US 5,483,139 A · Motor start, reverse and protection system without a starting capacitor

Abstract

A single phase induction motor includes a start winding, a run winding coupled in parallel with the start winding, a start switch, and a run switch. A control circuit is provided for selectively supplying voltage to the start and run windings. A current sensor is coupled to the control circuit and the start and run windings for estimating the temperature rise of the motor and turning the motor off if overheated. An alternating voltage having a plurality of 360.degree. cycles can be continuously applied to the run winding through the run switch. The alternating voltage is repetitively applied through the start switch to the start winding in the range of 45.degree. to 135.degree. into each respective one of the plurality of cycles and ending at approximately 180.degree. into each respective cycle and beginning in the range of 225.degree. to 315.degree. into each respective cycle and ending at approximately 360.degree. into each respective cycle until the motor is running at a speed close to synchronous speed.

Claims30

Dependent claims

A single phase induction motor without a starting capacitor, the motor comprising:

a start winding;
a run winding coupled in parallel with said start winding;
a start switch;
a run switch;
a control circuit for selectively supplying unphase-shifted line voltage to said start and run windings by controlling said start and run switches, said start switch being coupled between said start winding and said control circuit and said run switch being coupled between said run winding and said control circuit;
and
a current sensor coupled to said control circuit and said start and run switches for measuring current values in said start and run windings and supplying said current values to said control circuit.

4 more elements

A method for starting a single phase induction motor having first and second windings and no starting capacitor, comprising the steps of:

repetitively providing a sequence including,
applying an alternating unphase-shifted line voltage to a first winding for a duration of a first fraction of a cycle;
applying said alternating unphase-shifted line voltage to a second winding for a duration of a second fraction of said cycle;
and
providing an interval in which neither winding receives alternating voltage for a duration of a third fraction of said cycle;
and
thereafter continuously applying said alternating voltage to said first winding.

4 more elements

Dependencies are inferred from the claim text.

Motor start, reverse and protection system without a starting capacitor

Life of this patent

Motor start, reverse and protection system without a starting capacitor

Life of this patent

Abstract

Claims30