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Driving apparatus for brushless motor

  • US 4,900,993 A
  • Filed: 06/16/1988
  • Issued: 02/13/1990
  • Est. Priority Date: 06/17/1987
  • Status: Expired due to Term
First Claim
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1. A driving apparatus for a brushless motor having a plurality of driving coils for different phases, comprising:

  • switching means for switching voltages to said driving coils of said brushless motor,a switching signal generation circuit for controlling said switching means and for generating a switching signal,a phase difference detector for detecting a phase difference between a counter-electromotive voltage induced by one of said switching voltages in one of said plurality of driving coils and said switching signal in a time period that said induced voltage equals said one switching voltage,an amplifier for amplifying a detected signal of said phase difference detector and outputting an amplified signal, anda voltage-controlled oscillator for oscillating a signal controlled in frequency by said amplified signal and for supplying said oscillated signal to said switching signal generation circuit.

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