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Control apparatus for brush-less motor

  • US 4,808,902 A
  • Filed: 05/23/1988
  • Issued: 02/28/1989
  • Est. Priority Date: 05/26/1987
  • Status: Expired due to Term
First Claim
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1. A control apparatus for a brush-less motor, comprising:

  • inverter means for energizing the brush-less motor;

    β

    control means for controlling an operation of said inverter means, in accordance with an internal control signal;

    detector means for detecting a counterelectromotive force generated by said brush-less motor, and providing an EMF signal representing said counterelectromotive force;

    PLL means for comparing a phase of said EMF signal with that of said internal control signal, and controlling said β

    control means by said internal control signal, such that a phase difference between said internal control signal and said EMF signal becomes minimal; and

    check means, coupled to said PLL means and said β

    control means, for checking an amount of the phase difference between said internal control signal and said EMF signal, and when a checked amount of the phase difference is found to have reached or exceeded a predetermined amount, modifying the operation of said β

    control means so that a commutation failure of said inverter means is prevented.

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