Abstract:
In accordance with certain embodiments, the present invention provides a magnetizing system. This system includes a guide channel that is configured to receive a ferromagnetic element. When in this channel, a magnetic field source of the system is operable to magnetize the ferromagnetic element. Also, the exemplary system includes an actuation mechanism that drives the ferromagnetic element through the guide channel. Because a positioning mechanism of the system has aligned the guide channel with a slot of an electromagnetic machine component, the ferromagnetic element is routed through the channel and into the slot.

Description:
BACKGROUND  
       [0001]     This section is intended to introduce the reader to various aspects of art that may be related to aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.  
         [0002]     In industry, electromagnetic machines are often employed to generate power or to drive machine elements. For example, generators are designed to translate harnessed kinetic energy into electrical power, while electrical motors take advantage of electromagnetic relationships to translate electrical power into motion. As one particular application, generators can be found in wind turbine structures, which harness wind energy into electrical power. Advantageously, wind turbines produce electrical power in a virtually pollution-free manner, making them ecologically desirable.  
         [0003]     Such generators traditionally include a freely rotating rotor that is surrounded by a stationary stator. In the case of wind turbines, the fans blades are mechanically coupled to the rotor. Thus, induced rotation of the blades of the wind turbine by wind causes rotation of the rotor as well. Because the rotor is appropriately magnetized (i.e., provides magnetic fields of varying polarity), rotating magnetic fields are provided by the rotation of the rotor. In turn, the rotating magnetic fields induce an electrical current in stator windings of the stator assembly, the current then being harnessed for downstream use.  
         [0004]     In wind turbines, particularly utility class wind turbines, the generators employed can have relatively large diameters, four to five meters, for instance. Moreover, to more efficiently generate high-Gauss electromagnetic fields, rotors having magnetic poles formed of what are commonly known as “rare earth magnets,” e.g., Neodymium-Iron-Boron (NdFeB) and Samarium Cobalt (SmCo), are employed. Advantageously, these rare earth magnets have a high-energy product, forty megaGauss Oersted (GOe), for instance. However, a rare earth magnet must be magnetized—by placing the rare earth magnet in a strong magnetizing—and assembled onto the rotor.  
         [0005]     Unfortunately, magnetizing and assembling a magnet pole formed of such rare earth magnets with respect to a rotor can be a relatively difficult task. For example, if the magnet pole is magnetized prior to assembly onto the rotor, the operator may find it unwieldy to manage, because the magnetic field of the pole would interact with various other ferromagnetic structures on the electrical machine and even other magnet poles, for instance. Moreover, even after the magnet pole is mounted with respect to the rotor, difficulties may arise in assembling the magnetized rotor with respect to the stator and the remainder of the generator structure. As an alternative, past assembly techniques have included magnetization of the magnet pole after it has been assembled onto the rotor, and, in certain cases, after the rotor has been assembled with respect to the remainder of the generator. Unfortunately, the systems employed for such in situ magnetization are relatively large and bulky, increasing the costs and times for assembly.  
         [0006]     Therefore, there exists the need for improved systems and methods for electromagnetic machine assembly.  
       BRIEF DESCRIPTION  
       [0007]     Certain aspects commensurate in scope with the originally claimed invention are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.  
         [0008]     In accordance with certain embodiments, the present invention provides a magnetizing system. This system includes a guide channel that is configured to receive a magnet pole. When in this channel, a magnetic field source of the system is operable to magnetize the ferromagnetic element. Also, the exemplary system includes an actuation mechanism that drives the ferromagnetic element through the guide channel. Because a positioning mechanism of the system has aligned the guide channel with a slot of an electromagnetic machine component, the ferromagnetic element is routed through the channel and into the slot. 
     
    
     DRAWINGS  
       [0009]     These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:  
         [0010]      FIG. 1  is a diagrammatic representation of a wind turbine generator system, in accordance with certain aspects of the present invention;  
         [0011]      FIG. 2  is a diagrammatic, cross-sectional view of a generator, in accordance with certain aspects of the present invention;  
         [0012]      FIG. 3  is a diagrammatic representation of a system for assembly of an electromagnetic machine, in accordance with certain aspects of the present invention;  
         [0013]      FIG. 4  is an illustration of a magnetizing device, in accordance with certain aspects of the present invention;  
         [0014]      FIGS. 5, 6 , and  7  are, respectively, illustrations of a magnetizing device during various stages of operation, in accordance with various aspect of the present invention; and  
         [0015]      FIG. 8  is a flow chart representative of a method for assembly of an electromagnetic machine, in accordance with certain aspects of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0016]     One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliant with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.  
         [0017]     As discussed in detail below, the present invention, in accordance with certain embodiments, provides apparatus and methods for the assembly of electromagnetic machines. For example, the following discussion describes magnetizing systems and methods that facilitate concurrent magnetization and insertion of a magnet pole into a rotor of a permanent magnet generator. However, despite the fact that the following discussion focuses on generator assemblies, particularly permanent magnet rotors of such generators, the present invention may be applicable to a vast number of electromagnetic machines in which the assembly of magnetic components is a concern, including motor assemblies, and the like.  
         [0018]     Turning to the figures,  FIG. 1  illustrates a wind turbine power generation system  10 , in accordance with certain aspects of the present invention. The system  10  includes a wind turbine  12 , which is part of a larger wind farm. The wind turbine  12  has a plurality of blades  14  that harness wind energy into rotational motion of the blades  14 . This rotation is mechanically transferred to a generator  16  disposed in the nacelle  18  of the wind turbine  12 . As will be appreciated by those of ordinary skill in the art, the generator  16  has a permanent magnet rotor  20  surrounded by a stator  22 , and the electromagnetic relationship between the rotor  20  and the stator  22  generates electrical current in the stator  22  due to rotation of the rotor  20 . This electrical current is routed to signal transmission circuitry  24 , at which point it is conditioned and forwarded to a power grid  26  for distribution.  
         [0019]      FIG. 2  is a cross-sectional illustration of an exemplary generator  16 , which, for the purposes of this discussion, has been simplified and does not illustrate various components that are commonly appreciated by those of ordinary skill in the art. As illustrated, a shaft  28  extends through the rotor  20  and is supported by a plurality of bearings assemblies  30 . Via the bearing assemblies  30 , the rotor  20  is free to rotate with respect to the stationary stator  22 . Advantageously, as will be appreciated by those of ordinary skill in the art, “permanently magnetized” magnet poles  32  mounted on the surface  34  of the rotor  20  facilitate translation of the rotor&#39;s  20  rotation into an induced voltage in the stator windings  36  of the stator  22 . This configuration is commonly referred to as a surface-mounted permanent magnet rotor. This invention also pertains to electric machines wherein the permanent magnet poles  32  are mounted in the interior of the rotor. Thus, “surface,” as usual herein, applies to both externally located surfaces as well as interior surfaces.  
         [0020]     The angular location of the magnet pole  32  on the rotor  20  determines the pole&#39;s  32  polarity. Thus, because of the variances in polarity, different magnetic fields are present. In turn, the rotation of the rotor  20 , which carries the magnet poles  32 , produces a changing magnetic field that, as is well known, induces electrical voltage in the stator windings  36 .  
         [0021]     To effectuate the production of good levels of electrical power, the exemplary magnetic poles  32  comprise rare earth magnet materials, such as Neodymium-Iron-Boron (NdFeB) and/or Samarium Cobalt (SmCo). However, it is worth noting that the magnet poles  32  may be formed of any number of hard ferromagnetic materials. Additionally, these exemplary magnet poles  32  can comprise a single piece that is mounted on the rotor surface  34 , or may be segmented as is illustrated. Advantageously, segmented poles  32  simplify installation, because they are smaller and less difficult to manage in comparison to single pole pieces. Moreover, segmented poles are more resistant to “cracking” during a generator&#39;s life, for instance.  
         [0022]      FIG. 3  illustrates an assembly mechanism  38  for magnetizing and inserting magnet poles  32  into a rotor assembly. Although described in relation to a rotor, it is worth noting that the present assembly mechanism  38  affords benefits to any number scenarios related to the assembly and magnetization of magnetic components of electromagnetic machines. As discussed in detail below, the assembly mechanism  38  facilitates temporal proximity between the magnetization of the magnet pole  32  and the installation of the magnet pole  32  on to the appropriate location on the rotor surface  34  of the rotor  20 . Advantageously, the exemplary assembly mechanism  38  simplifies the assembly process and facilitates in situ installation, as also further discussed below.  
         [0023]     The assembly mechanism  38  includes a positioning structure  40  that aligns the assembly mechanism  38  with the appropriate rotor surface location  34  of the rotor  20 . This positioning can be effectuated by the movement of the rotor  20  with respect to the assembly mechanism  38 , movement of the assembly mechanism  38  with respect to the rotor  20 , or any combination thereof with respect to one answer. Thus, the positioning structure can include components that position the rotor  20 , the assembly mechanism  38 , or any combination thereof. Once appropriately positioned, as discussed in detail below, an unmagntized pole  32  is placed into the body or chassis of a magnetizing device  42 . Specifically, this device  42  both guides the magnet pole  32  onto the rotor surface location  34  and, relatively concurrently, magnetizes the pole  32 . To insert the magnet pole  32  onto the rotor surface location  34 , the assembly mechanism  38  includes an actuation mechanism  44 , which can include hydraulic device  46 , for instance. Additionally, the magnetizing device  42  includes a magnetic field source, such as a coil  48 . Advantageously, the positioning structure  40 , the actuation mechanism  44 , the magnetizing coil  48 , among other components, are under the direction of a controller  50 . By way of example, the controller  50  may be a programmable logic circuit (PLC), a processor, among other kinds of devices. Communications with the controller  50 , and the exemplary assembly mechanism  38  as a whole, are effectuated by a user interface  52 , which allows a user to provide inputs to and receive information regarding the assembly mechanism  38  and the assembly process.  
         [0024]      FIG. 4  focuses on an exemplary magnetizing device  42 . This device  42  includes an oval-shaped body  54 —which includes a magnetizing coil and carries a pole piece—that has a guide channel  56  coupled thereto. Although illustrated as a separate piece, it is worth noting that the guide channel  56  may be integral with respect to the body  54 . The guide channel  56  is designed to receive a magnetic pole  32  and guide the pole  32  as it is driven toward the rotor surface location  
         [0025]     Accordingly, the guide channel  56  matches closely the dimensioning of the magnet pole  32 . In fact, the guide channel  56  can include an adjustment mechanism that allows expansion or retraction of the guide channel  56  to best match the width of the given magnet pole  32 . Advantageously, the exemplary guide channel  56  includes a tray  58 , disposed at the exit end of the guide channel  56 , that well facilitates transition of the magnet pole  32  onto the rotor surface location  34 , because it extends beyond the body  54 , as one reason. Furthermore, to assist movement of the pole  32  through the guide channel  56 , the channel  56  may include moving features, such as rollers, a conveyor system, protruding tracks to minimize contact area, and hence friction, between the pole and the channel, or a carrier mounted on telescoping rails, for example.  
         [0026]     The guide channel may be made from a ferromagnetic material such as iron. In particular the guide channel may have top and bottom plates that are made out of ferromagnetic material. The guide channel, therefore, acts as a keeper of the magnetic flux as the magnet is transferred from the magnetizing fixture to the rotor surface location. Because the magnet is in a keeper, the net force acting on it is small independent of structures, particularly the iron and hard magnetic material structures external to the channel. The magnet pole  32  can be guided into its final position on the rotor surface  34  with a minimum of force, and reducing the likelihood of the magnet accelerating as is enters the rotor surface.  
         [0027]     As discussed above, the exemplary magnetizing device  42  includes a magnetic field source, such as the coil winding  48 , that operates to magnetize the magnet pole  32  after it is positioned in the proper position in the channel  56 . The illustrated coil winding  48  can receive power from power source  57 . As will be appreciated by those of ordinary skill in the art, placing this magnetic field source  48  in proximity to the guide channel  56  facilitates magnetization of the magnet pole  32 , and subsequent handling of the magnetized pole  32 . And this magnetic field source may be placed at a number of locations with respect to the remainder of the device  42 , whether in the body  54  or in a mounting structure  60  that surrounds the body  54 , for example.  
         [0028]     Turning to  FIGS. 5, 6 , and  7 , these figures respectively illustrate the magnetizing device  42  during various stages of the installation of the magnet pole  32 . Also, the following discussion refers to  FIG. 8 , which is a flow chart of an exemplary method in accordance with the present technique. Beginning with  FIG. 5 , the magnetizing device  42  is illustrated at an initial stage. In this stage, the magnet pole  32 , which is not substantially magnetized, is placed into the input end of the guide channel  56 . This step is represented by block  70  of  FIG. 8 . Advantageously, the fact that the magnet pole  32  is not substantially magnetized at this point makes the pole  32  easier to manage, because its does not have a substantial magnetic field that interacts with other components of the generator  16 . Moreover, in this stage, the actuation mechanism, in this case the hydraulic arm  46 , is in a retracted position with respect to the guide channel  56 .  
         [0029]      FIG. 6  illustrates the magnetizing device  42  at an intermediate stage. (Portions of the mounting structure  60  have been deleted for clarity of discussion.) In this stage, the hydraulic arm  46  has been lowered into position with respect to the guide channel  56 . The hydraulic arm  46  is then actuated, causing the magnet pole  32 , which is captured in the guide charmel  56 , to traverse the guide channel  56 . Advantageously, the guide channel  56  directs the magnet pole  32  toward the appropriate rotor surface location  34 . These steps are represented by blocks  72  and  74  of  FIG. 8 . Also, during this stage, the magnetic field source (e.g., coil assembly  48 ) is energized, thus magnetizing the magnet pole  32 . As discussed above, the angular location of the magnet pole  32  in the rotor  20  determines the polarity of the applied magnetic field and, in turn, the polarity of the magnet pole  32 . This step is represented by block  76  of  FIG. 8 .  
         [0030]      FIG. 7  illustrates the magnetizing device  42  at its final stage. In this stage, the magnet pole  32  is driven through the guide channel  56  and the tray  52 , and into the appropriate rotor surface location  34 . This step is represented by block  74  of  FIG. 8 . Once the pole  32  is inserted, the positioning structure  40  is aligned with the next rotor surface location  34  to be filled, and the above-described process is repeated until all of the magnet poles have been inserted. These steps are represented by blocks  78  and  80  of  FIG. 8 .  
         [0031]     Advantageously, it is believed that the relative concurrency of the insertion and magnetization process facilitates a more simplified and cost effective installation in comparison to traditional techniques. In fact, it is believed that the present technique affords many benefits to in situ installation.  
         [0032]     While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.