A control method and device of an electric vehicle and the electric vehicle

Abstract

The application is suitable for the technical field of vehicle control, and provides a control method and device of an electric vehicle and the electric vehicle, the method comprising: 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; determining a current time speed value of the electric vehicle according to the input voltage value, so as to perform speed closed-loop control at the next time according to the current time speed value. The proportional differential (PD) control is obtained by removing the integral part on the basis of the existing PID control, and the feedforward control is introduced, 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 in the riding process, the speed overshoot phenomenon and the dragging feeling are effectively avoided, and the user experience is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of vehicle control, and particularly relates to a control method and device of an electric vehicle and the electric vehicle. BACKGROUND

[0002] In control engineering, proportional-integral-derivative control (PID control) is a classical linear control method, which realizes optimization of system dynamic characteristics by adjusting three parameters of proportion, integral and derivative, so as to meet different control requirements. PID control adjusts the control quantity according to the system error. Generally, a PID controller is composed of three basic parts of proportional part (P), integral part (I) and derivative part (D), wherein the proportional part (P) is used to adjust the control quantity in proportion to the size of the system error, to quickly respond to error changes; the integral part (I) is used to integrate the system error, to eliminate static error and improve control accuracy; and the derivative part (D) is used to adjust according to the error change rate, to predict error change trend and enhance system stability.

[0003] At present, the speed closed-loop control scheme of a two-wheeled electric vehicle usually adopts PID control, and the proportional coefficient, integral coefficient and derivative coefficient are adjusted according to different working conditions, to realize accurate control of the speed. However, the speed closed-loop control scheme based on PID, due to the mutual relationship among the three parameters of proportional coefficient, integral coefficient and derivative coefficient, when the three parameters are set, any change of one parameter will cause large overshoot of the system, and other parameters need to be repeatedly adjusted to achieve appropriate settings, so that the setting process is tedious and the workload is large; at the same time, the three parameters are sensitive to factors such as the weight of the two-wheeled electric vehicle and the performance of the motor, and the same parameters have different effects on different two-wheeled electric vehicles, so that the overshoot is prone to be too large, resulting in poor riding experience. Moreover, when the two-wheeled electric vehicle accelerates to the target speed of the speed closed-loop control, the torque will sharply decrease, resulting in sudden reduction of the acceleration, which makes the user feel that the vehicle is being dragged, and affects the comfort and experience of riding. SUMMARY

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

[0005] In a first aspect, the embodiments of the present application provide a control method of an electric vehicle, and the method comprises:

[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] determining a current time speed value of the electric vehicle according to the input voltage value, to perform speed closed-loop control at a next time according to the current time speed value.

[0009] In a possible implementation manner of the first aspect, the 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 comprises:

[0010] obtaining a last time speed value of the electric vehicle;

[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 last time speed value by a PD controller to obtain a PD control value;

[0013] obtaining 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.

[0014] In a possible implementation manner of the first aspect, the performing PD control on the expected target speed value and the last time speed value by the PD controller to obtain a PD control value comprises:

[0015] calculating the expected target speed value and the last time speed value to obtain a current speed error value and a speed error value change rate;

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

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

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

[0019]

[0020] wherein ω c is the current time speed value; U q is the input voltage value; R is an equivalent resistance on a Q-axis of the motor; i q is a current on the Q-axis of the motor; The magnetic chain of the motor magnetic steel.

[0021] In a possible implementation manner of the first aspect, the feeding forward control on the expected target speed value by the feeding forward controller includes:

[0022] multiplying the expected target speed value by a preset feeding forward coefficient of the feeding forward controller to obtain the feeding forward control value, wherein the preset feeding forward coefficient is an inverse of a rated rotating speed of the motor.

[0023] In the second aspect, the embodiments of the present application provide a control device of an electric vehicle, and the device includes:

[0024] an acquisition module configured to acquire an expected target speed value of the electric vehicle;

[0025] a control module configured to perform feeding forward 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;

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

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

[0028] a speed acquisition unit configured to acquire a last time speed value of the electric vehicle;

[0029] a feeding forward control unit configured to perform feeding forward control on the expected target speed value by a feeding forward controller to obtain a feeding forward control value;

[0030] a PD control unit configured to perform PD control on the expected target speed value and the last time speed value by a PD controller to obtain a PD control value;

[0031] a voltage determination unit configured to obtain the input voltage value of the motor according to the feeding forward 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 feeding forward control unit is specifically configured to:

[0033] multiply the expected target speed value by a preset feeding forward coefficient of the feeding forward controller to obtain the feeding forward control value, wherein the preset feeding forward coefficient is an inverse of a rated rotating speed of the motor.

[0034] In a third aspect, an embodiment of the present application provides a control device of an electric vehicle, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor implements the control method of the electric vehicle according to any one of the preceding aspects when executing the computer program.

[0035] In a fourth aspect, an embodiment of the present application provides an electric vehicle, comprising a controller configured to execute the control method of the electric vehicle according to any one of the preceding aspects.

[0036] In a sixth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program, when executed by a processor, implements the control method of the electric vehicle according to any one of the preceding aspects.

[0037] In a seventh aspect, an embodiment of the present application provides a computer program product, which, when executed on a terminal device, causes the terminal device to execute the control method of the electric vehicle according to any one of the first aspect.

[0038] Compared with the prior art, the embodiment of the present application has the following beneficial effects:

[0039] The control method of the electric vehicle provided by the embodiment of the present application comprises the following 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 determining a current time speed value of the electric vehicle according to the input voltage value, so as to perform speed closed-loop control at a next time according to the current time speed value. The proportional differential PD control is obtained by removing the integral part on the basis of the existing PID control, and the feedforward control is introduced, 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 there is no overshoot in the riding process of the electric vehicle, the speed overshoot phenomenon and the dragging feeling are effectively avoided, and the user experience is improved. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

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

[0042] Figure 2 is a structural schematic diagram of a control method of an electric vehicle according to an embodiment of the present application;

[0043] Figure 3 is a flowchart of a control method of an electric vehicle according to an embodiment of the present application;

[0044] Figure 4 is a structural schematic diagram of a control device of an electric vehicle according to an embodiment of the present application;

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

[0046] Figure 6 is a structural schematic diagram of an electric vehicle according to an embodiment of the present application. DETAILED DESCRIPTION

[0047] In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular sequences of acts, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

[0048] It is to be understood that the terminology "includes", "has", "holds", "contains" and / or "comprising", when used in this specification and in the following claims, indicates the presence of the described features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0049] It is also to be understood that the terminology "and / or" when used in this specification and in the following claims, refers to at least one of the items, or any combination of one or more of the items, and includes all possible combinations of one or more of the items.

[0050] As used in this specification and in the claims, the term "if" can be interpreted as meaning "when", or "once", or "in response to a determination", or "in response to detecting", as appropriate, depending on the context. Similarly, the phrase "if determined", or "if detected [the described condition or event]" can be interpreted as meaning "once determined", or "in response to a determination", or "once detected [the described condition or event]", or "in response to detecting [the described condition or event]", as appropriate, depending on the context.

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

[0052] In the present application, the reference to "one embodiment" or "some embodiments" means that the specific features, structures or characteristics described in connection with the embodiment are included in one or more embodiments of the present application. Therefore, the statements "in one embodiment", "in some embodiments", "in other some embodiments", "in further some embodiments" and the like appearing in the present description are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "include", "contain", "have" and their variants mean "including but not limited to", unless otherwise specifically emphasized.

[0053] Before the control method of the electric vehicle provided by the present embodiment is described, the PID-based speed closed-loop control scheme is described as follows. Figure 1 As shown in Figure 1 is a structural schematic diagram of the existing PID-based speed closed-loop control scheme according to an embodiment of the present application. As shown in Figure 1 In the existing PID-based speed closed-loop control scheme, the overshoot is usually too large, which is mainly caused by the integral part of the PID control algorithm. The existence of the integral part will cause the system to accumulate the response to the error, thereby causing the overshoot phenomenon. If the integral part of the PID control algorithm is directly removed, although the overshoot can be eliminated, it will also bring new problems, i.e. the system may not effectively eliminate the persistent error, resulting in a decrease in control accuracy, thereby affecting the stability and performance of the system.

[0054] According to in-depth research and analysis, it is found that within a certain torque range, the controlled speed is linearly proportional to the torque size. Specifically, the smaller the torque, the faster the controlled speed, which means that during the acceleration of the electric vehicle, especially the two-wheeled electric vehicle, the speed and torque are continuously changed, rather than suddenly jumping. Due to this continuous change, the user will not feel a sudden dragging feeling during riding, and this design can effectively solve the problem of dragging feeling and improve the riding comfort and user experience.

[0055] Based on this, the integral part is removed on the basis of the existing PID control, and a feedforward control is introduced. The feedforward control mainly uses the mathematical relationship between the system input and output for prediction. As shown in Figure 2 As shown in Figure 2 is a structural schematic diagram of the control method of the electric vehicle according to an embodiment of the present application.Figure 2 In the electric vehicle, a control actuator (such as a motor) measures the input signal of the system and uses a determined mathematical model to make a prediction to determine the required compensation signal (i.e. speed feedback) which is then fed back to the input signal of the system to cancel the expected disturbance or error.

[0056] Please refer to Figure 3 , Figure 3 is a flowchart of a control method of an electric vehicle provided in an 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 a motor in the electric vehicle;

[0059] S13, determining a current time speed value of the electric vehicle according to the input voltage value, so as to perform speed closed-loop control on a next time speed value according to the current time speed value.

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

[0061] In the embodiment, the expected target speed value is a desired speed value set by a user or a system of the electric vehicle, i.e. a target speed that the electric vehicle should reach. The input voltage value is a voltage value input to the motor in the electric vehicle, which determines the rotation speed of the motor and the driving speed of the electric vehicle. The feedforward control is a control method based on prediction, which adjusts the input voltage value of the motor in advance according to the variation trend of the expected target speed value to eliminate part of the system response time delay and nonlinear effect. The feedforward control can improve the accuracy and response speed of the speed control of the electric vehicle. The PD control is obtained by subtracting the integral part from the PID control, which is a combination of proportional part (P) and differential part (D). The proportional part directly adjusts the control output (i.e. 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 the stability.

[0062] Specifically, the expected target speed value of the electric vehicle is obtained first; then the feedforward control and PD control are performed on the expected target speed value, the input voltage value of the motor is predicted and adjusted to obtain the current time speed value, the current time speed value is fed back to the PD control, the input voltage value of the motor is adjusted to realize the speed closed-loop control on the next time speed value, so as to realize accurate speed control and ensure that the electric vehicle drives at the desired speed.

[0063] It can be understood that the control method of the electric vehicle provided by the embodiments of the present application comprises the following 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 determining a current time speed value of the electric vehicle according to the input voltage value, so as to perform speed closed-loop control at the next time according to the current time speed value. The proportional-differential (PD) control is obtained by removing the integral part from the existing PID control, and the feedforward control is introduced. 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, the speed overshoot phenomenon and the dragging feeling are effectively avoided, and the user experience is improved.

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

[0065] obtaining a last time speed value of the electric vehicle;

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

[0067] performing PD control on the expected target speed value and the last time speed value by a PD controller to obtain a PD control value;

[0068] obtaining 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.

[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 to eliminate part of the system response time delay and nonlinear effects according to the change of the expected target speed value. The feedforward control value is an output value obtained after the feedforward control of the expected target speed value by the feedforward controller, and the feedforward control value is used to adjust the input voltage value of the motor.

[0070] The last time speed value is the actual driving speed value of the electric vehicle at the previous time, which is used to compare with the expected target speed value as speed feedback and is used as an input parameter of the PD controller. The PD controller is a control device combining proportional control and differential control, which is used to adjust the input voltage value of the motor according to the speed error and the speed error change rate to realize accurate speed control. The PD control value is an output value obtained by performing PD adjustment on the expected target speed value and the last time speed value by 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 the embodiment is a permanent magnet synchronous motor. The permanent magnet synchronous motor is a synchronous motor using a permanent magnet to generate a magnetic field. Among them, the surface-mounted permanent magnet synchronous motor is a kind of permanent magnet synchronous motor commonly used in electric vehicles (especially two-wheeled electric vehicles and three-wheeled electric vehicles), and the permanent magnet is directly pasted on the rotor of the motor, which has the characteristics of simple structure, high efficiency and low noise.

[0072] It should be understood that the input voltage value of the motor is adjusted by combining the feedforward controller and the PD controller to eliminate part of the system response time delay and nonlinear effect, realize accurate speed control, and make the system have faster response speed and higher stability.

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

[0074] The expected target speed value and the speed value at the last moment are calculated to obtain a current speed error value and a speed error value change rate;

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

[0076] Specifically, as Figure 2 indicated in the description, the current speed error value is the difference between the expected target speed and the speed value at the last moment, that is:

[0077] e = ω t - ω p ;

[0078] Wherein, e is the current speed error value, ω t is the expected target speed value, and ω p is the speed value at the last moment.

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

[0080]

[0081] Wherein, is the speed error value change rate, e ′ is the speed error value at the last moment, and Δt is the time interval.

[0082] The PD control value is the output value obtained by the PD controller performing proportional and differential adjustment on the current speed error value and the speed error value change rate, that is:

[0083]

[0084] wherein, U PD is the PD control value, K P is the proportional coefficient, K S is the differential coefficient.

[0085] It should be noted that the proportional coefficient and the 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] wherein, U FF is the feedforward control value, K F is the feedforward coefficient.

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

[0090] In one possible implementation, the current time speed value of the electric vehicle is determined according to the input voltage value, comprising:

[0091] The current time 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] wherein, ω c is the current time speed value; U q is the input voltage value; R is the equivalent resistance on the Q-axis of the motor; i q is the current on the Q-axis of the motor; and is the flux of the motor magnetic steel.

[0094] It should be noted that in order to determine the current time speed value of the electric vehicle, the given control function of the motor needs to be used, 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 introducing the feedforward control can be shown in the following formula (1):

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

[0097] wherein G is a control function of the motor, ω t is an expected target speed value, ω p is a speed value at a previous time, K P is a proportional coefficient, K F is a feedforward coefficient, ω c is a speed value at a current time.

[0098] At this time, the speed of the electric vehicle is stable, and formula (1) can be transformed to obtain:

[0099]

[0100] Since the feedforward control does not change the pole of the system, that is, it does not affect the stability of the system; and the feedforward control changes the zero point of the system, thereby accelerating the response speed of the system. And the current speed error value is shown in formula (3):

[0101]

[0102] Therefore, according to the analysis of the above formulas (1)-(3), it can be obtained that the current feedforward coefficient K F is the reciprocal of the control function G of the motor, the current speed error value will be zero. Therefore, in order to achieve this goal, it is essential to have a deep understanding of the motor, and the mathematical model of the permanent magnet synchronous motor is analyzed in the embodiments of the present application.

[0103] The mathematical model of the permanent magnet synchronous motor is a D-Q axis model, which is a mathematical model in the D-Q coordinate system obtained after the mathematical model of the permanent magnet synchronous motor in the three-phase stationary coordinate system is subjected to CLARK transformation and PARK transformation. The voltage on the Q axis of the D-Q axis model is shown in formula (4):

[0104]

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

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

[0107]

[0108] wherein L d is the equivalent inductance on the D axis of the motor, L qLQ is the equivalent inductance on the motor Q-axis, i d is the current on the motor D-axis, is the flux of the motor magnetic steel.

[0109] Under the control strategy of i d = 0, L q = L d , when the amplitude of i d and i q does not change, U q can be simplified as formula (6), that is:

[0110]

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

[0112]

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

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

[0115]

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

[0117] It can be seen that, in the case of constant output torque T e , that is, the current i q on the motor Q-axis is constant, by adjusting the input voltage value U q , thereby controlling the speed of the electric vehicle, the greater the input voltage value U q , the greater the current speed value ω c . In the case of constant input voltage value U q , the greater the output torque T e of the motor, that is, the greater the current i q on the motor Q-axis, the smaller the speed of the motor.

[0118] In the case of no load, the output torque is equal to 0, then the current i q on the motor Q-axis is equal to 0, therefore, the speed of the motor, that is, the current speed value ω c is linearly proportional to the input voltage value U q .

[0119] Further, the expected target speed value is fed forward by the feedforward controller to obtain the 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 of 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 value of the motor is equal to the expected target speed value, 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 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 the current i on the motor Q axis increases. qThe motor speed will linearly decrease with the increase of the output torque of the motor according to formula (10). Therefore, the speed and the output torque of the electric vehicle are continuous during the acceleration process, and there is no step change. Thus, there is no dragging feeling caused by the existing PID-based speed closed-loop control scheme.

[0134] The control method of the electric vehicle provided in the embodiment can achieve accurate control under no load. Meanwhile, under load, the speed linearly decreases with the increase of the output torque, and the decreasing amplitude can be controlled by adjusting the proportional coefficient. The larger the proportional coefficient, the smaller the decreasing amplitude. The smaller the proportional coefficient, the larger the decreasing amplitude. In actual application, a compromise is made between the riding experience and the speed error under load, and the expected effect is obtained by adjusting the proportional coefficient.

[0135] Further, the speed value at the current moment can be taken as the feedback speed value for the speed closed-loop control at the next moment, that is, the speed value at the current moment is subtracted from the expected target speed value to obtain a speed error value at the next moment. Then, the proportional and differential adjustments are made on the speed error value at the next moment and the change rate of the speed error value at the next moment by the PD controller to obtain a PD control value at the next moment. 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. According to the next input voltage value, the speed value of the electric vehicle is determined again for 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 has the following advantages:

[0137] (1) The acceleration and riding of the electric vehicle are stable, and there is no overshoot, which effectively avoids the speed overshoot phenomenon.

[0138] (2) During the acceleration process of the electric vehicle, the torque and the speed achieve smooth and continuous change, and the step change is completely eliminated, thereby solving the problem of dragging feeling.

[0139] (3) The system parameter adjustment is simple, and accurate control can be achieved only by configuring the rated speed of the motor and the proportional coefficient, without repeatedly setting parameters according to different vehicle models.

[0140] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution. The execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment.

[0141] A control method of an electric vehicle corresponding to the above embodiment, Figure 4A structural schematic diagram of a control device of an electric vehicle is shown, and only parts related to the embodiments of the present application are shown for ease of illustration.

[0142] With reference to Figure 4 The control device 3 of the electric vehicle of the embodiments comprises:

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

[0144] A control module 32 is configured to perform feedforward control and proportional-derivative (PD) control on the expected target speed value to obtain an input voltage value of a motor in the electric vehicle.

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

[0146] It can be understood that the control device 3 of the electric vehicle provided by the embodiments of the present application acquires an expected target speed value of the electric vehicle through the acquisition module 31; then, the control module 32 performs feedforward control and proportional-derivative (PD) control on the expected target speed value to obtain an input voltage value of a motor in the electric vehicle; finally, the determination module 33 determines a current time speed value of the electric vehicle according to the input voltage value, so as to perform speed closed-loop control at a next time according to the current time speed value. The control device 3 of the electric vehicle speed controls the input voltage value of the motor by removing the integral part of the existing PID control to obtain proportional-derivative (PD) control, and introduces feedforward control, combines the feedforward control and the proportional-derivative (PD) control to obtain the input voltage value of the motor, and controls the input voltage value to realize the speed closed-loop control of the electric vehicle, so that the electric vehicle has no overshoot during riding, effectively avoids the speed overshoot phenomenon and the dragging feeling, and improves the user experience.

[0147] Further, the control module 32 comprises:

[0148] A speed acquisition unit is configured to acquire a last time speed value of the electric vehicle.

[0149] A feedforward control unit is configured to perform feedforward control on the expected target speed value through a feedforward controller to obtain a feedforward control value.

[0150] A PD control unit is configured to perform proportional-derivative (PD) control on the expected target speed value and the last time speed value through a PD controller to obtain a PD control value.

[0151] A voltage determination unit is configured 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] Further, the feedforward control unit is specifically configured to:

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

[0154] Further, the PD control unit is specifically configured to:

[0155] calculating the expected target speed value and the speed value at the last moment, to obtain a current speed error value and a speed error value change rate;

[0156] adjusting the current speed error value and the speed error value change rate by the PD controller to obtain a PD control value.

[0157] Further, the determining module 33 is specifically configured to:

[0158] determining the speed value at the current moment of the electric vehicle according to the input voltage value and a control function of the motor; wherein the control function of the motor is:

[0159]

[0160] wherein ω c is the speed value at the current moment; U q is the input voltage value; R is an equivalent resistance on a Q-axis of the motor; i q is a current on the Q-axis of the motor; and ψ is a magnetic flux of a magnetic steel of the motor.

[0161] It should be noted that the information interaction between the modules in the control device 3 of the electric vehicle, the execution process and the like are based on the same concept as the method embodiments of the present application, and the specific functions and the technical effects brought by the same can be referred to the method embodiments part, and will not be described herein.

[0162] Another embodiment of the present application further provides a control device of an electric vehicle. Figure 5 As shown in the figure, Figure 5 is a structural schematic diagram of a control device of an electric vehicle provided by another embodiment of the present application. Referring to Figure 5 , the control device 4 of the electric vehicle of this embodiment comprises a memory 41, a processor 42, and a computer program stored in the memory 41 and executable on the processor 42, and the processor 42 implements the steps in the control method embodiments of the electric vehicle of any one of the above embodiments when executing the computer program.

[0163] An embodiment of the present application provides an electric vehicle. Figure 6 As shown in the figure, Figure 6 is a structural schematic diagram of an electric vehicle provided by an embodiment of the present application. Referring to Figure 6The electric vehicle 5 of this embodiment includes a controller 51 configured to perform the control method of the electric vehicle of any one of the above embodiments.

[0164] The embodiments of the present application further provide a computer readable storage medium, which stores a computer program. The computer program is executed by a processor to implement the steps in the above method embodiments.

[0165] The embodiments of the present application provide a computer program product. When the computer program product is run on a mobile terminal, the mobile terminal is caused to implement the steps in the above method embodiments.

[0166] The integrated units, if realized in the form of software functional units and sold or used as independent products, can be stored in a computer readable storage medium. Based on such understanding, the present application can implement all or part of the processes in the above embodiments by a computer program to instruct related hardware to complete, and the computer program can be stored in a computer readable storage medium. The computer program is executed by a processor to implement the steps in the above method embodiments. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms. The computer readable medium at least includes any entity or device capable of carrying the computer program code to the photographing device / terminal equipment, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium. For example, U disk, mobile hard disk, magnetic disk or optical disk, etc. In some jurisdictions, according to legislation and patent practice, the computer readable medium cannot be an electrical carrier signal and a telecommunication signal.

[0167] In the above embodiments, the description of each embodiment has its own focus, and the parts not described or recorded in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0168] Those skilled in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0169] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / network device and method can be implemented in other manners. For example, the embodiments of the apparatus / network device described above are merely illustrative. For example, the division of the modules or units is merely logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between the units can be indirect couplings or communication connections through some interfaces, devices or units, and can be electrical, mechanical or in other forms.

[0170] The units described as separated components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e., can be located in one place or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments of the present application.

[0171] The above embodiments are merely used to describe the technical solutions of the present application, but not to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalent replacements; and these modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should 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 the motor in the electric vehicle, specifically comprising: obtaining a speed value of the electric vehicle at a previous 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 through a PD controller to obtain a PD control value; and obtaining the input voltage value of the motor based on the feedforward control value and the PD control value; wherein the motor is a permanent magnet synchronous motor; Determining a current speed value of the electric vehicle according to the input voltage value, so as to perform closed-loop speed control at a next moment according to the current speed value, specifically comprising: determining the current speed value of the electric vehicle according to the input voltage value and a control function of the motor; wherein the control function of the motor is: ;in, is the speed value at the current moment; is the input voltage value; is the equivalent resistance on the motor Q axis; is the current on the motor Q axis; is the magnetic flux of the motor magnet.

2. The control method of an electric vehicle according to claim 1, wherein: The 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: Calculating 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.

3. The control method of the electric vehicle according to claim 2, 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.

4. 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, configured to perform 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; a determination module, configured to determine a current speed value of the electric vehicle according to the input voltage value, so as to perform closed-loop speed control at a next moment according to the current speed value; Wherein, the control module includes: A speed acquisition unit, configured to acquire the speed value of the electric vehicle at a previous 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, configured to perform 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, configured 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; The determining module is specifically configured to: 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: ； in, is the speed value at the current moment; is the input voltage value; is the equivalent resistance on the motor Q axis; is the current on the motor Q axis; is the magnetic flux of the motor magnet.

5. The control device for an electric vehicle according to claim 4, wherein: 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.

6. A control device for an electric vehicle, characterized in that: The method 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 according to any one of claims 1 to 3 when executing the computer program.

7. An electric vehicle, characterized in that: The electric vehicle includes a controller configured to execute the electric vehicle control method according to any one of claims 1 to 3.

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