Abstract:
A stator for an electrical machine includes teeth assembled from a plurality of stacked laminations mounted on a cylindrical protective surface thereby forming a plurality of slots. The stator also includes an armature winding assembled within the teeth by inserting components of the armature winding into the plurality of stator slots from positions external to the teeth in a manner that facilitates mitigating potential for coil distortion. The armature winding includes a plurality of coils that each include an end winding. The stator further includes a segmented yoke inserted around the armature winding in a manner that facilitates mitigating a potential for disturbing the end winding of the coils. Independently assembling the stator components in this manner facilitates varying a thickness and/or the number of heat conducting laminations between the yoke and teeth that subsequently facilitates heat transfer from the armature winding to an outer pressure casing of the machine.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to fluid transport systems and, more particularly, to methods and apparatus for using an electrical machine to transport fluids through a pipeline. 
         [0002]    Fluid transport is used in a variety of different industries including, but not limited to, the chemical, oil and gas industries. In one known fluid transport application fluids are transported from on-shore or off-shore locations to processing plants for subsequent use. In other known applications, fluid transport is used in hydrocarbon processing industries and chemical industries, and to facilitate distribution to end-users. 
         [0003]    At least some known fluid transport stations use fluid transport apparatus such as compressors, fans and/or pumps that are driven by gas turbines. Some of these turbines drive the associated fluid transport apparatus via a gearbox that either increases or decreases a gas turbine output drive shaft speed to a predetermined apparatus drive shaft speed. Electrical machines (i.e., electrically-powered drive motors, or electric drives) may be advantageous over mechanical drives (i.e., gas turbines) in operational flexibility (variable speed for example), maintainability, lower capital cost and lower operational cost, better efficiency and environmental compatibility. Additionally, electric drives are generally simpler in construction than mechanical drives, generally require a smaller foot print, may be easier to integrate with the fluid transport apparatus, may eliminate the need for a gearbox, and/or may be more reliable than mechanical drives. 
         [0004]    However, systems using electric drives may be less efficient than those systems using mechanical drives. At least some factors affecting electric drive efficiency include electrical and electronic topologies of motor drive and drive controls, electrical power source quality and efficiency, size and weight of electric drive components (stators for example) and magnetic coupling strength. Moreover, fluid transport apparatus electric drives generate heat via the drive components, within the stators for example, and may require supplemental systems to facilitate heat removal. For example, some known electric drives use the fluid being transported as the primary heat transfer medium and channel the fluid through and around the stator. However, in some cases, the fluid being transported may have aggressive constituents or impurities which may adversely affect the efficiency of the components being used. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    In one aspect, a stator assembly for an electrical machine is provided. The stator assembly includes a pressure vessel including at least one enclosure defined therein. The stator assembly also includes a yoke within the pressure vessel that includes a plurality of members. Each of the members includes at least one mating surface and the members are removably coupled together along the mating surfaces. The stator assembly further includes a plurality of teeth within the yoke defining a plurality of slots such that adjacent teeth define a slot therebetween. 
         [0006]    In another aspect, a stator assembly for an electrical machine is provided. The stator assembly includes a pressure vessel and a yoke in thermal communication with the pressure vessel to facilitate heat removal from the stator assembly. The stator assembly also includes a plurality of teeth including a plurality of laminations. The plurality of laminations includes at least one of a first lamination having a first thermal conductivity and a first magnetic permeability and at least one of a second lamination having a second thermal conductivity and a second magnetic permeability. The first thermal conductivity is different than the second thermal conductivity and the first magnetic permeability is different than the second magnetic permeability. The second lamination includes a first portion that extends radially within the plurality of teeth with a first predetermined axial thickness and a second portion that extends radially within the yoke with a second predetermined axial thickness. The second portion is in thermal communication with the pressure vessel to facilitate heat removal from the stator assembly. 
         [0007]    In a further aspect, a fluid transport station is provided. The fluid transport station includes a fluid transport assembly. The fluid transport assembly includes at least one rotatable shaft. The station also includes a drive motor including a rotor assembly and a stator assembly that further includes a pressure vessel, a yoke, and a plurality of teeth. The pressure vessel includes at least one enclosure defined therein and the yoke includes a plurality of members. Each of the members includes at least one mating surface and the members are removably coupled together along the mating surfaces. The yoke is positioned within the pressure vessel. The plurality of teeth define a plurality of slots such that adjacent teeth define a slot therebetween. The plurality of teeth are positioned within the yoke. The rotor is magnetically coupled to the stator assembly. The drive motor rotor assembly is rotatably coupled to the fluid transport assembly at least one rotatable shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional schematic view of an exemplary fluid transport station; 
           [0009]      FIG. 2  is a cross-sectional schematic view of an exemplary electric motor that may be used with the fluid transport station shown in  FIG. 1 ; 
           [0010]      FIG. 3  is a skewed axial schematic view of a portion of an exemplary stator enclosure that may be used with the electric motor shown in  FIG. 2 ; 
           [0011]      FIG. 4  is a skewed axial schematic of an exemplary teeth portion of an exemplary stator assembly that may be used with the electric motor shown in  FIG. 2 ; 
           [0012]      FIG. 5  is an axial schematic view of a portion of an alternative enclosure teeth portion that may be used with the electric motor shown in  FIG. 2 ; 
           [0013]      FIG. 6  is an axial schematic view of a portion of an alternative enclosure teeth portion that may be used with the electric motor shown in  FIG. 2 ; 
           [0014]      FIG. 7  is an axial schematic view of a portion of an alternative enclosure teeth portion that may be used with the electric motor shown in  FIG. 2 ; 
           [0015]      FIG. 8  is an axial schematic view of a portion of an alternative enclosure teeth portion that may be used with the electric motor shown in  FIG. 2 ; 
           [0016]      FIG. 9  is a skewed axial schematic view of an exemplary yoke portion of the exemplary stator assembly that may be used with the electric motor shown in  FIG. 2 ; 
           [0017]      FIG. 10  is a cross-sectional schematic view of a plurality of thermally conductive laminations of the exemplary stator assembly that may be used with the electric motor shown in  FIG. 2 ; 
           [0018]      FIG. 11  is a cross-sectional schematic view of an alternative stator with a plurality of thermally conductive laminations in the yoke portion that are thicker than those in the teeth portion that may be used with the electric motor shown in  FIG. 2 ; 
           [0019]      FIG. 12  is a cross-sectional schematic view of an alternative stator with a plurality of thermally conductive laminations in the teeth portion that are thicker than those in the yoke portion that may be used with the electric motor shown in  FIG. 2 ; 
           [0020]      FIG. 13  is a cross-sectional schematic view of a plurality of alternative thermally conductive stator laminations with a varying axial pitch that may be used with the electric motor shown in  FIG. 2 ; 
           [0021]      FIG. 14  is a cross-sectional schematic view of a plurality of exemplary armature windings that may be used with the electric motor shown in  FIG. 2 ; 
           [0022]      FIG. 15  is a skewed axial schematic of the stator teeth portion coupled to a stator enclosure center portion that may be used with the electric motor shown in  FIG. 2 ; 
           [0023]      FIG. 16  is a cross-sectional axial schematic view of the plurality of exemplary armature windings that may be used with the electric motor shown in  FIG. 2 ; 
           [0024]      FIG. 17  is a cross-sectional axial schematic view of a plurality of yoke portion segments that are coupled over the plurality of armature windings to form an exemplary stator core portion that may be used with the electric motor shown in  FIG. 2 ; 
           [0025]      FIG. 18  is a skewed axial schematic view of an exemplary pressure vessel that may be used with the electric motor shown in  FIG. 2 ; and 
           [0026]      FIG. 19  is an axial schematic view of the exemplary pressure vessel that may be used with the electric motor shown in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]      FIG. 1  is a cross-sectional schematic view of an exemplary fluid transport station  100 . In the exemplary embodiment, station  100  is a submerged natural gas compressing station  100  that includes a fluid transport assembly  102 . In the exemplary embodiment, assembly  102  is a multi-stage compressor  102  that is rotatingly coupled to an electric drive motor  104 . Alternatively, assembly  102  may be, but is not limited to being a pump or a fan. Station  100  may be positioned in any geographical location and may facilitate transport of any fluid wherein predetermined operational parameters are attained. Examples of fluids that may be transported by station  100  include, but are not limited to untreated methane channeled to station  100  from a natural source (not shown in  FIG. 1 ). 
         [0028]    In the exemplary embodiment, motor  104  is a permanent magnet-type electric motor  104  designed for operating speeds above the maximum speed of 3600 revolutions per minute typically associated with synchronous motors powered by a 60 Hz electrical power source. Therefore, motor  104  is generally referred to as a “super-synchronous” motor. More specifically, in the exemplary embodiment, motor  104  includes a variety of features that may be advantageous over alternative drive mechanisms. For example, in the exemplary embodiment, motor  104  may attain speeds in a range of approximately 8,000 to 20,000 revolutions per minute (rpm) without using additional components, for example, gearboxes to facilitate increasing output speed. Alternately, motor  104  speeds in excess of 20,000 rpm may be used. The increased speeds facilitate a rapid pressurization of the gas, thus increasing the efficiency and effectiveness of compressing station  100 . Additionally, in this embodiment, the elimination of additional components, for example, gearboxes, results in station  100  requiring a smaller foot print and the elimination of the associated maintenance. Another feature of this embodiment is the elimination of wearable components, such as carbon-based slip rings. As a result, in the exemplary embodiment, the reliability of the compressing station  100  is facilitated to be increased with motor  104 . Alternatively, motor  104  may be a permanent magnet-type synchronous motor, a separately excited motor, an induction motor, or any other drive device that attains predetermined operational parameters and that enables station  100  to function as described herein. 
         [0029]    Compressor  102  is positioned and fixedly secured within a compressor housing  103 . Motor  104  is positioned and fixedly secured within a pressure vessel  105 . In the exemplary embodiment, housing  103  and pressure vessel  105  are fabricated as individual components and coupled together by methods known in the art. Alternatively, housing  103  and pressure vessel  105  may be fabricated as an integrated (unitary) member. Also, in the exemplary embodiment, housing  103  and pressure vessel  105  are fabricated via a casting or a forging process. Alternatively, housing  103  and pressure vessel  105  may be fabricated using any method known in the art, for example, a welding process that enables housing  103  and pressure vessel  105  to be fabricated and assembled as described herein. Housing  103  includes a compressor suction fixture  108  that is coupled in flow communication to an inlet pipeline  110 . Pipeline  110  may be fabricated of metal, rubber, polyvinylchloride (PVC), or any material that attains predetermined operational parameters associated with the fluid being transported and the location of station  100 . 
         [0030]    In the exemplary embodiment, station  100  also includes a compressor end piece  112  that is coupled to and extends outward from housing  103 . End piece  112  facilitates enclosing compressor  102  within station  100  subsequent to insertion of compressor  102  into housing  103  and includes a compressor discharge fixture  114  that is coupled in flow communication to a compressor outlet pipeline  116  that is substantially similar to inlet pipeline  110 . In addition, a motor end cover assembly  118  is fixedly coupled to pressure vessel  105 . End cover  118  facilitates enclosing motor  104  within station  100  subsequent to insertion of motor  104  into pressure vessel  105 . 
         [0031]    Motor  104  includes a rotor assembly  120  and a stator assembly  122  that are positioned such that a gap  124  is defined between stator assembly  122  and rotor assembly  120 . A plurality of power supply cables positioned within electric cable conduit  126  facilitate coupling station  100  to a power source, for example, a variable frequency drive (VFD) (not shown in  FIG. 1 ). When stator assembly  122  is powered, an electromagnetic field is induced within motor  104 . Gap  124  facilitates magnetic coupling of rotor assembly  120  and stator assembly  122  to generate a torque that induces rotation in rotor assembly  120 . 
         [0032]    Compressor  102  includes a rotatable drive shaft  128  that is rotatably coupled to rotor assembly  120 . In the exemplary embodiment, compressor  102  includes a plurality of compressor stages  130 . Alternatively, compressor  102  may include only one stage. Rotor assembly  120  and shaft  128  are rotatable about an axis of rotation  132 . System  100  further includes a motor-compressor housing seal  137  that facilitates mitigating flow communication between motor pressure vessel  105  of compressor housing  103 . Axis of rotation  132  may be in any orientation that facilitates attaining predetermined operational parameters of station  100  that includes, but is not limited to, horizontal and vertical orientations. 
         [0033]    During operation, the VFD supplies multi-phase alternating current to stator assembly  122  at pre-determined voltages and frequencies. A rotating electromagnetic field (not shown in  FIG. 1 ) is generated in stator assembly  122 . A second magnetic field is generated within rotor assembly  120  be methods that include, but are not limited to permanent magnets and external excitation. Interaction of magnetic fields in rotor assembly  120  and stator assembly  122  through gap  124  induces torque, and subsequently, rotation of rotor assembly  120 . 
         [0034]    Station  100  receives natural gas via inlet pipeline  110  at a first predetermined pressure. The gas is channeled to compressor  102  via suction fixture  108 . Gas subsequently flows into compressor  102  and is compressed to a greater density and smaller volume at a second predetermined pressure that is greater than the first predetermined pressure. The compressed gas is discharged to outlet pipeline  116  via discharge fixture  114 . 
         [0035]      FIG. 2  is a cross-sectional schematic view of exemplary motor  104  that may be used with fluid transport station  100 . As described above, motor  104  includes an end cover assembly  118 , rotor assembly  120 , stator assembly  122 , gap  124 , electric cable conduit  126 , axis  132  and seal  137 . Pressure vessel  105  houses motor  104 . 
         [0036]    Rotor  120  includes a central portion  140 . Central portion may include, but not be limited to a plurality of permanent magnets or a plurality of excitation windings (neither shown in  FIG. 2 ) that is encased within the periphery of portion  140 . Rotor  120  also includes outboard spindle portion  142  and an inboard spindle portion  143 . Also, portions  142  and  143  are coupled to portion  140  such that rotational forces induced within portion  140  induce rotation in portions  142  and  143  as well as portion  140 . 
         [0037]    Motor  104  further includes an out board bearing  146  and an inboard bearing  148  coupled to pressure vessel  105 . Bearings  146  and  148  facilitate radial positioning of rotor assembly  120  via rotor portions  142  and  143 . In the exemplary embodiment, bearings  146  and  148  are magnetic bearings  146  and  148  that are configured to be an active-type of magnetic bearing. More specifically, a control sub-system (not shown in  FIG. 2 ) is used in conjunction with magnetic bearings  146  and  148  to determine the radial position of the rotational bearing component (not shown in  FIG. 2 ) relative to the fixed component (not shown in  FIG. 2 ) at any given time and facilitate magnetic adjustments to correct any deviations at any given angular position. Magnetic bearings  146  and  148  facilitate operation of rotor assembly  120  at the aforementioned high speeds associated with exemplary motor  104 . Alternatively, non-magnetic bearings that may include, but not be limited to journal bearings, for example, that attain predetermined parameters, that include, but are not limited to mitigating vibration and friction losses may be used. At least one rundown bearing (not shown in  FIG. 2 ) may be positioned within motor  104  in a manner similar to bearings  146  and  148  to facilitate radial support to rotor assembly  120  in event of failure of either bearings  146  and/or  148 . Furthermore, at least one thrust bearing (not shown in  FIG. 2 ) may be positioned within motor  104  in a manner similar to bearings  146  and  148  to facilitate mitigating the effects of axial thrust of rotor assembly  120  and shaft  128  (shown in  FIG. 1 ). 
         [0038]    In the exemplary embodiment, stator assembly  122  is at least partially housed in a stator enclosure  150 .  FIG. 3  is a skewed axial schematic view of a portion of exemplary stator enclosure  150  that may be used with electric motor  104  (shown in  FIG. 2 ).  FIG. 3  is referenced in conjunction with  FIG. 2  for a discussion of enclosure  150 . Rotor  104  axis of rotation  132  is illustrated in  FIG. 3  for perspective. 
         [0039]    Station  100  may be employed in transporting fluids with aggressive properties and/or impurities. These fluids may be introduced into pressure vessel  105  for purposes of lubrication and/or cooling of motor  104  components. Enclosure  150  facilitates isolating stator  122  from fluids circulated within pressure vessel  105 . 
         [0040]    Enclosure  150  includes a center portion  152  that is radially positioned within gap  124 . In the exemplary embodiment, center portion  152  is substantially cylindrical. Alternative embodiments are discussed below. Center portion  152  includes a radially inner surface  154  and a radially outer surface  156 . At least a portion of stator assembly  122  may contact outer surface  156 . Inner surface  154  and an outer periphery of rotor portion  140  define annular gap  124 . Parameters associated with the materials used to fabricate portion  152  include, but are not limited to having electrically non-conductive properties, magnetically neutral properties, and having sufficient strength and corrosion resistance to mitigate portion  152  distortion and corrosion during operation and may also include properties that facilitate conductive heat transfer. Portion  152  may be fabricated from materials that include, but are not limited to alumina-based ceramic composites. 
         [0041]    Enclosure  150  also includes two flared portions, i.e., an outboard flared portion  158  and an inboard flared portion  160  that are coupled to and extend radially and axially from cylindrical portion  152 . In the exemplary embodiment, portions  158  and  160  are substantially conical. Portions  158  and  160  are positioned between magnetic bearings  146  and  148 , respectively, and at least a portion of stator assembly  122 . Portion  158  includes a radially inner surface  162  and a radially outer surface  164 . Portion  160  includes a radially inner surface  166  and a radially outer surface  168 . Parameters associated with the materials used to fabricate portion  158  and  160  include, but are not limited to having sufficient strength and corrosion resistance to mitigate portions  158  and  160  distortion and corrosion during operation and may also include properties that facilitate conductive heat transfer. Portions  158  and  160  may be fabricated from materials that include, but are not limited to Incoloy 925®, Inconel 718®, and stainless steel. 
         [0042]    In the exemplary embodiment, portions  152  and  158  are fabricated of similar materials that are joined at their interfaces using methods that may include, but are not limited to welding or brazing the portion  158  to portion  152 , or casting portion  158  and portion  152  as a unitary portion (not shown in  FIGS. 2 and 3 ). Subsequently, portion  160  that is fabricated of a material different from portion  158  and portion  152  is coupled to portion  152  on an axially opposing side from portion  158 . A substantially toroidal seal  170  is secured to the interface of portion  152  and portion  160  such that isolation of stator  122  from fluids transported within pressure vessel  105  is facilitated. Seal  170  may be fabricated of any materials that have properties that include, but are not limited to those that facilitate material and operational compatibility with portions  152  and  160  material properties as well as facilitate attaining predetermined operational parameters associated with motor  104 . 
         [0043]    Alternatively, portions  152  and  160  are fabricated of similar materials that are joined at their interfaces using methods that may include, but are not limited to welding or brazing the portion  160  to portion  152 , or casting portion  160  and portion  152  as a unitary portion (not shown in  FIGS. 2 and 3 ). Subsequently, portion  158  that is fabricated of a material different from portion  160  and portion  152  is coupled to portion  152  on an axially opposing side from portion  160 . A substantially toroidal seal (not shown in  FIGS. 2 and 3 ) that is substantially similar to seal  170  is secured to the interface of portion  158  and portion  152  such that isolation of stator  122  from fluids transported within pressure vessel  105  is facilitated. 
         [0044]    Also, alternatively, both portions  158  and  160  may be fabricated from materials different from portion  152  materials. In this alternative embodiment, a plurality of substantially toroidal seals  170  are secured to the interfaces of portions  152  and  160  and  152  and  158 . Further, alternatively, portions  152 ,  158  and  160  may be fabricated of similar materials that may be joined at their interfaces using methods as described above. 
         [0045]    In the exemplary embodiment, portion  152  is substantially cylindrical and portions  158  and  160  are substantially conical. Alternatively, portions  152 ,  158  and  160  may be a combination of any geometrical configurations that facilitate attaining predetermined operational parameters associated with motor  104  and station  100  (discussed further below). 
         [0046]      FIG. 4  is a skewed axial schematic of an exemplary teeth portion  202  of exemplary stator assembly  122  that may be used with electric motor  104  (shown in  FIG. 2 ).  FIG. 4  is referenced in conjunction with  FIG. 2  for a discussion of enclosure teeth portion  202 . Rotor  104  axis of rotation  132  is illustrated in  FIG. 4  for perspective. 
         [0047]    Stator assembly  122  includes a substantially cylindrical stator core portion  200 . Core portion  200  is positioned within at least a portion of a stator assembly compartment  172  defined by pressure vessel  105  and enclosure  150  (discussed further below). Core portion  200  includes a substantially cylindrical teeth portion  202  and a substantially cylindrical yoke portion  204 . Teeth portion  202  includes a plurality of adjacent stator teeth  206  wherein adjacent teeth  206  define a plurality of adjacent stator winding slots  208 . 
         [0048]    Each tooth  206  is fabricated by stacking individual laminations (not shown in  FIGS. 2 and 4 ) by methods known in the art to form teeth with predetermined axial and radial dimensions. Teeth  206  are fixedly coupled to enclosure teeth portion radially outer surface  156  circumferentially such that winding slots  208  are formed with predetermined axial and radial dimensions. In the exemplary embodiment, teeth  206  are positioned on surface  156  via axial slots using a tongue and groove arrangement (not shown in  FIGS. 2 and 4 ). Alternatively, teeth  206  are coupled to surface  156  using methods that may include, but are not limited to welding, brazing, and adhesives. 
         [0049]    In the exemplary embodiment, enclosure center portion  152  is cylindrical. Alternatively, enclosure center portion  152  may be formed with predetermined polygonal dimensions.  FIG. 5  is an axial schematic view of a portion of an alternative enclosure teeth portion  252  that may be used with electric motor  104  (shown in  FIG. 2 ). Alternative portion  252  is an extruded polygon that includes a plurality of extruded segments  253 . In this alternative embodiment, extruded segments  253  are sized and positioned such that segments  253  are substantially centered over slots  208  and a number of segments  253  equals a number of slots  208 . Moreover, in this alternative embodiment, segments  253  and teeth  206  are sized and positioned such that vertices of extruded polygonal portions  252  are substantially centered on teeth  206 . 
         [0050]      FIG. 6  is an axial schematic view of a portion of an alternative enclosure teeth portion  352  that may be used with electric motor  104  (shown in  FIG. 2 ). Alternative portion  352  is an extruded polygon that includes a plurality of extruded segments  353 . In this alternative embodiment, extruded segments  353  are sized and positioned such that segments  353  are substantially centered over teeth  206  and a number of segments  353  equals a number of slots  208 . Moreover, in this alternative embodiment, segments  253  and slots  208  are sized and positioned such that vertices of extruded polygonal portions  352  are substantially centered over slots  208 . 
         [0051]      FIG. 7  is an axial schematic view of a portion of an alternative enclosure teeth portion  452  that may be used with electric motor  104  (shown in  FIG. 2 ). Alternative portion  452  is an extruded polygon that includes a plurality of extruded segments  453 . In this alternative embodiment, extruded segments  453  are sized and positioned such that a portion of segments  453  are substantially centered over teeth  206  and a portion of segments  453  are substantially centered over slots  208  in an alternating fashion. Moreover, in this alternative embodiment, the number of segments  453  equals the sum of a number of teeth  206  and a number of slots  208 . 
         [0052]      FIG. 8  is an axial schematic view of a portion of an alternative enclosure teeth portion  552  that may be used with electric motor  104  (shown in  FIG. 2 ). Alternative portion  552  includes a geometrical shape that may be, but not be limited to a right circular cylinder or an extruded polygon. In this alternative embodiment, portion  552  includes a plurality of slots  553  defined within a radially outer surface  556  wherein a number of slots  553  equals the number of teeth  208 . Slots  553  include predetermined axial and radial dimensions that facilitate receiving teeth  206 , thereby facilitating circumferential alignment of teeth  206 . 
         [0053]      FIG. 9  is a skewed axial schematic of an exemplary yoke portion  204  of exemplary stator core portion  200  of exemplary stator assembly  122  that may be used with electric motor  104  (shown in  FIG. 2 ). Rotor  104  axis of rotation  132  is illustrated for perspective.  FIG. 9  is referenced in conjunction with  FIG. 2  for a discussion of yoke portion  204 . In the exemplary embodiment, yoke  204  includes two substantially similar yoke sections  214 . Each of yoke sections  214  includes a plurality of axial yoke mating surfaces  216 , a radially inner surface  218  and a radially outer surface  220 . Yoke sections  214  are fabricated using methods, materials and apparatus known in the art. Parameters associated with the materials used to fabricate yoke sections  214  include, but are not limited to having sufficient strength and corrosion resistance to mitigate yoke  204  distortion and corrosion during operation and may also include properties that facilitate conductive heat transfer. 
         [0054]    Yoke sections  214  are coupled at mating surfaces  216  by means of a pressure fit from an external enclosure such as pressure vessel  105  and secured using methods that include, but are not limited to welding and brazing. Yoke  204  extends over teeth portion  202  and is sized such that at least a portion of yoke radial inner surface  218  contacting at least a portion of a radial outer surface of teeth  206  is facilitated. Yoke  204  is also sized such that at least a portion of yoke radial outer surface  220  contacting a radially inner surface of pressure vessel  105  (neither shown in  FIG. 9 ) is facilitated. Moreover, yoke  204  is sized to facilitate positioning within stator compartment  172  (shown in  FIG. 2 ). 
         [0055]      FIG. 10  is a cross-sectional schematic of a plurality of thermally conductive laminations  232  and  234  of exemplary stator assembly  122  that may be used with electric motor  104  (shown in  FIG. 2 ). Rotor axis of rotation  132  is illustrated for perspective.  FIG. 10  is referenced in conjunction with  FIG. 2  for a discussion of the exemplary stator laminations. Specifically, teeth portion  202  includes a plurality of magnetic laminations  230  and a plurality of thermally conductive laminations  232 . More specifically, each tooth  206  (shown in  FIG. 4 ) includes a plurality of magnetic laminations  230  and a plurality of thermally conductive laminations  232 . Magnetic laminations  230  have a predetermined magnetic permeability such that magnetic flux generation and conduction is facilitated within core portion  200 . Thermally conductive laminations  232  have heat transfer properties that facilitate heat removal from core portion  200  more efficiently and effectively than laminations  230 . In the exemplary embodiment, thermally conductive laminations  232  have copper or copper alloy as the primary constituent. Alternatively, laminations  232  may include any number and any percentage of constituents that attain predetermined parameters that facilitate operation of motor  104 . 
         [0056]    In the exemplary embodiment, yoke portion  204  is substantially similar to the description above. A plurality of thermally conductive laminations  234  that are substantially similar to laminations  232  in teeth portion  202  are interspersed within yoke portion  204 . 
         [0057]    Laminations  232  and  230  are interspersed within teeth portion  202  and laminations  234  are interspersed within yoke portion  204  such that predetermined parameters for heat removal from core portion  200  and for magnetic coupling of stator  122  with rotor  120  across gap  124  are attained. In the exemplary embodiment, thermally conductive laminations  232  are interspersed within stator teeth portion  202  wherein there are substantially similar axial lengths, or axial pitch, between each of laminations  232 . Also, in the exemplary embodiment, thermally conductive laminations  234  are interspersed within yoke portion  204  at substantially similar axial lengths between each of laminations  234  and with a radial dimension such that thermal communication between laminations  232  and  234  is facilitated. Moreover, in the exemplary embodiment, laminations  232  and  234  within teeth portion  202  and yoke portion  204 , respectively, have substantially similar axial dimensions, i.e., thicknesses. Furthermore, in the exemplary embodiment, the thicknesses of laminations  232  are substantially uniform within core portion  200 , i.e., a substantially uniform thickness distribution of laminations  232  is attained within core portion  200  wherein the thicknesses of each of laminations  232  are substantially similar. Similarly, in the exemplary embodiment, the thicknesses of laminations  234  are substantially uniform within core portion  200 , i.e., a substantially uniform thickness distribution of laminations  234  is attained within core portion  200  wherein the thicknesses of each of laminations  234  are substantially similar. Alternatively, a distribution of differing predetermined thicknesses of laminations  232  and  234  may be used to facilitate attaining predetermined parameters that facilitate operation of motor  104 . This alternative distribution may include a uniform or non-uniform distribution of varying thicknesses. 
         [0058]      FIG. 11  is a cross-sectional schematic of an alternative stator with a plurality of thermally conductive laminations  332  and  334  in a yoke portion  304  that are thicker than those in a teeth portion  302  that may be used with electric motor  104  (shown in  FIG. 2 ). Rotor axis of rotation  132  is illustrated for perspective. Alternative stator core  300  includes alternative teeth portion  302  and alternative yoke portion  304 . Teeth portion  302  includes a plurality of magnetic laminations  330  and a plurality of thermally conductive laminations  332  that are identical to similar components in the exemplary embodiment. Yoke portion  304  includes a plurality of thermally conductive laminations  334  that are substantially similar to laminations  234  (shown in  FIG. 10 ) with the exception that an axial dimension (i.e., thickness) of laminations  334  is larger than an axial dimension (thickness) of laminations  234 . In addition, the axial dimension (thickness) of yoke portion laminations  334  is larger than an axial dimension (thickness) of teeth portion laminations  332 . This alternative embodiment facilitates a uniform temperature distribution within and heat removal from yoke portion  304 . Moreover, in this alternative embodiment, laminations  332  and  334  within teeth portion  302  and yoke portion  304 , respectively, have substantially similar axial dimensions, i.e., thicknesses. Furthermore, in this alternative embodiment, the thicknesses of laminations  332  are substantially uniform within core portion  300 , i.e., a substantially uniform thickness distribution of laminations  332  is attained within core portion  300  wherein the thicknesses of each of laminations  332  are substantially similar. Similarly, in the exemplary embodiment, the thicknesses of laminations  334  are substantially uniform within core portion  300 , i.e., a substantially uniform thickness distribution of laminations  334  is attained within core portion  300  wherein the thicknesses of each of laminations  334  are substantially similar. Alternatively, a distribution of differing predetermined thicknesses of laminations  332  and  334  may be used to facilitate attaining predetermined parameters that facilitate operation of motor  104 . This alternative distribution may include a uniform or non-uniform distribution of varying thicknesses. 
         [0059]      FIG. 12  is a cross-sectional schematic of an alternative stator with a plurality of thermally conductive laminations  432  and  434  in a tooth portion  402  that are thicker than those in a yoke portion  404  that may be used with electric motor  104  (shown in  FIG. 2 ). Rotor axis of rotation  132  is illustrated for perspective. Alternative stator core  400  includes alternative teeth portion  402  and alternative yoke portion  404 . Teeth portion  402  includes a plurality of magnetic laminations  430  that are substantially similar to laminations  230  (shown in  FIG. 10 ) in the exemplary embodiment with the exception that laminations  430  are configured to receive a plurality of alternative thermally conductive laminations  432 . Laminations  432  are substantially similar to laminations  232  (shown in  FIG. 10 ) with the exception that an axial dimension (thickness) of laminations  432  is larger than an axial dimension (thickness) of laminations  232 . Yoke portion  404  includes a plurality of thermally conductive laminations  434  that are substantially similar to laminations  234  (shown in  FIG. 10 ). In this alternative embodiment, the axial dimension (thickness) of teeth portion laminations  432  is larger than an axial dimension (thickness) of yoke portion laminations  434 . This alternative embodiment facilitates a uniform temperature distribution within and effective heat removal from teeth portion  402 . Moreover, in this alternative embodiment, laminations  432  and  434  within teeth portion  402  and yoke portion  404 , respectively, have substantially similar axial dimensions, i.e., thicknesses. Furthermore, in this alternative embodiment, the thicknesses of laminations  432  are substantially uniform within core portion  400 , i.e., a substantially uniform thickness distribution of laminations  432  is attained within core portion  400  wherein the thicknesses of each of laminations  432  are substantially similar. Similarly, in the exemplary embodiment, the thicknesses of laminations  434  are substantially uniform within core portion  400 , i.e., a substantially uniform thickness distribution of laminations  434  is attained within core portion  400  wherein the thicknesses of each of laminations  434  are substantially similar. Alternatively, a distribution of differing predetermined thicknesses of laminations  432  and  434  may be used to facilitate attaining predetermined parameters that facilitate operation of motor  104 . This alternative distribution may include a uniform or non-uniform distribution of varying thicknesses. 
         [0060]      FIG. 13  is a cross-sectional schematic of a plurality of alternative thermally conductive stator laminations  532  and  534  with a varying axial pitch that may be used with electric motor  104  (shown in  FIG. 2 ). Rotor axis of rotation  132  is illustrated for perspective. Alternative stator core  500  includes alternative teeth portion  502  and alternative yoke portion  504 . Teeth portion  502  includes a plurality of magnetic laminations  530  that are substantially similar to laminations  230  (shown in  FIG. 10 ) in the exemplary embodiment with the exception that laminations  530  are configured to receive a plurality of alternative thermally conductive laminations  532 . Laminations  532  are substantially similar to laminations  232  (shown in  FIG. 10 ) with the exception that laminations  532  are interspersed within stator teeth portion  502  wherein there are varied axial lengths between each of laminations  532 . Yoke portion  504  includes a plurality of thermally conductive laminations  534  that are substantially similar to laminations  234  (shown in  FIG. 10 ) with the exception that laminations  534  are interspersed within stator toke portion  504  wherein there are varied axial lengths between each of laminations  534 . The axial dimensions between laminations  532  within teeth portion  502  and laminations  534  within yoke portion  504  are substantially similar such that thermal communication between laminations  532  and  534  is facilitated. This alternative embodiment facilitates a uniform temperature distribution within and effective heat removal from core portion  500 . Moreover, in this alternative embodiment, laminations  532  and  534  within teeth portion  502  and yoke portion  504 , respectively, have substantially similar axial dimensions, i.e., thicknesses. Furthermore, in this alternative embodiment, the thicknesses of laminations  532  are substantially uniform within core portion  500 , i.e., a substantially uniform thickness distribution of laminations  532  is attained within core portion  500  wherein the thicknesses of each of laminations  532  are substantially similar. Similarly, in the exemplary embodiment, the thicknesses of laminations  534  are substantially uniform within core portion  500 , i.e., a substantially uniform thickness distribution of laminations  534  is attained within core portion  500  wherein the thicknesses of each of laminations  534  are substantially similar. Alternatively, a distribution of differing predetermined thicknesses of laminations  532  and  534  may be used to facilitate attaining predetermined parameters that facilitate operation of motor  104 . This alternative distribution may include a uniform or non-uniform distribution of varying thicknesses. 
         [0061]    With reference to  FIG. 2 , stator  122  also includes a plurality of armature windings of which a plurality of end windings, or end turn, portions  236  and  238  are illustrated. Specifically, stator core portion  200  includes a plurality of outboard and inboard winding end turn portions  236  and  238 , respectively. In the exemplary embodiment, a plurality of end turn support members  240  are secured to flared portions radially outer surfaces  164  and  168  such that radial and axial support of winding end turn portions  236  and  238  are facilitated. Alternatively, any number of members  240  including, but not being limited to none, may be used. Members  240  may be fabricated of any materials that have properties that include, but are not limited to those that facilitate material and operational compatibility with surfaces  164  and  168  and winding end turn portions  236  and  238  material properties as well as facilitate attaining predetermined operational parameters associated with motor  104 . 
         [0062]      FIG. 14  is a cross-sectional schematic view of a plurality of exemplary armature slot outer and inner windings  242  and  244 , respectively, that may be used with electric motor  104 . Rotor portion  140 , rotor axis of rotation  132  and yoke portion  204  are illustrated for perspective.  FIG. 15  is a skewed axial schematic of stator teeth portion  202  coupled to stator enclosure center portion  152  (shown in  FIG. 3 ) that may be used with electric motor  104 . Rotor axis of rotation  132  and flared enclosure portions  158  and  160  are illustrated in  FIG. 15  for perspective. Teeth portion  202  receives a plurality of armature slot outer and inner windings  242  and  244 , respectively, within slots  208 . Windings  242  are positioned in a radially outer portion of slots  208 . Windings  244  are positioned in a radially inner portion of slots  208 . Winding end turns  236  and  238  are electrically coupled to and extend axially outward from windings  242  and  244  and windings  242  and  244  and end turns  236  and  238  form one coil. In this configuration, a radially winding  244  of one coil is positioned radially inward of a radially outer winding  242  of another coil within slot  208 . Alternatively, any number of and any configuration of windings may be used. In the exemplary embodiment, windings  242  and  244  and end turn portions  236  and  238  are electrically conductive bars fabricated with materials, apparatus and methods known in the art. Alternatively, windings  242  and  244  and end turn portions  236  and  238  may be, but not be limited to electrically conductive cables. Positioning windings  242  and  244  within slots  208  prior to enclosing teeth portion  202  within yoke portion  204  facilitates an efficiency of assembly and facilitates mitigating a potential for distorting windings  242  and  244 . 
         [0063]      FIG. 16  is a cross-sectional axial schematic view of plurality of exemplary armature windings  242  and  244  that may be used with electric motor  104  (shown in  FIG. 2 ). Rotor axis of rotation  132  and enclosure portion  152  are illustrated for perspective. Teeth portion  202  is illustrated with all of windings  242  and  244  positioned within slots  208  between teeth  206  and end turn portions  236  (and  238 ) extending therefrom. Windings  242  and  244  and end turn portions  236  (and  238 ) are illustrated as substantially transparent and enclosure flared portions  158  (and  160 ) (shown in  FIG. 15 ) are omitted to facilitate perspective. 
         [0064]      FIG. 17  is a cross-sectional axial schematic view of a plurality of yoke portion segments  214  that are coupled over plurality of armature windings  242  and  244  to form exemplary stator core portion  200  that may be used with electric motor  104  (shown in  FIG. 2 ). Rotor axis of rotation  132  and enclosure portion  152  are illustrated and enclosure flared portions  158  (and  160 ) (shown in  FIG. 15 ) are omitted for perspective. Teeth portion  202  is illustrated with all of windings  242  and  244  positioned within slots  208  between teeth  206  and end turn portions  236  (and  238 ) extending therefrom. Teeth portion  202  is further illustrated as being positioned within first of yoke sections  214 . End turns portions  236  (and  238 ) extend axially and flare radially outward from teeth portion  202  and are illustrated as partially obscuring lower yoke section  214 . In the exemplary embodiment, upper yoke section  214  is positioned over teeth portion  202  and windings  242  and  244  and coupled to lower yoke section  214  at mating surfaces  216  as described above. Moreover, assembling yoke portion  204  in this manner facilitates mitigating disturbing or distorting armature windings  242  and  244  as well as end turn portions  236  and  238 . 
         [0065]      FIG. 18  is a skewed axial schematic view of exemplary pressure vessel  105  that may be used with electric motor  104  (shown in  FIG. 2 ). Rotor axis of rotation  132  is illustrated for perspective.  FIG. 18  is referenced in conjunction with  FIG. 2  for discussion of pressure vessel  105 . Pressure vessel  105  includes a substantially cylindrical radially outer surface  246 , a radially inner surface  248 , and a plurality of external fins  250 . Fins  250  are fixedly coupled to outer surface  246 . Pressure vessel  105  further includes a plurality of substantially toroidal end walls  251  positioned at axially opposing ends of pressure vessel  105  that extend radially inward from inner surface  248 . 
         [0066]    In the exemplary embodiment, fins  250  and at least one end wall  251  are fabricated integrally with pressure vessel  105  via methods that include, but are not limited to forging and casting. Alternatively, fins  250  end walls  251  may be fabricated independently and coupled to pressure vessel outer surface  246  and inner surface, respectively, via methods that include, but are not limited to welding and brazing. Fins  250  include predetermined axial and radial dimensions that facilitate heat transfer from motor  104 . End walls  251  include predetermined radial dimensions to facilitate defining an annular passage  254 . Opening  254  is sized to facilitate receipt of rotor spindle portion  142  and seal  137 . Parameters associated with the materials used to fabricate pressure vessel  105  include, but are not limited to having sufficient heat transfer properties to facilitate conductive heat transfer, and having sufficient strength and corrosion resistance to mitigate pressure vessel  105  distortion and corrosion during operation. Materials that may be used to fabricate pressure vessel  105  include, but are not limited to Incoloy 925®, Inconel 718®, and stainless steel. 
         [0067]    In the exemplary embodiment, pressure vessel  105  is substantially cylindrical. Alternatively, pressure vessel  105  and its associated components may be of any shape and/or configuration that attain predetermined operating parameters. Also, in the exemplary embodiment, the radial distance between surfaces  246  and  248 , i.e., the thickness of pressure vessel  105 , and the materials of fabrication of pressure vessel  105  are sufficient to facilitate tolerating operating parameters such as, but not being limited to external operating pressures and temperatures associated with the depth and body of water in which station  100  is submerged as well as the properties of the fluid being transported. 
         [0068]      FIG. 19  is an axial schematic view of exemplary pressure vessel  105  that may be used with electric motor  104 . Rotor axis of rotation  132 , enclosure center portion  152 , teeth portion  202 , and yoke portion  204  are illustrated and walls  251  are omitted for clarity and perspective.  FIG. 19  and  FIG. 2  are referenced together to further discuss pressure vessel  105 . In the exemplary embodiment, pressure vessel inner surface  248  is coupled to yoke portion outer surface  220  in thermal communication such that conductive heat transfer from yoke portion  204  to pressure vessel  105  is facilitated. Methods of coupling surface  248  to surface  220  may include, but not be limited a pressurized interference fit that includes, but is not limited to a thermal shrink fit and/or a hydraulic shrink fit such that a preloaded low tolerance fit is attained. To further couple surface  248  to surface  220 , a seam defined at the fit regions by surface  248  and surface  220  may be sealed by methods that include, but are not limited to welding, brazing, adhesive bonding and sintering. The interference fit of pressure vessel  105  to yoke portion  204  facilitates securing teeth portion  202  between yoke portion  204  and enclosure  150 . 
         [0069]    In reference to  FIG. 2 , a portion of each of end walls  251  is coupled to an axially outermost portion of enclosure flared portions  158  and  160  to form substantially toroidal stator compartment  172 . Compartment  172  substantially isolates stator core  200  from the transport fluid. Compartment  172  may be further described as a plurality of portions. A substantially annular center portion  260  of compartment  172  is defined between enclosure center portion radially outer surface  156  and a portion of pressure vessel radially inner surface  248  and houses stator core portion  200 . An outboard end turn portion  262  is defined between a portion of center portion radially outer surface  156 , flared portion radially outer surface  164 , end wall  252 , a portion of pressure vessel radially inner surface  248  and axially outboard surfaces of core  200 . Portion  262  houses stator end turn portion  236 . An inboard end turn portion  264  is defined between a portion of center portion radially outer surface  156 , flared portion radially outer surface  168 , end wall  252 , a portion of pressure vessel radially inner surface  248  and axially inboard surfaces of core  200 . Portion  264  houses stator end turn portion  238 . 
         [0070]    In the exemplary embodiment, compartment  200  is filled with a dielectric fluid, for example, but not being limited to transformer oil. The dielectric fluid has properties that include, but are not limited to facilitating convective and conductive heat transfer and mitigating potential for electrical arc discharges within compartment  200 . 
         [0071]    With reference to  FIGS. 1 and 2 , in operation, the fluid being transported by compressor  102  (shown in  FIG. 1 ) may also be used to facilitate cooling of motor  104 . Prior to electrically powering stator  122  and starting motor  104  a volume  106  within pressure vessel  105  that excludes stator compartment  172  and includes the volume defined by motor end cover assembly  118  and end walls  252  is filled with transport fluid at a predetermined rate of pressurization and attains a predetermined pressure that may include, but not be limited to a pressure substantially similar to that of inlet pipeline  110 . As volume  106  pressure is changed, stator enclosure  172  pressure may be changed as well using methods and apparatus known in the art to facilitate mitigating pressure differentials between volume  105  and stator compartment  172 . 
         [0072]    Once motor  104  is powered and rotor  120  is rotating, heat losses and fluid friction losses of transport fluid may generate a temperature increase of rotor portion  140 . Transport fluid in flow and thermal communication with rotor assembly  120 , and in particular, portion  140  may facilitate heat transfer from rotor portion  140  to other components that include, but are not limited to motor end cover assembly  118  and enclosure portions  152 ,  158  and  160  for subsequent heat transfer to an outside environment and the dielectric fluid within compartment  172 , respectively. 
         [0073]    Also, during operation of motor  104 , wherein stator  122  is electrically powered, heat losses within stator end turn portion  236  and  238  typically increase the temperature of the associated components. Heat losses within portions  236  and  238  are substantially conductively transferred to the dielectric fluid. Convective fluid flow within compartment portions  262  and  264  is induced by the difference in dielectric fluid temperatures between dielectric fluid in contact with stator end turn portions  236  and  238  and dielectric fluid not in contact with portions  236  and  238 . Heat is subsequently transferred to pressure vessel  105 . 
         [0074]    Further, during operation of motor  104 , wherein stator  122  is electrically powered, heat losses within stator teeth portion  202  via armature windings  242  and  244  (shown in  FIG. 14 ) are substantially collected and channeled to pressure vessel  105  via conductive heat transfer of laminations  232  and  234 . 
         [0075]    As discussed above, during operation, pressure vessel  105  tends to receive a predetermined heat energy at a predetermined rate of heat transfer from motor  104  components. The environment surrounding pressure vessel  105  typically has a lower temperature than the environment within pressure vessel  105 . Therefore, surface  246  and fins  250  are typically cooler than surface  248  and heat transfer from motor  104  to the environment external to pressure vessel  105  is facilitated. 
         [0076]    The compressing station described herein facilitates transporting natural gas through a pipeline. More specifically, the compressing station assembly includes a compressing device coupled to a super-synchronous electric motor. Super-synchronous electric motors facilitate elimination of additional components, for example, gearboxes, thereby facilitating a smaller foot print of the station as well as eliminating the associated gearbox maintenance costs. Such motors also facilitate station operation at higher energy densities and at higher speeds, thereby further reducing the foot print, as well as facilitating the advantages of higher efficiency due to the capability to operate at higher speeds. As a result, the operating efficiency of compressing stations may be increased and the stations&#39; capital and maintenance costs may be reduced. 
         [0077]    The methods and apparatus for transporting a fluid within a pipeline described herein facilitates operation of a fluid transport station. More specifically, the motor as described above facilitates a more robust fluid transport station configuration. Such motor configuration also facilitates efficiency, reliability, and reduced maintenance costs and fluid transport station outages. 
         [0078]    Exemplary embodiments of motors as associated with fluid transport station are described above in detail. The methods, apparatus and systems are not limited to the specific embodiments described herein nor to the specific illustrated motors and fluid transport station. 
         [0079]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.