Electric power steering apparatus

摘要

There is provided an electric power steering apparatus capable of alleviating an impact force at the time of an end contact, while giving natural and smooth steering feeling to a driver without degrading the steering feeling. When steering angle (θs) is equal to or larger than a limit starting steering angle (θst), a voltage target value (Vt) of an electric motor (13) is limited, and an upper limit (current limiting value I_Lim) of a current command value (Iref) is set based on the limited voltage target value (Vt) and the motor rotation speed (N) by use of a motor output characteristic of the electric motor (13). Then, the electric motor (13) is driven and controlled based on a current command value (Iref_Lim) that has been limited with the current command value (I_Lim).

主权项

1. An electric power steering apparatus, comprising:
a steering torque detection unit configured to detect steering torque to be input to a steering mechanism; a current command value calculation unit configured to calculate a current command value based on at least the steering torque detected by the steering torque detection unit; an electric motor configured to generate steering assist torque to be given to a steering shaft of the steering mechanism; a motor control unit configured to drive and control the electric motor based on the current command value; a steering angle detection unit configured to detect a steering angle of a steering wheel; a voltage target value setting unit configured to set a voltage target value of the electric motor based on the steering angle detected by the steering angle detection unit; a motor rotation speed detection unit configured to detect a motor rotation speed of the electric motor; and a current limiting value setting unit configured to set a limiting value of the current command value calculated by the current command value calculation unit by using the voltage target value set by the voltage target value setting unit and the motor rotation speed detected by the motor rotation speed detection unit, based on a motor output characteristic of the electric motor, wherein the motor control unit is configured to drive and control the electric motor based on the current command value obtained by limiting the current command value calculated by the current command value calculation unit to the limiting value set by the current limiting value setting unit as an upper limit.