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

Authors: Boukhenoufa, Farouk | Ikhlef, Nabil | Aomar, Lyes | Hacib, Tarik

Article Type: Research Article

Abstract: Toroidal transformers are designed using a circular core instead of the traditional laminated rectangular core, which reduces inductance losses and increases efficiency. The primary goal of this study is to understand the cooling mechanisms involved in electrical transformers, which are critical components in power systems. Steady electromagnetic, fluid flow and temperature equations are simultaneously solved (direct method) using the finite elements method FEM of a shielded toroidal transformer. The paper focuses on creating a direct-coupled model (DCM) to understand the processes involved in electrical transformers cooling, using Magneto-AeroDynamic (MAD) models. The nonlinear models developed will be implemented and validated in …this parametric study for different inlet velocities and the number of outlet. Transformers generate heat during operation, and it’s important to control the temperature to prevent overheating and ensure reliable operation. Show more

Keywords: Shielded toroidal transformer, magneto-aerodynamic, direct-coupled model (DCM), parametric study

DOI: 10.3233/JAE-230243

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-19, 2024

Authors: Desenfans, Philip | Gong, Zifeng | Vanoost, Dries | Gryllias, Konstantinos | Boydens, Jeroen | De Gersem, Herbert | Pissoort, Davy

Article Type: Research Article

Abstract: This work compares three nonlinear solution methods for the performance of an induction motor’s magnetic equivalent circuit model with magnetic saturation. The interrelation between magnetic flux density and permeability introduces nonlinearities in the differential system of equations. Three popular nonlinear solution methods are selected for comparison, namely (i) the Gauss–Seidel method, (ii) the Newton–Raphson method and (iii) the inverse Broyden’s method. While all three methods have been applied in this context before, no comparison study has been published to the authors’ best knowledge. The study finds that the inverse Broyden’s method is most performant in terms of the number of …required iterations, the computation time per iteration and the resulting total computation time. However, for substantial saturation levels, the authors recommend a hybrid implementation of multiple solution methods to obtain robust and reliable convergence. Show more

Keywords: Magnetic equivalent circuit, nonlinear, induction motor, saturation, Gauss–Seidel, Newton–Raphson, inverse Broyden

DOI: 10.3233/JAE-230237

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-12, 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: Dahnoun, Larbi | Fontchastagner, Julien | Viguier, Christophe | Takorabet, Noureddine

Article Type: Research Article

Abstract: Electrical machines that can run at high speeds are more and more studied as they can respond to the increasing need of power onboard of aircrafts. However, to allow high-speed operability mechanical handling of the rotating parts need to be insured. In this paper an analytic design process of a novel high-speed induction machine is presented. The analytical magnetic and mechanical models developed are presented and validated with finite element simulations. The magnetic model is based on a classic equivalent electrical diagram of induction machine with a specific adaptation for the rotor leakage inductance as the squirrel cage is buried. …The mechanical model is based on a field displacement approach leading to the stress tensor in all the rotating part. A four degrees of freedom vibration analysis model considering gyroscopic effects based on Euler–Lagrange equation allows to identify the critical speeds of the system. It is shown that some geometrical parameters will have opposed effects on the two physics. Thus, an optimization-based coupling between the different physics allows to design rapidly the desired machine regarding any technical specifications as analytical models are being used. Show more

Keywords: Induction machine, high speed, analytical models, optimization

DOI: 10.3233/JAE-230241

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

Authors: Ahmed, Mohamed Essam | Merino, Inigo Garcia de Madinabeitia | Mehrgou, Mehdi

Article Type: Research Article

Abstract: The development of electric vehicles (EVs) presents the challenge of optimising electric machines to enhance efficiency, compactness, noise, vibration, harshness (NVH), and affordability, while reducing the dependence on heavy rare-earth materials to reduce the CO2 footprint of electric powertrains. This paper introduces a comprehensive optimization approach for the electromagnetic design of permanent magnet synchronous machines (PMSMs), employing a combination of Design of Experiment (DoE) and Robust Neural Networks (RNN). The optimization framework is utilised to comprehensively address the multiple objectives of an electric machine, including efficiency, noise, vibration, harshness (NVH), and cost. The integration of Artificial Intelligence (AI)-driven modelling …has resulted in significant performance improvements, achieving up to 96% total efficiency over the entire load cycle with substantial NVH reductions of up to 20 dB, while reducing the magnet rare earth materials by 35% compared to the baseline. Furthermore, this methodology reduces the simulation time by up to 90%, demonstrating the potential of combining neural network optimization with conventional finite element simulation techniques. The validation of the AI-driven optimization approach with the measurement of the baseline and optimised electric machines for efficiency and vibration is demonstrated for correlation. Show more

Keywords: Electric machines, electromagnetic optimization and modelling, design of experiment optimization, neural network-modelling, multi-objective and multi-physics optimization, topology optimization, robustness and sensitivity analysis, electric drive, E-machine efficiency, noise, vibration and harshness (NVH), electromagnetic finite element modelling

DOI: 10.3233/JAE-230210

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-13, 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. Pre-press, no. Pre-press, pp. 1-8, 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

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. Pre-press, no. Pre-press, pp. 1-9, 2024

Authors: Pauli, Florian | Hafner, Martin | Hameyer, Kay

Article Type: Research Article

Abstract: The accurate and time-saving prediction of essential machine variables (output power, torque, and efficiency) is crucial for manufacturers offering a wide power range of induction machines. Many motor variants are typically produced by axially scaling and rewinding the machine. Rescaling procedures of electromagnetic models of induction machines are in everyday use and well known. However, while a high accuracy can be achieved by rescaling in theory, more significant deviations between simulated and measured output parameters of the realized scaled device occur in praxis. These deviations can mainly be attributed to the faulty separation of effects in the distinct machine components, …such as the rotor, stator, and bearings. This paper introduces an optimization-aided modeling approach based on the induction machine’s simple equivalent circuit representation. The method is validated by measurement data obtained from many induction machines with various axial lengths and winding configurations. Show more

Keywords: Induction machine, scaling

DOI: 10.3233/JAE-230216

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

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