L. Liu

Effect of variation of B-H properties on loss and flux inside silicon steel lamination

The effect of the variation of B-H properties obtained by different means and data access modes under different exciting frequencies on iron loss and flux in GO silicon steel laminations is investigated, and the results of the numerical modeling is demonstrated on a benchmark model.

Measurements and Calculation of Core-Based

An efficient method for modeling the global magnetic properties of the transformer under dc-biased condition based on a laminated core model of product level is proposed. The magnetic property data of the core under dc-biased condition are obtained, such as the Bm-Hb curve and hysteresis loops, which can be used in the analysis of dc-biased field and electromagnetic design of products. The exciting currents of dc-biased laminated core model are calculated and validated with the measured ones.

B-H

In this paper, the effect of different excitation patterns on both the iron loss and flux inside solid magnetic steel plates and laminated silicon steel sheets is investigated. Some practical approaches to nonlinear and anisotropic eddy-current problems under 3-D excitation conditions are proposed, in which the usual measured loss data is not adequate within the penetration depth where the eddy currents are induced by fluxes normal to the lamination. The benchmark results based on member models of Problem 21 with new extensions are presented to validate the proposal and to observe the electromagnetic behavior of the magnetic steel under different excitation patterns. The extensions to the benchmark Problem 21 are helpful for further Testing Electromagnetic Analysis Method (TEAM) activities.

Curve and Magnetizing Current in DC-Biased Transformers

Two transformer-based laminated core models, which have the same material and joint type but different leg length, are established, and the joint influence region (JIR) of the core models is proposed to investigate the magnetic flux and iron loss at core joints. In this way the equivalent magnetic path length of the square core can be determined, and the iron loss generated at core joints can be separated from the total core loss. An efficient approach to simulate the iron loss and the flux distributions at core joints is implemented and validated, which can be used in the electromagnetic design of products.

Effect of Excitation Patterns on Both Iron Loss and Flux in Solid and Laminated Steel Configurations

The electromagnetic (EM) barrier, the magnetic (M) shunt and a combination of both are widely used in electrical devices in order to control stray fields and effectively reduce the power loss that may lead to hazardous local overheating. This paper focuses on the 3-D finite element modeling and validation of multishielding at power frequencies. The hybrid (M+EM) shielding behavior of the current magnetic shunt configuration is numerically and experimentally examined and is compared to other types. The leakage flux complementary-based measurement method of stray-field loss is also proposed and verified based on the benchmark shielding models.

Magnetic Flux and Iron Loss Modeling at Laminated Core Joints in Power Transformers

The extended modeling of the magnetic properties of grain oriented electrical steel is presented in this paper which is based on a set of standard and scaled-down Epstein frames and a proposed two-level weighted processing of Epstein data, including the mean magnetic path length, specific magnetization loss and exciting power. The effects of excitation frequency, strip angle, and ambient temperature on the results obtained from the Epstein frames are investigated. It is shown that using the proposed Epstein combination and the two-level weighted processing method is an efficient way of building a model for determining magnetic losses more realistically, hence, improving the value of Epstein strip measurement data.

3-D Finite Element Modeling and Validation of Power Frequency Multishielding Effect

The excitation conditions of electrical steel are generally sinusoidal but, with the advent power electronics in recent years, dc-biased excitation is sometimes experienced. In this paper, an efficient method for modeling the global magnetic properties of the silicon steel under dc-biased condition was proposed. The measurement was carried out based on a laminated core model of product level which was designed and made by the authors. However, the DC bias magnetic flux can not be measured directly in the experiment, and then a simulated method was presented to calculate the dc magnetic flux in the iron core. The calculation program was developed based on MATLAB, thus the hysteresis loops of the iron core under biasing magnetization were obtained. In addition, the experimental study on the iron loss of silicon steel was carried out. The different iron loss curves under various dc-biased magnetic field strength were determined. They are necessary for the analysis of dc bias magnetic field and electromagnetic design of products.

Modeling of Magnetic Properties of GO Electrical Steel Based on Epstein Combination and Loss Data Weighted Processing

The effect of the B-H and Bm-Wt curves under different dc-biased magnetization on iron loss and flux in Si-Fe lamination obtained by a laminated core model is investigated, which has been demonstrated via the numerical modeling results based on model.