In this paper, we present a general review of the status of numerical modelling applied to the design of high temperature superconductor devices. The importance of this tool is emphasized at the beginning of the paper, followed by formal definitions of the notions of models, numerical methods and numerical models. The state-of-the-art models are listed, and the main limitations of existing numerical models are reported. Those limitations are shown to concern two aspects: on the one hand, the numerical performance (i.e. speed) of the methods themselves is not good enough yet; on the other hand, the availability of model file templates, material data and benchmark problems is clearly insufficient. Paths for improving those elements are indicated in the paper. Besides the technical aspects of the research to be further pursued, for instance in adaptive numerical methods, most recommendations command for an increased collective effort for sharing files, data, codes and their documentation.

https://iopscience.iop.org/article/10.1088/0953-2048/28/4/043002/pdf

Potential and limits of numerical modelling for supporting the development of HTS devices

Purpose – This paper aims to give a perspective about the variety of techniques which are available and are being further developed in the area of coupled field formulations, with selective bibliography and practical examples, to help postgraduate students, researchers and designers working in design or analysis of electrical machinery.Design/methodology/approach – This paper reviews the recent trends in coupled field formulations. The use of these formulations for designing and non‐destructive testing of electrical machinery is described, followed by their classifications, solutions and applications. Their advantages and shortcomings are discussed.Findings – The paper gives an overview of research, development and applications of coupled field formulations for electrical machinery based on more than 160 references. All landmark papers are classified. Practical engineering case studies are given which illustrate wide applicability of coupled field formulations.Research limitations/implications – Problems ...

Applications of coupled field formulations to electrical machinery

This paper deals with a mixed analytical and numerical method to study the electromagnetic and thermal behavior of a dry type transformer under nonlinear loads. First a three-dimensional finite element method (FEM) using a magnetic scalar potential formulation is applied to compute the magnetic field in the free and iron spaces. This nonlinear FEM calculation is then combined with a mixed analytical and numerical form of the electrical circuit equation to take into account the skin and proximity effects in the rectangular windings. Then a steady state thermal FEM using the previous resultant current densities allows to characterize the temperature distribution of the transformer with nonsinusoidal currents. Finally this coupling model is applied to a 10-kVA distribution transformer to validate the effectiveness of the proposed method.

3-D computation of transformers overheating under nonlinear loads

The approach of magnetic scalar potential T/sub 0//spl phi/-/spl phi/ is widely popular for solving magnetic problems coupled with electric circuits. However, cuts are required to preserve the Ampere's law for the case of ferromagnetic circuits with holes surrounded by coils. The manual definition of cuts might not be evident even for experimented finite-element (FE) users. This paper presents a new automatic cuts generation algorithm. First, we present a tool that allows determining if a ferromagnetic region has holes or not. If holes are found, the region is then inflated to get automatically needed cuts. The presented algorithm is also applicable to generate electric cuts in massive conductors.

https://hal.archives-ouvertes.fr/hal-00164216/document

Automatic cuts for magnetic scalar potential formulations

This paper presents a new computational method of magnetic field in the air created by the known current density distribution in coils or solid conductor. The method consists of decoupling three components of the vector field T0. The method is faster and requires less memory than the classical approach, used in the magnetostatic and magnetodynamic finite-element formulations

/pdf/a-new-three-dimensional-3-d-scalar-finite-element-method-to-138ozmkzmc.pdf

A New Three-Dimensional (3-D) Scalar Finite Element Method to Compute $T_0$

This paper presents the theory and the validation of a new finite-element formulation to realize the coupling between electrical circuits and multiply connected magnetic circuits, using a magnetic scalar potential as state variable. For this purpose, we used formulations in reduced magnetic scalar potential versus T/sub 0/ taking into account electrical circuits and a total magnetic scalar potential taking into account cuts.

D. Boudaud

Papers

Coupled problem computation of 3-D multiply connected magnetic circuits and electrical circuits