Abstract:
A synchronous reluctance machine that has a stator and a rotor shaft operationally disposed within the confines of the stator. Laminations are axially stacked to form boat shaped segments. A plurality of selected boat shaped segments form a selected number of rotor poles about the rotor shaft and a plurality of support bars disposed intermittently between the boat shaped segments. Each segment of lamination is boat shaped with angular acuity facing towards the stator.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     A synchronous machine has a stator and a rotor supported in the inner periphery of the stator, is capable of being locally excited and is structurally the same as the stator of a common induction machine. Generally, the synchronous reluctance machine is well known as a motor, which is simply structured and does not need electric current channels or permanent magnets in the rotor. For example, the conventional induction machine comprises a machine body serving as a casing, a stator arranged along an inner circumferential surface of the machine body and an AC squirrel cage rotor rotatably arranged based on a rotational shaft at the center of the stator. The stator is formed of a lamination structure of a plurality of silicon steel and is provided with a plurality of teeth therein. A plurality of slots are formed between the teeth with a certain interval and the coil is wound on the teeth through the slots.  
         [0002]     The synchronous reluctance rotor generally includes a plurality of rotor sections formed of alternating magnetic and non-magnetic laminations secured to a unitary core. The core has a central axial bore for receiving a shaft. The laminations are inserted between radially extending arms of the core that are formed with a smooth, arcuate recess therebetween. The laminations are secured in the recesses by means of radial fasteners that secure radially opposing rotor sections to the core. The rotor sections are also secured together by end caps and radial fasteners. The end caps are cup-shaped members with an axially extending outer rim that is disposed about the outermost periphery of the laminations. The radial fasteners extend through the end caps and core to secure the end caps to the rotor. The rotor laminations may also be bonded to one with another and to the core using an epoxy or other adhesive material.  
         [0003]     Existing synchronous reluctance machines are mechanically and thermally limited due to the use of “boat” shaped laminations, stacked radially for the rotor. Traditionally, the synchronous reluctance machines have a rotor shaft that has been machined to receive the boat shaped laminations stacked radially along the rotor shaft. The boat shaped lamination poles are then bolted to the rotor shaft. This construction limits the rotor dimensions for high-speed applications and inherently has significant core losses. Attempts in the past to remedy this problem have been to select alternate machine topology and not to address the problem directly.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0004]     The disclosed technology is a synchronous reluctance machine that has stator and a rotor shaft operationally disposed within the confines of the stator. A plurality of selected boat shaped segments laminated axially forms a selected number of rotor poles about the rotor shaft. A network of support bars support the rotor pole segments radially. Each of the support bars is of sufficient size to carry the centripetal loading of the segments located radially within.  
         [0005]     The above described and other features are exemplified by the following figures and detailed description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     Referring now to the figures wherein the like elements are numbered alike:  
         [0007]      FIG. 1  illustrates an end view diagram of an exemplary embodiment of a synchronous reluctance machine,  
         [0008]      FIG. 2  illustrates an end view diagram of a pole of a rotor of  FIG. 1 ,  
         [0009]      FIG. 3  illustrates a perspective view diagram of a plurality of pole segments of  FIG. 2 ,  
         [0010]      FIG. 4  illustrates an end view diagram of selective planar lamination shapes of a rotor pole,  
         [0011]      FIG. 5  illustrates a perspective view of an arbitrary length of the support bar structure of  FIG. 1 ,  
         [0012]      FIG. 6  illustrates an end view of an inside-out synchronous reluctance machine,  
         [0013]      FIG. 7  illustrates an end view of a double-sided synchronous reluctance machine,  
         [0014]      FIG. 8  illustrates an end view of a double-sided synchronous reluctance machine alternate embodiment of  FIG. 7 . 
     
    
     DETAILED DESCRIPTION  
       [0015]     The disclosed technology is a synchronous reluctance machine  10 ,  FIG. 1  that has a selectively shaped rotor  12  and a stator  11 . The stator  11  has a plurality of slots sized to receive armature windings. The selectively shaped rotor  12  of the synchronous reluctance machine  10  is configured in  FIG. 1 , as a four-pole machine  14 ,  15 ,  16  and  17 . It is understood the synchronous reluctance machine  10  may, if desired, be configured with as many poles as desired. The configuration illustrated in  FIG. 1 , is for illustration purposes only. Each individual pole of the synchronous reluctance machine  10 ,  FIG. 1 , is of identical construction. For example, synchronous reluctance machine  10 ,  FIG. 1 , has four poles but for design reasons or performance requirements the synchronous reluctance machine may have six identical poles.  
         [0016]     The exemplary pole  14 ,  FIG. 2 , is constructed from a plurality of axially positioned boat shaped laminated segments  18 ,  19 ,  20 ,  21 ,  22 ,  23 ,  24 ,  25 ,  26 ,  27 ,  28 ,  29  and  39 . The laminated segments  18  to  29  and  39  are only exemplary. The number of laminated segments may, if desired, be any number depending on the design criteria of the synchronous reluctance machine. The laminated segments  18  to  29  and  39  may, if desired, be silicon steel or any other convenient, preferably magnetic, material. The number of laminated segments  18  to  29  and  39  shown in the example is twelve but could be any other desired number. Each laminated segment is separated from the subsequent laminated segment by a spacer or end bar  30 . The end bars  30  may, if desired, be any convenient shape or size to separate the laminated segments. Depending on the design criteria of the synchronous reluctance machine the end bars  30  may be of varying size within the rotor pole structure. For example, the end bars  30  of exemplary pole  14  are all the same size, have an elongated shape and traverse the axial length of each associated boat shaped structure. The end bars  30  are manufactured from any convenient non-ferromagnetic material that can offer high strength at elevated temperatures like Inconel, AM 350 or 17-4PH.  
         [0017]     The laminated segments  18  to  29  and  39 ,  FIG. 2 , are sufficiently separated to receive a forced or non-forced cooling gas or fluid. Examples of a cooling gas are air, nitrogen or any other type of gas. The exemplary gas may, if desired, be refrigerated or super cooled. Alternate liquid coolants may also be considered if amenable to the operating environment. The rotor may operate at a temperature different than that of the stator. The temperature range over which the rotor may be operated need only be limited by the materials used in its construction. As the synchronous reluctance rotor topology does not require the use of temperature restricted materials such as copper or electrical insulation it may be operated across a broad range of temperatures.  
         [0018]     Each of the axially positioned boat shaped laminated segment  18  to  29  and  39  have two angled portions to form a boat shape. The angled sections of each laminated segment  18  to  29  and  39  are separated from the subsequent angled section by an angled spacer bar  31 . The angled spacer bar  31  may, if desired, have any convenient angle depending on the number of poles and the physical size of the synchronous reluctance machine  10 . An example of an angled spacer bar  31  is a bar having an angle of 45 degrees. The angled spacer bars  31  may, if desired, be fabricated from the same or different material as the end bars  30 . The end cap bar  32  is sized to fit in the top most laminated segment. In this particular discussion the top most laminated segment is  39 . The end cap bar  32  serves as a support bar for the top most laminated segment  39 . The angled spacer bars  31  and the end bars  30  act in concert to support each of the laminated segments  18  to  29  and  39 . Further, the angled spacer bars  31  and the end bars  30  create gap or free space between each of the laminated segments  18  to  29  and  39 . This gap allows the cooling gas to freely move between the segments and remove heat from the respective pole.  
         [0019]     Rotor pole  14 ,  FIG. 3  may, if desired, contain three sections  40 ,  41  and  42 . Any number of sections may form rotor pole  14 .  FIG. 3  illustrates three sections. This is for illustration purposes only and does not limit the disclosed technology. All of the poles  14 ,  15 ,  16  and  17  of the synchronous reluctance machine  10  preferably have the same number of sections. For example, if pole  14  had four sections then poles  15 ,  16  and  17  would have four sections. The rotor pole  14 , section  40  is separated from section  41  by an intermediate support disc  43 . Section  41  is separated from section  42  by intermediate disc  44 . If the number of sections were increased to form any given rotor pole then the number of intermediate discs would increase proportionally. The top surface  45  of the section  40  is rounded and smooth to conform to the inner portion of stator  11 .  
         [0020]     Each rotor pole  14 ,  15 ,  16  and  17  is held in place by an end cap or end flange. The end flange  46  is illustrated in  FIG. 3  adjacent to section  42 . For any given pole there are only two end flanges that hold laminated segments  18  to  29  and  39 , end bars  30 , intermediate support discs  43 - 44  and angled spacer bars  31  in place. The end flange  46  has one surface machined to fit the end portions of the laminated segments  18  to  29  and  39 , end bars  30  and angle spacer bars  31 . A portion of an individual end flange  46  is affixed to the rotor shaft  59 ,  FIG. 1 . In total for each pole  14 ,  15 ,  16  and  17  there are two end flanges with a portion of each connected to the rotor shaft  59 . All of the poles share round end flanges.  
         [0021]     The network of support bars supports the rotor pole segments radially. The support bars are the end bar  30 , angled spacer bar  31 , end cap bar  32  and intermediate disc  44 .  FIG. 5 . The support bars, in concert are the support for the laminated segments  18  to  29  and  39  structure and provide a web of open spaces between the laminated segments. The open spaces between the laminated segments are available for the flow of coolant that can be used to regulate the temperature of the rotor in high temperature environments.  
         [0022]     The boat shaped laminates  18  to  29  and  39 ,  FIG. 4  may, if desired, be any selected number depending on the design criteria for the machine. The spacing between the laminates is controlled by the size of end bar  30 . The size and shape of the end bars  30  are selectable depending on the design criteria of the synchronous reluctance machine. The physical geometry of the laminates may, if desired, be selectable. Examples of selectable physical geometries of laminates are near parabolic shaped laminate  47 ,  FIG. 4  and the special shaped laminate  48 . The special shaped laminate  48  is substantially boat shaped with the end portions and the bottom portion enlarged. In each case the laminate is designed to meet certain design criteria and the designer of the synchronous reluctance machine  10  may, if desired, mix or match and vary the size of the spacer bars to meet selected design criteria. As the physical geometries of the laminates change so do the size and shape of the end bars  30 , intermediate disc  44  and angled spacer bars  31  to accommodate the size and shape of the laminates. The gap between the laminated segments may, if desired, vary to accommodate a larger volume of coolant. If the gap between the laminates changes their associated end bars, intermediate discs  44  and angled spacer bars  31  change accordingly.  
         [0023]     As delineated above the synchronous reluctance machine  10  has axially stacked laminations  18  to  29  and  39 , which significantly reduce the core losses. Each of the lamination segments is “locally” supported by end bars  30 , intermediate discs  43  and  44 , angled spacer blocks  31  and end cap bar  32  so that its mechanical load is not wholly transferred to the next one. This makes the rotor more robust and allows for higher speed and larger diameter designs. Also, intermediate placed discs  43  and  44  support the lamination sections  40 ,  41  and  42  axially. These bars with the spacing among the lamination segments and the local support structure provide a controlled passage for cooling fluid to remove any rotor losses in a very efficient manner.  
         [0024]     In operation: The rotor shaft  59  along with poles  14 ,  15 ,  16  and  17  containing the laminated segments  18  to  29  and  39  are rotatively disposed to the rotor which is supported by the inner peripheral surface of the stator  11  casing. Electrical AC power is supplied to the windings of the stator  11  and the rotor begins to rotate. A gas or fluid may, if desired, be forced or non-forced between and around the laminated segments  18  to  29  and  39  thereby cooling the laminated segments.  
         [0025]     An alternate embodiment of the disclosed technology may also take the form commonly referred to as the “inside-out” configuration  51 ,  FIG. 6 . In such a configuration, the axial laminations may form boat shaped segments radially and the assembly of segments may be located radially outside of the stator  53 . The stator  53  may then contain a plurality of windings and slots and may be located inside of the rotor  54 .  
         [0026]     Another embodiment of the disclosed technology may be applied in such a way that the “inside-out” configuration is used to provide a double-sided machine  52 ,  FIG. 7 . The axially stacked laminations  60  can be used to form radially spaced segments that occupy space between an inner  55  and an outer  56  stator assembly. Conversely, a set of lamination segments  57 ,  FIG. 8  may be assembled for rotating a structure radially inside the stator  58  structure while other lamination segments  60  are positioned radially outside the stator  58 .  
         [0027]     While the disclosed technology has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosed technology. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosed technology without departing from the essential scope thereof. Therefore, it is intended that the disclosed technology not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosed technology, but that the disclosed technology will include all embodiments falling with the scope of the appended claims.