Model-based fault diagnosis of DC motors of stamping processes

An automatic fault diagnosis system for stamping presses is presented in this work. The final application pretends to offer complete information about the state of the presses und prevent from possible faults while they are still incipient. The developed application diagnoses mechanical faults in the gear system and electric and mechanical faults in the DC motor. This paper is focused on the diagnosis of the dc motor. Parity equations from input-output model have been used to obtain a residual generator that allows detecting failures in the motors. These residuals allow detecting and diagnosing different faults of the DC motor. In this case five residuals have been designed to detect faults in the excitation and armature circuits (lost of isolation and voltage Iosses in the brushes), in the sensors (current and speed) and in the thiristors of the controller.