×

Clock rate control of electronically commutated motor rotational velocity

  • US 4,250,435 A
  • Filed: 01/04/1980
  • Issued: 02/10/1981
  • Est. Priority Date: 01/04/1980
  • Status: Expired due to Term
First Claim
Patent Images

1. A speed control system for an electronically commutated motor having a rotor and a plurality of stator windings operable to produce magnetic fields in response to selective winding energization, said system comprising:

  • a commutation sequencer operable to selectively energize the motor windings in a sequence appropriate for effecting motor rotor rotation, said commutation sequencer operable to advance step-by-step through the sequence as the rotor reaches each of a plurality of predetermined positions;

    a storage device for storing a changeable representation of an established limit for motor winding current;

    a controller responsive to said representation for limiting current through motor windings energized by said sequencer to the established limit;

    a sensor for determining actual rotor position;

    a source of periodic signals representative of desired rotor position and occurring at a rate proportional to desired rotational velocity, the time of occurrence of each individual one of the periodic signals representative of a particular instantaneous desired rotor position; and

    and adjustment element responsive to said sensor and to said periodic signal source, said adjustment element operable to periodically compare actual rotor position to desired rotor position and to decrease the established limit for motor winding current in the event actual rotor position leads desired rotor position by at least a predetermined amount, and to increase the established limit for motor winding current in the event actual rotor position lags desired rotor position by at least a predetermined amount.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×