| 摘要 |
PURPOSE:To determine appropriate dimensions of a magnet and others which enable attainment of stability of commutation of a logic circuit at the time of start, in a brushless DC motor wherein a wave form of the inductance of a winding relating to the position of a rotor is detected and the commutation is determined in the logic circuit. CONSTITUTION:In a brushless DC motor wherein a magnet 6 of a rotor 5 is disposed outside a stator core 4 having a winding 3, with a gap between them, the dimensional ratio of the outside diameter of the magnet 6 to the inside diameter thereof is made 1.10-1.15 and the dimensional ratio of the gap to the inside diameter of the magnet 6 is made 0.010-0.014, while the dimensional ratio of the length of the magnet 6 to that of the stator core 4 is made 1.45-1.55. Therefore the point of the minimum value of the inductance of a third winding corresponding to the position of the point at which the inductance of adjacent winding intersect each other is flat and logic circuit detects exactly the point at which the inductance of the adjacent winding intersect each other. |
