Induction motor starting and speed controller - operates with thyristor switching in rotor circuit and rotor voltage is used as feedback signal

摘要

The object of the control unit is to allow a soft start of the motor and to control the speed, or torque, delivered by the motor when running. The control circuit uses the rotor voltage as a feedback signal which is evaluated in a comparator (7) against a reference (6). The rotor voltage is also converted into an amplitude limited sawtooth wave in a generator (4), which is also supplied with a speed signal. The comparator (7) output is used to control the triggering pulse generator (8) which governs the conduction of the thyristors (9) in the rotor load circuit.