Conference Agenda

In this paper, an impact analysis of current harmonics on the electromagnetic noise of an interior permanent magnet synchronous motor is presented from a coupled electromagnetic-mechanical analysis. First, the electromagnetic noise analysis of the sinusoidal and harmonic currents is compared to verify the influence of current harmonics, and it is carried out through the coupled electromagnetic-mechanical analysis. Second, noise experiment was performed using via harmonic currents, and the results were compared with the results of the coupled analysis. From a theoretical basis and a comparison of the coupled analysis results and noise test results, the validity of the coupled analysis is verified, and the effect of the current harmonics on the electromagnetic noise is analyzed.

Aortic dissection is a hazardous disease initiated by a tear, allowing blood to flow into the aortic wall. Due to the pulsatile pressure in the aorta, the aortic wall layers get separated, developing a false lumen while the true lumen remains the usual passageway of blood. Haemodynamics in the false lumen, such as blood flow disturbances, recirculation and low wall shear stress, may cause thrombus formation and growth in the false lumen. Furthermore, the electrical conductivity of blood alters with haemodynamic changes in the aorta. Since blood is much more conductive than other tissues in the body, such changes can be identified with non-invasive methods such as impedance cardiography (ICG). Therefore, monitoring thrombosis in the false lumen with ICG can be helpful in the medical management of patients under treatment. A 2D computational fluid dynamics (CFD) simulation has been set up to model thrombosis in the false lumen and its impact on the blood flow induced conductivity changes. The electrical conductivity changes of blood obtained from this 2D simulation have been assigned as material properties of the blood-filled aorta in a 3D finite element (FEM) electric simulation model to investigate the impact of such changes on the impedance measured from the body's surface. The results show that it is possible to track the thrombosis by monitoring impedance signals because of changes in the aortic region's electrical conductivity distribution.

In this paper we consider geometry optimization of a new multi-turn time-of-flight (TOF) mass analyzer capable to analyze ions with a very high mass resolution. To optimize the geometry of the considered device we used finite element technology for the potential distribution modeling together with the fourth-order time step integration procedure for the charged particle tracing. To ensure especially high accuracy of the electric field computation we applied a nested procedure of the potential derivatives evaluation. Different strategies for the ion trajectories optimization were compared to choose a robust and reliable numerical procedure.

Strongly coupled electromagnetic-mechanical problems are presently very relevant for academic research and industrial technology- and product development. Although the algorithm basis for such coupled simulations is rather extensive and available in numerous publications, verification of the obtained results is very difficult and relies mainly on expensive, tedious, and time-consuming measurements. The main reason for this is an evident deficiency of reference examples with analytical solutions in the available literature. To mitigate the problem, this paper defines a strongly coupled electromagnetic-mechanical problem and presents its analytical solution in detail. The obtained analytical solution was cross-validated by comparing it against an in-house developed multiphysics FEM solver and an excellent agreement between the two was found.

This paper presents a time-domain circuit model for speed-controlled squirrel-cage induction machines that provides electromagnetic forces to structural-mechanical representations of drivetrains of electrified vehicles. The model is parametrized by magnetostatic calculations and its results reflect the influence of saturation, slotting and distributed windings. While, due to its simple structure, the model is substantially faster than full time-stepping field calculations, its results are sufficiently accurate for a multiphysical simulation environment, as demonstrated in numerical examples.

In this work we analyze the heating of a transcranial magnetic stimulation equipment. We present a design of an electrical circuit that reduces the current flow through a single element and a coil geometry with concentric windings, lowering the maximum operating

temperature of the stimulation coil by up to 20 ° C.

With the development of rare-earth barium copper oxide (REBCO) wires and magnets, higher DC magnetic fields with smaller magnets have been generated than ever. It is desired that such high field HTS magnets are applied to practical use: magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR), and so on. In recent years, a DC 45.5-T generation was succeeded using a REBCO magnet (14.4 T) inside a normal-conducting magnet (31.1 T), as a world record. In a post-mortem, plastic deformations on the magnet due to an unexpectedly strong magnetic force was observed. As one cause of the strong magnetic force is a screening current, screening current simulation considering magnet deformation has not been performed so far.

Previously, we developed a screening current simulation utilizing a thin film approximation technique. In this paper, we have newly developed a screening current simulation coupling with an elastic deformation finite element analysis. The previous screening current simulation without consideration of magnet deformation overestimated a screening current. Through newly obtained simulation results, we confirmed that the magnet deformation properly reduces the screening current, as compared with the previous simulation ones.

The evaluation of electric insulation in electric power transformer is a nonlinear problem involving the thermoelectric coupling, which is consuming both in time and storage resources in numerical modeling. In this paper, a combined reduced-order model based on the proper orthogonal decomposition (POD) and the QR-factorization discrete empirical interpolation method (Q-DEIM) is proposed to decrease the dimension of large-scale transformer model. Firstly, the Galerkin FEM is utilized to analyze the electric field with the dependence of the conductivity to the temperature and the electric field. Based on the electric potentials on snapshot samples, the reduced equation based on POD is deduced. Next, Q-DEIM is utilized to reduce the order of the nonlinear matrix. Different from the traditional DEIM, the Q-DEIM can be implemented more straightly. Finally, a transformer model is taken as an example, and the order of nonlinear term is largely reduced, which improves obviously the computation efficiency.

The main components of the electromagnetic environment of UHVDC transmission lines are the total electric field and ion current density above the ground. In this paper, the total electric field and ion current density under the UHV DC transmission line are calculated based on the upwind FEM. The new iterative convergence control technology is adopted to ensure the stability and rapidity of the iterative convergence process. In this paper, the results of the ion flow field above the ground of the ±800 kV transmission line are compared with the traditional upwind FEM and the convergence control factor method to verify the correctness of the method. The research conclusions of this paper can improve the accuracy of calculation of total electric field and ion current density, and realize accurate calculation of electromagnetic environment under UHVDC transmission line.

As a vital component in the converter valve of Extra-high Voltage (EHV) DC transmission, the anodic saturable reactor is often affected by the effect of magnetic, thermal and stress field in actual operation, so the simulation under ideal circumstances cannot accurately evaluate the equipment performance of the reactor. In order to simulate the complex effect of magnetic and mechanical field, a coupled finite element model of the anodic saturable reactor core is established, which includes the anisotropy data of soft magnetic materials. Besides, the magnetic characteristics, vibration acceleration and sound pressure are measured at different positions of the inner and outer surfaces of the core. The experimental results prove that the proposed model is effective to reduce the noise of the anodic saturable reactor. This work is of great significance to structure design of the anodic saturable reactor and the reduction method of vibration and noise.

In this paper is presented a dynamic model of magnetic screw coupled to mechanical system (MS-MS). This model consists of an element with rotational and translational motion (magnetic screw), a system of mass-spring-damper (external elements) and a magnetic force. First, an introduction of Magnetic Lead Screws (MLS) is presented to motivate the work. Then, a problem formulation is carried out to present the dynamic equations of magnetic screw coupled to mechanical system. Also, a 2D field model of magnetic screw is presented to obtain a thrust force and flux distribution. Then, a discussion of the important factors for MS-MS and the advantage of developing a reliable dynamic model is presented.

In this paper, a model for converter transformer inter-tap fault and the corresponding calculation method were presented, in which the electromagnetic field and the external circuit were calculated simultaneously with a direct data exchange. Furthermore, a modified Cassie-Mayr model was used to simulate the arcing fault in the circuit domain. A typical converter transformer inter-tap fault in the ±800 kV ultra-high voltage direct current (UHVDC) system was simulated. Results indicated that, during an inter-tap fault, the short-circuit current reached 70.3 kA in magnitude and the flux distribution changed significantly with large radial component of leakage flux appearing near the shorted turns.

A neural metamodel for the magneto-thermal analysis of an induction heating device is proposed. The double non-linearity of magnetic permeability against field strength and temperature which characterizes the workpiece is captured by the model, while the use of a pretrained Convolutional Neural Network (CNN) based on a reduced number of finite-element analyses makes it possible to dramatically decrease the computational cost.

Magnetic Gears (MGs) have been proposed for motion transmission since years ’80s of last century. Their main characteristic is the torque transfer, in contactless way, between two coaxial permanent magnets rotors through the interaction with a set of ferromagnetic poles. From the kinematic point of view their working principle is similar to the one of planetary mechanical gearing and they can transmit torque with a constant gear ratio determined by the number of permanent magnet (PM) pole pairs and of modulating iron poles. A test bench for measuring magnetic gear performance has been devised, designed and realised. Magnetic gears have been equipped with sensors coils to monitor the magnetic flux inside the structure and to compare it with simulation predictions. Details about the test bench, its drives and controls and preliminary results obtained by tests are presented and discussed.