FI128371B - A stator module for an axial magnetic bearing - Google Patents

A stator module for an axial magnetic bearing Download PDF

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Publication number
FI128371B
FI128371B FI20165629A FI20165629A FI128371B FI 128371 B FI128371 B FI 128371B FI 20165629 A FI20165629 A FI 20165629A FI 20165629 A FI20165629 A FI 20165629A FI 128371 B FI128371 B FI 128371B
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FI
Finland
Prior art keywords
magnetic
magnetic core
rotor
axial
section
Prior art date
Application number
FI20165629A
Other languages
Finnish (fi)
Swedish (sv)
Other versions
FI20165629A (en
Inventor
Rafal Jastrzebski
Antti Suikki
Original Assignee
Lappeenrannan Teknillinen Yliopisto
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lappeenrannan Teknillinen Yliopisto filed Critical Lappeenrannan Teknillinen Yliopisto
Priority to FI20165629A priority Critical patent/FI128371B/en
Priority to PCT/FI2017/050585 priority patent/WO2018037158A1/en
Publication of FI20165629A publication Critical patent/FI20165629A/en
Application granted granted Critical
Publication of FI128371B publication Critical patent/FI128371B/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
    • F16C32/0406—Magnetic bearings
    • F16C32/044—Active magnetic bearings
    • F16C32/0459—Details of the magnetic circuit
    • F16C32/0461—Details of the magnetic circuit of stationary parts of the magnetic circuit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
    • F16C32/0406—Magnetic bearings
    • F16C32/044—Active magnetic bearings
    • F16C32/0444—Details of devices to control the actuation of the electromagnets
    • F16C32/0446—Determination of the actual position of the moving member, e.g. details of sensors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
    • F16C32/0406—Magnetic bearings
    • F16C32/044—Active magnetic bearings
    • F16C32/0444—Details of devices to control the actuation of the electromagnets
    • F16C32/0451—Details of controllers, i.e. the units determining the power to be supplied, e.g. comparing elements, feedback arrangements with P.I.D. control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
    • F16C32/0406—Magnetic bearings
    • F16C32/044—Active magnetic bearings
    • F16C32/0474—Active magnetic bearings for rotary movement
    • F16C32/0476—Active magnetic bearings for rotary movement with active support of one degree of freedom, e.g. axial magnetic bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
    • F16C32/0406—Magnetic bearings
    • F16C32/044—Active magnetic bearings
    • F16C32/0474—Active magnetic bearings for rotary movement
    • F16C32/048—Active magnetic bearings for rotary movement with active support of two degrees of freedom, e.g. radial magnetic bearings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F3/00—Cores, Yokes, or armatures
    • H01F3/02—Cores, Yokes, or armatures made from sheets
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/14—Stator cores with salient poles
    • H02K1/141—Stator cores with salient poles consisting of C-shaped cores
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/14—Stator cores with salient poles
    • H02K1/145—Stator cores with salient poles having an annular coil, e.g. of the claw-pole type
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/14—Stator cores with salient poles
    • H02K1/146—Stator cores with salient poles consisting of a generally annular yoke with salient poles
    • H02K1/148—Sectional cores
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/18—Means for mounting or fastening magnetic stationary parts on to, or to, the stator structures
    • H02K1/182—Means for mounting or fastening magnetic stationary parts on to, or to, the stator structures to stators axially facing the rotor, i.e. with axial or conical air gap
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/20—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for measuring, monitoring, testing, protecting or switching
    • H02K11/21—Devices for sensing speed or position, or actuated thereby
    • H02K11/225—Detecting coils

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Magnetic Bearings And Hydrostatic Bearings (AREA)

Abstract

A stator module for an axial magnetic bearing comprises a one or more coils (101) for generating a magnetic flux and a magnetic core structure (102) for constituting a part of a magnetic circuit for the magnetic flux. The magnetic core structure comprises magnetic core elements (103-110) supported by a frame structure (111) of the stator module. Each magnetic core element comprises a first section for conducting a part of the magnetic flux to a rotor, a second section for conducting the part of the magnetic flux from the rotor, and a third section for conducting the part of the magnetic flux from the second section to the first section. As there are many magnetic core elements, each magnetic core element can be arranged to comprise stacked sheets for conducting the magnetic flux along the sheets.

Description

A stator module for an axial magnetic bearing
Field of the disclosure
The disclosure relates generally to magnetic levitation. More particularly, the 5 disclosure relates to a stator module suitable for operating as a part of an axial magnetic bearing. Furthermore, the disclosure relates to an axial magnetic bearing.
Background
Magnetic levitation systems, such as e.g. active magnetic bearings “AMB”, are commonly known in the art. Magnetic levitation systems are commonly utilized for 10 supporting a rotating or oscillating object. Using magnetic levitation in rotating machinery results in for example: reduction of friction, oil-free operation, lower maintenance costs, and/or higher reliability when compared to traditional rotating machines with mechanical bearings. An axial magnetic bearing comprises typically a rotor and a stator where the stator is configured to direct a controllable axial 15 magnetic force to the rotor. The stator comprises one or more stator modules each comprising a coil for generating a magnetic flux and a magnetic core element for constituting a magnetic circuit for the magnetic flux together with the rotor and with the air-gaps between the magnetic core element and the rotor. In a case where the stator comprises two stator modules of the kind mentioned above, the stator 20 modules are typically arranged so that the axial magnetic forces directed by the stator modules to the rotor are opposite to each other. In a case where the stator comprises only one stator module of the kind mentioned above, the axial magnetic bearing may comprise for example a permanent magnet system for directing an axial magnetic force to the rotor so that the axial magnetic force directed to the rotor 25 by the permanent magnet system is opposite to the axial magnetic force directed to the rotor by the stator module.
An axial magnetic bearing of the kind described above is however not free from challenges. One of the challenges is related to the magnetic core element which is usually a rotationally symmetric element that comprises an annular groove for the 30 coil of the axial magnetic bearing. Typically, the magnetic core element is made of
20165629 prh 28 -02- 2020 solid steel because it is challenging to construct a laminated structure, i.e. a stacked sheet structure, so that the magnetic flux is conducted along the sheets and not through the sheets. An inherent drawback of a magnetic core element made of solid steel is that a changing magnetic flux induces eddy currents which, in turn, tend to 5 suppress the changes of the magnetic flux. This phenomenon limits the operational bandwidth of the axial magnetic bearing. It is also possible that a magnetic core element is made of e.g. ferrite or other material that is electrically less conductive than solid steel but these materials are typically more expensive than steel. Furthermore, the relative magnetic permeability of these materials is typically 10 smaller than that of steel and thus there can be a need to increase the physical size of the magnetic core element and thereby also the physical size of the axial magnetic bearing. The increased physical size may complicate e.g. the integration of the axial magnetic bearing with radial magnetic bearings. Furthermore, in some cases, a magnetic core element made of material whose relative magnetic 15 permeability is smaller than that of steel may lead to a situation in which the axial magnetic bearing needs to be provided with permanent magnets that would not be needed if the magnetic core element were made of steel.
Summary
The following presents a simplified summary in order to provide a basic 20 understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the 25 invention.
In this document, the word “geometric” when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric line or axis, a geometric plane, a non-planar geometric surface, a geometric room, or any other geometric entity that is one, two, 30 or three dimensional.
20165629 prh 28 -02- 2020
In accordance with the invention, there is provided a new stator module suitable for operating as a part of an axial magnetic bearing. A stator module according to the invention comprises:
- a coil for conducting electric current so as to generate a magnetic flux, the coil comprising coil turns surrounding a rotor of the axial magnetic bearing so as to generate a substantially circumferential current density, and
- a magnetic core structure for constituting a magnetic circuit for the magnetic flux together with the rotor of the axial magnetic bearing and with air-gaps between the magnetic core structure and the rotor.
The magnetic core structure comprises a plurality of magnetic core elements supported by a frame structure of the stator module. Each of the magnetic core elements comprises a first section for conducting a part of the magnetic flux to the rotor, a second section for conducting the part of the magnetic flux from the rotor, and a third section for conducting the part of the magnetic flux from the second 15 section to the first section. Each of the magnetic core elements constitutes a substantially circumferential groove for a part of the coil and each of the magnetic core elements is arranged to comprise stacked sheets for conducting the appropriate part of the magnetic flux along the sheets. The sheets are made of ferromagnetic material and there are layers of electrical insulator between the 20 sheets. The use of the laminated structure, i.e. the stacked sheets, is facilitated by that fact that there are many magnetic core elements instead of a single ring-shaped magnetic core element. The sheets are stacked in a substantially circumferential direction, and each of the sheets is substantially planar and U-shaped so that the sheet comprises a first part constituting a part of the first section of the magnetic 25 core element, a second part constituting a part of the second section of the magnetic core element, and a third part constituting a part of the third section of the magnetic core element, wherein the first and second sections of the magnetic core elements have curved shapes so that, when the stator module is seen along an axial direction of the axial magnetic bearing, circumferential outlines of air-gap surfaces of the 30 magnetic core structure are arches whose center of curvature coincides with a geometric rotational axis of the rotor.
20165629 prh 28 -02- 2020
In accordance with the invention, there is provided also a new axial magnetic bearing that comprises:
- a rotor,
- at least one stator module according to the invention for directing an axial magnetic force to the rotor,
- equipment for generating a position signal indicative of an axial position of the rotor, and
- a controller for receiving the position signal and for controlling electric current of the coil of the stator module on the basis of a deviation of the axial position of the rotor from a reference axial position.
The axial magnetic bearing may comprise two stator modules for directing mutually opposite axial magnetic forces to the rotor. However, it is worth noting that the axial magnetic bearing may comprise only one stator module for supporting the rotor module against axial loading having a constant direction, e.g. against downwards 15 directed loading including the gravity force. It is also possible that the axial magnetic bearing comprises, in addition to the stator module, one or more permanent magnets so that the stator module and the one or more permanent magnets are arranged to direct mutually opposite axial magnetic forces to the rotor.
A number of exemplifying and non-limiting embodiments of the invention are 20 described in accompanied dependent claims.
Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and non-limiting embodiments when read in connection with the 25 accompanying drawings.
The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of un-recited features. The features recited in dependent claims are mutually freely combinable unless
20165629 prh 28 -02- 2020 otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.
Brief description of the figures
Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which:
figures 1a and 1b illustrate a stator module according to an exemplifying and nonlimiting embodiment of the invention, figures 2a and 2b illustrate an exemplifying stator module, figures 3a and 3b illustrate an exemplifying stator module, figure 4 illustrates an axial magnetic bearing according to an exemplifying and nonlimiting embodiment of the invention, and figure 5 shows a perspective view of a stator module according to an exemplifying and non-limiting embodiment of the invention.
Description of exemplifying and non-limiting embodiments
The specific examples provided in the description given below should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated.
Figures 1a and 1b illustrate a stator module according to an exemplifying and nonlimiting embodiment of the invention. The stator module is suitable for operating as a part of an axial magnetic bearing. Figure 1a shows a front view of the stator module so that the viewing direction is parallel with the geometric rotational axis 118 of a rotor 117 of the axial magnetic bearing. The geometric rotational axis 118 is parallel with the z-axis of a coordinate system 190. The rotor 117 can be for example a part of a rotor of a turbo electric machine such as e.g. a turbo generator or a turbo compressor. Figure 1 b shows a section view of the stator module so that the section
20165629 prh 28 -02- 2020 is taken along a line A-A shown in figure 1a and the section plane is parallel with the xz-plane of the coordinate system 190. The stator module comprises an annular coil 101 for conducting electric current so as to generate a magnetic flux. The conductor turns of the coil 101 are arranged to surround the rotor 117 so as to generate a circumferential current density. In figure 1 b, exemplifying flux lines of the magnetic flux are depicted with dashed lines 127 and 128. The stator module comprises a magnetic core structure 102. As illustrated in figure 1b, the magnetic core structure 102, the rotor 117, and the air-gaps between the magnetic core structure and the rotor constitute a magnetic circuit for the magnetic flux so that an axial magnetic 10 force is directed to the rotor 117.
The magnetic core structure 102 comprises magnetic core elements 103, 104, 105, 106, 107, 108, 109, and 110 which are mechanically supported by a frame structure 111 of the stator module. As shown in figure 1 a, the magnetic core elements 103110 are placed equidistantly on a circumference of a geometric circle. Each of the 15 magnetic core elements 103-110 constitutes a groove for a part of the coil as illustrated in figures 1a and 1b. Each of the magnetic core elements 103-110 comprises a first section for conducting a part of the magnetic flux to the rotor, a second section for conducting the part of the magnetic flux from the rotor, and a third section for conducting the part of the magnetic flux from the second section to 20 the first section. In figure 1b, the first section of the magnetic core element 103 is denoted with a reference 112, the second section of the magnetic core element 103 is denoted with a reference 113, and the third section of the magnetic core element 103 is denoted with a reference 114. As illustrated in figures 1 a and 1 b, the magnetic core elements 103-110 comprise stacked sheets for conducting the magnetic flux 25 along the sheets. In this exemplifying stator module, the sheets are stacked in a substantially circumferential direction as illustrated in figure 1a. For example, the sheets of the magnetic core elements 103 and 107 are stacked in the y-direction of the coordinate system 190, and the sheets of the magnetic core elements 105 and 109 are stacked in the x-direction of the coordinate system 190. As illustrated in 30 figure 1 b, each of the sheets is substantially planar and U-shaped so that the sheet comprises a first part constituting a part of the first section 112 of the magnetic core element, a second part constituting a part of the second section 113 of the magnetic
20165629 prh 28 -02- 2020 core element, and a third part constituting a part of the third section 114 of the magnetic core element. In this exemplifying stator module, the first and second sections of each magnetic core element protrude, in the axial direction of the axial magnetic bearing, from the third section of the magnetic core element. It is also possible that the first and/or second sections are not axial for example in cases where there is a need to arrange more room for the coil of the stator module.
In the exemplifying stator module illustrated in figures 1 a and 1 b, the first and second sections of the magnetic core elements 103-110 are curved so that, when the stator module is seen in the axial direction corresponding to figure 1a, circumferential outlines of the air-gap surfaces of the magnetic core structure are arches of a geometric circle whose center coincides with the geometric rotational axis 118 of the rotor. In figure 1a, two of the air-gap surfaces of the magnetic core structure 102 are denoted with references 115 and 116.
Figures 2a and 2b illustrate an exemplifying stator module. The stator module is suitable for operating as a part of an axial magnetic bearing. Figure 2a shows a front view of the stator module so that the viewing direction is parallel with the geometric rotational axis 218 of a rotor 217 of the axial magnetic bearing. The geometric rotational axis 218 is parallel with the z-axis of a coordinate system 290. Figure 2b shows a view of a section taken along a line A-A shown in figure 2a. The section plane is parallel with the xz-plane of the coordinate system 290. The stator module comprises a coil 201 for conducting electric current so as to generate a magnetic flux. The conductor turns of the coil 201 are arranged to surround the rotor 217 so as to generate a circumferential current density. The stator module comprises a magnetic core structure 202. In the same way as illustrated in figure 1b, the magnetic core structure 202, the rotor 217, and the air-gaps between the magnetic core structure and the rotor constitute a magnetic circuit for the magnetic flux so that an axial magnetic force is directed to the rotor 217.
The magnetic core structure 202 comprises magnetic core elements 203, 204, 205, 206, 207, 208, 209, and 210 which are mechanically supported by a frame structure 211 of the stator module. Each of the magnetic core elements 203-210 constitutes a groove for a part of the coil 201 as illustrated in figures 2a and 2b. Each of the
20165629 prh 28 -02- 2020 magnetic core elements 203-210 comprises a first section for conducting a part of the magnetic flux to the rotor, a second section for conducting the part of the magnetic flux from the rotor, and a third section for conducting the part of the magnetic flux from the second section to the first section. In figure 2b, the first 5 section of the magnetic core element 203 is denoted with a reference 212, the second section of the magnetic core element 203 is denoted with a reference 213, and the third section of the magnetic core element 203 is denoted with a reference 214. The magnetic core elements 203-210 comprise stacked sheets for conducting the magnetic flux along the sheets. In this exemplifying stator module, each sheet 10 is bent so that the sheet comprises a first part constituting a part of the first section of the magnetic core element under consideration, a second part constituting a part of the second section of the magnetic core element, and a third part constituting a part of the third section of the magnetic core element. Thus, in this exemplifying case, the sheets are bent to be substantially U-shaped as illustrated in figure 2b. In 15 this exemplifying stator module, the first and second sections of each magnetic core element protrude, in the axial direction of the axial magnetic bearing, from the third section of the magnetic core element. It is also possible that the first and/or second sections are not axial for example in cases where there is a need to arrange more room for the coil of the stator module.
Figures 3a and 3b illustrate an exemplifying stator module. The stator module is suitable for operating as a part of an axial magnetic bearing. Figure 3a shows a front view of the stator module so that the viewing direction is parallel with the geometric rotational axis 318 of a rotor 317 of the axial magnetic bearing. The geometric rotational axis 318 is parallel with the z-axis of a coordinate system 390. Figure 3b 25 shows a view of a section taken along a line A-A shown in figure 3a. The section plane is parallel with the xz-plane of the coordinate system 390. The stator module comprises coils for conducting electric currents each of which generates a part of the total magnetic flux flowing through the rotor 317. In figure 3a, five of the coils are denoted with references 301a, 301b, 301c, 301 d, and 301 e. The stator module 30 comprises a magnetic core structure 302. As illustrated in figure 3b, the magnetic core structure 302, the rotor 317, and the air-gaps between the magnetic core structure and the rotor constitute a magnetic circuit for the magnetic flux so that an
20165629 prh 28 -02- 2020 axial magnetic force is directed to the rotor 317. In figure 3b, an exemplifying flux line of the magnetic flux is depicted with a dashed line 327.
The magnetic core structure 302 comprises magnetic core elements which are mechanically supported by a frame structure 311 of the stator module. In figure 3a, 5 four of the magnetic core elements are denoted with references 303, 304, 305, and
306. Each of the magnetic core elements constitutes a substantially radial groove for two of the coils. For example, the magnetic core element 304 constitutes a substantially radial groove for the coils 301c and 301 d. Each of the magnetic core elements comprises a first section for conducting a part of the magnetic flux to the 10 rotor, a second section for conducting the part of the magnetic flux from the rotor, and a third section for conducting the part of the magnetic flux from the second section to the first section. In figure 3b, the first section of the magnetic core element 304 is denoted with a reference 312, the second section of the magnetic core element 304 is denoted with a reference 313, and the third section of the magnetic 15 core element 304 is denoted with a reference 314. As illustrated in figures 3a and
3b, the magnetic core elements comprise stacked sheets for conducting the magnetic flux along the sheets. In this exemplifying stator module, the sheets of each magnetic core element are stacked in a substantially radial direction as illustrated in figure 3a. For example, the sheets of the magnetic core element 304 20 are stacked in the y-direction of the coordinate system 390, and the sheets of the magnetic core element 306 are stacked in the x-direction of the coordinate system 390. As illustrated in figure 3b, each of the sheets is substantially planar and IIshaped so that the sheet comprises a first part constituting a part of the first section 312 of the magnetic core element, a second part constituting a part of the second 25 section 313 of the magnetic core element, and a third part constituting a part of the third section 314 of the magnetic core element.
Figure 4 illustrates an axial magnetic bearing according to an exemplifying and nonlimiting embodiment of the invention. The axial direction is the z-direction of a coordinate system 490. The axial magnetic bearing comprises a rotor 417 that 30 comprises a disc 418. The rotor can be for example a rotor of an electric machine where the axis of rotation is parallel with the z-axis of the coordinate system 490.
The axial magnetic bearing comprises equipment for generating a position signal Pz
20165629 prh 28 -02- 2020 indicative of the axial position of the rotor module. In the exemplifying case illustrated in figure 4, the equipment for generating the position signal Pz comprises a sensor 421 and a circuitry 422 for generating the position signal on the basis of the output signal of the sensor. The sensor 421 can be, for example but not 5 necessarily, an inductive sensor where the inductance is dependent on the distance from the sensor 421 to a conical surface of the rotor, and the circuitry 422 can be configured to form the position signal Pz on the basis of the inductance. The equipment for generating the position signal Pz comprises advantageously also another sensor facing towards another conical surface of the rotor, where the other 10 conical surface tapers in the negative z-direction of the coordinate system 490. In this exemplifying case, the circuitry 422 can be configured to form the position signal Pz on the basis of the difference between the inductances of the sensors. The other sensor and the other conical surface of the rotor are not shown in figure 4.
The axial magnetic bearing comprises stator modules 419 and 420 according to an 15 exemplifying embodiment of the invention. The stator modules 419 and 420 are arranged to direct mutually opposite axial magnetic forces to the disc 418 of the rotor 417. In figure 4, the stator modules 419 and 420 are shown as section views where the section plane is parallel with the xz-plane of the coordinate system 490. Exemplifying flux lines of the magnetic fluxes generated by the stator modules are 20 depicted with dashed lines in figure 4. The axial magnetic bearing comprises a controller 426 for receiving the position signal Pz and for controlling electric currents of the stator modules 419 and 420 on the basis of a deviation of the axial position of the rotor 417 from the reference axial position. The controller 426 comprises a control section 425 and controllable output stages 423 and 424 for supplying electric 25 currents to the coils of the stator modules 419 and 420. The control section 425 is configured to control the output stages 423 and 424 so that the position signal Pz is driven to the reference value of the position signal. The control section 425 can be implemented with one or more analogue circuits and/or with one or more digital circuits each of which can be a programmable processor circuit provided with 30 appropriate software, a dedicated hardware processor such as for example an application specific integrated circuit “ASIC”, or a configurable hardware processor such as, for example, a field programmable gate array “FPGA”.
Figure 5 shows a perspective view of a stator module 550 that is suitable for operating as a part of an axial magnetic bearing. The coil of the stator module 550 is not shown in figure 5. Figure 5 does not depict how the magnetic core elements of the stator module 550 are composed of stacked sheets. The magnetic core 5 elements can be composed of stacked sheets for example in the same way as the magnetic core elements 103-110 shown in figure 1a are composed of stacked sheets.
The specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims. Lists 10 and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.

Claims (5)

PatenttivaatimuksetThe claims 1. Staattorimoduuli aksiaalista magneettilaakeria varten, jolloin staattorimoduuli käsittääA stator module for an axial magnetic bearing, the stator module comprising - kelan (101) sähkövirran johtamiseksi magneettivuon generoimiseksi, joka- a coil (101) for conducting an electric current to generate a magnetic flux, which 5 kela käsittää käämikierroksia aksiaalisen magneettilaakerin roottorin ympärillä olennaisesti kehäsuuntaisen virrantiheyden generoimiseksi, ja5 the coil comprises winding turns around the rotor of the axial magnetic bearing to generate a substantially circumferential current density, and - magneettisydänrakenteen (102) magneettipiirin magneettivuota varten muodostamiseksi yhdessä aksiaalisen magneettilaakerin roottorin ja magneettisydänrakenteen ja roottorin välisten ilmarakojen kanssa,- a magnetic core structure (102) for forming a magnetic circuit for magnetic flux together with the air gaps between the rotor of the axial magnetic bearing and the magnetic core structure and the rotor, 10 joka magneettisydänrakenne käsittää joukon magneettisydänelementtejä (103 110) staattohmoduulin runkorakenteeseen (111) tuettuina, missä kukin magneettisydänelementeistä käsittää ensimmäisen osion (112) osan magneettivuosta johtamiseksi roottoriin ja toisen osion (113) osan magneettivuosta johtamiseksi pois roottorista ja kolmannen osion (114) osan magneettivuosta10, the magnetic core structure comprising a plurality of magnetic core elements (103 110) supported on the statomhmode module body structure (111), each of the magnetic core elements comprising a first section (112) for conducting a portion of magnetic flux to the rotor and a second portion (113) for discharging a portion of magnetic flux 15 johtamiseksi toisesta osiosta ensimmäiseen osioon, jolloin kukin magneettisydänelementeistä muodostaa olennaisesti kehäsuuntaisen uran kelan osaa varten, ja kukin magneettisydänelementeistä käsittää pinottuja levyjä osan magneettivuosta johtamiseksi levyjä pitkin, jotka levyt on pinottu olennaisesti kehäsuunnassa, ja kukin levyistä on olennaisesti tasomainen ja U:n muotoinen niin,15 from the second section to the first section, each of the magnetic core elements forming a substantially circumferential groove for the coil portion, and each of the magnetic core elements comprising stacked plates for conducting a portion of the magnetic flux along the plates, the plates being stacked substantially circumferentially; 20 että levy käsittää ensimmäisen osan, joka muodostaa osan magneettisydänelementin ensimmäisestä osiosta (112), toisen osan, joka muodostaa osan magneettisydänelementin toisesta osiosta (113), ja kolmannen osan, joka muodostaa osan magneettisydänelementin kolmannesta osiosta (114), tunnettu siitä, että magneettisydänelementtien (112, 113) ensimmäisellä tai toisella20 that the plate comprises a first part forming part of the first part (112) of the magnetic core element, a second part forming part of the second part (113) of the magnetic core element, and a third part forming part of the third part (114) of the magnetic core element, characterized in that the magnetic core elements (114) 112, 113) on the first or second 25 osiolla on kaarevat muodot niin, että katsottaessa staattorimoduulia aksiaalisen magneettilaakerin aksiaalisessa suunnassa magneettisydänrakenteen ilmarakopintojen (115, 116) kehä-ääriviivat ovat kaaria, joiden kaarevuuskeskipiste osuu yhteen roottorin geometrisen pyöhntäakselin kanssa.The section 25 has curved shapes so that when the stator module is viewed in the axial direction of the axial magnetic bearing, the circumferential contours of the air core surfaces (115, 116) of the magnetic core structure are arcs whose center of curvature coincides with the geometric rotational axis of the rotor. 2. Patenttivaatimuksen 1 mukainen staattorimoduuli, jossa 30 magneettisydänelementin ensimmäiset ja toiset osiot (112, 113) ulkonevat aksiaalisen magneettilaakerin aksiaalisessa suunnassa magneettisydänelementin kolmannesta osiosta.The stator module of claim 1, wherein the first and second portions (112, 113) of the magnetic core element 30 project from the third portion of the magnetic core element in the axial direction of the axial magnetic bearing. 3. Patenttivaatimuksen 1 tai 2 mukainen staattorimoduuli, jossa magneettisydänelementit on sijoitettu geometrisen ympyrän kehälle tasavälisesti.A stator module according to claim 1 or 2, wherein the magnetic core elements are evenly spaced on the circumference of the geometric circle. 55 4. Aksiaalinen magneettilaakeh, joka käsittää4. An axial magnetic bearing comprising - roottorin (417),- rotor (417), - jonkin patenttivaatimuksista 1 - 3 mukaisen ainakin yhden staattohmoduulin (419) aksiaalisen magneettivoiman suuntaamiseksi roottoriin,- at least one static ohm module (419) according to any one of claims 1 to 3 for applying an axial magnetic force to the rotor, - välineet (421,422) roottorin aksiaalisen asennon osoittavan asentosignaalin- means (421,422) for a position signal indicating the axial position of the rotor 10 generoimiseksi,10 to generate, - ohjaimen (426) asentosignaalin vastaanottamiseksi ja staattohmoduulin kelan sähkövirran ohjaamiseksi roottorin aksiaalisen asennon poikkeaman aksiaalisesta referenssiasennosta perusteella.- a controller (426) for receiving a position signal and for controlling the electric current of the coil of the static module based on the deviation of the axial position of the rotor from the axial reference position. 5. Patenttivaatimuksen 4 mukainen aksiaalinen magneettilaakeh, joka käsittää 15 toisen staattohmoduulin (420) toisen aksiaalisen magneettivoiman suuntaamiseksi roottoriin ja jossa ohjain on konfiguroitu ohjaamaan toisen staattohmoduulin kelan sähkövirtaa aksiaalisen asennon poikkeaman aksiaalisesta referenssiasennosta perusteella, staattorimoduulien roottoriin suuntaamien aksiaalisten magneettivoimien ollessa vastakkaiset toisiinsa nähden.The axial magnetic bearing of claim 4, comprising a second static ohm module (420) for applying a second axial magnetic force to the rotor, and wherein the controller is configured to control the electric current of the second static module module coil based on the axial position deviation
FI20165629A 2016-08-24 2016-08-24 A stator module for an axial magnetic bearing FI128371B (en)

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CN108880154A (en) * 2018-07-31 2018-11-23 江苏大学 A kind of magnetic suspension switched reluctance motor
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EP3789624B1 (en) * 2019-09-05 2023-06-28 Mecos AG Magnetic bearing device having a toroidal design
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JP2008236925A (en) * 2007-03-22 2008-10-02 Jtekt Corp Electromagnet for axial magneto bearing and magneto bearing device
US8963393B2 (en) * 2012-12-18 2015-02-24 Abb Research Ltd. Magnetic thrust bearings

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