Steering system and method for controlling the same

1. A steering system, comprising:

an EPS steering motor connected to a first inverter and a second inverter;

an additional motor connected to the first inverter and the second inverter and providing a steering-related additional function;

a main ECU including the first inverter and controlling the EPS steering motor and the additional motor through the first inverter; and

a sub ECU including the second inverter and controlling the EPS steering motor and the additional motor through the second inverter,

wherein the EPS steering motor alone or the additional motor alone is controlled according to a preset condition.

2. The steering system of claim 1 , wherein the preset condition is set to control the EPS steering motor alone or the additional motor alone based on at least one of vehicle driving state information or additional motor type information.

3. The steering system of claim 2 , wherein the preset condition is set to;

stop controlling the additional motor if it is determined that a vehicle is in a driving state based on the vehicle driving state information, and

allow control of the additional motor if it is determined that the vehicle is in a stopped state.

4. The steering system of claim 2 , wherein both the main ECU and the sub ECU are configured to control simultaneously a steering wheel when the vehicle is in a driving state based on the vehicle driving state information.

5. The steering system of claim 4 , wherein the EPS steering motor is configured to provide a portion of an output by the main ECU and a remaining portion of the output by the sub ECU when the EPS steering motor is controlled.

6. The steering system of claim 3 , wherein the additional motor is a tilt motor for a steering wheel or a telescopic motor for the steering wheel.

7. The steering system of claim 2 , wherein the preset condition is set further considering state information for the main ECU and the sub ECU, and wherein the preset condition is set to stop controlling the additional motor if it is determined that at least one of the main ECU or the sub ECU is in an abnormal state.

8. The steering system of claim 2 , wherein the preset condition is set to allow control of the additional motor if the additional motor is a steering wheel hide motor according to the additional motor type information, and when a driving speed of a vehicle is a preset speed or less, and the vehicle drives straight.

9. The steering system of claim 1 , wherein three additional motors are connected and controlled by the main ECU and the sub ECU.

10. The steering system of claim 1 , wherein the EPS steering motor is a dual winding motor having two windings, and each winding of the EPS steering motor is controlled by the main ECU and the sub ECU, respectively.

11. The steering system of claim 2 , wherein the additional motor is at least one of a tilt motor, a telescopic motor or a steering wheel hide motor,

wherein different conditions are set depending on whether a control input signal is for the tilt motor, the telescopic motor, or the steering wheel hide motor.

12. The steering system of claim 2 , wherein, if the vehicle is in a driving state based on the vehicle driving state information, the preset condition is set to disregard a control input signal for the additional motor even if the control input signal for the additional motor is input.

13. The steering system of claim 2 , wherein if one of the main ECU and the sub ECU is in an abnormal state and the other one of the main ECU and the sub ECU is in a normal state, the EPS steering motor is controlled by the other one of the main ECU and the sub ECU, which is in the normal state.

14. The steering system of claim 2 , wherein a control input signal is for a steering wheel hide motor,

wherein the preset condition is set to preferentially perform a control on the steering wheel hide motor under a specific condition if it is determined that either the main ECU or the sub ECU is in an abnormal state.

15. The steering system of claim 14 , wherein the specific condition includes a condition whether the vehicle speed is a predetermined speed or less and the vehicle drives straight.