Abstract:
A generator includes a stator that has permanent magnets that complete a magnetic circuit across a series of gaps and through a generator coil. The rotor also includes permanent magnets that complete a magnetic circuit across a gap and through a rotor coil. When the rotor poles align with the stator poles, the stator and rotor magnetic circuits are broken, and new magnetic circuits are completed between the stator and rotor permanent magnets that cross the gap between the stator and rotor poles. A rotor coil can be used to boost the attraction/repulsion between the rotor and stator magnets. Alternating between these magnetic circuits as the prime mover rotates the rotor generates electricity.

Description:
FIELD OF THE INVENTION 
     The field of the invention is electromagnetic generators that increase efficiency using rotor field coils and rotor magnets to switch between alternate magnetic circuits. 
     BACKGROUND 
     The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. 
     Alternating current generators in which the stators utilize permanent magnets to provide the magnetic flux to armature coils suffer numerous disadvantages. Maintaining terminal voltage when an external load is connected to the generator, or when the external load varies, can be technologically challenging. Additionally, much of the magnetic flux from the permanent magnets is unused during operation of traditional generators that utilize magnets. 
     To address these problems, U.S. Pat. No. 2,816,240 to Zimmerman discloses a generator that includes field coils to maintain terminal voltage. Zimmerman&#39;s stator comprises two sets of circular laminations, one of which has two permanent magnets inserted into two angular segments removed from each lamination and oriented such that the like poles face each other. A flux-reversing multi-pole rotor acts as a flux reversing switch for the flux passing though the armature windings when successive teeth of the rotor are in alignment with the successive poles of the stator. When an external load is connected to the generator, excitation of the field coils maintains terminal voltage. However, Zimmerman fails to efficiently use magnetic flux from the stator permanent magnets, because Zimmerman&#39;s flux paths travel both through the rotor and around the stator circumference. 
     In U. S. Patent Application No. 2008/0272664, Flynn discloses electromechanical devices that have increased power density and efficiency. Flynn&#39;s electromechanical devices have stators comprised of alternating stator segments and permanent magnets. When Flynn&#39;s rotor shaft is rotated by external prime mover, Flynn&#39;s bridge and pole wound electro-mechanical device functions as a generator with stator segments having reluctance bridges with an air gap and a reluctance gap control coil. However, Flynn&#39;s electromechanical devices only decrease cogging torque without providing any motive force. 
     Thus, there is still a need for generators that utilize alternate magnetic paths to produce torque through the rotor and produce electricity through the stator in an energy-efficient manner. 
     All publications identified herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. 
     SUMMARY OF THE INVENTION 
     The inventive subject matter provides a generator that produces electricity using gaps in the stator and gaps between the stator and rotor poles to alternate between magnetic circuits. One magnetic circuit connects stator magnet pairs and travels through the stator, which includes gaps on either end of a generator coil wrapped around a generator core. An alternate magnetic circuit connects stator and rotor magnets and crosses the gap between the rotor and stator poles as the poles substantially align during operation of the generator. 
     Stators according to the inventive subject matter include first and second magnetic flux elements having first and second stator poles, respectively. A first magnetic flux donor, e.g., a permanent magnet, donates magnetic flux having a first polarity to the first magnetic flux element. A second magnetic flux donor, e.g., a permanent magnet, donates magnetic flux of having a second polarity, opposite to the first polarity, to the second magnetic flux element. The first magnetic flux element is magnetically coupled to the first end of the generator core across a first gap, and the second magnetic flux element is magnetically coupled to the second end of the generator core across a second gap. Optionally, the stator can include a magnetic flux yoke, magnetically coupled to the first and second ends of the generator core. 
     In an exemplary embodiment, a rotor comprises a third magnetic flux element having first and second rotor poles. A rotor coil wraps around the third magnetic flux element. The third magnetic flux element also includes a third gap that is at least partially disposed within the rotor coil. Third and fourth magnetic flux donors donate magnetic flux having the second and first polarities, respectively, to the third magnetic flux element on opposite sides of the third gap and rotor coil. The third magnetic flux donor donates magnetic flux having the second polarity to the third magnetic flux element proximate to the first rotor pole, and the fourth magnetic flux donor donates magnetic flux having the first polarity to the third magnetic flux element proximate to the second rotor pole. 
     As the rotor rotates, alignment of the first rotor pole with the first stator pole creates a fourth gap having a reluctance that is less than the reluctance of the first gap. Because alignment of the first rotor pole with the first stator pole creates a lower reluctance path, magnetic flux from the first magnetic flux donor completes a magnetic circuit with magnetic flux from the third magnetic flux donor across the fourth gap. Passing current through the rotor coil as the first rotor and stator poles align augments the torque by adding magnetic flux to the magnetic flux from the third magnetic flux donor. 
     The magnetic circuit between the first and third magnetic flux donors breaks as the first rotor pole rotates away from the first stator pole. Magnetic flux from the first magnetic flux donor passes through the first magnetic flux element, across the first gap, through the generator core and generator coil, across the second gap and through the second magnetic flux element to complete a magnetic circuit with the second magnetic flux donor. Thus, as the rotor rotates, magnetic flux through the generator coil varies, generating alternating current. 
     The stator may further include a magnetic flux yoke that magnetically couples to the first and second ends of the generator core. 
     In another embodiment, the third and fourth magnetic flux donors comprise a permanent magnet disposed within the third gap. The rotor coil directs magnetic flux of the first polarity toward the first rotor pole and magnetic flux of the second polarity to the second rotor pole. 
     It should be appreciated that the stator and rotor can each comprise an odd number of pole pairs. 
     Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1A  is a cross sectional view of a stator. 
         FIG. 1B  is a cross sectional view of a rotor. 
         FIG. 1C  shows a generator viewed down the rotational axis. 
         FIG. 1D  shows the magnetic circuit formed when the stator and rotor poles are substantially aligned. 
         FIG. 2A  is a cross sectional view of a generator that has another embodiment of a rotor and shows a first magnetic circuit. 
         FIG. 2B  shows the generator of  FIG. 2A  and a second magnetic circuit. 
     
    
    
     DETAILED DESCRIPTION 
     The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed. 
     The generators described herein efficiently generate alternating current using alternate magnetic circuits.  FIG. 1A  shows an exemplary embodiment of stator  100 . Stator  100  includes first magnetic flux elements  110  and  120 , which have first and second stator poles  111  and  122 , respectively. Magnetic flux donors  101  and  102  magnetically couple to magnetic flux elements  110  and  120 , respectively. First magnetic flux element  110  magnetically couples to first end  141  of generator core  140  across gap  10 , and second magnetic flux element  120  magnetically couples to second end  142  of generator core  140  across gap  20 . Generator coil  145  wraps around generator core  140 . As shown in  FIG. 1A , magnetic flux donor  101  completes a stator magnetic circuit with magnetic flux donor  102 . The stator magnetic circuit travels through first magnetic flux element  110 , across gap  10 , through generator core  140  and generator coil  145 , across gap  20 , and through magnetic flux element  120 . The stator can optionally include magnetic flux yoke  160 . 
       FIG. 1B  shows rotor  150 . Rotor  150  includes third magnetic flux element  130 , which has gap  30  at least partially disposed within rotor coil  135 . Third magnetic flux element  130  has first and second rotor poles  131  and  132 , respectively. Third magnetic flux donor  103  and fourth magnetic flux donor  104  magnetically couple to third magnetic flux element  130 . Magnetic flux from third magnetic flux donor  103  and fourth magnetic flux donor  104  completes a rotor magnetic circuit through third magnetic flux element  130  and across gap  30 . 
       FIG. 1C  shows a generator viewed down the rotational axis. Stator  100  has six pairs of stator poles. Rotor  150  has four pairs of rotor poles. As rotor  150  turns, first rotor pole  131  substantially aligns with first stator pole  111 , as shown along axis  170  of  FIG. 1C  and in  FIG. 1D . As used herein, the term “substantially aligned” means that gap  40  between first rotor pole  131  and first stator pole  111  has a lower reluctance than gaps  10 ,  20 , and  30 , so the stator and rotor magnetic circuits are broken. Thus, when first rotor pole  131  and first stator pole  111  are substantially aligned, magnetic flux donors  101  and  103  complete an alternate magnetic circuit that passes through stator pole  111 , gap  40 , and rotor pole  131 . Similarly, magnetic flux donor  102  completes an alternate magnetic circuit with magnetic flux donor  104 . The magnetic flux through these circuits can be augmented by applying current through rotor coil  135 . It should be appreciated that the on and off timing of current through rotor coil  135  is configured to boost rotor momentum. 
     As the rotor continues to rotate, the reluctance across gap  40  between the rotor and stator poles increases and the alternate magnetic circuit is broken, and the stator and rotor magnetic circuits are reformed. Along axis  180  ( FIG. 1C ), the rotor poles are approximately midway between the two nearest stator poles. 
     Another exemplary embodiment of a rotor according to the inventive subject matter is illustrated in  FIG. 2A . Rotor  250  comprises third magnetic flux element  230  having gap  30 . Third magnetic flux donor  203  and fourth magnetic flux donor  204  are disposed within gap  30 . Rotor coil  235  wraps around magnetic flux element  230 , and gap  30  extends at least partially into rotor coil  235  toward both rotor poles  231  and  232 . 
     Stator  200  includes first magnetic flux elements  210  and  220 , which have first and second stator poles  211  and  222 , respectively. Magnetic flux donors  201  and  202  magnetically couple to magnetic flux elements  210  and  220 , respectively. 
       FIG. 2A  also shows the magnetic circuit formed when rotor poles  231  and  232  are substantially aligned with stator poles  211  and  222 , respectively. As first rotor pole  231  rotates toward first stator pole  211 , current is applied to rotor coil  235 , directing magnetic flux from third magnetic flux donor  203  to complete a magnetic circuit across gap  40  with magnetic flux from first magnetic flux donor  201 . The magnetic flux from rotor coil  235  also directs magnetic flux from forth magnetic flux donor  204  to complete a magnetic circuit with second magnetic flux donor  202  across gap  50 . Magnetic flux from rotor coil  235  boosts the attractive force between the rotor and stator poles. 
     As rotor  250  continues rotating, rotor poles  231  and  232  rotate out of substantial alignment with stator poles  211  and  222 , respectively, and current through rotor coil  235  is reversed. Reversing the current through rotor coil  235  reverses the direction of the magnetic flux from magnetic flux donors  203  and  204  as shown in  FIG. 2B , and the stator poles repel the rotor poles, boosting rotor momentum. First magnetic flux element  210  magnetically couples to first end  241  of generator core  240  across gap  10 , and second magnetic flux element  220  magnetically couples to second end  242  of generator core  240  across gap  20 . Generator coil  245  wraps around generator core  240 . The stator may optionally include magnetic flux yoke  260  that magnetically couples to first and second ends ( 241  and  242 ) of the generator core. 
     One should appreciate that the disclosed techniques provide many advantageous technical effects including efficiently using permanent magnets to generate electricity by providing an alternate magnetic circuit through the rotor. 
     As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. 
     Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. 
     As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously. 
     It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.