Conference Agenda

Magnetically Controlled Reactor (MCR) is widely used as reactive power compensation equipment owing to its favorable properties of smoothly adjusting its inductance value through DC bias. However, the DC bias makes the cores of MCRs saturated, resulting in high magnetostriction and vibration, especially at the corner and the T-joint of the MCR core. Because of the rotational magnetization at these areas, the electromagnetic vibration model of MCR must consider the vector hysteretic magnetostriction effect. Firstly, an improved magnetostriction model of silicon steel is proposed by combining the quadratic domain rotation model with the vector Jiles-Atherton hysteresis model. Then, based on the measured magnetization and magnetostrictive characteristics curves of silicon steel, the model's parameters are optimized by velocity controllable particle swarm optimization (VCPSO). Finally, the vector hysteretic magnetostriction model is combined with the finite element method(FEM) to simulate the vector vibration characteristics of MCR under DC bias. The simulation results show that the vector property of electromagnetic vibration and magnetic field at the T-joint area is higher than that at the corner area of the MCR core.

This article proposes a new method to include the vector hysteresis property of soft-magnetic materials in the hybrid analytical modeling (HAM). The HAM is advantageous compared to other mesh-based electromagnetic modeling techniques such as the finite element method (FEM) since it models the airgap analytically using Fourier analysis. In particular, this property decreases the number of degrees of freedom of the model and allows modeling the motion of the mover analytically without any change in the magnetic equivalent circuit (MEC). Unlike the air gap, the other regions including iron parts are modeled using MEC which allows calculating the local magnetic saturation in these regions. In this study, a vector hysteresis model is employed to take the local magnetic saturation into account instead of the single-valued magnetic saturation curve of the iron material. An anisotropic congruency-based vector hysteresis model is developed for the vector hysteresis calculation. The coupling between the HAM and the vector hysteresis model is achieved by the fixed-point algorithm. The algorithm uses the tangent lines on the vector hysteresis loops to define the remanent flux density and the permeability of the analyzed MEC element. The remanent flux density and the permeability are then used to calculate the reluctance and magnetic saturation related magneto-motive force source of the element. A variable flux reluctance machine (VFRM) with both dc- and ac-field windings in the stator is investigated using the developed model. The dc-biased sinusoidal magnetic flux density distribution in the iron material results in minor loops inside the major hysteresis loop. Hence, the vector hysteresis modeling is significant for the accurate calculation of both iron loss and developed torque of VFRMs.

This paper applies the reduced-order modeling approach considering radiation heat transfer for a comprehensive analysis of the thermal behavior of wireless power transfer systems for electric vehicles.

The analyses are done using finite element analysis modeling software ANSYS workbench. We could show that the achieved solution accuracy is sufficient and adequate.

Furthermore, experimental validations are carried out to further determine the consistency of the achieved reduced-order model with the testbed.

The multiscale finite element method has shown its high potential for the simulation of the eddy current problem in closed laminated cores. Compared to the standard finite element method, the multiscale finite element method dramatically reduces the requirements on the computational resources by using a coarse finite element mesh. This work presents the first step in the effort to extend the multiscale finite element method to magnetic circuits with air gaps. To this end, a two dimensional eddy current problem with the magnetic vector potential A and linear material relations has been studied for different configurations. Numerical results demonstrate the accuracy of the presented method.

This paper presents a 3-D analytical magnetic field analysis of an electro-magnetic eddy current coupling. Analytical magnetic distributions are predicted by employing a group of H-formulations in the conductor region and Laplacian equations with magnetic scalar potential in other regions in the Cartesian coordinate. Analytical results of magnetic field distributions and the electromagnetic force are derived and verified by the numerical computational by 3D finite element models in both Cartesian and cylindrical coordinate.

Large low-speed drives are designed multipolar, annular and magnetically saturated at rated operation. The electromagnetic computation with changing geometrical conditions therfore poses a cumbersome non-linear field problem due to its high amount of degrees of freedom. For an accurate predictive model of the machine acoustics and vibrations, the study of these topological impacts on the magnetic air gap field is indispensable. Particularly when considering an arbitrary air gap deformation, related to additonal spatial flux harmonics, the computational chain of the Finite Element Method (FEM) involves adaptions at each stage

(pre- and post-processing). The proposed modeling approach is universal and reduces the computational effort significantly by using FE-solutions of symmetrical machine parts with varying air gap width. 2D- and 3D-FE-simulations are performed to study the impact

of e.g. eccentricity, ovalization, flower-shaped deformations and rotor tilting. A method for the error estimation and the validitation is proposed. The results of the approach is compared to FE-solutions of a complete 2D-model and a partial 3D-model with an examplary

deformation. The aim of this work is to study both magnetic air gap fields and forces efficiently in an exemplary high-pole wind turbine generator with a deformed air gap topology by interpolating and assembling appropriatly single-pole solutions.

A transient model of an induction machine is developed in this work using an artificial neural network. The model is suitable to be used for direct-on-line and converter fed induction machines. Different inputs and model configurations are investigated to find an optimal solution in developing the transient model. Finite element based model of induction machine is used to generate the training and testing datasets. The transient model can be used to estimate the current and torque at any given time accurately in real time, which makes it suitable to use in digital twin services.

Sub model approaches for electromagnetic finite element analyses offer opportunities of efficiently analyzing smaller regions in high detail influenced by magnetic field arising over much larger domains. A novel sub model technique allowing transient analysis with non-linear materials in three-dimensional space is validated through comparisons with the results obtained by measurements and by employing conventional finite element approaches. As an example, an end zone of a turbogenerator is investigated by studying different open and short circuit conditions. Comparisons are carried out in time and frequency domains.

Determination of eddy current loss in conductors is of high relevance for the design of electrical machines. This article introduces, discusses, and benchmarks novel approaches to accelerate the calculation process of eddy current loss in Roebel-bars influenced by magnetic airgap and stray fields in a turbogenerator’s end-region. Methods can also be employed in other fields of application.

With the advent of the digital age, real-time monitoring, diagnose and control become an essential demand in life cycle management of electrical equipment. The methods for behavior modeling that allows accurate and real-time physical simulation gain increasing attention in recent years. This work proposes a methodology by using the model order reduction technique based on proper generalized decomposition to build a compact behavior model of an induction motor. The association of this behavior model with the mechanical rotation equation leads to a twin-model of the motor that can reflect its physical state in real time. Results show that the twin-model can provide accurate time-domain response of the motor (including the speed and the torque) as compare to the FEM simulation while dramatically reduces the simulation time.

Numerical simulation of magneto-quasistatic problems based on the Finite Element (FE) method can generate important computational time. Then, Model Order Reduction (MOR) approaches based on the Proper Orthogonal Decomposition (POD) allows reducing the

calculation time by projecting the FE model into a reduced basis.

A reduced basis constructed from simulation results may not be suited for the projection of the time derivative of the FE solution in the case of magnetoquasistatic problems. In this communication, methods are proposed to construct reduced bases, lowering the reduction error on the FE solution and its time derivative in the conductive domain, in the case of a non-linear magneto-quasistatic problem. The methods are applied to a squirrel-cage induction machine.

The calculation of steady-state load operating point to initialize transient finite element simulations of turbine generators using ”new” winding vectors and space phasor concept is discussed in this paper. Only non-linear magnetostatic solutions are required to found the steady-state initial condition. The formulation has been readily incorporated in a finite element software called FLD which is based on the modified nodal analysis framework to solve the circuit-field problem with a strong coupling. The availability of experimental data for steady-state as well as transient conditions for a 150 MVA turbine generator allows the validation of our proposal. The study highlights the advantages of incorporate the initial condition calculation in available FE software.

Using magnetic charge method has been proven to be effective in reducing the computational cost when modelling a permanent magnet and coil. Despite such effectiveness, magnetic charge modelling of an arbitrary-shaped coil was yet to be developed, and conventional modelling method is limited to rectangular coils. In this paper, we propose a new magnetic charge modelling method of an arbitrary-shaped coil.

In this paper, we propose an interactive visualization method for motor design. We have proposed a visualization system for education using AR and VR. As a further development of this, we are working on motor design as an industrial application. There are two issues in achieving high-speed interactivity. One is a fast mesh modification method in finite element analysis, and the other is a fast solving method. We propose a high-speed mesh modification method that utilizes regularly arranged grid points and coordinate transformation. In the proposed design system, the user can immediately observe the analysis result of the design change. Furthermore, if the proposed system is executed in cooperation with the projector, designers can change the design of the motor with their fingers and discuss it on the whiteboard.

The main contribution of this paper is the calculation of the zero sequence impedance of a real zig-zag transformer (9,959 kVA @ 60 seconds at 34.5 kV). Employing magnetic energy storage and using a 3-D finite element model, the behavior of the magnetic field is determined to calculate the zero sequence impedance. The results obtained were experimentally validated in the laboratory and present a percentage error of less than 2.0 %.