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Variable speed variable torque brushless DC motor

  • US 4,897,583 A
  • Filed: 03/07/1989
  • Issued: 01/30/1990
  • Est. Priority Date: 03/07/1989
  • Status: Expired due to Fees
First Claim
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1. A variable speed variable torque brushless DC motor having a rotor, stator windings, and at least one rotor position sensor with each position sensor producing a position signal indicating position of the rotor and having a frequency equal to a frequency of excitation current applied for activating the stator windings of the motor, comprising:

  • a pulse generator, responsive to the at least one position sensor, for producing first pulses having a frequency which is equal to nf where n is the number of position sensors and f is the frequency of excitation current;

    a source of a first signal having a frequency f1 wherein f1 >

    f;

    a source of a variable frequency second signal having a frequency f2 with f2 ≧

    fl;

    an excitation circuit for applying excitation current pulses to the stator windings with the excitation current pulses occurring in response to the position signals produced by the at least one position sensor; and

    a delay circuit, responsive to the first pulses, the first signal, and the second signal for delaying application of the position signals to the excitation circuit with the delay being equal to mf1/mf2 wherein m is an integer.

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