Starting control circuit for an A.C. motor

A digital starting control circuit for an alternating current motor having a run winding and a start winding and a mechanical rotational output comprising:

• an alternating current source;
• reference signal producing means for producing pulses having a reference frequency;
• first control means for counting the number of said reference pulses produced during a predetermined number of cycles of said alternating current source;
• sensor means for sensing a predetermined amount of rotational movement of said mechanical rotational output and producing sensor pulse indicative thereof;
• second control means for counting the number of said reference pulses produced during the time between a predetermined number of sensor pulses, and for comparing the counts in said first and second control means and assuming first and second output states dependent on the relationship between said counts;
• and
• switch means connected to said second control means, said alternating current source and said start winding for connecting and disconnecting said alternating current source and said start winding in response to the output state of said second control means.

A digital starting control circuit for an alternating current motor having a run winding and a start winding and a mechanical rotational output comprising:

• an alternating current source for delivering alternating current at a line frequency;
• reference signal producing means for producing pulses having a reference frequency;
• sensor means for sensing a predetermined amount of rotational movement of said mechanical rotational output and producing a sensor pulse indicative thereof;
• control means connected to said alternating current source, said reference signal producing means and said sensor means and operating independently of any particular line frequency and any particular reference frequency for assuming a first output state when the output speed of said mechanical rotational output is below a predetermined level and for assuming a second output state when the output speed of said mechanical rotational output exceeds said predetermined level;
• and
• switch means connected to said control means, said alternating current source and said start winding for connecting and disconnecting said alternating current source and said start winding in response to the output state of said control means.