Synchronous reluctance machine

Abstract

A synchronous reluctance machine includes a stator and a rotor which is spaced apart from the stator by an air gap. The rotor rotatably mounted about an axis and includes laminations which are arranged axially one behind the other. Each lamination has an anisotropic magnetic structure which is formed by flux blocking sections and flux conducting sections. The flux blocking sections and flux conducting sections form poles of the rotor, with the flux blocking sections forming axially running channels and allowing an axial air flow. The laminated core of the rotor is axially subdivided into at least two component laminated cores, with radial cooling gaps being formed between the poles in the region of the q axis as viewed in a circumferential direction and between the component laminated cores as viewed axially.

Claims

1. A synchronous reluctance machine, comprising: a stator; and a rotor spaced apart from the stator by an air gap and mounted for rotation about an axis, said rotor comprising a laminated core including laminations arranged axially behind one another, each said lamination having an anisotropic magnetic structure formed by flux blocking sections and flux conducting sections, with the flux blocking sections and flux conducting sections forming poles of the rotor, said flux blocking sections forming axial channels to enable an axial air flow, said laminated core being subdivided axially into at least two component laminated cores, with radial cooling gaps being formed in a circumferential direction between the poles in an area of an q axis and in an axial direction between the component laminated cores for enabling at least part of the axial air flow to radially exit into the air gap, with the radial cooling gap between the at least two component laminated cores being formed by an intermediate element which is magnetically conductive.

2. The synchronous reluctance machine of claim 1, constructed as a motor or generator with a power of greater than 300 kW.

3. The synchronous reluctance machine of claim 1, wherein the radial cooling gap is defined by a radial extent which, when viewed from the air gap, corresponds at most to a radial distance between a respective one of the flux blocking sections and the air gap.

4. The synchronous reluctance machine of claim 1, wherein a number of the radial cooling gaps is at least n1, wherein n is the number of component laminated cores of the rotor.

5. The synchronous reluctance machine of claim 1, wherein the stator has radial cooling slots sized to have at least one section positioned radially over the radial cooling gaps of the rotor.

6. The synchronous reluctance machine of claim 1, wherein the radial cooling gaps have elements for conveying an axial and/or radial cooling flow in the rotor.

7. The synchronous reluctance machine of claim 1, wherein the intermediate elements are embodied in the radial cooling gaps of the rotor such that, in operation of the synchronous reluctance machine, a fan effect in radial and/or axial direction is at least supported.

8. A wind power plant, comprising: a frequency converter; a generator comprising a stator, and a rotor spaced apart from the stator by an air gap and mounted for rotation about an axis, said rotor comprising a laminated core including laminations arranged axially behind one another, each said lamination having an anisotropic magnetic structure formed by flux blocking sections and flux conducting sections, with the flux blocking sections and flux conducting sections forming poles of the rotor, said flux blocking sections forming axial channels to enable an axial air flow, said laminated core being subdivided axially into at least two component laminated cores, with radial cooling gaps being formed in a circumferential direction between the poles in an area of an q axis and in an axial direction between the component laminated cores for enabling at least part of the axial air flow to radially exit into the air gap, with the radial cooling gap between the at least two component laminated cores being formed by an intermediate element which is magnetically conductive; an electrically conductive connection configured to connect the generator to the frequency converter; and a heat exchanger disposed outside of the stator wherein the radial cooling gaps are configured for conveying an axial and/or radial cooling flow through the generator and/or frequency converter for cooling, with the cooling flow being subsequently cooled down by the heat exchanger.

9. The wind power plant of claim 8, wherein the generator has a power of greater than 300 kW.

10. The wind power plant of claim 8, wherein the radial cooling gap is defined by a radial extent which, when viewed from the air gap, corresponds at most to a radial distance between a respective one of the flux blocking sections and the air gap.

11. The wind power plant of claim 8, wherein a number of the radial cooling gaps is at least n1, wherein n is the number of component laminated cores of the rotor.

12. The wind power plant of claim 8, wherein the stator has radial cooling slots sized to have at least one section positioned radially over the radial cooling gaps of the rotor.

13. The wind power plant of claim 8, wherein the radial cooling gaps have elements for conveying an axial and/or radial cooling flow in the rotor.

14. The wind power plant of claim 8, wherein the intermediate elements are embodied in the radial cooling gaps of the rotor such that, in operation of the generator, a fan effect in radial and/or axial direction is at least supported.

15. The wind power plant of claim 8, further comprising a gondola, said heat exchanger provided inside of or on the gondola.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention, as well as further advantageous embodiments of the invention, will be explained in greater detail with reference to basic diagrams of exemplary embodiments. In the figures:

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

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

(4) FIG. 3Aa shows a section through a lamination of the component laminated cores of the rotor,

(5) FIGS. 3Bb to 3Bd show sections through laminations of the intermediate elements of the rotor,

(6) FIGS. 3Ce to 3Cg show sections through laminations of the bulkhead elements of the rotor,

(7) FIGS. 3Dh to 3Dj show sections through laminations of the bulkhead elements of the rotor with closures,

(8) FIGS. 4a to 4c show sections through laminations of the intermediate elements of a rotor with fan blades,

(9) FIGS. 5a to 5b show sections through laminations of the bulkhead elements of the rotor with narrowed openings,

(10) FIGS. 6a to 6c show sections through laminations of the bulkhead elements of the rotor with part openings,

(11) FIG. 7 shows the part longitudinal section of the synchronous reluctance machine of FIG. 1 in combination with a frequency converter,

(12) FIG. 8 shows the part longitudinal section of the further synchronous reluctance machine of FIG. 2 in combination with a frequency converter, and

(13) FIG. 9 shows a schematic overview of components of a wind power plant.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(14) FIG. 1 shows, in a part longitudinal section, a synchronous reluctance machine 20 with a stator 1, has a winding head 2 which on its axial end face sides in each case, which each belong to a winding system not shown in any greater detail, which is embedded in grooves of the stator 1 that essentially run axially.

(15) 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 is mounted rotatably about an axis 18. The rotor 3 is designed as a four-pole reluctance armature, wherein, viewed in the circumferential direction, four poles are formed by flux blocking sections 14, 15, 16 and flux conducting sections 8 present between said sections. In this exemplary embodiment, viewed in the radial direction, three flux blocking sections 14, 15, 16 are present.

(16) The inventive idea is not restricted to the four-pole synchronous reluctance machine 20 but is also able to be transferred to two-pole, six-pole, eight-pole machines etc.

(17) Located in stator 1, which is embodied as a laminated core, are axial and/or especially radial cooling channels 5, which in accordance with this exemplary embodiment, are radially flush with radial cooling channels 6 or cooling gaps of the rotor 3.

(18) Component laminated cores 30, 31, 32, 34 of the rotor 3, which are each spaced apart from one another by intermediate elements 7, at least in the region of the q axis, are created by the radial cooling channels 6 of the rotor.

(19) 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 stator 1 and rotor 3. The radial flush positioning of the cooling channels 5, 6 either does not occur at all or occurs for all or merely for a few predetermined cooling channels 5, 6.

(20) The flux blocking sections 14, 15, 16 essentially form cooling channels running axially, through which a flow of cooling air can be conveyed. Bulkhead elements 11 embodied accordingly, depending on the embodiment of said bulkhead elements 11, 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 its course of the coolant flow and coolant throughput. In this case, either the entire cooling air flow running axially located in one of the flux blocking sections 14, 15, 16 is diverted and is conveyed radially via the air gap 19 if necessary into a cooling channel 6 of the stator 1 corresponding thereto, or only a part of the cooling air flow is diverted radially.

(21) A flux barrier running axially must if necessary also supply two or more of its radial cooling slots 6 with cooling air as evenly as possible. To this end the through-openings 25, 26 in the bulkhead elements 11 in accordance with FIGS. 5, 6 are dimensioned accordingly for flow purposes, in that for each flux barrier 11 e.g. of a lamination according to FIG. 3Aa, a number of holes 26 or a reduced radial height or a narrowing 25 of the flux barrier 11 is provided.

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

(23) FIG. 1 shows a single-inlet synchronous reluctance machine 20, wherein the cooling air flow only enters the machine, in particular the rotor 3, from one side. Independently of whether the cooling air now exits radially from the stator 1 and/or axially from the rotor 3, there can be a heat exchanger 17 located downstream in flow terms after the heating-up in the laminated cores of the stator 1 and rotor 3, which cools the cooling air back down to a predetermined temperature. Advantageously in this case a frequency converter 50, shown schematically in FIG. 7, is cooled back down, which can likewise be influenced by an additional or by the same heat exchanger 17 in its temperature behavior.

(24) Diversion elements 21 shown in principle convey the cooling air, optionally driven using a fan 22, through the heat exchanger 17. The heat exchanger is not necessarily arranged radially above the stator 1. The heat exchanger 17 can for example also be located axially on the end face sides of the synchronous reluctance machine 20.

(25) FIG. 2 shows a synchronous reluctance machine 20, which is embodied with two inlets, i.e. a flow of cooling air enters into the rotor 3 via the flux blocking section 14, 15, 16 from both the one and also the other axial end face side of the rotor 3. As described above for the single-inlet machine in accordance with FIG. 1, the cooling air is diverted in the flux blocking sections 14, 15, 16, as a result of the mechanical design, in a similar or in the same manner.

(26) To separate the two cooling air flows to be moved towards each other, there can be a partition provided in the form of a continuouspreferably non-magneticpartition wall 12 roughly in the middle of rotor 3 and/or rotor 3 and stator 1. This is designed, as regards its cross section, like the bulkhead elements 1 in accordance with FIG. 3Cc or 3Dj. Thus the flows of air are decoupled from one another on both sides of the partition wall 12, preferably in terms of flow, and an even distribution of the cooling air over the entire axial length of the machine is created. Scatter losses are avoided by the amagnetic design of the partition wall 12.

(27) A conventional rotor lamination is shown in FIG. 3Aa.

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

(29) The intermediate elements 7, like the conventional rotor laminations in accordance with FIG. 3Aa, contain cutouts, which are referred to as flux blocking sections and which also convey the air in the axial direction through the rotor 3. Metal lamination sheets in accordance with FIGS. 3Bb to 3bD are provided at predetermined axial intervals, which make a radial exit from the respective flux blocking section and the rotor 3 possible for the air in the flux blocking sections. The cutouts 9 shown there extend at least from a flux blocking section, which functions as axial cooling channel, up to the outer diameter of the laminated rotor core of the rotor 3, i.e. as far as the air gap 19. Each cutout 9 between two d axes in this embodiment forms a cooling channel 6so that with a four-pole reluctance armaturefour cooling gaps 6 are present after each component laminated core.

(30) With a six-pole or eight-pole reluctance armature there are accordingly six or eight cooling gaps after each component laminated core.

(31) The cutout 10 in the conventional rotor lamination in accordance with FIG. 3Aa on the outer side of the rotor 3 likewise serves as a flux barrier lying on the outside of the rotor 3.

(32) The flux barrier 10 lying on the outside in a conventional rotor lamination in accordance with FIG. 3Aa can have air, but also amagnetic material, in order to obtain a homogeneous air gap 19. This reduces the noise level, especially with high-revving machines.

(33) Additional magnetic flux can now be conveyed in the rotor 3 by means of the magnetically conductive intermediate elements 7. The inductance in the d axis of the rotor 3 is increased thereby. The comparatively better conductance now also enables the flux barriers to be selected larger in their geometrical dimensions, in particular their radial height, whereby the inductance in the q axis falls. Thus overall a greater difference in the inductances of the d and q axis is produced and the power factor of the synchronous reluctance machine 20 is improved.

(34) The magnetically conductive intermediate elements 7, in particular of the rotor 3, can be manufactured with the same tools, e.g. with the same punch tools, as the further laminations of the rotor 3. By additional processing of the sheets, e.g. additionally punching processes or cutting processes, suitable larger cutouts 9 or spacers can also be manufactured. The magnetically conductive intermediate elements 7 between two component laminated cores can be embodied not only as metal laminated sheets, but also as massive one-piece parts, in particular as sintered parts.

(35) In order to reduce the eddy current losses in the magnetic intermediate elements 7, these are likewise embodied as metal laminated sheets. The number and/or the axial thickness of the intermediate elements 7 arranged axially immediately behind one another produces the axial thickness of the cooling gap 6.

(36) In order to additionally increase the difference between the inductances L.sub.q and L.sub.d in the q axis and the d axis, the axial length of the laminated core of the rotor 3 is selected to be greater than the axial length of the laminated core of the stator 1. In this case a 10% lengthening of the laminated rotor core in relation to the laminated stator core proves to be especially suitable.

(37) In order to now guide a flow of cooling air explicitly into the radial cooling channels 6 of the rotor 3, independently of the embodiment in accordance with the synchronous reluctance machine 20 according to FIG. 1, FIG. 2, or further conceivable versions, magnetically non-conductive bulkhead elements 11 according to FIGS. 3Ce to 3Cg are also located between the conventional laminations of the laminated rotor core according to FIG. 3Aa and the magnetically conductive intermediate elements 7 in accordance with FIGS. 3Bd to 3Bd. These bulkhead elements 11 have the effect of bringing about 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.

(38) As an alternative to the bulkhead elements 11 according to FIG. 3Ce to 3Cg, sheets with cutouts according to FIG. 3Aai.e. magnetically conductive sheetsalso with a closure 13 in accordance with FIGS. 3Dh to 3Dj, can be provided to act as a bulkhead element. This closure 13 preferably consists of magnetically non-conductive material, e.g. of plastic.

(39) The stator 1 with its winding system and also the rotor 3 are now cooled via radial cooling channels and/or cooling channels running axially and/or via the air gap 19. In addition, by insertion of specific intermediate elements 7 in accordance with FIGS. 4a to 4c, an additional fan effect of the rotor 3 can also be created. This occurs in particular by the intermediate elements 7 in accordance with FIGS. 4a to 4c being designed with fan-like blades 14. These blades 14 can advantageously also function at the same time as axial spacers between the component laminated cores 30, 31, 32, 33 of the rotor 3.

(40) Accordingly intermediate elements 7 in accordance with FIG. 3Bb to 3Bd and/or according to FIGS. 4a to 4c are also possible.

(41) The laminated core of the rotor 3, in a single-inlet machine in accordance with FIG. 1, is now structured axially as follows. A first component laminated core 30 is constructed with conventional laminations in accordance with FIG. 3Aa. This is followed by an intermediate element in accordance with FIG. 3Bb, which has a predetermined axial thickness. It can be designed in one piece or as laminated sheets. It makes it possible for the cooling flow of this flux blocking section 14 to be directed radially outwards. This is followed in the further axial course by a bulkhead element 11 in accordance with FIG. 3Ce, 3Dh, 5a or 6a, which closes off the flux blocking section 14 completely or only in part. The flux blocking sections 15 and 16 remain axially open in this bulkhead element 11. No air exits radially outwards at this point from said flux blocking sections 15 and 16.

(42) This is adjoined axially by a next component laminated core 31 with conventional laminations in accordance with FIG. 3Aa. This is followed by an intermediate element in accordance with FIG. 3Bc, which has a predetermined axial thickness. It can be designed in one piece but also as laminations. It makes it possible for the flow of cooling air of this flux blocking section 15 to be directed radially outwards. A part flow of air of the flux blocking section 14 can also be directed outwards here. No air exits radially outwards from the flux blocking section 16 at this point.

(43) This is then adjoined in its further axial course by a bulkhead element 11 in accordance with FIG. 3Cf, 3Di, 5b or 6b, which closes off the flux blocking section 14, 15 axially, completely or only in part. At least the flux blocking section 16 remains open in this bulkhead element.

(44) This is adjoined axially by a next component laminated core 32 with conventional laminations in accordance with FIG. 3Aa. This is followed by an intermediate element in accordance with FIG. 3Bd, which has a predetermined axial thickness. It can be embodied in one piece or also as laminations. It makes it possible for the flow of cooling air of this flux blocking section 16 to be conveyed radially outwards. In its further axial course it is then adjoined by a bulkhead element 11 in accordance with FIG. 3Cg, 3Dj, 5c or 6c, which, inter alia, closes off the flux blocking section axially, completely or only partly.

(45) Alsowhere presenta part flow of air of the flux blocking sections 14, 15 can be diverted outwards here. At this point the air of this flux blocking section 16 exits completely from its cooling channel 6 in each case or is at least conveyed axially onwards in part, ultimately axially out of the laminated core in this case.

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

(47) The laminated core of the rotor 3 of these versions is embodied as axially continuous, at least in the area of the d axis. Flux barriers 14, 15, 16 of the d axis flanking it are additionally present, depending on their axial position in the laminated core of the reluctance armaturedepending on which component laminated core 30, 31, 32, 33 is being considered.

(48) With a two-inlet machine in accordance with FIG. 2 the structure described above is transferrable, starting from the two end face sides of the rotor 3 up to the partition wall 12 and the cooling principle. Ideally in this case the partition wall 12 forms the bulkhead element, which divides the two flows of cooling air flowing towards one another and steers them radially to the air gap 19.

(49) The created flow of cooling air through the flux blocking sections 14, 15, 16 can basically be provided by the shaft fan 22 and/or external fans.

(50) The inventive embodiment of the synchronous reluctance machine 20 with a frequency converter 50, shown schematically in FIGS. 7 and 8, and the higher power factor of this dynamo-electric machine connected therewith also enables it to be used as a high-speed generator in a wind power plant, which can be optimized in its temperature behavior by arrangement of a heat exchanger 17. FIG. 9 shows a schematic overview of components of the wind power plant, including generator 20 having an electrically conductive connection to the frequency converter 50, with the heat exchanger 17 being provided inside a gondola 51 of the wind power plant.

(51) Laminated cores or component laminated cores 30, 31, 32, 33 are also to be understood as one-piece massive parts, which likewise have a magnetic conductivity.

(52) Depending on the requirements imposed on it in the industrial environment of the synchronous reluctance machine 20 or during generation of energy by the synchronous reluctance machine 20, the reluctance armature will be equipped especially with those laminations, intermediate elements 7 or bulkhead elements 11, which guarantee the best power factor. Thus a mixture of the aforementioned versions of laminations, intermediate elements 7 and bulkhead elements 11 is possible for single-inlet and dual-inlet machines, but also for other cooling concepts.