Ferromagnetic core with high permeability composed with strength winding in short circuit current

The motor of traditional silicon material possesses the disadvantages of high iron loss, power consumption and a low efficiency. A new type of motor iron core made of amorphous alloy material is put forward in this paper. First, in order to research the stator characteristics of amorphous iron core and silicon steel core, the stator core of three-phase asynchronous motor is fabricated with silicon and amorphous materials. The magnetic performances and alternating loss of the iron cores made by two kinds of materials are tested with in the TD8120 test system. Then, the finite element analysis model of three-phase asynchronous motor is established. The motor of amorphous iron core and silicon steel core are simulated by finite element method. It is showed that the simulation and test results are in good condition within error range. It can be known that the performance and efficiency of motor made by amorphous alloy core are better than the performance and efficiency of motor made by silicon steel core. Results presented in this paper have important significance to carry out the study of amorphous motor.

The article discusses the advantages of using magnetic cores of distribution transformers made of amorphous steel in comparison with traditional electrical steel. This is due to the unique properties of amorphous steel, facilitating the process of magnetization and demagnetization, which can significantly reduce eddy current losses and hysteresis losses. The magnitude of iron losses in the power transformer is determined by the configuration and materials of its magnetic core. In connection with the rise in price of electric energy, the task of reducing idling losses, increasing efficiency, reducing costs and increasing the reliability of the operation of the transformer is an urgent task. Design features of the amorphous steel magnetic core in distribution transformers made it possible to obtain the best characteristics in the short circuit mode due to the reliable construction of the winding block and the unique properties of the main and insulating materials. An important improvement in the field of design was the use of aluminum tape for the production of windings of such a transformer, which made it possible to use rectangular windings and increase their electric strength. Reinforced insulation with a baked epoxy layer after heat treatment is used as the material of the interlayer insulation. The article also discusses the technology of manufacturing a magnetic core from amorphous steel with assembly steps, and also describes the design and assembly features of a distribution transformer with an amorphous steel core. The use of materials with improved characteristics, materials based on amorphous alloys and the use of modern technologies for the manufacture of the magnetic core can have a big impact on the idling losses and no-load current of the transformer.

Fe-based amorphous powder cores of Fe–Si–B–Cr–C magnetic powder and phenolic binder were fabricated, and the effects of annealing and compaction pressure on the soft magnetic properties and core loss were investigated. The formation of Fe–B and α-Fe (Si) phases was confirmed at the annealing temperature above 773 K. The density gradually increased from 5.3 to 5.5 g/cm3 as annealing temperature increased, resulting in the saturation magnetization 4πMs increased to 1.0 T at 773 K. The effect of compaction pressure was studied by using samples annealed at 723 K. Both the density and 4πMs enhanced with compaction pressure from 980 to 1960 MPa. The real part of permeability µ’ remained constant for the frequency up to 2 MHz. The initial value of µ’ increased from 25 to 38 with compaction pressure. Consequently, at Bm of 50 mT and frequency of 100 kHz, the considerably low core loss of 67 kW/m3 was obtained. The low core loss and moderately high permeability of Fe–Si–B–Cr–C amorphous powder core across a wide frequency range indicate its potential for application in high frequency electronic components.

Transcranial magnetic stimulation (TMS) is a safe, effective and non-invasive treatment for several psychiatric and neurological disorders. Lately, there has been a surge in research utilizing this novel technology in treating other neurological and psychiatric ailments. The application of TMS on several neurological disorders requires the induced electric and magnetic fields to be focused and targeted to a small region in the brain. TMS of a focal cortical territory will ensure modulation of specific brain circuitry without affecting unwanted surrounding regions. This can be achieved by altering the properties of the magnetic core material used for the TMS system. In this study, soft ferromagnetic materials having high permeability, high saturation magnetization and low coercivity have been investigated as TMS coil cores in finite element simulations. Also, magnetic field measurements have been carried out using different cores in the TMS coil. Finite element analysis of the rat head model is carried out using Sim4life software while investigating variations associated with changing the ferromagnetic core material and shape in the coil. Materials proposed for the analysis in this study include Iron Cobalt Vanadium alloy (Fe-Co-V) also known as Permendur, Carbon Steel (AISI 1010) and Manganese Zinc ferrites (MnZn ferrites). Simulation results indicated significant magnetic field distribution variation when introducing a ferromagnetic core in TMS coil, concentrating the magnetic field to the targeted region in the rat head model without stimulating adjacent regions. It was observed that the v-tip sharpened core attained the highest magnetic field and best focality among other cores in simulations and experimentally.

Fe-based amorphous powder cores with low core loss and high permeability fabricated using the core-shell structured magnetic flaky powders

Dynamic characteristics of Co-rich amorphous magnetic cores have been examined based on the Control Magnetization Curve (CMC). Frequency dependence of CMC for amorphous and other soft magnetic cores has also been examined up to f=20kHz. It is found that amorphous cores have many advantages as magnetic materials used for instrumentation and control devices which operate in a high frequency region.

<p indent="0mm">The third-generation semiconductor (also known as the “wide energy gap semiconductor”, WBG) has been widely adopted and applied in strategic emerging industries. As the digital age unfolds, computing ability has become an important indicator of a country’s comprehensive national strength. The physical foundation for high computing power requires AI hardware to enable high energy density, high integration, and miniaturization. Given its key role in circuit energy conversion, the inductor must not only exhibit high energy density but also maintain excellent electrical and magnetic properties, posing significant challenges in minimizing losses during high-frequency operation. Therefore, it is imperative to develop new inductors and soft magnetic materials for high-power density and high-frequency applications. Recently, Fe-based amorphous and nano-crystalline alloys have attracted great attention in scientific research and industry because of their high saturated magnetic flux density and low core loss. Under high-frequency operating conditions, they are expected to bridge the performance gap between traditional silicon steel and soft magnetic ferrite materials in terms of high-power density and low core loss. Given their unique preparation methods, atomic structures, high strength, and hardness, it is necessary to develop specific processing and heat treatment methods tailored to amorphous and nano-crystalline alloys for industrial applications. This paper reviews the progress of Fe-based amorphous/nano-crystalline soft magnetic materials, including their development, preparation, processing, and industrial applications. The challenges and future development trends of amorphous/nano-crystalline soft magnetic powders and powder cores in potential industrial applications are discussed.

The characteristics of magnetomodulation sensors of magnetic flux density with autoparametric amplification of the signal in amorphous ferromagnetic cores are considered. It is shown that, by comparison with ferromagnetic probes (fluxgate devices), such sensors possess a lower level of magnetic noise at low frequencies, though greater zero instability in the measurement of a static magnetic field. Ways of improving the metrological characteristics of the sensors are proposed.

We report microfabricated toroidal inductors with nanolaminated ferromagnetic metallic cores for chip-scale, high-power switching converters. The fabrication process of the toroidal inductor is based on individual manufacturing of partial windings (i.e. bottom and vertical conductors) and nanolaminated magnetic core, and integrating them by means of a drop-in approach. The nanolaminated ferromagnetic metallic cores presented in this paper consist of many multilayers of electrodeposited CoNiFe films, each layer with sub-micron thickness, with a total core thickness exceeding tens of microns. The beneficial magnetic properties (i.e. high saturation flux density and low coercivity) of CoNiFe alloys are well suited for chip-scale inductors as they achieve both large energy storage capacity as well as minimized volumetric core losses at high operating frequencies due to their nanolaminated structure. A drop-in integration approach, introduced to combine the microfabricated toroidal inductor windings with the magnetic cores, allows ease of integration. An advantage of this hybrid approach over monolithic fabrication in this application is the potential use of a wide variety of core materials, both microfabricated and bulk-fabricated, and which may or may not ultimately be CMOS-compatible. Exploiting this drop-in approach, 30-turn- and 50-turn-toroidal inductors integrated with nanolaminated CoNiFe cores, having 10 mm outer diameter and 1 mm thickness, have been successfully developed. Both types of inductors exhibit inductances higher than 1 µH at frequencies up to tens of MHz, showing ten times the inductance of an air core device with the same nominal geometry. The peak quality factor of the 30-turn-toroidal inductor reaches 18 at 1 MHz.

A new method of obtaining physical information about a system of fine ferrite powder, from the hysteresis experienced by a ferromagnetic core as it dissipates energy in an RLC circuit is presented. The models of the magnetization processes are classified in three categories: physical, phenomenological and mixed. Hodgdon developed a purely mathematical model that was tested on magnetization processes in magnetic cores. The values of the model's parameters are calculated from experimental data obtained in a series RLC circuit. The capacitor discharges through the circuit and the core performs a complex magnetization process. The voltage across the capacitor and the current intensity are measured. These magnetization processes could be also simulated with a mixed-type model. The identification methodology of the mixed model requires the measurement of some magnetization curves: the first magnetization curve, the major hysteresis loop, the isothermal remanent magnetization process and the d.c. demagnetization process. In order to preserve the simplicity of the experimental data measurement and to perform the identification of the mixed model, some of the experimental curves required by the identification methodology were simulated with the Hodgdon model. Experiments were performed on soft MnZn ferrite core. The results of the identification are discussed.

Reducing the core loss of amorphous cores for distribution transformers

We have developed a micro fluxgate magnetic sensor using new printed circuit board (PCB) technology. The fluxgate sensor consisted of five PCB stack layers including one layer of magnetic core and four layers of excitation and pick-up coils. The center layer as a magnetic core was made of micro patterned amorphous magnetic ribbon with an extremely high DC permeability of ~100,000, and the core had a rectangular ring shape. Four outer layers as an excitation and pickup coils had a planar solenoid structure. The amorphous magnetic core was easily saturated due to the high permeability, low coercive field, and closed magnetic path for the excitation field. The chip size of the fabricated sensing element was 7.3 × 5.7 mm2. Excellent linear response over the range of –100 μT to +100 μT was obtained with sensitivity of 780 V/T at excitation sine wave of 3 Vp-p and 360 kHz. A very low power consumption of ~8 mW was measured. This low power, small size, and high sensitive fluxgate sensor to measure a low magnetic field is very useful for various applications.

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BackgroundInformation transmission and processing in the nervous system has stochastic nature. Multiple factors contribute to neuronal trial-to-trial variability. Noise and variations are introduced by the processes at the molecular and cellular level (thermal noise, channel current noise, membrane potential variations, biochemical and diffusion noise at synapses etc). The stochastic processes are affected by different physical (temperature, electromagnetic field) and chemical (drugs) factors. The aim of this study was experimental investigation of hypotheses that increase in the noise level in the brain affects processing of visual information. Change in the noise level was introduced by an external factor producing excess noise in the brain.MethodsAn exposure to 450 MHz low-frequency modulated microwave radiation was applied to generate excess noise. Such exposure has been shown to increase diffusion, alter membrane resting potential, gating variables and intracellular Calcium efflux. Nine healthy volunteers passed the experimental protocol at the lower (without microwave) and the higher (with microwave) noise level. Two photos (visual stimuli) of unfamiliar, young male faces were presented to the subjects, one picture after another. The task was to identify later the photos from a group of six photos and to decide in which order they were presented. Each subject had a total of eight sessions at the lower and eight at the higher noise level. Each session consisted of 50 trials; altogether a subject made 800 trials, 400 at the lower and 400 at the higher noise level. Student t-test was applied for statistical evaluation of the results.ResultsCorrect recognition of both stimuli in the right order was better at the lower noise level. All the subjects under investigation showed higher numbers of right answers in trials at the lower noise level. Average number of correct answers from n=400 trials with microwave exposure was 50.3, without exposure 54.4, difference 7.5%, p<0.002. No difference between results at the lower and the higher noise level was revealed in the case of only partly correct or incorrect answers.ConclusionsOur experimental results showed that introduced excess noise reduced significantly ability of the nervous system in correct processing of visual information.

Generally, as operating frequency becomes higher, magnetic components get smaller and lighter. However, higher frequency leads to larger core loss and copper loss. Therefore, the appropriate material of the core and operating frequency needs to be determined to realize well-designed magnetic components. So far, a silicon steel sheet has been used in the low frequency range for large-capacity conversion systems, and ferrite has been used in the high frequency range for small-capacity conversion systems. Recently, new magnetic cores with, for example, amorphous and nanocrystalline materials have been developed that have high saturation magnetic flux density and low core loss. However, the appropriate operating frequency for each magnetic core has not been determined quantitatively. In this study, a novel evaluation method for the volume of transformers using various magnetic cores is proposed. As a result, the volume indicator of the nanocrystalline material has the lowest volume in the range of 1.5 – 40 kHz, and it is the best to operate the nanocrystalline material at 5 kHz for both high efficiency and small size when the saturated temperature rise is 40 K.