| 摘要 |
PURPOSE:To obtain speed detection signals with low ripple by deciding a frequency from rotary position detection signals wherein a frequency-voltage converter deciding a reference voltage by the output from an armature voltage detection circuit is provided. CONSTITUTION:A frequency converter section 7 converts signals from a rotary position detector 5 into three or sixfold pulses A. A contactless switch 8 in an integrating circuit is closed when the output A is at high level and opened at low level output. The integrating circuit integrates the output Ea from an armature voltage detection circuit 15 to feed signals B. A comparator 12 compares the signals B with a constant voltage (e) to feed pulse signals C having time width T. A contactless switch 13 is closed when the signals C are at high level. In this way, signals D before passing through a filter 14 become ones having voltage height and time proportinating to an armature voltage Ea to minimize a ripple value. |
