Shumpei Ito

Macroscopic magnetization modeling of silicon steel sheets using an assembly of six-domain particles

A simplified domain structure model having six domains is proposed for mesoscopic magnetization under cubic anisotropy. The six-domain model represents 90° and 180° domain-wall motions by the volume-ratio variations of domains. The magnetization process of grain-oriented and non-oriented silicon steel sheets is represented by the assembly of six-domain models. Simulated magnetization curves agree well with measured properties, and the effect of compressive stress is successfully reconstructed.

Equivalent Circuit Modeling of DC and AC Ferrite Magnetic Properties Using H-Input and B-Input Play Models

An equivalent circuit model is proposed to represent ferrite magnetic properties under ac and dc fields phenomenologically, where the H-input and B-input play models are used to handle hysteretic property accurately and concisely. A slow magnetization component is extracted from measured ac and dc properties. Frequency dependence of the ac loss is represented by an equivalent resistance. The simulated ac and dc magnetic properties agree with the measured properties.

The domain structure model including pinning effect based on the statistical distribution function

The assembled domain structure model (ADSM) taking account of the distribution of pinning sites is proposed. To apply to the ADSM, the mesoscopic pinning field is formulated from the microscopic distribution. The magnetization curves and magnetization processes of the silicon steel sheet are simulated by the proposed model.

Finite element analysis of a ferrite-core inductor with direct current bias current using an equivalent-circuit model of dynamic hysteretic properties

The finite element (FE) modeling of a ferrite-core device is discussed. Measured properties of Ni-Zn ferrite ring cores show that even though the AC ferrite property is similar to that caused by the eddy-current field, the FE eddy-current analysis using an equivalent electrical conductivity cannot, in practice, represent the AC property. An equivalent-circuit model which describes AC/DC ferrite properties is applied to FE magnetic field analysis of a ferrite-core inductor. The simulated AC property with/without DC bias agrees with the measured one.

Simulation of the stress dependence of hysteresis loss using an energy-based domain model

The assembled domain structure model (ADSM) is a multiscale magnetization model that can be used to simulate the magnetic properties of a core material. This paper reveals the mechanism of the hysteresis loss increase due to compressive stress applied to a silicon steel sheet by conducting a simulation using the ADSM. A simple method of adjusting the simulated hysteresis loss to the measured loss is also proposed. By adjusting the hysteresis loss under a stress-free condition, the stress dependence of the hysteresis loss of a non-oriented silicon steel sheet is quantitatively reconstructed using the ADSM, where the stress-induced anisotropy strengthens the pinning effect along the stress direction.

Partially Implicit Method for Fast Magnetization Analysis Using Assembled Domain Structure Model

A partially implicit solution method is developed for fast magnetization analysis using an assembled-domain-structure model. The implicit time-marching scheme is simplified to avoid the inversion of a dense Jacobian matrix by separating the magnetostatic field into near and far components. The proposed approach achieves a reduction of computation time by 94%–99%.

Representation of macroscopic magnetization based on bifurcation property of domain structure

This study presents an efficient representation of macroscopic magnetization process based on the bifurcation property of mesoscopic two-domain magnetic particles. The macroscopic magnetization model, called the assembled domain structure model (ADSM), is constructed by assembling mesoscopic particles. Bifurcation is discussed of the two-domain state from the single-domain state in the unit mesoscopic particle in the ADSM. Based on this state bifurcation, a procedure to switch the macroscopic magnetization-state transition in the ADSM is developed, which dramatically reduces computation times in macroscopic magnetization simulations.

Efficient multiscale magnetic-domain analysis of iron-core material under mechanical stress

For an efficient analysis of magnetization, a partial-implicit solution method is improved using an assembled domain structure model with six-domain mesoscopic particles exhibiting pinning-type hysteresis. The quantitative analysis of non-oriented silicon steel succeeds in predicting the stress dependence of hysteresis loss with computation times greatly reduced by using the improved partial-implicit method. The effect of cell division along the thickness direction is also evaluated.

Postcorrection of Current/Voltage and Electromagnetic Force for Efficient Hysteretic Magnetic Field Analysis

Two postprocessing methods for correcting current or voltage are proposed for a more efficient hysteretic magnetic-field analysis. One method uses the instantaneous power difference, whereas the other derives an equivalent resistance to the hysteretic effect. The former method gives a good postcorrection of current for a voltage source. A postcorrection method for electromagnetic force is also discussed, and is demonstrated to give a good approximation of this force.

Method for current/voltage post-correction for efficient hysteretic magnetic field analysis

Two post-processing methods of correcting the current-voltage property are proposed for the efficient hysteretic magnetic field analysis. One uses the instantaneous power difference by the post-processing method. The other gives an equivalent resistance to the hysteresis effect. The analysis of the drum-type ferrite-core inductor using the former method agrees with the finite element magnetic field analysis that directly handles the hysteretic property.