t ×K F )×G=ω c (1)

[0097] Among them, G is the control function of the motor, ω t is the expected target speed value, ω p is the speed value at the previous moment, K P is the proportionality coefficient, K F is the feedforward coefficient, ω c is the speed value at the current moment.

[0098] At this time, the speed of the electric vehicle is stable, so transforming formula (1) yields:

[0099]

[0100] Since the feedforward control does not change the poles of the system, it does not affect the stability of the system; while the feedforward control changes the zero point of the system, thereby speeding up the response speed of the system. The current speed error value is shown in formula (3):

[0101]

[0102] Therefore, according to the analysis of the above formulas (1)-(3), we can get: F When the current speed error value is reciprocal to the control function G of the motor, the current speed error value will be zero. Therefore, in order to achieve this goal, a deep understanding of the motor is essential, and the mathematical model of the permanent magnet synchronous motor is analyzed in the embodiment of the present application.

[0103] The mathematical model of the permanent magnet synchronous motor is the DQ axis model, which is a mathematical model on the DQ coordinate system obtained by transforming the mathematical model of the permanent magnet synchronous motor in the three-phase stationary coordinate system through Clarke transformation (CLARK) and Park transformation (PARK). The voltage on the Q axis of the DQ axis model is shown in formula (4):

[0104]

[0105] Among them, U q is the voltage on the motor Q axis, that is, the input voltage value; R is the equivalent resistance on the motor Q axis; i q is the current on the motor Q axis; is the magnetic flux on the motor Q axis; ω c is the current speed value of the motor; is the magnetic flux on the D axis of the motor.

[0106] In addition, the magnetic flux is as shown in formula (5):

[0107]

[0108] Among them, L d is the equivalent inductance on the motor D axis, L qis the equivalent inductance on the motor Q axis, i d is the current on the motor D axis, It is the magnetic flux of the motor magnet.

[0109] In the permanent magnet synchronous motor control d = 0 control strategy, L q =L d , when i d with i q When the amplitude of U does not change, q It can be simplified to formula (6), namely:

[0110]

[0111] Then, the current speed value of the motor is as shown in formula (7):

[0112]

[0113] That is, the control function of the motor is as shown in formula (7).

[0114] In addition, the electromagnetic torque is shown in formula (8):

[0115]

[0116] Among them, T e is the output torque of the motor.

[0117] It can be seen that the output torque T e Under the condition of no change, that is, the current i on the motor Q axis q unchanged, by adjusting the input voltage value U q In order to control the speed of the electric vehicle, the input voltage value U q The larger the current speed value ω c The larger the input voltage value U q Under the condition of no change, the output torque T of the motor e The larger the current i on the motor Q axis is, the q The larger it is, the lower the motor speed.

[0118] Under no-load conditions, the output torque is equal to 0, so the current i on the motor Q axis is q is equal to 0, so the speed of the motor, that is, the current speed value ω c With input voltage value U q In linear proportion.

[0119] Furthermore, the expected target speed value is feedforward controlled by a feedforward controller to obtain a feedforward control value, including:

[0120] The expected target speed value is multiplied by a preset feedforward coefficient of the feedforward controller to obtain a feedforward control value, wherein the preset feedforward coefficient is the inverse of the rated speed of the motor.

[0121] Following the above description, if Figure 2 As shown, in this embodiment, if the differential part is not considered, the input voltage value U at the motor input terminal is q for:

[0122] U q =(ω t -ω p )×K P +ω t ×K F (9)

[0123] Combining formula (9) with formula (7), we can get:

[0124]

[0125] If the current speed of the motor is equal to the expected target speed, then:

[0126] U q =ω t ×K F (11)

[0127] In the case of no-load, the current i on the motor Q axis q =0, then the current speed value is:

[0128]

[0129] If the current speed of the motor is the rated speed of the motor, then U q =100%, therefore, the feedforward coefficient K of the feedforward controller in this embodiment is F for:

[0130]

[0131] Among them, ω e is the rated speed of the motor.

[0132] Specifically, if the rated speed of the motor is 500 rpm, and assuming that the expected target speed value is 300 rpm, then the control output of the feedforward controller is 60%, and the current speed value of the motor is 300 rpm under no-load conditions.

[0133] It should be understood that when the motor load increases, the output torque of the motor increases, so that the current i on the motor Q axis qbecomes larger. According to formula (10), the motor speed will decrease linearly as the motor output torque increases. Then, during the acceleration process of the electric vehicle, the speed and output torque are continuous without step changes. Therefore, there is no dragging feeling caused by the existing PID-based speed closed-loop control solution.

[0134] The control method of the electric vehicle provided in this embodiment can achieve precise control under no-load. At the same time, under load, as the output torque increases, the speed decreases linearly, and the magnitude of the decrease can be controlled by adjusting the proportional coefficient. The larger the proportional coefficient, the smaller the magnitude of the decrease, and the smaller the proportional coefficient, the greater the magnitude of the decrease. In practical applications, a compromise is made between the riding experience and the speed error of the load, and the expected effect is obtained by adjusting the proportional coefficient.

[0135] Furthermore, the speed value at the current moment can be used as the feedback speed value to perform speed closed-loop control at the next moment, that is, the difference between the speed value at the current moment and the expected target speed value is calculated to obtain the speed error value at the next moment; then, the speed error value at the next moment and the rate of change of the speed error value at the next moment are proportionally differentially adjusted by the PD controller to obtain the PD control value at the next moment, and then, the next input voltage value of the motor is obtained according to the PD control value at the next moment and the feedforward control value, and the speed value of the electric vehicle is determined again according to the next input voltage value to perform the next speed closed-loop control.

[0136] It can be understood that, compared with the existing PID-based speed closed-loop control scheme, the control method of the electric vehicle provided in the embodiment of the present application has the following advantages:

[0137] (1) Electric vehicles accelerate and ride smoothly without overshoot, effectively avoiding speed overshoot.

[0138] (2) During the acceleration process of electric vehicles, the torque and speed change smoothly and continuously, completely eliminating step changes and thus solving the problem of drag.

[0139] (3) The system is easy to adjust parameters. Precise control can be achieved by simply configuring the rated speed and proportional coefficient of the motor. There is no need to repeatedly adjust parameters according to different vehicle models.

[0140] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0141] Corresponding to a control method of an electric vehicle in the above embodiment, Figure 4A schematic structural diagram of a control device for an electric vehicle provided in one embodiment of the present application is shown. For ease of explanation, only the portion related to the embodiment of the present application is shown.

[0142] Reference Figure 4 , the control device 3 of the electric vehicle of this embodiment includes:

[0143] An acquisition module 31 is used to acquire an expected target speed value of the electric vehicle;

[0144] A control module 32, for performing feedforward control and proportional differential PD control on the expected target speed value to obtain an input voltage value of the motor in the electric vehicle;

[0145] The determination module 33 is used to determine the current speed value of the electric vehicle according to the input voltage value, so as to perform speed closed-loop control at the next moment according to the current speed value.

[0146] It can be understood that the control device 3 of an electric vehicle provided in the embodiment of the present application obtains the expected target speed value of the electric vehicle through the acquisition module 31; then, the control module 32 performs feedforward control and proportional differential PD control on the expected target speed value to obtain the input voltage value of the motor in the electric vehicle; finally, the determination module 33 determines the current speed value of the electric vehicle according to the input voltage value, so as to perform closed-loop speed control at the next moment according to the current speed value. The electric vehicle speed control device 3 removes the integral part on the basis of the existing PID control to obtain the proportional differential PD control, and introduces feedforward control, combines the feedforward control and the proportional differential PD control to obtain the input voltage value of the motor, and realizes the closed-loop speed control of the electric vehicle by controlling the input voltage value, so that the electric vehicle has no overshoot during riding, effectively avoids speed overshoot and dragging, and improves the user experience.

[0147] Furthermore, the control module 32 includes:

[0148] A speed acquisition unit, used to acquire the speed value of the electric vehicle at the last moment;

[0149] A feedforward control unit, used for performing feedforward control on the expected target speed value through a feedforward controller to obtain a feedforward control value;

[0150] A PD control unit is used to perform PD control on an expected target speed value and a speed value at a previous moment through a PD controller to obtain a PD control value;

[0151] The voltage determination unit is used to obtain the input voltage value of the motor according to the feedforward control value and the PD control value; wherein the motor is a permanent magnet synchronous motor.

[0152] Furthermore, the feedforward control unit is specifically used for:

[0153] The expected target speed value is multiplied by a preset feedforward coefficient of the feedforward controller to obtain a feedforward control value, wherein the preset feedforward coefficient is the inverse of the rated speed of the motor.

[0154] Furthermore, the PD control unit is specifically used for:

[0155] Calculate the expected target speed value and the speed value at the previous moment to obtain the current speed error value and the speed error value change rate;

[0156] The PD controller performs proportional differential adjustment on the current speed error value and the speed error value change rate to obtain the PD control value.

[0157] Furthermore, the determination module 33 is specifically used for:

[0158] The current speed value of the electric vehicle is determined according to the input voltage value and the control function of the motor; wherein the control function of the motor is:

[0159]

[0160] Among them, ω c is the speed value at the current moment; U q is the input voltage value; R is the equivalent resistance on the motor Q axis; i q is the current on the motor Q axis; It is the magnetic flux of the motor magnet.

[0161] It should be noted that the information interaction, execution process, etc. between the modules in the control device 3 of the above-mentioned electric vehicle are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0162] Another embodiment of the present application also provides a control device for an electric vehicle, such as Figure 5 As shown, Figure 5 This is a schematic diagram of the structure of a control device for an electric vehicle provided by another embodiment of the present application. Figure 5 The control device 4 of the electric vehicle of this embodiment includes: a memory 41, a processor 42, and a computer program stored in the memory 41 and executable on the processor 42. When the processor 42 executes the computer program, the steps in any one of the above-mentioned electric vehicle control method embodiments are implemented.

[0163] The present application embodiment provides an electric vehicle, such as Figure 6 As shown, Figure 6 A schematic diagram of the structure of an electric vehicle provided in one embodiment of the present application. Figure 6The electric vehicle 5 of this embodiment includes: a controller 51, and the controller 51 is used to execute any of the above-mentioned control methods for the electric vehicle.

[0164] The embodiment of the present application further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments can be implemented.

[0165] An embodiment of the present application provides a computer program product. When the computer program product runs on a mobile terminal, the mobile terminal can implement the steps in the above-mentioned method embodiments when executing the computer program product.

[0166] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, which can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may at least include: any entity or device that can carry the computer program code to the camera / terminal device, a recording medium, a computer memory, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), an electric carrier signal, a telecommunication signal, and a software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electric carrier signals and telecommunication signals.

[0167] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0168] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0169] In the embodiments provided in the present application, it should be understood that the disclosed devices / network equipment and methods can be implemented in other ways. For example, the device / network equipment embodiments described above are only schematic. For example, the division of modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0170] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0171] The above embodiments 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, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These 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 control method for an electric vehicle, characterized in that: include: Obtaining an expected target speed value of the electric vehicle; Performing feedforward control and proportional differential (PD) control on the expected target speed value to obtain an input voltage value of a motor in the electric vehicle; The current speed value of the electric vehicle is determined according to the input voltage value, so as to perform closed-loop speed control at the next moment according to the current speed value.

2. The control method of the electric vehicle according to claim 1, characterized in that: The performing feedforward control and proportional differential (PD) control on the expected target speed value to obtain an input voltage value of the motor in the electric vehicle includes: Obtaining the speed value of the electric vehicle at the last moment; Performing feedforward control on the expected target speed value through a feedforward controller to obtain a feedforward control value; Performing PD control on the expected target speed value and the speed value at the previous moment by a PD controller to obtain a PD control value; The input voltage value of the motor is obtained according to the feedforward control value and the PD control value; wherein the motor is a permanent magnet synchronous motor.

3. The control method of the electric vehicle according to claim 2, characterized in that: The step of performing PD control on the expected target speed value and the speed value at the previous moment by using a PD controller to obtain a PD control value includes: Calculate the expected target speed value and the speed value at the previous moment to obtain a current speed error value and a speed error value change rate; The PD controller performs proportional differential adjustment on the current speed error value and the speed error value change rate to obtain the PD control value.

4. The control method of the electric vehicle according to claim 3, characterized in that: Determining the current speed value of the electric vehicle according to the input voltage value includes: The current speed value of the electric vehicle is determined according to the input voltage value and the control function of the motor; wherein the control function of the motor is: Among them, ω c is the speed value at the current moment; U q is the input voltage value; R is the equivalent resistance on the motor Q axis; i q is the current on the motor Q axis; It is the magnetic flux of the motor magnet.

5. The control method of the electric vehicle according to claim 4, characterized in that: The feedforward control of the expected target speed value by a feedforward controller to obtain a feedforward control value includes: The feedforward control value is obtained by multiplying the expected target speed value by a preset feedforward coefficient of the feedforward controller, wherein the preset feedforward coefficient is the inverse of the rated speed of the motor.

6. A control device for an electric vehicle, characterized in that: include: An acquisition module, used for acquiring an expected target speed value of the electric vehicle; A control module, used for performing feedforward control and proportional differential (PD) control on the expected target speed value to obtain an input voltage value of the motor in the electric vehicle; The determination module is used to determine the current speed value of the electric vehicle according to the input voltage value, so as to perform speed closed-loop control at the next moment according to the current speed value.

7. The control device for an electric vehicle according to claim 6, characterized in that: The control module comprises: A speed acquisition unit, used to acquire the speed value of the electric vehicle at the last moment; A feedforward control unit, configured to perform feedforward control on the expected target speed value through a feedforward controller to obtain a feedforward control value; A PD control unit, used for performing PD control on the expected target speed value and the speed value at the previous moment through a PD controller to obtain a PD control value; A voltage determination unit is used to obtain the input voltage value of the motor according to the feedforward control value and the PD control value; wherein the motor is a permanent magnet synchronous motor.

8. The control device for an electric vehicle according to claim 7, characterized in that: The feedforward control unit is specifically used for: The feedforward control value is obtained by multiplying the expected target speed value by a preset feedforward coefficient of the feedforward controller, wherein the preset feedforward coefficient is the inverse of the rated speed of the motor.

9. A control device for an electric vehicle, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the control method of the electric vehicle as claimed in any one of claims 1 to 5 when executing the computer program.

10. An electric vehicle, characterized in that: The electric vehicle comprises a controller, and the controller is used to execute the control method of the electric vehicle according to any one of claims 1 to 5.

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