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Motor driver

  • US 6,812,667 B2
  • Filed: 02/24/2003
  • Issued: 11/02/2004
  • Est. Priority Date: 07/15/2002
  • Status: Expired due to Fees
First Claim
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1. A motor driver comprising:

  • (a) a driving coil of each one of three phases;

    (b) a dc power supply disposed between a first feeder line and a second feeder line;

    (c) a driving waveform generator for generating a driving waveform at intervals of one cycle in electrical angles corresponding to said driving coil;

    (d) a phase advancing controller for controlling a phase of the driving waveform; and

    (e) a power feeder for coupling said coils to one of the first feeder line and the second feeder line based on a pulse-width-modulated (PWM) signal modulated from the driving waveform, and for driving said coils with an alternating current (ac) consecutively changing, wherein said power feeder forms a first coupling status where a second-phase coil is coupled to the first feeder line and a first-phase and a third-phase coils are coupled to the second feeder line, and a second coupling status where the first-phase and the second-phase coils are coupled to the first feeder line and the third-phase coil is coupled to the second feeder line, wherein said phase advancing controller compares a common current in the first coupling status with the common current in the second coupling status, the common current running through one of the first feeder line and the second feeder line, and controls a phase of the driving waveform such that the common current values in the respective coupling statuses become approx. identical around a zero-cross of back electromotive force (BEMF) induced in the first-phase coil, and wherein the phase control by the phase advancing controller controls such that a phase of each one of the BEMFs of the respective phase-coils coincides with a phase of the ac running through the respective coils.

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