Electric power steering apparatus

An electric power steering apparatus that has a function, which switches between a manual steering control which drives a motor by a first motor current command value calculated based on at least a steering torque and an automatic steering control which drives said motor by a second motor current command value calculated at a steering angle control section so that an actual steering angle follows-up a target steering angle, comprising:

• a target steering angle correcting section that performs a calculation process for said steering torque depending on a steering state and a vehicle speed and outputs a target steering angle correction value, and
• a correction outputting section that corrects said target steering angle by using said target steering angle correction value and inputs a corrected correction target steering angle into said steering angle control section;
• wherein said target steering angle correcting section comprises:
• a phase compensating section that performs a phase lead compensation or a phase delay compensation to said steering torque based on said steering state;
• a dead band gain section that inputs a first compensation steering torque from said phase compensating section, has a dead band at a region which said first compensation steering torque is small, and outputs a second compensation steering torque which increases in a same direction as an increasing direction of said first compensation steering torque depending on said vehicle speed;
• and
• a limiter that limits an upper limit value and a lower limit value of said second compensation steering torque depending on said vehicle speed, and outputs said correction target steering angle.

An electric power steering apparatus that has a function, which switches between a manual steering control which drives a motor by a first motor current command value calculated based on at least a steering torque and an automatic steering control which drives said motor by a second motor current command value calculated at a steering angle control section so that an actual steering angle follows-up a target steering angle, comprising:

• a target steering angle correcting section that performs a calculation process for said steering torque depending on a steering state and a vehicle speed and outputs a target steering angle correction value;
• and
• a correction outputting section that corrects said target steering angle by using said target steering angle correction value and inputs a corrected correction target steering angle into said steering angle control section,
• wherein said target steering angle correcting section comprises:
• a dead band gain section that inputs said steering torque, has a dead band at a region which said steering torque is small, and outputs a first compensation steering torque which increases in a same direction as an increasing direction of said steering torque depending on said vehicle speed;
• a phase compensating section that performs a phase lead compensation or a phase delay compensation to said first compensation steering torque based on said steering state;
• and
• a limiter that limits an upper limit value and a lower limit value of a second compensation steering torque from said phase compensating section depending on said vehicle speed, and outputs said correction target steering angle.