FAILURE DIAGNOSTIC METHOD FOR MOTOR DRIVING CIRCUIT AND DEVICE THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a failure diagnostic device which can detect any failure without any supply of current and to accomplish reduction in weight and in a cost of this kind of device. SOLUTION: This failure diagnostic device is fitted in a reversibly rotatable motor driving circuit 1, in which a driving object motor M is connected to a valance position in a bridge circuit consisting of switching elements Q1-Q4. In this case, the switching elements Q1-Q4 constituting the bridge circuit are operated so that a given measurement condition is accomplished, and an electric potential of a predetermined one side terminal M+ of the driving object motor M is measured, and then, a failure position of the motor driving circuit 1 is determined on the basis of the measuring condition and the one side terminal electric potential measured in compliance with the measuring condition.