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METHOD AND MEANS FOR LIMITING THE MAXIMUM HORSEPOWER OUTPUT OF A SELF-EXCITED ALTERNATING CURRENT MOTOR

  • US 3,769,564 A
  • Filed: 08/30/1972
  • Issued: 10/30/1973
  • Est. Priority Date: 08/30/1972
  • Status: Expired due to Term
First Claim
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1. A motor control interposable between an electrical energy source and the stator winding of a self-excited alternating current induction motor for controlling the torque developed by the motor and for limiting the maximum horsepower output of the motor, said control comprising:

  • a. first signal means for generating a torque command signal indicative of the desired motor output torque condition;

    b. second signal means coupled to the alternating current motor for providing a signal indicative of the rotor frequency of the motor rotor;

    c. frequency control means connectable to the stator winding of the motor for energizing the stator winding with a cyclical current, said frequency control means being coupled to said second signal means for establishing the frequency of the cyclical current in accordance with said rotor frequency signal, said frequency control means being further coupled to said first signal means for altering the established frequency of the cyclical current and the slip frequency of the motor in accordance with the torque command signal;

    d. power supply means connectable to the electrical energy source and coupled to said frequency control means for providing a regulatable current to the frequency control means, said power supply means being coupled to said first signal means for regulating the magnitude of the stator current as a predetermined function of the torque command signal; and

    e. means for limiting the output horsepower, said limiting means having an input coupled to the stator winding to receive the stator voltage and an output limiting command signal coupled to said frequency control means, said limiting command signal indicative of a rotor frequency and horsepower output in excess of a predetermined value, said frequency control means responding to said limiting command signal by increasing the slip frequency to maintain a maximum horsepower output and torque per ampere.

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