Fault diagnosis on modern three-phase traction vehicles

Traction vehicles with high power and for high speeds are increasingly being supplied with three-phase drive systems, the majority of them are of the asynchronous type, in which the asynchronous motors are fed at variable frequency by self-commutated static converters. Control of the drives as well as the higher-order functions for the vehicle and, possibly, the train too, is performed by highly integrated microcomputer systems. Automated vehicles with variable-speed drives are very complex systems. Faults, especially in the region of the converter and process control, do not make themselves apparent by steadily increasing wear, and therefore cannot be predicted. Hence, on such vehicles the rapid determination of the cause of a fault is eminently important. The authors show how, in such cases, diagnostic facilities can render valuable help