Abstract:
A combination of a unique construction format, involving two sets of rotor and stator embodiments, working in co-operation with each other, in a unique fixed, direct-axis and quadrature-axis orientation, and with unique field-winding, back-EMF cancellation, connection schemes to substantially negate the field-winding harmonic currents in the field-winding excitation circuits, and provide for a substantially square-wave shaped, open-terminal, armature output-voltage characteristic.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention is related to the field of art of the brushless, windingless rotor, variable reluctance, electromechanical alternators and motors having wound-field excitation. 
         [0003]    2. Background Information and Prior Art 
         [0004]    The invention disclosed herein represents a significant improvement to, and an addition of new matter to the subject matter of the U.S. Pat. No. 5,146,127 to Smith, in the context of an inventive combination. The improvement by the inventive combination and the new matter disclosed are primarily focused on the potential applications of the technologies of the referenced Smith patent, in the areas of direct-current alternator products, single-phase and three-phase power alternators having alternating-current (AC), field-modulated excitation, as well as, electronically commutated (EC), direct-current, controlled drive motor products. 
         [0005]    The disclosure by the U.S. Pat. No. 5,146,127 to Smith did not provide for a means, nor method, to substantially negate the undesirable harmonics in the currents of the field excitation circuits, that are the result of the back electromotive force, or back-EMF, generated in the field windings by the varying magnetic field pole fluxes. This field current harmonic condition results in undesirable harmonic distortion in the induced armature, open-terminal, output voltage waveform. Furthermore, the harmonics in the field currents and the armature, open-terminal, output voltage, interactively reduce machine efficiency; reduce the quality of the armature output-voltage waveform from the desired square-wave form, and introduce undesirable operational torque characteristics. 
         [0006]    The means and methods disclosed herein, which consist of a combination of (1) a unique construction format for the rotor and stator embodiments, and (2) the connection schemes for the field windings, whereas, the combination is essential to substantially negate the aggregate back EMF of the field windings, to minimize the harmonic content of the field excitation currents, were not considered in the disclosure by Smith. 
         [0007]    In addition to the unique construction format and the unique connection schemes for the field excitation windings, which are disclosed in the inventive combination, there is still another significant improvement disclosed herein that would add new matter to the disclosure in U.S. Pat. No. 5,146,127 to Smith. That is, the aggregate inductance of the field excitation windings and circuits would be substantially constant in magnitude; complementing the efforts to reduce the harmonics in the currents and EMF waveforms in both the field windings and armature windings circuitry. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    Accordingly, one of the primary objectives of this invention and disclosure is to provide for brushless, windingless rotor, variable reluctance, electromechanical alternators with wound-field excitation; which are uniquely constructed to provide for an optimized, open-terminal, armature output EMF waveform that has substantially an alternating square wave characteristic. 
         [0009]    Another primary objective of this invention and disclosure is to provide for brushless, windingless rotor, variable reluctance, electromechanical alternators with wound-field excitation; which are uniquely constructed to provide for an excitation field current that can be optimized or maximized for the direct current component of harmonic content. 
         [0010]    Still another primary objective of this invention and disclosure is to provide for brushless, electronically commutated, windingless rotor, variable reluctance, electromechanical motors with wound-field excitation; which are uniquely constructed to optimize the direct-current component of the field control currents and armature output EMF waveform characteristic for optimal performance of operation. 
         [0011]    A more detailed primary objective of this invention and disclosure is to provide unique alternator and motor construction formats by means of a set of stator and rotor embodiments fixed in a quadrature-axis orientation, along with another set of stator and rotor embodiments fixed in a direct-axis orientation; working as a complementary combination on the same rotor shaft, in conjunction with unique field-winding connection schemes that use field-winding, back-EMF cancellation methods, to significantly reduce the harmonics in the field-winding excitation circuits, as well as, the associated harmonics that are generated in the armature windings as a result of the harmonic currents in the field windings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0012]    Thus, having presented the above general summary of this invention and disclosure, the following drawing figures are provided to further aid in the understanding of the preferred embodiment disclosed herein. 
           [0013]      FIG. 1  is a view of the rotor and stator embodiments of the preferred operational example, which illustrates one method to provide the direct-axis and quadrature-axis effect in the polyphase machine, by using a rotational (angular) shift in one of the rotor lamination embodiments. 
           [0014]      FIG. 2  is a view of the rotor and stator embodiments of the preferred operational example, which illustrates an alternative method to provide the direct-axis and quadrature-axis effect in the polyphase machine, by using a rotational (angular) shift in one of the stator lamination embodiments. 
           [0015]      FIG. 3  illustrates the relative positions of the salient rotor poles and salient stator poles when the rotor-stator set is in the direct-axis orientation. 
           [0016]      FIG. 4  illustrates the relative positions of the salient rotor poles and salient stator poles when the rotor-stator set is in the quadrature-axis orientation. 
           [0017]      FIG. 5  shows the pattern of locations for the field excitation windings and the armature windings, as located on the stator lamination embodiment. Also, shown is the pattern of the magnetic polarities of the field salient poles that are created by the field excitation currents in the field windings. 
           [0018]      FIG. 6  provides the labeling and nomenclature for the back-EMF generated by the field excitation windings, so that management of the winding polarities will result in the desired connection schemes. 
           [0019]      FIG. 7  illustrates the preferred connection scheme of the field excitation windings of the preferred operational example, which will provide the objective of producing field winding, back-EMF cancellation in the field excitation circuit. 
           [0020]      FIG. 8  illustrates the preferred connection scheme of the field excitation windings for the previous art, which did not provide for methods of field winding, back-EMF cancellation in the field excitation circuit. 
           [0021]      FIG. 9  provides vectorial polarity nomenclature to the back-EMF quantities of the field excitation windings, as an aid to properly connect these windings to achieve one of the primary objectives of field winding, back-EMF cancellation in the field excitation circuit. 
           [0022]      FIG. 10A  is a plot which illustrates a representative wave form and polarity of the back-EMF generated by the field winding having the indicated coil terminal numerals in the subject plot. Also, shown is a brief plot indicating the scale units of all the plots in  FIG. 10 ,  FIG. 11 , and  FIG. 12 . as the normalized (or, per unit) values of the back-EMF quantities versus the (rotational) radians of rotor movement. 
           [0023]      FIG. 10B  illustrates plots of representative wave forms of both opposing vectorial polarities of the back-EMF generated by the field winding as identified by the indicated coil terminal numerals. 
           [0024]      FIG. 10C  is a plot which illustrates a representative wave form and polarity of the aggregate (vectorial) sum of the back-EMF&#39;s generated by the two field coils as identified by the indicated field coil terminal numerals, shown in the connection scheme of  FIG. 9 . 
           [0025]      FIG. 11A  illustrates a representative wave form and polarity of the back-EMF generated by the field winding having the indicated field coil terminal numerals. 
           [0026]      FIG. 11B  illustrates plots of representative wave forms and both opposing (vectorial) polarities of the back-EMF generated by the field winding as identified by the indicated field coil terminal numerals. 
           [0027]      FIG. 11C  is a plot which illustrates a representative wave form and polarity of the aggregate (vectorial) sum of the back-EMF&#39;s generated by the two field windings as identified by the indicated field coil terminal numerals, shown in the connection scheme of  FIG. 9 . 
           [0028]      FIG. 12A  is a plot which illustrates a representative wave form and polarity of the aggregate (vectorial) sum of the back-EMF&#39;s generated by the two field windings as identified by the field coil terminal numerals, shown in the connection scheme of  FIG. 9 . 
           [0029]      FIG. 12B  is a plot which illustrates a representative wave form and polarity of the aggregate (vectorial) sum of the back-EMF&#39;s generated by the two field windings as identified by the field coil terminal numerals, shown in the connection scheme of  FIG. 9 . 
           [0030]      FIG. 12C  is a plot which illustrates a representative wave form of the aggregate (vectorial) sum of the back-EMF&#39;s generated by the four field windings as identified by the field coil terminal numerals, shown in the connection scheme of  FIG. 9  as the completing steps to provide for the back-EMF cancellation objective. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    For the purpose of promoting an understanding of this invention and disclosure, references will be made to the embodiments illustrated in the drawings, as the preferred operational example. It is intended that no limitation of the scope of this invention is being implied by the preferred operational example used herein, with any alterations, modifications, or derivatives of the illustrated embodiments and any application of the principles, features, and methods or processes within the spirit of the present invention and disclosure, and as illustrated herein and being contemplated, as occur to one skilled in the art to which this invention relates. 
         [0032]    Accordingly, with reference to  FIG. 3  and  FIG. 4 , there is illustrated in each drawing a set of stator  30  and rotor  20  embodiments, herein, referred to as laminations, lamination embodiments, lamination sets, or lamination stacks, for the four-pole machine that will be referred to throughout this description as an operational example. The illustration in  FIG. 3  displays a stator  30  lamination pattern as well as the rotor  20  lamination pattern. An assembled machine will typically involve a stack of each type of the illustrated stator  30  and rotor  20  laminations. In  FIG. 3  a set  10  of stator  30  and rotor  20  laminations are displayed in a direct-axis orientation. The scheme illustrated in  FIG. 4  displays a set  11  of stator  30  and rotor  20  laminations in a quadrature-axis orientation. The two stator  30  and rotor  20  lamination sets,  10  and  11 , of  FIG. 3  and  FIG. 4  must each maintain this special orientation when final assembly is complete. That is, one set  10  of stator  30  and rotor  20  laminations has to be in a direct-axis orientation when the other set  11  of stator  30  and rotor  20  laminations is in quadrature-axis orientation, and must maintain this angular association as the rotor shaft  40 , with the two rotor  20  lamination embodiments affixed, rotates within the machine. The general design patterns and scheme of the stator  30  laminations and the rotor  20  laminations in  FIG. 3  and  FIG. 4  are such that the salient stator poles  31 , herein referred to as salient stator poles, or stator poles, number in multiples of four; have even angular centerline spacing  32  around the stator  30  laminations, and are substantially equal in angular pole width  33 . The angular spacing  34  between the tips  36  of the stator poles  31  is substantially equal to the angular pole width  33 . Where as, the salient rotor poles  21 , herein referred to as salient rotor poles, or rotor poles, number one-half the number of stator poles  31  and have substantially the same angular pole width  33  as the stator poles  31 . The rotor poles  21  have an evenly spaced angular displacement  35  about the rotor  20  lamination embodiment. 
         [0033]    A set  10  of stator  30  and rotor  20  laminations in  FIG. 3  are assembled with a common rotor shaft  40 , along with a set  11  of stator  30  and rotor  20  laminations of  FIG. 4 . The rotor shaft  40  is typically made with a non-magnetic material. 
         [0034]      FIG. 1  and  FIG. 2  are provided to illustrate one of the principle construction requirements, which involves the direct-axis and quadrature-axis orientations and fixation of the rotor shaft  40 , relative to the stator  30  and rotor  20  lamination sets, in assembling the polyphase machine illustrated for the operational example. The perspectives illustrated in  FIG. 1  and  FIG. 2  display details that enable visualization of the effect that, as the rotor turns, when one stator  30  and rotor  20  lamination set is in a direct-axis orientation, the other stator  30  and rotor  20  set would be in a quadrature-axis orientation  FIG. 1  and  FIG. 2  are also illustrating a few construction methods that can be used to achieve the direct-axis and quadrature-axis relationships in the polyphase machine by using (1) the rotor  20  lamination sets with fixed references  37 A and  37 B, as shown in  FIG. 1 , and shifting the stator  30  lamination set by one pole width  33 , or by (2) using the stator  30  lamination sets with fixed references  38 A and  38 B, as illustrated in  FIG. 2 , and shifting the rotor  20  lamination set by one pole width  33 . 
         [0035]    As illustrated in  FIG. 5 , the field windings  50 , herein referred to as field-winding, field windings, field winding coils, or field excitation windings, are typically mounted on the field poles, or field magnetic poles  51 , that are located on the stator  30  embodiments to provide for the magnetic field or field excitation pole polarities of magnetic north (N)  52  and magnetic south (S)  53 . Also, illustrated in  FIG. 5  are armature windings  61  mounted on the armature poles, or armature magnetic poles  60 , as described in the previous art by Smith. The armature windings are typically mounted as a single unit or grouping around both the two adjacent armature poles, with the alternative being to wind each armature pole individually and then connect the two armature windings in series. 
         [0036]    Now to complete the disclosure of the inventive combination that significantly enhances the synergy of the assembled embodiments, consisting of two sets  10  and  11  of stator  30  and rotor  20  laminated embodiments of  FIG. 3  and  FIG. 4 , fixed in a unique relative angular relationship of direct-axis and quadrature-axis orientation, the connection scheme of the field excitation windings  50  will be disclosed, herein. 
         [0037]    A significant enhancement in the synergy is to be gained by using a special and basically unique connection scheme of the field windings  50 , in combination with the geometrically unique structure of the combined sets,  10  and  11 , of stator  30  and rotor  20  lamination embodiments, as described in the present disclosure. 
         [0038]    Therefore, as illustrated in  FIG. 6A  and  FIG. 6B , there is a group of stator  30  and rotor  20  laminated embodiments, consisting of two lamination sets  10  and  11  of stator  30  and rotor  20  embodiments. The stator  30  and rotor  20  lamination set  10  is illustrated in  FIG. 6A  with four field excitation windings  50 ; having numeric labeling of their terminals as  70  and  71 ,  72  and  73 ,  74  and  75 ,  76  and  77  on the direct-axis lamination set  10 , so that reference can be made to voltages and back-EMF&#39;s associated with each of the field windings  50 . For the operational example, herein described, all of the field windings  50  are wound identically and placed on the stator field poles  51  in the same orientation and having the winding direction in order to manage the polarities of their back-EMF and the polarity of the field winding  50  coils as they are connected together. The polarities of the magnetic poles  52  and  53 , as illustrated in  FIG. 5 , and the polarities of the field winding coils  50  are governed by the common “cross-dot” and “right-hand rule” conventions. The stator  30  and rotor  20  lamination set  11  is illustrated in  FIG. 6B  with four field excitation windings  50 ; having numeric labeling of their terminals as  80  and  81 ,  82  and  83 ,  84  and  85 ,  86  and  87  on the quadrature-axis lamination set  11 . Also, the characteristic plots of the field winding terminal voltages (or back-EMF&#39;s) versus rotational radians of the rotor are illustrated in  FIG. 10 ,  FIG. 11 , and  FIG. 12  to better convey an understanding of the working machine and the field winding  50  connection schemes and characteristics, using the above terminal labels  70 ,  71 ,  72 ,  73 , etc. 
         [0039]    Accordingly, with reference to  FIG. 6A , the field winding  50  with its terminals labeled  70  and  71 , on the direct-axis lamination set  10 , is shown to have a representative back-EMF of V 70-71 , and the field winding  50  with its terminals labeled  72  and  73  having a representative back-EMF of V 72-73 . Also, on the direct-axis lamination set  10 , is the field winding  50  with its terminals labeled  74  and  75  and having a representative back-EMF of V 74-75 , and a field winding  50  with its terminals labeled  76  and  77  and having a representative back-EMF of V 76-77 . 
         [0040]    Similarly, in  FIG. 6B  the field winding  50  with its terminals labeled  80  and  81 , on the quadrature-axis lamination set  11 , is illustrated to have a representative back-EMF of V 80-81 , and the field winding  50  with its terminals labeled  82  and  83  is shown to have a representative back-EMF of V 82-83 . Also, illustrated on the quadrature-axis lamination set  11 , is a field excitation winding  50  with its terminal labels  84  and  85  and having a representative back-EMF of V 84-85 , and another field winding  50  with its terminals labeled  86  and  87  and having a representative back-EMF of V 86-87 . Further more, for example purposes, the standard nomenclature used herein is intended to be that the voltage V 70-71  represents the voltage at terminal  70  with respect to terminal  71 , and likewise, the voltage V 71-70  represents the voltage at terminal  71  with respect to terminal  70 . 
         [0041]    As the assembly of the machine progresses, the field windings  50  are connected using the scheme in  FIG. 7 . The primary principle in all the connection schemes for the field winding coils  50  is to effect an overall objective of using the back-EMF of each of the field windings  50  to achieve a back-EMF cancellation scheme, which substantially negates or minimizes the aggregate back-EMF being generated by the field winding coils  50 . In addition,  FIG. 9  displays one of the preferred connection schemes for the field windings  50 , as well as the back-EMF voltages with example vector polarities  79  illustrated for some of the field winding coils  50 . This is the effect that is being illustrated in  FIG. 12A ,  FIG. 12B  and  FIG. 12C , and specifically the aggregate back-EMF V 70-82 , which is illustrated by the graphical plot in  FIG. 12C . The aggregate sum (or, aggregate vectorial sum) of the back-EMF&#39;s comprising V 70-82  has an effect on the field winding, excitation voltage source (FWEV)  90 , consistent with an opposing voltage source in the field excitation circuit  91 , and as one that would present an undesirable harmonic voltage, as illustrated in  FIG. 12A  and  FIG. 12B , in the context of an opposing, relatively high back-EMF source.  FIG. 8  is shown to illustrate the preferred scheme of connecting the field excitation windings in the previous art. The connection scheme in  FIG. 8  would result in a relatively high harmonic-producing back-EMF voltage source in the field winding excitation circuit  91 .