International Journal of Applied Electromagnetics and Mechanics - Volume 76, issue 1-2

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. 76, no. 1-2, pp. 121-133, 2024

Authors: Lodro, Mir | Korunur Engiz, Begum | Thomas, David W.P.

Article Type: Research Article

Abstract: Reliable, repeatable, and flexible testing is crucial for assessing system performance and ensuring the quality of communication. In reverberation chambers (RC), real-life propagation environments can be emulated by loading absorbers, facilitating controlled testing of the system. This work presents over-the-air (OTA) testing of the LTE-A PHY layer in the RC. We assessed the performance of the LTE-A link using key performance indicators (KPIs) such as error vector magnitude (EVM), bit error rate (BER), and signal-to-noise ratio (SNR) for varying transmitter (Tx) and receiver (Rx) gains. Additionally, we have compared the results both in an empty RC and when the RC …was loaded with RF absorbers. We used software-defined radio (SDR) for OTA transmission of LTE-A frames. The measurement results indicate that loading the RC with RF absorbers improves EVM, BER, and SNR. We also quantified the performance of the LTE-A link by changing the position of RF absorbers. Results showed that loading absorbers yielded up to 72.8% improvement in EVM, and placing absorbers closer to Rx helped reduce the amount of multipath, resulting in better transmission performance. Show more

Keywords: Reverberation chamber (RC), over-the-air (OTA), error vector magnitude (EVM), bit error rate (BER), signal-to-noise ratio (SNR)

DOI: 10.3233/JAE-230265

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 76, no. 1-2, pp. 135-146, 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. 76, no. 1-2, pp. 147-160, 2024

Authors: Aomar, Lyes | Ikhelef, Nabil | Taibi, Ahmed

Article Type: Research Article

Abstract: The aim of this paper is to present the fundamentals of an original method of shaft alignment for rotating machines based on the principle of wireless power transfer (WPT) process. WPT alignment of shafts in rotating machinery is simple and more accurate than existing methods (conventional mechanical methods or Laser-optical method) and can result in reduced power consumption and minimized mean time between failures. Shaft alignment is an important factor in the proper functioning and longevity of machinery. Proper shaft alignment ensures that the rotating shafts of a machine are in a straight line and rotate on the same axis. …This contributes to reducing the wear and tear on the bearings and other components of the machine, leading to improved reliability and longer service life. A high precision WPT alignment system has been designed with the primary coil placed in the driver machine, as an electrical motor, and the secondary coil placed in the driven machine, as a pump. The calculation of the magnetic interactions between both coils (primary and secondary coils), in particular the mutual inductance and coupling coefficient, perfectly explains deviations in the shaft (angular misalignment and parallel offset) and aligns entirely with measurement results, with a difference of approximately 4%. This new alignment method with magnetic interactions has proven effective in designing and implementing actual shaft alignment. WPT alignment offers precise shaft alignment tools for proper alignment of shafts and reduces troubleshooting issues. Show more

Keywords: Coupling coefficient, magnetic interactions, mutual inductance, shaft alignment, wireless power transfer

DOI: 10.3233/JAE-230235

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 76, no. 1-2, pp. 161-169, 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. 76, no. 1-2, pp. 171-179, 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. 76, no. 1-2, pp. 181-196, 2024

Authors: Zuidema, Gerlof | Krop, Dave C.J. | Lomonova, Elena A.

Article Type: Research Article

Abstract: A multiple-input and multiple-output planar actuator is proposed, which utilizes mechanically driven stator magnet arrays to levitate a permanent magnet mover. A state of levitation and actuation is obtained by mechanically altering the orientation of the stator magnets to control the forces and torques on the mover. A challenge for the design and control of the actuator is inverting the relationship between the force and stator magnet rotation angles, as there is no closed-form analytical solution. In this study, a feed-forward neural network is applied to model the forward relation between stator magnet angle input and a force and torque …output to reduce the forward computation time for the design process and for error estimation in real-time applications. Additionally, the neural network is considered for inverting the solution for a motion profile sampled at 1000 Hz. The developed forward model is able to calculate the forces and torques on the mover a factor 10 faster than the equivalent charge or Fourier model with an absolute error of 3 mN and 0.1 mNm for the forces and torques, respectively, and a feed-forward neural network is able to accurately learn an inverse solution for small motion profiles. Show more

Keywords: Magnetic levitation, permanent magnets, inverse problem, neural network

DOI: 10.3233/JAE-230221

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 76, no. 1-2, pp. 197-204, 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. 76, no. 1-2, pp. 205-215, 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. 76, no. 1-2, pp. 217-225, 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. 76, no. 1-2, pp. 227-240, 2024