Apparatus and method for controlling steering of electric power steering system

A steering control apparatus of an electric power steering system for a vehicle, the apparatus comprising:

• a learning module configured to learn a learning end angle based on an end angle of an end of a rack bar based on a steering angle;
• an angular speed limit module configured to detect a target limit angular speed of the vehicle based on the learning end angle and the steering angle, detect an actual motor angular speed based on a steering angular speed, generate a limit current based on an error between the target limit angular speed and the actual motor angular speed, and limit the steering angular speed within the target limit angular speed;
• and
• a motor current generation module configured to generate a motor current for motor control based on the limit current and a command current received from a steering control module,
• wherein:
• the angular speed limit module comprises:
• a target limit angular speed detection unit configured to detect the target limit angular speed based on the learning end angle and the steering angle;
• a motor angular speed detection unit configured to detect the actual motor angular speed;
• and
• a limit current detection unit configured to generate the limit current based on the error between the target limit angular speed and the actual motor angular speed and adjust the limit current based on the actual motor angular speed;
• and
• the limit current detection unit comprises:
• an error detection unit configured to detect the error between the target limit angular speed and the actual motor angular speed;
• a limit current generation unit configured to generate the limit current by performing proportional integral (PI) control based on the error;
• a gain detection unit configured to detect a ramp-up/down gain corresponding to the actual motor angular speed;
• a limit current adjustment unit configured to adjust the limit current by applying the ramp-up/down gain to the limit current;
• and
• a limit current limit unit configured to limit the limit current within a presetting size.

A steering control method of an electric power steering (EPS) system, the method comprising:

• learning a learning end angle based on an end angle of an end of a rack bar based on a steering angle;
• detecting a target limit angular speed based on the learning end angle and the steering angle, detecting an actual motor angular speed based on a steering angular speed, generating a limit current based on an error between the target limit angular speed and the actual motor angular speed, and limiting the steering angular speed within the target limit angular speed;
• and
• generating a motor current for motor control based on the limit current and a command current received from a steering control module,
• wherein:
• the learning of the learning end angle comprises:
• determining whether a preset learning condition is satisfied;
• and
• accumulating and storing the end angle whenever a result of the determination indicates that the learning condition is satisfied and detecting the learning end angle based on the accumulated and stored end angles;
• and
• the determining of whether the learning condition is satisfied comprises:
• determining whether an over load protection (OLP) operation condition is satisfied based on column torque and the steering angular speed;
• and
• determining whether the steering angle exceeds a preset steering angle.