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Motor apparatus using PWM drive currents

  • US 4,491,771 A
  • Filed: 01/05/1983
  • Issued: 01/01/1985
  • Est. Priority Date: 03/07/1980
  • Status: Expired due to Fees
First Claim
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1. A motor apparatus comprising:

  • a motor including a rotor and exciting coils;

    detection means coupled to said motor for providing first and second detection signals corresponding to the rotational speed of said rotor;

    amplifier means coupled to said detection means for providing first and second output signals, said first output signal corresponding to said first detection signal and said second output signal corresponding to said second detection signal;

    a first comparator for comparing said first output signal with a first threshold level to provide a first pulse signal;

    a second comparator for comparing said first output signal with a second threshold level to provide a second pulse signal;

    a third comparator for comparing said second output signal with said second threshold level to provide a third pulse signal;

    a fourth comparator for comparing said second output signal with said first threshold level to provide a fourth pulse signal;

    means coupled to said comparators for generating a reference level and for producing said first and said second threshold levels based on said reference level, and means for changing said reference level in accordance with a desired motor operating condition;

    control means responsive to the first output signal of said amplifier means and coupled in negative feedback relation to said changing means for maintaining said desired motor operating condition; and

    driver means coupled to said comparators for applying currents to said exciting coils of said motor in accordance with said first through fourth pulse signals, respectively.

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