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Method and apparatus for controlling an electric assist motor

  • US 6,008,599 A
  • Filed: 09/20/1996
  • Issued: 12/28/1999
  • Est. Priority Date: 11/04/1994
  • Status: Expired due to Term
First Claim
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1. An apparatus for controlling an electric motor comprising:

  • a first switching device operatively coupled between one terminal of said electric motor and a first terminal of a source of electrical energy;

    a second switching device operatively coupled between a second terminal of said electric motor and a second terminal of said source of electrical energy; and

    control means for controlling energization of said electric motor, said control means including means for periodically switching both said first and second switching devices between ON and OFF conditions during a motor commutation period, the switching period of said first and second switching devices being less than the motor commutation period and each said first and second switching devices having more than one ON condition during the motor commutation period and only a portion of each of the ON conditions of the first and second switching devices overlap during the switching period, electrical current flows through said electric motor during each overlap portion of the ON conditions and power dissipation switching losses are shared by both said first and second switching devices, the amount of the ON condition overlap controlling current in said electric motor, said control means including means for controlling said ON condition overlap.

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