Analysis and Diagnosis of Inter-Turn Short Circuit Faults in Dual Rotor Air-Cored PMSG - Series Connected Stator Coils

Inter-turn short circuit (ITSC) fault detection is a major challenge for direct-drive permanent magnet synchronous generators in renewable energy applications. In this paper, ITSC phenomena are investigated in a dual-rotor, air-cored Permanent Magnet Synchronous Generator (PMSG) with series-connected coils. An accurate finite element analysis model is developed and mathematically validated to characterize the electromagnetic performance under healthy and faulty conditions. In order to decipher the effect of ITSCs on the stator current distribution, contact resistance, and short-circuit ratio variations are investigated to derive the fault-induced current signatures. Typical conventional diagnostic methods like Motor Current Signature Analysis (MCSA) and Extended Park's Vector Approach (EPVA) are evaluated and found to be less sensitive on low-severity faults, which may lead to misdiagnosis. These findings suggest the need for complementary monitoring strategies towards the early fault detection for better operation reliability and efficiency of renewable energy systems.