Pt Components, Inc.

Rexnard Corporation

Victor A Murn

Steven F Chmiel

Richard A Wrege

Joseph S Bossi

Dennis K Lorenz

In an AC motor having a main winding connectable to an AC power source for supplying running torque, and having a start winding connectable to the AC power source for supplying starting torque, a start switch is provided for connecting and disconnecting the start winding from the AC power source in starting and running modes, respectively. A main winding voltage phase detector detects the phase of voltage across the main winding. A start winding current phase detector detects the phase of current through the start winding during the starting mode. A cut-out circuit responds to the main winding voltage phase detector and to the start winding current phase detector.

Phase detector motor start switch

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 dual comparator chip (20, 22) senses and compares relative magnitudes of AC line and auxiliary winding voltages (48, 40) to de-energize the auxiliary winding (2) at cut-out speed, and automatically re-energize the auxiliary winding at cut-in speed to accelerate or restart the motor from an overload or stall condition. Hysteresis circuitry (20, 50, 52, 57, 80) provides a lower cut-in speed than cut-out speed. Simplified power supply and voltage detection circuitry is also disclosed.

Motor starting circuit with low cost comparator hysteresis

In a single phase AC induction motor having a main winding (1) and an auxiliary winding (2) both connectable to an AC power source (4), and having a start switch (6, 74) for automatically connecting and disconnecting the auxiliary winding (2) to and from the AC source (4) in starting and running modes, respectively, and having a user operated reversing switch (207-212) for reversing the voltage polarity applied from the AC source (4) to one of the windings relative to the other winding, low cost circuitry is provided for detecting the polarity reversal by sensing when one of the main and auxiliary winding voltages shifts from a leading to a lagging position relative to the other winding voltage, whereupon the circuit automatically instantly reconnects the auxiliary winding (2) to the AC source (4) to immediately apply reverse torque. A first voltage comparator (221) senses a given polarity and magnitude of main winding voltage, and a second voltage comparator (222) senses a given polarity and magnitude of auxiliary winding voltage. The output of the second comparator (222) is differentiated (282), and a third voltage comparator (223) compares output pulses (270) from the first comparator (221) and differentiated output pulses (288) from the second comparator (222) and instantaneously senses polarity reversal when one of the pulses shifts relative to the other, and in turn actuates the start switch (6, 74).

Low cost instant reversing circuit

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.

Growing community of inventors

Muskego, WI, United States of America

Victor A Murn