Review of Magnetic Material Degradation Characteristics for the Design of Premagnetized Inductors

Premagnetization of inductors with a permanent magnet seems to be a constantly recurring subject for power magnetic designers. Perhaps because there is not much literature on this topic available, the common considerations about it focus on obvious problems of the use of permanent magnets in high-frequency magnetic fields. This paper discusses the main degradation mechanisms of permanent magnets in premagnetized inductors and how they can be calculated in applications. After a short introduction to magnetic materials this paper addresses the reliability concerns and discusses degradation effects and their calculations. The calculations of acceleration factors are shown, which are important for the calculation of the reliability based on mission profiles.