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With regard to the state-of-the-art technologies in the fields of applied superconductivity and electromagnetic devices, research and development highlights are presented. The recent progress and achievement described with principle and technical details include mainly i) applied superconducting materials; ii) superconducting magnets and their applications such as in ITER and Tokamaks; iii) high T c superconducting (HTS) magnetic levitation and applications; iv) HTS smart grids; v) superconducting and electromagnetic material modelling and characterization; and vi) advanced electromagnetic devices. The applied superconductivity technology and availability are especially focused and verified with the trend of development prospection.

High frequency magnetic-link (HFML) is widely used in medium/high voltage power electronic converters for various applications. In this paper, a 440 V, 100 kHz compact HFML is designed with ANSYS/Maxwell software environment where the amorphous material is used as the magnetic core. The HFML is analyzed with solid toroidal cores with various winding configurations. A comparison of the HFML is performed for both the conventional copper winding and superconducting winding. Yttrium barium copper oxide material-based superconductor tape is applied to obtain the maximum power of the HFML. In addition, suitable winding configuration is selected to ensure possible maximum electrical power transfer while minimizing the magnetic saturation in the core. Simulation results show the electrical parameters of the HFML along with its magnetic flux density and power. The proposed HFML design with distributed winding is validated experimentally with a small-scale prototype where it is found that the maximum power transfer capability is increased more than 48% than that of the conventional one.

This paper presents a modeling approach for estimating the vibration of power transformers based on a magnetostriction model and maxwell stress calculation. The magnetostriction model, accounting for the dynamic hysteresis behavior, is constructed by combining the Becker-Doring crystal magnetostriction model and J-A dynamic hysteresis model. By incorporating the proposed model into the finite-element method (FEM), both the Maxwell stress and the magnetostriction force in each mesh element can be readily obtained simultaneously. To verify the calculation method, the vibration of a three-phase transformer prototype is measured and compared with simulated results. It demonstrated that the proposed method is accurate enough to predict the vibration of power transformers.

© 2002-2011 IEEE. The detent force caused by the cogging effect and end effect will seriously affect the operation of a tubular flux-switching permanent magnet motor (TFSPMM). This paper proposes a method to weaken the end effect and minimize the detent force and force ripple of a TFSPMM using un-equal width stator slots. To overcome the problem of excessive calculation, the Taguchi method is performed to find the optimal combination of stators with unequal slot width. The proposed method can significantly decrease the detent force and force ripple and keep the thrust force basically unchanged. The permanent magnet flux linkage, detent force and electromagnetic force are calculated by the two dimensional (2D) finite element method (FEM).

With the development of advanced soft magnetic materials of high-saturation flux density and low specific core loss and semiconductor power devices, the high-frequency transformer (HFT) has received significant attention in recent years for its widespread emerging applications. The optimal design of high-power-density HFTs for high-performance energy conversion systems is, however, a multiphasic problem that needs special considerations on various aspects such as core material selection, minimization of parasitic components, and thermal management. This paper presents a comprehensive review on advancement of soft magnetic materials for high-power-density magnetic devices and advanced technologies for characterizations and optimal design of HFTs. The future research and development trends are also discussed.

To avoid overheating of a totally enclosed high-speed permanent magnet synchronous machine (PMSM) with an amorphous alloy core, this paper proposes a hybrid cooling system with both radial and axial vents to maintain the temperature rise below the rated value. The analytical models of cooling ability and frictional loss generated in the rotor ducts are derived in relation to the cooling structure parameters. The sensitivity of each parameter to the cooling effect is researched, and the parameter scopes are then determined. A coupled fluidic-thermal model based on the cell method is developed to predict numerically the temperature distribution to check the effectiveness of the cooling system. By analyzing the influences of the numbers and sizes of the cooling ducts on the efficient cooling air quantity and temperature, the feasible parameters that yield reasonable temperature distribution can be determined. The theoretical results are confirmed by experimental test results on a 15-kW 30 000-r/min PMSM prototype.

If the batteries are charged by clean renewable energy sources, electric vehicles (EVs) can have zero gas emission, contributing greatly toward the preservation of the green environment. In a smart micro-grid, EVs together with other distributed energy storage units can be used to supply electricity to the loads during the peak hours so as to minimize the effects of the load shedding and improve the quality of electricity. To achieve these goals, an isolated hybrid multi-port converter is required to control the power flows and balance the energy among renewable energy sources, EVs, and the grid. In this paper, a new isolated multi-port converter is proposed, which can control the power flow in multiple directions. The converter is modeled in the matlab/Simulink software environment and this validates the technology with a laboratory prototype test platform. The modeling, implementation, and results are discussed comprehensively.

This paper presents an amorphous alloy magnetic-bus-based neutral point clamped (NPC) converter for grid-connected renewable generation systems. In the proposed system, the amorphous alloy high-frequency high-power density multi-winding magnetic bus generates balanced dc supplies for the five-level (5L) NPC converter for high-quality power conversion. Compared to the traditional NPC converter topologies, the proposed magnetic-bus-based architecture does not require any control circuit for voltage balancing of the series connected capacitors. The magnetic bus inherently overcomes galvanic isolation issues and may reduce the size of the boosting inductor. In this paper, a finite control set model predictive control algorithm is derived to control the grid-connected 5L-NPC inverter for multilevel voltage synthesizing, while achieving the user-defined active and reactive power values. To verify the proposed concept, a simulation model is developed and analyzed in MATLAB/Simulink environment. To validate the technology, a scale d-down prototype test platform is developed in the laboratory with silicon carbide switching devices, which achieves high blocking voltage, low power dissipation, high switching frequency, and high-temperature operation. Based on the simulation and the experimental results, it is expected that the proposed converter will have a great potential for widespread application in renewable generation systems including superconducting generator-based wind turbines.

© 2002-2011 IEEE. This paper presents a novel axial field flux switching memory (AFFSM) machine, which integrates series permanent magnet (SPM) and an additional dc field winding for improving the flux regulation capability. The configuration and the operation principle of the SPM-AFFSM machine are presented. The design considerations for the SPM and the dc field winding are discussed. The voltage regulation capability and torque-speed characteristics of the SPM-AFFSM machine are investigated by 3-D FEA. Finally, a prototype is developed for experimental verification. The measured results verify structural validity and the finite-element predictions.

© 2002-2011 IEEE. This paper investigates the efficient robust design and optimization of a high-Temperature superconducting (HTS) linear synchronous motor by using the Taguchi parameter design approach. The manufacturing tolerances of the HTS magnets, primary iron core and the air gap are considered in the robust design to ensure that the optimal design is less sensitive to these uncertainties. To overcome the disadvantages of the conventional Taguchi parameter design approach, a sequential Taguchi robust optimization method is presented for improvement of the motor performance and manufacturing quality. The proposed method is efficient because it holds the advantages of both Taguchi method and sequential optimization strategy. It can significantly increase the average thrust and decrease the thrust ripple of the investigated HTS linear synchronous motor.

© 2016 IEEE. Superconducting magnetic energy storage (SMES) systems with different superconducting materials are attracting great attentions and funding from the governments around the world because they are promising large-scale energy storage devices for future smart grid. Due to the high cost of SMES, its manufacturing quality and operation reliability have to be investigated in the design optimization stage. This paper presents a robust design optimization method to solve this issue based on a benchmark problem, TEAM problem 22. The proposed method is based on a technique called design for Six Sigma. Meanwhile, a three-level optimization framework is employed to reduce the computation cost of a finite-element analysis due to high-dimensional design space and Monte-Carlo analysis. As shown, the manufacturing reliability and quality of the investigated SMES after robust optimization have been increased greatly.

As the critical barriers to advanced high-temperature superconducting (HTS) device technologies are overcome, practical HTS devices and systems have been enabled and become available for commercial application. In identifying the applicability of various HTS devices, their operation principles, characteristics, performance, and efficiency are fundamental. Consequently, the corresponding verification of a wide range of HTS devices, especially the HTS power devices and their system technologies, has been comprehensively carried out, and the analytical results are presented in detail towards their practical applications.

In the fabrication of soft magnetic composite materials, the iron powder particles are submitted to a high-pressure compaction process that should be considered in the modeling of magnetic hysteresis. This paper introduces a novel approach for modeling the stress-dependent magnetic hysteresis, based on the Stoner–Wohlfarth (S–W) model. Moreover, for determining the S–W particle equilibrium orientation directly, an extended S–W astroid method, which considering the stress effect, is presented. To verify this presented model, the magnetic hysteresis phenomenon of SOMALOY 500 are measured and simulated. The comparison between the two results shows that this model is feasible and effective, which can be applied to practical engineering.

In this paper, the extended finite-element method (XFEM) is used for modeling weak discontinuities in electric fields. For a weak discontinuous domain, the first-order derivative of the electric potential is discontinuous although the electric potential, degree of freedom, is continuous. In order to improve the approximation space of the conventional finite element method (CFEM), the enrichment function of the key of XFEM is used to model weak discontinuous solutions independent of the mesh. Interfaces among different materials can be described well by using the level set method. Numerical examples applied to the parallel plate electrodes in 1-D and the insulating oil with a bubble in 2-D static electric field involving error analysis, computational time, and electric field computations are provided to demonstrate the utility of XFEM in electric fields.

This paper proposes a method to minimize the cogging torque of a permanent-magnet transverse flux machine (PMTFM) with soft-magnetic-composite cores, using the shifted stator disks and unequal stator teeth pairing. Fourier analysis is performed to find the major cogging torque component so as to reduce it by shifting the stator disks. The unequal stator teeth pairing technique that is traditionally used in the radial and axial flux machines is employed to reduce the cogging torque of PMTFMs in this paper. Three different configurations are studied. The cogging torque and the electromagnetic torque are calculated by the three-dimensional finite-element method and verified by the experiment results.

The design considerations of permanent-magnet transverse flux machines (PMTFMs) with soft magnetic composite (SMC) cores are investigated in this paper. A simplified torque equation of the PMTFMs is deduced first. It is shown that the torque coefficient is directly related to the air-gap flux density, the number of pole pairs, and the stator slot width, etc. To accurately illustrate the influences of these parameters on motor performance, electromagnetic and mechanical analyses are completed by using the 3-D finite element method. For the laboratory prototype, SMC cores can be manufactured by two methods, namely, wire cutting and mould pressing. It is found that wire cutting method deteriorates the magnetic properties of SMC cores and lowers the machine performance. The performance predictions of the PMTFMs are compared for these two methods in this paper. The calculation results are verified by the experimental results.

© 2015 IEEE. Recent advances in solid-state semiconductors and magnetic materials have provided the impetus for high-frequency magnetic-link-based modular medium-voltage power conversion systems, which would be a possible solution to reduce further the weight and volume of superconducting generator-based wind generation systems. To verify this new concept, in this paper, a laboratory prototype of 5 kVA high-frequency magnetic-link modular power conversion system is developed for a scaled down 1.2 kV grid application. The design and implementation of the prototyping, test platform, and the experimental results are analyzed and discussed. It is expected that the proposed new technology will have great potential for superconducting generator-based wind farm applications.

A variety of storage technologies for transmission grid and electric vehicle applications has been gaining importance in the last few years. The supercapacitor is one of the most viable energy storage devices. In this paper, a high-specific-capacitance supercapacitor with vanadium oxide nanoribbon electrode was fabricated. Vanadium oxide nanoribbon was synthesized by a facile and effective hydrothermal treatment with controlling the condensation speeds of precursors in the solution along the 〈010〉, 〈010〉, and 〈010〉 directions. The synthesis involved dissolution of V2O5 into H2O2, and investigation of the precursor weight ratio and the hydrothermal time. The product was characterized by using scanning electron microscopy, transmission electron microscope and X-ray. The electrochemical properties of the material as the electrode of electrochemical capacitor were evaluated by cyclic voltammetry in a three electrode system consisting of a saturated calomel electrode as reference electrode, platinum as a counter electrode and the active material as the working electrode. As far as we know, it is for the first time to report the fabrication of vanadium oxide nanoribbon by using the hydrothermal method. The prepared nanoribbon structure possesses relative short width and significant length. The narrow nanoribbon with ultra-length optimizes the ion diffusion path thereby enhancing the specific capacitance. A high capacitance of 453 F/g was obtained at the scan rate of 2 mV/s in 2 M NaCl electrolyte, and it still maintained a high capacitance of 201 F/g at a higher scan rate of 50 mV/s. And the nanoribbon exhibits faster ion propagation and better conductivity than the nanotube as revealed by the immediate current response to the potentials added on the electrode. The electrochemical performances of the vanadium oxide were found to strongly depend on the nanostructures and electrolytes.

Three-dimensional magnetic properties of the soft magnetic materials should be considered and comprehensively analyzed in electrical engineering, compared with the traditional 1-D and 2-D testing method. A novel 3-D magnetic properties measurement structure with symmetrical “C-type” cores has been designed and modeled. To guarantee the experimental precision and accurately analyze the 3-D magnetic properties of the soft magnetic materials, especially for laminated silicon steel, a symmetrical 3-D magnetic flux path in the magnetization structure fit for given dimension of the cubic specimen has been calculated and modeled. Magnetic flux in each direction has been homogenized and concentrated on the top of the core poles by means of finite element analysis. Therefore, magnetic properties measurement in each direction of the specimen can become practical.

High temperature superconductors (HTSs) can produce a strong magnetic levitation force with self-stabilizing feature and hence have attracted much attention for applications in maglev transportation systems. For the linear motion of transportation, a linear drive is an obvious advantage. This paper presents the design and analysis of a permanent magnet (PM) linear synchronous motor for driving a small-scale prototype vehicle with PM-HTS bulks used for the levitation. The linear motor consists of PMs on the vehicle sides and stator windings in the slots of side tracks. The three phase windings are supplied by a 3-phase inverter, and are controlled with a brushless DC control scheme. Analysis and calculation details of magnetic fields and driving force about the motor prototype are presented.

High-temperature superconductors (HTSs) including HTS bulks and tapes have potential applications in linear motion drive and magnetic levitation/suspension systems generating substantial advantages over conventional ones. When an HTS linear motor is integrated with an HTS magnetic suspension subsystem, it can inherit both merits of HTS linear motion drive and HTS magnetic suspension simultaneously and can be applied into various fields, such as the maglev and electromagnetic aircraft launch systems (EMALSs). Based on different HTS aspects and arrangements, three modes of HTS linear synchronous motor (HTSLSM) integrated with HTS magnetic suspension subsystems have been proposed in this paper. To verify the modes for the design of a practical HTSLSM, the structural features of these systems are described, the magnetization characteristics to obtain HTS bulk magnets, the trapped-field attenuation characteristics of the HTS bulk magnet exposed to external traveling field, and the magnetic field distribution characteristics for different permanent-magnet guideways have been studied with experimental verification. Based on the study, a demonstration prototype of a single-sided HTSLSM integrated with HTS magnetic suspension subsystems has been developed. Its performance and thrust characteristics have been obtained by experimental measurements and compared with theoretical results. With regard to practical applications, two modes of double-sided HTSLSM integrated with HTS magnetic suspension subsystems have been designed for the maglev and EMALS, respectively, and then, the 2-D finite-element-analysis models for the HTSLSMs were built to analyze their performance characteristics. The comprehensive simulations and experimental results constitute a framework for the structural and electromagnetic design of the HTSLSM integrated with HTS magnetic suspension for practical applications.