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The recent development of micro-fabrication technologies has provided new methods for researchers to design and fabricate micro metal coils, which will allow the coils to be smaller, lighter, and have higher performance than traditional coils. As functional components of electromagnetic equipment, micro metal coils are widely used in micro-transformers, solenoid valves, relays, electromagnetic energy collection systems, and flexible wearable devices. Due to the high integration of components and the requirements of miniaturization, the preparation of micro metal coils has received increasing levels of attention. This paper discusses the typical structural types of micro metal coils, which are mainly divided into planar coils and three-dimensional coils, and the characteristics of the different structures of coils. The specific preparation materials are also summarized, which provides a reference for the preparation process of micro metal coils, including the macro-fabrication method, MEMS (Micro-Electro-Mechanical System) processing technology, the printing process, and other manufacturing technologies. Finally, perspectives on the remaining challenges and open opportunities are provided to help with future research, the development of the Internet of Things (IoTs), and engineering applications. [ABSTRACT FROM AUTHOR]

This paper is mainly devoted to the three-dimension calculation of the electric and magnetic fields in the simplified arc chamber of low-voltage circuit breakers. Coupled with the plasma flow field, the electric potential and current density in arc plasma are calculated according to the electric conductivity, which is mainly decided by the temperature. Based on the potential vector method, the magnetic flux density and the Lorentz force under the effect of the ferromagnetic splitter plates are obtained. Both the stationary and transient results of the calculation are discussed in detail. Index Terms--Arc plasma, circuit breaker, temperature.

A two-dimensional flux-flow model is constructed to investigate the electromagnetic characteristics of a melt cast process BSCCO-2212 tube. Solving the flux-flow equilibrium equation with numerical method, we obtain the distributions of the current density, the flux density, and the flux-flow resistivity. The effect of inner radii on the critical current is also investigated. Based on the characteristic of the average flux-flow resistivity, we simulate the quenching process of the tube by ANSYS. The calculation results are significant for optimization and safety design of the current lead. Index Terms--Electromagnetic coupling, flux-flow resistivity, superconducting materials, thermal-electric coupling.

An electromagnetic rail launcher (ERL) is essentially a high-speed linear motor, which can accelerate projectiles from milligrams to several kilograms and the velocities of which can reach more than several kilometers per second. In this article, the dynamic electromechanical characteristics of an ERL with the cross-section of plane, convex, and concave rails under different conditions of frictional coefficient and channel cooling are investigated. The kinematic characteristics of armatures and the stress distribution of three types of rails are compared. The mathematical relation between the frictional coefficient, the sliding time, and the armature speed in an ERL with three types of rails is obtained. The equations for the frictional coefficient, the sliding time, and the displacement of armature in an ERL with three types of rails are obtained. Under the same frictional coefficient condition, the velocity and displacement of armature in an ERL with a convex rail are the largest. The peak stress in a plane rail during one shot period is the greatest. In light of obtaining a higher armature velocity and moderate stress in a rail, the ERL with convex rails is the best one. [ABSTRACT FROM AUTHOR]

Thermal characteristics were studied for the cross section of plane, convex, and concave rails by channel cooling and surface/channel cooling at repetition rate: 10 and 20 shots/min, respectively. The simulations were all done for 10 sequential shots. During 10 shots time, the peak temperature in three type rails by two cooling approaches is much lower than melting point of rail. Peak temperature in concave rail by two cooling conditions is the highest at the same moment within 10 shots time under identical conditions. Maximal temperature in three type rails by two cooling methods, all increases exponentially with time. In light of obtaining lower peak temperature in rail, convex rail is better than plane and concave rail. In terms of avoiding ablation and gouging, surface/channel cooling is better than channel cooling. [ABSTRACT FROM AUTHOR]

For the electromagnetic rail launcher, the parameters variation has obvious effect on the dynamic performance and efficiency. This paper constructs the system simulation model of the electromagnetic rail launcher by using of Simulink software, and then analyzes the influences on the system dynamic performance for main devices. Based on the parameters and large current condition, the launching efficiency model is constructed, and the energy distribution characteristics are obtained. The loss of rail, armature, and feeder equipment is 38.7%, and the loss of arc extinguishing equipment is about 4.76%, so the heat loss is about 43.46% of total loss. When considering that the other loss is 33.37%, the system energy efficiency is 23.17%. Based on the design of the small prototype, the energy loss characteristics of the full prototype in launch rail and its temperature features are discussed in detail. The peak temperature is 276 °C after 11 continuous shots with converting coefficient being 5000 W/( \textm^2\cdot \text K ), and it can decrease 58 °C if the better convection boundary condition is achieved, which means the rail can meet the requirement of the thermal management. [ABSTRACT FROM PUBLISHER]

This study presents a novel switched reluctance machine (SRM) with modular E‐core stators and multi‐layer common rotors for high reliability applications. The stator is composed of six independent modular E‐cores with the windings wound around the yoke of the E‐cores. The rotor consists of three magnetically independent common rotors which are place in the same shaft without any angular shift. The equivalent magnetic circuit (EMC) models of this new SRM at the aligned and unaligned positions are described. To evaluate the motor performance, two types of analysis, namely, approximate simplified two‐dimensional (2D) model and 3D model finite‐element analysis (FEA) have been utilised. The 2D FEA static and dynamic results are compared with 3D FEA results. Furthermore, comparisons between the novel modular SRM and a conventional 6/4 SRM are made. Finally, a prototype of this modular SRM has been fabricated and tested in the laboratory. Comparison between FEA and EMC analysis for flux linkage are made and compared with measured characteristics. The simulated and measured phase currents and average torque are also presented and compared to verify the analytical and simulation results. [ABSTRACT FROM AUTHOR]

This paper presents comparative studies of magnetic characteristics and dynamic performances for two mutually coupled dual-channel switched reluctance machines (DCSRMs) with the same properties and different winding connections. A 2D/3D finite element method (FEM) is used to analyze the magnetic field distributions and calculate the static inductance and torque characteristics of these two DCSRMs. The different static magnetic characteristics, details of mathematical models and dynamic performances prediction at transient and steady states for these two DCSRMs under single- and dual-channel operation modes are presented and compared. Finally, an experimental setup for two high speed 12/8-pole DCSRMs with different winding connections is built. The experimental results of these two DCSRMs such as phase current, average torque, copper loss, iron loss and efficiency under different operation modes are presented and compared to verify the analytical and simulation results. [ABSTRACT FROM PUBLISHER]

This study proposes an improved decoupled model of mutually coupled dual‐channel switched reluctance machine (DCSRM) based on the equivalent inductance and flux linkage characteristics that consider magnetic saturation in dual‐channel operation (DCO) mode. A three‐dimensional finite‐element analysis (FEA) is used to calculate the static phase equivalent inductance of DCSRM for the simultaneous two‐phase excitation with consideration of saturation. And an indirect experimental test is performed to measure the equivalent flux linkage under the simultaneous two‐phase excitation and compared with the FEA results. In this improved decoupled model, the phase equivalent inductances and flux linkages in each channel are independent to each other and separately expressed as a function of rotor position and their own phase current. The static magnetic characteristics, details of modelling procedure and performances prediction for the DCSRM under DCO mode without and with consideration of saturation are compared. Finally, an experimental set‐up for a 12/8 DCSRM drive system based on dSPACE is built and the simulation and experimental results are compared, which verifies high accuracy of this improved modelling method. [ABSTRACT FROM AUTHOR]

The following article published in IET Electric Power Applications, Ding, Wen; Liu, Ling: Lou, Jianyong: 'Design and control of a high‐speed switched reluctance machine with conical magnetic bearings for aircraft application', IET IET Electric Power Applications, 2013, Volume 7, Issue 3, doi: 10.1049/iet‐epa.2012.0319 has been retracted. Following a rigorous and considered review of this content, this paper has been found to be in violation of the IET's Policy in Relation to Plagiarism, Infringement of Copyright and Infringement of Moral Rights and Submission to Multiple Publications. [ABSTRACT FROM AUTHOR]

The selective passively compensated pulsed alternator has wide applications in military and civil areas such as power source for electromagnetic launch, electrothermal chemical gun and plasma sprayed coating. It can produce wide range of current waveforms realized by shorted compensating windings. In this paper, two cases of winding arrangements and their corresponding circuit models are presented to further discuss on the power waveform regulations. The effects of the phase angles between different windings and the switching time on the pulsed power are presented in this paper as well. The results indicate that the output power waveform is possible to be regulated flexibly especially through the new winding arrangements proposed in this paper. This work may extend the applications of selective passively compensated pulsed alternator where different output waveforms are required. [ABSTRACT FROM PUBLISHER]