Steering auxiliary motor control device in EPS system, and method thereof

1. A steering auxiliary motor control device comprising:

a receiver for receiving steering angle information and driver steering torque information from a sensor included in a vehicle;

a maximum steering angle determiner for determining a maximum steering angle of the vehicle based on the steering angle information and a preset reference steering angle information;

a limited motor torque determiner for determining a limited motor torque for limiting maximum motor torque outputted from a steering auxiliary motor based on at least one of a first condition including the steering angle information, maximum steering angle information and steering angle holding time information, or a second condition including the driver steering torque information, over-torque limit entry torque information, over-torque limit release torque information and steering torque holding time information;

a motor current controller for controlling the steering auxiliary motor by supplying current based on the limited motor torque determined by the limited motor torque determiner,

wherein

the limited motor torque determiner is configured to;

in response to the steering angle information coinciding with the maximum steering angle information for more than a preset first time, determine a first limited torque equal to or less than the maximum motor torque as the limited motor torque, and

in response to a driver steering torque of the driver steering torque information maintaining greater than an over-torque limit entry torque of the over-torque limit entry torque information for more than a second preset time of the steering torque holding time information, determine a second limited torque equal to or less than the maximum motor torque as the limited motor torque,

the motor current controller is configured to control, in response to the limited motor torque being determined, a control current value corresponding to the limited motor torque to be a maximum current value supplied to the steering auxiliary motor, and

the motor current controller is configured to:

in response to the first limited torque being set as the limited motor torque, reduce the maximum current value supplied to the steering auxiliary motor from a maximum motor torque current amount to a first limited torque current amount using a current limit slope, and

increase the maximum current value supplied to the steering auxiliary motor from the first limited torque current amount to the maximum motor torque current amount using a current limit release slope, the current limit release slope and the current limit slope being set differently.

2. The steering auxiliary motor control device of claim 1 , wherein the maximum steering angle determiner is configured to

compare the steering angle information with the preset reference steering angle information and update the preset reference steering angle information to the steering angle information in response to a value of the steering angle information exceeding a value of the preset reference steering angle information, and

set the updated reference steering angle information as the maximum steering angle information.

3. The steering auxiliary motor control device of claim 2 , wherein the reference steering angle information includes clockwise reference steering angle information in the case of rotating clockwise based on a zero steering angle and counterclockwise reference steering angle information in the case of rotating in a counterclockwise direction based on the zero steering angle, and

wherein the maximum steering angle determiner is configured to

distinguish between a case in which the steering angle information is input by being rotated clockwise based on the zero point steering angle and a case in which the steering angle information is input by being rotated counterclockwise, and

compare with a clockwise reference steering angle information and a counterclockwise reference steering angle information, respectively.

4. The steering auxiliary motor control device of claim 1 , wherein, the first limited torque is set to a value corresponding to a first ratio based on a value of the maximum motor torque as the limited motor torque.

5. The steering auxiliary motor control device of claim 1 , wherein, the second limited torque is set to a value corresponding to a second ratio based on a value of the maximum motor torque as the limited motor torque.

6. The steering auxiliary motor control device of claim 1 , wherein the maximum steering angle determiner further comprises:

a first limited torque determiner for determining the first limited torque as the limited motor torque based on the steering angle information and the maximum steering angle information; and

a second limited torque determiner for determining the second limited torque as the limited motor torque based on the driver steering torque information and the over-torque limit entry torque information, and

wherein, in response to conditions to which the first limit torque and the second limit torque are applied overlapping and being satisfied, the maximum steering angle determiner is configured to determine the limited motor torque based on each value of the first limited torque and the second limited torque.

7. The steering auxiliary motor control device of claim 6 , wherein the maximum steering angle determiner is configured to determine a smaller value of the first limited torque and the second limited torque as the limited motor torque.

8. The steering auxiliary motor control device of claim 6 , wherein the maximum steering angle determiner is configured to determine the limited motor torque based on a preset priority among the first limited torque and the second limited torque.

9. The steering auxiliary motor control device of claim 6 , wherein the maximum steering angle determiner is configured to

apply a preset weight to at least one of the first limited torque and the second limited torque, and

determine an average value of the values to which the preset weight has been applied as the limited motor torque.

10. A steering auxiliary motor control method comprising:

receiving steering angle information and driver steering torque information from a sensor included in a vehicle;

determining a maximum steering angle of the vehicle based on the steering angle information and a preset reference steering angle information; and

determining a limited motor torque for limiting maximum motor torque outputted from a steering auxiliary motor based on at least one of a first condition including the steering angle information, maximum steering angle information and steering angle holding time information, or a second condition including the driver steering torque information, over-torque limit entry torque information, over-torque limit release torque information and steering torque holding time information; and

controlling the steering auxiliary motor by supplying current based on the limited motor torque,

wherein

the determining of the limited motor torque includes:

in response to the steering angle information coinciding with the maximum steering angle information for more than a preset first time, determine a first limited torque equal to or less than the maximum motor torque as the limited motor torque,

in response to a driver steering torque included in the driver steering torque information maintaining greater than an over-torque limit entry torque included in the over-torque limit entry torque information for more than a second preset time included in the steering torque holding time information, determining a second limited torque equal to or less than the maximum motor torque as the limited motor torque, and

the controlling of the steering auxiliary motor includes: controlling, in response to the limited motor torque being determined, a control current value corresponding to the limited motor torque to be a maximum current value supplied to the steering auxiliary motor, and

the controlling of the steering auxiliary motor further includes:

in response to the first limited torque being set as the limited motor torque, reduce the maximum current value supplied to the steering auxiliary motor from a maximum motor torque current amount to a first limited torque current amount using a current limit slope, and

increase the maximum current value supplied to the steering auxiliary motor from the first limited torque current amount to the maximum motor torque current amount using a current limit release slope, the current limit release slope and the current limit slope being set differently.

11. The steering auxiliary motor control method of claim 10 , wherein the determining of the maximum steering angle comprises

comparing the steering angle information with the preset reference steering angle information, and updating the reference steering angle information to the steering angle information in response to a value of the steering angle information exceeding a value of the preset reference steering angle information, and

setting the updated reference steering angle information as the maximum steering angle information.

12. The steering auxiliary motor control method of claim 10 , wherein the first limited torque is set to a value corresponding to a first ratio based on a value of the maximum motor torque as the limited motor torque.

13. The steering auxiliary motor control method of claim 10 , wherein the second limited torque is set to a value corresponding to a second ratio based on a value of the maximum motor torque as the limited motor torque.

14. The steering auxiliary motor control method of claim 10 , wherein the current limit slope is set to reach a second limited torque current amount in a shorter time than the current limit release slope.

15. The steering auxiliary motor control device of claim 1 , wherein the current limit slope is set to reach a second limited torque current amount in a shorter time than the current limit release slope.