The effect of hydrostatic stress on magnetic properties of Mn-Zn power ferrites at varying excitation levels

Abstract

In this paper, the effects of hydrostatic stress on the magnetic properties of Mn-Zn power ferrites are discussed. Ring cores were embedded in cement and the curing process gradually exerted pressure on the core. A novel testing method was developed to continuously measure the power losses and the magnetic susceptibility in dependence on magnetic excitation at a fixed frequency and room temperature with a vector network analyzer. After 450 h, a maximum compressive stress of 120 MPa was reached. Power loss up to 300% was observed, while magnetic susceptibility dropped by 35%. The magneto-mechanical effect on core losses was simulated with the Hodgdon-Esguerra hysteresis model, showing excellent agreement with tested results, which allows us to predict the behavior of ferrite tiles embedded in load-bearing surfaces for wireless power transfer (WPT) applications.