| 摘要 |
PURPOSE: To increase the output torque constant of a brushless DC motor and decrease its torque ripple constant, by making the ratio of its magnetic-pole number to its salient-pole number specific in its permanent magnet, and by so forming the skew angle of its magnetic pole as to be represented as a specific electrical angle. CONSTITUTION: In a permanent magnet 9 of a brushless DC motor, the ratio of its magnetic-pole number to its salient-pole number is so formed as to be 1:3n (n is a natural number). For example, when the skew angle of its magnetic pole is represented as an electrical angle of 40 deg.-60 deg., a salient pole 31 is moved relatively from the position covered completely with one-pole (N pole) to the position covered completely with the neighboring one-pole (S pole), by the fact that a rotor 6 of the motor is rotated during the applying of a rectangular wave current to a coil 51. On the other hand, salient poles 32, 33 are moved relatively from the respective positions covered completely with respective one-poles to the respective positions covered completely with respective neighboring one-poles, by the fact that the rotor 6 is rotated during the applyings of respective rectangular wave currents to the coils 52. 53. Thereby, the motor is so controlled that three-phase rectangular wave currents each of which has the electrical angle of 120 deg. are applied in succession to the coils 51-53. |
