| 摘要 |
PROBLEM TO BE SOLVED: To provide a rotation detecting device for highly accurately detecting a rotation angle in stopping of a DC motor with a brush, whose rotation state can be detected, irrespective of the magnitude of a DC component of a motor current without providing a sensor; and to provide a DC motor device. SOLUTION: The motor includes a variable mechanism in which reactance between brushes periodically changes in accordance with rotation. A power supply voltage obtained by superimposing an AC voltage over a DC voltage is applied to the motor. A motor controller turns a braking command signal to "H" in short circuit braking the motor, and if a detection pulse generated from an AC component after the motor current passes HPF is "H", Q-output of a flip-flop becomes "H", and short circuit braking starts. At this point, a surge current 300 occurs in the motor current and a component 302 of the surge current 300 is detected during a period when the amplitude of the AC component after HPF is large. The component 302 is absorbed as shown by a dotted line 304 during the "H" period of the detection pulse, so that a new pulse signal is not generated due to the surge current. COPYRIGHT: (C)2011,JPO&INPIT
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