• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A slot-wedge (101) for an electric machine comprises sheet portions (102, 103) which are one on the other so that the sheet portions constitute a layered structure. Furthermore, the slot-wedge comprises one or more electric conductor strips (105) between the sheet portions so as to constitute a capacitive shield when the slot-wedge is between adjacent teeth of the electric machine and when the electric conductor strips of the slot-wedge are connected to a constant electric potential.
    公开号:FI20175444A1
    申请号:FI20175444
    申请日:2017-05-16
    公开日:2018-11-17
    发明作者:Juha Pyrhönen
    申请人:Lappeenrannan Teknillinen Yliopisto；
    IPC主号:
    专利说明:

    Field of the technology
    The disclosure relates generally to rotating electric machines. More particularly, 5 the disclosure relates to a slot-wedge of an electric machine.
    Background
    In many cases, an electric drive comprises a frequency converter arranged to supply alternating voltages to an electric machine. The frequency converter produces high voltage gradients, i.e. high du/dt values, on windings of the electric 10 machine as a corollary of fast switching operations of power electronic components such as e.g. Insulated Gate Bipolar Transistors “IGBT”. The high voltage gradients cause in turn capacitively coupled stray currents through electric insulators between the windings and the core structure of the electric machine and also through the airgap of the electric machine. The above-mentioned stray 15 currents may flow through the bearings of the electric machine and/or through mechanical devices such as gears which are connected to the shaft of the electric machine. The stray currents are harmful as they may damage the bearings and/or the mechanical devices connected to the shaft of the electric machine.
    A known solution to reduce bearing currents is to use bearings which are 20 electrically insulated from the frame of an electric machine. This approach is however not free from challenges. On one hand, an insulator layer between a bearing and the frame may need to be relatively thick in order to achieve sufficient impedance against high frequency stray currents. On the other hand, it may be challenging to achieve sufficient mechanical strength when the insulator layer is 25 thick. Another known solution against bearing currents is to use insulated bearings where balls or other roller elements are made of electrically non-conductive material such as e.g. ceramics. A drawback of insulated bearings of the kind mentioned above is that they are relatively expensive. A third known solution against bearing currents and also against other stray currents is to provide a 30 frequency converter with output inductors or filters which reduce the voltage
    20175444 prh 16 -05- 2017 gradients. In many cases there can be, however, a need to design case-specific inductors or filters for different lengths of a cable of an electric machine. Therefore, standardization can be difficult with this approach. A fourth known approach is to provide slot insulators of an electric machine with electrical conductors which are 5 grounded so as to form a capacitive shield for reducing capacitive currents from windings to a core structure. Capacitive shielding of the kind mentioned above has its advantages and thus there is a need for further development of structures for implementing capacitive shielding.
    Summary
    The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention.
    In this document, the word “geometric” when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric point, a straight or curved geometric line, 20 a geometric plane, a non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional.
    In accordance with the invention, there is provided a new slot-wedge for an electric machine. The slot-wedge according to the invention comprises:
    - sheet portions being one on the other and constituting a layered structure, and
    - one or more electric conductor strips between the sheet portions so as to constitute a capacitive shield when the slot-wedge is between adjacent teeth of the electric machine.
    20175444 prh 16 -05- 2017
    The above-mentioned sheet portions can be for example portions of a single sheet that is bent on longitudinal side regions of the slot-wedge along geometric lines parallel with the longitudinal direction of the slot-wedge so that the portions of the sheet are arranged to be one on the other.
    The above-mentioned sheet or sheets constituting the layered structure can be made of, for example but not necessarily, fiber reinforced resin or fiber reinforced plastic. In cases where a magnetic slot-wedge is needed, the resin or plastic can be mixed with magnetically amplifying material whose relative permeability is greater than one, i.e. μΓ > 1. The magnetically amplifying material can be for 10 example iron powder.
    In accordance with the invention, there is provided also a new electric machine. The electric machine comprises:
    - a stator,
    - a rotor rotatably supported with respect to the stator, at least one of the rotor and the stator comprising a core structure and windings whose coil sides are located in slots of the core structure,
    - slot-wedges according to the invention and arranged to close the slots of the core structure, and
    - electric conductors having galvanic connections with the stator and coupled to first ends of the electric conductor strips of the slot-wedges, the second ends of the electric conductor strips being open conductor ends.
    The electric conductor strips of the slot-wedges constitute a capacitive shield which reduce capacitively coupled currents between the coil sides and the rotor. In some cases, the capacitive shield can reduce also capacitively coupled currents 25 between the coil sides and the stator core, at least in some extent.
    A number of exemplifying and non-limiting embodiments of the invention are described in accompanied dependent claims.
    20175444 prh 16 -05- 2017
    Various non-limiting exemplifying embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying embodiments when read in connection with the 5 accompanying drawings.
    The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use 10 of a or an, i.e. a singular form, throughout this document does not exclude a plurality.
    Brief description of figures
    Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below in the sense of examples and with reference 15 to the accompanying drawings, in which:
    figure 1 shows a section view of a detail of an electric machine that comprises a slot-wedge according to an exemplifying and non-limiting embodiment of the invention, and figures 2a and 2b illustrate a slot-wedge according to another exemplifying and 20 non-limiting embodiment of the invention.
    Description of exemplifying and non-limiting embodiments
    The specific examples provided in the description given below should not be construed as limiting the scope and/or the applicability of the appended claims. Furthermore, it is to be understood that lists and groups of examples provided in 25 the description given below are not exhaustive unless otherwise explicitly stated.
    Figure 1 shows a section view of a detail of an electric machine that comprises a slot-wedge 101 according to an exemplifying and non-limiting embodiment of the invention. The section is taken along a geometric plane parallel with the xy-plane
    20175444 prh 16 -05- 2017 of a coordinate system 199. Figure 1 illustrates a part of a stator 111 of the electric machine and a part of a rotor 112 of the electric machine. The rotor 112 is rotatably supported with respect to the stator 111 so that there is an airgap between the stator and the rotor. The geometric rotation axis of the rotor 112 is 5 parallel with the z-axis of the coordinate system 199. The stator comprises a core structure 113 and windings whose coil sides are located in slots of the core structure. Figure 1 illustrates a coil side 114 which is located in the slot between adjacent teeth 115 and 116 of the core structure 113. The slot-wedge 101 is located between the adjacent teeth 115 and 116 and closes the slot opening of the 10 above-mentioned slot of the core structure 113.
    The slot-wedge 101 comprises sheet portions which are one on the other so that the sheet portions constitute a layered structure. In figure 1, two of the sheet portions are denoted with references 102 and 103. The sheet portions, and thereby the layered structure, are advantageously made of electrically insulating 15 material such as for example fiber reinforced resin or fiber reinforced plastic. The slot-wedge 101 further comprises electric conductor strips between the sheet portions. In figure 1, one of the electric conductor strips is denoted with a reference 105. The electric conductor strips of the slot-wedge 101 constitute a capacitive shield for reducing capacitively coupled currents between the coil side 20 114 and the rotor 112 when the electric conductor strips are connected to a constant electric potential. Therefore, the electric conductor strips of the slotwedge 101 reduce e.g. bearing currents of the electric machine.
    The electric machine comprises electric conductors which have galvanic connections with the stator 111 and which are coupled to first ends of the electric 25 conductor strips of the slot-wedges of the electric machine. The second ends of the electric conductor strips of the slot-wedges are open conductor ends. The electric conductors can be connected for example to the frame of the electric machine, to the core structure 113 of the stator, or to another place from which there is a galvanic connection to the core structure 113 of the stator. Figure 1 30 illustrates schematically an electric conductor 117 which is coupled to the electric conductor strips of the slot-wedge 101.
    20175444 prh 16 -05- 2017
    The exemplifying electric machine which is partially illustrated in figure 1 can be an induction machine. It is also possible that slot-wedges of the kind described above are used in an electric machine type other than an induction machine. The electric machine can be e.g. a permanent magnet machine, an electrically excited 5 synchronous machine, a reluctance machine, or a direct current machine, i.e. a “DC” machine.
    In the exemplifying slot-wedge 101 illustrated in figure 1, the sheet portions are portions of a single sheet that is bent on longitudinal side regions of the slot-wedge 101 along geometric lines parallel with a longitudinal direction of the slot-wedge so 10 that the portions of the sheet are arranged to be one on the other. As illustrated in figure 1, the layered structure of the slot-wedge 101 is a flattened roll of the abovementioned sheet. The sheet portions can be attached to each other with suitable adhesive material, or the sheet portions can be fused together.
    In the exemplifying slot-wedge 101 illustrated in figure 1, each of the electric 15 conductor strips has an elongated shape and is substantially parallel with a longitudinal direction of the slot-wedge. Each conductor strip can be e.g. a roundwire.
    In a slot-wedge according to an exemplifying and non-limiting embodiment of the invention, the sheet portions comprise magnetically amplifying material whose 20 relative permeability is greater than one, i.e. μΓ > 1. The sheet portions may further comprise magnetically non-amplifying material arranged to mechanically support the magnetically amplifying material, the relative permeability of the magnetically non-amplifying material being at most one. The magnetically amplifying material can be for example iron powder, and the magnetically non-amplifying material can 25 be for example fiber reinforced resin or fiber reinforced plastic.
    Figures 2a and 2b illustrate a slot-wedge 201 according to another exemplifying and non-limiting embodiment of the invention. Figure 2a shows a view of a section taken along a line B-B shown in figure 2b, and figure 2b shows a view of a section taken along a line A-A shown in figure 2a. The section plane related to figure 2a is 30 parallel with the xy-plane of a coordinate system 299, and the section plane related to figure 2b is parallel with the xz-plane of the coordinate system 299. The slot-wedge 201 comprises sheet portions which are one on the other so that the sheet portions constitute a layered structure. As illustrated in figure 2a, the layered structure of the slot-wedge 201 is a stack of the above-mentioned sheet portions. The sheet portions can be attached to each other with suitable adhesive material, or the sheet portions can be fused together. In figure 2a, two of the sheet portions are denoted with references 202 and 203. The slot-wedge 201 further comprises electric conductor strips between the sheet portions. In figures 2a and 2b, one of the electric conductor strips of the slot-wedge 201 is denoted with a reference 205. In this exemplifying case, each electric conductor strips has an elongated portion in the longitudinal direction of the slot-wedge 201 and a plurality of branch portions in the transversal direction of the slot-wedge 201 so that the branch portions are connected to the longitudinal elongated portion. It is worth noting that many different shapes are possible for the electric conductor strips. Each conductor strip is advantageously shaped so that the electric conductor strip is free from closed loops because a changing magnetic flux via a closed loop would induce currents in the closed loop.
    The specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.
    权利要求:
    Claims (10)
    [1] 1. A slot-wedge (101, 201) for an electric machine, the slot-wedge comprising sheet portions (102, 103, 202, 203) being one on the other and constituting a layered structure, characterized in that the slot-wedge comprises one or more
    5 electric conductor strips (105, 205) between the sheet portions so as to constitute a capacitive shield when the slot-wedge is located between adjacent teeth of the electric machine.
    [2] 2. A slot-wedge according to claim 1, wherein the sheet portions (102, 103) are portions of a sheet that is bent on longitudinal side regions of the slot-wedge along
    10 geometric lines parallel with a longitudinal direction of the slot-wedge so that the portions of the sheet are arranged to be one on the other.
    [3] 3. A slot-wedge according to claim 2, wherein the layered structure is a flattened roll of the sheet.
    [4] 4. A slot-wedge according to any of claims 1-3, wherein each of the one or more 15 electric conductor strips (105) has an elongated shape and is substantially parallel with a longitudinal direction of the slot-wedge.
    [5] 5. A slot-wedge according claim 4, wherein the one or more electric conductor strips (105) are one or more round-wires.
    [6] 6. A slot-wedge according to any of claims 1-5, wherein the sheet portions 20 comprise magnetically amplifying material whose relative permeability is greater than one.
    [7] 7. A slot-wedge according to claim 6, wherein the sheet portions further comprise magnetically non-amplifying material arranged to mechanically support the magnetically amplifying material, the relative permeability of the magnetically non-
    25 amplifying material being at most one.
    [8] 8. A slot-wedge according to any of claims 1-7, wherein each of the electric conductor strips (105, 205) of the slot-wedge is shaped so that the conductor strip is free from closed loops.
    [9] 9. A slot-wedge according to any of claims 1-8, wherein the sheet portions are made of electrically insulating material.
    [10] 10. An electric machine comprising:
    - a stator (111),
    5 - a rotor (112) rotatably supported with respect to the stator, at least one of the rotor and the stator comprising a core structure (113) and windings whose coil sides (114) are located in slots of the core structure,
    - slot-wedges (101) according to any of claims 1-9 and arranged to close the slots of the core structure, and
    10 - electric conductors (117) having galvanic connections with the stator and coupled to first ends of the electric conductor strips of the slot-wedges, second ends of the electric conductor strips being open conductor ends.
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    同族专利:
    公开号 | 公开日
    EP3625876A1|2020-03-25|
    FI20175444A|2018-11-17|
    WO2018211174A1|2018-11-22|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP4069779B2|2003-03-26|2008-04-02|松下電器産業株式会社|Rotating electric machine|
    JP2005269716A|2004-03-16|2005-09-29|Yaskawa Electric Corp|Rotary electric machine|
    DE102013218822A1|2013-09-19|2015-03-19|Robert Bosch Gmbh|Slot closure for electrical machines|
    DE102014018338A1|2014-12-10|2016-06-16|Audi Ag|Electric machine and motor vehicle|
    法律状态:
    2020-01-14| PC| Transfer of assignment of patent|Owner name: LAPPEENRANNAN-LAHDEN TEKNILLINEN YLIOPISTO LUT |
    优先权:
    申请号 | 申请日 | 专利标题
    FI20175444A|FI20175444A|2017-05-16|2017-05-16|A slot-wedge of an electric machine|FI20175444A| FI20175444A|2017-05-16|2017-05-16|A slot-wedge of an electric machine|
    EP18728204.1A| EP3625876A1|2017-05-16|2018-05-15|A slot-wedge of an electric machine|
    PCT/FI2018/050361| WO2018211174A1|2017-05-16|2018-05-15|A slot-wedge of an electric machine|
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