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An efficient path integral (PI) model for the accurate analysis of curved dielectric structures on coarse grids via the two-dimensional nonstandard finite-difference time-domain (NS-FDTD) technique is introduced in this paper. In contrast to previous PI implementations of the perfectly electric conductor case, which accommodates orthogonal cells in the vicinity of curved surfaces, the novel PI model employs the occupation ratio of dielectrics in the necessary cells, providing thus a straightforward and instructive means to treat an assortment of practical applications. For its verification, the reflection from a flat plate and the scattering from a cylinder using the PI model are investigated. Results indicate that the featured methodology can enable the reliable and precise modeling of arbitrarily shaped dielectrics in the NS-FDTD algorithm on coarse grids. [ABSTRACT FROM AUTHOR]

Several types of fault current limiters have been studied so far, including superconductor based one or nonsuperconductor based one. However, it is difficult to satisfy all requirements for cost, maintainability, and current limiting performance. This study proposes another type of fault current limiter, variable transformer based one. It is supposed to be less expensive and easier to be maintained since it is based on the conventional transformer, and to be expected better current limiting performance since the magnetic circuit of the transformer is drastically changed. The magnetic circuit of the transformer is switched to be opened and to produce another one by shifting a portion of its iron core mechanically, allowing the primary and secondary electric circuit to be magnetically isolated. In that way, the electromotive force of the secondary winding could be reduced so that the secondary current could be limited. The prototype based on this concept was designed and built up, and its stational performance has been investigated. As a result, it was confirmed that the prototype shows good current limiting performances identical to the results of the previous FE analysis. Furthermore, the prototype was connected to the operating mechanism to investigate the transient performances, and as a result, satisfying current limiting performances are confirmed [ABSTRACT FROM AUTHOR]

Energy efficiency is the primary objective in optimal design of inductive power components. This goal is totally aligned with the minimization of power losses in the coils. Typically, coils have been constructed by wire winding but, more recently, the utilization of printed circuit board (PCB) constructions has become more common due to their advantages, i. e. low profile and ease of fabrication, among others. At the operating frequencies of magnetic power devices, multi-conductor cabling with litz structure is required to reduce losses. PCB loss optimization procedure involves determining the number and size of the tracks. Numerical simulation is a very powerful tool to obtain the parameters of magnetic devices. However, including the internal structure of multi-track wiring in the numerical simulation implies a very high computational cost and a low accuracy of the results, because the size of the tracks is very small. Techniques of homogenization of the cabling are used to overcome such difficulty, disregarding the internal structure in order to determine the fields in the system and their electrical equivalent by means of computational simulation. The coil losses are further determined on the basis of the characteristics of the cabling as well as of the surrounding fields. The preceding procedure has proven to be suitable for cables composed of strands of circular cross-section, but should be adjusted to apply to tracks of rectangular cross-section. In this paper, different homogenization techniques for PCB coils have been proposed and evaluated. A highly symmetric reference system is selected to reduce the computational cost of numerical modeling, but the conclusions can be applied to more complicated geometries without loss of generality. Finally, the results of the different homogenization techniques have been validated by comparison with experimental results. [ABSTRACT FROM AUTHOR]

This article delves into the study of a novel metatronic amplifier through an electromagnetic analysis. The research involves both theoretical and numerical analysis to validate the findings. Due to the complex nature of the structure, an approximate electromagnetic analysis is conducted, which still provides valuable insights into its characteristics. The mode matching technique is employed to obtain amplifier characteristics that closely match the numerical results with a high degree of accuracy. This study sheds light on the potential applications of metatronic amplifiers in various fields and highlights their unique properties that make them stand out from traditional amplifiers. [ABSTRACT FROM AUTHOR]

A novelty dual-stator brushless doubly-fed generator (DSBDFG) with magneticbarrier rotor structure is put forward for application in wind power. Compared with a doublyfed induction generator, the DSBDFG has virtues of high reliability and low maintenance costs because of elimination of brush and sliprings components. Therefore, the proposed structure has tremendous potential as a wind power generator to apply in wind power. According to the operating principle of electric machine, the DSBDFG is studied in wind power application. At first, the topology, the winding connecting, the rotor structure, the power flow chart of different operating models and the variable speed capability of electric machine are discussed and analyzed. Then, a 50 kW DSBDFG is designed. Based on the principal dimension of the design electric machine, the electromagnetic characteristics of the DSBDFG with different running modes are analyzed and calculated to adopt the numerical method. From the result, it meets the requests of electromagnetic consistency and winding connecting in the design electric machine. Meanwhile, it confirms the proposed DSBDFG has the strong ability of speed regulation. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive investigation of the optimal design of an interior permanent magnet synchronous motor (IPMSM) for electric vehicles (EVs), utilizing the hybrid artificial bee colony algorithm–support vector machine (HAS) algorithm. The performance of the drive motor is a crucial determinant of the overall vehicle performance, particularly in EVs that rely solely on a motor for propulsion. In this context, interior permanent magnet synchronous motors (IPMSMs) offer a compelling choice due to their high torque density, wide speed range, superior efficiency, and robustness. However, accurate analysis of the nonlinear characteristics of IPMSMs necessitates finite element analysis, which can be time-consuming. Therefore, research into methods for deriving an optimal model with minimal computation is of significant importance. The HAS is a powerful multimodal optimization technique that is capable of exploring several optimal solutions. It enhances the navigation capability by combining the artificial bee colony algorithm (ABC) with the kernel support vector machine (KSVM). Specifically, the algorithm improves the search ability by optimizing the movement of bees in each region generated by the KSVM. Furthermore, hybridization with the Nelder–Mead method ensures accurate and quick convergence at pointers discovered in the ABC. To demonstrate the effectiveness of the proposed algorithm, this study compared its performance with a conventional algorithm in two mathematical test functions, verifying its remarkable performance. Finally, the HAS algorithm was applied to the optimal design of the IPMSM for EVs. Overall, this paper provides a thorough investigation of the application of the HAS algorithm to the design of IPMSMs for electric vehicles, and its application is expected to benefit from the combination of machine-learning techniques with various other optimization algorithms. [ABSTRACT FROM AUTHOR]

Lower limb exoskeletons with actuators aids disabled individuals in walking. However, the exoskeleton weight is greater than that of conventional medical devices such as orthoses and walking frames. In this study, we propose a novel strain wave gear for light exoskeletons, which is 50% lighter than conventional commercial strain wave gears. This gear uses magnets and yokes, rather than mechanical elements. The thin-walled elastic cylinder is deformed by the magnetic force in the gear, and the torque is transmitted by tooth engagements. The maximum torque was calculated to be 10.5 Nm using flexible multibody dynamics analyses with a magnetic force database. The outcome was efficient in development of lightweight machines. [ABSTRACT FROM AUTHOR]

This article proposes a simple method to calculate a current vector trajectory for the enhanced operation of the electric power generation system based on a synchronous reluctance machine (SynRM). Owing to magnetic saturation and cross magnetization, the performance and the torque capability of a SynRM vary according to the position and the value of the stator current. State-of-the-art control methods usually assume parameters with constant values, especially the inductance, neglecting saturation, leading to possible uncertainty in the machine operation. Therefore, a current vector trajectory to operate this type of machine, as a generator, in an extended speed range, with enhanced performance and considering magnetic saturation is proposed. A straightforward algorithm based on the inductance characteristic of the machine is used to calculate the trajectory of the stator current vector. This trajectory is evaluated via the numerical simulation of an experimentally validated finite-element model of a SynRM. The results show that the proposed current vector trajectory can improve the torque capability to 5% concerning the estimated trajectory without considering saturation. Experimental results are also provided to demonstrate the enhanced operation of the generator. [ABSTRACT FROM AUTHOR]

The main goal of the present study is to carry out one-way coupled computations of electromagnetics and heat transfer for a simplified version of a switchgear and to reveal the applicability of the computational approach. In our computation, we introduce the joule losses that we obtain from the electromagnetic computations to a thermal solver as heat load. In order to reach the goal, we compare the temperature values that we obtained at eight different measurement points by performing computations and experimental measurements. In general, the distributions of the obtained temperature values are quite similar. The notable difference in the mean values of the obtained temperatures might result from limitations of one-way coupled approach where we have to neglect temperature dependency of the electrical properties during the electromagnetic computations. [ABSTRACT FROM AUTHOR]

The efficiency of permanent magnet synchronous hub motors (PMSHM) used in light electric vehicles (EVs) is lower than that used in commercial EVs. Therefore, in this study a high-efficiency radial-flux outer-rotor PMSHM was designed for light EVs. The high-efficiency motor will contribute to the reduction of the power consumption demand from the batteries of EVs, the longer life of the batteries and the longer uninterrupted operation of the system. The optimization objectives, such as motor sizing, number of slots and poles, air gap length, material selection, stator winding structure, stator slot shape, magnet thickness, and cutting method for stator sheets were considered to ensure high efficiency and low cogging torque. In this study, three validation stages were followed; electromagnetic analyzes with FEM, analytical calculations, and finally experimental validation. First, the design parameters of the motor were determined based on the analyses results obtained using ANSYS Maxwell software, and then validated both with the analytical calculations and experimental results. The comparison results show that the design data of the motor at the rated speed agree well with the analytical calculations and test results. After obtaining the optimized motor design, the motor was installed on a prototype electric car for the road test. During the test drive, the motor performed successfully and operated compatibly with the rest of the electric vehicle systems such as the motor driver and the battery. [ABSTRACT FROM AUTHOR]

In this article, a hybrid wireless power transfer system, which combines induction heating (IH) and inductive power transfer functionalities, is proposed to improve the performance of a domestic IH application with small loads weakly coupled to distant inductors. Considering the basic single-inductor domestic IH application, the proposed system adds a secondary inductor with a series compensation capacitor directly attached to the small ferromagnetic cookware. The extended distance can be used to implement the glassless induction concept, where the ceramic glass of typical cooktops is substituted by the kitchen surface itself. The design of the secondary coil is carried out by means of a combination of finite-element and electrical simulations. A design process, including the housing of the resonant capacitors and the selection of the secondary winding number of turns and cabling, is presented. As a result, a prototype is implemented and tested under working conditions up to 1500 W at several distances. Experimental results validate the electrical modeling and simulation. Moreover, thermal results confirm the feasibility of the proposal and validate the adopted strategies for the capacitor housing. [ABSTRACT FROM AUTHOR]

Axial flux permanent magnet (AFPM) machines are good candidates for electric vehicle applications due to their high torque density, improved efficiency, and better flux distribution; thus, they are often used. A dual-rotor single-stator AFPM machine with four differently shaped permanent magnet (PM) rotors is investigated. The main aim of this paper is to enhance the average torque while minimizing the cogging torque and torque ripples at the expense of low PM volume. The proposed machines are analyzed in terms of flux linkage, back-EMF, cogging torque, average torque, and torque ripples. The analysis reveals that the machine with an arc-shaped PM rotor performs better than the others. In addition, the trapozoidal arc-shaped PM used in the AFPM machine outperforms the hexagonal, skew arc, and traditional trapezoidal PMs. The torque density of the trapezoidal-shaped PM machine is 40.23 (KNm/ m 3 ), while that of the hexagonal shape is 32.46 (KNm/ m 3 ), that of the skew arc shape is 39.78 (KNm/ m 3 ), and that of the arc shape is 50.38 (KNm/ m 3 ). [ABSTRACT FROM AUTHOR]

This work presents a novel integrated device that combines a hybrid stepping motor (HSM) and a planetary gear train (PGT) reducer as a compact structural assembly. In this study, a systematic design process was developed to efficiently implement the integrated device. By applying the gear profile on the rotor and the stator, a 9:1 two stages PGT reducer is integrated with a standard 42 type 2-pole stepping motor. The quadratic interpolation method was applied to derive the optimal design of the geometric configurations of the HSM. The electromagnetic characteristics and output performance of the integrated device, including flux linkage, back-emf constant, holding torque, and output torque, were analysed. Finally, the output performance between an existing design and the novel integrated design were compared. The two designs had similar output and holding torque, but the torque ripple was approximately 44.7% lower in the integrated device from 30% to 16.6%. In addition, the axial space arrangement was reduced by 5.2% from 67.7mm to 64.1 5mm, and the torque density was improved by 4.4%. [ABSTRACT FROM AUTHOR]

In this article, a method for removing the return loss effect during shielding effectiveness (SE) measurements for a shielding enclosure is proposed. According to the IEEE 299.1 standard, a receiving antenna is located inside the enclosure to be measured, and this antenna measures the signal loss after passing through the enclosure. The receiving antenna experiences the return loss at its input, and this return loss increases the SE because the occurrence of the return loss is equivalent to the increasing loss when passing through the enclosure. The IEEE 299.1 standard provides a method for removing the return loss effect. The return-loss removal is only effective, however, when the receiving antenna has an input impedance that does not significantly change, remaining almost constant at the adjacent frequencies. The proposed method generalizes the return-loss removal, and thus the return loss effect can be removed irrespective of the input impedance condition of the receiving antenna. As the return loss is removed for any type of the receiving antenna, the SE can be accurately measured to prevent an overestimation of the SE. [ABSTRACT FROM AUTHOR]

The idea of the Kelvin transformation is extended to analyze the eddy current testing (ECT). The Kelvin transformation was originally proposed to solve the Poisson equation on the entire unbounded domain. When it was first applied to electromagnetic quasi-static problems, it was assumed that the analysis domain is surrounded only by air and nothing is inside the exterior domain. The analysis domain is truncated by a circular boundary in two dimensions and spherical in three dimensions, and another circular/spherical domain for emulating the exterior domain is connected through unknown equivalent boundary conditions. In this article, the Kelvin transformation is reformulated to derive the conductivity and permeability in the exterior domain, which conserves the conformal symmetry of Maxwell’s equations. Utilizing the derived conductivity and permeability, the materials can be both in the interior and exterior domains or even across the truncated boundaries. Some numerical examples are demonstrated to validate the proposed method. As an application of the proposed method, the electromagnetic analysis of the ECT model is performed. [ABSTRACT FROM AUTHOR]

In this study, fuzz structures in tungsten surfaces are artificially generated using the midpoint displacement algorithm (MDA) based on the random fractal. The finite-difference time-domain (FDTD) method is employed to simulate electromagnetic wave propagation in the fuzz structures with different fractal dimension sizes. To analyze electromagnetic penetrations and reflections around the fuzz structures, we adopt the three-dimensional empirical mode decomposition (TEMD) to decompose simulation results by FDTD in the spatial frequency domain. The computation results showed that the distribution of electric field intensity is decomposed into 3-D intrinsic mode functions (IMFs), indicating resonances triggered by electromagnetic waves hitting the fuzz structures in the tungsten surface from high spatial frequency to low spatial frequency. These decomposed IMFs revealed the optical properties of fuzz structures regarding the relationship between fractal dimension sizes and the electromagnetic penetrations and reflections in the tungsten surface. [ABSTRACT FROM AUTHOR]

A new coordinate system is proposed for the purposes of analysis of far-field radiation from a localized source at the origin. The proposed stereographic coordinates exhibit no singularities over the far-field hemisphere, making them a good choice for automated radiation pattern analysis. Finally, it is shown that Ludwig polarization basis, commonly used to represent polarization of the far-field radiation, arises naturally, as a coordinate basis when one uses stereographic coordinates. [ABSTRACT FROM AUTHOR]

In this article, a two-dimensional hybrid finite-element formulation is proposed to further reduce the computational time required for the time simulation of superconducting (SC) bulks. Low computational time formulations are important for the design stage of electrical machines with superconductors, where optimization tools are typically used. The proposed hybrid formulation is based on the partitioned E-H electromagnetic scheme (EHS) formulation and the magnetic vector potential formulation (A-formulation). The EHS formulation is used to solve the domains with highly nonlinear electric materials, while the A-formulation is used to solve the nonelectric domains. The main characteristics of the EHS are its partitioned formulation, where the matrix form of Ampère's and Faraday's laws is separated and computed a priori, and the electric resistivity is defined at each node. The EHS formulation is first compared with the H-formulation for a single SC domain and then integrated with an A-formulation and compared with the H and H-φ formulations to simulate a bulk surrounded by air. Results verify the excellent accuracy of the EHS and A-EHS formulations, and a promising reduction of computational time is observed, with more emphasis on low levels of magnetization of the SC sample. When compared with the H-φ formulation, a time reduction between 48% (6 T) and 90% (1 T) is obtained. [ABSTRACT FROM AUTHOR]

A novel approach to computing time-harmonic solutions of Maxwell’s equations by time-domain simulations is presented. The method, electromagnetic-WaveHoltz (EM-WaveHoltz), results in a positive definite system of equations, which makes it amenable to iterative solution with the conjugate gradient method or with generalized minimal residual method (GMRES). Theoretical results guaranteeing the convergence of the method away from resonances are presented. Numerical examples illustrating the properties of EM-WaveHoltz are given. [ABSTRACT FROM AUTHOR]

• This study presents a comprehensive multi-physics FEM analysis of an air-core reactor within a solid-state fault current limiter, focusing on thermal, electromagnetic, and electrostatic aspects under both normal and fault conditions of the test system. • FEM model-electric circuit coupling is validated with a 380 V test prototype, and the current results of the high-voltage simulation are supported by PSCAD results to show simulation accuracy. • During the thermal studies, convection, radiation and convection mechanism applied to air-core reactor and results shows that thermal stability is maintained during the fault limiting mode. • Analysis revealed significant increases in electric field, magnetic flux density and forces acting on the air-core reactor's windings during the fault condition of the test system. • The solid-state FCL topology, incorporating the modeled air-core reactor, reduced the fault current by 85.32 % during the fault scenarios within high-voltage simulations. This study presents a comprehensive multi-physics modelling of an air-core reactor operating within a solid-state fault current limiter. By utilizing an air-core reactor in the solid-state fault current limiter, it is aimed to avoid magnetic saturation and assess a conventional fault current limiting device within a contemporary fault current limiter topology. Within the employed fault current limiter topology, the air-core reactor not only limits fault current during grid faults but also carries nearly the entire network current under normal operational conditions. Therefore, the performance of air-core reactor is investigated through thermal, electromagnetic and electrostatic aspects for normal and fault conditions. A 380 V test prototype is employed to validate the coupling of reactor model and electric circuit dynamics in the simulations. Furthermore, current results of high voltage simulations are supported by PSCAD results to reveal the results accuracy. During the operation of air-core reactor in normal and fault cases, the distribution of heat originating from eddy and resistive losses was examined through convection, radiation and conduction mechanisms. Moreover, the electric field intensities affecting the reactor are obtained for different operating conditions through electrostatic analysis, whereas the electromagnetic analysis reveals the magnetic flux densities and magnetic forces acting on the reactor. [ABSTRACT FROM AUTHOR]

• Brazing has many advantages over welding; it could be a real alternative. • A test rig has been developed to join DN200 pipe sections with induction brazing. • Design supported by electromagnetic and thermal analysis; to be validated by tests. • 99 percent of analysis run time saved with 2D analysis for spiral induction coil. • Heating power is concentrated to the first ∼2 mm of the pipe thickness. The DEMO first wall blanket components will be exposed to high neutron fluence and high levels of thermal energy, the latter being removed by a coolant fluid transmitted out of the reactor via service piping. Due to the thermal and nuclear loading on the first wall, the components will need to be periodically removed and replaced. Installation of new blankets requires the joining of their service pipes by remote handling. Brazing is one of the alternatives that are considered for joining the service pipes of the DEMO breeding blankets. This technique has great potential and has several major advantages over welding. The Fusion Technology Department of HUN-REN Centre for Energy Research (CER) has been working on the development of a viable brazing concept of thick, large bore pipes inside the ports of DEMO. Induction has been chosen as the heat source for the brazing operation, which is a well-studied technology and has many uses in the industry already. However, brazing in this size is a completely new horizon for induction heating so CER's work includes a significant amount of development. Firstly, the coil is naturally a bespoke component, which has been optimized by electromagnetic analysis. Secondly, a test rig has been designed and manufactured in-house by CER, to test the performance of the induction heater in a real scenario. This paper outlines the development strategy of the induction brazing of DEMO's large bore pipes. [ABSTRACT FROM AUTHOR]

The nonstandard finite-difference time-domain (NS-FDTD) method is implemented in the differential form on orthogonal grids, hence the benefit of opting for very fine resolutions in order to accurately treat curved surfaces in real-world applications, which indisputably increases the overall computational burden. In particular, these issues can hinder the electromagnetic design of structures with electrically-large size, such as aircrafts. To alleviate this shortcoming, a nonstandard path integral (PI) model for the NS-FDTD method is proposed in this paper, based on the fact that the PI form of Maxwell's equations is fairly more suitable to treat objects with smooth surfaces than the differential form. The proposed concept uses a pair of basic and complementary path integrals for H-node calculations. Moreover, to attain the desired accuracy level, compared to the NS-FDTD method on square grids, the two path integrals are combined via a set of optimization parameters, determined from the dispersion equation of the PI formula. Through the latter, numerical simulations verify that the new PI model has almost the same modeling precision as the NS-FDTD technique. The featured methodology is applied to several realistic curved structures, which promptly substantiates that the combined use of the featured PI scheme greatly improves the NS-FDTD competences in the case of arbitrarily-shaped objects, modeled by means of coarse orthogonal grids. [ABSTRACT FROM AUTHOR]

Electromagnetic attacks, which in fact exploit essentially the magnetic field generated by ICs, are commonly used by adversaries to retrieve secret information manipulated by integrated circuits. Due to the increasing resolution and effectiveness of EM equipment used to perform these attacks, it is becoming increasingly difficult to design secure circuits robust enough to resist these attacks. The contribution of this article is threefold. First, it describes a simulation flow of the magnetic field radiated by ICs. The introduced flow is based on an industrial voltage drop tool: ANSYS RedHawk. Second, it introduces a methodology to localize the root cause of leakages in ICs as well as EM hotspots, i.e., positions above the IC surface, where an adversary can place its probe to capture secrets. The latter contribution is based on the concept of noise to add, which is introduced in this article in order to overcome the absence of noise in simulations (noise which is omnipresent in practice) that limits their interpretability. Finally, the article demonstrates the soundness of the proposed solution by confronting simulation results with measurements. [ABSTRACT FROM AUTHOR]

A temperature rise occurs when an electrical machine is fully loaded. The winding insulations of high-speed permanent magnet synchronous machines (PMSMs) are the most temperature-sensitive components, which can impact the machine's longevity. Thus, recently, prediction for high-speed PMSM winding temperature has been given more and more attention. Thermal analysis by numerical (computational fluid dynamics (CFD) and finite element method (FEM)) and analytical lumped parameter thermal network (LPTN) methods have been widely used to estimate the temperature of totally enclosed fan cooled axial ventilation system (TEFCAVS) machines. Although numerical methods have more accuracy, their computation wastes time. Therefore, LPTN is being utilized in this paper due to the fastness of its computation. Firstly, estimated losses of high-speed PMSM with TEFCAVS via electromagnetic analysis, including copper, iron, permanent magnet (PM) eddy current, sleeve eddy current, and mechanical, are coupled to the LPTN model, which acts as heat sources for temperature prediction. Moreover, analysis shows that slot windings' maximum temperature exceeds the winding insulation class with initial cooling configuration. Secondly, in order to mitigate slot winding temperature, the sensitivity study for liner conductivity, air gap's heat transfer and lamination to housing's contact is conducted by LPTN to identify which thermal parameter has more influence on mitigating the maximum temperature of the slot winding. Investigation shows that improving an air gap's heat transfer has more influence than other parameters for mitigating slot winding maximum temperature below its insulation class. Lastly, the machine is designed and tested with the best thermal-sensitive parameters. Then test results for the maximum temperature of the winding are compared with estimated results to ensure the proposed LPTN correctness, and the calibration process confirms LPTN accuracy. [ABSTRACT FROM AUTHOR]

Elliptic curve cryptography (ECC) is one of the commonly used standard methods for encrypting and signing messages which is especially applicable to resource-constrained devices such as sensor nodes that are networked in the Internet of Things. The same holds true for wearable sensors. In these fields of application, confidentiality and data integrity are of utmost importance as human lives depend on them. In this paper, we discuss the resistance of our fast dual-field ECDSA accelerator against side-channel analysis attacks. We present our implementation of a design supporting four different NIST elliptic curves to allow the reader to understand the discussion of the resistance aspects. For two different target platforms—ASIC and FPGA—we show that the application of atomic patterns, which is considered to ensure resistance against simple side-channel analysis attacks in the literature, is not sufficient to prevent either simple SCA or horizontal address-bit DPA attacks. We also evaluated an approach which is based on the activity of the field multiplier to increase the inherent resistance of the design against attacks performed. [ABSTRACT FROM AUTHOR]

This work presents a novel integrated device that combines a hybrid stepping motor (HSM) and a planetary gear train (PGT) reducer as a compact structural assembly. In this study, a systematic design process was developed to efficiently implement the integrated device. By applying the gear profile on the rotor and the stator, a 9:1 two stages PGT reducer is integrated with a standard 42 type 2-pole stepping motor. The quadratic interpolation method was applied to derive the optimal design of the geometric configurations of the HSM. The electromagnetic characteristics and output performance of the integrated device, including flux linkage, back-emf constant, holding torque, and output torque, were analysed. Finally, the output performance between an existing design and the novel integrated design were compared. The two designs had similar output and holding torque, but the torque ripple was approximately 44.7% lower in the integrated device from 30% to 16.6%. In addition, the axial space arrangement was reduced by 5.2% from 67.7mm to 64.1 5mm, and the torque density was improved by 4.4%. [ABSTRACT FROM AUTHOR]

This article introduces the design of a system capable of heating two magnetically independent ferromagnetic loads placed on different horizontal planes, which uses a combination of induction heating and inductive coupling, called inductively coupled heating. The system uses a single primary inductor acting as a transmitter to transfer power to a secondary inductor attached to the bottom load, which is connected electrically with a third inductor that heats the top load. Since power of the whole system is supplied by a simple half-bridge inverter, the ratio of the delivered power to each of the loads, which is critical for cooking results, is entirely dependent on the system's geometry, coil's number of turns, and compensation capacitors. A finite-element model is used to simulate the magnetic fields generated by inductor currents and calculate the impedance matrix. With the impedance, capacitor values and inductors’ number of turns are selected with the objective of achieving a high power ratio between the top and bottom zones, as well as minimizing stress in the electronics. First, a prototype was built to validate the impedance results in the small-signal regime, and then, the full power regime was used to verify power and current simulations [ABSTRACT FROM AUTHOR]

Although the underlying phenomena when grounding electrodes discharge lightning currents are very complex, it is possible to derive simple formulas of impulse characteristics that allow for important engineering estimates. The interest in simple formulas was recently renewed, resulting in many contributions in the literature. In this paper, a parametric analysis is performed by a simulation of time-domain responses, with parameters in broad ranges. From this study, new formulas of impulse characteristics have been derived, including the expressions for ranges of parameters when grounding electrodes exhibit dominant inductive, resistive, or ionization effects. New formulas are compared with the existing ones, with experimental results, and their accuracy has been investigated. [ABSTRACT FROM AUTHOR]

The present work deals with steady state air flow analysis of electric motor having 20 hp rating running at 1450 rpm. The motor is being used to run the belt pull system to drive the exhaust fan in the industry. Air flow analysis of electric motor is carried out to predict temperature distribution over the motor. The modeling of the complete motor is done in CATIA. Meshing of whole geometry is done in ICEM CFD14.5. Results are obtained using FLUENT. In this research only copper losses and iron losses are taken into consideration based on the output obtained from electrical simulation software. The copper and iron losses are found out from electromagnetic analysis using Motorsolve software. Losses are treated as heat source or input to find out temperature distribution. To improve the accuracy, the computational fluid dynamics (CFD) analysis is performed by considering the air flow around casing and fins and thermal generation due to the losses. It is observed that there is a significant rise in temperature on casing and on fins for 30 °C ambient temperature. [ABSTRACT FROM AUTHOR]

• Electromagnetic analyses are performed adopting the ITER Global Model based on the flux-edge element formulation. Both Lorentz loads and Maxwell loads on CN HCCB TBM-set during four typical disruption scenarios are numerically calculated. • Equivalent electrical resistivity and corrected B-H curve based both on the effective volume ratio are employed in Lorentz loads calculation and Maxwell loads calculation, respectively, to basically eliminate the influence brought by model simplification. • Comparison is made between Maxwell load results obtained in this work and those presented in our previous research. Difference is observed and the results of previous work which show better consistency with the analytical ones are considered to be more convincing. • The combination of Lorentz loads and Maxwell loads on two HCCB TBMs is presented and their respective contributions to structural response are discussed. Electromagnetic (EM) loads (i.e., Lorentz and Maxwell loads) on the Chinese (CN) Helium-Cooled Ceramic Breeder (HCCB) Test Blanket Module set (TBM-set) as well as on the installation Frame are numerically estimated using the ANSYS software. ITER Global Model (IGM) based on the edge-flux formulation is utilized in EM analysis. The current Preliminary Design (PD) model of HCCB TBM-set is taken into account. Four typical plasma Major Disruptions (MDs) are considered in accordance with the system load specifications. It is discovered that both kinds of EM loads are dominated by the radial component. The MD_DW_III is the worst case in terms of Lorentz loads, while the considered MDs have almost the same maximum Maxwell loads which appear under the condition of plasma start of burn. Regarding the EM loads on two TBMs, the Maxwell Force (MF) is much larger compared with the Lorentz Force (LF), however the Maxwell Torque (MT) is far smaller than the maximum Lorentz Torque (LT). The obtained results will be applied in corresponding structural analysis to ensure the integrity of HCCB TBM-set in the further work. [ABSTRACT FROM AUTHOR]

This work analyzes the impact of the physical factors (frequency effect, water content, and porosity level) on the voltages developed along the wind turbine (WT) subjected to lightning strikes. The analysis is performed considering a realistic grounding system (GS) where the full-wave electromagnetic (ES) software FEKO/Altair Engineering® calculates the GS harmonic impedance (HI) for 100 Hz to 10 MHz. For this purpose, six soil models [Visacro–Portela, Portela, Visacro–Alípio, Alípio–Visacro, Datsios–Mikropoulos, and Archie] and their transient responses are assessed. Comparisons are made with those assuming a frequency-constant (FC) soil at the dry condition. The GPR on the GS and the voltages on the tower base and nacelle are calculated using the software ATP® for the transient analysis. Results show a significant impact on HI with the physical factors, being remarkable at high frequencies and for high-resistive soils. Consequently, a notable decrease in the GPR peaks is seen compared with those with FC soils. These soil models and the lightning currents influence voltages at the nacelle and tower base. Results demonstrated that the Portela model predicts a more significant decrease in the voltages, and Datsios-Mikropoulos's model provides closer responses to the FC soil. Increasing porosity yields larger peak values, and increasing water content produces lower voltages. • The frequency effect, water content and porosity level are investigated. • Soil electrical parameters are dependent on the physical factors. • Wind turbines located on realistic soils are modeled. • Transient voltages on wind turbines are notably affected by the physical factors. [ABSTRACT FROM AUTHOR]

In this article, RF wave and electron beam interaction behavior of the side-coupled cavity (SCC) structure, operating in the transverse magnetic (TM) mode has been investigated using the field matching technique. For the analysis, Vlasov–Maxwell’s equations have been used to describe the EM fields in the beam present region of the SCC structure. All the harmonics present in the structure have been considered for the analysis of the dispersion characteristics and growth rate of the SCC structure. The temporal growth rate behavior with respect to the different beam parameters has also been explored. To validate the developed analysis, computed dispersion values have been compared with those of the simulated, for the special case (i.e., $r_{\text {e}} =0$). Furthermore, the analytically temporal growth rate has also been compared with the simulated values. The obtained computational and simulated values have been found in agreement within ±5%. [ABSTRACT FROM AUTHOR]

This article presents the design and development of the permanent capacitor split-phase ceiling fan motor with enhanced air delivery per unit power consumption. An existing single-phase induction motor ceiling fan is taken as a reference, and experimental performance is validated against finite element analysis (FEA). One factor at a time or monothetic analysis for existing lamination with turns in both the windings, a permanent capacitor connected in series with the auxiliary winding, an air gap length, stack length as parameters, and different loading is carried out in detail. Design modifications are proposed in stator lamination, and rigorous series of simulations are carried out. Two new motors are designed and prototyped for performance improvement, keeping the outer diameter of the motor same as an existing motor. The overall saturation of the motor is reduced by modifying the slot profile of the winding slots and increasing the overall volume of the motor. The designed motors are analyzed using FEA, and prototypes are tested for electrical performance and air delivery as per IS 374 standard. Both the results of prototypes show significant improvement in the power consumption and the air delivery with blades of an existing fan justifying the commercial viability of the improved design. [ABSTRACT FROM AUTHOR]

This paper explores a new structural design of armature splicing to reduce the machining requirements of maglev guideways. The paper presents the magnetically supported structure and working principle of magnetic levitation worktable machine tools. Rectangular tooth splicing structures for extended long-stroke maglev guideways are designed, and corresponding finite element analysis models are established. After calculating the static three-dimensional magnetic field with the help of ANSYS software, the electromagnetic force produced by the magnetic levitation electromagnet group decreases linearly with increasing splice clearance of the armature and increases linearly with the increasing number of splice teeth. The smaller the number of teeth is or the larger the clearance value is, the more pronounced the change is. When the number of teeth, the width of the teeth and the clearance of the splice are kept constant, the electromagnetic force increases with increasing tooth depth, and a change in the tooth width has little effect on the electromagnetic force. [ABSTRACT FROM AUTHOR]

A new scalable small‐signal model for 0.1 μm AlGaN/GaN HEMT up to 110 GHz is presented in this paper. The taps between the gate/drain manifold and fingers on the device has been investigated and included in the equivalent circuit. In addition, to ensure high scalability, a set of scaling rules are presented. A novel extraction procedure for extrinsic capacitances using full‐wave electromagnetic (FW‐EM) method has been introduced along with corresponding structures used for EM simulation. The nonlinear dependence of the extrinsic inductances on the gate‐width has been accounted for by a new scaling rule, which can be used to extract their value from measurement data. To guarantee the stability of the scaling coefficients, two devices with different gate‐width have been utilized for their generation. The proposed scalable model has been verified using 0.1 μm AlGaN/GaN HEMT devices with different gate‐widths and different gate‐fingers. The experiment results show good agreement between model and measurement S‐parameters up to 110 GHz. [ABSTRACT FROM AUTHOR]

The Lorentz-force-driven stamping process is a newly developed forming process, which combines the advantages of the quasi-static stamping and electromagnetic forming to a certain extent. It involves complex physical problems such as strong electro-magneto-mechanical interactions and considerable deformation. Therefore, it is still a challenge to accurately predict the electromagnetic parameters (coil current and Lorentz force, etc.) and workpiece deformation (forming height and material flow) during the stamping process for different forming conditions. To solve this problem, taking the cylindrical cup forming of 5052-O aluminum alloy sheet metal as an example, a numerical method based on the iterative calculation of a circuit-electromagnetic model and an electromagnetic-mechanical model is developed and systematically validated. Numerical tests show that, compared with the non-iterative model, the proposed iterative mode can significantly improve the simulation accuracy for different forming conditions (such as varied discharge voltages and initial gaps between the coil and the punch). It has been confirmed that the iterative procedure can well consider the effect of the increased distance between the coil and the punch on the calculations of electromagnetic and mechanical parameters. Furthermore, numerical and experimental investigations for a Lorentz-force-driven stamping system using a discharge circuit with an additional crowbar branch are carried out, showing the simulation data of discharge current and workpiece deformation agree well with that of experiment measurement. This confirms the applicability of the proposed method to different discharge circuits. [ABSTRACT FROM AUTHOR]

This article proposes a method to design a three-stage induction coilgun system using the finite-element method (FEM). The system is designed to launch a 21.5 kg projectile. The method which is used to calculate the mutual inductance and the mutual inductance gradient between the two coils is expressed. Furthermore, the variation of mutual inductance and its gradient with respect to the distance between the two coils is indicated. The system parameters (i.e., coil currents, mutual inductance, mutual inductance gradient, force, velocity, and magnetic field distribution) are calculated and analyzed utilizing ANSYS Maxwell software. To verify the performance of the initial design, its analytical model is developed and validated in MATLAB software. The results of the analytical model are compared with the results obtained from the FEM method, and it is shown that they are well-matched in all waveforms. Besides, the efficiency of the system is improved through optimization by applying a genetic algorithm (GA). In this way, the efficiency of the system is enhanced from 29% to 36.6% and also the muzzle velocity is increased from 128 to 143 m/s. This method can be used to design a large-scale multistage induction coilgun (MSIC) for launching massive projectiles and reach high velocities. [ABSTRACT FROM AUTHOR]

A novel six-pole five degrees of freedom (5-DOF) ac hybrid magnetic bearing (HMB) is put forward in this article, which can obtain large suspension force density, high critical speed, and reduce the nonlinearity of radial suspension force. First, the structure and suspension principle are introduced in detail and then the mathematical models of the radial and axial suspension force are derived based on the equivalent magnetic circuit analysis. Second, the main parameters are designed according to the given maximum radial and axial bearing capacities. Finally, the prototype of the six-pole 5-DOF ac HMB is established by the 3-D finite-element analysis software Magnet. Moreover, the electromagnetic analysis is carried out to verify the rationality of the magnetic circuits and suspension mechanism. Furthermore, the force–current relationships are calculated. The research results have shown that the proposed six-pole 5-DOF ac HMB has reasonable structure and good suspension performances. [ABSTRACT FROM AUTHOR]

Movement is the primary reason for the existence of many electrical machines. Modeling movement can often be very expensive. In some circumstances where the moving object is invariant in the direction of motion, this approach can be simplified using methods, such as the Minkowski transform. In the general case, where the moving object is not as above, many solutions of nonlinear equations by time-stepping techniques can be required. Some methods developed in the past have stood the test of time and others have proved to be less useful. [ABSTRACT FROM AUTHOR]

This article presents a technique for the computation of the monostatic radar cross section of complex objects based on a combination of macro-basis functions (MBFs) and the multilevel fast multipole algorithm. An initial pool of excitation-independent MBFs is first obtained, generating the corresponding reduced coupling matrix as well as the multipole data. For each excitation, ray-tracing processing is performed, extracting a number of critical points that are used to obtain a mask that allows to dynamically select the basis functions to be considered in the analysis. This strategy allows a noticeable reduction in the size of the problems with minimal CPU-time preprocessing overhead. [ABSTRACT FROM AUTHOR]

High values and uneven distribution of the transient ground potential rise (TGPR) at grounding grid conductors in cases of lightning can disrupt the system safety and reliability. To assess the transient performance of grounding grids under lightning currents, a parametric analysis was performed with a computer simulation of 13,978 cases of time-domain responses with a broad range of parameters. From this study, graphs of impulse impedance and a new formula for the effective area have been developed. The graphs are general, describe grids of any shape and size and depend on three parameters: grid conductor spacing, the resistivity of earth, and the zero-to-peak time of the lightning current pulse. Although the parametric analysis was based on a uniform soil model, the graphs can also be used for the two-layer soil model. In this paper, graphs and formula are used in a simple procedure to estimate the effectiveness of a mitigation measure to reduce the TGPR by increasing the grounding grid mesh density in a limited area around the current injection points. The results from the procedure are compared with experimental results, and the application and limitations of the procedure are illustrated by considering large grounding grids as examples. [ABSTRACT FROM AUTHOR]

When lightning strikes a transmission line tower or shield wires, electromagnetic waves propagate through the tower back and forth, increasing the voltage across insulator strings. This can eventually lead to a back-flashover (BF), which may cause damage to equipment or costly power outages. To calculate the over-voltages and predict the probability of a BF, an accurate model of the tower and its grounding system is needed in electromagnetic transient (EMT) type simulators. There are a number of theoretical models for the equivalent circuit of a transmission tower. However, they either are not accurate enough or they are derived for a certain type of transmission tower, which limits their applicability. Numerical electromagnetic analyses have less simplifications compared to the theoretical solutions and are by far less expensive than field measurements. They also have the flexibility to analyse any type of tower. In this paper, the direct method for the measurement of tower impedance is implemented by NEC4 and applied to a 400-kV double circuit tower with all its details. The process of obtaining the wire network of the tower used in this paper is completely automated and it can be applied to any other type of transmission tower. The results of the numerical simulations are compared to those obtained with existing tower models. The developed model in this paper is capable of considering all the details of the tower and including the finite resistance of the ground and grounding electrodes. [ABSTRACT FROM AUTHOR]

One of the most accurate approaches to the lightning-related transient analysis of grounding systems in layered soil is based on the method of moments solution of the integral form of the Maxwell equations. The practical application of this rigorous model to large systems is hindered by a great amount of computer time required for the numerical integration of oscillatory and slowly convergent Sommerfeld integrals (SI). As a result, approximate methods that avoid the solution of SI, e.g., image theory-based methods, are often used for computation of the response of large grounding systems. In this article, we extend the application of the rigorous model for large grounding systems in multilayered soil by applying a procedure that minimizes the number of direct computations of the SI using interpolation over a grid of a small number of sample points. We implement a three-dimensional interpolation scheme that adapts to the problem to minimize the interpolation grid, maintaining the accuracy of the rigorous approach. The developed model is applied for the analysis of transient voltages that might couple to secondary cables and disrupt the operation of connected equipment in case of lightning. The analysis shows that there are cases when the image theory-based models might underestimate the possibly harmful transient voltages. [ABSTRACT FROM AUTHOR]

This article proposes an improved analytical approach to the electromagnetic performance of a linear oscillatory actuator, considering the end and stacking effects of the outer and inner cores. A simplified analytical model is defined with several assumptions taking into account the end effect of the outer and inner core in the $z$ -axis direction. Maxwell’s equations, partial differential equations, and Fourier series are used to derive the general solution in each subdomain of the proposed model. By calculating the boundary conditions applied in the $r$ - and $z$ -directions, unknown coefficients of analytical solutions are derived. The electromagnetic performances are expressed mathematically from the derived analytical solutions. To increase the accuracy of the proposed analytical method, a stacking factor that considers manufacturability is applied to the calculation of the electromagnetic performances. The validity of the proposed analytical method is verified by comparing the results of 2-D and 3-D finite-element analyses and the experiment. [ABSTRACT FROM AUTHOR]

The flux-concentrating permanent-magnet (FCPM) machine with two V-shape magnet pieces in one stator pole has attracted considerable attention due to its excellent torque density and permanent magnet (PM) usage efficiency, whereas the torque ripple of the FCPM machine is usually high. This article aims to make a multiobjective optimization design for the FCPM machine. The optimization process is divided into three steps for different optimization objectives on two sets of geometric variables at different operation conditions. The simulated results show that the output torque of the optimized FCPM machine is increased significantly while the torque ripple has been decreased greatly. Finally, the open-circuit field distributions, the output torque, the torque-speed characteristics, and PM demagnetization of the optimized FCPM machine are investigated considering different PM shapes and PM temperature rise, which indicates that the optimized FCPM machine has favorable torque characteristics, speed range, and antidemagnetization abilities. [ABSTRACT FROM AUTHOR]

Emerging additive manufacturing methods facilitate the creation of enclosures with tailor-made shielding and scattering performance by using multiple conductive and dielectric layers. For a first analysis an elongated housing, with a cross-section small compared to the wavelength of the impinging electromagnetic field is replaced by an infinitely long multilayered cylinder. In a previous paper, we concluded that existing solutions of the Maxwell equations for this configuration are not accurate in calculating scattering. This also negatively impacts results for multilayer shielding. This article proposes a fast, time-harmonic formulation based on a combination of Bessel and Hankel functions as solution to the Helmholtz equation. Both electric and magnetic fields are considered and solutions are obtained independently for transversal and longitudinal source fields. These can be superpositioned to describe arbitrary source fields. The system of equations defined by the boundary conditions of the multilayer problem is solved via Gaussian elimination which can easily be automated with standard MATLAB or Octave functions. Results are compared to known approaches and applied to a dual-layer use case. The latter shows that shielding and scattering performance improves significantly with multiple layers compared to a single layer with equivalent thickness both for transversal and longitudinal fields. [ABSTRACT FROM AUTHOR]

A novel tubular single‐phase linear generator with an axially magnetized permanent magnets (PM) mover is proposed in this paper for the application of free‐piston engine, which is an alternative power generation system of next‐generation electric vehicle. The transient 3D with motion electromagnetic field finite element model is created to analyze the EMF and thrust force characteristics of the linear generator. A 1.4 kW prototype with the max stroke of 40 mm and the max thrust force of 1670 N is developed, and main performances of the prototype are tested and validated with the finite element simulation. The prototype generating efficiency of 84 and 91% can be obtained respectively when driving by the 35 and 50 Hz sinusoidal reciprocation motion. Compared with the existed moving coil linear generator with similar generating efficiency, the mass power density and the volumetric power density of the new linear generator increase by about 37 and 80%, respectively. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

• Decreases semiconductor switches in MB. • Reduces the energy absorbed by the arrester. • Limits and absorbs fault energy in a short time. • Reduce the rising rate and peak of the fault current. • Less voltage stress is imposed on the converters and power electronic switches. In general, the fault current in high-voltage direct current (HVDC) grids has two characteristics: the rapid increase and the lack of a zero-crossing point. Therefore, a large reactor is necessary to fulfill DC fault current limiting. But this can have disadvantages on the dynamics and stability of the HVDC grid. In this paper, the integration of an E-core DC reactor based on thyristors with a hybrid HVDC breaker (RTHCB) is suggested as a solution. The proposed model reduces the rising rate and peak of the fault current and protects the LCS through the primary inductance of the reactor. In RTHCB, several capacitors and thyristors are placed in parallel with the secondary winding of the reactor to control the gradual and soft placement of the large inductance in the path of the fault current. This integration reduces the electrical stresses caused by the sudden disconnection of conventional HCBs. Due to the presence of the capacitors, the energy absorbed by the arrester decreases. In addition, it decreases semiconductor switches and absorbs fault energy in a short time. After theoretical analysis, the RTHCB is modeled on the 3D space of the COMSOL Multiphysics. Finally, an MMC-HVDC grid has been simulated in the PSCAD/EMTDC to validate the performance of RTHCB. [ABSTRACT FROM AUTHOR]

The gradual transition from a reactive to a radiative regime is studied for leaky modes supported by multilayered planar open waveguides. The so-called leaky cutoff condition, i.e., the frequency for which the leaky phase constant $\beta $ equals the leaky attenuation constant $\alpha $ , originally introduced for microstrip lines and other printed structures, is investigated here with the aim of providing detailed information on the relative amount of reactive and radiative attenuation for leaky modes excited by finite sources and propagating as cylindrical waves along general planar waveguides. Analytical results are derived on the basis of a lossy parallel-plate-waveguide model and are validated through full-wave numerical simulations of 2-D leaky-wave structures based on grounded slabs covered with lossless or lossy partially reflecting surfaces (including, e.g., graphene layers) that can be treated as homogenized sheets. An analysis of the complex wave impedance of the considered leaky modes is also provided, in order to assess the frequency ranges where a good input matching can be expected for practical sources. In this regard, an ad hoc impedance matching network is designed and full-wave validated for a specific case to show that is indeed possible to achieve a good impedance matching below the cutoff in practical designs. [ABSTRACT FROM AUTHOR]