| 摘要 |
PURPOSE:To improve speed stability at low speed state, by a method wherein a frequency converter is installed to convert frequency of motor rotational speed detection pulse into higher frequency. CONSTITUTION: A rotational speed detector 8 generates pulse signals with frequency proportional to rotation speed of a motor 16. Frequency f of the pulse train is converted into frequency nf in a frequency converter 17, The output signal is transmitted qo a monostable flipflop circuit 9 and shaped into pulse with pulse width and amplitude being constant, and integrated in an integrating circuit 10 at next stage and converted into DC signal. A comparator ll compares the DC signal with DC voltage of a rotation speed setting means 12, and transmits the output signal to a control circuit 13. The control circuit 13 performs ON-OFF control of a triac 14 and controls power supply from a power source 15 to a motor 16. |
