| 摘要 |
PURPOSE:To readily brake a motor with a reverse phase driving voltage even when the rotating speed of the motor is low to extremely low speed by switching the energizing direction of the driving voltage supplied to the motor on the basis of the comparison of the detecting frequency with an instruction frequency. CONSTITUTION:An error amplifying circuit 9 serves to apply a driving voltage responsive to the error difference between the detected rotating speed from a frequency-to-voltage converting circuit 4 and an instruction rotating speed from a frequency-to-voltage converting circuit 5 to a motor 1. A frequency comparing circuit 10 serves to compare the detected frequency Fm responsive to the detected rotating speed with an instruction frequency Fc responsive to the instruction rotating speed, and controls to switch the current flowing direction of the motor 1 so as to supply a reverse phase driving voltage to the motor when Fm>Fc and to supply a normal phase driving voltage to the motor 1 when Fm<Fc. In this case, the arrangement is so constructed that Fc>Fm is obtained when the detected rotating speed becomes coincident to the instruction rotating speed. |
