WO2009063350A2 - Permanent magnet rotor for a synchronous electrical machine, particularly for a reluctance motor - Google Patents

Permanent magnet rotor for a synchronous electrical machine, particularly for a reluctance motor Download PDF

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Publication number
WO2009063350A2
WO2009063350A2 PCT/IB2008/054477 IB2008054477W WO2009063350A2 WO 2009063350 A2 WO2009063350 A2 WO 2009063350A2 IB 2008054477 W IB2008054477 W IB 2008054477W WO 2009063350 A2 WO2009063350 A2 WO 2009063350A2
Authority
WO
WIPO (PCT)
Prior art keywords
rotor
stack
plates
cavities
magnetic material
Prior art date
Application number
PCT/IB2008/054477
Other languages
French (fr)
Other versions
WO2009063350A3 (en
Inventor
Giovanni Baino
Andrea Carrer
Original Assignee
Askoll P & C 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 Askoll P & C S.R.L. filed Critical Askoll P & C S.R.L.
Publication of WO2009063350A2 publication Critical patent/WO2009063350A2/en
Publication of WO2009063350A3 publication Critical patent/WO2009063350A3/en

Links

Classifications

    • 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
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/27—Rotor cores with permanent magnets
    • H02K1/2706—Inner rotors
    • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
    • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
    • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
    • H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
    • 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
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/24—Rotor cores with salient poles ; Variable reluctance rotors
    • H02K1/246—Variable reluctance rotors

Definitions

  • Permanent magnet rotor for a synchronous electrical machine, particularly for a reluctance motor
  • the present invention relates to a rotor for a synchronous electrical machine, particularly for a reluctance motor, provided with permanent magnets.
  • the invention relates to a rotor with N poles, where N is an even integer, comprising a stack of plates of magnetic material, each having N adjacent angular sectors, in each of which is formed a corresponding plurality of cavities or apertures, into which there extend corresponding permanent magnetic elements which are magnetized in each sector in the opposite direction to those in the adjacent sectors.
  • such a rotor is made by inserting "solid" permanent magnets, for example permanent magnets made from neodymium, iron and boron, into the cavities of its angular sectors.
  • One object of the present invention is therefore to propose an alternative method of making a rotor for a synchronous electrical machine, particularly for a reluctance motor, which overcomes the aforementioned problems of the prior art.
  • a rotor of the type specified above characterized in that the aforesaid permanent magnetic elements are formed from a magnetic material which is injection moulded in the apertures or cavities of the stack of plates.
  • the solution according to the invention enables the permanent magnets to be formed in situ in the cavities in an extremely simple way, even in cases in which continuous or progressive skewing is present in the plates of the rotor stack.
  • the permanent magnetic elements can be overmoulded on the rotor plate stack in the presence of a magnetic field such that the magnetic domains of the permanent magnetic elements associated with each sector of the rotor can be orientated in the desired way.
  • the magnetic material can be moulded, by injection moulding for example, in the absence of magnetization in the mould, and the desired orientation of the domains can be obtained subsequently, outside the mould, using known types of magnetizing equipment.
  • the desired orientation of the domains of the moulded permanent magnetic elements can be obtained by applying a magnetic field in the mould during the injection moulding, and by then carrying out a further magnetization operation after moulding, in a known type of magnetizing equipment.
  • Figure 1 is a partial view in cross section of a four-pole rotor made according to the present invention.
  • Each of the angular sectors 1-4 has a corresponding plurality of cavities or apertures C capable of forming barriers to the flow of the magnetic flux in the rotor and having a generally curved shape, with the convexity of each curve facing the axis O of the rotor R.
  • each of the radially innermost cavities C is interrupted centrally by a corresponding radial link B for structural reinforcement.
  • the stack LS of plates L is subjected to a moulding operation, such as injection moulding, by means of which elements M of permanent magnetic material are formed in the apertures or cavities C.
  • the moulded magnetic material can be, for example, a plastic-ferrite, or a neodymium-iron-boron-based material in a plastic matrix.
  • the cavities C can if necessary be filled completely by the magnetic elements moulded in them.
  • the cavities C may be only partially filled with the injection moulded magnetic elements, as shown by way of example in Figure 1.
  • the domains of the injection moulded magnetic elements can be orientated within the mould and/or after moulding, in a known type of magnetizing equipment.
  • the injection moulded magnetic material can extend at least partially over the outer faces of the terminal plates of the rotor stack LS, in order to improve and reinforce the assembly of this stack, thus facilitating the moulding of the stack.
  • the overmoulded magnetic material can subsequently be removed locally in order to improve the balance of the rotor.
  • the magnetization of the permanent magnetic elements M is essentially orientated, in a known way, in a radial direction, the direction in each sector being opposite to the direction in the adjacent sectors, as shown in Figure 1 in which the letters N and S indicate the "north" and “south” poles, respectively, of the permanent magnetic elements M.
  • the rotor according to the invention is easy to produce, even if progressive or continuous skewing is present in the stack LS of plates L.
  • the invention makes it possible to save time in the manufacture of the rotor, and enables a plurality of rotors to be produced simultaneously by using multiple moulds.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Permanent Field Magnets Of Synchronous Machinery (AREA)
  • Iron Core Of Rotating Electric Machines (AREA)
  • Synchronous Machinery (AREA)

Abstract

The rotor has N poles, where N is an even number, and comprises a stack (LS) of plates (L) of magnetic material, each of which has N adjacent angular sectors (1-4), in each of which is formed a corresponding plurality of cavities or apertures (C) in which there extend corresponding permanent magnetic elements (M) which are magnetized in each sector (1-4) in the opposite direction to those of the adjacent sectors, and which are formed from a magnetic material moulded in the apertures or cavities (C) of the stack (LS) of plates (L).

Description

Permanent magnet rotor for a synchronous electrical machine, particularly for a reluctance motor
The present invention relates to a rotor for a synchronous electrical machine, particularly for a reluctance motor, provided with permanent magnets.
More specifically, the invention relates to a rotor with N poles, where N is an even integer, comprising a stack of plates of magnetic material, each having N adjacent angular sectors, in each of which is formed a corresponding plurality of cavities or apertures, into which there extend corresponding permanent magnetic elements which are magnetized in each sector in the opposite direction to those in the adjacent sectors.
A rotor of this type is described in US 5 818 140.
In the method used at present, such a rotor is made by inserting "solid" permanent magnets, for example permanent magnets made from neodymium, iron and boron, into the cavities of its angular sectors.
This solution requires the preliminary production of permanent magnets shaped so as to fit the shapes of the corresponding cavities of the rotor.
In practice, it is frequently useful or necessary for the cavities of the rotor to have a degree of inclination or "skewing".
The prior art, according to which permanent magnets are produced and inserted, does not facilitate the creation of a progressive "skewing" of the plates in the stack, but only allows skewing to be created between successive groups or sub-stacks of plates, thus giving rise to a considerable number of problems in respect of the shapes and/or number of the permanent magnets required for this purpose, and entailing significant expenditure.
One object of the present invention is therefore to propose an alternative method of making a rotor for a synchronous electrical machine, particularly for a reluctance motor, which overcomes the aforementioned problems of the prior art.
This and other objects are achieved according to the invention by means of a rotor of the type specified above, characterized in that the aforesaid permanent magnetic elements are formed from a magnetic material which is injection moulded in the apertures or cavities of the stack of plates.
The solution according to the invention enables the permanent magnets to be formed in situ in the cavities in an extremely simple way, even in cases in which continuous or progressive skewing is present in the plates of the rotor stack.
When the solution according to the invention is used, the permanent magnetic elements can be overmoulded on the rotor plate stack in the presence of a magnetic field such that the magnetic domains of the permanent magnetic elements associated with each sector of the rotor can be orientated in the desired way.
Alternatively, the magnetic material can be moulded, by injection moulding for example, in the absence of magnetization in the mould, and the desired orientation of the domains can be obtained subsequently, outside the mould, using known types of magnetizing equipment.
In an alternative method, the desired orientation of the domains of the moulded permanent magnetic elements can be obtained by applying a magnetic field in the mould during the injection moulding, and by then carrying out a further magnetization operation after moulding, in a known type of magnetizing equipment.
Other features and advantages of the invention will be made clear by the following detailed description, provided purely by way of non-limiting example, with reference to the appended drawing, in which Figure 1 is a partial view in cross section of a four-pole rotor made according to the present invention.
With reference to Figure 1, a rotor R with N=4 poles, for a synchronous electrical machine, particularly for a reluctance motor, comprises a stack LS of plates L of magnetic material, only one of which is visible in the drawing.
Each of the plates L of the stack LS has N=4 adjacent angular sectors, indicated by the numbers 1 to 4, ideally lying between two planes which intersect orthogonally on the axis O of the rotor, the orientations of these planes being shown by two broken lines identified as Ll and L2 in Figure 1.
Each of the angular sectors 1-4 has a corresponding plurality of cavities or apertures C capable of forming barriers to the flow of the magnetic flux in the rotor and having a generally curved shape, with the convexity of each curve facing the axis O of the rotor R. In the embodiment shown by way of example, each of the radially innermost cavities C is interrupted centrally by a corresponding radial link B for structural reinforcement.
In the embodiment, the stack LS of plates L is subjected to a moulding operation, such as injection moulding, by means of which elements M of permanent magnetic material are formed in the apertures or cavities C. The moulded magnetic material can be, for example, a plastic-ferrite, or a neodymium-iron-boron-based material in a plastic matrix.
If the material used is a plastic-ferrite or other material with a low specific magnetic energy, typically having a rather low magnetic induction, the cavities C can if necessary be filled completely by the magnetic elements moulded in them. In general, if materials with a high magnetic inductance, such as neodymium-iron-boron-based materials, are used, the cavities C may be only partially filled with the injection moulded magnetic elements, as shown by way of example in Figure 1.
As mentioned above, the domains of the injection moulded magnetic elements can be orientated within the mould and/or after moulding, in a known type of magnetizing equipment.
The injection moulded magnetic material can extend at least partially over the outer faces of the terminal plates of the rotor stack LS, in order to improve and reinforce the assembly of this stack, thus facilitating the moulding of the stack.
The overmoulded magnetic material can subsequently be removed locally in order to improve the balance of the rotor.
The magnetization of the permanent magnetic elements M is essentially orientated, in a known way, in a radial direction, the direction in each sector being opposite to the direction in the adjacent sectors, as shown in Figure 1 in which the letters N and S indicate the "north" and "south" poles, respectively, of the permanent magnetic elements M.
The rotor according to the invention is easy to produce, even if progressive or continuous skewing is present in the stack LS of plates L.
In practice, the invention makes it possible to save time in the manufacture of the rotor, and enables a plurality of rotors to be produced simultaneously by using multiple moulds.
Naturally, the principle of the invention remaining the same, the forms of embodiment and the details of construction may be varied widely with respect to those described and illustrated, which have been given purely by way of non- limiting example, without thereby departing from the scope of the invention as defined by the attached claims.

Claims

1. Rotor with N poles, where N is an even number, for a synchronous electrical machine, particularly for a reluctance motor, comprising a stack (LS) of plates (L) of magnetic material, each of which has N adjacent angular sectors (1-4), in each of which is formed a corresponding plurality of cavities or apertures (C) in which there extend corresponding permanent magnetic elements (M) which are magnetized in each sector (1- 4) in the opposite direction to those of the adjacent sectors; the rotor (R) being characterized in that said permanent magnetic elements (M) are formed from a magnetic material moulded in said apertures or cavities (C) of the stack (LS) of plates (L).
2. Rotor according to Claim 1, in which said magnetic material is injection moulded in said apertures or cavities (C) of the stack (LS) of plates.
3. Rotor according to Claim 1 or 2, in which the permanent magnetic elements (M) have been magnetized in the course of their moulding and/or after their moulding, in magnetizing equipment.
4. Rotor according to any one of the preceding claims, in which said magnetic material is moulded on at least part of the terminal faces of the stack (LS) of plates.
5. Rotor according to Claim 4, in which the overmoulded magnetic material is removed locally to improve the balance of the rotor (R).
PCT/IB2008/054477 2007-11-13 2008-10-29 Permanent magnet rotor for a synchronous electrical machine, particularly for a reluctance motor WO2009063350A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO2007A000809 2007-11-13
IT000809A ITTO20070809A1 (en) 2007-11-13 2007-11-13 ROLLER WITH PERMANENT MAGNETS FOR A SYNCHRONOUS ELECTRIC MACHINE, IN PARTICULAR FOR A MOTOR WITH A REPLACEMENT.

Publications (2)

Publication Number Publication Date
WO2009063350A2 true WO2009063350A2 (en) 2009-05-22
WO2009063350A3 WO2009063350A3 (en) 2009-10-15

Family

ID=40315009

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2008/054477 WO2009063350A2 (en) 2007-11-13 2008-10-29 Permanent magnet rotor for a synchronous electrical machine, particularly for a reluctance motor

Country Status (2)

Country Link
IT (1) ITTO20070809A1 (en)
WO (1) WO2009063350A2 (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2378646A1 (en) * 2010-04-15 2011-10-19 Brusa Elektronik AG Method and device for magnetising permanently excited synchronous machines and rotor for such synchronous machines
WO2011154045A1 (en) * 2010-06-11 2011-12-15 Abb Research Ltd Rotor disc for a synchronous reluctance machine
WO2012065857A2 (en) 2010-11-17 2012-05-24 Ksb Aktiengesellschaft Reluctance motor
US9083218B2 (en) 2009-09-18 2015-07-14 Brusa Elektronik Ag Permanent magnet excited synchronous machine with embedded magnets
JP2015195650A (en) * 2014-03-31 2015-11-05 ダイキン工業株式会社 Rotor structure of magnet embedded rotary electric machine
CN106300735A (en) * 2016-08-31 2017-01-04 法乐第(北京)网络科技有限公司 The rotor of motor, motor and vehicle
CN106300734A (en) * 2016-08-31 2017-01-04 法乐第(北京)网络科技有限公司 The rotor of motor, motor and vehicle
WO2017012766A1 (en) 2015-07-17 2017-01-26 Siemens Aktiengesellschaft Reluctance rotor having an additional inherent magnetization
WO2018130490A1 (en) * 2017-01-11 2018-07-19 Continental Automotive Gmbh Method for fixing a permanent magnet in a magnet pocket of a rotor for an electric machine, rotor and electric machine
WO2018210577A1 (en) * 2017-05-16 2018-11-22 Robert Bosch Gmbh Rotor and synchronous reluctance motor
EP3457534A1 (en) * 2017-09-15 2019-03-20 Toyota Jidosha Kabushiki Kaisha Rotating electric machine

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5818140A (en) * 1995-07-11 1998-10-06 Vagati; Alfredo Synchronous reluctance electrical motor having a low torque-ripple design
US6163097A (en) * 1996-12-11 2000-12-19 Smith Technologies Development, Llc Motor generator including interconnected stators and stator laminations
US20030025415A1 (en) * 2001-08-03 2003-02-06 Haruyoshi Hino Orientation device and magnetization device
WO2007091692A1 (en) * 2006-02-08 2007-08-16 Toyota Jidosha Kabushiki Kaisha Rotor manufacturing method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5818140A (en) * 1995-07-11 1998-10-06 Vagati; Alfredo Synchronous reluctance electrical motor having a low torque-ripple design
US6163097A (en) * 1996-12-11 2000-12-19 Smith Technologies Development, Llc Motor generator including interconnected stators and stator laminations
US20030025415A1 (en) * 2001-08-03 2003-02-06 Haruyoshi Hino Orientation device and magnetization device
WO2007091692A1 (en) * 2006-02-08 2007-08-16 Toyota Jidosha Kabushiki Kaisha Rotor manufacturing method
EP1983636A1 (en) * 2006-02-08 2008-10-22 Toyota Jidosha Kabushiki Kaisha Rotor manufacturing method

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9083218B2 (en) 2009-09-18 2015-07-14 Brusa Elektronik Ag Permanent magnet excited synchronous machine with embedded magnets
WO2011128842A3 (en) * 2010-04-15 2012-11-29 Brusa Elektronik Ag Method and device for the magnetization of magnetic material pieces of a rotor in a permanently excited synchronous machine, and rotor for such a synchronous machine
WO2011128842A2 (en) 2010-04-15 2011-10-20 Brusa Elektronik Ag Method and device for the magnetization of magnetic material pieces of a rotor in a permanently excited synchronous machine, and rotor for such a synchronous machine
EP2378646A1 (en) * 2010-04-15 2011-10-19 Brusa Elektronik AG Method and device for magnetising permanently excited synchronous machines and rotor for such synchronous machines
WO2011154045A1 (en) * 2010-06-11 2011-12-15 Abb Research Ltd Rotor disc for a synchronous reluctance machine
WO2012065857A2 (en) 2010-11-17 2012-05-24 Ksb Aktiengesellschaft Reluctance motor
DE102010044046A1 (en) 2010-11-17 2012-05-24 Ksb Aktiengesellschaft reluctance motor
JP2015195650A (en) * 2014-03-31 2015-11-05 ダイキン工業株式会社 Rotor structure of magnet embedded rotary electric machine
US10153670B2 (en) 2015-07-17 2018-12-11 Siemens Aktiengesellschaft Reluctance rotor having an additional inherent magnetization
CN107852046B (en) * 2015-07-17 2019-10-08 西门子公司 Reluctance rotor with additional own magnetized portion
WO2017012766A1 (en) 2015-07-17 2017-01-26 Siemens Aktiengesellschaft Reluctance rotor having an additional inherent magnetization
CN107852046A (en) * 2015-07-17 2018-03-27 西门子公司 Reluctance rotor with additional own magnetized portion
RU2677871C1 (en) * 2015-07-17 2019-01-22 Сименс Акциенгезелльшафт Reactive rotor with additional self-magnetization
CN106300735A (en) * 2016-08-31 2017-01-04 法乐第(北京)网络科技有限公司 The rotor of motor, motor and vehicle
CN106300734A (en) * 2016-08-31 2017-01-04 法乐第(北京)网络科技有限公司 The rotor of motor, motor and vehicle
WO2018130490A1 (en) * 2017-01-11 2018-07-19 Continental Automotive Gmbh Method for fixing a permanent magnet in a magnet pocket of a rotor for an electric machine, rotor and electric machine
WO2018210577A1 (en) * 2017-05-16 2018-11-22 Robert Bosch Gmbh Rotor and synchronous reluctance motor
EP3457534A1 (en) * 2017-09-15 2019-03-20 Toyota Jidosha Kabushiki Kaisha Rotating electric machine
US10686341B2 (en) 2017-09-15 2020-06-16 Toyota Jidosha Kabushiki Kaisha Rotating electric machine

Also Published As

Publication number Publication date
WO2009063350A3 (en) 2009-10-15
ITTO20070809A1 (en) 2009-05-14

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