| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an electric power steering device which uses a three-phase brushless motor for detecting an error such as a contact failure of a relay contact of a motor relay in a motor driver circuit. <P>SOLUTION: The electric power steering device forcibly excites an A-phase motor relay 42 and a B-phase motor relay 44, sets the duty ratio of a PWM signal for driving a switching element in the motor drive circuit as a specific duty ratio for an error diagnosis to detect an A-phase motor current, determines whether or not the absolute value of the A-phase motor current is equal to or larger than a predetermined threshold value, and determines whether a relay contact 42a of the A-phase motor relay and a relay contact 44a of the B-phase motor relay are normal or abnormal. When it is determined that the relay contacts are abnormal, the normal/abnormal determination process is repeated a predetermined number of times. When it is determined that the relay contacts are abnormal even after the several times of determining, the abnormal determination is settled, and a fail-safe process is performed. <P>COPYRIGHT: (C)2010,JPO&INPIT |
