Nsk Corporation

Yasuhide Nomura

Toru Sakaguchi

Toshihiro Fukuda

Tamotsu Oumi

Kazuhiro Kumaido

Hirokazu Abe

Mitsuhiro Fukuda

An electric power steering apparatus that driving-controls a motor via inverters based on a current command value, and applies an assist force by the motor to a steering system, includes multi-system driving systems with the inverters for respective system-windings of the motor which is a multi-system motor, wherein respective multi-system current command value characteristics against a steering torque are applied so as to be disproportionate for left and right steering, to the respective multi-system driving systems, and an assist-control is performed in response to the individual current command value characteristics.

Electric power steering apparatus

A highly safe electric power steering device including a control device for determining the failure of a motor current detector based on the difference between the motor current estimate value and the detected motor current value is provided. The abnormality determining unit computes the absolute value of difference between the motor current estimate value and the detected motor current value, measures the number of times when the absolute value of difference exceeded the predetermined threshold value within the predetermined period, and measures further the cumulative value of the number of times of exceeding the threshold value within the predetermined period. When the cumulative value exceeded the predetermined reference number of times for determining abnormality, the motor current detector is determined to be abnormal.

Electric power steering device

An electric power steering device comprising a control unit capable of distinguishing a failure of a motor current detection device caused by a change in power voltage, an oxide film formed on the commutator of a motor or the contact point of a relay, etc. from a failure of the motor current detection device itself and judging a failure of the motor current detection device accurately. A motor current is sampled during which a predetermined constant voltage is supplied to the motor, and the detected motor current value is compared with a motor current estimated value to judge the failure of the motor current detection device.

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Maebashi, Japan

Yasuhide Nomura