Controller

摘要

1,106,800. Control of D.C. motors. NEW YORK AIR BRAKE CO. 7 Feb., 1967 [3 March, 1966], No. 5698/67. Heading H2J. A series motor 11 is supplied from A.C. mains L1, L2, through triac 13 which is triggered by diac 15 associated with timing circuit 16. Voltage pulses in synchronism with the A.C. power are supplied to the timing circuit from generator 17 through a resistor 181 across which is developed a variable control voltage. The speed of the motor and its direction of rotation are determined by the magnitude and polarity of the control voltage. The motor is adapted to vibrate about a null position when the control voltage is zero. A pair of Zener diodes 24 and current-limiting resistor 24a are connected across leads L1, L2, to render the voltage of generator 17 independent of fluctuations in the power lines. The triac 13 may be replaced by a pair of silicon controlled rectifiers in a bridge circuit which also comprises diodes. The silicon controlled rectifiers are gated by pulses from a transformer having the diac 15 in its primary circuit. A step-down transformer may be used to reduce the voltage applied to the pulse generator, the secondary circuit of this transformer comprising a limiting resistor associated with a Zener diode which forms part of a bridge rectifier network.