Control unit of electric power steering apparatus
A control unit of an electric power steering apparatus including a feedforward control section, that inputs input angle information and calculates a first compensation signal compensating the current command value, a feedback control section, that inputs output angle information and calculates a second compensation signal compensating the current command value, and a response control section that adjusts the current command value based on the first compensation signal and the second compensation signal.
1. A control unit of an electric power steering apparatus that drives a motor based on a current command value, and assists and controls a steering system, comprising:
an electronic control unit (ECU) configured to implement:
a feedforward control section that inputs a steering wheel angle and calculates a first compensation signal compensating said current command value;
a feedback control section that inputs a steering angle and calculates a second compensation signal compensating said current command value; and
a response control section that adjusts said current command value based on said first compensation signal and said second compensation signal;
wherein said feedback control section arranges a pole of a characteristic of a vibration mode where steering wheel inertia and motor inertia that constitute said electric power steering apparatus are relatively displaced in a steering stabilization frequency domain; and
wherein said response control section performs pole-and-zero cancellation so as to cancel said characteristic of said vibration mode.
2. The control unit of the electric power steering apparatus according to claim 1 ,
wherein said response control section inputs a difference between said first compensation signal and said second compensation signal.
3. The control unit of the electric power steering apparatus according to claim 1 ,
wherein a first response control section that inputs said first compensation signal and a second response control section that inputs said second compensation signal are comprised as said response control section; and
wherein a difference between an output of said first response control section and an output of said second response control section is used for adjustment of said current command value.
4. The control unit of the electric power steering apparatus according to claim 3 ,
wherein said feedback control section performs pole arrangement with respect to said characteristic of said vibration mode by raising a resonance ratio of a two-inertia system consisting of said steering wheel inertia and said motor inertia.
5. The control unit of the electric power steering apparatus according to claim 3 ,
wherein said feedback control section provides said pole with damping by a phase advance characteristic.
6. The control unit of the electric power steering apparatus according to claim 3 ,
wherein a damping factor of said characteristic of said vibration mode becomes more than or equal to a predetermined value by said pole-and-zero cancellation performed by said response control section.
7. The control unit of the electric power steering apparatus according to claim 3 ,
wherein said feedforward control section enables stability and responsiveness of said characteristic of said vibration mode at on-center to be set independently.
8. The control unit of the electric power steering apparatus according to claim 3 ,
wherein said control unit further comprises a phase compensation control section that performs phase compensation with respect to said current command value before said response control section adjusts said current command value.
9. The control unit of the electric power steering apparatus according to claim 1 ,
wherein said steering stabilization frequency domain ranges in about 20 Hz and over.
10. The control unit of the electric power steering apparatus according to claim 1 ,
wherein said feedback control section performs pole arrangement with respect to said characteristic of said vibration mode by raising a resonance ratio of a two-inertia system consisting of said steering wheel inertia and said motor inertia.
11. The control unit of the electric power steering apparatus according to claim 10 ,
wherein said resonance ratio is more than or equal to about 2.
12. The control unit of the electric power steering apparatus according to claim 1 ,
wherein said feedback control section provides said pole with damping by a phase advance characteristic.
13. The control unit of the electric power steering apparatus according to claim 1 ,
wherein a damping factor of said characteristic of said vibration mode becomes more than or equal to a predetermined value by said pole-and-zero cancellation performed by said response control section.
14. The control unit of the electric power steering apparatus according to claim 13 ,
wherein said predetermined value is about 0.6.
15. The control unit of the electric power steering apparatus according to claim 1 ,
wherein said feedforward control section enables stability and responsiveness of said characteristic of said vibration mode at on-center to be set independently.
16. The control unit of the electric power steering apparatus according to claim 15 ,
wherein said feedforward control section performs phase compensation.
17. The control unit of the electric power steering apparatus according to claim 1 ,
wherein said control unit further comprises a phase compensation control section that performs phase compensation with respect to said current command value before said response control section adjusts said current command value.