Synchronous reluctance machine

Abstract

A synchronous reluctance machine includes a stator and a rotor spaced apart from the stator by an air gap. The rotor is rotatably mounted about an axis and has laminations arranged axially behind one another. Each lamination has an anisotropic magnetic structure formed by flux blocking sections and flux conducting sections, wherein the flux blocking sections and the flux conducting sections form poles of the rotor. The flux blocking sections form axial channels, wherein in at least some flux blocking sections permanent magnets are provided that do not completely occupy the respective flux blocking section and thus allow axial airflow in all flux blocking sections. The laminated core of the rotor is axially subdivided into at least two component laminated cores, with radial cooling gaps formed between the poles in the region of the q axis as viewed in circumferential direction and between the component laminated cores as viewed axially.

Claims

1. A synchronous reluctance machine, in particular a motor or generator, having a power greater than 300 kW, said synchronous reluctance machine comprising: a stator; a rotor disposed in spaced-apart relation to the stator by an air gap and mounted for rotation about an axis, said rotor including a laminated core having laminations arranged axially one behind one another and each having an anisotropic magnetic structure formed by flux blocking sections and flux conducting sections, with the flux blocking sections and the flux conducting sections forming poles of the rotor, said flux blocking sections configured to form axially extending channels, said laminated core being axially subdivided into a plurality of component laminated cores in the presence of radial cooling gaps between the poles in a region of a q axis as viewed in a circumferential direction and between neighboring ones of the component laminated cores as viewed axially, said cooling gaps opening into the air gap between the stator and the rotor; and permanent magnets provided in at least some of the flux blocking sections such as to not completely occupy the flux blocking sections, respectively, thereby allowing an axial airflow in all of the flux blocking sections, wherein at least one of the flux blocking sections is interrupted by bars and/or the permanent magnets establish a positive connection between the adjacent flux conducting sections arranged radially one above the other.

2. The synchronous reluctance machine of claim 1, wherein the positive connection is a dovetail connection.

3. The synchronous reluctance machine of claim 1, wherein the permanent magnets are arranged symmetrically to the q axis within the flux blocking sections, respectively.

4. The synchronous reluctance machine of claim 1, wherein the permanent magnets are arranged radially one above the other in a plurality of the flux blocking sections.

5. The synchronous reluctance machine of claim 1, wherein, within the flux blocking sections, permanent magnets form a positive connection with surrounding laminations.

6. The synchronous reluctance machine of claim 1, wherein the cooling gaps, as viewed from the air gap, have a radial extent which at most corresponds to a radial distance between the flux blocking sections and the air gap.

7. The synchronous reluctance machine of claim 1, wherein the radial cooling gaps between the component laminated cores of the rotor are formed by intermediate elements.

8. The synchronous reluctance machine of claim 1, wherein a number of the radial cooling gaps is at least n-1, wherein n is a number of the component laminated cores of the rotor.

9. The synchronous reluctance machine of claim 1, wherein the stator comprises radial cooling slots which are positioned at least in sections radially above the radial cooling gaps of the rotor.

10. The synchronous reluctance machine of claim 1, wherein the radial cooling gaps comprise elements for guiding an axially and/or radial cooling flow in the rotor.

11. The synchronous reluctance machine of claim 7, wherein the intermediate elements in the radial cooling gaps of the rotor are configured such as to support during operation of the synchronous reluctance machine a fan effect in a radial direction and/or an axial direction.

12. The synchronous reluctance machine of claim 1, wherein the laminated core of the rotor has an axial length which is greater than an axial length of the stator.

13. A wind power plant, comprising: a nacelle; a heat exchanger provided in or on the nacelle; a generator embodied as a reluctance machine which comprising a stator, a rotor disposed in spaced-apart relation to the stator by an air gap and mounted for rotation about an axis, said rotor including a laminated core having laminations arranged axially one behind one another and each having an anisotropic magnetic structure formed by flux blocking sections and flux conducting sections, with the flux blocking sections and the flux conducting sections forming poles of the rotor, said flux blocking sections configured to form axially extending channels, said laminated core being axially subdivided into a plurality of component laminated cores in the presence of radial cooling gaps between the poles in a region of a q axis as viewed in a circumferential direction and between neighboring ones of the component laminated cores as viewed axially, said cooling gaps opening into the air gap between the stator and the rotor, and permanent magnets provided in at least some of the flux blocking sections such as to not completely occupy the flux blocking sections, respectively, thereby allowing an axial airflow in all of the flux blocking sections, wherein at least one of the flux blocking sections is interrupted by bars and/or the permanent magnets establish a positive connection between the adjacent flux conducting sections arranged radially one above the other; and a frequency converter disposed in electrically conductive connection with the generator, wherein cooling air flows flow through the generator and/or frequency converter.

14. The wind power plant of claim 13, wherein the permanent magnets are arranged symmetrically to the q axis within the flux blocking sections, respectively.

15. The wind power plant of claim 13, wherein the permanent magnets are arranged radially one above the other in a plurality of the flux blocking sections.

16. The wind power plant of claim 13, wherein the cooling gaps, as viewed from the air gap, have a radial extent which at most corresponds to a radial distance between the flux blocking sections and the air gap.

17. The wind power plant of claim 13, wherein the radial cooling gaps between the component laminated cores of the rotor are formed by intermediate elements.

18. The wind power plant of claim 13, wherein a number of the radial cooling gaps is at least n-1, wherein n is a number of the component laminated cores of the rotor.

19. The wind power plant of claim 13, wherein the stator comprises radial cooling slots which are positioned at least in sections radially above the radial cooling gaps of the rotor.

20. The wind power plant of claim 17, wherein the intermediate elements in the radial cooling gaps of the rotor are configured such as to support during operation of the synchronous reluctance machine a fan effect in a radial direction and/or an axial direction.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention and further advantageous embodiments of the invention will be explained in more detail with reference to basic diagrams of exemplary embodiments, which show:

(2) FIG. 1 a part longitudinal section of a synchronous reluctance machine,

(3) FIG. 2 a part longitudinal section of a further synchronous reluctance machine,

(4) FIGS. 3 to 12 sections through laminations of the component laminated cores of the rotor fitted with permanent magnets,

(5) FIGS. 13 to 15 sections through laminations of the intermediate elements of the rotor,

(6) FIGS. 16 to 18 sections through laminations of the intermediate elements of the rotor with fan blades,

(7) FIGS. 19 to 21 sections through laminations of the bulkhead elements of the rotor,

(8) FIGS. 22 to 24 sections through laminations of the bulkhead elements of the rotor with closures,

(9) FIGS. 25 to 26 sections through laminations of the bulkhead elements of the rotor with tapered openings,

(10) FIGS. 27 to 29 sections through laminations of the bulkhead elements of the rotor with part openings,

(11) FIGS. 30 to 31 sections through laminations of the component laminated cores with reinforcement.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(12) FIG. 1 shows, in a part longitudinal section, a synchronous reluctance machine 20 comprising a stator 1 with a winding head 2 on each of its axial end faces each of which winding heads belongs to a winding system, not shown in greater detail, which is embedded in substantially axially extending grooves of the stator 1.

(13) The stator 1 is spaced apart from a rotor 3 by an air gap 19, wherein the rotor 3 is connected in a torsion-proof manner to a shaft 4 and mounted rotatably about an axis 18.

(14) The rotor 3 is embodied as a four-pole reluctance rotor, wherein, as viewed in the circumferential direction, flux blocking sections 14, 15, 16 and intermediate flux conducting sections 8 form four poles. In this exemplary embodiment, viewed in the radial direction, three flux blocking sections 14, 15, 16 are present.

(15) The inventive concept is not restricted to a four-pole synchronous reluctance machine 20 but can also be transferred to two-pole, six-pole, eight-pole machines etc.

(16) The stator 1, which is embodied as a laminated core, contains axial and/or in particular radial cooling channels 5, which, in accordance with this exemplary embodiment, are radially aligned with radial cooling channels 6 or cooling gaps of the rotor 3.

(17) The radial alignment of the cooling channels 6 of the rotor 3 with the cooling channels 5 of the stator 1 is advantageous for the electromagnetics since more flux is transmitted from the rotor 3 to the stator 1.

(18) The axial offset of the cooling channels 6 of the rotor 3 with respect to the cooling channels 5 of the stator 1 results in improved cooling of the entire reluctance machine while simultaneously reducing air noise.

(19) The radial cooling channels 6 of the rotor create component laminated cores 30, 31, 32, 33 of the rotor 3, which are each spaced apart by intermediate elements 7 at least in the region of the q axis.

(20) The radial cooling channels 5 of the stator 1 and the radial cooling channels 6 of the rotor 3 differ in their number and axial positioning in the axial course of the respective laminated core of the stator 1 and the rotor 3. Radial alignment of the cooling channels 5, 6 either does not occur at all or only occurs with a few predetermined cooling channels 5, 6.

(21) The flux blocking sections 14, 15, 16 form substantially axially extending cooling channels through which a cooling air flow can be conveyed. As will be demonstrated later, permanent magnets 22 are arranged in these flux blocking sections 14, 15, 16 but said permanent magnets still allow an axial cooling air flow since they either do not occupy these flux blocking sections 14, 15, 16 at all or only occupy them partially.

(22) Depending on the embodiment of these bulkhead elements 11, accordingly designed bulkhead elements 11 can now enable the topmost flux blocking section 14 or the middle flux blocking section 15 or the lowest flux blocking section 16 to be influenced in the course of its coolant flow and coolant throughput. Herein, either the entire axially-extending cooling air flow located in one of the flux blocking sections 14, 15, 16 is diverted in the region of the intermediate element 7 and conveyed radially via the air gap 19 optionally into a cooling channel 5 of the stator 1 corresponding thereto or only a part of the cooling air flow is diverted radially in the region of the intermediate element 7.

(23) If may be necessary for an axially-extending flux barrier also to supply two or more of its radial cooling gaps 6 with cooling air as uniformly as possible. To this end, the through-openings 25, 26 in the bulkhead openings 11 in accordance with FIG. 25, 26 are dimensioned appropriately for the flow in that a plurality of holes 26 or a reduced radial height or tapering 25 of the flux barrier 11 is provided for each flux barrier 11.

(24) Advantageously, the bulkhead elements 11 are also embodied as, preferably non-magnetic, laminations. The intermediate elements 7 are provided as electromagnetically conductive parts in order thereby also to enlarge the magnetically conductive part of the rotor 1, in particular in the region of the d axis, which additionally improves the power factor of the synchronous reluctance machine 20.

(25) Herein, it is also possible for permanent magnets 22 to be arranged in the intermediate elements 7 corresponding to the respective arrangement in the flux blocking sections 14, 15, 16 in accordance with FIGS. 3 to 12.

(26) FIG. 1 shows a single-inlet synchronous reluctance machine 20, wherein a cooling air flow only enters the machine, in particular the rotor 3, from one side. Independently of whether the cooling air now exits the stator 1 radially and/or the stator axially and/or the rotor 3 axially, a heat exchanger 17, which cools the cooling air back down to predetermined temperature values, can be located downstream in flow terms following the heating-up in the laminated cores of the stator 1 and rotor 3. Advantageously, herein, a frequency converter, not shown in more detail, the thermal behavior of which can also be influenced by an additional or the same heat exchanger 17 is also cooled down.

(27) Schematically depicted diversion elements 21 convey the cooling air, optionally driven by a fan 40, through the heat exchanger 17. The heat exchanger 17 is not mandatorily arranged radially above the stator 1. The heat exchanger 17 can, for example, also be located axially on the end faces of the synchronous reluctance machine 20.

(28) FIG. 2 shows a synchronous reluctance machine 20 embodied with two inlets, i.e. a cooling air flow enters the rotor 3 via the flux blocking section 14, 15, 16 from both one and the other axial end face of the rotor 3. As explained above for the single-inlet machine in accordance with FIG. 1, due to the structural design, the diversion of the cooling air in the flux blocking sections 14, 15, 16 takes place in the same or a similar manner.

(29) To separate the two cooling air flows to be moved toward each other, a partition in the form of a continuouspreferably non-magneticpartition wall 12 can be provided approximately in the center of the rotor 3 and/or the rotor 3 and the stator 1. With respect to its cross section, this is embodied like the bulkhead elements 11 in accordance with FIG. 21 or FIG. 24. As a result, the air flows are decoupled from one another, preferably in terms of flow, on both sides of the partition wall 12 and a more uniform distribution of the cooling air over the entire axial length of the machine is achieved. The non-magnetic embodiment of the partition wall 12 avoids scatter losses.

(30) FIGS. 3 to 12 each depict a conventional rotor lamination that depicts permanent magnets 22 in a wide variety of arrangements.

(31) The flux blocking sections 14, 15, 16 each extend in the shape of an arc or the shape of a bowl to the respective q axis.

(32) Like the conventional rotor laminations in accordance with FIGS. 3 to 12, the intermediate elements 7 contain cutouts, which are referred to as flux blocking sections and which also convey the air in the axial direction through the rotor 3. Laminations in accordance with FIG. 13 to FIG. 15, which enable the air in the flux blocking sections to exit respective flux blocking section and the rotor 3 radially, are provided at predetermined axial intervals. The cutouts 9 shown there extend at least from a flux blocking section, which functions as an axial cooling channel, as far as the outer diameter of the laminated rotor core of the rotor 3, i.e. as far as the air gap 19. In this embodiment, each cutout 9 between two d axes forms a cooling channel 6thus, with a four-pole reluctance rotor, four cooling gaps 6 are present after each component laminated core.

(33) Accordingly, in the case of a six-pole or eight-pole reluctance rotor, there are six or eight cooling gaps after each component laminated core.

(34) The cutout 10 in the conventional rotor lamination in accordance with FIG. 3 to FIG. 12 on the outer side of the rotor 3 also serves as an externally-situated flux barrier on the rotor 3. This optional embodiment results in a further improvement of the power factor.

(35) The externally-situated flux barrier 10 in the conventional rotor lamination in accordance with FIG. 3 to FIG. 12 can comprise air, but also non-magnetic material, in order to obtain a homogeneous air gap 19. This reduces the noise level, in particular in the case of high-revving machines.

(36) The magnetically conductive intermediate elements 7 now additionally enable magnetic flux to be conveyed in the rotor 3. The inductance in the d axis of the rotor 3 is increased thereby. The comparatively better conductance now also enables the geometric dimensions of the flux barriers, in particular the radial height thereof, to be selected as comparatively larger, whereby the inductance in the q axis falls. As a result, overall, there is greater difference in the inductances of the d and q axis and the power factor of the synchronous reluctance machine 20 is improved.

(37) An additional improvement of the power factor is achieved by the arrangement of at least one permanent magnet 22 in at least one flux barrier of at least one component laminated core and/or intermediate element 7.

(38) The magnetically conductive intermediate elements 7, in particular of the rotor 3, can be manufactured with the same tools, for example the same punching tools, as the further laminations of the rotor 3. Additional machining of the laminations, for example additional punching processes or cutting processes can also be used to manufacture suitable larger cutouts 9 or spacers. The magnetically conductive intermediate elements 7 between two component laminated cores can be embodied not only as laminated, but also as solid one-piece parts, in particular as sintered parts.

(39) In order to reduce the eddy current losses in the magnetic intermediate elements 7, these are also embodied as laminated. The number and/or axial thickness of the intermediate elements 7 arranged axially directly one behind the other produces the axial width of the cooling gap 6.

(40) In order to additionally increase the difference between the inductances L.sub.q and L.sub.d in the q and d axis of the rotor 3, the axial length of the laminated core of the rotor 3 is selected as greater than the axial length of the laminated core of the stator 1. Herein, a 10% lengthening of the laminated rotor core compared to the laminated stator core has been found to be particularly suitable.

(41) In order now to divert a cooling air flow explicitly into the radial cooling channels 6 of the rotor 3, independently of the embodiment in accordance with the synchronous reluctance machine 20 in accordance with FIG. 1, FIG. 2, or further conceivable embodiments, non-magnetically conductive bulkhead elements 11, for example in accordance with FIG. 19 to FIG. 21, are also located between the conventional laminations of the laminated rotor core in accordance with FIG. 3 to FIG. 12 and the magnetically conductive intermediate elements 7 in accordance with FIG. 13 to FIG. 15. These bulkhead elements 11 effect a radial diversion of at least one part air flow of a flux blocking section 14, 15, 16 into its respective radial cooling channel 6.

(42) As an alternative to the bulkhead openings 11 in accordance with FIG. 19 to FIG. 21, laminations with cutouts in accordance with FIG. 3 to FIG. 12i.e. magnetically conductive laminations, but without permanent magnets 22can also be provided with a closure 13 in accordance with FIG. 22 to FIG. 24 in order to act as a bulkhead element 11. This closure 13 preferably consists of non-magnetically conductive material, such as, for example, plastic.

(43) Cooling of the stator 1 with its winding system and the rotor 3 now takes place via radial cooling channels and/or axially-extending cooling channels and/or via the air gap 19. Additionally, the insertion of special intermediate elements 7 in accordance with FIG. 16 to FIG. 18 can also create an additional fan effect of the rotor 3. This takes place in particular due to the fact that the intermediate elements 7 are embodied in accordance with FIG. 16 to FIG. 18 with fan-like blades 14. These blades 14 can advantageously also simultaneously function as axial spacers between the component laminated cores 30, 31, 32, 33 of the rotor 3.

(44) Accordingly, intermediate elements 7 in accordance with FIG. 13 to FIG. 15 and/or in accordance with FIG. 16 to FIG. 18 are also possible for each reluctance rotor.

(45) In the case of a single-inlet machine in accordance with FIG. 1, the laminated core of the rotor 3 is now constructed axially as follows. A first component laminated core 30 is constructed with conventional laminations which are provided with permanent magnets 22 in accordance with one of the embodiments in accordance with FIG. 3 to FIG. 12. This is followed by an intermediate element 7 in accordance with FIG. 13, which has a predetermined axial thickness. However, it can also be embodied as laminated in one piece. This enables the cooling air flow from this flux blocking section 14 to be directed radially outward. This is then adjoined in its further axial course by a bulkhead element 11 in accordance with FIG. 19, FIG. 22, FIG. 25 or FIG. 27, which closes off the flux blocking section 14 axially completely or only partially. The flux blocking sections 15 and 16 remain partially axially open in this bulkhead element 11. At this point, no air exits radially outward from these flux blocking sections 15 and 16.

(46) This is adjoined axially by a next component laminated core 31 with conventional laminations with permanent magnets 22 in accordance with FIG. 3 to FIG. 12. This is followed by an intermediate element 7 in accordance with FIG. 14, which has a predetermined axial thickness. However, it can also be embodied as laminated in one piece. This enables the cooling air flow from this flux blocking section 15 to be directed radially outward. It is also possible for a partial air flow from the flux blocking section 14 to be directed outward here. At this point, no air exits the flux blocking section 16 radially outward.

(47) In the further axial course, this is then adjoined by a bulkhead element 11 in accordance with FIG. 20, FIG. 23, FIG. 26 or FIG. 28, which closes off the flux blocking section 14, 15 axially completely or only partially. With this bulkhead element, at least the flux blocking section 16 remains axially open.

(48) This is adjoined axially by a next component laminated core 32 with conventional laminations with permanent magnets 22 in accordance with one of FIG. 3 to FIG. 12. This is followed by an intermediate element 7 in accordance with FIG. 15, which has a predetermined axial thickness. However, it can also be embodied as laminated in one piece. This enables the cooling air flow from this flux blocking section 16 to be directed radially outward. This is then adjoined in its further axial course by a bulkhead element 11 in accordance with FIG. 21, FIG. 24, or FIG. 29, which inter alia closes off the flux blocking section 16 axially completely or only partially.

(49) Alsowhere presenta partial air flow of the flux blocking sections 14, 15 can be diverted outward here. At this point, the air from this flux blocking sections 16 in each case exits its cooling channel 6 completely or is at least partially conveyed axially onward, ultimately, in this case axially out of the laminated core of the rotor 3.

(50) If the bulkhead elements 11 only partially divert the axial air flow, the residual air flow remaining in this flux blocking section can be conveyed radially and/or axially into the bulkhead openings 11 of the other flux blocking sections located downstream in flow terms.

(51) At least in the region of the d axis, the laminated core of the rotor 3 of these embodiments is axially continuous. Flux barriers 14, 15, 16 flanking the d axis are additionally present depending upon the axial position in the laminated core of the reluctance rotor.

(52) The above-described structure from the two end faces of the rotor 3 up to partition wall 12 and the cooling principle can be transferred to a two-inlet machine in accordance with FIG. 2. Herein, ideally the partition wall 12 forms the bulkhead element, which divides the two cooling air flows flowing toward one another and diverts them radially toward the air gap 19.

(53) The generated cooling air flow through flux blocking sections 14, 15, 16 can in principle be provided by shaft-mounted fans and/or external fans.

(54) The inventive embodiment of the synchronous reluctance machine 20 with a frequency converter and the higher power factor of this dynamo-electric machine associated therewith enables this to be also used as a high-speed generator in a wind power plant, the thermal behavior of which can be optimized by the arrangement of a heat exchanger 17.

(55) Laminated cores or component laminated cores 30, 31, 32, 33 should also be understood to be one-piece solid parts that are also magnetically conductive.

(56) Depending upon the requirements imposed in the industrial environment of the synchronous reluctance machine 20 or in the case of energy generation by the synchronous reluctance machine 20, the reluctance rotor is in particular fitted with the laminations, intermediate elements 7 or bulkhead openings 11 that ensure the best power factor. Thus, a mixture of the above-described embodiments of laminations, intermediate elements 7 and bulkhead openings 11 is possible with single-inlet and dual-inlet machines and also with other cooling concepts.

(57) The intermediate elements 7 that still have flux barriers in their axial course have not yet transitioned into cooling gaps 6 can also be fitted with permanent magnets 22 in accordance with arrangements such as those in FIG. 3 to FIG. 12.

(58) The permanent magnets 22 used can be, for example, NdFeB, SaCO or ferrite, NdFeB magnets permit high flux densities while ferrite magnets are comparatively inexpensive.

(59) Since high centrifugal forces act on the flux conducting sections 8, at least one or more flux blocking sections 14, 15, 16 are interrupted by bars 23 in accordance with FIG. 30. Permanent magnets 22 can also carry out this function in that they establish a positive connection between the adjacent flux conducting sections 8 arranged radially one above the other. Thus, the positive connection can, for example, be established by a dovetail connection in accordance with FIG. 31. Combinations of the embodiments in accordance with FIG. 30 and FIG. 31 are conceivable in order to be able to absorb higher centrifugal forces.

(60) Moreover, it is advantageous for the permanent magnets 22 to be used not only as rigid elements in the flux blocking sections but also as a suspension that, as a viscous mass, is only cured in the flux blocking sections 14, 15, 16, fills these optimally and thus also creates a positive connection.