Motor controller and electric power steering system

  • US 8,471,504 B2
  • Filed: 03/30/2009
  • Issued: 06/25/2013
  • Est. Priority Date: 03/31/2008
  • Status: Active Grant
First Claim
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1. A motor controller configured to drive a brushless motor, said motor controller comprising:

  • a current detection unit configured to detect an electric current flowing through the brushless motor;

    an open loop control unit configured to determine a command value indicating a level of a command voltage for driving the brushless motor in accordance with a motor circuit equation, based on a command current value indicating an amount of electric current to be supplied to the brushless motor and an angular velocity of a rotor in the brushless motor;

    a correction unit configured to calculate a correction value based on a difference between the command current value and a current value detected by the current detection unit when the electric current is detected by the current detection unit and to correct the command value according to the calculated correction value, and to correct the command value according to the correction value even when an electric current is not detected by the current detection unit; and

    a motor drive unit configured to drive the brushless motor using a voltage having a level indicated by the command value corrected by the correction unit,wherein the motor drive unit comprises a switching circuit including a plurality of switching elements and configured to supply an electric current to the brushless motor.

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