Modified Preisach Model of Hysteresis in Multi Air Gap Ferrite Core Medium Frequency Transformer

Abstract

This article presents the modified Preisach model of hysteresis for a 3-phase medium frequency transformer in a 100 kW dual active bridge converter. The transformer magnetic core is assembled out of ferrite I-cores, which results in multiple parasitic air gaps. For this transformer, the hysteresis loops were measured and the parameters of the Preisach model were determined. The Preisach distribution function is approximated with a two-dimensional Gauss function series and the feedback function is a 3rd-degree polynomial. The optimized identification of Preisach distribution function parameters was prepared. Two sets of parameters were determined based on the analysis of major and minor hysteresis loop. The developed model is used to analyze the transformer core power loss. A new set of Steinmetz equation parameters for the multi air gap ferrite core MFT is proposed.

A Higher-Order Loss-Separation Model for Fast Estimation of Core Loss in High-Frequency Transformers

“…When the magnetic induction strength and frequency are determined, the hysteresis loss is not much related to the waveform, the main influence on the accuracy of the calculation is eddy current loss and residual loss. Barbiso derived the two parts of the original calculation formula as ( 6) and (7)based on the loss separation model: where 𝜎 is the material conductivity, 𝑑 is the core stack thickness, 𝑆 is the core cross-sectional area, 𝜌 is the material density, ' T is the magnetization period ,and 𝐺 is the dimensionless factor.…”

“…The hysteresis modeling method focuses on the magnetization mechanism of ferromagnetic materials [5], including purely mathematical models such as the Preisach model and physical models such as the Jiles-Atherton model. Reference [6] incorporated nonlinear core behavior into the finite element formulation using a vector hysteresis model with a magnetic difference tensor, and proposed a finite element model for analyzing the iron loss of threephase transformers; Research in [7] developed an improved Preisach model for three-phase mediumfrequency transformers. They analyzed the transformer core power losses by optimally identifying the parameters of the distribution function of the Preisach hysteresis model.…”