컬럼 타입 EPS의 토크 리플 저감을 위한 디지털 필터의 설계 기법에 대한 연구

The purpose of this paper is a technical methodology of a digital filter for reducing torque ripple in the Column type Electric Power Steering system (C-EPS). It is hard to handle all of the elements, which cause the problem of torque ripple, using only single notch filter, since C-EPS has unstable characteristics such as vibration and divergence. Moreover, the high value of damping ratio of the single notch filter is required in order to reduce the torque ripple. In order to compensate those disadvantages, a technical methodology of a torque ripple reduction digital filter is suggested based upon Kdac engineering study. The suggested digital filter is engineered by combining a LowPass Filter (LPF), HighPass Filter (HPF) and Notch Filter. The effectiveness of the suggested torque ripple reduction filter has been proven by comparative evaluation with single notch filter in the vehicle test.