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Brushless motor drive circuit having a highly accurate sinusoidal output signal

  • US 5,155,419 A
  • Filed: 10/16/1990
  • Issued: 10/13/1992
  • Est. Priority Date: 10/19/1989
  • Status: Expired due to Fees
First Claim
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1. In a motor drive circuit for driving a brushless motor having a rotor magnet with 2n (n=integer) magnetized poles, drive coils with m (m=integer) different phases for rotatively driving said rotor magnet and where a total of k (k=integer) locating means are employed for detecting the rotary position of said rotor magnet and for generating output signals representing the detected position, the circuit further comprising a total of m controlling and multiplying means each responsive to the output signal from the corresponding one of said k locating means at one of its input terminals, m output amplifying means, each for receiving the output signal from the corresponding one of said m controlling and multiplying means to provide m output voltages to drive said drive coils, m repetitive computing means for repetitively multiplying each of the output signals from the m output amplifying means by itself until the sum of the powers of the output signals reaches a given value, the exponent of the repetitive multiplication being an even number, and a control section for feeding back the output voltages from the m repetitively computing means to the other input terminals of each of said m controlling and multiplying means in order to provide highly accurate sinusoidal driving voltages to said motor.

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