Demagnetization Fault Diagnosis of a PMSM Based on Structure Analysis of Motor Inductance

Abstract

A demagnetization fault in a permanent-magnet synchronous machine (PMSM) degrades performance and energy efficiency. The demagnetization fault causes flux-density difference and changes the PMSM inductances. Such varying parameters make it difficult to detect and diagnose the exact severity of a demagnetization fault. In this paper, we suggest a use of structural analysis of the PMSMs to diagnose the demagnetization fault. We can calculate varying inductances and consider the magnetic saturation effect with varying flux linkages of the machine. Combination of the proposed technique with the least-square (LS) method shows better results than the conventional methods in the estimation of flux linkages in the PMSMs with the demagnetization fault. Experimental results demonstrate that the proposed method works well both in the tracking of varying inductances and the diagnosis of the demagnetization fault.