Nsk Corporation

Nsk Steering Systems Co., Ltd.

Yusuke Itakura

Hideaki Kawada

Shuji Endo

Hideyuki Kobayashi

Yasuhiko Miyaura

Hisayoshi Koiwai

Toru Sakaguchi

Yuho Aoki

Kazuhiro Kumaido

Nobuhiro Kubo

Kei Chin

The present invention provides a controller of an electric power steering device which does not apply an uncomfortable feeling to a operation of steering wheel while securing a fault determination confirming period enough long to prevent an erroneous detection of a torque sensor fault, and can secure a safety operation of steering wheel, even in the case that an output value of a torque sensor detecting a steering torque of a steering wheel becomes abnormal.

Controller for electric power steering device

An object of the present invention is to provide an electric power steering apparatus which can continue control even if some of current detectors that detect phase currents of a three-phase motor break down. Phase currents of the failure current detectors are calculated by using detected signals from the normal current detectors, and the electric power steering apparatus can be continued to be controlled by using the current values.

Electric power steering apparatus

To provide a controller for an electric power steering system capable of balancing a steering assist force by correcting an offset and improving the steering feeling. A controller for an electric power steering system having motor driving means for driving a motor for electric power steering and motor current detecting means for detecting a current running through the motor is used in which the motor-driving means realizes a motor stop state in which no current runs through the motor under a non-energized state, uses a motor current detection signal under the motor stop state as the offset value of the motor current detecting means, and automatically corrects the offset of the motor current detecting means in accordance with the offset value.

Controller for electric power steering system

An electric power steering device enabled to surely detect a fault of its motor current detector circuit by avoiding the disturbance by an electrically insulated oxide film formed on the contact surface between the commutator and the brush of the motor. An ignition key is turned on, then the motor applied voltage is increased with time to break the oxide film so that the motor current flows normally. The estimated motor current is then compared with the detected motor current. When the absolute value of the difference between those estimated motor current and detected motor currents is over a predetermined limit value, it is determined that the motor current detection circuit is defective. It is also possible to break the oxide film by integrating each difference between the motor current command value and the detected motor current value, thereby increasing the current control value step by step and increase voltage applied to the motor.

Electric power steering device

A control apparatus of power steering device having functions of monitoring intermediate troubles such as offset or drift out of signal troubles of torque sensor, and limiting the current for limiting the assist function is presented. In a control apparatus of power steering device for controlling a motor on the basis of a current control value calculated from a steering assist command value calculated by calculating means on the basis of a steering torque generated on a steering shaft, and a current value of a motor for applying a steering assist force to a steering mechanism, wherein the difference of a main torque signal and a sub torque signal of a torque sensor for detecting the steering torque is stored preliminarily, and the difference of the main torque signal and the sub torque signal during operation is compared with the stored value, and at least the current control value is limited when the difference based on the comparison is a condition larger than a first prescribed value and continues for a time longer than a first prescribed time.

Control apparatus of power steering device

There is provided a control unit for an electric power steering apparatus that controls a motor for giving steering assist force to a steering mechanism, based on a current control value calculated from a steering assist command value calculated based on the steering torque generated in the steering shaft, and a current value of the motor. The control unit has a first controller and a second controller for controlling the motor. Based on a current command value calculated by the second controller, the second controller monitors the first controller that controls the driving of the motor based on the steering assist command value calculated by the first controller. When the first controller is in a status not controlling the steering assist command value, the function of the second controller for monitoring the first controller is limited.

Control unit for electric power steering apparatus

To provide a controller of an electric power-steering system, capable of improving the steering performance by presuming a motor angular speed .omega. in a range in which the angular speed of a motor is small and moreover very accurately presuming the motor angular speed and thereby, completely showing the functions for compensating the inertia of the motor and controlling the astringency of a vehicle. Because the presumed error of a back electromotive force between a model motor and a motor to be actually mounted is proportional to a motor current, a dead zone of a motor angular speed having a width proportional to a motor current is set to the presumed value of the motor angular speed. When the motor current is small, the width of the dead zone also decreases. Therefore, it is possible to presume an angular speed .omega. even in a region where the motor angular speed is small. Moreover, a motor angular speed is presumed by defining impedance models of motor driving systems in an intermittent mode and a continuous mode.

Controller of electric power-steering system

A control apparatus for an electric power steering system assures stability of the feedback control and control generation of noise from the control circuit when the steering wheel automatically returns to the neutral position by means of the self-aligning torque in order to improve the feeling of the steering operation. In the motor driving circuit connecting four semiconductor elements in the shape of H bridge, the semiconductors of the first arm are driven by the duty ratio D1 while the semiconductors of the second arm are driven by the duty radio D2 defined by the function of the duty ratio D1 (D2 is longer in time than D1).

Growing community of inventors

Gunma, Japan

Yusuke Itakura