Analysis of Inter-turn Short Circuit Fault in Iron-core Permanent Magnet Linear Machine

Analyzing the primary inter-turn short circuit ring current in iron-core permanent magnet linear machines (PMLMs) is of significance to the inter-turn short circuit fault analysis. An equivalent armature circuit model combined magnetomotive force-permeance model is proposed to predict the inter-turn short circuit ring current. First, the magnetomotive forces produced by permanent magnets and armature current are multiplied with airgap permeance considering the slotting effect to acquire the airgap flux distribution. The flux linkage in the short circuit ring produced by permanent magnet and armature current is obtained respectively with the knowledge of flux distribution. Then, the flux linkage in the short circuit ring is calculated by vector synthesis method using the former two types of flux linkage. The effectiveness of the proposed method is validated by finite-element analysis (FEA). Furthermore, influences of various turns of short circuit rings and different places of inter-turn short circuit faults on the performance of the machine including shorted current, phase current and force characteristics are investigated based on FEA. Finally, a prototype is manufactured to validate the proposed method and FEA results experimentally. ©2023 Chin.Soc.for Elec.Eng.