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

Authors: Di Barba, Paolo | Galdi, Roberto | Mognaschi, Maria Evelina | Wiak, Sławomir

Article Type: Editorial

DOI: 10.3233/JAE-249004

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 76, no. 1-2, pp. 1-2, 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. 76, no. 1-2, pp. 3-14, 2024

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. 76, no. 1-2, pp. 15-33, 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. 76, no. 1-2, pp. 35-46, 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. 76, no. 1-2, pp. 47-60, 2024

Authors: Gong, Zifeng | Desenfans, Philip | Pissoort, Davy | Hallez, Hans | Vanoost, Dries

Article Type: Research Article

Abstract: This work proposes a novel state-space model for eccentric induction motors, allowing the use of modern control theory to diagnose the eccentricity faults and to mitigate their effects. The proposed model is derived from the inductance-based multiple coupled circuit model. Instead of actual stator windings and rotor bars placed in slots, equivalent ideally distributed stator and rotor windings are considered in the motor modelling. The self and mutual inductances that incorporate the effects of static eccentricity in motors are evaluated using the modified winding function approach. Moreover, the rotor quantities are referred to the stator side to reduce the number …of characteristic inductances. An eccentricity-oriented coordinate transformation is implemented to decouple the flux linkages in the new coordinate system and to reduce the system complexity further. Hereafter, stator currents and rotor fluxes are selected as system states, forming a fourth-order state-space model for the electromagnetic system of an eccentric motor. The proposed model is validated through comparisons with the reference data sourced from both the experiments and the finite element method. The potential of the proposed model for static eccentricity fault diagnosis purposes is explored. Show more

Keywords: Induction motor, static eccentricity fault, multiple coupled circuit approach, modified winding function approach, state-space model

DOI: 10.3233/JAE-230231

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 76, no. 1-2, pp. 61-79, 2024

Authors: Niguchi, Noboru | Hirata, Katsuhiro | Suzuki, Hironori | Okamoto, Junka | Takemura, Nozomu

Article Type: Research Article

Abstract: We propose a 6-phase 12/10 switched reluctance motor (SRM) with a polygon connection. The transformation between star and polygon connections is not equivalent to that between star and delta connections of a conventional 3-phase motor. In this paper, the transformation between star and polygon connections is theoretically described. In addition, the current condition that maximizes torque is described. Finally, the torque of both connections is compared in terms of the AC-DC current ratio.

Keywords: Switched reluctance motor, star connection, polygon connection

DOI: 10.3233/JAE-230232

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 76, no. 1-2, pp. 81-90, 2024

Authors: Okamoto, Junka | Niguchi, Noboru | Hirata, Katsuhiro

Article Type: Review Article

Abstract: We propose a magnetic-geared motor with controllable step-out torque. The operational principle which controls the step-out torque using DC currents is described. The controllable step-out torque characteristics are computed using finite element method. In addition, the load characteristics under vector control are also computed using finite element method. Two inherent characteristics are observed in this analysis result. One is that this magnetic-geared motor can generate the torque more than the step-out torque. The other is that the phase angle difference between the rotors when both rotors step out is around 30 deg. In this paper, the mechanism of these inherent characteristics …is investigated by finite element method, and these inherent characteristics are verified by carrying out measurements on a prototype. Show more

Keywords: Magnetic-geared motor, controllable step-out torque, phase angle difference

DOI: 10.3233/JAE-230240

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 76, no. 1-2, pp. 91-100, 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. 76, no. 1-2, pp. 101-110, 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. 76, no. 1-2, pp. 111-120, 2024