APPARATUS AND METHOD FOR CONTROLLING AN ELECTRIC ASSIST STEERING SYSTEM

摘要

An electric assist steering system (10) includes a torque sensor (16) that provides an applied torque signal (24) indicative of applied steering torque. A motor position sensor (36) provides a motor position signal (40) indicative of the relative position between the rotor and the stator of an AC permanent magnet electric assist motor (22). A first controller (26) controls energization of the electric assist motor and a second controller (54) calculates a DQ vector value in response to applied steering torque and motor position. The second controller (54) also transforms the monitored motor current and position into DQ values. The second controller (54) compares the DQ values responsive to applied steering torque with the DQ value from monitored motor current and position. The electric assist motor (22) is disabled if the comparison indicates inconsistent results.