SEGMENTED STATOR

Abstract

The present disclosure relates to an electromechanical system comprising a toothed rotor and a stator segment. The stator segment comprises an armature coil defining a coil interior. The stator segment further comprises first and second stator portions, each stator portion comprising connected inner and outer radially extending poles. Each of the inner poles passes through the coil interior and each of the outer poles is provided outside of the coil interior. The stator segment further comprises a bridge spacing the stator portions and the bridge comprises a magnetic field generator arranged to generate a magnetic field between the stator portions.

Claims

1. A stator segment for an electromechanical system comprising a toothed rotor and a segmented stator, the segmented stator comprising multiple separable stator segments, at least one of the stator segments comprising: an armature coil defining a coil interior; circumferentially adjacent first and second stator portions, each stator portion of the circumferentially adjacent first and second stator portions comprising circumferentially adjacent connected inner and outer radially extending poles, each of the inner poles passing through the coil interior and each of the outer poles provided outside of the coil interior; a bridge connecting the first stator portion and the second stator portion, the bridge comprising: a magnetic field generator arranged to generate a magnetic field between the first stator portion and the second stator portion, wherein the magnetic field generator is spaced radially from the coil interior; and a circumferentially extending central portion and outer portions that extend radially inwardly at opposite ends of the central portion so as to connect the central portion to the first stator portion and the second stator portion, wherein a T-shaped recess is defined between the first stator portion, the second stator portion, and the bridge.

2. The stator segment according to claim 1, wherein the magnetic field generator comprises a field coil wound around at least a portion of the bridge.

3. The stator segment according to claim 2, wherein a portion of the field coil substantially fills a recess defined between the spaced stator portions.

4. The stator segment according to claim 1, wherein the magnetic field generator comprises one or more permanent magnets.

5. The stator segment according to claim 1, wherein the poles extend in a substantially radial direction of the stator segment.

6. The stator segment according to claim 1, wherein the bridge extends in a substantially circumferential direction of the stator segment.

7. An electromechanical system comprising: a rotor comprising a plurality of circumferentially spaced teeth; and a segmented stator comprising multiple separable stator segments, at least one stator segment of the multiple separable stator segments extending partway about the circumference of the rotor and comprising: an armature coil defining a coil interior; circumferentially adjacent first and second stator portions, each stator portion of the circumferentially adjacent first and second stator portions comprising circumferentially adjacent connected inner and outer radially extending poles, each of the inner poles passing through the coil interior and each of the outer poles provided outside of the coil interior; a bridge connecting the first stator portion and the second stator portion, the bridge comprising: a magnetic field generator arranged to generate a magnetic field between the first stator portion and the second stator portion, wherein the magnetic field generator is spaced radially from the coil interior; and a circumferentially extending central portion and outer portions that extend radially inwardly at opposite ends of the central portion so as to connect the central portion to the first stator portion and the second stator portion, wherein a T-shaped recess is defined between the first stator portion, the second stator portion, and the bridge.

8. The electromechanical system according to claim 7, wherein the magnetic field generator comprises a field coil wound around at least a portion of the bridge.

9. The electromechanical system according to claim 8, wherein a portion of the field coil substantially fills a recess defined between the spaced stator portions.

10. The electromechanical system according to claim 7, wherein the magnetic field generator comprises one or more permanent magnets.

11. The electromechanical system according to claim 7, wherein the poles extend in a substantially radial direction of the stator segment.

12. The electromechanical system according to claim 7, wherein the bridge extends in a substantially circumferential direction of the stator segment.

13. An electromechanical system comprising: a rotor comprising a plurality of circumferentially spaced teeth; and a segmented stator comprising multiple separable stator segments, at least one stator segment of the multiple separable stator segments extending partway about the circumference of the rotor and comprising: an armature coil defining a coil interior; circumferentially adjacent first and second stator portions, each stator portion comprising circumferentially adjacent connected inner and outer radially extending poles, each of the inner poles passing through the coil interior and each of the outer poles provided outside of the coil interior; and a bridge connecting the first stator portion and the second stator portion, the bridge comprising: a magnetic field generator arranged to generate a magnetic field between the first stator portion and the second stator portion, wherein the magnetic field generator is spaced radially from the coil interior; and a circumferentially extending central portion and outer portions that extend radially inwardly at opposite ends of the central portion so as to connect the central portion to the first stator portion and the second stator portion, wherein a T-shaped recess is defined between the first stator portion, the second stator portion, and the bridge; wherein the poles of the stator segment are arranged such that: when the rotor is in a first position, the inner pole of the first stator portion is completely aligned with a tooth of the rotor, the inner pole of the second stator portion is completely aligned with an air gap, the outer pole of the second stator portion is completely aligned with a tooth of the rotor and the outer pole of the first stator portion is completely aligned with an air gap; and when the rotor is in a second position, the inner pole of the second stator portion is completely aligned with a tooth of the rotor, and the inner pole of the first stator portion is completely aligned with an air gap, the outer pole of the first stator portion is completely aligned with a tooth of the rotor, and the outer pole of the second stator portion is completely aligned with an air gap.

Description

DESCRIPTION OF THE DRAWINGS

[0046] Embodiments will now be described by way of example only with reference to the accompanying drawings in which:

[0047] FIGS. 1A and 1B are schematics showing a first embodiment of the electromechanical system;

[0048] FIG. 2 is a schematic of a second embodiment of the electromechanical system;

[0049] FIG. 3 is a schematic of a third embodiment of the electromechanical system; and

[0050] FIG. 4 is a schematic of a fourth embodiment of the electromechanical system.

[0051] FIG. 5 is a schematic of a fifth embodiment of the electromechanical system.

DETAILED DESCRIPTION

[0052] The electromechanical system 100 illustrated in FIGS. 1A and 1B is an electrical generator, which comprises a toothed rotor 101 and a single structurally separated stator segment 102 of a segmented stator, the stator segment extending partway about the circumference of the rotor 101.

[0053] The stator segment 102 comprises an armature coil 103 defining a coil interior 104 and first 105a and second 105b spaced (generally U-shaped, generally ferrous) stator portions. Each stator portion 105a, 105b comprises connected inner 106a, 106b and outer 107a, 107b radially extending poles for magnetic interaction with teeth 108a, 108b of the rotor 101. As is apparent from the figures, the inner pole 106a, 106b of each stator portion 105a, 105b passes through the coil interior 104, and the outer pole 107a, 107b of each stator portion 105a, 105b is provided outside of the coil interior 104. The stator segment further comprises a bridge 109 connecting (and integrally formed with) the stator portions 105a, 105b. The bridge 109 comprises a magnetic field generator, in the form of a field coil 110, arranged to generate a magnetic field between the second stator portion 105b and the first stator portion 105a. The rotor 101 does not have any excitation mounted thereon.

[0054] As will be described in further detail below, the stator segment 102 and circumferentially-spaced teeth 108a, 108b of the toothed rotor 101 interact to produce an alternating current in the armature coil 103 (i.e. by way of electromagnetic induction). Although only two teeth 108a, 108b are shown, it should be appreciated that the rotor 101 comprises a plurality of teeth evenly spaced about its circumference.

[0055] The bridge 109 extends in a substantially circumferential direction (i.e. generally parallel to a circumference of the rotor 101) between the inner poles 106a, 106b so as to connect the armature portions 105a, 105b. In particular, the bridge 109 may be connected to a central portion of each inner pole 106a, 106b (i.e. each opposing end of the bridge 109 is connected to a respective inner pole 106a, 106b at a portion of the inner pole 106a, 106b that is centrally located with respect to a longitudinal axis of the inner pole 106a, 106b).

[0056] This arrangement of the bridge 109 results in recesses being defined between the inner poles 106a, 106b and either side of the bridge 109. The field coil 110 is wound around the bridge 109 so as to be received in the recesses. The width of the field coil 110 (i.e. in the circumferential direction of the stator segment/rotor) is substantially the same as the length of the bridge 109 (again, in the circumferential direction) such that the field coil 110 extends substantially across a width of the recesses.

[0057] The orientation of the field coil 110 (wound around the bridge 109 so as to be perpendicular to the armature coil 103) is such that, when a current (e.g. a DC current) is passed through the field coil 110, a magnetic field is generated which has a direction extending from the second armature portion 105b to the first armature portion 105a. That is, the filed coil 110 generates a magnetic field that has a north pole at an end of the bridge 109 proximate the second armature portion 105b and a south pole at an end of the bridge 109 proximate the first armature portion 105a. As will be described further below, it is this magnetic field that induces a current in the armature coil 103 and, in this respect, the current (DC current) passed through the field coil 110 can be used to control the current (AC current) induced in the armature coil 103.

[0058] The armature coil 103 is wound around the inner poles 106a, 106b such that it is oriented generally perpendicularly to the field coil 110. In this respect, opposing ends of the armature coil 103 are located in recesses defined between the inner 106a, 106b and outer poles 107a, 107b of each stator portion 105a, 105b. Thus, inner surfaces of the armature coil 103 contact respective outer surfaces of the inner poles 106a, 106b, whilst outer surfaces of the armature coil 103 are spaced from the outer poles 107a, 107b (such that there is an air gap between the armature coil 103 and the outer poles 107a, 107b).

[0059] The arrangement of the armature coil 103 and field coil 110 is such that the field coil 110 passes through the coil interior 104 of the armature coil 103. As a result, the north and south poles of the magnetic field generated by the field coil 110 are located in the coil interior 104.

[0060] The poles 106a, 106b, 107a, 107b extend inwardly in a substantially radial direction of the stator segment 102. In this way, ends of the poles 106a, 106b, 107a, 107b (proximate the rotor 101) may align with the teeth 108a, 108b of the rotor 101. Each pair of inner and outer poles 106a, 106b, 107a, 107b is connected by connecting portions 111a, 111b that extend circumferentially between the poles 106a, 106b, 107a, 107b.

[0061] As is apparent, in use, the rotor 101 undergoes rotation (in this case, in a counter-clockwise direction). In practice, this will be in the form of a continuous rotation. For the purpose of explaining the operation of the system 100, FIG. 1A shows the rotor 101 in a first position, whilst FIG. 1B shows the rotor 101 in a second position (in which the rotor 101 has been rotated counter-clockwise. Rotation of the rotor 101 between the two positions results in different alignments of the teeth 108a, 108b and air gaps 112a, 112b, 112c (defined between the teeth) with the poles 106a, 106b, 107a, 107b.

[0062] In the first position, the inner pole 106a of the first stator portion 105a is aligned with a tooth 108a of the rotor 101, and the inner pole 106b of the second stator portion 105b is aligned with an air gap 112b. Similarly, in the first position, the outer pole 107b of the second stator portion 105b is aligned with another tooth 108b of the rotor 101, and the outer pole 107a of the first stator portion 105a is aligned with an air gap 112a.

[0063] In this way, in the first position, the inner pole 106a of the first stator portion 105a and outer pole 107b of the second stator portion 105b magnetically interact with the rotor 101. Conversely, the air gaps 112a, 112b prevent magnetic interaction of the inner pole 106b of the second stator portion 105b and outer pole 107a of the first stator portion 105a with the rotor. Thus, a magnetic field is formed between the rotor 101 and the field coil 110 of the stator segment 102 via the inner pole 106a of the first stator portion 105a and outer pole 107b of the second stator portion 105b. In the present figure, that magnetic field is illustrated by way of a magnetic path 113a.

[0064] In the second position (FIG. 1B) the inner pole 106b of the second stator portion 105b is aligned with a tooth 108b of the rotor 101, and the inner pole 106a of the first stator portion 105a is aligned with an air gap 112b. The outer pole 107a of the first stator portion 105a is aligned with a tooth 108a of the rotor 101, and the outer pole 107b of the second stator portion 105b is aligned with an air gap 112c.

[0065] Hence, in the second position, a magnetic field (i.e. illustrated by way of magnetic path 113b) is defined between the rotor 101 and the field coil 110 via the inner pole 106b of the second stator portion 105b and the outer pole 107a of the first stator portion 105a.

[0066] As should be apparent, the two positions of the rotor 101 result in two different magnetic paths 113a, 113b. Due to the orientation of the field coil 110, both magnetic paths 113a, 113b extend in a generally counter-clockwise direction. The paths 113a, 113b, however, pass through the coil interior 104 of the armature coil 103 in different directions. In the first position, the magnetic path 113a passes through the coil interior 104 in a generally radially inward direction. In the second position, the magnetic path 113b passes through the coil interior 104 in a generally radially outward direction. This change in the magnetic field between the two positions of the rotor results in the induction of an alternating voltage in the armature coil 103.

[0067] It is the alignment of different pairs of the poles 106a, 106b, 107a, 107b with the teeth 108a, 108b of the rotor 101 that leads to this changing magnetic field. To allow for this alignment, the poles 106a, 106b, 107a, 107b have a circumferential spacing that is approximately half of the spacing of the teeth 108a, 108b of the rotor 101.

[0068] FIG. 2 shows a second embodiment of the electromechanical system 200. This system 200 is similar to the system 100 shown in FIGS. 1A and 1B, and for that reason, corresponding reference numerals have been used.

[0069] The system 200 differs from that described above in that the bridge 209 does not extend between the inner poles 206a, 206b. Rather, the bridge 209 comprises a circumferentially extending central portion 214 and outer portions 215a, 215b that extend radially inwardly at opposing ends of the central portion 214 so as to connect the central portion 214 to the stator portions 205a, 205b. In this embodiment, a T-shaped recess is defined between the stator portions 205a, 205b and the bridge 209, and the field coil 210 extend through this T-shaped recess and is wound around the central portion 214 of the bridge 209.

[0070] Like the previously described embodiment, the armature coil 203 is wound around the inner poles 206a, 206b, such that (in the illustrated embodiment) the bridge 209 is radially spaced from the coil interior 204 of the armature coil 203. Thus, the field coil 210 does not overlap with the armature coil 203. This can, in some cases, make it easier to manufacture and to thermally manage the system 200. For example, the field coil 210 could be wound over a larger surface area (i.e. due to the length of the bridge), which may allow a greater surface area for heat transfer to the surrounding air.

[0071] The system 300 of FIG. 3 is, again, similar to those described above. In this system 300, however, the bridge 309 extends between the inner poles 306a, 306b at radially outer portions of the inner poles 306a, 306b. Further, the recess defined between the stator portions 305a, 305b has a similar shape and size to a transverse profile of the field coil 310 such that the field coil 310 substantially fills the recess. Similarly, the recesses defined between the inner 306a, 306b and outer 307a, 307b poles of each stator portion 305a, 305b have a similar shape and size to a transverse profile of the armature coil 303 such that the armature coil 303 substantially fills these recesses. The field coil 310 is partially located in the coil interior 304 defined by the armature coil 303.

[0072] The system 400 of FIG. 4 is generally the same as that depicted in FIGS. 1A and 1B, except that this system 400 further comprises a permanent magnet 416 forming part of the bridge 409 (e.g. inserted into a cavity formed in the bridge 409). Thus, in the present system 400, the magnetic field is provided by both the permanent magnet 416 and the field coil 410. In this respect, the system 400 may be considered a hybrid system. This arrangement may improve the electrical efficacy of the system.

[0073] The permanent magnet 416 is aligned such that a line formed between its north and south poles is in a direction that is generally parallel to a direction of the bridge 409. That is, the north pole of the permanent magnet 416 is located towards one end of the bridge 409 and the south pole is located towards an opposing end of the bridge 409. Other arrangements of a permanent magnet or multiple permanent magnets can be used to a similar effect.

[0074] FIG. 5 shows a schematic of an electromechanical system 100 comprising a segmented stator 500 comprising multiple stator segments 102 surrounding a rotor 101. The stator segments are disconnected from each other, and therefore can be removed separately from the segmented stator, allowing the rotor to be removed radially by just removing two of the stator segments, rather than having to extract the rotor axially from within a single-piece stator. It will be obvious that the segmented stator could be configured to made of any number of stator segments depending on the requirements of the system. The stator segments do not have to all be identical, such that the segmented stator can comprise a mixture of stator segments according to the present disclosure, and stator segments that are not according to the present disclosure. In some embodiments, the segmented stator can comprise two or more segments, where at least one segment is removable to allow radial access to the rotor without having to extract the rotor axially from the stator.

[0075] It will be understood that the disclosure is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.