Patent ID: 11817281

Abstract:
A method of detecting welded contacts in a relay. The method includes performing, at a first point in time, the applying of a drive to the activation coil to conduct a coil current through the activation coil, the coil current increasing to a first current level, the first current level being less than a pull-in current of the relay; responsive to the coil current reaching the first current level, turning off the drive to the activation coil to discharge the coil current at a first clamping voltage; and measuring a first discharge time corresponding to a first inductance from the turning off of the drive to the activation coil to the coil current reaching a second current level, the second current level being less than the first current level. These operations are repeated at a second point in time to obtain a second inductance. Comparison of the first inductance and second inductance determines whether a difference between the first and second inductances exceeds a comparison criterion.