Permanent magnet synchronous motor control method for adaptively adjusting thickness of boundary layer

Abstract

The invention relates to a permanent magnet synchronous motor control method capable of adaptively adjusting the thickness of a boundary layer. The method comprises the following steps: establishing a mathematical function of a sliding mode switching surface according to a permanent magnet synchronous motor control variable; establishing a nonlinear boundary layer represented by a saturation function based on a ratio of a boundary layer thickness controlled by a sliding mode switching surface and a sliding mode variable structure as an independent variable; the boundary layer thickness controlled by the sliding mode variable structure is obtained by adopting a fuzzy control algorithm to carry out self-adaptive adjustment; derivation is carried out on the mathematical function of the sliding mode switching surface, and a sliding mode variable structure control law is established based on the mathematical function of the sliding mode switching surface after derivation in combination with the sliding mode switching surface and a nonlinear boundary layer represented by a saturation function; and performing vector control on the permanent magnet synchronous motor based on the sliding mode variable structure control law. The nonlinear boundary layer designed by the invention solves the problem of system buffeting caused by control input discontinuity, and the thickness of the boundary layer controlled by the sliding mode variable structure is adaptively adjusted, so that the robustness is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and particularly relates to a control method for a permanent magnet synchronous motor with adaptive adjustment of boundary layer thickness. Background Art

[0002] The three-phase permanent magnet synchronous motor (PMSM) is a rotating motor driven by a three-phase AC power supply, which has the advantages of high efficiency, high reliability, low noise, etc. The three-phase PMSM motor is widely used in industries, agriculture, transportation, construction and other fields, and is an indispensable power equipment in modern society. The purpose of controlling the three-phase PMSM motor is to adjust the speed, torque and power of the motor according to the load demand. Different load types and working conditions require different control methods and controllers. The control technology of the three-phase PMSM motor is a highly comprehensive discipline, which involves multiple fields such as motor theory, power electronics, automatic control, signal processing, microprocessor, etc.

[0003] Common control methods for three-phase PMSM motors include the switching control method, the transformer control method, the variable frequency control method and the vector control method.

[0004] Switching control method: This is the simplest control method. By changing the switching state of the power supply, the start, stop, forward and reverse rotation and braking of the motor are controlled. The disadvantage of this method is that both the control accuracy and the response speed are very low, and stepless speed regulation cannot be achieved. Only a few fixed speeds can be realized.

[0005] Transformer control method: This is a control method that uses a transformer to change the voltage of the motor winding. By changing the tap position of the transformer, different speed levels are achieved. The disadvantages of this method are that both the control accuracy and the response speed are relatively low, stepless speed regulation cannot be achieved, only stepped speed regulation can be achieved, and there are problems such as winding loss and core loss.

[0006] Variable frequency control method: This is a control method that uses power electronic devices to change the power supply frequency. By changing the power supply frequency, stepless adjustment of the synchronous speed of the motor is achieved. The disadvantages of this method are high cost, low reliability, and problems such as harmonic interference and switching loss.

[0007] Vector control method: This is a control method that uses a mathematical model to decompose and synthesize the stator current of the motor. By independently controlling the motor magnetic field and torque, precise adjustment of the motor speed and torque is achieved. The disadvantage is that the most common control strategy used in the vector control algorithm is the PID algorithm. The PID algorithm requires the design of PID parameters. Although there are already particle algorithms for automatically calculating PID parameters, there are problems of poor robustness and system chattering caused by the discontinuity of the control input.

[0008] In summary, traditional control algorithms and strategies are relatively simple and cannot adaptively identify and adjust important parameters during the operation of the motor, resulting in the defect of weak robustness. In addition, they cannot effectively reduce the speed fluctuation, resulting in discontinuity of the control input and system chattering phenomenon. Summary of the Invention

[0009] In order to solve the problems of system chattering and poor robustness existing in the existing motor control algorithms, the present invention provides a control method for a permanent magnet synchronous motor with adaptive adjustment of the boundary layer thickness. By designing a non-linear boundary layer, it solves the problem of system chattering caused by the discontinuity of the control input, and adaptively adjusts the boundary layer thickness of the sliding mode variable structure control to improve the robustness.

[0010] In order to achieve the above object, the technical scheme adopted by the present invention is as follows:

[0011] A control method for a permanent magnet synchronous motor with adaptive adjustment of the boundary layer thickness, the method includes the following steps:

[0012] Establish a mathematical function of the sliding mode switching surface according to the control variables of the permanent magnet synchronous motor;

[0013] Based on the ratio of the sliding mode switching surface to the boundary layer thickness of the sliding mode variable structure control as the independent variable, establish a non-linear boundary layer represented by a saturation function;

[0014] The boundary layer thickness of the sliding mode variable structure control is adaptively adjusted by using a fuzzy control algorithm;

[0015] Derive the mathematical function of the sliding mode switching surface, and based on the derived mathematical function of the sliding mode switching surface, combine the sliding mode switching surface and the non-linear boundary layer represented by the saturation function to establish a sliding mode variable structure control law;

[0016] Based on the established sliding mode variable structure control law, perform vector control on the permanent magnet synchronous motor.

[0017] The present invention uses the idea of the boundary layer method (quasi-sliding mode method) to reduce chattering. Based on the ratio of the sliding mode switching surface to the boundary layer thickness of the sliding mode variable structure control as the independent variable, a non-linear boundary layer represented by a saturation function is established, and a sliding mode variable structure control law is established accordingly. The chattering phenomenon of the controlled system can be effectively reduced through the saturation function. The present invention also adaptively adjusts the boundary layer thickness of the sliding mode variable structure control by fuzzy control, so that the established sliding mode variable structure control law has strong control robustness. By adaptively adjusting the boundary layer thickness of the sliding mode variable structure control, the control accuracy and response speed of the three-phase permanent magnet synchronous motor can be effectively improved.

[0018] Preferably, the establishment of the mathematical function of the sliding mode switching surface according to the control variables of the permanent magnet synchronous motor includes:

[0019] The angular velocity variable for the speed control of a permanent magnet synchronous motor is obtained from the torque equation and the mechanical motion equation of the permanent magnet synchronous motor.

[0020] Based on the angular velocity variable for the speed control of the permanent magnet synchronous motor, a mathematical function of the first sliding mode switching surface is established.

[0021] The present invention can establish a mathematical function of the corresponding sliding mode switching surface according to different control variables of the permanent magnet synchronous motor. In order to distinguish it from the mathematical functions of the sliding mode switching surfaces established by other control variables of the permanent magnet synchronous motor, the present invention establishes a mathematical function of the sliding mode switching surface for the angular velocity variable of the permanent magnet synchronous motor speed control, which is defined as the mathematical function of the first sliding mode switching surface. In the following text, a mathematical function of the sliding mode switching surface is established for the error variable of the permanent magnet synchronous motor position control, which is defined as the mathematical function of the second sliding mode switching surface. The first and the second are only for distinguishing different mathematical functions of the sliding mode switching surfaces.

[0022] Furthermore, the mathematical function of the first sliding mode switching surface is differentiated. Based on the differentiated mathematical function of the first sliding mode switching surface, a sliding mode variable structure speed control law is established in combination with the first sliding mode switching surface and the nonlinear boundary layer represented by the saturation function. The expression of the sliding mode variable structure speed control law is as follows:

[0023]

[0024] Where, J represents the moment of inertia of the motor, represents the magnetic flux generated by the permanent magnet, B represents the friction coefficient, s1 represents the first sliding mode switching surface, represents the saturation function corresponding to the first sliding mode switching surface, φ represents the boundary layer thickness of the sliding mode variable structure control, k = 1 / φ; x1 = ω * - ω e , ω * represents the reference angular velocity of the permanent magnet synchronous motor, ω e represents the electrical angular velocity of the rotor of the permanent magnet synchronous motor, and ω e = pω m , ω m represents the mechanical angular velocity of the rotor of the permanent magnet synchronous motor, p n represents the number of pole pairs of the permanent magnet synchronous motor; c = [c1, c2,... c n-1 , 1] T , c1, c2... c n-1 need to satisfy that p n-1 + c n-1 p n-2 +... + c2p + c1 is a Hurwitz polynomial, p is the Laplace operator; ω represents the mechanical angular velocity of the motor.

[0025] Preferably, the mathematical function for establishing the sliding mode switching surface based on the control variables of the permanent magnet synchronous motor includes:

[0026] Establish a mathematical function of the error variable for the position control of the permanent magnet synchronous motor based on the reference given motor rotor position signal and the actual motor rotor position signal of the permanent magnet synchronous motor;

[0027] Differentiate the mathematical function of the error variable for the position control of the permanent magnet synchronous motor, and establish a mathematical function of the second sliding mode switching surface in combination with the error variable for the position control of the permanent magnet synchronous motor.

[0028] Furthermore, differentiate the mathematical function of the second sliding mode switching surface, and based on the differentiated mathematical function of the second sliding mode switching surface, establish a sliding mode variable structure position control law in combination with the second sliding mode switching surface and the nonlinear boundary layer represented by the saturation function. The expression of the sliding mode variable structure position control law is as follows:

[0029]

[0030] In the formula, J represents the moment of inertia of the motor, represents the magnetic flux generated by the permanent magnet, B represents the friction coefficient, s2 represents the second sliding mode switching surface, represents the saturation function corresponding to the second sliding mode switching surface, φ represents the boundary layer thickness of the sliding mode variable structure control, k = 1 / φ; x1 = ω * -ω e , ω * represents the reference angular velocity of the permanent magnet synchronous motor, ω e represents the electrical angular velocity of the permanent magnet synchronous motor rotor, and ω e = pω m , ω m represents the mechanical angular velocity of the permanent magnet synchronous motor rotor, p n represents the number of pole pairs of the permanent magnet synchronous motor; c = [c1, c2,... c n-1 ,1] T , c1, c2... c n-1 need to satisfy that p n-1 + c n-1 p n-2 +... + c2p + c1 is a Hurwitz polynomial, and p is the Laplace operator; represents the derivative obtained by differentiating the mathematical function of the position error variable of the permanent magnet synchronous motor system, represents the first derivative of the actual motor rotor position fed back by the permanent magnet synchronous motor; represents the second derivative of the reference given command position of the permanent magnet synchronous motor.

[0031] Furthermore, the expression of the boundary layer thickness of the sliding mode variable structure control is as follows:

[0032] φ = nφ1+(1 - n)φ2 (10)

[0033] where n = n0 + d n , n0 = 0.5, and the coefficient d n is obtained by taking the sliding mode switching surface as the control variable input of the fuzzy control algorithm into the fuzzy control algorithm, -0.5 ≤ d n ≤ 0.5 and 0 ≤ n ≤ 1; φ1 and φ2 represent two different boundary layer thickness values set according to the permanent magnet synchronous motor system, satisfying 0 < φ1 < φ2; when the coefficient n approaches 1, the boundary layer thickness is closer to φ1; when n approaches 0, the boundary layer thickness is closer to φ2.

[0034] Furthermore, the coefficient d n is obtained by taking the sliding mode switching surface as the input variable of the fuzzy control algorithm into the fuzzy control algorithm, including:

[0035] Taking the absolute value of the distance from the state point in the system state space to the sliding mode switching surface as the input variable of the fuzzy control algorithm;

[0036] Or taking the absolute value of the distance from the state point in the system state space to the sliding mode switching surface and the absolute value of the speed of the state point in the system state space to the sliding mode switching surface as the input variables of the fuzzy control algorithm;

[0037] Or taking the absolute value of the distance from the state point in the system state space to the sliding mode switching surface, the absolute value of the speed of the state point in the system state space to the sliding mode switching surface, and the absolute value of the acceleration of the state point in the system state space to the sliding mode switching surface as the input variables of the fuzzy control algorithm;

[0038] Thus, the fuzzy control algorithm adjusts the coefficient d n according to the real-time state of the controlled system to achieve adaptive fuzzy adjustment of the boundary layer thickness of the sliding mode variable structure control.

[0039] Furthermore, the fuzzy control algorithm includes a one-dimensional fuzzy control algorithm, a two-dimensional fuzzy control algorithm, and a three-dimensional fuzzy control algorithm; the corresponding fuzzy control algorithm is selected according to the number of input variables of the fuzzy control algorithm.

[0040] Furthermore, the conditions for achieving adaptive fuzzy adjustment of the boundary layer thickness of the sliding mode variable structure control include the following:

[0041] When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface is greater than the threshold φ2, the fuzzy control algorithm increases the boundary layer thickness of the sliding mode variable structure control to make the state point approach the sliding mode switching surface;

[0042] When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface is less than φ2 and greater than φ1, the state point is located in the middle region at this time, and the fuzzy control algorithm reduces the boundary layer thickness of the sliding mode variable structure control.

[0043] When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface is less than φ1, the state point has three states: moving on the sliding mode switching surface S = 0, moving in the left region of the sliding mode switching surface, and moving in the right region of the sliding mode switching surface.

[0044] An electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the permanent magnet synchronous motor control method for adaptive adjustment of the boundary layer thickness as described above.

[0045] A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, it implements the permanent magnet synchronous motor control method for adaptive adjustment of the boundary layer thickness as described above.

[0046] Advantages of the present invention:

[0047] For a permanent magnet synchronous motor control system, if based on a traditional sliding mode variable structure control system, there will be a phenomenon of system chattering caused by the discontinuity of the control input. The present invention uses the idea of the boundary layer method (quasi-sliding mode method) to reduce chattering, and based on the ratio of the sliding mode switching surface to the boundary layer thickness of the sliding mode variable structure control as the independent variable, a non-linear boundary layer represented by a saturation function is established, and thus a sliding mode variable structure control law is established, which can effectively reduce the chattering phenomenon of the controlled system. The present invention also adaptively adjusts the boundary layer thickness of the sliding mode variable structure control by fuzzy control, so that the established sliding mode variable structure control law has strong control robustness. By adaptively adjusting the boundary layer thickness of the sliding mode variable structure control, the control accuracy and response speed of the three-phase permanent magnet synchronous motor can be effectively improved. Description of the drawings

[0048] Figure 1 It is a schematic diagram of the equal-speed approaching law in the speed sliding mode variable structure control law based on the exponential approaching law in the prior art.

[0049] Figure 2 It is a schematic diagram of the saturation function sat(s).

[0050] Figure 3 It is a flowchart of the permanent magnet synchronous motor control method for adaptive adjustment of the boundary layer thickness according to the present invention.

[0051] Figure 4 It is a schematic diagram of the one-dimensional, two-dimensional, and three-dimensional fuzzy control algorithms according to the present invention.

[0052] Figure 5 This is the principle block diagram of the permanent magnet synchronous motor control method with adaptive adjustment of the boundary layer thickness according to the present invention.

[0053] Figure 6 This is the system diagram of the fuzzy control algorithm.

[0054] Figure 7 This is the schematic diagram of the membership function of the input variable |s|.

[0055] Figure 8 This is the schematic diagram of the membership function of the input variable |ds / dt|.

[0056] Figure 9 This is the schematic diagram of the membership function of the output variable dn.

[0057] Figure 10 This is the 3D mesh diagram of the fuzzy surface. Detailed implementation manners

[0058] The following will illustrate the implementation manners of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention rather than for limiting the protection scope of the present invention.

[0059] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0060] In this embodiment, the sliding mode variable structure control mentioned below is a discontinuous variable structure control. The structure of the control system can exhibit specific switching characteristics over time. This specific switching characteristic causes the control to be discontinuous, making the state trajectory of the controlled system move along a specific state trajectory with small amplitude and high frequency. This movement is the "sliding mode movement" of the sliding mode variable structure control.

[0061] The sliding mode refers to the state in which the actual state trajectory of the control system moves within the neighborhood φ (within the boundary layer) of a pre-designed target state trajectory. When the controlled system enters the sliding mode region, the state points of the system will continuously move within the sliding mode and reach the equilibrium point within a finite time. The movement of the system state points approaching the equilibrium point is called the sliding mode movement.

[0062] However, in traditional sliding mode variable structure control, the boundary layer thickness within the neighborhood φ (inside the boundary layer, φ is called the boundary layer thickness of sliding mode variable structure control) is a fixed value and cannot be adaptively identified and adjusted. As a result, the robustness is weak, and the control accuracy and response speed of the three-phase permanent magnet synchronous motor cannot be improved well.

[0063] Before explaining the permanent magnet synchronous motor control method with adaptive adjustment of the boundary layer thickness according to the present invention, a sliding mode variable structure speed control method based on the exponential reaching law is introduced as follows:

[0064] Generally, assume the expression of the sliding mode switching surface is as follows:

[0065]

[0066] where x is the system state vector, C = [c1, c2,... c n-1 ,1] T is one of the parameters to be designed for the sliding mode variable structure control law; c1, c2... c n-1 satisfy the Hurwitz polynomial p n-1 + c n-1 p n-2 +... + c2p + c1, and p is the Laplace operator.

[0067] From the torque equation of the permanent magnet synchronous motor and the mechanical motion equation of the permanent magnet synchronous motor, the state variables for the speed control of the permanent magnet synchronous motor are obtained, and their expressions are:

[0068]

[0069] where ω * represents the reference angular velocity of the permanent magnet synchronous motor, which is a constant; ω e represents the electrical angular velocity of the rotor of the permanent magnet synchronous motor, and ω e = pω m , ω m represents the mechanical angular velocity of the rotor of the permanent magnet synchronous motor, p represents the number of pole pairs of the permanent magnet synchronous motor, and t represents time.

[0070] Taking the derivative of Equation (2) gives:

[0071]

[0072] where J represents the moment of inertia of the motor; represents the magnetic flux generated by the permanent magnet; T L represents the load torque of the motor; B represents the friction coefficient; i q represents a component obtained by decoupling the current of the motor; ω represents the mechanical speed of the motor; It is obtained by taking the first derivative of the electrical angular velocity of the permanent magnet synchronous motor rotor.

[0073] Let d be the disturbance caused by the change of the system load or the external environment, and it satisfies |d| ≤ η; η represents the upper bound of the disturbance.

[0074] Then, according to the state variables of the permanent magnet synchronous motor speed control, the mathematical function of the sliding mode switching surface s is established, and its expression is:

[0075] s = x1 + cx2 (4)

[0076] Taking the derivative of the mathematical function of the sliding mode switching surface s, we get:

[0077]

[0078] Among them, c > 0 is one of the parameters to be designed in the sliding mode variable structure control algorithm and is a constant.

[0079] Using the exponential reaching law for the design of the sliding mode variable structure control algorithm, the speed sliding mode variable structure control law based on the exponential reaching law is:

[0080]

[0081] Such as Figure 1 shown, it is the constant speed reaching rate Among them, ε > 0. From ε·sign(s), it can be seen that when the sliding mode switching surface s changes near 0, it will cause the discontinuity of the constant speed reaching law, resulting in the change of the structure of the control algorithm. When the values of s > 0 or s < 0 change greatly, in the actual control of PMSM, it will cause the sudden change of the control input quantity, resulting in the instability of the controlled object. Therefore, it cannot reduce the speed fluctuation and overshoot well, and cannot improve the steady-state and dynamic performance well.

[0082] Therefore, aiming at the above problems, the boundary layer method (quasi-sliding mode method) can be used to reduce the chattering problem. The boundary layer method (quasi-sliding mode method) used to reduce the chattering problem is that all state points within a certain φ neighborhood (φ is called the boundary layer thickness of the sliding mode variable structure control) near the artificially designed sliding mode switching surface S(x) = 0 can reach the designed sliding mode switching surface within a finite time. When using the quasi-sliding mode method to reduce the system chattering, the sign function sign(s) in the sliding mode reaching law is replaced by the saturation function sat(s). In the boundary layer of the sliding mode variable structure control, the saturation function sat(s) is defined as follows:

[0083]

[0084] Among them, k = 1 / φ, so the quasi-sliding mode method is also known as the boundary layer method. The saturation function sat(s) makes the output variable of the sliding mode variable structure control strategy continuously change within the boundary layer without structural transformation.

[0085] As Figure 2 shown, outside the φ neighborhood (|s≥φ) near the sliding mode switching surface S(x)=0, sliding mode variable structure switching control is adopted. While within the boundary layer thickness (|s<φ), linear feedback control with a control gain that changes in real time with the system state is adopted. Although this method essentially weakens the chattering phenomenon of the system to a certain extent, the boundary layer thickness cannot be adaptively adjusted, resulting in poor robustness.

[0086] Therefore, as Figure 3 shown in this embodiment, a permanent magnet synchronous motor control method with adaptive adjustment of the boundary layer thickness is provided. The method includes the following steps:

[0087] Establish a mathematical function of the sliding mode switching surface according to the control variables of the permanent magnet synchronous motor;

[0088] Based on the ratio of the sliding mode switching surface and the boundary layer thickness of the sliding mode variable structure control as the independent variable, establish a non-linear boundary layer represented by the saturation function;

[0089] The boundary layer thickness of the sliding mode variable structure control is obtained by adaptive adjustment using the fuzzy control algorithm;

[0090] Derive the mathematical function of the sliding mode switching surface. Based on the derived mathematical function of the sliding mode switching surface, combine the sliding mode switching surface and the non-linear boundary layer represented by the saturation function to establish a sliding mode variable structure control law;

[0091] Based on the established sliding mode variable structure control law, perform vector control on the permanent magnet synchronous motor.

[0092] In this embodiment, establishing the mathematical function of the sliding mode switching surface according to the control variables of the permanent magnet synchronous motor includes:

[0093] Obtain the angular velocity variable for permanent magnet synchronous motor speed control from the torque equation of the permanent magnet synchronous motor and the mechanical motion equation of the permanent magnet synchronous motor. Its expression is:

[0094]

[0095] Among them, ω * represents the reference angular velocity of the permanent magnet synchronous motor, which is a constant; ω e represents the electrical angular velocity of the rotor of the permanent magnet synchronous motor, and ω e = pω m , ω mω represents the mechanical angular velocity of the permanent magnet synchronous motor rotor, p represents the number of pole pairs of the permanent magnet synchronous motor, and t represents time.

[0096] Let d be the disturbance caused by the change of system load or external environment, and satisfy |d|≤η; η represents the upper bound of the disturbance;

[0097] Then, according to the angular velocity variable of the permanent magnet synchronous motor speed control, a mathematical function of the first sliding mode switching surface is established, and its expression is:

[0098] s1 = x1 + cx2 (9)

[0099] Taking the ratio of the boundary layer thickness based on the sliding mode switching surface and the sliding mode variable structure control as the independent variable, a nonlinear boundary layer represented by a saturation function is established, and its expression is as follows:

[0100]

[0101] In the formula, d represents the disturbance caused by the change of system load or external environment, and satisfies |d|≤η; η represents the upper bound of the disturbance;

[0102] The rewritten form of formula (10) is as follows:

[0103]

[0104] Among them: φ is the boundary layer thickness of the sliding mode variable structure control, φ>0; 0<h<1, h = m / n, and m, n are positive odd numbers, and s1 represents the first sliding mode switching surface.

[0105] In this embodiment, the mathematical function of the first sliding mode switching surface is differentiated. Based on the differentiated mathematical function of the first sliding mode switching surface, a sliding mode variable structure control law is established by combining the first sliding mode switching surface and the nonlinear boundary layer represented by the saturation function, including:

[0106] Differentiating formula (8) gives:

[0107]

[0108] Among them, J represents the moment of inertia of the motor; represents the magnetic flux generated by the permanent magnet; T L represents the load torque of the motor; B represents the friction coefficient; ω represents the mechanical speed of the motor.

[0109] Differentiating the mathematical function of the first sliding mode switching surface gives:

[0110]

[0111] Among them, c>0 is one of the parameters to be designed for the sliding mode variable structure control algorithm and is a constant.

[0112] Based on the mathematical function of the first sliding mode switching surface obtained by differentiation (Equation (13)), combined with the designed mode switching surface and the non-linear boundary layer represented by the saturation function, a sliding mode variable structure speed control law is established, and its expression is as follows;

[0113]

[0114] where J represents the moment of inertia of the motor, represents the magnetic flux generated by the permanent magnet, B represents the friction coefficient, s1 represents the first sliding mode switching surface, represents the saturation function corresponding to the first sliding mode switching surface, φ represents the boundary layer thickness of the sliding mode variable structure control, k = 1 / φ; x1 = ω * - ω e ω * represents the reference angular velocity of the permanent magnet synchronous motor, ω e represents the electrical angular velocity of the rotor of the permanent magnet synchronous motor, and ω e = pω m ω m represents the mechanical angular velocity of the rotor of the permanent magnet synchronous motor, p n represents the number of pole pairs of the permanent magnet synchronous motor; c = [c1, c2,... c n-1 , 1] T , c1, c2... c n-1 need to satisfy p n-1 + c n-1 p n-2 +... + c2p + c1 is a Hurwitz polynomial, p is the Laplace operator; ω represents the mechanical speed of the motor.

[0115] In this embodiment, vector control of the permanent magnet synchronous motor is performed based on the established sliding mode variable structure speed control law.

[0116] Compared with the speed sliding mode variable structure control method based on the exponential reaching law, the sliding mode variable structure speed control law described in the present invention is obtained by replacing the sign function sign(s) in the exponential reaching law control method (Equation (6)) with the saturation function sat(s / φ) of Equation (11).

[0117] In another embodiment, the mathematical function for establishing the sliding mode switching surface according to the control variables of the permanent magnet synchronous motor includes:

[0118] A mathematical function of the error variable for position control of the permanent magnet synchronous motor is established based on the reference given motor rotor position signal and the actual motor rotor position signal of the permanent magnet synchronous motor. Among them, the mathematical function of the error variable of the permanent magnet synchronous motor system is:

[0119] e x = θ - θ d (15)

[0120] where, θ d is the reference given command position of the permanent magnet synchronous motor, which is a constant; θ is the actual motor rotor position feedback by the permanent magnet synchronous motor.

[0121] Derive the mathematical function of the error variable of the permanent magnet synchronous motor position control, and establish the mathematical function of the second sliding mode switching surface in combination with the error variable of the permanent magnet synchronous motor position control, where the mathematical function of the second sliding mode switching surface is:

[0122]

[0123] In the formula: the coefficient c is one of the parameters to be designed and tuned for the sliding mode variable structure control algorithm, which is a constant; represents the derivative obtained by deriving the mathematical function of the error variable of the permanent magnet synchronous motor system.

[0124] Derive the mathematical function of the second sliding mode switching surface, and based on the derived mathematical function of the second sliding mode switching surface, establish a sliding mode variable structure control law in combination with the second sliding mode switching surface and the nonlinear boundary layer represented by the saturation function, including:

[0125] The motor angular displacement variable for the permanent magnet synchronous motor position control is obtained from the torque equation and mechanical motion equation of the permanent magnet synchronous motor, and its expression is as follows:

[0126]

[0127] Let d be the disturbance caused by the change of the system load or external environment and satisfy |d|≤η; η is the upper bound of the disturbance, then the rewritten form of formula (17) is:

[0128]

[0129] Derive formula (16) to get:

[0130]

[0131] Establish a sliding mode variable structure position control law in combination with the derived mathematical function of the second sliding mode section surface (formula (19)), the second sliding mode switching surface, and the nonlinear boundary layer represented by the saturation function, where the expression of the sliding mode variable structure position control law is as follows:

[0132]

[0133] In the formula, J represents the moment of inertia of the motor, represents the magnetic flux generated by the permanent magnet, B represents the friction coefficient, s2 represents the first sliding mode switching surface, Denote the saturation function corresponding to the second sliding mode cutting plane, φ denote the boundary layer thickness of the sliding mode variable structure control, k = 1 / φ; x1 = ω * -ω e , ω * denote the reference angular velocity of the permanent magnet synchronous motor, ω e denote the electrical angular velocity of the rotor of the permanent magnet synchronous motor, and ω e = pω m , ω m denote the mechanical angular velocity of the rotor of the permanent magnet synchronous motor, p n denote the number of pole pairs of the permanent magnet synchronous motor; c = [c1, c2, … c n-1 , 1] T , c1, c2 … c n-1 need to satisfy p n-1 + c n-1 p n-2 + … + c2p + c1 is a Hurwitz polynomial, p is the Laplace operator; denote the derivative obtained by differentiating the mathematical function of the position error variable of the permanent magnet synchronous motor system, denote the first derivative of the actual motor rotor position feedback by the permanent magnet synchronous motor, denote the second derivative of the reference given command position of the permanent magnet synchronous motor.

[0134] This embodiment performs vector control on the permanent magnet synchronous motor based on the established sliding mode variable structure position control law.

[0135] In this embodiment, since the values of the saturation function for x > 0 and x < 0 are continuous and there will be no structural change. Although the smoothness of the control law on both sides of the sliding mode switching surface (both sides of s > 0 and S < 0) is effectively improved after adding the saturation function, the response speed is insufficient. Therefore, this embodiment introduces a fuzzy control algorithm to adaptively adjust the boundary layer thickness in real time.

[0136] In the above embodiment, the boundary layer thickness of the sliding mode variable structure control is adaptively adjusted by using a fuzzy control algorithm. Specifically, the expression of the boundary layer thickness of the sliding mode variable structure control is as follows:

[0137] φ = nφ1 + (1 - n)φ2 (21)

[0138] In the formula, n = n0 + d n , n0 = 0.5, the coefficient d n denote the input of the sliding mode switching surface as the control variable of the fuzzy control algorithm to the fuzzy control algorithm, -0.5 ≤ d n≤0.5 and 0 ≤ n ≤ 1; φ1 and φ2 represent two different boundary layer thickness values set according to the permanent magnet synchronous motor system, and their values are obtained by the empirical trial-and-error method and satisfy 0 < φ1 < φ2; when the coefficient n is close to 1, the boundary layer thickness is closer to φ1; when n is close to 0, the boundary layer thickness is closer to φ2.

[0139] Coefficient d n It is obtained by taking the sliding mode switching surface as the input variable of the fuzzy control algorithm and inputting it into the fuzzy control algorithm, including:

[0140] Taking the absolute value of the distance from the state point in the system state space to the sliding mode switching surface as the input variable of the fuzzy control algorithm;

[0141] Or taking the absolute value of the distance from the state point in the system state space to the sliding mode switching surface and the absolute value of the speed of the state point in the system state space to the sliding mode switching surface as the input variables of the fuzzy control algorithm;

[0142] Or taking the absolute value of the distance from the state point in the system state space to the sliding mode switching surface, the absolute value of the speed of the state point in the system state space to the sliding mode switching surface, and the absolute value of the acceleration of the state point in the system state space to the sliding mode switching surface as the input variables of the fuzzy control algorithm;

[0143] Thus, the fuzzy control algorithm adjusts the coefficient d n to achieve adaptive fuzzy adjustment of the boundary layer thickness of the sliding mode variable structure control.

[0144] The detailed design of the fuzzy control algorithm in this embodiment is as follows:

[0145] The input variable of the fuzzy control algorithm is generally the difference between the reference given value and the actual feedback value of the system. However, in the boundary layer thickness adaptive adjustment fuzzy control algorithm designed in the present invention, the control variable of the sliding mode controller is not the error value between the target given value and the system feedback, but the sliding mode switching surface.

[0146] The fuzzy control algorithm includes a one-dimensional fuzzy control algorithm, a two-dimensional fuzzy control algorithm, and a three-dimensional fuzzy control algorithm; select the corresponding fuzzy control algorithm according to the number of input variables of the fuzzy control algorithm, as Figure 4 shown.

[0147] When taking the absolute value of the distance from the state point in the system state space to the sliding mode switching surface as the input variable of the fuzzy control algorithm, the fuzzy control algorithm selects a one-dimensional fuzzy control algorithm.

[0148] When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface and the absolute value of the velocity of the state point in the system state space to the sliding mode switching surface are used as the input variables of the fuzzy control algorithm, the fuzzy control algorithm selects a two-dimensional fuzzy control algorithm.

[0149] When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface, the absolute value of the velocity of the state point in the system state space to the sliding mode switching surface, and the absolute value of the acceleration of the state point in the system state space to the sliding mode switching surface are used as the input variables of the fuzzy control algorithm; the fuzzy control algorithm selects a three-dimensional fuzzy control algorithm.

[0150] The velocity of the state point in the system state space to the sliding mode switching surface is obtained by taking the first derivative of the distance from the state point in the system state space to the sliding mode switching surface; the acceleration of the state point in the system state space to the sliding mode switching surface is obtained by taking the derivative of the velocity of the state point in the system state space to the sliding mode switching surface.

[0151] In this embodiment, the absolute value of the distance |s| from the state point in the system state space to the sliding mode switching surface and the absolute value of the velocity |ds / dt| of the state point in the system state space to the sliding mode switching surface are selected as the input variables of the fuzzy control algorithm; both the change of the distance |s| from the system state point to the sliding mode switching surface and the change of the velocity |ds / dt| when the state point slides along the sliding mode and approaches the sliding mode switching surface are considered. Coefficient d n is the output variable of the sliding mode controller, and the fuzzy control algorithm adjusts the coefficient d according to the real-time state of the controlled system n Therefore, a two-dimensional fuzzy control algorithm is selected in this embodiment.

[0152] In this embodiment, the boundary layer thickness of the sliding mode variable structure control is adaptively and fuzzily adjusted, and the following principles are followed:

[0153] The first threshold and the second threshold divide the space of the sliding mode switching surface into three regions, namely, the region farthest from the sliding mode switching surface, the middle region, and the nearest region.

[0154] a) When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface is greater than the first threshold, at this time the state point is far from the sliding mode switching surface and is located in the farthest region. At this time, the designed controller increases the boundary layer thickness of the sliding mode variable structure control, so that the state point can approach the sliding mode switching surface faster;

[0155] b) When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface is less than the first threshold and greater than the second threshold, the state point is at this time in the intermediate region. To prevent the boundary layer thickness from being too large, resulting in too large a control input of the system, so that after the state point crosses the sliding mode switching surface, there is still a large control input, leading to a deterioration of the system's steady state. Therefore, the designed controller will appropriately reduce the boundary layer thickness of the sliding mode variable structure control.

[0156] c) When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface is less than the second threshold, the state point is at this time in the nearest region. At this time, the state point has three states: (1) moving on the sliding mode switching surface, that is, moving on S = 0; (2) moving in the right region of the sliding mode switching surface, that is, moving in the region where S>0; (3) moving in the left region of the sliding mode switching surface, that is, moving in the region where S<0.

[0157] The sliding mode motion is a motion process that continuously approaches the sliding mode switching surface S = 0. When the state point approaches the sliding mode switching surface more, the steady state and robustness of the system are stronger. Therefore, the designed controller will further reduce the boundary layer thickness of the sliding mode variable structure control, so that the state point in the system state space moves in a smaller region on both sides of the sliding mode switching surface S = 0, thereby obtaining better control accuracy.

[0158] To verify the effectiveness and feasibility of the sliding mode variable structure position control law and the sliding mode variable structure speed control law established in the present invention, the following analysis is carried out:

[0159] 1) For any state point outside the boundary layer There is sat(s / φ) = sign(s), and we get:

[0160]

[0161] where ε > η > |d| and k > 0, s·sign(s) = |s|;

[0162] Since It can be obtained that the sliding mode variable structure position control law and the sliding mode variable structure speed control law satisfy the Lyapunov condition, and the method described in the present invention satisfies the sliding mode reachability condition, which can ensure that any state point located outside the boundary layer moves into the boundary layer under the action of the sliding mode control.

[0163] 2) For any state point inside the boundary layer There is sat(s / φ) = (s / φ) h , and we get:

[0164]

[0165] From Equation (23), we get:

[0166]

[0167] Also, since 0 < h < 1 and h = m / n, we have:

[0168]

[0169] From Equation (25), since -k·s 2 is always less than zero and ε > η > |d|, k > 0. Therefore, as long as the following conditions are met:

[0170]

[0171] When the conditions of Equation (26) are satisfied, we can obtain That is, the sliding mode variable structure position control law and the sliding mode variable structure speed control law satisfy the Lyapunov conditions. Therefore, the method described in the present invention satisfies the sliding mode reachability condition.

[0172] Furthermore, Equation (26) is transformed into:

[0173]

[0174] When h = 1, |s| ≤ (η / φ)·φ, where ε > η and is a constant. Then the boundary layer at this time is the traditional linear boundary layer.

[0175] Also, because the parameter ε > η, the non-linear boundary layer adopted in the present invention can make the state points of the system move to a smaller area near the sliding mode switching surface. The thickness of the boundary layer of this smaller area is (η / φ)·φ (φ > η and both are constants), thereby obtaining higher control accuracy.

[0176] As Figure 5 shown, it is a simple principle framework diagram of the permanent magnet synchronous motor control method with adaptive adjustment of the boundary thickness according to the present invention. According to Figure 5 it can be known that first, according to the encoder and current sensor, the mechanical angle of the permanent magnet synchronous motor and the three-phase current of the motor are used to establish the torque equation of the permanent magnet synchronous motor and the mechanical motion equation of the permanent magnet synchronous motor, and the control variables of the permanent magnet synchronous motor are obtained therefrom; the control variables of the permanent magnet synchronous motor are combined with the sliding mode switching surface and the non-linear boundary layer represented by the saturation function to establish the sliding mode variable structure control law (that is, the improved sliding mode variable structure control algorithm). The thickness of the boundary layer in establishing the sliding mode variable structure control law is adaptively and fuzzily adjusted according to the absolute value of the distance from the state point in the system state space to the sliding mode switching surface and the absolute value of the speed of the state point in the system state space to the sliding mode switching surface. Finally, vector control is performed on the permanent magnet synchronous motor according to the established sliding mode variable structure speed control law.

[0177] In this embodiment, the established sliding mode variable structure speed control law, sliding mode variable structure position control law are combined with the boundary layer thickness of adaptive fuzzy regulation. By adaptively fuzzy regulating the boundary layer thickness, the chattering phenomenon of the controlled system can be effectively reduced, and the sliding mode variable structure control can also have strong control robustness.

[0178] In this embodiment, the fuzzy control algorithm is as Figure 6 shown, which is a fuzzy control algorithm model of double input and single output.

[0179] The designed fuzzy control algorithm adaptively adjusts the boundary layer thickness of the sliding mode variable structure control strategy according to the real-time state of the system. The input variables |s| and |ds / dt| are respectively defined with 3 fuzzy states, namely "Small (S)", "Medium (M)", "Big (B)", and their fuzzy universes are respectively defined as {0, 0.5, 1, 1.5, 2, 2.5, 3} and {0, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000}; the output variable dn is defined with 5 fuzzy states, namely "NB (Negative Big)", "NS (Negative Small)", "ZO (Zero)", "PS (Positive Small)", "PB (Positive Big)", and the fuzzy universe of the output variable is respectively defined as {-0.5, -0.4, -0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.3, 0.4, 0.5}; so in n=n0+dn, n0 = 0.5.

[0180] The membership function graphs designed for the input variables |s| and |ds / dt| and the output variable dn of the fuzzy control algorithm module are as Figure 7 、 8 、Figure 9 shown.

[0181] According to the principle of adaptive fuzzy adjustment of the boundary layer thickness of the sliding mode variable structure, a fuzzy rule table is designed as Table 1.

[0182] Table 1: Fuzzy rule table for the output dn of the fuzzy control algorithm

[0183]

[0184] According to the designed fuzzy rule table, using MATLAB software, the 3D fuzzy surface mesh graph of the mapping between the input variables |s| and |ds / dt| and the output variable dn of the improved sliding mode variable structure control algorithm with adaptive fuzzy regulation of the boundary layer thickness is drawn, as Figure 10 shown. It can be obtained from the 3D mesh graph of the fuzzy surface that the range of the output parameter dn of the designed fuzzy control algorithm is between (-0.5, 0.5). The adaptive fuzzy regulation of the boundary layer thickness proposed by the present invention meets the design requirements and the control strategy is feasible.

[0185] For the permanent magnet synchronous motor control system, based on the traditional sliding mode variable structure control system, aiming at the system chattering phenomenon caused by the discontinuity of the control input in the traditional sliding mode controller, using the boundary layer method (quasi-sliding mode method) to reduce chattering, a non-linear boundary layer is designed, and the design of the inside and outside of the boundary layer of the sliding mode controller containing this non-linear boundary layer and the asymptotic stability verification based on the sliding mode controller are carried out; an adaptive fuzzy regulation of the boundary layer thickness is also designed, thus improving the sliding mode variable structure control strategy.

[0186] According to the mathematical model of the permanent magnet synchronous motor, for the fuzzy control algorithm with adaptive adjustment of the designed boundary layer thickness, modeling verification is carried out in the Matlab tool, and Lyapunov verification is carried out for the permanent magnet synchronous motor control method described in the present invention, and mathematical derivation is given to verify the feasibility of the designed permanent magnet synchronous motor control method.

[0187] In a specific embodiment, an upper computer is also provided, including a memory and a processor, the memory stores a computer program that can run on the processor, and the processor executes the steps of the permanent magnet synchronous motor control method with adaptive adjustment of the boundary layer thickness.

[0188] Among them, the memory and the processor are connected in a bus manner. The bus can include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors and memories together. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits together, which are well known in the art, so they will not be further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be an element or multiple elements, such as multiple receivers and transmitters, and provides a unit for communicating with various other devices on the transmission medium. The data processed by the processor is transmitted on the wireless medium through the antenna. Further, the antenna also receives data and transmits the data to the processor.

[0189] In a specific embodiment, a computer-readable storage medium is also provided, on which a computer program is stored, and when the computer program is executed by the processor, the steps of the permanent magnet synchronous motor control method with adaptive adjustment of the boundary layer thickness described above are implemented.

[0190] That is, those skilled in the art can understand that all or part of the steps in the methods of the above embodiments can be completed by instructing relevant hardware through a program. The program is stored in a storage medium, including several instructions to enable a device (which can be a single-chip microcomputer, a chip, etc.) or a processor to execute all or part of the steps of the methods described in various embodiments of the present application. The foregoing storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0191] The above embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are within the protection scope of the present invention.

Claims

1. A control method for a permanent magnet synchronous motor with adaptive adjustment of boundary layer thickness, characterized in that: The method includes the following steps: Establish a mathematical function of the sliding mode switching surface according to the control variables of the permanent magnet synchronous motor; Based on the ratio of the sliding mode switching surface and the boundary layer thickness of the sliding mode variable structure control as the independent variable, establish a non-linear boundary layer represented by a saturation function; the boundary layer thickness of the sliding mode variable structure control is adaptively adjusted by using a fuzzy control algorithm; Derive the mathematical function of the sliding mode switching surface, and based on the derived mathematical function of the sliding mode switching surface, establish a sliding mode variable structure control law in combination with the sliding mode switching surface and the non-linear boundary layer represented by the saturation function; Perform vector control on the permanent magnet synchronous motor based on the established sliding mode variable structure control law.

2. The control method of the permanent magnet synchronous motor with adaptive adjustment of boundary layer thickness according to claim 1, characterized in that: The establishment of the mathematical function of the sliding mode switching surface according to the control variables of the permanent magnet synchronous motor includes: Obtain the angular velocity variable for the speed control of the permanent magnet synchronous motor from the torque equation of the permanent magnet synchronous motor and the mechanical motion equation of the permanent magnet synchronous motor; Establish a mathematical function of the first sliding mode switching surface according to the angular velocity variable for the speed control of the permanent magnet synchronous motor.

3. The permanent magnet synchronous motor control method for adaptively adjusting the boundary layer thickness according to claim 2, wherein: Derive the mathematical function of the first sliding mode switching surface, and based on the derived mathematical function of the first sliding mode switching surface, establish a sliding mode variable structure speed control law in combination with the first sliding mode switching surface and the non-linear boundary layer represented by the saturation function, where the expression of the sliding mode variable structure speed control law is as follows: where, J represents the moment of inertia of the motor, represents the magnetic flux generated by the permanent magnet, B represents the friction coefficient, s1 represents the first sliding mode switching surface, represents the saturation function corresponding to the first sliding mode switching, and φ represents the boundary layer thickness of the sliding mode variable structure control. k = 1 / φ; x1 = ω * -ω e ,ω * represents the reference angular velocity of the permanent magnet synchronous motor, ω e represents the electrical angular velocity of the rotor of the permanent magnet synchronous motor, and ω e = pω m ,ω m represents the mechanical angular velocity of the rotor of the permanent magnet synchronous motor, p n represents the number of pole pairs of the permanent magnet synchronous motor; c = [c1, c2, … c n-1 , 1] T , c1, c2 … c n-1 needs to satisfy p n-1 + c n-1 p n-2 + … + c2p + c1 is a Hurwitz polynomial, p is the Laplace operator; ω represents the mechanical speed of the motor.

4. The permanent magnet synchronous motor control method with adaptive adjustment of boundary layer thickness according to claim 1, characterized in that: The establishment of the mathematical function of the sliding mode switching surface according to the control variables of the permanent magnet synchronous motor includes: Establish a mathematical function of the error variable for the position control of the permanent magnet synchronous motor based on the reference given motor rotor position signal and the actual motor rotor position signal of the permanent magnet synchronous motor; Derive the mathematical function of the error variable for the position control of the permanent magnet synchronous motor, and establish a mathematical function of the second sliding mode switching surface in combination with the error variable for the position control of the permanent magnet synchronous motor.

5. The control method of the permanent magnet synchronous motor with adaptive adjustment of boundary layer thickness according to claim 4, characterized in that: Derive the mathematical function of the second sliding mode switching surface, and based on the derived mathematical function of the second sliding mode switching surface, establish a sliding mode variable structure position control law in combination with the second sliding mode switching surface and the non-linear boundary layer represented by the saturation function, where the expression of the sliding mode variable structure position control law is as follows: where J represents the moment of inertia of the motor, represents the magnetic flux generated by the permanent magnet, B represents the friction coefficient, s2 represents the first sliding mode switching surface, represents the saturation function corresponding to the second sliding mode switching surface, φ represents the boundary layer thickness of the sliding mode variable structure control, k = 1 / φ; x1 = ω * -ω e , ω * represents the reference angular velocity of the permanent magnet synchronous motor, ω e represents the electrical angular velocity of the rotor of the permanent magnet synchronous motor, and ω e = pω m , ω m represents the mechanical angular velocity of the rotor of the permanent magnet synchronous motor, p n represents the number of pole pairs of the permanent magnet synchronous motor; c = [c1, c2, … c n-1 ,1] T , c1, c2 … c n-1 need to satisfy that p n-1 + c n-1 p n-2 + … + c2p + c1 is a Hurwitz polynomial, p is the Laplace operator; represents the derivative obtained by differentiating the mathematical function of the position error variable of the permanent magnet synchronous motor system, represents the first derivative of the actual rotor position feedback of the permanent magnet synchronous motor; represents the second derivative of the reference given command position of the permanent magnet synchronous motor.

6. The control method of a permanent magnet synchronous motor with adaptive adjustment of boundary layer thickness according to any one of claims 1 to 5, characterized in that: The expression of the boundary layer thickness of the sliding mode variable structure control is as follows: φ=nφ1+(1-n)φ2 (10) where \(n = n_0 + d\) n , \(n_0 = 0.5\), the coefficient \(d\) n is obtained by taking the sliding mode switching surface as the control variable input of the fuzzy control algorithm into the fuzzy control algorithm, \(-0.5 \leq d\) n \(\leq 0.5\) and \(0 \leq n \leq 1\); \(\varphi_1\) and \(\varphi_2\) represent two different boundary layer thickness values set according to the permanent magnet synchronous motor system, satisfying \(0 \lt \varphi_1 \lt \varphi_2\); When the coefficient n is close to 1, the boundary layer thickness is closer to φ1; when n is close to 0, the boundary layer thickness is closer to φ2.

7. The control method of the permanent magnet synchronous motor with adaptive adjustment of boundary layer thickness according to claim 6, characterized in that: Coefficient d n Obtained by using the sliding mode switching surface as the input variable of the fuzzy control algorithm and inputting it into the fuzzy control algorithm, including: Take the absolute value of the distance from the state point in the system state space to the sliding mode switching surface as the input variable of the fuzzy control algorithm; Or take the absolute value of the distance from the state point in the system state space to the sliding mode switching surface and the absolute value of the speed of the state point in the system state space to the sliding mode switching surface as the input variables of the fuzzy control algorithm; Or take the absolute value of the distance from the state point in the system state space to the sliding mode switching surface, the absolute value of the speed of the state point in the system state space to the sliding mode switching surface, and the absolute value of the acceleration of the state point in the system state space to the sliding mode switching surface as the input variables of the fuzzy control algorithm; Thus, the fuzzy control algorithm adjusts the coefficient d according to the real-time state of the controlled system n to achieve adaptive fuzzy adjustment of the boundary layer thickness of the sliding mode variable structure control.

8. The control method of the permanent magnet synchronous motor with adaptive adjustment of the boundary layer thickness according to claim 7, characterized in that: The fuzzy control algorithm includes a one-dimensional fuzzy control algorithm, a two-dimensional fuzzy control algorithm, and a three-dimensional fuzzy control algorithm; select the corresponding fuzzy control algorithm according to the number of input variables of the fuzzy control algorithm.

9. The permanent magnet synchronous motor control method with adaptive adjustment of boundary layer thickness according to claim 7, characterized in that: Adaptive fuzzy adjustment is performed on the boundary layer thickness of the sliding mode variable structure control, and the satisfied conditions are as follows: When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface is greater than the threshold φ2, the fuzzy control algorithm increases the boundary layer thickness of the sliding mode variable structure control to make the state point approach the sliding mode switching surface; When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface is less than φ2 and greater than φ1, the state point is in the intermediate region at this time, and the fuzzy control algorithm reduces the boundary layer thickness of the sliding mode variable structure control; When the absolute value of the distance from the state point in the system state space to the sliding mode switching surface is less than φ1, the state point has three states: moving on the sliding mode switching surface S = 0, moving in the left region of the sliding mode switching surface, and moving in the right region of the sliding mode switching surface.

10. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein When the processor executes the computer program, it implements the permanent magnet synchronous motor control method for adaptive adjustment of the boundary layer thickness as described in any one of claims 1 to 9.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the described computer program is executed by the processor, it implements the permanent magnet synchronous motor control method for adaptive adjustment of the boundary layer thickness as described in any one of claims 1 to 9.

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