| 摘要 |
A brushless motor comprising: a rotor constituted by a permanent magnet having a plurality of circumferentially alternately equally magnetized N and S magnetic poles; a stator having a plurality of excitation coils equidistantly disposed around the rotor; a rotor position detecting member such as a magneto-sensitive element; and a printed circuit board having a commutation circuit for switching the electric current for the excitation coils based on a detection signal of the rotor position detecting member; wherein the number of the magnetic poles of the rotor is selected so that the number of the magnetic poles of the rotor located within an area between respective center lines of two adjacent excitation coils is an odd number not smaller than three. The width of each excitation coil is selected so that an angle alpha formed between lines connecting the circumferential opposite ends of each excitation coil commonly to a center of the rotor is made equal to an angle beta formed between lines connecting the circumferential opposite ends of each magnetic pole of the rotor commonly to the center of the rotor.
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