Patent Publication Number: US-2023145116-A1

Title: Rotating electrical machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. JP 2021-183712, filed on Nov. 10, 2021, the contents of which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a rotating electrical machine and relates more specifically to a three-phase rotating electrical machine utilizing a delta connection as the connection system. 
     BACKGROUND 
     A three-phase rotating electrical machine of the related art includes a stator and a corresponding rotor having permanent magnets alternately arranged along the circumference for different SN magnetism; and a three-phase coil is wound around a plurality of iron cores arranged along the circumference on the stator. 
     [Citation List] 
     [Patent Literature] 
     Patent Literature 1: JP H2-254950 A 
     The wire connection system for three-phase coils includes two connection systems such as a star connection and a delta connection, and consideration is given to a stator coil wiring utilizing the delta connection system. 
     In the delta connection stator utilized in the three-phase rotating electrical machine of the related art, as shown in  FIG.  6   , the three-phase coil is wound on iron cores arrayed along the circumference in the sequence shown in  FIG.  7   . The plurality of coils is respectively serially connected by the crossover wires for each phase of coils A, B, and C. First, the U-phase coil A is wound in the sequence A1-A2-A3-A4-A5-A6; next, the V phase coil B is wound in the sequence B1-B2-B3-B4-B5-B6; and the W phase coil C is wound in the sequence C1-C2-C3-C4-C5-C6. In the sequence shown in  FIG.  7   , all of the phase coils are wound in the same direction. In the coil termination process in this case, A1, C6 are connected at a contact point X; A6, B1 are connected at a contact point Y; and B6, C1 are connected at a contact point Z. 
     However, when all coils are wound in the same direction, the contact point X is arranged in proximity to A1, C6 while the contact point Y is arranged physically separate from A6, B1 and the contact point Z is arranged physically separate from B6, C1. Assembly is therefore difficult and the insulation is also difficult to maintain. The separated contact points for example must be treated with adhesive impregnation due to unstable floating of wiring and wiring mistakes are prone to occur. 
       FIG.  8 A  is a drawing showing an outer view of the delta connection stator of the related art on which coils are wound.  FIG.  8 B  is an enlarged outer view of one surface. In the delta connection stator of the related art as shown in  FIGS.  8 A and  8 B , the crossover wires connecting each coil are drawn along the same surface. The crossover wires arranged on the same surface overlap each other, and the location with the three crossover wires placed densely together increases the thickness. Such increase in the thickness does not satisfy the demands in recent years for device downsizing. For example, when there are limits on the thickness of the stator in  FIGS.  8 A and  8 B  due to the device structure, wiring must be performed during manufacturing with great caution at the location with the crossover wires placed densely together and the wiring is therefore not easy to perform. 
     Unlike the wiring system of the related art, Patent Literature 1 proposes winding just one of the three-phase coils in the reverse winding direction. However, in the method described in Patent Literature 1, the coil is still wound along the same surface and therefore there are the following problems. 
     The structure of the crossover wire of the delta connection stator of the related art is shown in  FIG.  9 A , and the structure of the crossover wire of Patent Literature 1 is shown in  FIG.  9 B . In the structure of the related art, the winding direction for all phases is the same as shown in  FIG.  9 A  so the crossover wires are wired in the same way on all the iron cores. However, in the structure in Patent Literature 1 as shown in  FIG.  9 B , a coil of just one of the three-phase coils is wound in the reverse winding direction so that the crossover wire of the reversely wound coil is arranged at a slant state. 
     First, in the structure of Patent Literature 1, the slanted crossover wire interferes with winding coils on adjacent iron cores. The winding must be performed for each phase, however in the structure of Patent Literature 1, the phase for the second winding is performed in the reverse direction so that the slanted crossover wire interferes with the winding for the coil of the phase for the last winding. 
     Further, in the structure of Patent Literature 1 as shown in  FIG.  9 B , there is a location where crossover wires of another phase are in contact with the slanted crossover wire. Since the slanted crossover wire is pulled to the opposite surface while contacting the crossover wires of another phase, the tension applied to the contact location causes rubbing to occur so that damages possibly occurs on the enamel coating of the copper wire. When the coating of the copper wire is damaged, the insulation might be impossible to maintain. Electrical shorts might occur in that case at the contact locations. 
     In view of the aforementioned problems, the present invention therefore has the object of providing a rotating electrical machine that maintains a high degree of insulation for the copper wire and facilitates the wiring during manufacturing. 
     SUMMARY 
     To resolve the aforementioned problems, the rotating electrical machine of the present invention includes a stator having a plurality of iron cores arranged along the circumference and windings wound on each of the plurality of iron cores, and a rotor having permanent magnets arranged to have different magnetism along the circumference, in which the windings include a first phase winding, a second phase winding, and a third phase winding connected in a delta connection, each phase winding connected in series with a crossover wire, the winding direction of the first phase winding and the third phase winding is the first winding direction, the winding direction of the second phase winding is the second winding direction which is reverse to the first winding direction, and the crossover wire connecting the first phase winding and the crossover wire connecting the third phase winding are arranged on the first side of the stator, and the crossover wire connecting the second phase winding is arranged on the second surface opposite the first side. 
     According to this aspect, a rotating electrical machine for maintaining a high degree of insulation for the copper wire and facilitating the wiring during manufacture is able to be provided. 
     In the rotating electrical machine described in [1] above, a first terminal of the serially connected first phase winding and a second terminal of the serially connected third phase winding may be connected; and a second terminal of the serially connected second phase winding and a second terminal of the serially connected first phase winding may be connected; and a first terminal of the serially connected third phase winding and a first terminal of the serially connected second phase winding may be connected. 
     According to this aspect, the rotating electrical machine is able to be handled as the rotating electrical machine that is electrically the same as that of the related art even in the reverse winding direction. 
     In the rotating electrical machine described in [2], the first side may include a connection area for contact points where the two terminals for the first phase winding, the two terminals for the second phase winding, and the two terminals for the third phase winding are connected respectively, and a lead wire connecting to an external section. 
     According to this aspect, the number of conducting wires that are utilized to span adjacent iron cores and reach connection points is able to be reduced. 
     In the rotating electrical machine described from [1] to [3] above, the rotating electrical machine may be configured as a generator to generate electromotive force in the windings by rotation of the rotor. 
     According to this aspect, a generator for maintaining a high degree of insulation for the copper wire and facilitating the wiring during manufacture is able to be provided. 
     To resolve the aforementioned problems, the stator of the present invention has a plurality of iron cores arranged along the circumference and windings wound on each of the plurality of iron cores, in which the windings include a first phase winding, a second phase winding, and a third phase winding connected in a delta connection, each phase winding connected in series with a crossover wire, the winding direction of the first phase winding and the second phase winding is the first winding direction, the winding direction of the third phase winding is the second winding direction which is reverse to the first winding direction, and the crossover wire connecting the first phase winding and the crossover wire connecting the second phase winding are arranged on the first side of the stator, and the crossover wire connecting the third phase winding is arranged on the second surface opposite the first side. 
     According to this aspect, a stator utilized in a rotating electrical machine that maintains a high degree of insulation for the copper wire and facilitates the wiring during manufacture is able to be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  shows a front side view of the overall structure of the generator of the present embodiment. 
         FIG.  1 B  shows a cross-sectional view of the generator in  FIG.  1 A . 
         FIG.  2    shows the stator prior to winding the coil. 
         FIG.  3    shows the structure of the coil to be wound on the stator. 
         FIG.  4    shows an arrangement example of the crossover wire of the coil of the stator of the present embodiment. 
         FIGS.  5 A through  5 C  show the winding structure on the stator for the generator of the present embodiment. 
         FIG.  5 A  shows an external view of the stator on which the coil is wound. 
         FIG.  5 B  shows an enlarged fragmentary external view of the A side of the stator. 
         FIG.  5 C  shows an enlarged fragmentary external view of the B side of the stator. 
         FIG.  6    shows the stator prior to winding the coil on the stator of the related art. 
         FIG.  7    shows the structure of the coil to be wound on the stator of the related art. 
         FIGS.  8 A and  8 B  show the crossover wire for the coil of the stator utilized in the generator of the related art. 
         FIG.  8 A  shows an outer view of the delta connection stator of the related art on which coils are wound. 
         FIG.  8 B  shows an enlarged outer view of one surface of the stator in  FIG.  8 A . 
         FIGS.  9 A and  9 B  show the winding structure on the stator utilized in the generator of the related art. 
         FIG.  9 A  shows the structure of the crossover wire of the delta connection stator of the related art. 
         FIG.  9 B  shows the structure of the crossover wire of Patent Literature 1. 
     
    
    
     DETAILED DESCRIPTION 
     Specific examples of the embodiments of the present invention are described with reference to the drawings. In the following description, common structural elements of the embodiments are designated with identical reference numerals and redundant descriptions are omitted. In the following embodiments, a generator is utilized as an example of the rotating electrical machine. 
       FIGS.  1 A and  1 B  show drawings showing the overall structure of the generator of the present embodiments.  FIG.  1 A  is a drawing showing the generator as seen from the front side, and  FIG.  1 B  is a drawing showing a cross-section of the generator in  FIG.  1 A . 
     A generator  1  as shown in  FIGS.  1 A and  1 B  has a structure including a rotor  10  and a stator  20  arranged coaxially. The generator  1  of the present embodiment is an outer rotor type generator in which the rotor  10  is configured to enclose the stator  20  at the edge of the rotor  10 . 
     The rotor  10  includes a rotor body  11 , a magnet  12 , and a magnet case  13 . The rotor body  11  is configured to allow rotation of the rotor  10  centering on a rotation axis R for insertion of a rotary member such as a crankshaft. In other words, when the crankshaft rotates, the rotor  10  is inter-connected to also rotate centering on the rotation axis R A cooling hole h 1  is also formed on the rotor body  11 . 
     The magnet  12  is arranged circumferentially along the edge of the rotor body  11  in a state held within a magnet case  13 . The magnet  12  is a permanent magnet arranged to have different magnetism along the circumference. The magnet  12  is installed for example along the circumference prior to magnetization and then magnetized such that the N poles and S poles are alternately arrayed at fixed intervals. 
     The stator  20  includes a stator body  21 , an iron core  22 , and a coil (winding)  23 . The coil  23  can be configured from a conductive member covered by an insulation coating on the periphery. The iron core  22  is formed to protrude at the outer circumference of the stator body  21  and the coil  23  is wound on the iron core  22 . The stator body  21  has a hole h 2  for insertion of a fixation screw, etc., to fix the generator  1 . 
     The generator  1  is configured from the magnet  12  of the rotor  10 , and the coils  23  of the stator  20  wound on the iron core  22 , facing each other. In the generator  1  configuration, the rotation of the rotor  10  centering on the rotation axis R due to a rotary member such as a crankshaft results in rotation of the magnet  12  alternately magnetized at the N and S poles along the circumference. The rotation of the rotor  10  results in a change in the magnetic field formed between the magnet  12  and the iron core  22  of the stator  20 ; and an electromotive force is generated in the coil  23  wound on the iron core  22  due to the electromagnetic induction effect so that electricity is generated by the flow of induced current. 
     In the generator of the present embodiment, the structure of the coil wound on the stator renders the effect that a high degree of insulation is maintained for the copper wire and facilitates the wiring during manufacture. The structure of the coil wound on the stator is described further. 
     The stator  20  utilized in the generator of the present embodiment has iron cores  22  with the three-phase coil  23  wound in a delta connection. In the present embodiment, a description is given utilizing a three-phase 18 pole stator as an example, however there is no particular limit on the number of poles. 
       FIG.  2    is a drawing showing the stator prior to winding the coil of the present embodiment.  FIG.  3    is a drawing showing the structure of the coil wound on the stator of the present embodiment. 
       FIG.  2    shows the 18 pole iron cores  22 _ 1 ,  22 _ 2 ,  22 _ 3 ,  22 _ 4 ,  22 _ 5 ,  22 _ 6 ,  22 _ 7 ,  22 _ 8 ,  22 _ 9 ,  22 _ 10 ,  22 _ 11 ,  22 _ 12 ,  22 _ 13 ,  22 _ 14 ,  22 _ 15 ,  22 _ 16 ,  22 _ 17 ,  22 _ 18 . The iron cores  22 _ 1  through  22 _ 18  may be referred to simply as “iron core  22 ” if not identifying them individually. 
       FIG.  3    shows the coils  23 _ 1  (U 1 ),  23 _ 2  (U 2 ),  23 _ 3  (U 3 ),  23 _ 4  (U 4 ),  23 _ 5  (U 5 ),  23 _ 6  (U 6 ) serially connected by a crossover wire  24   a , the coils  23 _ 7  (V 1 ),  23 _ 8  (V 2 ),  23 _ 9  (V 3 ),  23 _ 10  (V 4 ),  23 _ 11  (V 5 ),  23 _ 12  (V 6 ) serially connected by a crossover wire  24   b , and the coils  23 _ 13  (W 1 ),  23 _ 14  (W 2 ),  23 _ 15  (W 3 ),  23 _ 16  (W 4 ),  23 _ 17  (W 5 ),  23 _ 18  (W 6 ) serially connected by a crossover wire  24   c . The coils  23 _ 1  through  23 _ 18  may be referred to simply as “coil  23 ” if not identifying them individually. The crossover wires  24   a ,  24   b , and  24   c  may in the same way be referred to simply as “crossover wire  24 ” if not identifying them individually. 
     In the coil structure shown in  FIG.  3   , the coils  23 _ 1  (U 1 ),  23 _ 2  (U 2 ),  23 _ 3  (U 3 ),  23 _ 4  (U 4 ),  23 _ 5  (U 5 ),  23 _ 6  (U 6 ) are the coils  23 U wound in the U phase (first phase); the coils  23 _ 7  (V 1 ),  23 _ 8  (V 2 ),  23 _ 9  (V 3 ),  23 _ 10  (V 4 ),  23 _ 11  (V 5 ),  23 _ 12  (V 6 ) are the coils  23 V wound in the V phase (second phase); and the coils  23 _ 13  (W 1 ),  23 _ 14  (W 2 ),  23 _ 15  (W 3 ),  23 _ 16  (W 4 ),  23 _ 17  (W 5 ),  23 _ 18  (W 6 ) are the coils  23 W wound in the W phase (third phase). Here, U 1  through U 6 , V 1  through V 6 , W through W 6  for  23 U,  23 V,  23 W are utilized for purposes of convenience to identify each phase. 
     In the structures shown in  FIG.  2    and  FIG.  3 ,  18    coils  23 _ 1  (U 1 ),  23 _ 2  (U 2 ),  23 _ 3  (U 3 ),  23 _ 4  (U 4 ),  23 _ 5  (U 5 ),  23 _ 6  (U 6 ),  23 _ 7  (V 1 ),  23 _ 8  (V 2 ),  23 _ 9  (V 3 ),  23 _ 10  (V 4 ),  23 _ 11  (V 5 ),  23 _ 12  (V 6 ), coil  23 _ 13  (W 1 ),  23 _ 14  (W 2 ),  23 _ 15  (W 3 ),  23 _ 16  (W 4 ),  23 _ 17  (W 5 ),  23 _ 18  (W 6 ) can be respectively wound on the corresponding positions relative to the 18 pole iron cores  22 _ 1  (U 1 ),  22 _ 2  (V 1 ),  22 _ 3  (W 1 ),  22 _ 4  (U 2 ),  22 _ 5  (V 2 ),  22 _ 6  (W 2 ),  22 _ 7  (U 3 ),  22 _ 8  (V 3 ),  22 _ 9  (W 3 ),  22 _ 10  (U 4 ),  22 _ 11  (V 4 ),  22 _ 12  (W 4 ),  22 _ 13  (U 5 ),  22 _ 14  (V 5 ),  22 _ 15  (W 5 ),  22 _ 16  (U 6 ),  22 _ 17  (V 6 ),  22 _ 18  (W 6 ). 
     In other words, in regard to the U-phase, the coil  23 _ 1  (U 1 ) is wound on the iron core  22 _ 1  (U 1 ), and the coil  23 _ 2  (U 2 ) is wound on the iron core  22 _ 4  (U 2 ), and the coil  23 _ 3  (U 3 ) is wound on the iron core  22 _ 7  (U 3 ), and the coil  23 _ 4  (U 4 ) is wound on the iron core  22 _ 10  (U 4 ), and the coil  23 _ 5  (U 5 ) is wound on the iron core  22 _ 13  (U 5 ), and the coil  23 _ 6  (U 6 ) is wound on the iron core  22 _ 16  (U 6 ). 
     In regard to the V-phase, the coil  23 _ 7  (V 1 ) is wound on the iron core  22 _ 2  (V 1 ), and the coil  23 _ 8  (V 2 ) is wound on the iron core  22 _ 5  (V 2 ), and the coil  23 _ 9  (V 3 ) is wound on the iron core  22 _ 8  (V 3 ), and the coil  23 _ 10  (V 4 ) is wound on the iron core  22 _ 11  (V 4 ), and the coil  23 _ 11  (V 5 ) is wound on the iron core  22 _ 14  (V 5 ), and the coil  23 _ 12  (V 6 ) is wound on the iron core  22 _ 17  (V 6 ). 
     In regard to the W-phase, the coil  23 _ 13  (W 1 ) is wound on the iron core  22 _ 3  (W 1 ), and the coil  23 _ 14  (W 2 ) is wound on the iron core  22 _ 6  (W 2 ), and the coil  23 _ 15  (W 3 ) is wound on the iron core  22 _ 9  (W 3 ), and the coil  23 _ 16  (W 4 ) is wound on the iron core  22 _ 12  (W 4 ), and the coil  23 _ 17  (W 5 ) is wound on the iron core  22 _ 15  (W 5 ), and the coil  23 _ 18  (W 6 ) is wound on the iron core  22 _ 18  (W 6 ). 
     The position to wind the U-phase, V-phase, W-phase coils  23  on the iron cores  22  is in this way different only for the V-phase that is the middle phase. According to this configuration, the electrical characteristics of the terminals of the coil  23 U,  23 V,  23 W for the U-phase, V-phase, and W-phase are the same as the stator  20  of the related art shown in  FIGS.  6 ,  7    even if only the V-phase coil that is in the middle is wound in the reverse winding direction. 
     In the coil configuration shown in  FIG.  3   , the U-phase (first phase)  23 U and the W-phase (third phase) coil  23 W are wound in the same winding direction, and only the V-phase (second phase) coil  23 V is wound in the reverse winding direction. The three-phase coils  23 U,  23 V,  23 W are connected in a delta connection. In other words, the terminal U 1  (first terminal) for the coil  23 U wound in the U-phase (first phase) and the terminal W 6  (second terminal) for the coil  23 W wound in the W-phase (third phase) are connected at the contact point X; the terminal V 6  (second terminal) for the coil  23 V wound in the V phase (second phase) and the terminal U 6  (second terminal) for the coil  23 U wound in the U-phase (first phase) are connected at the contact point Y; and the terminal W 1  (first terminal) for the coil  23 W wound in the W-phase and the terminal V 1  (first terminal) for the coil  23 V wound in the V-phase are connected at the contact point Z. 
     On the stator  20  of the present embodiment, only the V-phase coil  23 V that is in the middle among the three phases is wound in the reverse winding direction so that the V-phase coil  23 V is arranged in the direction reverse to the contact point. In other words, the U-phase coil  23 U and the V-phase coil  23 V are connected to the terminal (second terminal) for the coil  23 _ 6  (U 6 ) and the terminal (second terminal) for the coil  23 _ 12  (V 6 ). The V-phase coil  23 V and the W-phase coil  23 W are connected to the terminal (first terminal) for the coil  23 _ 7  (V 1 ) and the terminal (first terminal) for the coil  23 _ 13  (W 1 ). The W-phase coil  23 W and the U-phase coil  23 U are connected to the terminal (second terminal) of the coil  23 _ 18  (W 6 ) and the terminal (first terminal) of the coil  231  (U 1 ). 
     By winding only the V-phase coil  23 V in the reverse winding direction in this way, the terminals for the coils wound on adjacent iron cores are connected at each of the contact points, X, Y, and Z. In other words, the terminals for the coils wound on the adjacent iron cores W 6  and U 1  are connected at the contact point X; the terminals for the coils wound on the adjacent iron cores U 6  and V 6  are connected at the contact point Y; and the terminals for the coils wound on the adjacent iron cores V 1  and W 1  are connected at the contact point Z. According to this structure, the terminals of the coils to be connected are placed in close physical proximity, which leads easy assembly and is advantageous for maintaining insulation. 
     On the stator  20  of the present embodiment, the crossover wires  24   a ,  24   c  for the U-phase and W-phase coils  23 U,  23 W are arranged on the same surface, and only the crossover wire  24   b  for the V-phase coil  23 V is arranged on an opposite surface. 
       FIG.  4    is a drawing showing an arrangement example of the crossover wire for the coil of the stator of the present embodiment. 
       FIG.  4    shows the crossover wire  24   a  for the U-phase coils  23 _ 1  (U 1 ),  23 _ 2  (U 2 ); the crossover wire  24   b  for the V-phase coils  23 _ 7  (V 1 ),  23 _ 8  (V 2 ); and the crossover wire  24   c  for the W-phase coils  23 _ 13  (W 1 ),  23 _ 14  (W 2 ). On the stator  20  of the present embodiment as shown in  FIG.  4   , the crossover wire  24   a  for the U-phase coil  23 U and the crossover wire  24   c  for the W-phase coil  23 W are arranged on the A side, and only the crossover wire  24   b  for the V-phase coil  23 V is arranged on the B side positioned opposite the A side. Employing this structure ensures that no slanted crossover wire is formed, even if only the V-phase coil  23 V is wound in the reverse winding direction to the other phase coils  23 U,  23 W. The crossover wire  24  in this way tends not to interfere with the winding of the other phase coils  23 , and damage on the insulation coating is difficult to occur at the contact location with the crossover wire  24  for the other phase coils  23 . 
     Furthermore, in the generator of the present embodiment, the three-phase coils  23  connected beforehand as a single coil at the contact points X, Y, Z may be wound on the iron core  22  rather than winding the coils  23  on the iron core  22  and connecting them at the contact points X, Y, Z after preparing the three-phase coils  23  to be wound on the stator as three separate coils. 
     In this case, first of all, the U-phase coil  23 U can be wound in the sequence of U 1 -U 2 -U 3 -U 4 -U 5 -U 6 , next the V-phase coil  23 V can be wound in the sequence of V 6 -V 5 -V 4 -V 3 -V 2 -V 1 , and the W-phase coil  23 W can be wound in the sequence of W 1 -W 2 -W 3 -W 4 -W 5 -W 6 . Winding the coil  23  in this sequence allows easy winding. For winding, for example, a needle-type coil winder can be utilized. 
       FIGS.  5 A- 5 C  are drawings illustrating the winding structure on the stator for the generator of the present embodiment.  FIG.  5 A  is a drawing showing an external view of the stator on which the coil is wound;  FIG.  5 B  is a drawing showing an enlarged fragmentary external view of the A side; and  FIG.  5 C  is a drawing showing an enlarged fragmentary external view of the B side. 
     As shown in  FIGS.  5 A- 5 C , in the stator  20  for the generator of the present embodiment, the crossover wire  24   a  for the U-phase coil  23 U and the crossover wire  24   c  for the W-phase coil  23 W are arranged on the A side; and the crossover wire  24   b  for the V-phase coil  23 V is arranged on the B side. Therefore, even at a maximum there are two overlapping crossover wires  24 , there is no need to depress the wires when there are limitations on the thickness or impregnate the coil with adhesive in manufacturing processes, which makes the winding easy. 
     In the embodiment shown in  FIG.  5 A , the A side includes a connection area for the contact points X, Y, Z where the two terminals for the U-phase coil  23 U, the two terminals for the V-phase coils  23 V, and the two terminals for the W-phase coils  23 W are connected respectively; and for the lead wire connecting to an external section. Arranging the connection area for the contact points X, Y, Z and the lead wire connecting to an external section in this way on the A side where the two crossover wires  24   a ,  24   c  are arranged reduces the number of conducting wires that are utilized to span adjacent iron cores and reach connection points. However, this structure is not always required and the B side may include the connection area. 
     Extension of the Embodiment 
     Specific examples are described based on the embodiment of the invention as rendered by the inventors. However, it is understood that the present invention is not limited by these examples and modifications not departing from the scope of the invention are permissible. 
     In the above embodiments, a generator utilized as the rotating electrical machine is described as an example, however, the present invention is not limited to this example and other electrical rotating machines such as motors may also be utilized. If utilizing a motor as the electrical rotating machine, by applying an electrical current flow to the coil  23 , the iron cores  22  are magnetized by an electromagnetic induction effect, to rotate the rotor  10  by attracting and repelling the magnet  12 . 
     The description of the embodiments utilizes an example for the case where the first phase of winding is U-phase, the second phase of winding is V-phase, and the third phase of winding is the W-phase, however, the present invention is not limited to the above. The invention is further not limited to the sequence of first phase, second phase, third phase as the winding sequence.