On the Effect of Permanent Magnet Eddy Currents During Dynamic Short-Circuits in Traction Motors

Abstract

This paper studies the impact of permanent magnet eddy currents on three-phase short-circuit behavior in traction motors. A semi-analytical method is presented, allowing for an evaluation of the sub-transient short circuit behavior resulting from eddy currents. Furthermore, based on typical parameters of traction motors, a fast assessment of the relevance of eddy currents in dynamic short-circuit scenarios is presented. Overall, the effect of eddy current field reaction is found to be small, if not negligible, but it tends to become relevant for larger machines without magnet segmentation. The presented findings are intended to act as a guideline for fast assessment of PM eddy current impact during fault of traction motors.