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WO2014032725A1 - A rotor of a permanent magnet electrical machine - Google Patents

A rotor of a permanent magnet electrical machine Download PDF

Info

Publication number
WO2014032725A1
WO2014032725A1 PCT/EP2012/066958 EP2012066958W WO2014032725A1 WO 2014032725 A1 WO2014032725 A1 WO 2014032725A1 EP 2012066958 W EP2012066958 W EP 2012066958W WO 2014032725 A1 WO2014032725 A1 WO 2014032725A1
Authority
WO
WIPO (PCT)
Prior art keywords
rotor
permanent magnet
flux
electrical machine
drop compensating
Prior art date
Application number
PCT/EP2012/066958
Other languages
French (fr)
Inventor
Jussi Puranen
Original Assignee
The Switch Drive Systems Oy
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 The Switch Drive Systems Oy filed Critical The Switch Drive Systems Oy
Priority to CN201280075399.9A priority Critical patent/CN104782027B/en
Priority to EP12758432.4A priority patent/EP2896113A1/en
Priority to KR1020157008124A priority patent/KR101706607B1/en
Priority to PCT/EP2012/066958 priority patent/WO2014032725A1/en
Publication of WO2014032725A1 publication Critical patent/WO2014032725A1/en

Links

Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K1/00Details of the magnetic circuit
    • H02K1/06Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22Rotating parts of the magnetic circuit
    • H02K1/27Rotor cores with permanent magnets
    • H02K1/2706Inner rotors
    • H02K1/272Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
    • H02K1/274Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
    • H02K1/2753Inner 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
    • H02K1/278Surface mounted magnets; Inset magnets
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K2213/00Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
    • H02K2213/03Machines characterised by numerical values, ranges, mathematical expressions or similar information

Definitions

  • the invention relates generally to rotating electrical machines. More particularly, the in- vention relates to a rotor of a permanent magnet electrical machine that comprises two or more magnetic poles.
  • a surface magnet construction is the best due to the fact that it has a lower leakage flux from the magnets.
  • a rotor construction with em- bedded magnets wastes useful flux from the magnets due to the iron bridges between the magnets.
  • each rotor pole is constructed from several magnets that are tangentially in parallel.
  • the problem with sev- eral tangentially parallel surface magnets is the large areas between the permanent magnets, where there is almost zero flux. This flux drop will substantially increase the core losses in the stator.
  • the objective of the present invention is to create a rotor and an electrical machine that ef- ficiently use the flux from the surface mounted magnets in a rotor and reduce the core losses in a stator.
  • a new rotor of a permanent magnet electrical machine comprises two or more magnetic poles.
  • the rotor according to the invention comprises: - two or more magnetic poles, and the magnetic pole comprises at least two permanent magnets attached to a surface of the rotor facing an air gap, - the magnetic pole further comprises a flux-drop compensating permanent magnet between two adjacent permanent magnets, and the flux-drop compensating permanent magnet is attached to the surface of the rotor with attaching means, and the attaching means comprises ferromagnetic material.
  • an electrical machine comprising a stator and a rotor.
  • the electrical machine according to the invention comprises:
  • a rotor of a permanent magnet electrical machine comprising two or more magnetic poles, and the magnetic pole comprises at least two permanent magnets attached to a surface of the rotor facing an air gap,
  • the magnetic pole further comprises a flux-drop compensating permanent magnet between two adjacent permanent magnets, and the flux-drop compensating permanent magnet is attached to the surface of the rotor with attaching means, and the attaching means comprises ferromagnetic material.
  • the attaching means comprises steel wedges.
  • the steel wedges extend axially.
  • the axial wedge length can be smaller, equal to or longer than the adjoining permanent magnet length.
  • the steel wedges can be shaped to lock the adjoining permanent magnets against the rotor surface.
  • the shape of the axial wedge is, for instance, trapezoidal with at least one pair of parallel sides.
  • the flux-drop compensating permanent magnet has a lower remanence flux than the adjacent permanent magnet.
  • the flux-drop compensating permanent magnet has a higher remanence flux than the adjacent permanent magnet.
  • the invention allows the use of different grades of permanent magnets as flux-drop compensating permanent magnets and permanent magnets.
  • the height of the flux-drop compensating magnet is preferably 30% - 70% of the height of the adjacent permanent magnet, depending on the grade.
  • the magnetization direction of the permanent magnets in one pole is non-radial. This further improves the magnetic flux waveform and magnetic flux density distribution.
  • the magnetization direction of the flux-drop compensating permanent magnets in one pole is radial.
  • the rotor comprises 4, 6 or 8 poles.
  • the invention is advantageous for high-speed electrical machines with a small number of poles where the width of a magnet pole is large.
  • the rotor comprises the in-axial direction, consecutive flux-drop compensating permanent magnets on the rotor surface that are skewed relative to each other by a skewing angle and the skewing angle a range is from 1 to 5 degrees.
  • the invention is applicable to different types of rotors, for example, a solid rotor, a laminated rotor or a cylindrical hollow rotor.
  • a cylindrical hollow rotor comprises a cast iron steel tube, for instance.
  • FIG. 1 shows a magnetic pole of a rotor
  • FIG. 2 shows a flux-drop compensating permanent magnet with an attaching means
  • FIG. 3 shows another flux-drop compensating permanent magnet with an attaching means
  • - Figure 4 shows a magnetic flux in a magnetic pole of a rotor
  • FIG. 5 shows the magnetization directions in a magnetic pole of a rotor
  • FIG. 8 shows a flux-drop compensating permanent magnet arrangement of the ro- tor from Figure 7;
  • FIG. 9 shows the end view of a permanent magnet electrical machine.
  • Figure 1 shows a magnetic pole 4 of a rotor 1.
  • Two permanent magnets 5 are attached to a surface 6 of the rotor 1 facing the air gap 7 in a pole 4.
  • the air gap 7 is between the rotor 1 and stator 3.
  • the magnetic pole 4 further comprises a flux-drop compensating permanent magnet 8 between two adjacent permanent magnets 5.
  • the flux-drop compensating permanent magnet 8 compensates the drop of the magnetic flux from permanent magnets 5 in slots between the permanent magnets 5.
  • the flux-drop compensating permanent magnet 8 is attached to the surface 6 of the rotor with an attaching means 9, and the attaching means 9 comprises ferromagnetic material.
  • the attaching means 9 is fastened to the rotor 1 by means of fasteners 10.
  • the fastener 10 is a bolt or a screw, for instance.
  • the attaching means 9 is above the flux-drop compensating permanent magnet 8 in a radial direction r facing the air gap 7, and it presses the flux-drop compensating permanent mag- net 8 against the surface 6 of the rotor 1.
  • other means for retaining the permanent magnets 5 may be used, for example, a retaining ring or a sleeve or resin.
  • Figures 2 and 3 show a flux-drop compensating permanent magnet 8', 8" with attaching means 9', 9". It is advantageous that a flux-drop compensating permanent magnet 8', 8" and the attaching means 9', 9" fill the slot between two in-tangential direction consecutive permanent magnets 5.
  • the attaching means 9', 9" is a steel wedge, for instance.
  • Figure 2 shows a flux-drop compensating permanent magnet 8' with an attaching means 9'.
  • the height of the slot h s to be filled with a flux-drop compensating permanent magnet 8' and the attaching means 9' is substantially equal to the height of the adjacent permanent magnet h.
  • the flux-drop compensating permanent magnet 8' has a lower remanence flux than the adjacent permanent magnet 5.
  • the height of the flux-drop compensating perma- nent magnet h m i is 70% of the height of the adjacent permanent magnet h.
  • Figure 3 shows another flux-drop compensating permanent magnet 8" with an attaching means 9".
  • the height of the slot h s to be filled with a flux-drop compensating permanent magnet 8" and an attaching means 9" is substantially equal to the height of the permanent magnet h.
  • the flux-drop compensating permanent magnet 8" has a higher remanence flux than the adjacent permanent magnet 5.
  • the height of the flux-drop compensating permanent magnet h ⁇ is 30% of the height of the adjacent permanent magnet h.
  • the shape of the attaching means 9, 9', 9" creates a form lock with the adjacent permanent magnets 5 on the surface 6 of the rotor 1.
  • the shape of the attaching means 9 is trapezoidal with at least one pair of parallel sides.
  • Figure 4 shows a magnetic flux in a magnetic pole of a rotor.
  • Figure 5 shows the magnetization directions in a magnetic pole of a rotor shown in Figure 4.
  • the magnetization direction of the permanent magnets 5 in the pole 4 is non-radial.
  • the magnetization direction of the flux-drop compensating permanent magnets 8 in the pole is radial r. These magnetization directions further improve the magnetic flux waveform and magnetic flux density distribution in the rotor and the air gap.
  • Figure 6 shows a rotor 1 with surface mounted permanent magnets 5.
  • the permanent magnets 5 are arranged at regular intervals around the rotor surface 6.
  • the in-axial direction x consecutive flux-drop compensating permanent magnet 8 has the same position on the rotor surface 6 in the tangential direction t.
  • the attaching means length Li is longer than the adjoining permanent magnet length L 2 .
  • the axial flux-drop compensating permanent magnet length is substantially equal to the adjoining permanent magnet length L 2 .
  • FIG. 7 shows another rotor 1 ' with surface mounted permanent magnets 5', 5".
  • the rotor 1 ' comprises a plurality of rings 1 1 formed from tangentially t alternating permanent magnets and flux-drop compensating permanent magnets.
  • the rings 11 are adjacent in the axial direction x.
  • the in-axial direction x consecutive permanent magnets 5', 5" on the rotor surface are skewed relative to each other. The aim of the skewing is to reduce cogging torque.
  • Figure 8 shows a flux-drop compensating permanent magnet 8"', 8"" arrangement of the rotor 1 ' from Figure 7. From three in-axial direction x adjacent rings 11 shown in Figure 7, two permanent magnets 5', 5" and a flux-drop compensating permanent magnet 8"', 8"" between them are shown from each ring 11. In the first ring, a flux-drop compensating permanent magnet 8"' is attached between two adjacent permanent magnets 5'. The in- axial direction x consecutive flux-drop compensating permanent magnet in the second ring 8"" is skewed relative to the flux-drop compensating permanent magnet 8"' in the previous first ring.
  • the in-axial direction x consecutive flux-drop compensating permanent magnet in the third ring 8"' is skewed relative to the flux-drop compensating permanent magnet 8"" in the previous second ring. Every second in-axial direction x consecutive flux- drop compensating permanent magnet 8"' has the same position on the rotor surface 6 in the tangential direction t.
  • the skewing angle a range is preferably from 1 to 5 degrees.
  • the length Li of the attaching means 9"', 9"" is substantially equal to the adjoining perma- nent magnet 5' length L 2 .
  • the attaching means 9"', 9"" is a steel wedge, for instance.
  • the axial flux-drop compensating permanent magnet length L 3 is substantially equal to the adjoining permanent magnet 5' length L 2 .
  • the attaching means 9"', 9"" is fastened to the rotor 1 by means of fasteners 10.
  • the fastener 10 is a bolt or a screw, for instance.
  • Rotor 1, 1 ' in Figures 6 and 7 is a solid rotor.
  • Solid rotors are advantageous compared with laminated rotors in their higher mechanical robustness and lower manufacturing cost.
  • the solid rotor's advantages are integrity, rigidity, and durability.
  • the magnetic pole arrangement described in Figures 6 and 7 is applicable also to laminated rotors or cylindrical hollow rotors.
  • Figure 9 shows a schematic illustration of a permanent magnet electrical machine 2 comprising a rotor 1 and a stator 3. Between the rotor 1 and the stator 3 is an air gap 7.
  • the ro- tor comprises six poles 4.
  • Two permanent magnets 5 are attached to the surface 6 of the rotor 1 facing the air gap 7 in each pole 4.
  • the magnetic poles 4 further comprise flux-drop compensating permanent magnets 8 between two adjacent permanent magnets 5.
  • the flux- drop compensating permanent magnet 8 is attached to the surface 6 of the rotor with attaching means 9, and the attaching means 9 comprises ferromagnetic material.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Permanent Field Magnets Of Synchronous Machinery (AREA)

Abstract

A rotor (1) of a permanent magnet electrical machine (2) comprising two or more magnetic poles (4).The magnetic pole comprises at least two permanent magnets (5) attached to a surface (6) of the rotor (1) facing an air gap (7). The magnetic pole (4) further comprises a flux-drop compensating permanent magnet (8) between two adjacent permanent magnets (5). The flux-drop compensating permanent magnet (8) is attached to the surface (6) of the rotor (1) with an attaching means (9), and the attaching means (9) comprises ferromagnetic material.

Description

A rotor of a permanent magnet electrical machine
Field of the invention
The invention relates generally to rotating electrical machines. More particularly, the in- vention relates to a rotor of a permanent magnet electrical machine that comprises two or more magnetic poles.
Background
From the electromagnetic point of view, a surface magnet construction is the best due to the fact that it has a lower leakage flux from the magnets. A rotor construction with em- bedded magnets wastes useful flux from the magnets due to the iron bridges between the magnets.
With high-speed electrical machines, however, the number of rotor poles is quite small, which leads to a relatively large width of the magnet pole. This means that each rotor pole is constructed from several magnets that are tangentially in parallel. The problem with sev- eral tangentially parallel surface magnets is the large areas between the permanent magnets, where there is almost zero flux. This flux drop will substantially increase the core losses in the stator.
Disclosure of the invention
The objective of the present invention is to create a rotor and an electrical machine that ef- ficiently use the flux from the surface mounted magnets in a rotor and reduce the core losses in a stator.
In accordance with the first aspect of the invention, a new rotor of a permanent magnet electrical machine comprises two or more magnetic poles. The rotor according to the invention comprises: - two or more magnetic poles, and the magnetic pole comprises at least two permanent magnets attached to a surface of the rotor facing an air gap, - the magnetic pole further comprises a flux-drop compensating permanent magnet between two adjacent permanent magnets, and the flux-drop compensating permanent magnet is attached to the surface of the rotor with attaching means, and the attaching means comprises ferromagnetic material. In accordance with the second aspect of the invention, there is an electrical machine, comprising a stator and a rotor. The electrical machine according to the invention comprises:
- a stator and a rotor,
- a rotor of a permanent magnet electrical machine comprising two or more magnetic poles, and the magnetic pole comprises at least two permanent magnets attached to a surface of the rotor facing an air gap,
- the magnetic pole further comprises a flux-drop compensating permanent magnet between two adjacent permanent magnets, and the flux-drop compensating permanent magnet is attached to the surface of the rotor with attaching means, and the attaching means comprises ferromagnetic material. Some other preferred embodiments of the inventions have the characteristics specified in the dependent claims.
The flux-drop compensating magnet between permanent magnets compensates the drop of the magnetic flux between the permanent magnets. The reduced drop of the magnetic flux reduces core losses in a stator. According to an embodiment of the invention, the attaching means comprises steel wedges. The steel wedges extend axially. The axial wedge length can be smaller, equal to or longer than the adjoining permanent magnet length. The steel wedges can be shaped to lock the adjoining permanent magnets against the rotor surface. The shape of the axial wedge is, for instance, trapezoidal with at least one pair of parallel sides. According to another embodiment of the invention, the flux-drop compensating permanent magnet has a lower remanence flux than the adjacent permanent magnet.
According to yet another embodiment of the invention, the flux-drop compensating permanent magnet has a higher remanence flux than the adjacent permanent magnet. The higher the remanence flux density, the higher is the useable magnetic flux density. The invention allows the use of different grades of permanent magnets as flux-drop compensating permanent magnets and permanent magnets. The height of the flux-drop compensating magnet is preferably 30% - 70% of the height of the adjacent permanent magnet, depending on the grade.
According to a further embodiment of the invention, the magnetization direction of the permanent magnets in one pole is non-radial. This further improves the magnetic flux waveform and magnetic flux density distribution.
According to another further embodiment of the invention, the magnetization direction of the flux-drop compensating permanent magnets in one pole is radial.
According to yet another further embodiment of the invention, the rotor comprises 4, 6 or 8 poles. The invention is advantageous for high-speed electrical machines with a small number of poles where the width of a magnet pole is large.
According to an embodiment of the invention, the rotor comprises the in-axial direction, consecutive flux-drop compensating permanent magnets on the rotor surface that are skewed relative to each other by a skewing angle and the skewing angle a range is from 1 to 5 degrees.
The invention is applicable to different types of rotors, for example, a solid rotor, a laminated rotor or a cylindrical hollow rotor. A cylindrical hollow rotor comprises a cast iron steel tube, for instance.
A number of exemplifying embodiments of the invention are described in the accompanying dependent claims.
Brief description of the figures
The exemplifying embodiments of the invention and their advantages are explained in greater detail below in the descriptions of the specific exemplifying embodiments with the accompanying drawings, in which:
- Figure 1 shows a magnetic pole of a rotor; - Figure 2 shows a flux-drop compensating permanent magnet with an attaching means;
- Figures 3 shows another flux-drop compensating permanent magnet with an attaching means; - Figure 4 shows a magnetic flux in a magnetic pole of a rotor;
- Figure 5 shows the magnetization directions in a magnetic pole of a rotor;
- Figure 6 shows a rotor;
- Figure 7 shows another rotor;
- Figure 8 shows a flux-drop compensating permanent magnet arrangement of the ro- tor from Figure 7;
- Figure 9 shows the end view of a permanent magnet electrical machine.
Description of exemplifying embodiments
Figure 1 shows a magnetic pole 4 of a rotor 1. Two permanent magnets 5 are attached to a surface 6 of the rotor 1 facing the air gap 7 in a pole 4. The air gap 7 is between the rotor 1 and stator 3. The magnetic pole 4 further comprises a flux-drop compensating permanent magnet 8 between two adjacent permanent magnets 5. The flux-drop compensating permanent magnet 8 compensates the drop of the magnetic flux from permanent magnets 5 in slots between the permanent magnets 5. The flux-drop compensating permanent magnet 8 is attached to the surface 6 of the rotor with an attaching means 9, and the attaching means 9 comprises ferromagnetic material. The attaching means 9 is fastened to the rotor 1 by means of fasteners 10. The fastener 10 is a bolt or a screw, for instance.
The attaching means 9 is above the flux-drop compensating permanent magnet 8 in a radial direction r facing the air gap 7, and it presses the flux-drop compensating permanent mag- net 8 against the surface 6 of the rotor 1. In addition to the attaching means 9 and the fasteners 10, also other means for retaining the permanent magnets 5 may be used, for example, a retaining ring or a sleeve or resin. Figures 2 and 3 show a flux-drop compensating permanent magnet 8', 8" with attaching means 9', 9". It is advantageous that a flux-drop compensating permanent magnet 8', 8" and the attaching means 9', 9" fill the slot between two in-tangential direction consecutive permanent magnets 5. The attaching means 9', 9" is a steel wedge, for instance. Figure 2 shows a flux-drop compensating permanent magnet 8' with an attaching means 9'. The height of the slot hs to be filled with a flux-drop compensating permanent magnet 8' and the attaching means 9' is substantially equal to the height of the adjacent permanent magnet h. The flux-drop compensating permanent magnet 8' has a lower remanence flux than the adjacent permanent magnet 5. The height of the flux-drop compensating perma- nent magnet hmi is 70% of the height of the adjacent permanent magnet h.
Figure 3 shows another flux-drop compensating permanent magnet 8" with an attaching means 9". The height of the slot hs to be filled with a flux-drop compensating permanent magnet 8" and an attaching means 9" is substantially equal to the height of the permanent magnet h. The flux-drop compensating permanent magnet 8" has a higher remanence flux than the adjacent permanent magnet 5. The height of the flux-drop compensating permanent magnet h^ is 30% of the height of the adjacent permanent magnet h.
In the figures, the shape of the attaching means 9, 9', 9" creates a form lock with the adjacent permanent magnets 5 on the surface 6 of the rotor 1. The shape of the attaching means 9 is trapezoidal with at least one pair of parallel sides. Figure 4 shows a magnetic flux in a magnetic pole of a rotor. By placing a small flux-drop compensating permanent magnet 8 between the permanent magnets 5 with a ferromagnetic attaching means 9 on top, an almost entire compensation of the flux-drop is achieved. There is nearly a full flux in the air gap 7 between the permanent magnets 5.
Figure 5 shows the magnetization directions in a magnetic pole of a rotor shown in Figure 4. The magnetization direction of the permanent magnets 5 in the pole 4 is non-radial. The magnetization direction of the flux-drop compensating permanent magnets 8 in the pole is radial r. These magnetization directions further improve the magnetic flux waveform and magnetic flux density distribution in the rotor and the air gap. Figure 6 shows a rotor 1 with surface mounted permanent magnets 5. The permanent magnets 5 are arranged at regular intervals around the rotor surface 6. The in-axial direction x consecutive flux-drop compensating permanent magnet 8 has the same position on the rotor surface 6 in the tangential direction t. The attaching means length Li is longer than the adjoining permanent magnet length L2. The axial flux-drop compensating permanent magnet length is substantially equal to the adjoining permanent magnet length L2.
Figure 7 shows another rotor 1 ' with surface mounted permanent magnets 5', 5". The rotor 1 ' comprises a plurality of rings 1 1 formed from tangentially t alternating permanent magnets and flux-drop compensating permanent magnets. The rings 11 are adjacent in the axial direction x. The in-axial direction x consecutive permanent magnets 5', 5" on the rotor surface are skewed relative to each other. The aim of the skewing is to reduce cogging torque.
Figure 8 shows a flux-drop compensating permanent magnet 8"', 8"" arrangement of the rotor 1 ' from Figure 7. From three in-axial direction x adjacent rings 11 shown in Figure 7, two permanent magnets 5', 5" and a flux-drop compensating permanent magnet 8"', 8"" between them are shown from each ring 11. In the first ring, a flux-drop compensating permanent magnet 8"' is attached between two adjacent permanent magnets 5'. The in- axial direction x consecutive flux-drop compensating permanent magnet in the second ring 8"" is skewed relative to the flux-drop compensating permanent magnet 8"' in the previous first ring. The in-axial direction x consecutive flux-drop compensating permanent magnet in the third ring 8"' is skewed relative to the flux-drop compensating permanent magnet 8"" in the previous second ring. Every second in-axial direction x consecutive flux- drop compensating permanent magnet 8"' has the same position on the rotor surface 6 in the tangential direction t. The skewing angle a range is preferably from 1 to 5 degrees.
The length Li of the attaching means 9"', 9"" is substantially equal to the adjoining perma- nent magnet 5' length L2. The attaching means 9"', 9"" is a steel wedge, for instance. The axial flux-drop compensating permanent magnet length L3 is substantially equal to the adjoining permanent magnet 5' length L2. The attaching means 9"', 9"" is fastened to the rotor 1 by means of fasteners 10. The fastener 10 is a bolt or a screw, for instance.
Rotor 1, 1 ' in Figures 6 and 7 is a solid rotor. Solid rotors are advantageous compared with laminated rotors in their higher mechanical robustness and lower manufacturing cost. The solid rotor's advantages are integrity, rigidity, and durability. However, the magnetic pole arrangement described in Figures 6 and 7 is applicable also to laminated rotors or cylindrical hollow rotors.
Figure 9 shows a schematic illustration of a permanent magnet electrical machine 2 comprising a rotor 1 and a stator 3. Between the rotor 1 and the stator 3 is an air gap 7. The ro- tor comprises six poles 4. Two permanent magnets 5 are attached to the surface 6 of the rotor 1 facing the air gap 7 in each pole 4. The magnetic poles 4 further comprise flux-drop compensating permanent magnets 8 between two adjacent permanent magnets 5. The flux- drop compensating permanent magnet 8 is attached to the surface 6 of the rotor with attaching means 9, and the attaching means 9 comprises ferromagnetic material. The specific examples provided in the description given above should not be construed as limiting. Therefore, the invention is not limited merely to the embodiments described above.
Parts list: 1 , rotor; 2 electrical machine; 3 stator; 4 magnetic pole; 5, 5 ', 5" permanent magnet; 6 surface; 7 air gap; 8, 8', 8", 8 "', 8"" flux-drop compensating magnet; 9, 9', 9", 9"', 9"" attaching means; 10 fastener; 1 1 ring; h height; hmi height; h^ height; hs height; Li length; L2 length; r radial; t tangential; x axial direction; a skewing angle.

Claims

What is claimed is:
1. A rotor (1 , 1 ') of a permanent magnet electrical machine (2) comprising two or more magnetic poles (4), and the magnetic pole comprises at least two permanent magnets (5, 5', 5") attached to a surface (6) of the rotor (1) facing an air gap (7), characterized in that the magnetic pole (4) further comprises a flux-drop compensating permanent magnet (8, 8', 8", 8"', 8"") between two adjacent permanent magnets (5, 5', 5"), and the flux-drop compensating permanent magnet (8, 8', 8", 8"', 8"") is attached to the surface (6) of the rotor (1) with attaching means (9, 9', 9", 9'", 9""), and the attaching means (9, 9', 9", 9'", 9"") comprises ferromagnetic material.
2. A rotor of a permanent magnet electrical machine according to claim 1, wherein the attaching means (9, 9', 9", 9"', 9"") comprises steel wedges.
3. A rotor of a permanent magnet electrical machine according to claim 1 or 2, wherein the flux-drop compensating permanent magnet (8, 8', 8", 8"', 8"") has a lower remanence flux than the adjacent permanent magnet (5, 5', 5").
4. A rotor of a permanent magnet electrical machine according to claim 1 or 2, wherein the flux-drop compensating permanent magnet (8, 8', 8", 8"', 8"") has a higher remanence flux than the adjacent permanent magnet (5, 5', 5").
5. A rotor of a permanent magnet electrical machine according to any of the claims 1-4, wherein the height of the flux-drop compensating magnet (hmi , h^) is 30% - 70% of the height of the adjacent permanent magnet (h).
6. A rotor of a permanent magnet electrical machine according to any of the claims 1-5, wherein the magnetization direction of the permanent magnets (5, 5', 5") in the pole (4) is non-radial.
7. A rotor of a permanent magnet electrical machine according to any of the claims 1-6, wherein the magnetization direction of the flux-drop compensating permanent magnets (8,
8', 8", 8'", 8"") in the pole (4) is radial.
8. A rotor of a permanent magnet electrical machine according to any of the claims 1-7, wherein the rotor (1, 1 ') comprises 4, 6 or 8 poles (4).
9. A rotor of a permanent magnet electrical machine according to any of the claims 1-8, wherein the in axial direction (x) consecutive flux-drop compensating permanent magnets (8, 8', 8", 8"', 8"") on the rotor surface (6) are skewed relative to each other by a skewing angle (a) and the skewing angle (a) range is from 1 to 5 degrees.
10. A rotor of a permanent magnet electrical machine according to any of the claims 1-9, wherein the rotor (1, ) comprises a solid rotor, a laminated rotor or a cylindrical hollow rotor.
11. A permanent magnet electrical machine (2) comprising a rotor (1 , 1") and a stator (3) and an air gap (7) between, wherein the rotor (1, 1") comprises a rotor (1, 1") according to any of the claims 1-10.
PCT/EP2012/066958 2012-08-31 2012-08-31 A rotor of a permanent magnet electrical machine WO2014032725A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CN201280075399.9A CN104782027B (en) 2012-08-31 2012-08-31 The rotor of magneto
EP12758432.4A EP2896113A1 (en) 2012-08-31 2012-08-31 A rotor of a permanent magnet electrical machine
KR1020157008124A KR101706607B1 (en) 2012-08-31 2012-08-31 A rotor of a permanent magnet electrical machine
PCT/EP2012/066958 WO2014032725A1 (en) 2012-08-31 2012-08-31 A rotor of a permanent magnet electrical machine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2012/066958 WO2014032725A1 (en) 2012-08-31 2012-08-31 A rotor of a permanent magnet electrical machine

Publications (1)

Publication Number Publication Date
WO2014032725A1 true WO2014032725A1 (en) 2014-03-06

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Application Number Title Priority Date Filing Date
PCT/EP2012/066958 WO2014032725A1 (en) 2012-08-31 2012-08-31 A rotor of a permanent magnet electrical machine

Country Status (4)

Country Link
EP (1) EP2896113A1 (en)
KR (1) KR101706607B1 (en)
CN (1) CN104782027B (en)
WO (1) WO2014032725A1 (en)

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CN104782027A (en) 2015-07-15
KR101706607B1 (en) 2017-02-15

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