Showing 9 results for Electromagnetic
S. R. Mousavi-Aghdam, M. R. Feyzi,
Volume 10, Issue 3 (9-2014)
Abstract
This paper considers a new switched reluctance motor (SRM) structure aiming at high starting torque with low volume. For some applications such as EVs (Electrical Vehicles), the motor volume and starting torque is a critical point in its design. In many methods, reducing the motor volume causes reduction in starting torque and decreases the motor efficiency. Unlike conventional SRMs, the rotor pole is skewed in the proposed structure along the motor axis. An approximated two-dimensional finite element method (FEM) is used to speed up computational time and some comparisons with three-dimensional FEM are considered for more reliability. Final results show the efficiency of the proposed structure.
H. Yaghobi, H. Kafash Haghparast,
Volume 11, Issue 3 (9-2015)
Abstract
Synchronous generators are of two type’s salient pole type and round rotor type. The load angle curve of a cylindrical rotor synchronous machine comprises a single sine term only while in salient pole synchronous generators, power-angle characteristic has two terms. The first term is the fundamental component due to field excitation (the same as the cylindrical rotor) and the second term includes the effect of salient pole. In fact, this term is the second harmonic component due to reluctance torque. This paper presents a study on the new design of cylindrical solid rotor synchronous generator. In this new design, rotor of the machine is designed in such a way that the required inductance values are reached to produce reluctance torque, besides electromagnetic torque due to field excitation. In this contribution, a combination of two different ferromagnetic materials is considered in the design of the rotor. In this theory, the tight connection between the different materials is very important from a mechanical point of view. In other words, this new idea and production principal has potential in some areas after some further research and engineering. But this paper is focused on magnetic flux-carrying materials and presents a study of the new design of cylindrical solid rotor synchronous generator (NCG). Then a comparative analysis was made between this new (NCG) and conventional cylindrical solid rotor synchronous generator (CCG) and the effectiveness of the new cylindrical solid rotor from a magnetic point of view is demonstrated. In this paper, mechanical and thermal aspects of design such as vibration did not analyze.
S. Hajiaghasi, K. Abbaszadeh, A. Salemnia,
Volume 15, Issue 1 (3-2019)
Abstract
Interturn fault detection is a challenging issue in power transformer protection. In this paper, interturn faults of distribution transformer are studied and a new online detection method based on vibration analysis is proposed. Transformer electromagnetic forces are analyzed by time stepping finite element (TSFE) modeling of interturn fault. Since the vibration associated with inter-turn faults is caused by electromagnetic forces, axial and radial electromagnetic forces for various interturn faults are studied. Transformer winding vibration under interturn faults is studied through an equivalent mathematical model combined with electromagnetic force analysis. The results show that it is feasible to predict the interturn winding faults of transformer windings with the transformer vibration analysis method. Simulation and experimentation studies are carried out on 20/0.4 kV, 50 kVA distribution transformer. The results confirm the effectiveness of the proposed method.
H. Sheykhvazayefi, S. R. Mousavi-Aghdam, M. R. Feyzi,
Volume 15, Issue 4 (12-2019)
Abstract
In this paper, a new design of permanent magnet linear synchronous motor (PMLSM) for electromagnetic launcher system (EMLs) has been investigated in terms of the requisite amount of average launching thrust force and thrust force ripple minimization through finite element method. EMLs are a kind of technology used to develop thrust force and launch heavy loads with different applications including military, aerospace, and civil applications. A linear motor as a major part of the system plays a substantial role in this application providing sufficient load launch force. Cogging force and its mitigation techniques are principle challenges in linear motor operation leading to thrust ripples and detrimental effects on positioning precision and dynamic performance of the moving part. In the proposed design, some modifications have been made in the conventional PMLSM structure. Semi-closed slot construction is used for the primary and the pole shoes width has been changed to access minimum thrust ripple value. In order to attain further optimization in PMLSM’s thrust ripple profile, some other modifications have been considered in PM’s shape as arc-shaped magnetic poles. The latter assists to enforce air gap flux density distribution as sinusoidal as possible, and makes further ripple reduction. The results exhibit that the proposed structure has low weight and it is more economical compared to conventional PMLSM with rectangular shape magnet. In addition, the Average thrust force and ripple are improved providing suitable thrust force for throwing the load.
H. Shadfar, H. R. Izadfar,
Volume 16, Issue 1 (3-2020)
Abstract
Single-phase induction motors have a wide range of domestic and industrial applications. These motors have a squirrel cage rotor and their stator usually has two windings: main and auxiliary. The use of auxiliary winding in the structure of single-phase induction motors creates two unbalance and asymmetric phases. This causes to increase the spatial harmonics of the field in the air gap, and also useless electromagnetic forces. The purpose of this paper is the reduction of the electromagnetic forces in single-phase induction motors, focusing on the effect of the stator winding distribution. For this purpose, two new and different winding distributions for the motors used in the water coolers will be provided. The produced electromagnetic forces in several conventional single-phase induction motors will be compared with new and conventional windings by means of numerical methods. Numerical analysis is performed by Maxwell software. The results of this analysis indicate improvements in the quality of the performance of these motors in the presence of the provided windings.
P. Vahedi, B. Ganji, E. Afjei,
Volume 16, Issue 4 (12-2020)
Abstract
Using ANSYS finite element (FE) package, a multi-physics simulation model based on finite element method (FEM) is introduced for the multi-layer switched reluctance motor (SRM) in the present paper. The simulation model is created totally in ANSYS parametric design language (APDL) as a parametric model usable for various conventional types of this motor and it is included electromagnetic, thermal, and structural analyses. The static characteristic of flux-linkage with a phase, phase current waveform, instantaneous torque, and electromagnetic losses are predicted using the developed electromagnetic model. Carrying out 3D FE thermal analysis, the temperature rise due to the calculated core and copper losses is predicted in the developed thermal model. The transient, modal and harmonic analyses are done in the introduced structural model to determine the mode shapes, natural frequencies, displacement, and sound pressure level (SPL) in both time and frequency domains. In order to evaluate the developed simulation model, it is applied to a typical multi-layer SRM, and simulation results related to all the above-mentioned analyses are presented.
A. Rajabi, H. Lexian,
Volume 17, Issue 1 (3-2021)
Abstract
One of the important requirements in projectiles is to design a power supply for fuse consumption. In this study, an optimum design for the power supply, which includes a Miniaturized Inertia Generator (MIG), was introduced. The main objective of this research was to optimize the dimensions of the MIG with the aim of increasing energy. To achieve this, the design of experiment (DOE) was carried out through RSM-BBD to optimize six parts of the MIG. Numerical simulations were performed using Maxwell’s software. After analyzing of results by ANOVA and extracting the optimum result from the RSM, a Miniaturized Inertia Generator was fabricated with optimum dimensions. The results showed that the MIG with optimum dimensions at an acceleration of 800’g could generate 15.25V and stores the generated energy using an RLC circuit within 1ms. The experimental results which were obtained by the shock test system showed that 14.75V was charged on a capacitor within 1.1ms which has good conformity with the numerical results. The results indicated that the proposed design not only increased the MIG efficiency, but also determined the effect of each parameter on the produced energy and efficiency.
Seyed Hosein Mousavi, Aslan Nouri Moqadam,
Volume 20, Issue 0 (12-2024)
Abstract
Electromagnetic waves, with their unique properties, offer promising solutions to environmental challenges. This paper explores the utilization of electromagnetic scattering by droplets for cloud fertilization purposes. Specifically, a linearly polarized plane wave is deployed to stimulate a heterogeneous cloud medium composed of spherical droplets with varying size parameters. Through the application of Generalized Mie Theory (GMT) and Discrete Dipole Approximation (DDA) at a frequency of 28 GHz, multiple scattering phenomena and local electric fields are meticulously computed. Various scenarios of scattering, encompassing droplet diameters ranging from 500 µm to 700 µm and diverse volume fractions, are meticulously examined. Employing DDA and dyadic calculations, the exerted forces on individual spherical droplets are rigorously evaluated, with precise determination of force direction and components. The simulations robustly affirm the viability of droplet manipulation via plane wave excitation, thereby enhancing the likelihood of droplet collision and consequent cloud fertilization, ultimately leading to precipitation. Furthermore, the parameters of the incident wave can be deliberately adjusted to steer droplets towards denser regions, thereby augmenting the likelihood of successful fertilization events.
Ayoub Hamidi, Ahmad Cheldavi, Asghar Habibnejad Korayem,
Volume 20, Issue 3 (9-2024)
Abstract
This paper proposes a structure for concrete composite materials that effectively attenuates transmitted power through the composite slab across a wide frequency range. The proposed structure is practical for electromagnetic interference shielding applications. To assess its effectiveness, the proposed structure has been compared with two other structures: a traditional wire mesh used in reinforced composites and an array of helices, a cutting-edge technique for manufacturing lightweight concretes with significant improvements in shielding properties. The comparison among full-wave simulation results indicates that the proposed method leverages the benefits of both techniques. It achieves a shielding effectiveness exceeding 30 dB from low frequencies up to 8.5 GHz and beyond 55 dB from low frequencies up to 4 GHz. Furthermore, an experimental measurement was conducted to validate the full-wave simulation results. An experimental sample was fabricated according to the simulated proposed structure, and the measured shielding effectiveness confirmed the composite's capability in wideband electromagnetic shielding. Theoretically, the proposed structure can enhance the concrete's mechanical characteristics while improving its shielding effectiveness, making it suitable for designing ultra-high-performance concretes.
