Superspiral sliding mode controller and active electromagnetic bearing control system and method

Abstract

The invention belongs to the technical field of active magnetic suspension bearings, and discloses a super-spiral sliding mode controller and an active electromagnetic bearing control system and method.The super-spiral sliding mode controller comprises a sign function device used for inputting positive and negative calculation of a sliding mode surface; the integrator is used for integrating the result of the sign function device; the first gainer is used for multiplying the result of the integrator by an integral gain coefficient; the power sign function device is used for taking a module value of the input sliding mode surface, taking an index of the module value through an index coefficient, and multiplying the index by a sign function result; the second gainer is used for inputting a result of the power sign function device and multiplying the result by an exponential gain coefficient; and the subtracter is used for obtaining the super-spiral sliding mode reaching law by taking the difference. According to the method, the superhelix reaching law can enable the system state to be smooth near the sliding mode surface, the switching gain is relatively small, and the buffeting of the system is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of active magnetic bearings, and in particular relates to a super-helical sliding mode controller, an active electromagnetic bearing control system and a method. Background Art

[0002] Active magnetic bearings (AMBs) have been widely used in high-power and high-speed rotating mechanical systems due to their advantages of no friction and no lubrication. However, how to control the AMBs rotor to stably suspend at the desired position has always been an important issue. AMBs is a typical nonlinear system, which is generally modeled by local linearization methods, and then accurately controlled by linear control or nonlinear control. PID control is generally used in engineering, but AMBs will be subject to some disturbances during operation, and changes in operating conditions will greatly reduce the robustness of PID control. Therefore, the controller itself needs to have strong robustness to overcome the internal and external disturbances of the AMBs system, thereby effectively improving its reliability.

[0003] Among the many robust control algorithms, sliding mode control (SMC) has the advantages of strong adaptability, good robustness, insensitivity to unknown parameters and disturbances, and easy implementation, and is widely used in various nonlinear systems including AMBs. However, simple sliding mode control uses a linear sliding mode function, and the system error can usually only converge slowly asymptotically.

[0004] The Chinese patent publication number is CN118157526A, and the name is a patent application for a permanent magnet synchronous motor control method based on an improved linear superhelix. By establishing a two-phase stationary coordinate system, the stator current equation is obtained, the mechanical motion equation of the permanent magnet synchronous motor is established, the state variables of the permanent magnet synchronous motor system are defined, the integral sliding mode surface is established, and a reaching law speed controller is constructed. An improved linear superhelix sliding film observer is established to estimate the back electromotive force and calculate the rotor speed and rotor position of the permanent magnet synchronous motor. This method is improved on the basis of the linear superhelix sliding mode observer. When the system error increases, the sliding mode gain can be adjusted with the system error, and the motor speed can be accurately estimated without using a low-pass filter, thereby improving its anti-interference ability. However, this patent application cannot achieve rapid convergence of the system error and cannot solve the problem of slow response speed. Summary of the invention

[0005] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a super-helical sliding mode controller, an active electromagnetic bearing control system and a method. Through the super-helical sliding mode controller of the present invention, the super-helical convergence law can make the system state smooth near the sliding mode surface and the switching gain small, thereby reducing system jitter.

[0006] To achieve the above object, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a super spiral sliding mode controller, comprising: Sign function, used for the positive and negative calculation of the input sliding surface s; an integrator, the integrator being used to integrate the result of the symbolic function generator; A first gain device is used to multiply the result of the integrator by an integral gain coefficient. k 3; A power sign function, the power sign function is used to input the sliding surface s The modulus value is taken and the modulus value is passed through the exponential coefficient c Taking the exponent of it gives , and multiply it with the sign function result sign(s) to get ; A second gainer, the second gainer is used to input the result of the power sign function and multiply it by the exponential gain coefficient k 4; Subtractor, used for and Taking the difference, we get the super-helical sliding mode reaching law .

[0007] Optionally, the control quantity of the super-helical sliding mode controller is i c The calculation formula is:

[0008] b 0 =k s / m in: M Aggregate interference d The upper bound of , b 0 is the displacement gain, k s is the displacement stiffness coefficient, i eq is the control quantity of the equivalent controller; i sw is the control quantity of the switching controller of the rotor system.

[0009] Optionally, the control quantity of the equivalent controller is ieq The calculation formula is:

[0010] Where: k 1>0, k 2>0,1< b <2, a > b , a 0 is the displacement gain, a 0= k i / m , m is the rotor mass, k i is the current stiffness coefficient; e 1 is the deviation between the displacement reference value and the rotor displacement value; e 2 Yes e The derivative of 1.

[0011] Optionally, the switching controller of the rotor system controls the amount i sw The calculation formula is:

[0012] Where: k 3>0, k 4>0,0< c <1, k 3 and k 4 is the gain coefficient, c is the exponential coefficient, s is the sliding surface and also the system state.

[0013] Optionally, the formula of the sign function sign(s) is: When s<0, sign(s)= 1; When s<0, sign(s)= 0; When s<0, sign(s)= -1.

[0014] Optionally, the reaching law of the super-helical sliding mode controller is:

[0015] Where: k 3>0, k 4>0,0< c <1, s is the sliding surface and also the system state.

[0016] Optionally, the control quantity of the super-helical sliding mode controller is i c The calculation formula is:

[0017] Where: , d is the aggregate interference, M Aggregate interference d The upper bound of , that is, the maximum value of the perturbation, b 0 is the displacement gain, b 0 =k s / m , k s is the displacement stiffness coefficient, m is the rotor mass, a 0 is the displacement gain, a 0= k i / m , k i is the current stiffness coefficient, k 1>0, k 2>0, k 3>0, k 4>0, s is the sliding surface, and also the system state, y 1 is the rotor displacement value, x 2 for x The differential of 1, y r is the displacement reference value, e 2 Yes e The derivative of 1, e 1 is the deviation between the displacement reference value and the rotor displacement value; a >0, 1< b <2.

[0018] In a second aspect, the present invention provides an active electromagnetic bearing control system, comprising a super helical sliding mode controller and an active electromagnetic bearing, wherein the active electromagnetic bearing is used to input a control quantity of the super helical sliding mode controller. i c With aggregate interference d , resulting in rotor displacement y 1.

[0019] Optionally, the following steps are included: Enter displacement reference value y r , rotor displacement y 1 to the super helical sliding mode controller, calculate the control quantity of the super helical sliding mode controller i c ; The amount of control ic With aggregate interference d To the input to the active electromagnetic bearing, generating rotor displacement y 1; The sliding surface s Perform positive and negative calculations to obtain sign(s) ,right sign(s) Integrate and multiply by the gain factor k 3. Get ; The sliding surface s First take the modulus value through the exponential coefficient c Taking the exponent of it gives , multiplied by the sign function result sign(s) , integrate the result, and then multiply it by the gain factor k 4. Get ; Will and Taking the difference, we get the super-helical sliding mode reaching law s= .

[0020] Optionally, after obtaining the super-helical sliding mode reaching law s, the super-helical sliding mode reaching law s is input as a sliding mode surface into a symbolic function device for cyclic calculation.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention can make the superhelical reaching law make the system state smooth near the sliding mode surface and the switching gain small, thereby reducing system chattering.

[0022] The present invention uses adaptive non-singular fast terminal sliding mode control as the control algorithm to address the two problems of slow response speed and weak anti-interference ability in the active magnetic bearing rotor position control. The switching gain of the traditional reaching law is a constant, and the magnitude of the system jitter is related to the magnitude of the switching gain. The present invention changes the switching gain into a power function related to the system state through the super-twist reaching law, and also uses an integral function to process the switching function.

[0023] Furthermore, the present invention combines the non-singular fast terminal sliding mode function with the improved superhelical reaching law and adopts the SNFTSMC (Nonsingular Fast Terminal Sliding Mode Control) control algorithm, which can effectively solve the contradiction between superhelical sliding mode control in suppressing chattering and disturbance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are for explanation purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 It is the working principle diagram of the single-degree-of-freedom AMBs system; Figure 2 It is a non-singular fast terminal sliding mode function structure diagram; Figure 3 is the schematic diagram of the super-helical sliding mode controller; Figure 4 is the phase trajectory of the AMBs system; Figure 5 It is the overall control structure diagram of the AMBs system; Figure 6 yes f 0=50 Hz When the rotor speed n0=3000r / min, SNFTSMC rotor floating displacement waveform; Figure 7 yes; f 0=50 Hz When the rotor speed n0=3000r / min, the floating displacement waveform of the traditional SMC rotor; Figure 8 yes; f 0=100 Hz When the rotor speed n0=6000r / min, SNFTSMC rotor floating displacement waveform; Fig. 9 yes f 0=100 Hz When the rotor speed n0=6000r / min, the floating displacement waveform of the traditional SMC rotor; Fig.10 yes f 0=150 Hz When the rotor speed n0=9000r / min, SNFTSMC rotor floating displacement waveform; Fig.11 yes f 0=150 Hz When the rotor speed n0=9000r / min, the floating displacement waveform of the traditional SMC rotor; Fig.12 yes f 0=200 Hz When the rotor speed n0=12000r / min, SNFTSMC rotor floating displacement waveform; Fig.13 yes f0=200 Hz When the rotor speed n0=12000r / min, the floating displacement waveform of the traditional SMC rotor. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0026] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0028] When an element is referred to as being "disposed on" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may also be a central element. The terms "vertical", "horizontal", "left", "right" and similar expressions used in the present invention are for illustrative purposes only and are not intended to be the only embodiment. If the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but it can be slightly tilted.

[0029] It should be noted that similar reference numerals and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further defined and explained in the subsequent figures. In the description of the present invention, it is to be understood that the terms "include" and "comprise" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.

[0030] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the present invention in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0031] The present invention is described in detail below with reference to the accompanying drawings.

[0032] A control system for an active electromagnetic bearing, comprising: Active electromagnetic bearings for input control i c With aggregate interference d , resulting in rotor displacement y 1; where the rotor displacement y 1 Obtained through measurement.

[0033] A super-helical sliding mode controller is used to input a displacement reference value. y r , rotor displacement y 1. Calculate the control quantity i c .

[0034] The super spiral sliding mode controller comprises: Sign function, used for the positive and negative calculation of the input sliding surface s; Integrator, the integrator is used to s )integral; A first gain device is used to multiply the result of the integrator by an integral gain coefficient. k 3; A power sign function, the power sign function is used to input the sliding surface s The modulus value is taken and the modulus value is passed through the exponential coefficient c Taking the exponent of it gives , and multiply it with the sign function result sign(s) to get ; A second gainer, the second gainer is used to input the result of the power sign function and multiply it by the exponential gain coefficient k 4; Subtractor, used for and Taking the difference, we get the super-helical sliding mode reaching law .

[0035] Example 1 Figure 1 This is the working principle diagram of the single-degree-of-freedom AMBs system. The single-degree-of-freedom AMBs system obtains the actual displacement of the rotor through the sensor. y , the actual displacement y With expected position y r Error e 1 is input into the controller, the controller performs calculations to obtain the control signal, and then differentiates it from the bias signal, and finally transmits the differential signal to the power amplifier to generate the corresponding current, which is sent to the electromagnet coil, and the electromagnet generates suction to attract the rotor to the desired position.

[0036] AMBs adopts an 8-level C-type structure. According to Maxwell's formula, the electromagnetic force exerted by the two magnetic poles on the rotor is Formula 1 Where: i is the current flowing through the coil, l is the air gap length, A is the cross-sectional area of ​​a single magnetic pole, is the vacuum permeability, α is half the angle between the magnetic poles, n is the number of coil turns.

[0037] The electromagnet controls the rotor using differential control. i 0, y 0) is taken as the reference point. When the rotor moves upward, the displacement is y When the air gap between the rotor and the upper electromagnet becomes y 0- y , then the working current input to the upper electromagnet coil is i 0- i ; The air gap between the rotor and the electromagnet below becomes y 0+ y , the working current input to the lower electromagnet coil is i 0+ i , the resultant force in the vertical direction is Formula 2 In formula 2, the displacementy , control current i As a reference point ( i 0, y 0) neighborhood, at the reference point ( i 0, y 0) f ( i , y ) performs Taylor expansion: Formula 3 Where: f R is the high-order part (also called the unmodeled part), k i , k s are the current stiffness coefficient and the displacement stiffness coefficient respectively.

[0038] k i , k s The specific expression is Formula 4 Gravity m g. Unknown disturbance f d All are taken into account in the system, then the state equation of the system is Formula 5 Where: m is the rotor mass, a 0 is the displacement gain, a 0= k i / m , k i is the current stiffness coefficient; b 0 is the displacement gain, b 0= k s / m, k s is the displacement stiffness coefficient; d is the aggregate interference, d =( f R + f d - mg ) / m .

[0039] Through the mathematical model of the magnetic suspension rotor system, the following Figure 2 The structure diagram of the non-singular fast terminal sliding mode function is shown: The specific expression of the non-singular fast terminal sliding mode function is: Formula 6 Where: k 1>0, k 2>0,1< b <2, a > b , e 1 is the deviation between the displacement reference value and the rotor displacement value, s is the sliding surface and also the system state.

[0040] The sliding surface is the sliding function s =0; Let equation 6 be 0, and we get: Formula 7 Where: sign(s) is a symbolic function.

[0041] Set error e 1From the initial value e The time taken for 1(0) to converge to 0 is t f , solve equation 7, and we get t f The solution is Formula 8 Where: F is a Gaussian geometric function.

[0042] The derivative of Equation 6 is Formula 9 Ignore the aggregate interference in Equation 5 d , Equation 9 is equal to 0, and the equivalent controller is Formula 10 In order to speed up the approach speed and reduce the chattering in the control process, the super-helical sliding mode controller adopts the super-helical approach law, and its structure is as follows: Figure 3 shown.

[0043] The specific expression of the superhelical reaching law is: Formula 11 Where: k 3>0, k 4>0,0< c <1.

[0044] Sliding mode function s Distance sliding surface s =0 is far away, Larger values, sliding mode function s Approaching the sliding surface at a higher speed s =0; sliding mode function sDistance sliding surface s =0 is small, The value is small, the sliding mode function s Approach the sliding surface at a lower speed s = 0. Switching gain of the sign function in the sliding mode function The magnitude of determines the severity of chattering. The use of the superhelical reaching law can both weaken chattering and accelerate system convergence.

[0045] Therefore, the switching controller of the AMBs rotor system is defined as Formula 12 Considering the existence of lumped disturbance in the system, the overall controller is Formula 13 Where: M Aggregate interference d The upper bound of .

[0046] In order to prove the stability of the SNFTSMC controller, the Lyapunov function is constructed as Formula 14 Formula 15 when e 2 At 0 o'clock, it is known k 2. k 3. k 4. b are greater than 0, and ≤ M , then we have: Formula 16 At this time, the sliding mode function s Will reach the sliding surface in a limited time s =0.

[0047] when e When 2=0, now combining equation 13 and equation 5, we have: Formula 17 According to Formula 17, when the sliding mode function s＞ 0 o'clock, , when the sliding mode function s <0: . Figure 5 is the system phase trajectory under the controller, with the sliding mode function s Take 2 as an example, e 2=0, hour, e 2 must be in a certain neighborhood The sliding mode functions 2 will inevitably move downward, when the sliding mode function s 2 Arrival Neighborhood hour, e 2≠0, sliding mode function s 2 will reach the sliding surface as shown in Equation 16 s =0, sliding mode function s 4Same.

[0048] Example 2 The present invention provides a control system for an active electromagnetic bearing, comprising: A super-helical sliding mode controller is used to input a displacement reference value. y r , rotor displacement y 1. Calculate the control quantity i c ; Active electromagnetic bearing system for input control quantity i c With aggregate interference d , resulting in rotor displacement y 1; The super spiral sliding mode controller comprises: Symbolic function for inputting sliding surface s Positive and negative calculations; Integrator, used to integrate sign( s ) points; The first amplifier is used to sign(s) The integral of k 4. Get ; Power sign function, used to apply power to the input sliding surface s The modulus value is taken, and the modulus value is exponentially obtained by taking the exponential coefficient c. , and then multiply it with the sign function result sign(s) to get ; The second amplifier is used to Multiply by the exponential gain factor k 3. Get ; Subtractor, used for and Taking the difference, we get the super-helical sliding mode reaching law .

[0049] Considering the existence of lumped disturbance in the system, the overall controller is .

[0050] in: MAggregate interference d The upper bound of .

[0051] Example 3 A control system of an active electromagnetic bearing of the present invention is simulated and analyzed, and Table 1 shows the specific parameters of the AMBs.

[0052] Table 1

[0053] In order to compare the superior performance of the SNFTSMC (Self-Tuning Nonsingular Fast Terminal Sliding Mode Controller) of the present invention, SMC (Sliding Mode Control) is added to the verification. Table 2 shows the parameters of each controller.

[0054] Table 2

[0055] f 0=50 Hz When the rotor speed n 0=3000r / min, the simulation results of SNFTSMC and traditional SMC rotor floating displacement data are as follows Figure 6 Figure 7 shown.

[0056] f 0=100 Hz When the rotor speed n 0=6000 r / min The simulation results of SNFTSMC and traditional SMC rotor floating displacement data are as follows: Figure 8 Fig. 9 shown.

[0057] f 0=1500 Hz When the rotor speed n 0=9000 r / min The simulation results of SNFTSMC and traditional SMC rotor floating displacement data are as follows: Fig.10 Fig.11 shown.

[0058] f 0=200 Hz When the rotor speed n 0=12000 r / min The simulation results of SNFTSMC and traditional SMC rotor floating displacement data are as follows: Fig.12 Fig.13shown.

[0059] At each frequency, compared with the traditional SMC, the SNFTSMC rotor floating displacement is smaller and reaches the target position more quickly. The simulation and experiment verify that the system of the present invention has strong robustness and low jitter performance.

[0060] Unless otherwise specified, the device elements involved in the above embodiments are all conventional device elements, and the structural settings, working modes or control modes involved are all conventional settings, working modes or control modes in the art unless otherwise specified.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A super spiral sliding mode controller, characterized in that: include: Sign function, used for the positive and negative calculation of the input sliding surface s; an integrator, the integrator being used to integrate the result of the symbolic function generator; A first gain device is used to multiply the result of the integrator by an integral gain coefficient. k 3; A power sign function, the power sign function is used to input the sliding surface s The modulus value is taken and the modulus value is passed through the exponential coefficient c Taking the exponent of it gives , and multiply it with the sign function result sign(s) to get ; A second gainer, the second gainer is used to input the result of the power sign function and multiply it by the exponential gain coefficient k 4; Subtractor, used for and Taking the difference, we get the super-helical sliding mode reaching law .

2. A super spiral sliding mode controller according to claim 1, characterized in that: The control quantity of the super helical sliding mode controller i c The calculation formula is: b 0 =k s / m in: M Aggregate interference d The upper bound of , b 0 is the displacement gain, k s is the displacement stiffness coefficient, i eq is the control quantity of the equivalent controller; i sw is the control quantity of the switching controller of the rotor system.

3. A super spiral sliding mode controller according to claim 2, characterized in that: The control quantity of the equivalent controller i eq The calculation formula is: Where: k 1>0, k 2>0,1< b <2, a > b , a 0 is the displacement gain, a 0= k i / m , m is the rotor mass, k i is the current stiffness coefficient; e 1 is the deviation between the displacement reference value and the rotor displacement value; e 2 Yes e The derivative of 1.

4. A super spiral sliding mode controller according to claim 2, characterized in that: The switching controller of the rotor system controls the i sw The calculation formula is: Where: k 3>0, k 4>0,0< c <1, k 3 and k 4 is the gain coefficient, c is the exponential coefficient, s is the sliding surface and also the system state.

5. A super spiral sliding mode controller according to claim 1, characterized in that: The formula of the sign function sign(s) is: When s<0, sign(s)= 1; When s<0, sign(s)= 0; When s<0, sign(s)= -1.

6. A super spiral sliding mode controller according to claim 1, characterized in that: The reaching law of the super-helical sliding mode controller is: Where: k 3>0, k 4>0,0< c <1, s is the sliding surface and also the system state.

7. A super spiral sliding mode controller according to claim 1, characterized in that: The control quantity of the super helical sliding mode controller i c The calculation formula is: Where: , d is the aggregate interference, M Aggregate interference d The upper bound of , that is, the maximum value of the perturbation, b 0 is the displacement gain, b 0 =k s / m , k s is the displacement stiffness coefficient, m is the rotor mass, a 0 is the displacement gain, a 0= k i / m , k i is the current stiffness coefficient, k 1>0, k 2>0, k 3>0, k 4>0, s is the sliding surface, and also the system state, y 1 is the rotor displacement value, x 2 for x The differential of 1, y r is the displacement reference value, e 2 Yes e The derivative of 1, e 1 is the deviation between the displacement reference value and the rotor displacement value; a >0, 1< b <2.

8. An active electromagnetic bearing control system, characterized in that: A super helical sliding mode controller comprising any one of claims 1 to 7, and an active electromagnetic bearing, wherein the active electromagnetic bearing is used to input a control quantity of the super helical sliding mode controller i c With aggregate interference d , resulting in rotor displacement y 1.

9. The control method of an active electromagnetic bearing control system according to claim 8, characterized in that: The following steps are involved: Enter the displacement reference value y r , rotor displacement y 1 to the super helical sliding mode controller, calculate the control quantity of the super helical sliding mode controller i c ; The amount of control i c With aggregate interference d To the input to the active electromagnetic bearing, generating rotor displacement y 1; The sliding surface s Perform positive and negative calculations to obtain sign(s) ,right sign(s) Integrate and multiply by the gain factor k 3. Get ; The sliding surface s First take the modulus value through the exponential coefficient c Taking the exponent of it gives , multiplied by the sign function result sign(s) , integrate the result, and then multiply it by the gain factor k 4. Get ; Will and Taking the difference, we get the super-helical sliding mode reaching law s= .

10. The control method of an active electromagnetic bearing control system according to claim 9, characterized in that: After the super-helical sliding mode reaching law s is obtained, the super-helical sliding mode reaching law s is input as the sliding mode surface into the symbolic function device for cyclic calculation.

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