A model-free predictive speed control method and system based on permanent magnet synchronous motor

Abstract

The present invention discloses a model-free predictive speed control method and system based on a permanent magnet synchronous motor, which is applied to the field of permanent magnet synchronous motor speed control. The method comprises: establishing a pole polynomial of periodic disturbance of the permanent magnet synchronous motor; designing a model-free predictive speed controller according to the pole polynomial; outputting a current inner loop reference current according to the model-free predictive speed controller; and embedding the pole polynomial of periodic disturbance into the model-free predictive speed controller, based on the internal model principle, suppressing the periodic disturbance existing in the system, thereby improving the stability of the output speed and torque of the control system.

Description

Technical Field

[0001] The present invention relates to the field of permanent magnet synchronous motor speed control, and in particular to a model-free prediction speed control method and system based on a permanent magnet synchronous motor. Background Art

[0002] In the control system of permanent magnet synchronous motor, the cascade structure is the most common control structure. As the outer loop of the cascade structure, the speed loop not only needs to provide reference current for the current inner loop, but also needs to quickly respond to changes in external load and reference speed, which puts strict requirements on the stability and robustness of the speed outer loop. Model-free predictive speed control integrates the advantages of fast response speed and strong parameter robustness, and can improve the control performance of the speed loop. However, due to the existence of periodic and non-periodic disturbances in the control system, these disturbances usually affect the output torque of the system in the form of load fluctuations and current harmonics, thereby affecting the smooth operation of the control system. Therefore, in the speed outer loop, it is necessary to suppress the periodic and non-periodic disturbances in the system to ensure the stability of the speed and output torque of the permanent magnet synchronous motor. Compared with non-periodic disturbances, the suppression of periodic disturbances is more difficult. Due to the bandwidth limitation of the observer, high-frequency periodic disturbances cannot be effectively observed and compensated. Therefore, in order to suppress the periodic and non-periodic disturbances in the velocity loop, the present invention starts from the internal model principle and utilizes the pole polynomial of the periodic disturbance to achieve the suppression of the periodic disturbance. Summary of the invention

[0003] The purpose of this application is to provide a model-free predictive speed control method and system based on a permanent magnet synchronous motor, aiming to solve the above-mentioned problems.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] The present application provides a model-free predictive speed control method based on a permanent magnet synchronous motor, comprising:

[0006] Establish the pole polynomial of the periodic disturbance of permanent magnet synchronous motor;

[0007] designing a model-free predictive speed controller based on the pole polynomial;

[0008] The model-free predictive speed controller outputs a current inner loop reference current.

[0009] Furthermore, the motion balance equation of the permanent magnet synchronous motor is expressed as:

[0010]

[0011] Wherein, J is the moment of inertia of the permanent magnet synchronous motor; B is the friction coefficient of the permanent magnet synchronous motor; T L is the external torque of the permanent magnet synchronous motor control system; T e is the electromagnetic torque of the permanent magnet synchronous motor;

[0012] If the permanent magnet synchronous motor is surface mounted, that is, L d =L q , T e The electromagnetic torque equation is expressed as:

[0013]

[0014] Among them, n p is the number of pole pairs of the permanent magnet synchronous motor; i q is the stator current of the permanent magnet synchronous motor q axis, ψ f is the nominal flux linkage of the permanent magnet synchronous motor.

[0015] Furthermore, the step of establishing the pole polynomial of the periodic disturbance of the permanent magnet synchronous motor includes the following steps:

[0016] For a periodic signal with a period of T, when the sampling interval is Δt, the number of sampling points in one period T is N = T / Δt;

[0017] The discrete signal sampling sequence is x(n), n=0, ..., N-1. Using the inverse discrete Fourier transform, the discrete sampling signal can be reconstructed as:

[0018]

[0019] in, is the discrete Fourier series coefficient;

[0020] In the z domain, the discrete signal sampling sequence x(n) is z-transformed to obtain the z domain signal X m (z) is:

[0021]

[0022] Substituting formula (3) into formula (4) for simplification, the periodic signal is simplified by z-transformation to:

[0023]

[0024] Among them, ω = 2π / N is the fundamental frequency of the periodic signal, W l (z) represents the l-th frequency sampling filter;

[0025] Where W l (z) is expressed as:

[0026]

[0027] In formula (6), complex number operations are performed, and the real part is represented by Re and the imaginary part is represented by Im.

[0028] Furthermore, the z-domain signal X m (z) is:

[0029]

[0030] in, and is a l-th order frequency sampling filter, which can be expressed as:

[0031]

[0032]

[0033] Based on formula (7) to formula (9), X m (z) is simplified, the pole polynomial of the periodic signal is:

[0034]

[0035] Among them, l i The values ​​are 1, 2, ..., k, l i , representing higher harmonics.

[0036] Furthermore, the step of designing a model-free predictive speed controller according to the pole polynomial includes the following steps:

[0037] when Formula (1) can be rewritten according to the hyperlocal model as follows:

[0038]

[0039] In the formula (1), when calculating the relationship between speed and current, the q-axis current i output by the current inner loop is q The q-axis reference current output by the speed outer loop The relationship is:

[0040]

[0041] in, is the reference current output by the speed outer loop controller; T oi is the time constant of the equivalent first-order inertia link;

[0042] Define the matrix x m =[i q ω m], combined with formula (11) and formula (12), it is converted into a matrix form and discretized;

[0043] Then the discretized model-free predictive speed controller is:

[0044] x m (k+1)=A m x m (k)+B m u m (k)+Θ m F n (k) (13),

[0045] y m (k) = C m x m (k) (14),

[0046] where x m (k)=[i q (k) ω m (k)], is the current and speed value of the (k)th sampling period; x m (k+1)=[i q (k+1)ω m (k+1)], which are the current and speed values ​​of the (k+1)th sampling period; is the reference current value of the (k)th sampling period; y m (k) = ω m (k) is the mechanical angular velocity value of the (k)th sampling period; A m , B m , Θ m and C m are the corresponding coefficient matrices respectively.

[0047] Furthermore, in the control system of the permanent magnet synchronous motor, the pole polynomial of the first-order periodic disturbance is selected through periodic disturbance, that is:

[0048] D(z)=(1-z -1 )(1-2cos(w)z -1 +z -2 )

[0049] =1+d1z -1 +d2z -2 +d3z -3 (15)

[0050] Where, d1 = -1-2 cos(ω); d2 = 1+2 cos(ω); d3 = -1; z -1 is a shift operator, which means a delay of one control cycle.

[0051] Further, the pole polynomial is embedded into the model-free predictive speed controller, which includes the following steps:

[0052] Define Q(z -1 ) corresponds to D(z):

[0053] x s (k+1)=A m x s (k)+B m u s (k)+Θ m F s (k) (16),

[0054] Among them, x s (k+1)=Q(z -1 )x m (k+1); x s (k) = Q(z -1 )x m (k);u s (k) = Q(z -1 ) m (k); F s (k) = Q(z -1 )F n (k);

[0055] Q(z -1 ) is substituted into the discrete model-free predictive speed controller to obtain:

[0056] Q(z -1 )y m (k+1)=C m x s (k+1)

[0057] =C m A m x s (k)+C m B m u s (k)+C m Q m F s (k) (17),

[0058] Substituting the pole polynomial of the periodic disturbance into formula (17), formula (17) can be simplified as follows:

[0059] y m (k+1)=-d1y m (k)-d2y m (k-1)-d3y m (k-2)+Cm A m x s (k)+C m B m u s (k)+C m Q m F s (k)(18).

[0060] Furthermore, the model-free predictive speed controller is redesigned to define a vector group x(k)=[x s (k) T y m (k) y m (k-1) y m (k-2)] T , y(k)=y m (k) namely:

[0061]

[0062] in, C = [0 1 0 0];

[0063] The state equation of the redesigned model-free predictive speed controller is calculated as:

[0064] det(IA)=det(IA m )det(IA Q ) (20),

[0065] in, The roots of equation (20) contain the pole polynomial D(z) of the periodic perturbation.

[0066] Furthermore, the step of outputting a current inner loop reference current according to the model-free prediction speed controller comprises the following steps:

[0067] The reference speed Replace ω in formula (13) m (k+1), and substitute formula (13) into formula (19) to obtain the controller input u s (k) Perform the reverse solution; s Substituting (k) into formula (16) we can get u m (k) is inversely solved to obtain:

[0068]

[0069] Simplifying formula (21), the inner loop reference current output by the model-free predictive speed controller is calculated as:

[0070]

[0071] A model-free predictive speed control system based on a permanent magnet synchronous motor is also provided, and the specific contents include:

[0072] Establishing module: Establishing the pole polynomial of the periodic disturbance of the permanent magnet synchronous motor;

[0073] Control module: designing a model-free predictive speed controller according to the pole polynomial;

[0074] Output result module: predict the inner loop reference current of the speed controller output current according to the model-free prediction.

[0075] The present application provides a model-free predictive speed control method and system based on a permanent magnet synchronous motor, which has the following beneficial effects:

[0076] The present invention proposes a novel strategy for suppressing periodic torque fluctuations in a speed loop. Based on the internal model principle, a polynomial of periodic disturbances is included in the denominator of the transfer function of the speed loop controller, thereby suppressing periodic torque fluctuations. By embedding the periodic disturbance polynomial into a model-free predictive speed control strategy, while ensuring the dynamic response speed and parameter robustness of the speed loop, the periodic and non-periodic disturbances in the speed loop are suppressed, thereby stabilizing the speed and output torque of the control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 A schematic flow chart of a model-free predictive speed control method based on a permanent magnet synchronous motor according to an embodiment of the present application;

[0078] Figure 2 This is a structural schematic diagram of a model-free predictive speed control system based on a permanent magnet synchronous motor according to an embodiment of the present application;

[0079] Figure 3 A block diagram of a model-free predictive speed control system for a permanent magnet synchronous motor according to an embodiment of the present application;

[0080] Figure 4 The speed response and Fourier harmonic analysis of the speed of the PI under periodic disturbance according to an embodiment of the present application;

[0081] Figure 5 The speed response and Fourier harmonic analysis of the speed of the MFPSC under periodic disturbance according to an embodiment of the present application;

[0082] Figure 6 The speed response and Fourier harmonic analysis of the speed of the MFPSC-FSF under periodic disturbance according to an embodiment of the present application are shown. DETAILED DESCRIPTION

[0083] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0084] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0085] Example 1

[0086] Reference Figure 1 , which is a flow chart of a model-free predictive speed control method based on a permanent magnet synchronous motor proposed in this application;

[0087] The present application provides a model-free predictive speed control method based on a permanent magnet synchronous motor, and the specific contents include:

[0088] Establish the pole polynomial of the periodic disturbance of permanent magnet synchronous motor.

[0089] In this embodiment, the motion balance equation of the permanent magnet synchronous motor is expressed as:

[0090]

[0091] Wherein, J is the moment of inertia of the permanent magnet synchronous motor; B is the friction coefficient of the permanent magnet synchronous motor; T L is the external torque of the permanent magnet synchronous motor control system; T e is the electromagnetic torque of the permanent magnet synchronous motor;

[0092] If the permanent magnet synchronous motor is surface mounted, that is, L d =L q , T e The electromagnetic torque equation is expressed as:

[0093]

[0094] Among them, n p is the number of pole pairs of the permanent magnet synchronous motor; i q is the stator current of the permanent magnet synchronous motor q axis, ψ f is the nominal flux linkage of the permanent magnet synchronous motor.

[0095] For a periodic signal with a period of T, when the sampling interval is Δt, the number of sampling points in one period T is N = T / Δt;

[0096] At this time, the discrete signal sampling sequence is x(n), n=0, ..., N-1. Using the inverse discrete Fourier transform, the discrete sampling signal can be reconstructed as:

[0097]

[0098] in, is the discrete Fourier series coefficient;

[0099] In the z domain, the discrete signal sampling sequence x(n) is z-transformed to obtain the z domain signal X m (z) is:

[0100]

[0101] Substituting formula (3) into formula (4) for simplification, the periodic signal is simplified by z-transformation to:

[0102]

[0103] Among them, ω = 2π / N is the fundamental frequency of the periodic signal, W l (z) represents the l-th frequency sampling filter;

[0104] Where W l (z) is expressed as:

[0105]

[0106] In formula (6), complex number operations are performed, and the real part is represented by Re and the imaginary part is represented by Im.

[0107] The z-domain signal X m (z) is:

[0108]

[0109] in, and is a l-th order frequency sampling filter, which can be expressed as:

[0110]

[0111]

[0112] Based on formula (7) to formula (9), X m (z) is simplified, the pole polynomial of the periodic signal is:

[0113]

[0114] Among them, l i The values ​​are 1, 2, ..., k, li , representing higher harmonics.

[0115] A model-free predictive speed controller is designed based on the pole polynomial.

[0116] In this embodiment, when Formula (1) can be rewritten according to the hyperlocal model as follows:

[0117]

[0118] In the cascade structure, the sampling period of the outer speed loop is larger than the sampling period of the inner current loop. Therefore, in formula (1), when calculating the relationship between speed and current, the q-axis current i is used. q It comes from the current inner loop. When it participates in the calculation of the speed outer loop, it will cause deviation due to the different sampling periods. At this time, the q-axis current i output by the current inner loop q The q-axis reference current output by the speed outer loop The relationship is:

[0119]

[0120] in, is the reference current output by the speed outer loop controller; T oi is the time constant of the equivalent first-order inertia link, which can be designed according to the zero-pole distribution of the current inner loop closed-loop system;

[0121] Define the matrix x m =[i q ω m ], combined with formula (11) and formula (12), it is converted into a matrix form and discretized;

[0122] Then the discretized model-free predictive speed controller is:

[0123] x m (k+1)=A m x m (k)+B m u m (k)+Θ m F m (k) (13),

[0124] y m (k) = C m x m (k) (14),

[0125] where x m (k)=[i q (k) ω m (k)], is the current and speed value of the (k)th sampling period; xm (k+1)=[i q (k+1)ω m (k+1)], which are the current and speed values ​​of the (k+1)th sampling period; is the reference current value of the (k)th sampling period; y m (k) = ω m (k), is the mechanical angular velocity value of the (k)th sampling period; A m , B m , Θ m and C m are the corresponding coefficient matrices respectively.

[0126] In the permanent magnet synchronous motor control system, taking into account the periodic disturbance and the computational burden, the first-order periodic disturbance pole polynomial is usually selected, which is:

[0127] D(z)=(1-z -1 )(1-2cos(w)z -1 +z -2 )

[0128] =1+d1z -1 +d2z -2 +d3z -3 (15)

[0129] Where, d1 = -1-2 cos(ω); d2 = 1+2 cos(ω); d3 = -1; z -1 is a shift operator, which means a delay of one control cycle.

[0130] The pole polynomial of periodic disturbance is embedded into the model-free speed prediction controller as follows:

[0131] x s (k+1)=A m x s (k)+B m u s (k)+Θ m F s (k) (16),

[0132] Among them, x s (k+1)=Q(z -1 )x m (k+1); x s (k) = Q(z -1 )x m (k);u s (k) = Q(z -1 ) m (k); F s (k) = Q(z -1)F n (k);

[0133] Similarly, Q(z- 1 ) is substituted into the discrete model-free predictive speed controller to obtain:

[0134] Q(z -1 )y m (k+1)=C m x s (k+1)

[0135] =C m A m x s (k)+C m B m u s (k)+C m Q m F s (k) (17),

[0136] Substituting the pole polynomial of the periodic disturbance into formula (17), formula (17) can be simplified as follows:

[0137] y m (k+1)=-d1y m (k)-d2y m (k-1)-d3y m (k-2)+C m A m x s (k)+C m B m u s (k)+C m Q m F s (k)(18).

[0138] The model-free predictive speed controller is redesigned to define the vector set x(k)=[x s (k) T y m (k) y m (k-1) y m (k-2)] T , y(k)=y m (k) namely:

[0139]

[0140] in, C = [0 1 0 0];

[0141] The state equation of the redesigned model-free predictive speed controller is calculated as:

[0142] det(IA)=det(IA m )det(IA Q ) (20),

[0143] in, The roots of equation (20) contain the pole polynomial D(z) of the periodic perturbation.

[0144] The model-free predictive speed controller outputs a current inner loop reference current.

[0145] In this embodiment, in order to obtain the q-axis reference current required by the current inner loop, the reference speed Replace ω in formula (13) m (k+1), and substitute formula (13) into formula (19) to obtain the controller input u s (k) Perform the reverse solution; s Substituting (k) into formula (16) we can get u m (k) is inversely solved to obtain:

[0146]

[0147] Simplifying formula (21), the inner loop reference current output by the model-free predictive speed controller is calculated as:

[0148]

[0149] In summary, this application takes advantage of the fast response speed of predictive control and designs a predictive speed control strategy based on a hyperlocal model; while ensuring the response speed of the speed loop controller, the use of the hyperlocal model can not only improve the robustness of the controller when the parameters are mismatched, but also use the observer in the hyperlocal model to observe and compensate for the non-periodic disturbances and external loads in the speed loop. At the same time, by embedding the pole polynomial of the periodic disturbance into the model-free predictive speed controller, starting from the internal model principle, the periodic disturbances in the system are suppressed, thereby improving the stability of the output speed and torque of the control system.

[0150] Example 2

[0151] Reference Figure 2 , which is a structural schematic diagram of a model-free predictive speed control system based on a permanent magnet synchronous motor proposed in this application;

[0152] The present application provides a model-free predictive speed control system based on a permanent magnet synchronous motor, and the specific contents include:

[0153] Establishing module 100: establishing a pole polynomial of a periodic disturbance of a permanent magnet synchronous motor;

[0154] Control module 200: designing a model-free predictive speed controller according to the pole polynomial;

[0155] Output result module 300: outputs a current inner loop reference current according to the model-free prediction speed controller.

[0156] Reference Figure 3 , is a block diagram of a model-free predictive speed control system for a permanent magnet synchronous motor of an embodiment of the present application; the control system mainly includes a speed outer loop and a current inner loop; the main purpose of the speed loop is to track the reference speed and output the q-axis reference current for the current inner loop. In order to verify the effectiveness of the speed loop control algorithm proposed in the present invention, the controllers of the current inner loop all use a finite control set model-free predictive current controller to track the reference current; the speed outer loop uses proportional integral control (PI), model-free predictive speed control (MFPSC) and model-free predictive speed control with embedded perturbation pole polynomial (MFPSC-FSF) for comparison. In order to more clearly compare the effects of different algorithms, periodic disturbances are actively added to the control system to verify the control strategy proposed in the present invention.

[0157] Reference Figure 4 , which is the speed response of PI under periodic disturbance and Fourier harmonic analysis of speed in one embodiment of the present application; when there is a periodic disturbance in the system, after a series of links, the periodic disturbance will affect the smooth operation of the output speed, which will be displayed as periodic fluctuations in the speed.

[0158] Reference Figure 5 This is a speed response and Fourier harmonic analysis of the speed of the MFPSC under periodic disturbance of an embodiment of the present application; compared with PI, since there is an observer in the MFPSC, some disturbances in the system can be observed, so the MFPSC has a better speed tracking effect.

[0159] Compared with PI control, the total harmonic distortion of MFPSC is reduced from 5.51% to 0.59%; at the same time, the 2nd, 6th and 12th harmonics in the speed are reduced. However, after comparing the speeds, it can be seen that the periodic speed still exists in MFPSC, which also means that the periodic disturbance in the control system still affects the normal operation of the system. At this time, there are still obvious 2nd, 6th and 12th harmonics in the output speed.

[0160] Reference Figure 6The speed response and Fourier harmonic analysis of the speed of the MFPSC-FSF under periodic disturbance of an embodiment of the present application are performed; according to the internal model principle, when the control system includes a disturbance polynomial, the system can effectively track the reference signal under the action of the disturbance; therefore, by embedding the pole polynomial of the periodic disturbance into the MFPSC, the periodic disturbance existing in the control system can be effectively suppressed.

[0161] Compared with the attached Figure 4 and attached Figure 5 , attached Figure 6 No obvious periodic fluctuations can be seen in the output torque. At this time, the periodic disturbance in the current has been effectively suppressed and cannot affect the output torque, thus showing a more stable speed. At the same time, it can be seen from the Fourier analysis of the speed that the total harmonic distortion of the speed output by the permanent magnet synchronous motor is reduced from 0.59% to 0.1%; the 2nd, 6th and 12th harmonics in the system are also effectively suppressed.

[0162] In summary, through comparative analysis of simulation experimental results, it can be seen that the new speed loop controller proposed in the present invention, which embeds the periodic disturbance polynomial into the model-free predictive speed control, can improve the speed stability of the control system; by including the disturbance polynomial in the transfer function of the speed loop controller, the periodic disturbance existing in the control system can be effectively suppressed, thereby improving the stability of the output speed of the control system.

[0163] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0164] The above description is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

[0165] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

[0166] Of course, the present invention may have many other implementations. Based on this implementation, other implementations obtained by ordinary technicians in this field without any creative work are all within the scope of protection of the present invention.

Claims

1. A model-free predictive speed control method based on a permanent magnet synchronous motor, characterized in that: include: Establish the pole polynomial of the periodic disturbance of permanent magnet synchronous motor; designing a model-free predictive speed controller based on the pole polynomial; Outputting a current inner loop reference current of the speed controller according to the model-free prediction; In the control system of the permanent magnet synchronous motor, the pole polynomial of the first-order periodic disturbance is selected through periodic disturbance, that is: D(z)=(1-z -1 )(1-2cos(in)z -1 +from -2 ) =1+d1z -1 +d2z -2 +d3z -3 (15), Where, d1 = -1-2cos(w); d2 = 1+2cos(w); d3 = -1; z -1 is a shift operator, i.e., delaying one control cycle; The pole polynomial is embedded into the model-free predictive speed controller, which includes the following steps: Define Q(z -1 ) corresponds to D(z): x s (k+1)=A m x s (k)+B m u s (k)+Θ m F s (k) (16), where x s (k + 1) = Q(z -1 )x m (k + 1); x s (k) = Q(z -1 )x m (k); u s (k) = Q(z -1 )u m (k); F s (k) = Q(z -1 )F m (k); Q(z -1 ) is substituted into the discretized model-free predictive speed controller to obtain: Q(z -1 )y m (k+1)=C m x s (k+1)=C m FLUENT m x s (k)+C m B m u s (k)+C m Θ m F s (k)(17), Substituting the pole polynomial of the periodic disturbance into formula (17), formula (17) can be simplified as: y m (k+1)=-d1y m (k)--d2y m (k-1)-d3y m (k-2)=C m A m x s (k)+C m B m u s (k)+C m Θ m F s (k)(18), Among them, x m (k)=[i q (k)ω m (k)], is the current and speed value of the (k)th sampling period; x m (k+1)=[i q (k+1)ω m (k+1)], which are the current and speed values ​​of the (k+1)th sampling period; is the reference current value of the (k)th sampling period; y m (k) = ω m (k) is the mechanical angular velocity value of the (k)th sampling period; A m , B m , C m and θ m are the corresponding coefficient matrices respectively; The model-free predictive speed controller is redesigned to define the vector set x(k)=[x s (k) T y m (k)y m (k-1)y m (k-2)] T , y(k)=y m (k) namely: in, C = [0 1 0 0]; The state equation of the redesigned model-free predictive speed controller is calculated as: it(IA)=it(IA m )it(IA Q )(20), in, The roots of equation (20) contain the pole polynomial D(z) of the periodic perturbation.

2. A model-free predictive speed control method based on a permanent magnet synchronous motor according to claim 1, characterized in that: The motion balance equation of the permanent magnet synchronous motor is expressed as: Wherein, J is the moment of inertia of the permanent magnet synchronous motor; B is the friction coefficient of the permanent magnet synchronous motor; T L is the external torque of the permanent magnet synchronous motor control system; T e is the electromagnetic torque of the permanent magnet synchronous motor; If the permanent magnet synchronous motor is surface mounted, that is, L d =L q , T e The electromagnetic torque equation is expressed as: Among them, n p is the number of pole pairs of the permanent magnet synchronous motor; i q is the stator current of the permanent magnet synchronous motor q axis, ψ f is the nominal flux linkage of the permanent magnet synchronous motor.

3. A model-free predictive speed control method based on a permanent magnet synchronous motor according to claim 1, characterized in that: The step of establishing the pole polynomial of the periodic disturbance of the permanent magnet synchronous motor comprises the following steps: For a periodic signal with a period of T, when the sampling interval is Δt, the number of sampling points in one period T is N = T / Δt; The discrete signal sampling sequence is x(n), n=0,…,N-1. Using the inverse discrete Fourier transform, the discrete sampling signal can be reconstructed as: in, is the discrete Fourier series coefficient; In the z domain, the discrete signal sampling sequence x(n) is z-transformed to obtain the z domain signal X m (z) is: Substituting formula (3) into formula (4) for simplification, the periodic signal is simplified by z-transformation to: Among them, ω = 2π / N is the fundamental frequency of the periodic signal, W l (z) represents the l-th frequency sampling filter; Where W l (z) is expressed as: In formula (6), complex number operations are performed, and the real part is represented by Re and the imaginary part is represented by Im.

4. A model-free predictive speed control method based on a permanent magnet synchronous motor according to claim 3, characterized in that: The z-domain signal X m (z) is: in, and is a l-th order frequency sampling filter, which can be expressed as: Based on formula (7) to formula (9), X m (z) is simplified, the pole polynomial of the periodic signal is: Among them, l i The values ​​are 1, 2, ..., k, l i , representing higher harmonics.

5. The model-free predictive speed control method based on a permanent magnet synchronous motor according to claim 2, characterized in that: The step of designing a model-free predictive speed controller according to the pole polynomial comprises the following steps: when Formula (1) can be rewritten according to the hyperlocal model as follows: In the formula (1), when calculating the relationship between speed and current, the q-axis current i output by the current inner loop is q The q-axis reference current output by the speed outer loop The relationship is: in, is the reference current output by the speed outer loop controller; T oi is the time constant of the equivalent first-order inertia link; Define the matrix x m =[i q ω m ], combined with formula (11) and formula (12), it is converted into a matrix form and discretized; Then the discretized model-free predictive speed controller is: x m (k+1)=A m x m (k)+B m u m (k)+Θ m F m (k)(13), y m (k)=C m x m (k) (14), where x m (k)=[i q (k)ω m (k)], is the current and speed value of the (k)th sampling period; x m (k+1)=[i q (k+1)ω m (k+1)], which are the current and speed values ​​of the (k+1)th sampling period; is the reference current value of the (k)th sampling period; y m (k) = ω m (k), is the mechanical angular velocity value of the (k)th sampling period; A m , B m , Θ m and C m are the corresponding coefficient matrices respectively.

6. A model-free predictive speed control method based on a permanent magnet synchronous motor according to claim 1, characterized in that: The step of outputting a current inner loop reference current according to the model-free predictive speed controller comprises the following steps: The reference speed Replace the ω of the model-free predictive speed controller m (k+1), and substitute the model-free predictive speed controller into formula (19) to obtain the controller input u s (k) Perform the reverse solution; s Substituting (k) into formula (16) we can get u m (k) is inversely solved to obtain: Simplifying formula (21), the inner loop reference current output by the model-free predictive speed controller is calculated as:

7. A system for a model-free predictive speed control method based on a permanent magnet synchronous motor according to claim 1, characterized in that ,include: Establishing module: Establishing the pole polynomial of the periodic disturbance of the permanent magnet synchronous motor; A control module: designs a model-free predictive speed controller according to the pole polynomial; an output result module: outputs a current inner loop reference current according to the model-free predictive speed controller.

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