Koyo Seiko Company, Ltd.

Honda Giken Kogyo Kabushiki Kaisha

Kazuyuki Yoshida

Mitsuhiko Nishimoto

Masataka Izawa

Hiroaki Kaji

Mitsunori Kawashima

Atsushi Igo

Nobuyuki Sasaguchi

Takahiro Aoki

An electric power steering system is provided which assists a steering operation by applying a driving force generated by an electric motor to a steering mechanism of a motor vehicle. The system includes a sensor (e.g., a torque sensor) for acquiring information necessary for controlling the electric motor, and a board provided adjacent the electric motor and having a sensor signal processing circuit for processing a signal from the sensor. A temperature sensor for acquiring temperature information necessary for controlling the electric motor is mounted on the board.

Electric power steering system

A control system for an electric power steering system which generates a steering assist force by an electric motor driven on the basis of a steering torque applied to an operation member. The control system includes: a target current determining circuit for generating a target current value according to the steering torque; a compensation value determining circuit for generating a compensation current value according to a time-based differential value of the steering torque; a waveform transforming circuit for performing a waveform transformation to convert the compensation current value into a modified compensation value which sinusoidally changes with time; a circuit for generating a control command value by superimposing the modified compensation value obtained through the waveform transformation on the target current value; and a motor driving circuit for driving the electric motor on the basis of the control command value.

Electric power steering control system

An electric power steering apparatus is disclosed in which steering return control is maintained when vehicle speed reaches a predetermined vehicle speed range after the vehicle speed has been lower than the speed range, and steering return control is disabled when the vehicle speed reaches the predetermined vehicle speed range after the vehicle speed has been higher than the speed range and steering angular velocity has been higher than a predetermined value. Therefore, the control state between the steering return control and convergence control can preferably be switched so that the steering wheel settles quickly to a steering angle predetermined point based on the vehicle speed and the steering angular velocity even while the steering state is not changing.

Electric power steering apparatus

An electric power steering apparatus comprising dead zone detecting device for detecting whether a detected value of a steering torque is no more than a predetermined value, that is, in a dead zone or not, steering angular velocity detecting device for detecting the rotation speed of a steering wheel, and motor braking device for braking a motor by short-circuiting the terminals of the motor by the PWM control corresponding to the rotation speed of the steering wheel detected by the steering angular velocity detecting device when the detected value of the steering torque is detected to lie in the dead zone.

In an electric power steering apparatus, it is judged whether or not a value of primary delay of temperature increase in a driving circuit for an electric motor tends to decrease, and when the value of primary delay is judged to tend to decrease, a new value of primary delay is obtained with a time constant set smaller, so that an upper limit value of a motor current can be decided on the basis of the new value of primary delay. Thus, a steering power can be rapidly recovered.

An electric power steering apparatus which quickly returns the steering wheel to the neutral position with a satisfactory steering feeling by switching a steering wheel return control for assisting the steering wheel return and a steering wheel convergence control for converging the steering wheel to the neutral position by braking a motor, according to the steering condition such as the rotational speed of the steering wheel is fast or slow when returning the steering wheel to the neutral position even when the vehicle speed is equal.

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Sakurai, Japan

Kazuyuki Yoshida