Universal or series wound motor speed control - is esp. for domestic machines and uses phase controlled thyristors triggered by capacitor

摘要

The speed control is for DC series wound or universal motors esp. those normally in household use. The control maintains motor speed in spite of load variation without alteration of the circuit resistance. A thyristor or thyristors in series with the motor is/are supplied with interrupted DC whose value is a function of the motor load couple. The thyristor is triggered from a capacitor as part of a phase controlled firing circuit adjustable by a variable resistor. The capacitor is charged via a diode and resistance from the motor circuit such that its charge is a function of the phase angle of the motor current or is charged from a combination of several resistors from the negative terminal of a bridge rectifier.