Patent ID: 6160372
Filing Date: 2000-12-12
Classification: H02P

Abstract:
A motor starter circuit for an AC electric motor having a run winding, a first start winding and a second start winding, said circuit comprising:a run winding current sensor;a sensor switch having an input coupled to said current sensor and having an output;a controller having a controller input coupled to said sensor switch output and having a first controller output and a second controller output and including a phase detector responsive to a phase shift of a signal applied at said controller input;a first starter switch responsive to and output of said phase detector and having a first starter switch input coupled to said first controller output and having a first starter switch output coupled to said first start winding; anda second starter switch responsive to an output of said phase detector and having a second starter switch input coupled to said second controller output and having a second starter switch output coupled to said second start winding,wherein said sensor switch includes a semiconductor switch biased with a signal containing a ripple component derived from an AC voltage applied to said run winding wherein said ripple component is phased shifted approximately 90 degrees from said AC voltage.