WO2021064621A1 - Construction method for winding core for electric motor - Google Patents

Construction method for winding core for electric motor Download PDF

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Publication number
WO2021064621A1
WO2021064621A1 PCT/IB2020/059189 IB2020059189W WO2021064621A1 WO 2021064621 A1 WO2021064621 A1 WO 2021064621A1 IB 2020059189 W IB2020059189 W IB 2020059189W WO 2021064621 A1 WO2021064621 A1 WO 2021064621A1
Authority
WO
WIPO (PCT)
Prior art keywords
central part
core
inductor
sheets
coil according
Prior art date
Application number
PCT/IB2020/059189
Other languages
French (fr)
Inventor
Bruno Vianello
Original Assignee
Texa Dynamics S.R.L.
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 Texa Dynamics S.R.L. filed Critical Texa Dynamics S.R.L.
Publication of WO2021064621A1 publication Critical patent/WO2021064621A1/en

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Classifications

    • 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
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H01F27/245—Magnetic cores made from sheets, e.g. grain-oriented
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H01F27/255—Magnetic cores made from particles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0206—Manufacturing of magnetic cores by mechanical means
    • H01F41/0233—Manufacturing of magnetic circuits made from sheets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0206—Manufacturing of magnetic cores by mechanical means
    • H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder
    • 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

Definitions

  • the present invention refers to a method to make a core about which an electric winding mounted in an electric motor is placed.
  • the present invention also refers to the core and the inductor thus obtained, and to the motor comprising the core.
  • the invention refers preferably to an axial-flux electric motor, a case in which it has been demonstrated particularly effective.
  • Axial-flux electric motors have windings that each generate a magnetic flux with polar axis parallel to the rotor’s rotation axis. While US5861695 and US6255005 show examples of inductors, currently the state of the art for axial flux machine cores involves the use of sintered soft magnetic material (Soft Magnetic Composite) which, however, has performance limits in terms of magnetic permeability.
  • Soft Magnetic Composite sintered soft magnetic material
  • the magnetic properties (permeability and loss figure) of SMC are not optimal, but it is chosen anyway because of the need to make complex shaped cores.
  • the main object of the invention is to improve the present state of the art. This is achieved by a method according to the attached claims; other advantageous technical characteristics are defined in the dependent claims.
  • a method is then presented to make a core around which an electric winding can be arranged to create a magnetic field generator, with the steps of making a central part of the core made with superimposed sheets of ferromagnetic material (e.g. iron...), surrounding the central part with powdered SMC material and then sintering it to obtain a solid composite core.
  • ferromagnetic material e.g. iron
  • the method it is possible to produce a composite core that combines the superior magnetic properties (permeability and loss figure) of a laminated ferromagnetic material and the design freedom in creating an overall core having complex geometries determined by the outer shell of SMC.
  • the SMC material is shaped, for example in a mold.
  • the method envisages placing the central part in the mould and then adding inside the mould the SMC material in powder form or granules. Then by sintering, i.e. a high-temperature heat treatment that, for example, can take place in said mould, the SMC material is transformed into an indivisible, solid material.
  • the composite core also ensures electrical insulation and is easily shaped to optimize the coupling with the winding surrounding it.
  • the sintered material can take a shape that maximizes the torque density of the entire machine; moreover, it makes no longer necessary the use of a polymeric body to safeguard the integrity of the conductors’ insulation.
  • the composite core has mechanical and above all magnetic characteristics that are overall superior to a core made only of SMC or laminated ferromagnetic material.
  • Another aspect of the invention concerns an inductor or coil to generate an electric field that comprises a core and an electric winding wound around the core, wherein the core is composite and formed by a central part of the core made of superimposed sheets of ferromagnetic material (e.g. iron%), and an outer shell surrounding the central part made of sintered SMC material.
  • ferromagnetic material e.g. iron
  • Said central part may be composed by the superposition of sheets being all equal and/or with the same plan, or it may derive from the juxtaposition of a plurality of stacks of equal or different sheets.
  • the outer shell may surround the central part completely, i.e. three-dimensionally, or it may surround it only partially, in which case preferably the shell is a ring that wraps the central part leaving two ends thereof uncovered.
  • usable SMC material sintered material consisting of iron powders coated with insulating resins, in different proportions and of different nature; allows the substantial reduction of electrical conductivity and the making of three- dimensional geometries and fluxes, e.g. Somaloy®.
  • usable ferromagnetic material soft ferromagnetic material bound to various elements (Si, etc.), to improve magnetic permeability and electrical resistivity properties, and/or laminated material to reduce the possible path of eddy currents.
  • the different layers are glued to form a compact structure.
  • FIG. 1 Another aspect of the invention concerns a stator of an axial flux electric motor comprising a constant angular pitch circular series of inductors or coils, made as defined above, to each generate a magnetic field.
  • the stator is equipped with windings arranged in a circular series about a rotation axis of a rotor. Each winding acts to create a magnetic field, with a polar axis parallel to the rotation axis, through which a rotor is set into rotation thanks to the magnetic interaction between the generated magnetic fields and a corresponding circular series of magnetic elements of the rotor.
  • This type of motor has a more complex structure than radial flux motors but is lighter and smaller the power being the same.
  • FIG. 1 shows a three-dimensional view of a core
  • FIG. 2 shows a three-dimensional view of a variant of core.
  • the construction steps of a core for the stator of an axial flux electric motor will be now described.
  • multiple or repeated parts are not all indicated with numbers. Equal numbers indicate equal parts.
  • a core MC (fig. 1) is substantially wedge-shaped, to be arranged in a circular series.
  • the core MC has a top face 50, a base face 52 and a side surface 54 (these relative spatial terms are used only for ease of description).
  • the top face 50 and base face 52 are orthogonal to an imaginary axis Y, here indicated as the polar axis of the magnetic field that will pass through the core MC.
  • the volume of the core MC consists of a central part 10 and an outer shell 30 that incorporates the central part 10.
  • the central part 10 is formed by superimposed sheets 12 of ferromagnetic material, wherein the sheets 12 lie on a plane parallel to the Y axis. In the shown example there is a pack of sheets 12 all the same and stacked to form a parallelepiped of sheets 12.
  • the outer shell 30 is made instead of sintered SMC material, and surrounds the central part 10 forming a sort of ring coaxial to the Y axis. Short sides of the sheets 12 may remain visible on the top face 50 and the base face 52, but not necessarily.
  • a second core MC2 (fig. 2) is substantially wedge-shaped, to be arranged in a circular series.
  • the core MC2 still has a top face 50, a base face 52 and a side surface 54 (these relative spatial terms are used only for ease of description).
  • the volume of the core MC2 is still composed of a central part 70 and an outer shell 80.
  • the central part 70 is formed by two groups of superimposed sheets 14, 16 of ferromagnetic material, wherein the sheets 14, 16 lie on a plane parallel to the axis Y and the sheets 14, 16 of each group are equal to each other.
  • the sheets 14 are wider than the sheets 16.
  • the outer shell 70 is made like the shell 30.
  • Number and thickness of the sheets may vary from what is shown, the same applies for the number of attached groups of sheets of different sizes.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Iron Core Of Rotating Electric Machines (AREA)

Abstract

A method is described for making a core (MC) around which an electrical winding can be arranged to create a magnetic field generator, with the steps of making a central part (10) of the core with superimposed sheets of ferromagnetic material (12), surrounding the central part (10) with powder SMC material (30) and then sintering it to obtain a solid composite core.

Description

Construction Method For Winding Core For Electric Motor
The present invention refers to a method to make a core about which an electric winding mounted in an electric motor is placed. The present invention also refers to the core and the inductor thus obtained, and to the motor comprising the core. The invention refers preferably to an axial-flux electric motor, a case in which it has been demonstrated particularly effective.
Axial-flux electric motors have windings that each generate a magnetic flux with polar axis parallel to the rotor’s rotation axis. While US5861695 and US6255005 show examples of inductors, currently the state of the art for axial flux machine cores involves the use of sintered soft magnetic material (Soft Magnetic Composite) which, however, has performance limits in terms of magnetic permeability.
The magnetic properties (permeability and loss figure) of SMC are not optimal, but it is chosen anyway because of the need to make complex shaped cores.
A core of improved performance would then be needed.
The main object of the invention is to improve the present state of the art. This is achieved by a method according to the attached claims; other advantageous technical characteristics are defined in the dependent claims. A method is then presented to make a core around which an electric winding can be arranged to create a magnetic field generator, with the steps of making a central part of the core made with superimposed sheets of ferromagnetic material (e.g. iron...), surrounding the central part with powdered SMC material and then sintering it to obtain a solid composite core.
With the method it is possible to produce a composite core that combines the superior magnetic properties (permeability and loss figure) of a laminated ferromagnetic material and the design freedom in creating an overall core having complex geometries determined by the outer shell of SMC. The SMC material is shaped, for example in a mold. In particular, the method envisages placing the central part in the mould and then adding inside the mould the SMC material in powder form or granules. Then by sintering, i.e. a high-temperature heat treatment that, for example, can take place in said mould, the SMC material is transformed into an indivisible, solid material. The composite core also ensures electrical insulation and is easily shaped to optimize the coupling with the winding surrounding it.
Another advantage is that the sintered material can take a shape that maximizes the torque density of the entire machine; moreover, it makes no longer necessary the use of a polymeric body to safeguard the integrity of the conductors’ insulation.
In particular, the composite core has mechanical and above all magnetic characteristics that are overall superior to a core made only of SMC or laminated ferromagnetic material.
Another aspect of the invention concerns an inductor or coil to generate an electric field that comprises a core and an electric winding wound around the core, wherein the core is composite and formed by a central part of the core made of superimposed sheets of ferromagnetic material (e.g. iron...), and an outer shell surrounding the central part made of sintered SMC material.
Said central part may be composed by the superposition of sheets being all equal and/or with the same plan, or it may derive from the juxtaposition of a plurality of stacks of equal or different sheets. The outer shell may surround the central part completely, i.e. three-dimensionally, or it may surround it only partially, in which case preferably the shell is a ring that wraps the central part leaving two ends thereof uncovered.
As preferred examples of usable SMC material: sintered material consisting of iron powders coated with insulating resins, in different proportions and of different nature; allows the substantial reduction of electrical conductivity and the making of three- dimensional geometries and fluxes, e.g. Somaloy®.
As preferred examples of usable ferromagnetic material: soft ferromagnetic material bound to various elements (Si, etc.), to improve magnetic permeability and electrical resistivity properties, and/or laminated material to reduce the possible path of eddy currents. The different layers are glued to form a compact structure.
Another aspect of the invention concerns a stator of an axial flux electric motor comprising a constant angular pitch circular series of inductors or coils, made as defined above, to each generate a magnetic field. In an axial flux electric motor the stator is equipped with windings arranged in a circular series about a rotation axis of a rotor. Each winding acts to create a magnetic field, with a polar axis parallel to the rotation axis, through which a rotor is set into rotation thanks to the magnetic interaction between the generated magnetic fields and a corresponding circular series of magnetic elements of the rotor. This type of motor has a more complex structure than radial flux motors but is lighter and smaller the power being the same.
Further advantages will be clear from the following description, which refers to an example of a preferred core construction wherein:
- Figure 1 shows a three-dimensional view of a core,
- Figure 2 shows a three-dimensional view of a variant of core. The construction steps of a core for the stator of an axial flux electric motor will be now described. In order not to crowd the drawings multiple or repeated parts are not all indicated with numbers. Equal numbers indicate equal parts.
A core MC (fig. 1) is substantially wedge-shaped, to be arranged in a circular series. The core MC has a top face 50, a base face 52 and a side surface 54 (these relative spatial terms are used only for ease of description). The top face 50 and base face 52 are orthogonal to an imaginary axis Y, here indicated as the polar axis of the magnetic field that will pass through the core MC.
The volume of the core MC consists of a central part 10 and an outer shell 30 that incorporates the central part 10.
The central part 10 is formed by superimposed sheets 12 of ferromagnetic material, wherein the sheets 12 lie on a plane parallel to the Y axis. In the shown example there is a pack of sheets 12 all the same and stacked to form a parallelepiped of sheets 12.
The outer shell 30 is made instead of sintered SMC material, and surrounds the central part 10 forming a sort of ring coaxial to the Y axis. Short sides of the sheets 12 may remain visible on the top face 50 and the base face 52, but not necessarily.
An electrical winding (not shown) is wound around the side face 54 of the core MC, spiraling around the axis Y. By powering the winding, a magnetic field is created - as known. A second core MC2 (fig. 2) is substantially wedge-shaped, to be arranged in a circular series.
The core MC2 still has a top face 50, a base face 52 and a side surface 54 (these relative spatial terms are used only for ease of description).
The volume of the core MC2 is still composed of a central part 70 and an outer shell 80. This time the central part 70 is formed by two groups of superimposed sheets 14, 16 of ferromagnetic material, wherein the sheets 14, 16 lie on a plane parallel to the axis Y and the sheets 14, 16 of each group are equal to each other. In the example shown there is a pack of sheets 14 attached to a pack of sheets 16 to occupy or fill a larger internal volume of the shell 70 otherwise not achievable with a single pack. In the example shown, the sheets 14 are wider than the sheets 16.
The outer shell 70 is made like the shell 30.
Number and thickness of the sheets may vary from what is shown, the same applies for the number of attached groups of sheets of different sizes.

Claims

1. Method for making a core (MC) around which an electrical winding can be arranged to create a magnetic field generator, with the steps of making a central part (10) of the core with superimposed sheets of ferromagnetic material (12), surrounding the central part (10) with powder SMC material (30) and then sintering it to obtain a solid composite core.
2. Inductor or coil for generating an electric field comprising a core (MC) and an electric winding wound around the core, wherein the core is composite and formed by a central part (10) made of superimposed sheets of ferromagnetic material (12), and an outer shell (30), surrounding the central part (10), made of sintered SMC material.
3. Inductor or coil according to claim 2, wherein the central part (10) is composed of the superposition of sheets, all the same and/or with the same plan geometry.
4. Inductor or coil according to claim 2, wherein the central part (10) is composed by the juxtaposition of a plurality of identical or different packs of sheets.
5. Inductor or coil according to claim 2 or 3 or 4, wherein the outer shell surrounds the central part completely.
6. Inductor or coil according to claim 2 or 3 or 4, wherein the outer shell only partially surrounds the central part, the shell being a ring that wraps the central part leaving the two ends thereof uncovered.
7. Inductor or coil according to any of the previous claims, wherein the SMC material comprises a sintered material consisting of iron powders coated with insulating resins.
8. Stator of an axial-flow electric motor comprising a constant-angular-pitch circular series of inductors or coils made as in any of the previous claims, the inductors or coils being arranged to each generate a magnetic field with a polar axis parallel to that of the other inductors or coils.
PCT/IB2020/059189 2019-10-02 2020-10-01 Construction method for winding core for electric motor WO2021064621A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT102019000017759 2019-10-02
IT201900017759 2019-10-02

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WO2021064621A1 true WO2021064621A1 (en) 2021-04-08

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040119374A1 (en) * 2002-12-18 2004-06-24 Carl Ralph James Axial flux induction motor
US20140232507A1 (en) * 2011-10-03 2014-08-21 Panasonic Corporation Powder magnetic core and production method for same
CN207743770U (en) * 2017-12-01 2018-08-17 江西清能高科技术有限公司 A kind of aircraft electro-motor control SMC iron cores
CN209001686U (en) * 2018-08-31 2019-06-18 核心驱动科技（金华）有限公司 A kind of segment core and disc type electric machine

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040119374A1 (en) * 2002-12-18 2004-06-24 Carl Ralph James Axial flux induction motor
US20140232507A1 (en) * 2011-10-03 2014-08-21 Panasonic Corporation Powder magnetic core and production method for same
CN207743770U (en) * 2017-12-01 2018-08-17 江西清能高科技术有限公司 A kind of aircraft electro-motor control SMC iron cores
CN209001686U (en) * 2018-08-31 2019-06-18 核心驱动科技（金华）有限公司 A kind of segment core and disc type electric machine

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