Comparative Investigation of Three Diagnostic Methods Applied to Direct-Drive Permanent Magnet Machines Suffering from Demagnetization

Direct-drive permanent magnet machines are ideal candidates for remote renewable applications, due to their independence from gearboxes and minimization of maintenance needs. However, faults may still appear in the generator of such a machine and affect its operation and production. Not only can demagnetization cause a catastrophic breakdown if left unchecked, but it also directly impacts the output quality of generators. As such, demagnetization is a topic of great interest. This paper investigated the sensitivity of three diagnostic methods-current signature analysis (CSA), Park's vector approach (PVA), and extended Park's vector approach (EPVA)-for demagnetization fault detection on a coreless permanent magnet generator.