Abstract:The main purpose of this paper is the analytical study of self-shrinker solutions of the one-dimensional Landau-Lifshitz-Gilbert equation (LLG), a model describing the dynamics for the spin in ferromagnetic materials. We show that there is a unique smooth family of backward self-similar solutions to the LLG equation, up to symmetries, and we establish their asymptotics. Moreover, we obtain that in the presence of damping, the trajectories of the self-similar profiles converge to great circles on the sphere S 2… Show more
“…It is worth mentioning that the well-known Landau-Lifshitz-Gilbert (LLG) equation can be used to describe the hysteresis phenomenon with a simplified micromagnetic model that can be combined with a magnetic circuit simulation [24], yet it requires a relatively long computation time. Reference [25] points out that some solutions to the LLG equation can be explicitly expressed with confluent hypergeometric functions, which are also included in the present model.…”
Accurate hysteresis models are necessary for modeling of magnetic components of devices such as transformers and motors. This study presents a hysteresis model with a convenient analytical form, based on hypergeometric functions with one free parameter, built upon a class of parameterized curves. The aim of this work is to explore suitability of the presented model for describing major and minor loops, as well as to demonstrate improved agreement between experimental and modeled hysteresis loops. The procedure for generating first order reversal curves is also discussed. The added parameter, introduced into the model, controls the shape of the model curve, especially near saturation. It can be adjusted to provide better agreement between measured and model curves. The model parameters are nonlinearly dependent; therefore, they are determined in a nonlinear curve fitting procedure. The choice of the initial approximation and a suitable set of constraints for the optimization procedure are discussed. The inverse of the model function, required to generate first order reversal curves, cannot be obtained in analytical form. The procedure to calculate the inverse numerically is presented. Performance of the model is demonstrated and verified on experimental data obtained from measurements on construction steel sheets and grain-oriented electrical steel samples.
“…It is worth mentioning that the well-known Landau-Lifshitz-Gilbert (LLG) equation can be used to describe the hysteresis phenomenon with a simplified micromagnetic model that can be combined with a magnetic circuit simulation [24], yet it requires a relatively long computation time. Reference [25] points out that some solutions to the LLG equation can be explicitly expressed with confluent hypergeometric functions, which are also included in the present model.…”
Accurate hysteresis models are necessary for modeling of magnetic components of devices such as transformers and motors. This study presents a hysteresis model with a convenient analytical form, based on hypergeometric functions with one free parameter, built upon a class of parameterized curves. The aim of this work is to explore suitability of the presented model for describing major and minor loops, as well as to demonstrate improved agreement between experimental and modeled hysteresis loops. The procedure for generating first order reversal curves is also discussed. The added parameter, introduced into the model, controls the shape of the model curve, especially near saturation. It can be adjusted to provide better agreement between measured and model curves. The model parameters are nonlinearly dependent; therefore, they are determined in a nonlinear curve fitting procedure. The choice of the initial approximation and a suitable set of constraints for the optimization procedure are discussed. The inverse of the model function, required to generate first order reversal curves, cannot be obtained in analytical form. The procedure to calculate the inverse numerically is presented. Performance of the model is demonstrated and verified on experimental data obtained from measurements on construction steel sheets and grain-oriented electrical steel samples.
A new model of hysteresis based on hypergeometric functions is presented. The model is based on a class of parameterized functions with two free parameters, which contains the Takács model as a special case. With a suitable choice of the parameters, a model of hysteresis can be constructed, which shows improved conformance to experimental data, such as steep and narrow loops obtained from grain-oriented electric steel. The performance of our model was tested and verified on our measurement data, as well as data from other sources. It retains the advantages such as simple numerical implementation and parameter estimation while offering an increase in accuracy.
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