International Journal of Applied Electromagnetics and Mechanics - Volume Pre-press, issue Pre-press

Authors: Witczak, Pawel | Osinski, Piotr

Article Type: Research Article

Abstract: The article discusses the impact of reactive power load on additional power losses in a high-power transformer operating at a VAr static compensation station. The presence of an almost pure capacitive load on the secondary side together with the thyristor switches is the cause of high-frequency components in the phase currents. The additional effect of electrical resonance between the transformer inductance and the load capacitance is also taken into account. The analysis is achieved using a three-dimensional finite element approach.

Keywords: Power transformer, capacitance load, eddy currents, power losses, finite element method

DOI: 10.3233/JAE-230202

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-12, 2024

Authors: Bensehila, Aissa | Bouzidi, Athmane | Takorabet, Noureddine | Ristagno, Baptiste

Article Type: Research Article

Abstract: This paper presents a parametric study of linear induction motor for design purpose. The chosen mathematical model uses a 2D formulation with magnetic vector potential A. The implementation of the model is carried out with the finite element method on the free platform Gmsh-GetDP. Circuit model is coupled to FE model so that constant voltage supply mode can be considered. This work aims to highlight the effect of the pole pair number on the characteristics and the performances of the linear induction machine through two numerical models associated to an analytical one. Furthermore, the study shows the effect of the …pole pair number on the phase imbalance and the spatial harmonic spectrum of the machine. Reducing this imbalance and higher order harmonics presence will increase machine performances. Show more

Keywords: Linear induction motor, phases imbalance, space harmonics, analytical models, FEM, EEC, pole pair number

DOI: 10.3233/JAE-230244

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-10, 2024

Authors: Heya, Akira | Inoue, Tsuyoshi

Article Type: Research Article

Abstract: Liquid hydrogen turbopumps are used in large high-performance rockets. Stable high-speed rotation is required for rocket turbopumps. The damping mechanism of the pump must suppress vibration not only in the radial direction but also in the axial direction. However, conventional damping elements using oil or rubber cannot be used due to the cryogenic temperature of liquid hydrogen. Therefore, the application of eddy current dampers to liquid hydrogen turbopumps is focused on in this paper. Although various structures of eddy current dampers have been developed, the multi-degree-of-freedom damping characteristics of dual Halbach array type eddy current dampers for liquid hydrogen turbopumps …have not yet been investigated. The variation of damping characteristics with temperature has also not yet been verified. In this paper, we propose a novel dual Halbach array type eddy current damper for liquid hydrogen turbopumps. The proposed damper can generate high damping force and can be operated maintenance-free at the cryogenic temperature. The analysis results show that the damping characteristics strongly depend on temperature and that the amplitude reduction effect is greater at low temperatures. It was also found that the proposed damper has a higher damping force density than conventional dampers. Show more

Keywords: Eddy current damper, magnetic damper, dual Halbach array, cryogenic environment, turbopump

DOI: 10.3233/JAE-230258

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-10, 2024

Authors: Sato, Daisuke | Kitagawa, Wataru | Takeshita, Takaharu

Article Type: Research Article

Abstract: This paper proposes a method to reduce torque ripple in axial gap motors by multi objective optimization of permanent magnets (PMs) shape using genetic algorithm (GA). Torque ripple is a problem because it causes vibration and noise. Conventionally, torque ripple has been reduced by quantitatively designing the PMs in the shape of multiplicative wave. However, it is difficult to optimize the objective function only by quantitative evaluation through sensitivity analysis. Therefore, in this study, the functions constituting the PMs interface shape are expressed as a Fourier-based series. The PMs is optimized by optimizing combination of their coefficients with GA. As …a result, the proposed model is almost equal to the average torque of the basic model and the torque ripple is significantly reduced. Furthermore, fillets are applied and the effect on each characteristic is verified. Show more

Keywords: Axial gap motor, torque ripple, genetic algorithm, magnet shape, Fourier-based series

DOI: 10.3233/JAE-230229

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-9, 2024

Authors: Bonnard, Charles-Henri | Jamshidpour, Ehsan | Fontchastagner, Julien | Didier, Gaëtan | Zandi, Hamidreza | Takorabet, Noureddine

Article Type: Research Article

Abstract: This paper aims to improve the efficiency, affordability, and safety of Wireless Power Transfer (WPT) devices. While wireless inductive charging is common in devices like smartphones, charging electric vehicles presents significant challenges due to high frequency electromagnetic fields that can be dangerous for users and those nearby. Current systems are expensive due to the use of specialized materials and components. By developing WPT systems with drastically reduced frequency levels, this research has the potential to significantly impact the widespread adoption of affordable, safe, and efficient WPT devices for high-power applications like electric vehicle charging. In fact, using lower frequencies allows …us to build WPT systems with far less expensive materials, e.g. no need of Litz wires and ferrites that can be replaced by single core copper wires and classical magnetic steels. The effectiveness of the method is demonstrated through simulation using MATLAB Simulink® and experimental tests. The results indicate that it is possible to maintain good performance, reduce limitations and costs, and improve user acceptance of WPT systems by considerably lowering the frequency of electromagnetic fields that are classically used in such systems. Show more

Keywords: Wireless energy transfer, Inductive Power Transfer (IPT), Electric Vehicles (EVs), wireless charging system, resonant coupling

DOI: 10.3233/JAE-230239

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-11, 2024

Authors: Hamidouche, Rayane | Mezani, Smail | Lubin, Thierry | Hamiti, Tahar

Article Type: Research Article

Abstract: This paper deals with the design and test of a contactless capacitive power converter operating at a frequency of 1 MHz, intended to supply the excitation winding of an 80 kW wound rotor synchronous machine. The methodology integrates the electromagnetic design of the rotor and its impact on the different parameters of the converter. To verify the validity of the concept, a first prototype was built by using surface-mounted capacitors grounded on the structure of a 1 MHz Class E resonant power converter. Then, a more representative capacitive contactless coupler was designed and implemented. Comparisons between simulation and experimental results …have shown the limits of the proposed contactless power transmission. Special attention was paid on losses and efficiency which are crucial for this application. Show more

Keywords: Contactless power converter, capacitive power transfer, wound rotor synchronous machine, high-frequency class E converter

DOI: 10.3233/JAE-230245

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2024

Authors: Mysiński, Michał | Jędryczka, Cezary | Demenko, Andrzej | Macyszyn, Łukasz

Article Type: Research Article

Abstract: The paper presents the results of research on the spatial distribution of the multi-phase, distributed windings in electric machines. The focus was on the analysis of the harmonics of the current linkage spatial distributions. To perform calculations for different windings patterns, taking into account the number of phases, pole pairs, and the number q of slots per pole and phase, the dedicated code was developed in the Matlab environment. Nine different multi-phase windings were studied, for which magnetomotive force (MMF ) was determined to investigate the harmonic content and total harmonic distortion. The obtained results were compared with a …reference three-phase symmetric system. Studies were also carried out on torque ripple and power density for different numbers of winding phases. Show more

Keywords: Multi-phase electrical machines, current linkage harmonics, finite element method, THD

DOI: 10.3233/JAE-230242

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-9, 2024

Authors: Zhu, Junda | Barmada, Sami | Ceraolo, Massimo | Fontana, Nunzia | Musolino, Antonino

Article Type: Research Article

Abstract: In this article, a magnetic shield for automotive Wireless Power Transfer (WPT) systems is proposed. Its innovative feature consists in the positioning of the shield, that is part of the Ground Assembly (GA) of the WPT system. Passive coils, assembled in an array-like structure to build the shields properly located near the transmitting coils are investigated. Currently, there are a variety of shielding methods, each of them with its peculiar feature. The proposed method is simple and does not increase the transmitting and the receiving coil sizes, a constraint that is often critical from a practical and an economical point …of view. The main characteristic of the proposed shielding method is the location of the shielding coils on the same level as the GA. The results here presented are validated by Finite Element (FE) based simulations and are referred to an experimental prototype of wireless charging systems for electric vehicles operating at 85 kHz with a transmitted nominal power of 3.3 kW. The results show that the proposed shield reduces the leakage magnetic flux density in the system up to 37% with a marginal impact on the transmission efficiency, complying the SAE J2954 international standard. Show more

Keywords: Resonant coil matrix, shielding, wireless power transfer

DOI: 10.3233/JAE-230207

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-16, 2024

Authors: Bergfried, Christian | Späck-Leigsnering, Yvonne | Seebacher, Roland | Eickhoff, Heinrich | Muetze, Annette

Article Type: Research Article

Abstract: Finite element models of electrical machines allow insights in electrothermal stresses which endanger the insulation system of the machine. This paper presents a thermal finite element model of a 3.7 kW squirrel-cage induction machine. The model resolves the conductors and the surrounding insulation materials in the stator slots. A set of transient thermal scenarios is defined and measured in the machine laboratory. These data are used to assess the finite element model.

Keywords: Finite element method, electrical machines, insulation system, thermal stresses, numerical field simulation

DOI: 10.3233/JAE-230233

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2024

Authors: Roger, Daniel | Rossi, Mathieu | Komeza, Krzysztof | Napieralska, Ewa | Cambier, Jérôme

Article Type: Research Article

Abstract: This article proposes a design of windings for medium-frequency transformers (MFTs) at the heart of high-power Solid-State Transformers (SSTs). With aluminum interleaved foils of the correct thicknesses, it is possible to obtain low winding losses and a very low leakage inductance well adapted to high-power SSTs able to operate in the medium-voltage grid (5–20 kV). The MFT equivalent resistance and leakage inductance are determined using an analytical model based on Dowell’s hypotheses. Several interleaved winding configurations are analyzed and compared to the standard structure made of two concentric foil coils. The experimental validation is made with short-circuit tests of an MFT …fed by a low-level square voltage source at several kHz, which can provide the necessary high current. Show more

Keywords: Solid-State Transformer (SST), medium frequency transformer (MFT), aluminum-foil winding, grain oriented electrical steel (GOES) wound core

DOI: 10.3233/JAE-230404

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-13, 2024