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Speed control systems of synchronous motors

  • US 4,384,242 A
  • Filed: 06/03/1981
  • Issued: 05/17/1983
  • Est. Priority Date: 06/12/1980
  • Status: Expired due to Term
First Claim
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1. A speed control system of a synchronous motor provided with a plurality of stator windings which are displaced electrically and mechanically by predetermined angles and a rotor, comprising:

  • means driven by said rotor for producing a phase modulated signal E sin (ω

    t+θ

    ), where E represents voltage, ω

    =2π

    f, θ

    represents a rotational angle of said motor and f a frequency;

    speed signal converting means which forms a signal corresponding to a differential of said rotational angle;

    means for producing a speed instruction signal corresponding to a rotational speed of said rotor;

    means for producing an error signal corresponding to a difference between said signal formed by said speed signal converting means and said speed instruction signal;

    a multiplier for multiplying said phase modulated signal with said error signal;

    means for producing a plurality of reference signals having a phase difference of said predetermined angles; and

    synchronous rectifier means for rectifying an output of said multiplier according to said reference signals for producing currents supplied to said stator windings of said motor.

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