| 摘要 |
PURPOSE:To eliminate noise produced by a large commutation of exciting current in a machine in which the period information of signal induced in the exciting coil of a commutator-less motor is used as a speed signal, by processing the speed signal by a position signal. CONSTITUTION:A commutator-less motor has exciting coils Ma to Mc which are successively energized by electric current supplied from transistors 8 to 10 adapted to be successively turned on by signals d to f derived from a position signal generator 29. A rotor constituted by a permanent magnet is rotated as a result of the energization of the exciting coils Ma to Mc. In each exciting coil, induced are a first spike voltage generated by mutual induction when the exciting current is commutated in another phase and a second spike voltage generated when the current of its own phase is cut. These spike voltage are shaped by circuits 11 to 13 and flip-flops 14 to 16 are set by the first spike voltage. The flip-flops are then reset by the position signal e from the phase next to the first-mentioned phase which produces an output h. Therefore, no second spike voltage appears in the output i. Then, a speed pulse k is produced by monostable multivibrators 17 to 19. The speed pulse is converted into voltage through an f-v conversion by a circuit 22, and a speed control is effected by a circuit 23. |
