Patent ID: 6838844
Filing Date: 2005-01-04
Classification: B62D

Abstract:
1. An electric power steering apparatus comprising: steering torque detecting means for detecting a steering torque produced in accordance with operation of a steering wheel and generating a steering torque signal corresponding to the detected steering torque; a brushless motor PWM-driven with motor currents to apply a steering assist torque to a steering system, the motor currents being at least three alternating currents having phase displacements in relation to one another; target current setting means for setting a first target current value and a second target current value, the second target current value being determined on the basis of at least the steering torque signal; motor current detecting means for detecting motor current values supplied to the brushless motor and generating motor current signals corresponding to the detected motor current values; an AC/DC converter for converting the motor current signals into a first detection current signal and a second detection current signal, the motor current signals being indicative of the at least three alternating current values with phase displacements, and the first and second detection current signals being indicative of direct current values; first deviation calculation means for calculating a deviation of the direct current value represented by the first detection current signal from a the first target current value and producing a deviation signal indicative of the calculated deviation; second deviation calculation means for calculating a deviation of the direct current value represented by the second detection current signal from the second target current value and producing a deviation signal indicative of the calculated deviation; motor control means for controlling driving of the brushless motor through a control process on the basis of the deviation signals outputted from the first and second deviation calculation means; and attenuation means provided in a feedback transmission path of the second detection current signal for attenuating a high frequency noise mixed in the second detection current signal.