RELAY CONTACT FAILURE DETECTOR IN ELECTRIC MOTOR DRIVE STEERING AUXILIARY MECHANISM

摘要

PROBLEM TO BE SOLVED: To provide a relay contact failure detector in an electric motor drive steering auxiliary mechanism capable of preventing the uncontrolled steering without breaking a switching transistor by a large current when a relay contact failure is detected while suppressing the increase in the cost. SOLUTION: Second capacitors C1 and C2 having a capacity smaller than that of a first capacitor C0 provided on a line for connecting a relay R to an electric motor M are provided between the switching transistors FET H1 and FET H2 on the drive power source side in a bridge circuit and switching transistors FET L1 and FET L2 on the ground side. Discharging is implemented step by step via the second capacitors C1 and C2 by alternately turning ON/ turning OFF the switching transistors FET H1 and FET H2 on the power source side and the switching transistors FET L1 and FET L2 on the ground side.