Circuit arrangement for thyristor-controlled rotation-speed regulation, without a rectifier, for low-voltage DC motors, for operation on AC voltage

摘要

The invention relates to a circuit arrangement for thyristor-controlled rotation-speed regulation, without a rectifier, of low-voltage DC motors, for operation on AC voltage, which circuit arrangement is characterised in that the back e.m.f. of the motor to be controlled is supplied, after conditioning in a regulating-voltage stage and via a potentiometer for setting the rotation speed, to the non-inverting input of a differential comparator stage whose output is connected via in each case one driver stage (which is connected to a reference-voltage source) to the gates of two thyristors which are connected from the secondary-winding ends of a transformer to the junction point to the motor, and in that the secondary voltage of the transformer is supplied via diodes to a ramp generator whose output is connected to the inverting input of the differential comparator stage, the voltage obtained via the diodes being used to form the reference source and for automatic zero-point tracking, which is connected to the ramp generator.