Irreversible demagnetization mechanism of permanent magnets during electromagnetic buffering

Radiation-Induced Demagnetization of Nd-Fe-B Permanent Magnets

Introduction The Advanced Photon Source (APS), as well as other third-generation synchrotron light sources, uses permanent magnets in the insertion devices to produce x-rays for scientific research [1,2]. When placed in a high-energy storage ring, these permanent magnets are subjected to irradiation from synchrotron radiation, high-energy bremsstrahlung, and bremsstrahlung-produced neutrons. Pr...

Method of making permanent magnets

Investigation of Permanent Magnet Demagnetization in Synchronous Machines during Multiple Short-Circuit Fault Conditions

Faults in electrical machines can vary in severity and affect different parts of the machine. This study focuses on various kinds of short-circuits on the terminal side of a generic 20 kW surface mounted permanent magnet synchronous generator and how successive faults affect the performance of the machine. The study was conducted with the commercially available finite element method software CO...

A Quasi-Static Electromagnetic Analysis for Experiments with Strong Permanent Magnets

An electromagnetic analysis is presented for experiments with strong permanent disc magnets. The analysis is based on the well known experiment that demonstrates the effect of circulating eddy currents by dropping a strong magnet through a vertically placed metal cylinder and observing how the magnet is slowly falling through the cylinder with a constant velocity. This experiment is quite spect...

Nonlinear Numerical Simulation of Permanent Magnets

Rare earth permanent magnet models are commonly used in the design of undulators and wigglers. Normally the operating point of the magnet in the B vs. H diagram corresponds to a linear reversible characteristic. The region of linearity is strongly dependent on the temperature. The operation of part of the magnet blocks in the region of non-linearity is responsible for the so-called irreversible...