Patent Publication Number: US-2011057534-A1

Title: Reverse electromotive force generating motor

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
     The present invention relates to a reverse electromotive force generating motor having both a function of an engine motor and a function of an electric generator. 
     When one of a three-phase alternate current changes a polarity and a voltage thereof, the voltage becomes zero at one point. A reverse electromotive force is generated when the voltage becomes zero. When the reverse electromotive force is supplied from, for example, a motor to an inverter due to a short-circuit fault of the inverter, a cable connecting the motor and the inverter may be damaged. 
     Patent Reference has disclosed a motor having a short circuit fault detecting circuit in order to prevent the problem described above.
     Patent Reference: Japanese Patent Publication No. 2007-181345   

     In the motor disclosed in Japanese Patent Application, the short circuit fault detecting circuit has to be provided in the motor. Consequently, a more complicated process is required for manufacturing the motor, thereby increasing manufacturing cost thereof. 
     In view of the problems described above, an object of the present invention is to provide a reverse electromotive force generating motor (a motor) with a rotor functioning as both a motor and an electric generator. The motor changes a direction of a reverse electromotive force generated at a fixed coil thereof before the reverse electromotive force reaches an inverter, thereby resolving the problems described above. 
     Further objects and advantages of the invention will be apparent from the following description of the invention. 
     SUMMARY OF THE INVENTION 
     In order to attain the objects described above, according to the present invention, a reverse electromotive force generating motor includes a stator yoke; a rotor disposed in the stator yoke; a first coil disposed in the stator yoke and connected to a first input line of a power source with a first phase; a second coil disposed in the stator yoke and connected to the first coil in series, the second coil being connected to a neutral point; a third coil disposed in the stator yoke and connected to the first input line; a fourth coil disposed in the stator yoke and connected to the third coil in series, the fourth coil being connected to a first output line for outputting power; and a rotational shaft disposed in the rotor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view showing a reverse electromotive force generating motor according to a first embodiment of the present invention; 
         FIG. 2  is a sectional view showing a stator yoke of the reverse electromotive force generating motor according to the first embodiment of the present invention; 
         FIG. 3  is a circuit diagram of the reverse electromotive force generating motor according to the first embodiment of the present invention; and 
         FIG. 4  is a circuit diagram of a reverse electromotive force generating motor according to a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereunder, embodiments of the present invention will be explained with reference to the accompanying drawing. 
     First Embodiment 
     A first embodiment of the present invention will be explained.  FIG. 1  is a sectional view showing a reverse electromotive force generating motor according to the first embodiment of the present invention. 
     As shown in  FIG. 1 , the reverse electromotive force generating motor includes a stator yoke  30 ; a rotor  40  disposed in the stator yoke  30 ; and a rotational shaft  50  disposed in the rotor  40 . 
     As shown in  FIG. 1 , the stator yoke  30  has a plurality of slots  1  to  24  (twenty four slots in the embodiment) as hollow portions. A plurality of coils  101  to  103 ,  201  to  203 ,  301  to  303 , and  401  to  403  (described later) is arranged in the slots  1  to  24  for generating an electromotive force around the stator yoke  30 , so that the rotor  40  is attracted and rotates around the rotational shaft  50 . 
       FIG. 2  is a sectional view showing the stator yoke  30  of the reverse electromotive force generating motor according to the embodiment of the present invention. The stator yoke  30  is a four-pole type, an arrangement of the coils  101  to  103 ,  201  to  203 ,  301  to  303 , and  401  to  403  will be explained below. 
     As shown in  FIG. 2 , the stator yoke  30  is a four-pole type, and has twenty four slots for winding the coils  101  to  103 ,  201  to  203 ,  301  to  303 , and  401  to  403 . Alternatively, the stator yoke  30  may have forty eight slots. When a stator yoke is a six-pole type, the stator may have thirty six slots. 
     In the embodiment, the coils  101  to  103 ,  201  to  203 ,  301  to  303 , and  401  to  403  are arranged in the slots  1  to  24  as follows. The coil  101  is disposed in the slots  1  and  6 , and is connected to an input line of a first phase. The coil  301  is disposed in the slots  13  and  18 , and is connected to the coil  101  in the input line of the first phase. The coil  201  is disposed in the slots  7  and  12 , and is connected to an output line of the first phase. The coil  401  is disposed in the slots  19  and  24 , and is connected to the coil  201  in the output line of the first phase. 
     In the embodiment, the coil  102  is disposed in the slots  5  and  10 , and is connected to an input line of a second phase. The coil  302  is disposed in the slots  17  and  22 , and is connected to the coil  102  in the input line of the second phase. The coil  202  is disposed in the slots  11  and  16 , and is connected to an output line of the second phase. The coil  402  is disposed in the slots  23  and  4 , and is connected to the coil  202  in the output line of the second phase. 
     In the embodiment, the coil  103  is disposed in the slots  9  and  14 , and is connected to an input line of a third phase. The coil  303  is disposed in the slots  21  and  2 , and is connected to the coil  103  in the input line of the third phase. The coil  203  is disposed in the slots  15  and  20 , and is connected to an output line of the third phase. The coil  403  is disposed in the slots  3  and  8 , and is connected to the coil  203  in the output line of the third phase. 
     In the embodiment, the coils  101  to  103 ,  201  to  203 ,  301  to  303 , and  401  to  403  are connected as follows.  FIG. 3  is a circuit diagram of the reverse electromotive force generating motor according to the embodiment of the present invention. 
     As shown in  FIG. 3 , a power source has three input lines of three phases. The input line of the first phase is connected to the coil  101  at a connection point A, and the coil  101  is connected to the coil  301  in series. The input line of the second phase is connected to the coil  102  at a connection point B, and the coil  102  is connected to the coil  302  in series. The input line of the third phase is connected to the coil  103  at a connection point C, and the coil  103  is connected to the coil  303  in series. The coils  301 ,  302 , and  303  are connected at a neutral point D. 
     Further, in the embodiment, three output lines are connected to the connection points A to C. The output line of the first phase is connected to the coil  201  at the connection point A, and the coil  201  is connected to the coil  401  in series. The output line of the second phase is connected to the coil  202  at the connection point B, and the coil  202  is connected to the coil  402  in series. The output line of the third phase is connected to the coil  203  at the connection point C, and the coil  203  is connected to the coil  403  in series. 
     An operation of the reverse electromotive force generating motor will be explained. In the following description, the first phase line of the reverse electromotive force generating motor of the four-pole type will be explained as an example. The second and the third phase lines rotate and generate electric power in the same way. 
     The motor reverse electromotive force generating rotates with a three-phase alternate current of 200 V. A magnetic field is generated at the coils  101 ,  201 ,  301 , and  401  in the first phase line. The magnetic field thus generated attracts permanent magnets of the rotor  40 , thereby rotating the rotor  40 . 
     More specifically, the coil  101  and the coil  301  in the first phase line generate the magnetic field of an S pole in the stator yoke  30 , and the coil  201  and the coil  401  in the first phase line generate the magnetic field of an N pole in the stator yoke  30 . 
     When a voltage applied to the coil  101  and the coil  301  in the first phase line becomes zero, the coil  102  and the coli  302  in the second phase line generate the magnetic field of the S pole. Further, the coil  202  and the coli  402  in the second phase line generate the magnetic field of the N pole. Accordingly, the permanent magnets of the rotor  40  are attracted to the magnetic field, thereby rotating the rotor  40 . 
     When the rotor  40  rotates as described above, a magnetic flux of the N pole traverses the coil  101  and the coil  301 , thereby generating the reverse electromotive force. At the same time, a magnetic flux of the S pole traverses the coil  201  and the coil  401 , thereby generating the electromotive force. At this moment, a reverse electromotive current flows toward the input line, and an electromotive current flows toward the output line. 
     In the embodiment, the coil  101  and the coil  201  are connected to the connection point A. Accordingly, the reverse electromotive current eventually flows toward the output line as an alternate current reverse current. As a result, it is possible to generate alternate current power. 
     Second Embodiment 
     A second embodiment of the present invention will be explained next. In the second embodiment, the coils  101  to  103 ,  201  to  203 ,  301  to  303 , and  401  to  403  are arranged in the slots  1  to  24  of the stator yoke  30  in the same way as that in the first embodiment. 
       FIG. 4  is a circuit diagram of a reverse electromotive force generating motor according to the second embodiment of the present invention. 
     As shown in  FIG. 4 , a power source has three input lines of three phases. The input line of the first phase is connected to the coil  101  at a connection point A, and the coil  101  is connected to the coil  301  in series. The input line of the second phase is connected to the coil  102  at a connection point B, and the coil  102  is connected to the coil  302  in series. The input line of the third phase is connected to the coil  103  at a connection point C, and the coil  103  is connected to the coil  303  in series. 
     In the embodiment, the coil  301  is connected to the coil  102  at a neutral point D. Similarly, the coil  302  is connected to the coil  103  at a neutral point D, and the coil  303  is connected to the coil  101  at a neutral point D. In other words, in the embodiment, there are three neutral points D. 
     Further, in the embodiment, three output lines are connected to the connection points A to C. The output line of the first phase is connected to the coil  201  at the connection point A, and the coil  201  is connected to the coil  401  in series. The output line of the second phase is connected to the coil  202  at the connection point B, and the coil  202  is connected to the coil  402  in series. The output line of the third phase is connected to the coil  203  at the connection point C, and the coil  203  is connected to the coil  403  in series. 
     An operation of the reverse electromotive force generating motor in the second embodiment is similar to that in the first embodiment, and a detailed explanation thereof is omitted. 
     The disclosure of Japanese Patent Application No. 2009-204311, filed on Sep. 4, 2009 is incorporated in the application by reference. 
     While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.