| 摘要 |
1,197,459. Automatic speed control. ERESA S.A. Sept.19, 1967 [Sept. 29, 1966], No. 42635 / 67. Heading G3R. An electric motor M is controlled from a source 1 which supplies a reference signal whose frequency represents the desired speed of the motor, an alternator 2 being driven by the motor to supply a signal the frequency of which is proportional to the actual speed. The phase relationship between the two signals is detected to form two position signals which are equal when the motor is in a required angular position. When starting, the motor is accelerated until the two speed signals are equalized, the motor being then controlled by the difference between the position signals which determines the magnitude of the applied voltage. The amplitude of a signal t varies in dependence upon the frequency of the motor signal m, and in accordance with the adjustment of potentiometer R. A differential amplifier 5 compares the signal t with a reference signal to, the error signal C being amplified to control the supply to the motor. A phase control circuit 7 derives position signals P2, P1, from the motor signal m and the reference signal f supplied by the source 1. The signals P1, P2, are equal when the frequencies of the signals m, f, are identical, and these two signals are 90 degrees out of phase. The signals P1, P2 are respectively superimposed on the signals to, t, before they are applied to the comparator circuit 5, and become predominant when the speed approaches the desired value. In another arrangement, the reference signal f is made to vary with time, this signal being fed to a trigger circuit in series with a monostable multi-vibrator and an integrator the output of which is the signal to whose magnitude varies in accordance with the frequency of the signal f. A similar network supplies the signal t in response to the input signal m, Fig. 2 (not shown). An alarm device is energized if one of the signals m or f is blocked, and a relay is deenergized to stop the motor, Fig. 3 (not shown). |
