Permanent magnet synchronous motor sliding mode control method based on novel speed change index reaching law

Abstract

The invention discloses a permanent magnet synchronous motor sliding mode control method based on a novel speed change index reaching law, and relates to the technical field of motor control, and the method comprises the steps: S1, building a state space mathematical model of a permanent magnet synchronous motor based on a d-q synchronous rotating coordinate system; s2, establishing a sliding mode control law of the permanent magnet synchronous motor according to the state space mathematical model of the permanent magnet synchronous motor; and S3, using the sliding mode control law of the permanent magnet synchronous motor to obtain a sliding mode control result of the permanent magnet synchronous motor based on a Lyapunov function. The novel variable-speed exponential reaching law sliding mode control provided by the invention reduces the buffeting of the system, shortens the time required by the system state to reach the surface of the sliding mode, and has fast transient response and strong robust anti-interference capability.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a sliding mode control method of a permanent magnet synchronous motor based on a novel variable speed exponential reaching law. Background Art

[0002] Permanent magnet synchronous motor (PMSM) is widely used in industrial and consumer applications such as robot arms and printers due to its low manufacturing cost and good open-loop performance. However, PMSM is a complex control object with multiple variables, strong coupling, nonlinearity, and variable parameters. Sliding mode controller, as a nonlinear control method widely used in PMSM, has received extensive attention. Its core idea is to drive the system dynamically to a low-order sliding mode surface through discontinuous switching control, but the high switching gain in sliding mode control can cause significant jitter. In addition, most of the sliding mode control methods currently used cannot balance jitter and robustness well, and there are complex design problems. Summary of the invention

[0003] The purpose of the present invention is to propose a sliding mode control method for a permanent magnet synchronous motor based on a new variable speed exponential reaching law, by which an enhanced reaching law is combined with a sliding surface that adapts to the sliding surface and the changes in the system state to reduce chattering and minimize the arrival time.

[0004] To achieve the above object, the present invention provides a sliding mode control method for a permanent magnet synchronous motor based on a novel speed exponential reaching law, comprising the following steps: S1. Establish a state space mathematical model of the permanent magnet synchronous motor based on the dq synchronous rotating coordinate system; S2. Establishing a sliding mode control law of the permanent magnet synchronous motor according to the state space mathematical model of the permanent magnet synchronous motor; S3. Obtaining a sliding mode control result of the permanent magnet synchronous motor based on the Lyapunov function using the sliding mode control law of the permanent magnet synchronous motor.

[0005] Optionally, a state space mathematical model of a permanent magnet synchronous motor is established based on a dq synchronous rotating coordinate system, including: S1-1. Based on the dq synchronous rotating coordinate system, the d-axis voltage, p-axis voltage and torque equations of the permanent magnet synchronous motor stator during synchronous rotation are established; S1-2. Obtain a state space mathematical model of the permanent magnet synchronous motor according to the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation.

[0006] Optionally, the calculation formula of the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation is as follows:

[0007] in, i d is the stator current along the d-axis, t For time, L d is the inductance on the d-axis, u d is the stator voltage on the d-axis, R s is the stator resistance, ω e is the electrical angular velocity, L q is the inductance on the q-axis, i q is the stator current along the q axis, u q is the stator voltage on the q axis, Ψ f is the permanent magnet flux, ω m is the mechanical angular velocity, J is the moment of inertia of the load, T e is the electromagnetic torque, B a is the viscosity coefficient of the load, T L is the load torque, p is the number of pole pairs of the motor.

[0008] Optionally, obtaining the state space mathematical model of the permanent magnet synchronous motor according to the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation includes: S1-2-1, performing rotor magnetic field oriented control according to the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation to obtain rotor magnetic field oriented control information; S1-2-2, determine the state variables of the permanent magnet synchronous motor; S1-2-3. Obtain the state space equation of the permanent magnet synchronous motor as the state space mathematical model of the permanent magnet synchronous motor according to the state variables of the permanent magnet synchronous motor and the rotor magnetic field oriented control information.

[0009] Optionally, the calculation formula of the state space equation of the permanent magnet synchronous motor is as follows:

[0010] in, , They are x 1. xThe first derivative of 2, , , x 1 is the speed error of the permanent magnet synchronous motor, x 2 for x The first derivative of 1, ω ref is the reference speed of the permanent magnet synchronous motor, ω m is the mechanical angular velocity, is the first-order derivative of the mechanical angular velocity, D is the coefficient of the control input, u is the permanent magnet synchronous motor control input and is the sliding mode controller output.

[0011] Optionally, establishing a sliding mode control law of the permanent magnet synchronous motor according to the state space mathematical model of the permanent magnet synchronous motor includes: S2-1, obtain a new speed exponential reaching law and sliding film surface function of the speed loop sliding mode controller of the permanent magnet synchronous motor; S2-2. According to the state space mathematical model of the permanent magnet synchronous motor, the sliding mode control law of the permanent magnet synchronous motor is obtained by utilizing the novel speed exponential approach law and sliding film surface function of the speed loop sliding mode controller of the permanent magnet synchronous motor.

[0012] Optionally, the calculation formula of the novel variable exponential reaching law of the permanent magnet synchronous motor speed loop sliding mode controller is as follows:

[0013] in, is the first-order derivative of the sliding surface, ε is the coefficient of the constant velocity approach term, F ( x,t ) is the additional function of the variable speed approach term, x is the state variable of the permanent magnet synchronous motor system, t is time, tanh(▪) is the additional function of the variable exponential approach term, s is the sliding surface function, k is the exponential approach coefficient, G ( s ) is the additional function of the variable exponential approach term, α is a constant.

[0014] Optionally, the calculation formula of the sliding mode surface function of the permanent magnet synchronous motor speed loop sliding mode controller is as follows:

[0015] in, s is the sliding surface function, C is a constant greater than zero, x1 is the speed error of the permanent magnet synchronous motor, x 2 for x The first derivative of 1.

[0016] Optionally, the calculation formula of the sliding mode control law of the permanent magnet synchronous motor is as follows:

[0017] in, i q_NewEAL is the output of the sliding mode controller, D is the coefficient of the control input, t For time, C is a constant greater than zero, x 1 is the speed error of the permanent magnet synchronous motor, ε is the coefficient of the constant velocity approach term, F ( x,t ) is the additional function of the variable speed approach term, x is the state variable of the permanent magnet synchronous motor system, tanh(▪) is the additional function of the variable exponential approach term, s is the sliding surface function, k is the exponential approach coefficient, G ( s ) is an additional function of the variable exponential approach term.

[0018] Optionally, obtaining a sliding mode control result of the permanent magnet synchronous motor based on the Lyapunov function by using the sliding mode control law of the permanent magnet synchronous motor includes: S3-1, constructing a Lyapunov function according to the sliding surface function of the permanent magnet synchronous motor speed loop sliding mode controller; S3-2. Based on the Lyapunov function, a derivative value of the Lyapunov function is obtained according to the state space mathematical model of the permanent magnet synchronous motor as a sliding mode control result of the permanent magnet synchronous motor.

[0019] Compared with the closest prior art, the present invention has the following beneficial effects: The new sliding mode reaching law of the present invention combines the enhanced reaching law with the sliding mode surface that adapts to the sliding mode surface and the changes in the system state, thereby reducing the chattering and minimizing the arrival time; the present invention replaces the sign function that causes the chattering with the hyperbolic tangent function in the reaching law, and adds additional functions of the variable speed reaching term and the variable exponential reaching term, thereby reducing the chattering and having strong dynamic performance and robust anti-interference ability for uncertain speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a flow chart of a sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to an embodiment of the present invention; Figure 2 A schematic diagram of the implementation principle of the sliding mode control method for a permanent magnet synchronous motor proposed in an embodiment of the present invention; Figure 3 A speed comparison diagram of a traditional proportional-integral control method with different reference speeds proposed in an embodiment of the present invention; Figure 4 A speed comparison diagram of a sliding mode control method of a novel speed-changing exponential reaching law for different reference speeds proposed in an embodiment of the present invention; Figure 5 A speed comparison diagram of the sliding mode control method of the traditional exponential reaching law with different reference speeds proposed in an embodiment of the present invention; Figure 6 A speed comparison diagram of the traditional proportional-integral control method proposed in an embodiment of the present invention when the speed suddenly changes; Figure 7 A speed comparison diagram of the sliding mode control method of the traditional exponential reaching law proposed in an embodiment of the present invention and the traditional sliding surface when the speed suddenly changes; Figure 8 This is a speed comparison diagram of the sliding mode control method of the novel speed-changing exponential reaching law proposed in an embodiment of the present invention and the traditional sliding mode surface when the speed changes suddenly. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The terms used in the embodiments of the present invention are only used to explain the specific embodiments of the present invention and are not intended to limit the present invention.

[0024] Example 1: Figure 1As shown, an embodiment of the present invention provides a sliding mode control method for a permanent magnet synchronous motor based on a novel variable speed exponential reaching law, comprising the following steps: S1. Establish a state space mathematical model of the permanent magnet synchronous motor based on the dq synchronous rotating coordinate system; S2. Establishing a sliding mode control law of the permanent magnet synchronous motor according to the state space mathematical model of the permanent magnet synchronous motor; S3. Obtaining a sliding mode control result of the permanent magnet synchronous motor based on the Lyapunov function using the sliding mode control law of the permanent magnet synchronous motor.

[0025] S1 specifically includes: S1-1. Based on the dq synchronous rotating coordinate system, the d-axis voltage, p-axis voltage and torque equations of the permanent magnet synchronous motor stator during synchronous rotation are established; S1-2. Obtain a state space mathematical model of the permanent magnet synchronous motor according to the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation.

[0026] The calculation formulas of the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation are as follows:

[0027] in, i d is the stator current along the d-axis, t For time, L d is the inductance on the d-axis, u d is the stator voltage on the d-axis, R s is the stator resistance, ω e is the electrical angular velocity, L q is the inductance on the q-axis, i q is the stator current along the q axis, u q is the stator voltage on the q axis, Ψ f is the permanent magnet flux, ω m is the mechanical angular velocity, J is the moment of inertia of the load, T e is the electromagnetic torque, B a is the viscosity coefficient of the load, T L is the load torque, p is the number of pole pairs of the motor.

[0028] S1-2 specifically includes: S1-2-1, performing rotor magnetic field oriented control according to the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation to obtain rotor magnetic field oriented control information; S1-2-2, determine the state variables of the permanent magnet synchronous motor; S1-2-3. Obtain the state space equation of the permanent magnet synchronous motor as the state space mathematical model of the permanent magnet synchronous motor according to the state variables of the permanent magnet synchronous motor and the rotor magnetic field oriented control information.

[0029] The calculation formula of the state space equation of the permanent magnet synchronous motor is as follows:

[0030] in, , They are x 1. x The first derivative of 2, , , x 1 is the speed error of the permanent magnet synchronous motor, x 2 for x The first derivative of 1, ω ref is the reference speed of the permanent magnet synchronous motor, ω m is the mechanical angular velocity, is the first-order derivative of the mechanical angular velocity, D is the coefficient of the control input, u is the permanent magnet synchronous motor control input and is the sliding mode controller output.

[0031] S2 specifically includes: S2-1, obtain a new speed exponential reaching law and sliding film surface function of the speed loop sliding mode controller of the permanent magnet synchronous motor; S2-2. According to the state space mathematical model of the permanent magnet synchronous motor, the sliding mode control law of the permanent magnet synchronous motor is obtained by utilizing the novel speed exponential approach law and sliding film surface function of the speed loop sliding mode controller of the permanent magnet synchronous motor.

[0032] The calculation formula of the novel variable exponential reaching law of the permanent magnet synchronous motor speed loop sliding mode controller is as follows:

[0033] in, is the first-order derivative of the sliding surface, ε is the coefficient of the constant velocity approach term, F ( x,t ) is the additional function of the variable speed approach term,x is the state variable of the permanent magnet synchronous motor system, t is time, tanh(▪) is the additional function of the variable exponential approach term, s is the sliding surface function, k is the exponential approach coefficient, G ( s ) is the additional function of the variable exponential approach term, α is a constant.

[0034] The calculation formula of the sliding mode surface function of the permanent magnet synchronous motor speed loop sliding mode controller is as follows:

[0035] in, s is the sliding surface function, C is a constant greater than zero, x 1 is the speed error of the permanent magnet synchronous motor, x 2 for x The first derivative of 1.

[0036] The calculation formula of the sliding mode control law of the permanent magnet synchronous motor is as follows:

[0037] in, i q_NewEAL is the output of the sliding mode controller, D is the coefficient of the control input, t For time, C is a constant greater than zero, x 1 is the speed error of the permanent magnet synchronous motor, ε is the coefficient of the constant velocity approach term, F ( x,t ) is the additional function of the variable speed approach term, x is the state variable of the permanent magnet synchronous motor system, tanh(▪) is the additional function of the variable exponential approach term, s is the sliding surface function, k is the exponential approach coefficient, G ( s ) is an additional function of the variable exponential approach term.

[0038] S3 specifically includes: S3-1, constructing a Lyapunov function according to the sliding surface function of the permanent magnet synchronous motor speed loop sliding mode controller; S3-2. Based on the Lyapunov function, a derivative value of the Lyapunov function is obtained according to the state space mathematical model of the permanent magnet synchronous motor as a sliding mode control result of the permanent magnet synchronous motor.

[0039] Embodiment 2: The embodiment of the present invention provides a sliding mode control method for a permanent magnet synchronous motor based on a new speed exponential reaching law, including: establishing a mathematical model of the permanent magnet synchronous motor in a dq synchronous rotating coordinate system; designing a speed loop sliding mode controller of the permanent magnet synchronous motor, including designing a new speed exponential reaching law and a sliding mode surface function, and deriving a sliding mode control law based on this reaching law; performing a stability analysis on the sliding mode controller to prove that the sliding mode controller is stable under the sliding mode control with the new speed exponential reaching law.

[0040] A mathematical model of a permanent magnet synchronous motor in a dq synchronous rotating coordinate system is established. First, the dp-axis voltage and torque equations of the permanent magnet synchronous motor stator during synchronous rotation are established. The dp-axis voltage and torque equations are as follows:

[0041] in, i d is the stator current along the d-axis, t For time, L d is the inductance on the d-axis, u d is the stator voltage on the d-axis, R s is the stator resistance, ω e is the electrical angular velocity, L q is the inductance on the q-axis, i q is the stator current along the q axis, u q is the stator voltage on the q axis, Ψ f is the permanent magnet flux, ω m is the mechanical angular velocity, J is the moment of inertia of the load, T e is the electromagnetic torque, B a is the viscosity coefficient of the load, T L is the load torque, p is the number of pole pairs of the motor.

[0042] Pick i d =0, the rotor magnetic field oriented control information is obtained, that is, equations (2) and (3) become: (5) (6) Then, the state space equation of the permanent magnet synchronous motor is set according to the above equation.

[0043] Specifically, first determine the state variables of the permanent magnet synchronous motor system: (7) (8) in, x 1 is the speed error of the permanent magnet synchronous motor, x 2 for x The first derivative of 1, ω ref is the reference speed of the permanent magnet synchronous motor, usually a constant. for x The first derivative of 1, is the first-order derivative of the mechanical angular velocity. According to the equation, from equations (5), (6), (7) and (8), we can know that: (9) (10) in, for x The first derivative of 2, is the second-order derivative of the mechanical angular velocity; set up u = i q , , then the state space equation of the permanent magnet synchronous motor is obtained, that is, equation (9) and equation (10) become: (11) in, D is the coefficient of the control input, u is the permanent magnet synchronous motor control input and is the sliding mode controller output.

[0044] Design a sliding mode controller for the speed loop of a permanent magnet synchronous motor, including designing a new speed index reaching law and a sliding surface function, and deriving a sliding mode control law based on this reaching law, including: designing a new speed index reaching law; designing a suitable sliding surface function; combining the mathematical model of the permanent magnet synchronous motor in the dq synchronous rotating coordinate system, deriving a sliding mode control law based on the new speed index reaching law, specifically: The new speed exponential reaching law is: (12) in, is the first-order derivative of the sliding surface, ε is the coefficient of the constant velocity approach term, F ( x,t ) is the additional function of the variable speed approach term,x is the state variable of the permanent magnet synchronous motor system, tanh(▪) is the additional function of the variable exponential approach term, is the sliding surface function, k is the exponential approach coefficient, G ( s ) is the additional function of the variable exponential approach term, α is a constant (between 0 and 1); The sliding surface function is: (13) in, C is a constant greater than zero; Combined with the mathematical model of the permanent magnet synchronous motor in the dq synchronous rotating coordinate system, the output of the sliding mode controller can be obtained, that is, the sliding mode control law of the permanent magnet synchronous motor can be obtained: (14) in, i q_NewEAL is the output of the sliding mode controller.

[0045] The stability analysis of the sliding mode controller is carried out to prove the stability of the sliding mode controller under the new variable speed exponential reaching law sliding mode control, including: setting the controlled system, selecting the target sliding mode surface function, combining the new variable speed exponential reaching law to derive the sliding mode control law; constructing the Lyapunov function, and proving the stability of the system according to the Lyapunov stability theorem. Specifically: The controlled system is: (15) in, is the second-order derivative of the position signal, f ( x,t ) is the function of the position instruction, h is a constant (greater than 0), u ( t ) represents the control input, d ( t ) indicates external interference; The target sliding surface function is: (16) in, c is a constant, which must satisfy the Hurwitz condition, c >0, e ( t ) is the tracking error, is the first-order derivative of the tracking error; The tracking error and its derivative are: (17) in, x 1= x , x d For the ideal position signal, is the first-order derivative of the ideal position signal; By taking the derivative of formula (17), we can get: (18) in, is the first-order derivative of the target sliding surface, is the second-order derivative of the tracking error, is the first-order derivative of the position signal, is the second-order derivative of the ideal position signal, is the second-order derivative of the signal position; Combining the new variable speed exponential reaching law, the sliding mode control law is obtained: (19) in, u ( t ) is the control input; Then, the Lyapunov function is constructed and the system is proved to be stable according to the Lyapunov stability theorem.

[0046] Among them, the Lyapunov function constructed according to the synovial surface function V as follows: (20) According to the Lyapunov function and the mathematical model of the permanent magnet synchronous motor in the dq synchronous rotating coordinate system, that is, combining equation (9) and equation (20), it can be derived that: (twenty one) in, is the derivative value of the Lyapunov function; According to Lyapunov's stability theorem, the designed sliding mode controller is gradually stable.

[0047] like Figure 2 The working principle of the PMSM controller is shown in the figure. The outer loop is the speed loop, which uses the detected speed ω As feedback; the inner loop is the current loop, which uses current sampling to obtain the stator three-phase current i a , i b and i c , and then through Clark transformation and Park transformation, we can get the stator current in the dq synchronous reference frame i d ,i q As feedback. Given speed and measured speed ω m After the difference is made, the given value of the q-axis stator current is obtained through the sliding mode controller. , and the d-axis current given value The given value and the measured value of the two current components are subtracted and then the stator voltage in the dq synchronous reference system is obtained through the PI controller. u d and u q , both are obtained through PARK inverse transformation α - β Stator voltage in coordinate system u α and u β , which is input into SVPWM to obtain the three-phase duty cycle signal, and controls the on and off of the inverter switch tube, thereby realizing the control of PMSM.

[0048] like Figure 3-Figure 8 As shown, the effects of the motor control method of the present invention and the prior art are compared, wherein Ref is a given reference speed, PI is a traditional proportional integral control method, and TEAL is a sliding mode control method using a traditional exponential reaching law, and its traditional exponential reaching law is: (twenty two) in, εsgn ( s ) is the isokinetic approach term, ks represents the exponential approach term; NewEAL is a sliding mode control method that adopts the new variable speed exponential reaching law proposed by the present invention. TMSM is a traditional sliding surface, and its sliding surface function is shown in Formula (13). It can be seen that the speed characteristics and system robustness of the present invention are the best.

[0049] The embodiment of the present invention also provides a computer-readable storage medium, on which a computer program is stored, and the computer program is executed to run a sliding mode control method for a permanent magnet synchronous motor based on a novel variable speed exponential reaching law. The computer program can run computer instructions, and the computer instructions include computer program code, and the computer program code can be in source code form, object code form, executable file, or some intermediate form, etc.

[0050] Computer-readable storage media may include: any entity or device that can carry computer program code, recording media, USB flash drives, mobile hard disks, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0051] It should be noted that the content contained in computer-readable storage media can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, the content contained in computer-readable storage media does not include electrical carrier signals and telecommunication signals.

[0052] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0053] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0054] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0055] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A sliding mode control method for a permanent magnet synchronous motor based on a novel speed exponential reaching law, characterized in that: The specific steps include: S1. Establish a state space mathematical model of the permanent magnet synchronous motor based on the dq synchronous rotating coordinate system; S2. Establishing a sliding mode control law of the permanent magnet synchronous motor according to the state space mathematical model of the permanent magnet synchronous motor; S3. Obtaining a sliding mode control result of the permanent magnet synchronous motor based on the Lyapunov function using the sliding mode control law of the permanent magnet synchronous motor.

2. The sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to claim 1 is characterized in that: The state space mathematical model of the permanent magnet synchronous motor based on the dq synchronous rotating coordinate system includes: S1-1. Based on the dq synchronous rotating coordinate system, the d-axis voltage, p-axis voltage and torque equations of the permanent magnet synchronous motor stator during synchronous rotation are established; S1-2. Obtain a state space mathematical model of the permanent magnet synchronous motor according to the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation.

3. The sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to claim 2 is characterized in that: The calculation formulas of the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation are as follows: in, i d is the stator current along the d-axis, t For time, L d is the inductance on the d-axis, u d is the stator voltage on the d-axis, R s is the stator resistance, ω e is the electrical angular velocity, L q is the inductance on the q-axis, i q is the stator current along the q axis, u q is the stator voltage on the q axis, Ψ f is the permanent magnet flux, ω m is the mechanical angular velocity, J is the moment of inertia of the load, T e is the electromagnetic torque, B a is the viscosity coefficient of the load, T L is the load torque, p is the number of pole pairs of the motor.

4. The sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to claim 2 is characterized in that: The state space mathematical model of the permanent magnet synchronous motor is obtained according to the d-axis voltage, the p-axis voltage and the torque equation of the permanent magnet synchronous motor stator during synchronous rotation, including: S1-2-1, performing rotor magnetic field oriented control according to the d-axis voltage, p-axis voltage and torque equation of the permanent magnet synchronous motor stator during synchronous rotation to obtain rotor magnetic field oriented control information; S1-2-2, determine the state variables of the permanent magnet synchronous motor; S1-2-3. Obtain the state space equation of the permanent magnet synchronous motor according to the state variables of the permanent magnet synchronous motor and the rotor magnetic field oriented control information as the state space mathematical model of the permanent magnet synchronous motor.

5. The sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to claim 4 is characterized in that: The calculation formula of the state space equation of the permanent magnet synchronous motor is as follows: in, , They are x 1. x The first derivative of 2, , , x 1 is the speed error of the permanent magnet synchronous motor, x 2 for x The first derivative of 1, ω ref is the reference speed of the permanent magnet synchronous motor, ω m is the mechanical angular velocity, is the first-order derivative of the mechanical angular velocity, D is the coefficient of the control input, u is the permanent magnet synchronous motor control input and is the sliding mode controller output.

6. The sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to claim 1 is characterized in that: The sliding mode control law of the permanent magnet synchronous motor is established according to the state space mathematical model of the permanent magnet synchronous motor, including: S2-1, obtain a new speed exponential reaching law and sliding film surface function of the speed loop sliding mode controller of the permanent magnet synchronous motor; S2-2. According to the state space mathematical model of the permanent magnet synchronous motor, the sliding mode control law of the permanent magnet synchronous motor is obtained by utilizing the novel speed exponential approach law and sliding film surface function of the speed loop sliding mode controller of the permanent magnet synchronous motor.

7. The sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to claim 6 is characterized in that: The calculation formula of the novel variable exponential reaching law of the permanent magnet synchronous motor speed loop sliding mode controller is as follows: in, is the first-order derivative of the sliding surface, ε is the coefficient of the constant velocity approach term, F ( x,t ) is the additional function of the variable speed approach term, x is the state variable of the permanent magnet synchronous motor system, t is time, tanh(▪) is the additional function of the variable exponential approach term, s is the sliding surface function, k is the exponential approach coefficient, G ( s ) is the additional function of the variable exponential approach term, α is a constant.

8. The sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to claim 6 is characterized in that: The calculation formula of the sliding mode surface function of the permanent magnet synchronous motor speed loop sliding mode controller is as follows: in, s is the sliding surface function, C is a constant greater than zero, x 1 is the speed error of the permanent magnet synchronous motor, x 2 for x The first derivative of 1.

9. The sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to claim 6 is characterized in that: The calculation formula of the sliding mode control law of the permanent magnet synchronous motor is as follows: in, i q_NewEAL is the output of the sliding mode controller, D is the coefficient of the control input, t For time, C is a constant greater than zero, x 1 is the speed error of the permanent magnet synchronous motor, ε is the coefficient of the constant velocity approach term, F ( x,t ) is the additional function of the variable speed approach term, x is the state variable of the permanent magnet synchronous motor system, tanh(▪) is the additional function of the variable exponential approach term, s is the sliding surface function, k is the exponential approach coefficient, G ( s ) is an additional function of the variable exponential approach term.

10. The sliding mode control method of a permanent magnet synchronous motor based on a novel speed exponential reaching law according to claim 8, characterized in that: The sliding mode control results of the permanent magnet synchronous motor are obtained based on the Lyapunov function using the sliding mode control law of the permanent magnet synchronous motor, including: S3-1, constructing a Lyapunov function according to the sliding surface function of the permanent magnet synchronous motor speed loop sliding mode controller; S3-2. Based on the Lyapunov function, a derivative value of the Lyapunov function is obtained according to the state space mathematical model of the permanent magnet synchronous motor as a sliding mode control result of the permanent magnet synchronous motor.

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