ELECTRIC POWER STEERING SYSTEM AND CONTROLLER OF THE ELECTRIC POWER STEERING SYSTEM

摘要

Electric power steering system has steering mechanism; input and output shaft side rotation angle sensors detecting rotation angles of input and output shafts; operation circuit calculating command current for an electric motor; rotation direction judging circuit judging whether rotation directions of the input and output shafts are identical; advanced-phase judging circuit judging which phase of input and output shaft side rotation angle signals (S1, S2) is advanced; normal/reverse input judging circuit judging that (i) when both rotation directions are identical and S1 is advanced, input is normal input and (ii) when both rotation directions are identical and S2 is advanced, input is reverse input; and command current correcting circuit. The command current correcting circuit corrects the command current so that when the normal input is judged, torque in the same direction as input shaft rotation direction generated by the electric motor is greater than a case of reverse input judgment.