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The conventional combined atomization smelting process was improved and optimized in this paper, the powder morphology was improved by enhancing the effect of the primary atomization stage and prolonging the time of droplet spheroidization. Spherical powders with different particle sizes were prepared by the improved combination atomization process and compared with those prepared by the conventional combination atomization. The results show that the powders prepared by the improved atomization process show the characteristics as good morphology, small specific surface area, and low oxygen content. At the same time, the permeability is lower than that of the conventional atomized powders, but the DC bias ability of magnetic core is significantly improved, and the hysteresis loss and eddy current loss are significantly reduced.

With the global trend of carbon reduction, high-speed maglevs are going to use a large percentage of the electricity generated from renewable energy. However, the fluctuating characteristics of renewable energy can cause voltage disturbance in the traction power system, but high-speed maglevs have high requirements for power quality. This paper presents a novel scheme of a high-speed maglev power system using superconducting magnetic energy storage (SMES) and distributed renewable energy. It aims to solve the voltage sag caused by renewable energy and achieve smooth power interaction between the traction power system and maglevs. The working principle of the SMES power compensation system for topology and the control strategy were analyzed. A maglev train traction power supply model was established, and the results show that SMES effectively alleviated voltage sag, responded rapidly to the power demand during maglev acceleration and braking, and maintained voltage stability. In our case study of a 10 MW high-speed maglev traction power system, the SMES system could output/absorb power to compensate for sudden changes within 10 ms, stabilizing the DC bus voltage with fluctuations of less than 0.8%. Overall, the novel SMES power compensation system is expected to become a promising solution for high-speed maglevs to overcome the power quality issues from renewable energy. [ABSTRACT FROM AUTHOR]

Due to the ever-increasing switching speeds of wide band gap (WBG) devices, the high-frequency behavior of magnetic components, such as medium-frequency transformers, is becoming increasingly significant. To describe this complex high-frequency behavior, large multiconductor networks are commonly employed. The frequency-dependent parameters of these networks are typically represented as matrices. However, accurately calculating these matrices often necessitates time-consuming finite element analysis (FEA), which significantly limits the investigation of various geometries within a practical timeframe. This paper addresses this problem by proposing a model based on analytical formulations for the frequency-dependent resistance and inductance matrices of transformers with litz wire windings. The model is experimentally verified showing good agreement to the measurements over a wide frequency range. Compared to FEA only a marginal deviation of less than 2% is noticeable, whereas the calculation is more than 200 times faster.

In this paper, a streamline display method for magnetic flux density and magnetic field strength vectors in a three‐phase induction motor model core is presented, and the relationship between streamlines and magnetic properties is investigated. It is possible to visualize the vector magnetic properties distribution by representing the magnetic flux density and the magnetic field strength vector with the streamlines. In addition, the time variation of the streamlines of the magnetic flux density and magnetic field strength vectors, and magnetic energy was compared. It was clear that the magnetic energy did not necessarily increase in the areas where the magnetic flux density and magnetic field strength increased because these vectors have the spatial phase difference. [ABSTRACT FROM AUTHOR]

New energy materials refer to the key materials used in the transformation and utilization of new energy and the development of new energy technologies. The soft magnetic has high saturation magnetic induction intensity, good high-frequency magnetic properties, low loss and low cost, and is widely used. In this paper, according to the high magnetic properties of soft magnetic materials, the static and dynamic performance of the electromagnetic actuator under the new magnetic steel structure is studied. Based on the finite element method, the AC / DC module in COMSOL is used to study and simulate the performance of electromagnetic actuator. The relationship between electromagnetic actuator output and current and frequency under steady state is studied, and the influence of surface skin effect is simulated. The static linearity of electromagnetic actuator is observed by simulation in time domain; Simulation analysis of linearity in steady state. The relationship between the output of the actuator and the current and frequency is obtained by the simulated two-dimensional line diagram, and the distribution of the skin effect inside the electromagnetic actuator is obtained by the surface diagram. The static working simulation in time domain obtains the static linearity, and the simulation in steady state obtains the linearity in working state. The output performance of the electromagnetic actuator under the new magnetic steel structure is improved, with an increase rate of 47.3%, and its skin effect is evenly distributed. The static linearity increases by 63% and the dynamic linearity increases on average. According to the results of the research and simulation, it has a theoretical reference value for the promotion and application of magnetic energy, as well as the use of electromagnetic actuators for motor structure optimization and efficient matching.

In this paper, we study a quasilinear coupled magneto-quasistatic model from a systems theoretic perspective. First, by taking the injected voltages as input and the associated currents as output, we prove that the magneto-quasistatic system is passive. Moreover, by defining suitable Dirac and resistive structures, we show that it admits a representation as a port-Hamiltonian system. Thereafter, we consider dependence of the solution on initial and input data. We show that the current and the magnetic vector potential can be estimated by means of the initial magnetic vector potential and the voltage. We also analyse the free dynamics of the system and study the asymptotic behavior of the solutions for $ t\to\infty $. [ABSTRACT FROM AUTHOR]

A nano-SiO2 inorganic insulation layer was coated on the surface of FeSi magnetic powder via in situ fluidised vapour deposition. The surface was then coated with organosilicon resin to form an inorganic/organic double-insulating layer. Post-forming and annealing, a ferrosilicon magnetic powder core was prepared. The effects of organosilicon resin content and pressing pressure on the permeability and loss of the ferrosilicon magnetic core were studied. When the ferrosilicon magnetic core was doubly insulated with SiO2/silicone resin, the silicone resin content increased, the insulation coating gradually thickens, and the saturation magnetic-induction intensity of the magnet gradually decreases; the density and effective permeability showed a trend of increasing first and then decreasing. Increasing the forming pressure can reduce the loss of the core, thereby improving the performance of the core and increasing the permeability without damaging the double-cladding layer. In the powder with the optimised silicone resin content (1.5 wt.%), the magnetic properties of the magnetic core were maximised after preparation at 1500 MPa followed by heat treatment at 773 K. The saturation magnetisation was 187.5 emu/g and the resistivity and permeability reached 10.5 Ω·cm and 49.6, respectively, at 100 mT and 50 kHz. The total loss was 905 mW/cm3. [ABSTRACT FROM AUTHOR]

Al-Si-Mg-Cu-Ni alloy is widely used in the manufacture of high-performance car engine parts. Coarse, dendritic α-Al and large primary Si are common in Al-Si-Mg-Cu-Ni alloy DC casting billet, which is harmful to the performance of the final product. In this paper, a pulsed magnetic field melt treatment technique was applied to the melt in the launder of a DC casting platform to modify the α-Al and primary Si in the billet. A transient numerical model was established to analyze the electromagnetic field, flow field and temperature field in the melt during the pulsed magnetic field treatment. The effect of the magnetic energy on the clusters in the melt was analyzed. We found that during the pulsed magnetic field melt treatment, the number of clusters close to the critical size was increased due to the cluster formation work being reduced by the magnetic energy, which facilitated nucleation and refined the solidification structure. Furthermore, the flow velocity increased, and temperature homogenized in the melt during the pulsed magnetic field melt treatment, which benefitted the clusters close to the critical size distributed and maintained in the melt uniformly. The experimental results show that the α-Al and primary Si were small and homogeneous following the pulsed magnetic field melt treatment. The size of α-Al and primary Si was reduced by 25.6–44.4% and 32.2–54.1%, respectively, in the billet center compared to the conventional process. [ABSTRACT FROM AUTHOR]

A nano-SiO2 inorganic insulation layer was coated on the surface of FeSi magnetic powder via in situ fluidised vapour deposition. The surface was then coated with organosilicon resin to form an inorganic/organic double-insulating layer. Post-forming and annealing, a ferrosilicon magnetic powder core was prepared. The effects of organosilicon resin content and pressing pressure on the permeability and loss of the ferrosilicon magnetic core were studied. When the ferrosilicon magnetic core was doubly insulated with SiO2/silicone resin, the silicone resin content increased, the insulation coating gradually thickens, and the saturation magnetic-induction intensity of the magnet gradually decreases; the density and effective permeability showed a trend of increasing first and then decreasing. Increasing the forming pressure can reduce the loss of the core, thereby improving the performance of the core and increasing the permeability without damaging the double-cladding layer. In the powder with the optimised silicone resin content (1.5 wt.%), the magnetic properties of the magnetic core were maximised after preparation at 1500 MPa followed by heat treatment at 773 K. The saturation magnetisation was 187.5 emu/g and the resistivity and permeability reached 10.5 Ω·cm and 49.6, respectively, at 100 mT and 50 kHz. The total loss was 905 mW/cm3.

Triboelectric nanogenerators (TENGs) are attractive in powering sensors for smart power grids. Herein, a TENG based on a rotational magnetic ball is presented to harvest the magnetic energy of transmission lines. The magnetic ball rolls in a spherical shell under the alternating magnetic field generated by the transmission line. The centrifugal force produced during the rotation is used to drive a TENG unit (ten times the weight of the magnetic ball and shell) to generate electricity with the assistance of coil springs. The device can maintain the stability of the output performance under high current shocks; meanwhile, the open‐circuit voltage, output power, and operating frequency of a single TENG unit can reach 1.5 kV, 6.67 mW, and 20 Hz, respectively. Furthermore, a wireless alarm system for monitoring the temperature and dip angle of transmission lines is successfully driven by this device. This work demonstrates an efficient and nontraditional strategy for harvesting magnetic energy through TENG, which is applied to power‐distributed and self‐powered sensors for monitoring transmission lines. [ABSTRACT FROM AUTHOR]

Energy is a natural demand and engineers are trying to come up with new ways to generate energy. Solar energy has made a big difference in the last decade. Now the struggle is to generate free energy through the use of magnetic attraction and repulsion. During studies on single magnets it is proven that 100 per cent free radicals cannot be produced although 40-60 per cent can be produced considering the data system with which the energy generated by the use of generator. The experiment was performed and after many refinements and experiments resulted in a experiment. [ABSTRACT FROM AUTHOR]

It is well known that the magnetic helicity is not a single invariant in ideal magnetohydrodynamics. We study the problem of whether the exponent of the slope of the turbulent spectrum of magnetic energy can be explained. An affirmative answer is obtained under the assumption that the quasiperiodic magnetic field is freely distributed over the scale. The answer is based on the use of the asymptotic Hopf invariant and the -invariant numerical measure of knottedness of magnetic lines . [ABSTRACT FROM AUTHOR]

This article presents a new method for generating low-frequency electromagnetic waves for navigation and communication in challenging environments, such as underwater and underground. The key concept is to disturb the magnetic energy stored around a permanent magnet in a time-variant fashion. The magnetic reluctance of the medium around the permanent magnet is modulated to alter the magnetic flux intensity and direction (disturb the stored energy) in order to achieve this goal. The nonlinear properties of the surrounding magnetic material are a critical phenomenon for efficient and effective modulation. Since the proposed way of generating the electromagnetic field is not based on a second-order system (resonant structure), the bandwidth of any modulation schema is not limited to the overall system quality factor. A transmitter is prototyped as a proof of concept, and the generated field is measured. Compared with the rotating magnet, the prototyped transmitter can modulate up to 50% of the permanent magnet’s stored energy with much lower power consumption. [ABSTRACT FROM AUTHOR]

Al-Si-Mg-Cu-Ni alloy is widely used in the manufacture of high-performance car engine parts. Coarse, dendritic α-Al and large primary Si are common in Al-Si-Mg-Cu-Ni alloy DC casting billet, which is harmful to the performance of the final product. In this paper, a pulsed magnetic field melt treatment technique was applied to the melt in the launder of a DC casting platform to modify the α-Al and primary Si in the billet. A transient numerical model was established to analyze the electromagnetic field, flow field and temperature field in the melt during the pulsed magnetic field treatment. The effect of the magnetic energy on the clusters in the melt was analyzed. We found that during the pulsed magnetic field melt treatment, the number of clusters close to the critical size was increased due to the cluster formation work being reduced by the magnetic energy, which facilitated nucleation and refined the solidification structure. Furthermore, the flow velocity increased, and temperature homogenized in the melt during the pulsed magnetic field melt treatment, which benefitted the clusters close to the critical size distributed and maintained in the melt uniformly. The experimental results show that the α-Al and primary Si were small and homogeneous following the pulsed magnetic field melt treatment. The size of α-Al and primary Si was reduced by 25.6–44.4% and 32.2–54.1%, respectively, in the billet center compared to the conventional process.

This study describes a method for calculation of transformer short‐circuit voltage using conformal mappings, which map the transformer longitudinal and transverse cross‐section geometry to a unit disk where an analytical solution for magnetic flux density is obtained and then transformed back to the original domain. The short‐circuit voltage is calculated by the integration of the magnetic energy of the leakage field in the windings and the space around windings, excluding the core. This method takes into account windings of different height, the fringing effect at the ends of the windings and any relative position of windings located on the same or different limbs. Also, it is possible to calculate the short‐circuit voltage for multiple windings. [ABSTRACT FROM AUTHOR]

This study proposes a new structure of hybrid cascade coupled-inductor high step-up (HCCIHSU) DC/DC converter for renewable energy sources. The proposed topology can provide an ultra-high voltage gain under continuous input current and low voltage stress on semiconductor devices. This converter is a hybrid cascade connection of the boost and buck–boost converters. The HCCIHSU utilises a coupled-inductor (CI) and a voltage multiplier (VM) cell to enhance the voltage gain ratio as a semi-quadratic function. The magnetic energy of the leakage inductor of the CI is recycled to the VM capacitors that reduce the component voltage stress and improve the converter voltage gain. Additionally, the voltage stress on the main power switch is clamped by two passive clamp capacitors. Due to the very high voltage conversion ratio at a reduced turn's ratio, the maximum voltage stresses on the switches and diodes are significantly alleviated, which further improve the efficiency. In this study, detailed steady-state analysis and comparisons with other related converters are provided. Finally, a 160 W/200 V laboratory prototype is built with 24 V input voltage at a switching frequency of 50 kHz to verify the performance of the proposed converter. [ABSTRACT FROM AUTHOR]

A vibration energy harvester (VEH) converts the kinetic energy of a moving source into electrical energy. In this article, we consider a 1-D electromagnetic vibration energy harvester (1-D EMVEH) that consists of three coaxial cylindrical permanent magnets enclosed in a tube such that the middle magnet is levitating. The resulting movement of the middle magnet can then induce an electromotive force (EMF) in one or more surrounding coils. Using an analytical model, we derive expressions for the 1-D-EMVEHs characteristic frequency and output power by using the Fourier space approach. First, the magnetostatic energy of the system as a function of the position of the levitating magnet is calculated. Its spatial gradient gives the force acting on a magnet, which drives its dynamics. Next, more accurate magnetic flux and EMF expressions are obtained. The results are compared with experimental measurements, revealing an excellent agreement. [ABSTRACT FROM AUTHOR]

Since surface finishing is a necessary process to meet various requirements in a manufacturing stage, numerous finishing method have been studied to improve the surface integrity. In particular, use of magnetic energy has been developed due to benefits for complex surface. However, it is an immature technique for non-ferrous materials due to low permeability, and also it is the time-consuming process for large area, which is caused be low finishing rate. To overcome drawbacks of magnetic finishing methods, this study suggests a magnetic pin polishing (MPP) process affected by combined magnetic and kinetic energy. According to analysis of experimentation, surface roughness improved due to pin's dynamic motion which is generated by magnetic force and torque in presence of the magnetic field. [ABSTRACT FROM AUTHOR]

The mean magnetic field equation describes the process of generating a magnetic field on a large scale as a result the EMF arising on a small scale. We consider the case where the large-scale magnetic field is also random and determine the density function of magnetic helicity. This function is invariant under gauge transformations of the magnetic vector potential. We study the equation for the magnetic helicity flux of a large-scale field and introduce a correction term related to the quadratic magnetic helicity invariant. [ABSTRACT FROM AUTHOR]

This study proposes a method to improve the permanent magnet synchronous motor (PMSM) dq0 model for torque using incremental inductance. The torque model is essentially a partial differential equation considering flux linkage and magnetic energy. In practice, non‐ideal factors, such as saturation non‐linearity, the cogging structure, and the distortion current, increase the difficulty of solving this equation. In this study, two parameters related to flux linkage and magnetic energy are derived using incremental inductance. In the differential range, they are independent of the currents. Therefore, the partial derivatives of flux linkage and magnetic energy can be expressed in the form of derivatives under the saturation non‐linearity conditions. Thereby a dq0 model that describes the torque ripple of a PMSM is established. This model can be used to calculate and analyse the transient characteristics of torque regardless of steady or unsteady current excitation. The main parameters of the model are obtained from finite‐element analysis (FEA). To reduce the dependency on FEA in the application, a derived version of this model is obtained by extending the range of the linearisation assumption. Finally, the rationality and effectiveness of the models are proven by comparison with the FEA and experiments, respectively. [ABSTRACT FROM AUTHOR]

The sources of energy of solar activity are analyzed. The primary source of solar energy is the core of the Sun, where as a result of the reactions of thermonuclear fusion, energy is released in the form of γ-quanta and neutrino particles that propagate outward. When approaching the surface due to the fall in temperature and the increase in the opacity of the substance, the fully ionized solar plasma, from certain depths, passes into the state of partial ionization. As a result, a Schwarzschild criterion of the emergence of a convective energy transfer due to hydrodynamic motions begins to run at a distance of 0.3 solar radius from the surface. Above this boundary lies a layer of convective turbulence, in which energy is transferred mainly by a moving substance, and not by radiation. It is called the convective zone. Ultimately, the part of the radiant energy transferred to the surface gives the opportunity to observe the Sun in different wavelength ranges. While the second part of the upward energy, which is due to convective motions, will manifest itself at the photospheric level in the form of granulation movements of various scales accessible for observation. However, part of the flow of energy coming from the interior of the Sun, accumulates and is carried upwards in the “magnetic form”. An important specific property of this highly effective mechanism of magnetic energy transfer is its significant variations in time, which are manifested in cyclic changes of the majority of phenomena generated by magnetic fields, called solar activity. The specificity of this energy transfer is manifested in the non-stationary flare conversion of magnetic energy into heat, as well as in the kinetic energy of accelerated particles and macroscopic (coronal) plasma emissions. The role of the landfill, where the main processes responsible for cyclic manifestations of solar activity originate, is played by the convective zone. In the depths of the convective zone, as a result of the dynamo mechanism, some of the kinetic energy of the hydrodynamic motions (differential rotation and gyrotropic turbulent convection) is converted into magnetic energy during the solar cycle, thereby strengthening the weak magnetic field of the Sun of relic origin. The global magnetic field generated in depths is transferred to the solar surface due to its magnetic buoyancy. Surface magnetic structures change the state of the Sun's atmosphere, cause an irregular part of the radiation and serve as a source of powerful non-stationary phenomena in the outer atmospheric layers (photosphere, chromosphere and corona). The modern concept of such phenomena as hot solar corona, solar wind and interplanetary magnetic field that form space weather in the interplanetary space is reviewed. The contribution of the “Kiev coronal school” of Vsekhsviatskij S.K. to the development of the concept of the dynamic corona of the Sun is noted.

Electric aircrafts capable of moving in three dimensions cause creation of new industries and applications in society. Also, electric aircrafts operate on minimal energy with low emissions. However, an electric aircraft must be ultra-lightweight. To produce an ultra-lightweight machine for electric aircrafts, the authors proposed a machine in which electrical energy is converted between the stator and rotor through magnetic resonance coupling (MRC). This action causes electromagnetic resonance between the multiphase windings of the stator and rotor. Electromagnetic resonance coupling technology allows electrical machines to convert energy without a magnetic core, thereby allowing the production of ultra-lightweight machines. In this study, authors describe a machine with three-phase windings based on MRC and discuss its operating principles and the basic characteristics induced by MRC. A model of this MRC machine was subjected to magnetic analyses to assess its rotational energy conversion in a rotating machine and to understand its basic characteristics. Authors’ results confirmed that MRC machines without a magnetic core could convert magnetic energy between the stator and rotor and produce sufficient starting torque and power at a power factor of 1.0. Furthermore, the machine was highly efficient, and its torque increased with resonant frequency.

An important challenge in the wireless power transfer is the sizing of the coils for transmission and energy reception. The output power in a wireless power transfer system can be determined by analytical formulation; however, the effects of using some geometry or material for the transmitter and receiver coil assembly are not easily quantifiable by the analytical method. This work quantifies by numerical simulation the impact on output power changing the separation between the transmitter coil and receiver, materials, geometries and number of turns. The quantities obtained allowed to determine a model for coupling coefficient to compute optimal frequency for the power transfer. The analysis and evaluation of these parameters were developed through an electromagnetic simulator with finite element; the work considers planar circular and square coils. Experimental results were obtained in order to validate the proposed model to compute the wireless power transferred. The document contributes to identify the important parameters to be controlled or modified in the coils with the purpose to optimize the power transmission for a wireless system. [ABSTRACT FROM AUTHOR]

Electric aircrafts capable of moving in three dimensions cause creation of new industries and applications in society. Also, electric aircrafts operate on minimal energy with low emissions. However, an electric aircraft must be ultra-lightweight. To produce an ultra-lightweight machine for electric aircrafts, the authors proposed a machine in which electrical energy is converted between the stator and rotor through magnetic resonance coupling (MRC). This action causes electromagnetic resonance between the multiphase windings of the stator and rotor. Electromagnetic resonance coupling technology allows electrical machines to convert energy without a magnetic core, thereby allowing the production of ultra-lightweight machines. In this study, authors describe a machine with three-phase windings based on MRC and discuss its operating principles and the basic characteristics induced by MRC. A model of this MRC machine was subjected to magnetic analyses to assess its rotational energy conversion in a rotating machine and to understand its basic characteristics. Authors' results confirmed that MRC machines without a magnetic core could convert magnetic energy between the stator and rotor and produce sufficient starting torque and power at a power factor of 1.0. Furthermore, the machine was highly efficient, and its torque increased with resonant frequency. [ABSTRACT FROM AUTHOR]

In this paper, a novel computational method that can accurately calculate the skewing leakage reactance of a doubly skewed rotor induction motor is proposed. It is based on the three-dimensional finite-element models to calculate the magnetic energy stored in every section of the machine and the rotor bar currents. In addition, the magnetic saturation and magnetic variation in the axial direction are taken into account in the models. Also, the proposed method is applied to calculate the stator leakage reactances and rotor leakage reactances. The comparisons between the testing results and the computational results show that the proposed method can obtain the more accurate results than the conventional computational algorithm. [ABSTRACT FROM AUTHOR]