LINEAR FLUX SWITCHING PERMANENT MAGNET MOTOR

Abstract

A linear flux switching permanent magnet (FSPM) motor includes a longitudinal linear stator with stator teeth facing an air gap and a mover including at least one armature with armature teeth, whereby at least some of said, preferably all of said armature teeth embed at least one permanent magnet, respectively, which armature teeth are spaced apart by slots for receiving an armature winding. The permanent magnets embedded in the corresponding armature teeth protrude by an overhang over the back of the armature in a direction facing away from the air gap.

Claims

1. A linear flux switching permanent magnet (FSPM) motor comprising: a longitudinal linear stator with stator teeth facing an air gap; and a mover comprising at least one armature with armature teeth, whereby at least some of said armature teeth embed at least one permanent magnet, respectively, which armature teeth are spaced apart by slots for receiving an armature winding, wherein the permanent magnets embedded in the corresponding armature teeth protrude by an overhang over the back of the armature in a direction facing away from the air gap.

2. The motor according to claim 1, wherein the overhang is between 2 mm and 6 mm.

3. The motor according to claim 1, wherein the length of the permanent magnet in length direction of the tooth is larger than the length of the armature in length direction of the tooth.

4. The motor according to claim 1, wherein the armature teeth have an extended width portion towards the air gap, which begins in the longitudinal direction of the armature teeth already at the level of the armature windings.

5. The motor according to claim 4, wherein extended width portion of the armature teeth increases continuously without forming an edge in their sides facing the slots.

6. The motor according to claim 1, wherein at least two different permanent magnets are fitted between the first sides of each armature tooth, whereby a second of said two permanent magnet extends over the larger part of the length of the armature tooth whereas the first of said permanent magnets is located above the second permanent magnet towards the air gap.

7. The motor according to claim 6, wherein the first permanent magnet has a larger width than the second permanent magnet.

8. The motor according to claim 6, wherein the second permanent magnet has a lower remanence than the first permanent magnet.

9. The motor according to claim 4, wherein the tooth width increase is formed of the width increased portions of profile members of two adjacent armature profiles and/or from the width increase of the first permanent magnet relative to the second permanent magnet.

10. The motor according to claim 1, wherein the number of mover teeth is 22 to 42 per meter length of the mover in its moving direction.

11. The motor according to claim 1, wherein the armature is formed from U-shaped armature profiles, consisting of a profile base and at least two parallel profile members which extend perpendicular to the profile base and towards the air gap, whereby the permanent magnet(s) is/are embedded between first sides of the profile members and wherein the armature winding is located in between second sides of the profile members.

12. The motor according to claim 11, wherein the permanent magnet(s) protrude over the back of the adjacent armature profiles in a direction facing away from the air gap.

13. The motor according to claim 11, wherein the length of the permanent magnet in length direction of the tooth is larger than the length of the profile members in the length direction of the tooth.

14. The motor according to claim 1, wherein in the moving direction of the mover the width of the armature tooth in relation to the width of the adjacent armature slot is between 40 and 65%.

15. An elevator comprising a linear FSPM motor according to claim 1, wherein the mover is connected along a side of the elevator car and the stator is mounted on a beam extending along the elevator shaft.

16. The motor according to claim 1, wherein the overhang is between 3 and 5 mm.

17. The motor according to claim 1, wherein the number of mover teeth is 27 to 37 per meter length of the mover in its moving direction.

18. The motor according to claim 1, wherein in the moving direction of the mover the width of the armature tooth in relation to the width of the adjacent armature slot is between 50 and 60%.

19. The motor according to claim 2, wherein the length of the permanent magnet in length direction of the tooth is larger than the length of the armature in length direction of the tooth.

20. The motor according to claim 2, wherein the armature teeth have an extended width portion towards the air gap, which begins in the longitudinal direction of the armature teeth already at the level of the armature windings.

Description

[0051] Some prior art technologies as also the invention is hereinafter described by an embodiment in connection with the enclosed schematic drawings.

[0052] FIG. 1 shows a longitudinal cross-section through a mover and a part of a stator of an inventive FSPM motor, and

[0053] FIG. 2a shows an armature profile design according to the prior art, with a semi-closed slot,

[0054] FIGS. 2b and 2c show armature profile shapes according to the present invention,

[0055] FIGS. 3a and 3b the flux when the tooth width is reduced because of increasing the tooth number and decreasing the width of the armature profile member,

[0056] FIGS. 4a and 4b the flux in case of a known semi-closed slot,

[0057] FIGS. 5a and 5b the flux in a prior art armature tooth as well as in an armature tooth according to the invention,

[0058] FIG. 6 the force generated by a conventional mover with semi-closed slots according to FIG. 2(a) and by a mover with increased tooth width according to FIG. 2(b),

[0059] FIGS. 7a and 7b the leakage flux at the profile base with a conventional design (FIG. 7a) as well as with a permanent magnet overhang according to the invention (FIG. 7b),

[0060] FIG. 8 the flux in an inventive mover armature with increased tooth width as well as width a permanent magnet hybrid consisting of two different permanent magnets.

[0061] FIG. 1 shows a linear FSMP motor 10 comprising a mover 12 and a stator 14 which is only shown in a part as the stator normally extends over a length of several meters to tenth of meters or even to hundreds of meters in high-rise elevators in an elevator shaft. The mover 12 is usually connected alongside of a side of an elevator car and the co-action between a stator 14 and mover 12 is used to move the elevator car vertically along the elevator shaft. Between the stator 14 and the mover 12, an air gap a is provided whereby on the stator side, stator teeth 16 face to the air gap a, whereas on the side of the mover 12, an armature 13 with is provided consisting of several preferably U-shaped armature profiles 15 positioned successively and adjacent to each other in width direction w of the armature 13, only spaced apart by permanent magnets 20, 22 positioned in-between. l denominates the length direction of the armature 13 in the direction of the air gap (perpendicular to the air gap plane) a to define the areas of the armature with respect to their distance from the air gap a. These direction nominations hold true for all figures.

[0062] Each armature profile 15 consists of an profile base 21 having two parallel profile members 23 extending perpendicular to the profile base 21. The profile members 23 of two adjacent armature profiles 15 form an armature tooth together with the permanent magnets 20, 22 embedded in between. The armature teeth 18 protrude from the armature 13 in the direction of the air gap a. Between the profile members 23 of each armature profile 15 a slot for 30 is formed which is adapted to accommodate an armature winding 32.

[0063] The armature profiles 15 are regularly laminated stacks or stack segments, build up form correspondingly profiled sheet metals. An armature profile 15 may also consist of several of these U-profiles in succession as a one-piece part, reducing the number of separate armature profiles 15 for the armature 13.

[0064] The profile members 23 of two adjacent armature profiles embed a second permanent magnet 20 over most of the length l of the armature tooth 18. A first permanent magnet 22 is located on the top of the second permanent magnet 20 particularly in the area of the tooth tip 19. The first permanent magnet 22 has a larger base area and width than the second permanent magnet 20 and is aligned with its upper surface with the tip 19 of the armature tooth 18 facing the air gap a.

[0065] The second permanent magnets 20 protrude above the back of the armature 13 formed by the profile base 21 of the armature profiles 15 by an overhang d, which reduces flux leakage in the area of the profile base 21.

[0066] A linear FSPM motor with these geometrical properties has a high efficiency and a low flux leakage.

[0067] The FIGS. 2(b) and 2(c) show two different possible geometries of the armature irons or armature profiles 15 for the mover whereby in the embodiment of FIG. 2(b) the increasing width portion 36 of the profile member 23 extends over half of its length, whereas in the embodiment of FIG. 2(c), the width increasing portion 36 of the armature tooth 18 extends over the complete length l of the profile member 23.

[0068] FIGS. 3a and 3b show generally the effect of the reduction of the width of the profile members 23 on the flux between armature 13 and stator 14.

[0069] FIGS. 4a and 4b show generally the flux-increasing effect of the well-known semi-closed slot solution 36 of the profile members 23 on the flux between armature 13 and stator 14.

[0070] FIGS. 5a and 5b show the advantage of reduced flux-density between armature 13 and stator 14 when using width increased teeth 18 according to the present invention, wherein the width increased portion 36 of the profile members lead to a reduced flux density (black arrow) between armature teeth 18 and stator teeth 16.

[0071] With respect to FIGS. 6 and 7 it is referred to the general description above.

[0072] FIG. 8 shows the magnetic flux of an inventive linear FSPM motor, having width extended armature teeth 18 on one side and hybrid permanent magnets consisting of second permanent magnets 20, preferably of lower remanence (and corresponding higher de-magnetization stability) over the uppermost part of the length of the teeth 18 which are overlapped in the direction of the tooth tip 19 by first permanent magnets 22 having a larger width than the second permanent magnets 20. These second permanent magnets 22 have also a higher remanence than the first permanent magnets 20 to improve the efficiency of the motor.

[0073] In summary, the width increase of the armature teeth 18 is realised by the width increasing portions 36 of the profile members 23 as well as by the increased width of the first permanent magnets 22 with respect to the second permanent magnets 20. It can be seen that the flux density in the interface between armature teeth 18 and stator teeth 16 is moderate, which leads to less leakage flux and to a reduced tendency of irreversible de-magnetization of the permanent magnets 20, 22.

[0074] In the embodiment the width increase of the armature teeth is optional as well as the use of two permanent magnets per armature tooth.

[0075] Further, it is not necessary that each armature tooth comprises two permanent magnets.

[0076] The invention is not restricted to the disclosed embodiments but may be varied within the scope of the appended patent claims.

LIST OF REFERENCE NUMBERS

[0077] 10 linear FSPM motor [0078] 12 mover [0079] 13 armature [0080] 14 stator [0081] 15 armature profile [0082] 16 stator tooth [0083] 18 armature tooth [0084] 20 second permanent magnet [0085] 21 armature baseprofile base [0086] 22 first permanent magnet [0087] 23 armature memberprofile member [0088] 24 first side of the profile member facing the permanent magnet(s) [0089] 26 second side of the profile member facing the slot [0090] 28 level of the armature winding in the slot [0091] 30 slot [0092] 32 armature windingcopper [0093] 36 width extended parts of the profile members [0094] l length direction perpendicular to the mover area [0095] d overhang of the second permanent magnet on the armature ground [0096] w width direction of the armature in length or moving direction of the mover [0097] a air gap