| 摘要 |
PROBLEM TO BE SOLVED: To curtail the number of parts, and to increase efficiency of chip mounting by changing over the state of the currents of three-phase coils, on the basis of the polarity of electromotive force induced in a coil in a high- impedance state from among the three-phase coils. SOLUTION: Transition from a south pole to a north pole of a main magnetic pole being opposed to a U-phase coil 601, in a state (1) in which a current I is caused to flow from a W-phase coil 603 to a V-phase coil 602 through a neutral point N, for example, is detected on the basis of the polarity of electromotive force induced in the U-phase coil 601 which is in a high-impedance state. Consequently, the state of the current I caused to flow in the coils 601-603 is changed from the state (1) to a state (2). Following this, similar operation is performed. Namely, an output state is changed over, on the basis of the polarity of electromotive force induced in a coil in a high impedance state, from among the three-phase coils. Accordingly, a Hall element for detecting rotor position becomes unnecessary, and the number of parts is curtailed. Consequently, the efficiency of chip mounting can be improved. |
