Preheating method of magnetic suspension motor and magnetic suspension motor

Abstract

The invention provides a preheating method of a magnetic suspension motor and the magnetic suspension motor, and the method comprises the steps: controlling the input current of a radial bearing coil, enabling a rotor to carry out the circular motion in a first plane, and enabling the first plane to be a plane perpendicular to the axis of the rotor; the input current of an axial bearing coil is controlled, so that the rotor does circumferential motion in the first plane and does axial motion in the axial lead direction of the rotor at the same time, and eddy current is generated; a rotor is preheated through eddy current, and the rotor is made of metal materials. By changing the input current of the original radial bearing coil and axial bearing coil in the magnetic suspension motor, the eddy current is generated at the position of the rotor, the rotor is preheated by using the eddy current, an additional heating structure does not need to be added, the design structure of the magnetic suspension motor does not need to be changed, and stable and efficient operation of the magnetic suspension motor is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of preheating a magnetic levitation motor, and in particular to a preheating method for a magnetic levitation motor and a magnetic levitation motor. Background Art

[0002] The magnetic levitation motor uses the electromagnetic force generated by the magnetic bearing to suspend the rotor at a given position, so that the rotor and the bearing are not in contact, achieving frictionless and high-speed operation. During operation, the magnetic levitation motor needs to generate electromagnetic force through radial magnetic bearings and axial magnetic bearings to control the suspension position of the rotor.

[0003] During the process of starting and running the magnetic levitation motor, as the temperature rises, the rotor expands due to heat, which causes the diameter of the rotor to gradually increase during this period. The rotor is suspended on the magnetic bearing by magnetic levitation. If the expansion of the rotor reduces the suspension air gap, the characteristics of the magnetic bearing will change, thus affecting the stability and load-bearing capacity of the magnetic bearing. The characteristics of the magnetic bearing, such as changes in stiffness and damping, will affect the dynamic performance and stability of the rotor system.

[0004] In addition, the expansion of the rotor will cause the fixed frequency to shift. The fixed frequency refers to the frequency of the natural vibration of the system when there is no external excitation. The expansion of the rotor in the radial direction will affect the mass distribution and stiffness of the rotor, thereby changing its natural frequency. In order to avoid changes in the fixed frequency, the prior art usually adds a notch filter with a certain bandwidth to the magnetic levitation controller system to avoid changes in the fixed frequency. However, the design of the notch filter is usually based on a specific natural frequency. The fixed frequency shift caused by temperature changes may cause the frequency response of the notch filter to not match the actual natural frequency, thereby reducing the filtering effect of the notch filter and affecting the stability of the system.

[0005] In summary, in order to ensure the operating stability of the magnetic levitation motor during the startup process, it is necessary to avoid the problem of the rotor expanding during operation. In order to ensure the dimensional stability of the rotor in the radial direction, the prior art sets a heating component around the rotor in the magnetic levitation motor to preheat the rotor so that the rotor expands to a preset size before operation, thereby avoiding the rotor being affected by temperature during operation, causing dimensional changes and affecting the operating stability of the magnetic levitation motor. However, the method of adding a heating component in the prior art increases the design difficulty of the magnetic levitation motor. The need to reserve additional space for placement also increases the size and floor space of the magnetic levitation motor, which is not conducive to the miniaturization and simplification of the magnetic levitation motor. Summary of the invention

[0006] In order to overcome the problems existing in the related art, one of the objects of the present invention is to provide a preheating method for a magnetic levitation motor. By changing the input current of the original radial bearing coil and the axial bearing coil in the magnetic levitation motor, eddy currents are generated at the rotor position, and the rotor is preheated by the eddy currents. There is no need to add additional heating structures or change the design structure of the magnetic levitation motor, thereby ensuring the smooth and efficient operation of the magnetic levitation motor.

[0007] A preheating method for a magnetic levitation motor, comprising:

[0008] Controlling the input current of the radial bearing coil so that the rotor performs circular motion in a first plane, wherein the first plane refers to a plane perpendicular to the axis of the rotor; the radial bearing coil is nested in the periphery of the radial magnetic bearing, and the axis of the radial magnetic bearing is perpendicular to the axis of the rotor;

[0009] Controlling the input current of the axial bearing coil so that the rotor performs circular motion in the first plane and performs axial motion along the axis of the rotor to generate eddy current; the axial bearing coil is nested in the periphery of the axial magnetic bearing, and the axis of the axial magnetic bearing is parallel to the axis of the rotor;

[0010] The rotor is preheated by using eddy current, and the rotor is made of metal material.

[0011] In the present application, the axial magnetic bearing and radial magnetic bearing belong to the original structure of the magnetic levitation motor. By changing the input current of the magnetic bearing peripheral bearing coil, the rotor can be moved in the radial and axial directions, thereby causing the rotor to generate eddy currents. Since the rotor is made of metal material, eddy currents generated in the metal material will generate heat, thereby achieving preheating of the rotor. The preheating process of the present application occurs before the magnetic levitation motor is started. The purpose is to stabilize the influence of the rotor expansion caused by temperature changes on the magnetic bearing characteristics and the deviation of the rotor fixed frequency, thereby ensuring that the magnetic levitation motor can run smoothly and efficiently.

[0012] In a preferred technical solution of the present invention, it also includes: during the eddy current preheating process, the diameter of the rotor is measured until the diameter of the rotor is equal to a preset value, and the eddy current preheating is stopped.

[0013] Eddy current preheating occurs before the magnetic levitation motor starts running. During the stable operation of the magnetic levitation motor, the temperature of the rotor can be maintained within a relatively stable temperature range. This application can determine the temperature and rotor size after normal stable operation of the magnetic levitation motor based on the parameters of the magnetic levitation motor, and then determine the end point of eddy current preheating based on the rotor size during stable operation, ensuring that the rotor size after eddy current preheating is basically consistent with the rotor size after the normal operation of the magnetic levitation motor. By measuring the rotor diameter, the end time of eddy current preheating can be accurately controlled, which can not only ensure a good preheating effect, but also avoid energy consumption caused by the preheating time process.

[0014] In a preferred technical solution of the present invention, a protective bearing is arranged on the outer periphery of the rotor, and the axis of the protective bearing is parallel to the axis of the rotor; the protective bearing is sleeved on the outer periphery of the rotor; and the rotor performs circular motion along the inner side wall of the protective bearing in a first plane.

[0015] The protective bearing is a ring-shaped structure located outside the rotor and having an inner diameter larger than the outer diameter of the rotor. The protective bearing is used to limit the position of the rotor when it makes circular motion in the first plane to prevent the circular motion of the rotor from exceeding a certain range. By limiting the position of the protective bearing, it can be ensured that when the rotor rotates in the first plane, it makes circular motion along the inner wall of the protective bearing, thereby achieving stable operation of the rotor in the first plane.

[0016] In a preferred technical solution of the present invention, M radial magnetic bearings are provided, where M is an integer greater than 1, and radial bearing coils are respectively sleeved at both ends of the radial magnetic bearing. The 2M radial bearing coils are distributed in a circle in the first plane with the axis of the protective bearing as the center.

[0017] The axis of the radial magnetic bearing is perpendicular to the axis of the rotor, and radial bearing coils are sleeved at both ends of the radial magnetic bearing, so that the radial bearing coils surround the outer circumference of the rotor. In order to realize the circular motion of the rotor in the first plane, it is necessary to set the number of radial magnetic bearings to be greater than or equal to two to ensure that the 2M radial bearing coils are distributed in a circle in the first plane with the axis of the protective bearing as the center. The circular motion of the rotor in the first plane needs to rely on the current changes in different radial bearing coils to attract the rotor to various positions of the circumference in turn, thereby realizing circular motion.

[0018] In a preferred technical solution of the present invention, the rotor is caused to perform circular motion in the first plane by changing the input current of the 2M radial bearing coils.

[0019] The axis of the radial magnetic bearing is perpendicular to the axis of the rotor, and radial bearing coils are sleeved at both ends of the radial magnetic bearing, so that the radial bearing coils surround the outer circumference of the rotor. In order to realize the circular motion of the rotor in the first plane, it is necessary to set the number of radial magnetic bearings to be greater than or equal to two to ensure that the 2M radial bearing coils are distributed in a circle in the first plane with the axis of the protective bearing as the center. The circular motion of the rotor in the first plane needs to rely on the current changes in different radial bearing coils to attract the rotor to various positions of the circumference in turn, thereby realizing circular motion.

[0020] In a preferred technical solution of the present invention, there are two radial magnetic bearings, and radial bearing coils are respectively sleeved at both ends of the radial magnetic bearings. The four radial bearing coils are distributed in a circle with the axis of the protective bearing as the center in the first plane. In the clockwise direction, the four radial bearing coils are defined as the first radial bearing coil, the second radial bearing coil, the third radial bearing coil and the fourth radial bearing coil.

[0021] At time t0-t1, the input current of the first radial bearing coil is set to be greater than the input currents of the second radial bearing coil, the third radial bearing coil and the fourth radial bearing coil, so that the rotor is attracted to a position close to the first radial bearing coil;

[0022] At time t1-t2, the input current of the second radial bearing coil is set to be greater than the input currents of the first radial bearing coil, the third radial bearing coil and the fourth radial bearing coil, so that the rotor is attracted to a position close to the second radial bearing coil;

[0023] At time t2-t3, the input current of the third radial bearing coil is set to be greater than the input currents of the first radial bearing coil, the second radial bearing coil and the fourth radial bearing coil, so that the rotor is attracted to a position close to the third radial bearing coil;

[0024] At time t3-t4, the input current of the fourth radial bearing coil is set to be greater than the input currents of the first radial bearing coil, the second radial bearing coil and the third radial bearing coil, so that the rotor is attracted to a position close to the fourth radial bearing coil; to achieve circular motion of the rotor in the first plane.

[0025] The present application can realize the circular motion of the rotor in the first plane only by changing the input current value of the radial bearing coil. The control method is simple and convenient, and no other control components need to be added, thereby simplifying the rotor preheating structure and method.

[0026] In a preferred technical solution of the present invention, M radial magnetic bearings form a radial control component, and N radial control components are provided, and the N radial control components are distributed in sequence along the axis of the rotor; N is an integer greater than 0.

[0027] Since the size of the rotor in the axial direction is relatively large, and the radial bearing coil in each radial control component can only overlap with the rotor part in the axial direction, in order to ensure that each position of the rotor can perform circular motion in the first plane, the present application can set up multiple radial control components to ensure that each radial control component can exert circular motion attraction on the corresponding position of the rotor, thereby ensuring that the circular motion of the rotor is smooth and smooth.

[0028] In a preferred technical solution of the present invention, the axial magnetic bearing is located on one side of the rotor, and axial bearing coils are sleeved on both ends of the axial magnetic bearing; by changing the input current of the two axial bearing coils, the rotor is made to move axially along the axis of the rotor.

[0029] In a preferred technical solution of the present invention, it also includes a thrust plate, which is located between two axial bearing coils and is fixedly connected to the rotor.

[0030] The thrust plate and the rotor are both made of metal materials. The setting of the thrust plate can ensure the stable reciprocating movement of the rotor in the direction of its axial center line.

[0031] A second object of the present application is to provide a magnetic levitation motor that is preheated using the preheating method described above.

[0032] The magnetic levitation motor provided by the present application does not require the addition of an additional heating component. It utilizes the changes in the input current of the bearing coils in the radial magnetic bearings and the axial magnetic bearings to move the rotor in the radial and axial directions, generate eddy currents, and preheat the rotor using the eddy current heating principle. The structure of the magnetic levitation motor of the present application does not need to be redesigned, reducing the design difficulty.

[0033] The beneficial effects of the present invention are:

[0034] The present invention provides a preheating method for a magnetic levitation motor, which utilizes its original radial magnetic bearings and axial magnetic bearings to realize eddy current preheating of the rotor, specifically including: controlling the input current of the radial bearing coil so that the rotor makes a circular motion in the first plane, and controlling the input current of the axial bearing coil so that the rotor makes a circular motion in the first plane while making an axial motion along the axis of the rotor to generate eddy currents; utilizing the eddy currents to preheat the rotor. In this application, the first plane refers to a plane perpendicular to the axis of the rotor; the radial bearing coil is nested in the periphery of the radial magnetic bearing, and the axis of the radial magnetic bearing is perpendicular to the axis of the rotor; the axial bearing coil is nested in the periphery of the axial magnetic bearing, and the axis of the axial magnetic bearing is parallel to the axis of the rotor. In the present application, the axial magnetic bearing and radial magnetic bearing belong to the original structure of the magnetic levitation motor. By changing the input current of the magnetic bearing peripheral bearing coil, the rotor can be moved in the radial and axial directions, thereby causing the rotor to generate eddy currents. Since the rotor is made of metal material, eddy currents generated in the metal material will generate heat, thereby achieving preheating of the rotor. The preheating process of the present application occurs before the magnetic levitation motor is started. The purpose is to stabilize the influence of the rotor expansion caused by temperature changes on the magnetic bearing characteristics and the deviation of the rotor fixed frequency, thereby ensuring that the magnetic levitation motor can run smoothly and efficiently.

[0035] The magnetic levitation motor provided by the present application does not require the addition of an additional heating component. It utilizes the changes in the input current of the bearing coils in the radial magnetic bearings and the axial magnetic bearings to move the rotor in the radial and axial directions, generate eddy currents, and preheat the rotor using the eddy current heating principle. The structure of the magnetic levitation motor of the present application does not need to be redesigned, reducing the design difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the preheating method for this application;

[0037] Figure 2 This is a schematic diagram of one distribution of radial bearing coils in this application;

[0038] Figure 3 This is a schematic diagram of one distribution of the axial bearing coils in this application;

[0039] Figure 4 A schematic diagram of one distribution of radial magnetic bearings in this application;

[0040] Figure 5 It is a side view of the position of the position sensor in Example 3;

[0041] Figure 6 is a top view of the position of the position sensor in Example 3;

[0042] Figure 7The figure is a circuit diagram of one type of power amplifier.

[0043] Reference numerals:

[0044] 11. Radial magnetic bearing; 121. First radial bearing coil; 122. Second radial bearing coil; 123. Third radial bearing coil; 124. Fourth radial bearing coil; 13. Protective bearing; 14. First position sensor; 15. Second position sensor; 16. Third position sensor; 17. Fourth position sensor; 211. First axial bearing coil; 212. Second axial bearing coil; 22. Thrust plate; 31. Rotor. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0046] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0047] It should be understood that although the terms "first", "second", "third", etc. may be used to describe various information in the present invention, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0048] Example 1

[0049] like Figure 1-Figure 7 As shown, a preheating method for a magnetic levitation motor includes:

[0050] S1: Control the input current of the radial bearing coil so that the rotor 31 performs circular motion in a first plane, where the first plane refers to a plane perpendicular to the axis of the rotor 31; the radial bearing coil is nested outside the radial magnetic bearing 11, and the axis of the radial magnetic bearing 11 is perpendicular to the axis of the rotor 31;

[0051] S2: Control the input current of the axial bearing coil so that the rotor 31 performs circular motion in the first plane and performs axial motion along the axis of the rotor 31 to generate eddy current; the axial bearing coil is nested in the periphery of the axial magnetic bearing, and the axis of the axial magnetic bearing is parallel to the axis of the rotor 31;

[0052] S3: preheating the rotor 31 by using eddy current, wherein the rotor 31 is made of metal material.

[0053] In the present application, the axial magnetic bearing and the radial magnetic bearing 11 belong to the original structure of the magnetic levitation motor. By changing the input current of the external bearing coil of the magnetic bearing, the movement of the rotor 31 in the radial and axial directions can be realized, thereby causing the rotor 31 to generate eddy currents. Since the rotor 31 is made of metal material, the eddy currents generated in the metal material will generate heat, thereby realizing the preheating of the rotor 31. The preheating process of the present application occurs before the magnetic levitation motor is started. The purpose is to stabilize the influence of the expansion of the rotor 31 caused by temperature changes on the magnetic bearing characteristics and the offset of the fixed frequency of the rotor 31, so as to ensure that the magnetic levitation motor can run smoothly and efficiently.

[0054] Example 2

[0055] like Figure 1-Figure 7 As shown, a preheating method for a magnetic levitation motor includes:

[0056] S1: Control the input current of the radial bearing coil so that the rotor 31 makes circular motion in a first plane, where the first plane refers to a plane perpendicular to the axis of the rotor 31; the radial bearing coil is nested outside the radial magnetic bearing 11, and the axis of the radial magnetic bearing 11 is perpendicular to the axis of the rotor 31.

[0057] Further, such as Figure 2 As shown, the outer periphery of the rotor described in the present application is provided with a protective bearing 13, and the axis of the protective bearing 13 is parallel to the axis of the rotor 31; the protective bearing 13 is sleeved on the outer periphery of the rotor 31; the rotor 31 performs circular motion along the inner side wall of the protective bearing 13 in the first plane.

[0058] The protective bearing 13 is an annular structure located outside the rotor 31 and having an inner diameter greater than the outer diameter of the rotor 31. The protective bearing 13 is used to limit the position of the rotor 31 when it makes a circular motion in the first plane, so as to prevent the circular motion of the rotor 31 from exceeding a certain range. By limiting the position of the protective bearing 13, it can be ensured that when the rotor 31 rotates in the first plane, it makes a circular motion along the inner side wall of the protective bearing 13, so as to realize the stable operation of the rotor 31 in the first plane.

[0059] in, Figure 2 The plane shown is one of the first planes.

[0060] Furthermore, the radial magnetic bearings 11 are provided with M, where M is an integer greater than 1, and radial bearing coils are respectively sleeved at both ends of the radial magnetic bearing 11. The 2M radial bearing coils are distributed in a circle in the first plane with the axis of the protective bearing 13 as the center.

[0061] like Figure 4 As shown, the axis of the radial magnetic bearing 11 is perpendicular to the axis of the rotor 31, and radial bearing coils are sleeved at both ends of the radial magnetic bearing 11, so that the radial bearing coils surround the outer circumference of the rotor 31. In order to realize the circular motion of the rotor 31 in the first plane, it is necessary to set the number of radial magnetic bearings 11 to be greater than or equal to two to ensure that the 2M radial bearing coils are distributed in a circle with the axis of the protective bearing 13 as the center in the first plane. The circular motion of the rotor 31 in the first plane needs to rely on the current changes in different radial bearing coils to attract the rotor 31 to various positions of the circumference in turn, thereby realizing the circular motion.

[0062] That is to say, the present application changes the input current of the 2M radial bearing coils so that the rotor 31 performs circular motion in the first plane.

[0063] In actual operation, when M is equal to 2, the four radial bearing coils are evenly distributed at an angle of 90°; when M is equal to 3, the six radial bearing coils are evenly distributed at an angle of 60°. When M is equal to 4, the eight radial bearing coils are evenly distributed at an angle of 45°. From the perspective of driving force, the larger the value of M, the more stable the circular motion of the rotor 31 in the first plane can be. From the perspective of simplified structure, the smaller the value of M, the more streamlined the structure of the magnetic levitation motor can be. In actual operation, two radial magnetic bearings 11 can be designed.

[0064] Further, the circular motion is described as follows, taking the number of radial magnetic bearings 11 as 2 as an example: Figure 2 and Figure 4, radial bearing coils are respectively sleeved at both ends of the radial magnetic bearing 11, and the four radial bearing coils are distributed in a circle with the axis of the protective bearing 13 as the center in the first plane. In the clockwise direction, the four radial bearing coils are defined as the first radial bearing coil 121, the second radial bearing coil 122, the third radial bearing coil 123 and the fourth radial bearing coil 124, and the first radial bearing coil 121 and the third radial bearing coil 123 are sleeved on the same radial magnetic bearing 11; the second radial bearing coil 122 and the fourth radial bearing coil 124 are sleeved on the same radial bearing. In the following description, the moments t0, t1, t2, t3, and t4 are delayed in time sequence.

[0065] S11: At time t0-t1, the input current of the first radial bearing coil 121 is set to be greater than the input current of the second radial bearing coil 122, the third radial bearing coil 123 and the fourth radial bearing coil 124, so that the rotor 31 is attracted to a position close to the first radial bearing coil 121; Figure 2 The dotted line where the rotor 31 is located is shown. The input current value of the first radial bearing coil 121 and the input current values ​​of other radial bearing coils can be determined according to the model of the rotor 31, etc., to ensure that under the corresponding input current value, the suction force of the first radial bearing coil 121 on the rotor 31 is greater than the suction force of other radial bearing coils on the rotor 31, and the rotor 31 can be sucked to the position of the first radial bearing coil 121.

[0066] S12: At time t1-t2, the input current of the second radial bearing coil 122 is set to be greater than the input current of the first radial bearing coil 121, the third radial bearing coil 123 and the fourth radial bearing coil 124, so that the rotor 31 is attracted to a position close to the second radial bearing coil 122; Figure 2 The actual position of the middle rotor 31 is shown.

[0067] S13: at time t2-t3, the input current of the third radial bearing coil 123 is set to be greater than the input currents of the first radial bearing coil 121, the second radial bearing coil 122 and the fourth radial bearing coil 124, so that the rotor 31 is attracted to a position close to the third radial bearing coil 123;

[0068] S14: At time t3-t4, the input current of the fourth radial bearing coil 124 is set to be greater than the input current of the first radial bearing coil 121 , the second radial bearing coil 122 and the third radial bearing coil 123 , so that the rotor 31 is attracted to a position close to the fourth radial bearing coil 124 .

[0069] The above steps S11-S14 are repeated in a reciprocating cycle: by the above reciprocating control of the input current values ​​of the four radial bearing coils, the circular motion of the rotor 31 in the first plane can be achieved.

[0070] The present application can realize the circular motion of the rotor 31 in the first plane only by changing the input current value of the radial bearing coil. The control method is simple and convenient, and no other control components need to be added, thereby simplifying the preheating structure and method of the rotor 31.

[0071] Furthermore, the M radial magnetic bearings 11 form a radial control component, and N radial control components are provided, and the N radial control components are distributed in sequence along the axis of the rotor 31 .

[0072] Since the size of the rotor 31 in the axial direction is relatively large, and the radial bearing coil in each radial control component can only partially overlap with the rotor 31 in the axial direction, in order to ensure that each position of the rotor 31 can perform circular motion in the first plane, the present application can set up multiple radial control components to ensure that each radial control component can exert circular motion attraction on the corresponding position of the rotor 31, thereby ensuring that the circular motion of the rotor 31 is smooth and smooth.

[0073] like Figure 4 As shown, N is equal to 2, and two radial control components are respectively arranged at the front end and the rear end of the axis direction of the rotor 31 to apply circular motion suction to the front end and the rear end of the rotor 31. By the same token, when N is equal to 1, a radial control component can be arranged at the center position of the axis direction of the rotor 31 to apply circular motion suction to the center of the rotor 31. When N is equal to 3, three radial control components can be respectively arranged at the front end, the middle and the rear end of the axis direction of the rotor 31 to apply circular motion suction to the front end, the center and the rear end of the rotor 31. When N is greater than 3, N radial control components can be arranged to be evenly distributed along the axis of the rotor 31 in sequence.

[0074] S2: Control the input current of the axial bearing coil so that the rotor 31 makes a circular motion in the first plane and at the same time makes an axial motion along the axis of the rotor 31 to generate eddy current; the axial bearing coil is nested in the periphery of the axial magnetic bearing, and the axis of the axial magnetic bearing is parallel to the axis of the rotor 31.

[0075] Furthermore, the axial magnetic bearing is located on one side of the rotor 31 , and axial bearing coils are sleeved on both ends of the axial magnetic bearing; by changing the input current of the two axial bearing coils, the rotor 31 is made to move axially along the axis direction of the rotor 31 .

[0076] like Figure 3As shown, the axis of the axial magnetic bearing is parallel to the axis of the rotor 31, and the two axial bearing coils are respectively sleeved on both ends of the axial magnetic bearing, so that the axial bearing coils are distributed along the axis of the rotor 31. In order to ensure that the axial bearing coils can generate suction on the rotor 31 in the direction of the axis, the present application also provides a thrust plate 22, which is located between the two axial bearing coils and is fixedly connected to the rotor 31.

[0077] The thrust plate 22 and the rotor 31 are both made of metal material. The arrangement of the thrust plate 22 can ensure the stable reciprocating movement of the rotor 31 in the direction of its axial center line.

[0078] like Figure 3 As shown, the axial bearing coils on the left and right sides are set to be the first axial bearing coil 211 and the second axial bearing coil 212 respectively; the moments t0', t1', and t2' are delayed in time sequence. The axial movement of the rotor 31 in this step specifically includes:

[0079] S21: At time t0'-t1', the input current of the first axial bearing coil 211 is set to be greater than the input current of the second axial bearing coil 212, so that the thrust plate 22 drives the rotor 31 to be attracted to a position close to the first axial bearing coil 211; Figure 3 The dotted line where the middle thrust disc 22 is located is shown. Among them, the input current value of the first axial bearing coil 211 and the input current value of the second axial bearing coil 212 can be determined according to the model of the rotor 31, etc., to ensure that under the corresponding input current value, the suction force of the first axial bearing coil 211 on the rotor 31 is greater than the suction force of the second axial bearing coil 212 on the rotor 31, and the rotor 31 can be sucked to the position of the first axial bearing coil 211.

[0080] S22: At time t1'-t2', the input current of the second axial bearing coil 212 is set to be greater than the input current of the first axial bearing coil 211, so that the thrust plate 22 drives the rotor 31 to be attracted to a position close to the second axial bearing coil 212; Figure 3 The solid line position of the middle thrust plate 22 is shown.

[0081] The above steps S21-S22 are repeated in a reciprocating cycle: by reciprocatingly controlling the input current values ​​of the two axial bearing coils, the rotor 31 can be reciprocated in the axis direction.

[0082] The present application may provide one axial magnetic bearing or multiple axial magnetic bearings, and the multiple axial magnetic bearings are evenly distributed along the circumferential direction of the rotor 31. The larger the number of axial magnetic bearings, the more the rotor 31 can be driven to move in the axial direction at various positions in the circumferential direction of the rotor 31.

[0083] The rotor 31 of the present application moves back and forth on the axis line and also performs circular motion in the first plane. In order to ensure the heating effect of the rotor 31, the present application stipulates that: when the input current of the first radial bearing coil 121 is greater than the input current of the second radial bearing coil 122, the third radial bearing coil 123 and the fourth radial bearing coil 124; and the input current of the third radial bearing coil 123 is greater than the input current of the first radial bearing coil 121, the second radial bearing coil 122 and the fourth radial bearing coil 124, the input current of the first axial bearing coil 211 is controlled to be greater than the input current of the second axial bearing coil 212 at the same time.

[0084] When the input current of the second radial bearing coil 122 is greater than the input current of the first radial bearing coil 121, the third radial bearing coil 123 and the fourth radial bearing coil 124, and the input current of the fourth radial bearing coil 124 is greater than the input current of the first radial bearing coil 121, the second radial bearing coil 122 and the third radial bearing coil 123, the input current of the second axial bearing coil 212 is simultaneously controlled to be greater than the input current of the first axial bearing coil 211.

[0085] That is to say, when step S11 and step S13 occur, step S21 occurs simultaneously; when step S12 and step S13 occur, step S22 occurs simultaneously; this ensures the stability of eddy current generation, thereby achieving stable preheating of the rotor 31.

[0086] S3: preheating the rotor 31 by using eddy current, wherein the rotor 31 is made of metal material.

[0087] S4: In the eddy current preheating process of the present application, it is necessary to measure the diameter of the rotor 31 until the diameter of the rotor 31 is equal to a preset value, and then stop the eddy current preheating.

[0088] Eddy current preheating occurs before the magnetic levitation motor starts running. During the stable operation of the magnetic levitation motor, the temperature of the rotor 31 can be maintained within a relatively stable temperature range. This application can determine the temperature and the size of the rotor 31 after normal stable operation based on the parameters of the magnetic levitation motor, and then determine the end point of eddy current preheating based on the size of the rotor 31 during stable operation, ensuring that the size of the rotor 31 after eddy current preheating is basically consistent with the size of the rotor 31 after the normal operation of the magnetic levitation motor. By measuring the diameter of the rotor 31, the end time of eddy current preheating can be accurately controlled, which can not only ensure a good preheating effect, but also avoid energy consumption caused by the preheating time process.

[0089] As another specific embodiment, the present application can also obtain the temperature of the magnetic levitation motor after stable operation, and monitor the eddy current heating temperature in real time during eddy current preheating. When the eddy current heating temperature reaches the stable operating temperature of the magnetic levitation motor, it is maintained for a period of time, that is, the eddy current heating is stopped. The reason for maintaining it for a period of time is to avoid the expansion of the rotor 31 not being stable when the operating temperature is just reached.

[0090] Example 3

[0091] This embodiment includes the preheating method in Embodiment 2, which will not be described in detail here. The difference from Embodiment 2 is that this embodiment limits the number of radial control components to two, which are respectively arranged at the front end and the rear end of the rotor 31. Figure 5 and Figure 6 shown.

[0092] In this embodiment, during the eddy current preheating process, a position sensor is used to measure the diameter of the rotor 31 until the diameter of the rotor 31 is equal to a preset value, and the eddy current preheating is stopped.

[0093] Specifically, the position sensors include four, which are respectively arranged at the two ends of the radial magnetic bearings 11 distributed in the same direction in the two groups of radial control components, such as Figure 5 As shown, the first position sensor 14 and the second position sensor 15 are respectively located in the radial magnetic bearing 11 of the radial control assembly at the front end; the third position sensor 16 and the fourth position sensor 17 are respectively located in the radial magnetic bearing 11 of the radial control assembly at the rear end.

[0094] When the rotor 31 performs circular motion in the first plane, its front end and rear end will approach the first position sensor 14 and the third position sensor 16 at the same time. At this time, the first position sensor 14 and the third position sensor 16 can measure the distance between the front end and the rear end of the rotor 31 and the first position sensor 14 and the third position sensor 16; at the same time, the second position sensor 15 and the fourth position sensor 17 can measure the distance between the front end and the rear end of the rotor 31 and the second position sensor 17. Since the first position sensor 14 and the second position sensor 15 are respectively fixed at the two ends of the same radial magnetic bearing 11, that is, the position between the two is fixed, the expansion degree of the rotor 31 can be fed back by the sum of the distance between the first position sensor 14 and the rotor 31 and the distance between the second position sensor 15 and the rotor 31. If the sum of the distance between the first position sensor 14 and the rotor 31 and the distance between the second position sensor 15 and the rotor 31 is larger, the expansion degree of the rotor 31 is smaller; if the sum of the distance between the first position sensor 14 and the rotor 31 and the distance between the second position sensor 15 and the rotor 31 is smaller, the expansion degree of the rotor 31 is larger. Whether the rotor 31 has expanded to a preset value is then determined based on the sum of the distance between the first position sensor 14 and the rotor 31 and the distance between the second position sensor 15 and the rotor 31 .

[0095] The present application can calculate the expansion degree of the front end of the rotor 31 through the first position sensor 14 and the second position sensor 15, and can calculate the expansion degree of the rear end of the rotor 31 according to the third position sensor 16 and the fourth position sensor 17. The combination of the two can obtain the overall expansion degree of the rotor 31.

[0096] Similarly, when the rotor 31 performs circular motion in the first plane, its front end and rear end will simultaneously approach the second position sensor 15 and the fourth position sensor 17. At this time, the first position sensor 14 and the third position sensor 16 can measure the distance between the front end and the rear end of the rotor 31 and the second position sensor 15 and the fourth position sensor 17. At the same time, the second position sensor 15 and the fourth position sensor 17 can measure the distance between the front end and the rear end of the rotor 31 and the rotor 31. Similar to the above principle, no detailed description is given.

[0097] The present application can calculate the diameter of the rotor 31 only by the feedback value of the position sensor when the rotor 31 rotates to the second position sensor 15 and the fourth position sensor 17, or can calculate the diameter of the rotor 31 only by the feedback value of the position sensor when the rotor 31 rotates to the first position sensor 14 and the third position sensor 16; the diameter of the rotor 31 can also be calculated by the feedback value of the position sensor when the rotor 31 rotates to the second position sensor 15 and the fourth position sensor 17, and the diameter of the rotor 31 can be calculated by the feedback value of the position sensor when the rotor 31 rotates to the first position sensor 14 and the third position sensor 16, and the average of the two is used to obtain the diameter of the rotor 31.

[0098] Through the preheating method and detection method in the present application, the size of the rotor 31 is maintained within a stable range, thereby ensuring the stability of the air gap between the rotor 31 and the radial magnetic bearing 11, thereby stabilizing the influence of the expansion of the rotor 31 caused by temperature changes on the magnetic bearing characteristics and the deviation of the fixed frequency of the rotor 31, ensuring that the magnetic levitation motor can run smoothly and efficiently.

[0099] Example 4

[0100] This embodiment includes the preheating method in Embodiment 2, which will not be described in detail here. The difference from Embodiment 2 is that this embodiment uses a power amplifier to control the input current of each bearing coil, wherein the input current of two radial bearing coils arranged on the same radial magnetic bearing 11 is controlled by the same power amplifier, and the input current of two axial bearing coils arranged on the same axial magnetic bearing is controlled by the same power amplifier. The following is explained through a circuit diagram of one of the power amplifiers, which is used to control the input current value of the first axial bearing coil 211 and the second axial bearing coil 212.

[0101] like Figure 7 As shown, the current in the bearing coil is controlled by the power amplifier, and the current is controlled by the control chip outputting the PWM signal to control the switch of the switch tube. The larger the PWM duty cycle, the larger the input current. If you want to modify the input current of the first axial bearing coil 211 and the second axial bearing coil 212, you need to close Figure 7 The switch tube M1, switch tube M4, and switch tube M5 in the circuit. The PWM signal of the switch tube M4 is set to a constant 50% duty cycle, and the input current value of the first axial bearing coil 211 and the second axial bearing coil 212 is modified by modifying the PWM duty cycle of the switch tubes M1 and M5. For example, if the first axial bearing coil 211 corresponds to the switch tube M1, then increasing the PWM duty cycle of the switch tube M1 can increase the input current of the first axial bearing coil 211, thereby ensuring that the input current of the first axial bearing coil 211 is greater than the input current of the second axial bearing coil 212. Similarly, if the second axial bearing coil 212 corresponds to the switch tube M5, then increasing the PWM duty cycle of the switch tube M5 can increase the input current of the second axial bearing coil 212, thereby ensuring that the input current of the second axial bearing coil 212 is greater than the input current of the first and second axial bearing coils.

[0102] The present application also discloses a magnetic levitation motor, which uses the preheating method described above to preheat the rotor 31, and then officially starts the magnetic levitation motor for operation. The magnetic levitation motor provided by the present application does not require the addition of an additional heating component, and utilizes the change in the input current of the bearing coils in the radial magnetic bearing 11 and the axial magnetic bearing to move the rotor 31 in the radial and axial directions, generate eddy currents, and preheat the rotor 31 using the eddy current heating principle; the structure of the magnetic levitation motor of the present application does not need to be redesigned, which reduces the design difficulty.

[0103] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings. In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0104] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0105] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preheating method for a magnetic levitation motor, characterized in that: include: Controlling the input current of the radial bearing coil so that the rotor (31) performs circular motion in a first plane, the first plane being a plane perpendicular to the axis of the rotor (31); the radial bearing coil is nested on the periphery of the radial magnetic bearing (11), and the axis of the radial magnetic bearing (11) is perpendicular to the axis of the rotor (31); Controlling the input current of the axial bearing coil so that the rotor (31) performs circular motion in a first plane and performs axial motion along the axis of the rotor (31) to generate eddy current; the axial bearing coil is nested in the periphery of the axial magnetic bearing, and the axis of the axial magnetic bearing is parallel to the axis of the rotor (31); The rotor (31) is preheated by using eddy current, and the rotor (31) is made of metal material.

2. A preheating method for a magnetic levitation motor according to claim 1, characterized in that: Also includes: During the eddy current preheating process, the diameter of the rotor (31) is measured until the diameter of the rotor (31) is equal to a preset value, and the eddy current preheating is stopped.

3. A preheating method for a magnetic levitation motor according to claim 1, characterized in that: A protective bearing (13) is arranged on the outer periphery of the rotor, and the axis of the protective bearing (13) is parallel to the axis of the rotor (31); the protective bearing (13) is sleeved on the outer periphery of the rotor (31); and the rotor (31) performs circular motion along the inner side wall of the protective bearing (13) in a first plane.

4. A preheating method for a magnetic levitation motor according to claim 3, characterized in that: The radial magnetic bearings (11) are provided with M, where M is an integer greater than 1. Both ends of the radial magnetic bearings (11) are respectively sleeved with radial bearing coils, and the 2M radial bearing coils are distributed in a circle in a first plane with the axis of the protective bearing (13) as the center.

5. A preheating method for a magnetic levitation motor according to claim 4, characterized in that: By changing the input current of 2M radial bearing coils, the rotor (31) is made to perform circular motion in a first plane.

6. A preheating method for a magnetic levitation motor according to claim 3, characterized in that: There are two radial magnetic bearings (11), and radial bearing coils are respectively sleeved at both ends of the radial magnetic bearings (11). The four radial bearing coils are distributed in a circle in a first plane with the axis of the protective bearing (13) as the center. In the clockwise direction, the four radial bearing coils are defined as a first radial bearing coil (121), a second radial bearing coil (122), a third radial bearing coil (123), and a fourth radial bearing coil (124); At time t0-t1, the input current of the first radial bearing coil (121) is set to be greater than the input current of the second radial bearing coil (122), the third radial bearing coil (123) and the fourth radial bearing coil (124), so that the rotor (31) is attracted to a position close to the first radial bearing coil (121); At time t1-t2, the input current of the second radial bearing coil (122) is set to be greater than the input current of the first radial bearing coil (121), the third radial bearing coil (123) and the fourth radial bearing coil (124), so that the rotor (31) is attracted to a position close to the second radial bearing coil (122); At time t2-t3, the input current of the third radial bearing coil (123) is set to be greater than the input currents of the first radial bearing coil (121), the second radial bearing coil (122) and the fourth radial bearing coil (124), so that the rotor (31) is attracted to a position close to the third radial bearing coil (123); At time t3-t4, the input current of the fourth radial bearing coil (124) is set to be greater than the input current of the first radial bearing coil (121), the second radial bearing coil (122) and the third radial bearing coil (123), so that the rotor (31) is attracted to a position close to the fourth radial bearing coil (124); so as to realize the circular motion of the rotor (31) in the first plane.

7. A preheating method for a magnetic levitation motor according to claim 3, characterized in that: The M radial magnetic bearings (11) form a radial control component, and the N radial control components are provided, and the N radial control components are distributed in sequence along the axis of the rotor (31); N is an integer greater than 0.

8. The preheating method of a magnetic levitation motor according to claim 1, characterized in that: The axial magnetic bearing is located on one side of the rotor (31), and axial bearing coils are sleeved on both ends of the axial magnetic bearing; by changing the input current of the two axial bearing coils, the rotor (31) is caused to move axially along the axis direction of the rotor (31).

9. A method for preheating a magnetic levitation motor according to claim 8, characterized in that: It also includes a thrust disk (22), wherein the thrust disk (22) is located between two axial bearing coils, and the thrust disk (22) is fixedly connected to the rotor (31).

10. A magnetic levitation motor, characterized in that: Preheating is performed using the preheating method described in any one of claims 1 to 9.

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