Two-phase brushless dc motor

Abstract

A brushless motor includes a two-phase winding stator having 4×n winding poles and auxiliary poles provided between the winding poles, and a rotor constituted by 6×n permanent magnet rotating poles having divided angle. The two-phase brushless motor can be driven by a control device for the two-phase motor which can transform electric power and rectify electronically. The two-phase brushless DC motor can increase a permeance coefficient of the rotor, improve the efficiency and the starting of the motor, and reduce torque ripple and noise thereof.

1 . A 2-phase brushless DC motor comprising:
 a rotor comprising 6×n permanent magnet poles;   a stator comprising 4×n electromagnetic poles and 4×m auxiliary poles, wherein ‘n’ is an integer greater than zero, and ‘m’ is an integer greater than zero, wherein the 4×n electromagnetic poles comprises first and second electromagnetic poles, which are immediately neighboring among the 4×n electromagnetic poles, wherein at least one of the 4×m auxiliary poles being interposed between the first and second electromagnetic poles;   a first winding associated with the first electromagnetic pole;   a second winding associated with the second electromagnetic pole; and   a circuit configured to provide a first electrical signal to the first winding and a second electric signal to the second winding, whereby the 6×n permanent magnet poles of the rotor are magnetically interact with the 4×n electromagnetic poles and the 4×m auxiliary poles.   
     
     
         2 . The motor of  claim 1 , wherein each of the 4×n electromagnetic poles has an angular width generally corresponding to an angular width of one of the 6×n permanent magnet poles of the rotor. 
     
     
         3 . The motor of  claim 1 , wherein each of the 4×m auxiliary poles has an angular width generally corresponding to one half an angular width of one of the 6×n permanent magnet poles of the rotor. 
     
     
         4 . The motor of  claim 1 , wherein ‘n’ is 1, wherein each electromagnetic pole has an angular width of about 60°. 
     
     
         5 . The motor of  claim 1 , wherein ‘m’ is 1, wherein each auxiliary pole has an angular width of about 30°. 
     
     
         6 . The motor of  claim 1 , wherein two immediately neighboring auxiliary poles among the 4×m auxiliary poles are apart from each other with an angular gap generally corresponding to an angular width of each permanent magnet pole of the rotor. 
     
     
         7 . The motor of  claim 1 , wherein the first and second electromagnetic poles are apart from each other with an angular gap generally corresponding to one half an angular width of each permanent magnet pole of the rotor. 
     
     
         8 . The motor of  claim 1 , wherein each permanent magnetic pole has a substantially identical angular width about a rotational axis of the rotor. 
     
     
         9 . The motor of  claim 1 , wherein the first electric signal comprises a first waveform having a first period, wherein the second electric signal comprises a second waveform having a second period substantially the same as the first period, wherein the first and second electric signals have a phase difference of about ¼ of the first cycle. 
     
     
         10 . The motor of  claim 1 , wherein the first electric signal comprises a first waveform having a first period, wherein the second electric signal comprises a second waveform having a second period substantially the same as the first period, wherein the first and second electric signals have a phase difference of about 30°. 
     
     
         11 . The motor of  claim 1 , wherein the first electric signal comprises a first waveform having 3×n cycles per revolution of the rotor. 
     
     
         12 . The motor of  claim 1 , wherein the electric motor further comprises:
 a first sensor positioned adjacent to the first electromagnetic pole and configured to detect the rotor's position relative to the first electromagnetic pole; and   a second sensor positioned adjacent to the second electromagnetic pole and configured to detect the rotor's position relative to the second electromagnetic pole.   
     
     
         13 . The motor of  claim 1 , wherein the 4×n electromagnetic poles further comprises third and fourth electromagnetic poles, wherein a third winding is associated with the third electromagnetic pole and electrically connected to the first winding, wherein a fourth electromagnetic pole is associated with the fourth electromagnetic pole and electrically connected to the second winding. 
     
     
         14 . The motor of  claim 13 , wherein the first and third electromagnetic poles are opposingly arranged with each other, wherein the second and fourth electromagnetic poles are opposingly arranged with each other. 
     
     
         15 . The motor of  claim 1 , wherein the electromagnetic poles and the auxiliary poles are integrated in a single piece. 
     
     
         16 . The motor of  claim 1 , wherein ‘n’ is identical to ‘m’. 
     
     
         17 . The motor of  claim 16 , wherein the electromagnetic poles and auxiliary poles are alternatingly arranged. 
     
     
         18 . The motor of  claim 1 , wherein the 4×m auxiliary poles comprises a first auxiliary pole positioned immediately next to the first electromagnetic pole, wherein the first auxiliary pole is angularly spaced from the first electromagnetic pole. 
     
     
         19 . The motor of  claim 1 , wherein each auxiliary pole does not comprise a winding that carries an electric signal while operating the motor. 
     
     
         20 . The motor of  claim 1 , wherein each auxiliary pole comprises a tapered portion tapered in a radial direction of the rotor and has an angular width of about 30° throughout the tapered portion from a distal end to a proximal end thereof.