Alternative Diagnostic Approaches for Various Single-Fault Conditions in Direct-Drive Low-Speed Coreless Permanent Magnet Generators

A finite-element model of the direct-drive coreless permanent-magnet generator is used to simulate faults individually. Each fault case—rotor magnet demagnetization, a stator inter-turn short circuit, static eccentricity, and dynamic eccentricity—is introduced into the finite-element analysis (FEA) model separately, rather than in combination. For each isolated fault scenario, the stator current signals are processed using the Extended Park’s Vector Approach (EPVA) and the electromagnetic torque is examined in the frequency domain. The EPVA spectra and torque harmonics exhibit unique features for each fault type, allowing for clear discrimination among faults. These results demonstrate that modeling and analyzing faults one at a time yields distinct diagnostic signatures.