Modelling Demagnetized Permanent Magnet Synchronous Generators using Permeance Network Model with Variable Flux Sources

Abstract

The partial demagnetization in a four-pole 1.5 kW surface mounted permanent-magnet synchronous-generator was modeled by permeance network model (PNM). The results were compared to a 2-D time-stepping finite element analysis (FEA). Both models where simulated in scenarios where one of the magnets where 20 % and 100 % demagntized and when none of the magnets where demagnetised. The results showed that the proposed PNM with variable magnetic flux sources matched the results of the FEA. The proposed method only need to invers the permeance matrix once before the time simulation, while the traditinal PNM need to invers it in every time step. This make the proposed model less computationally heavy when modeling electrical machines in healthy and faulty conditions, like demagnetization, short circuit, and static eccentricity. The difference is smaller when modeling dynamic eccentricity, becuase the geometry of the airgap changes over time.