Low cost, load and speed sensitive motor control starting circuit

摘要

A low cost, low part content single phase AC induction motor control starting circuit is provided which is speed sensitive, load sensitive and AC line voltage fluctuation insensitive. A quad comparator chip (61-64) senses and compares relative magnitudes of main and auxiliary winding voltages (30, 32 and 42) to de-energize the auxiliary winding (2) at cut- out speed, and automatically re-energize the auxiliary winding (2) at cut- in speed to accelerate or restart the motor from a stall or overload condition. Simplified power supply and voltage detection circuitry is also disclosed.