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Several papers have appeared in recent years on the application of the amorphous soft magnetic materials in the stators of the electric motors. In our previous work, we demonstrated that the replacement of a slotless stator from the FeSi electrical steel with the stator from an amorphous alloy Metglas 2605 SA1 in a high-speed permanent magnet brushless direct current (PMBLDC) motor resulted in a substantial decrease of power losses in this stator, even by three times at the rotary frequency of 70 000 r/min. This paper was concentrated on the development of the cores for stators with half-open slots, which are technologically more difficult to produce than the slotless cores. The cores were made by cutting out suitable amount of $25~\mu \text{m}$ -thick rings from the FeSiB amorphous ribbon by a laser technique, followed by stacking up the rings and their consolidation, and suitable heat treatment of the compressed stacks. Next, the measurements of the magnetic properties of the sample cores with half-open slots were made using the Remacomp C-1200 hysteresisgraph and the Lakeshore 450 Gaussmeter. Based on the results of measurements, the sample cores of different heights (17.5 and 10 mm) were selected for application in a stator of the prototype high-speed PMBLDC motor, 800 W in rated power and with a maximum rotary speed of 60 000 r/min. The preliminary performance tests with this prototype motor showed that after 1 h of uninterrupted operation, the temperature of a motor housing did not exceed 60 °C. It was also found that the operating efficiency of the PMBLDC motor incorporating a stator with half-open slots, made from an amorphous material, was almost 90% over a wide range of torques (from 40 to 140 mN $\cdot \text{m}$ ).

This paper describes the magnetic cooling device model designed and built at the Institute of Non-Ferrous Metals in Gliwice, which utilizes reciprocating motion of a magnetic field source and a cyclic flow of a coolant through regenerator. The regenerator made from gadolinum made it possible to obtain an adiabatic temperature change of 2.5 K at the magnetic field of 0.8 T. The magnetic field source was built using neodymium magnets according to our own technology. For the heat transfer, a liquid having the specific heat of about 4000 J/(kg K) has been applied. We have also developed and applied a special driving system enabling reciprocating motion of the magnetic field source and of the pistons in the hot and cold heat exchangers. The tests were made with this cooling model showing that it was possible to obtain, at the frequency of 0.5 Hz, the liquid temperature gradient of 4 K. The potential energy savings resulting from application of this device have been evaluated and compared with the literature data presenting a pre-industrial prototype of the magnetic refrigerator utilizing similar solutions to those applied in our cooling model.

The rapidly quenched soft magnetic materials have found many practical applications in power electronics, electric engineering, telecommunications, and other industrial sectors. The aim of this paper was to present the results of a research on fabrication technology of the amorphous and nanocrystalline cores intended for: 1) soft magnetic cores for the stators of the high-speed permanent magnet brushless direct current (PMBLDC) motors; 2) nanocrystalline soft magnetic cores for application in high-frequency power conversion; and 3) three-limb amorphous cores for the three-phase distribution transformers. The cores intended for the stator of the high-speed PMBLDC motor were made from the Metglas 2605 SA1 ribbon and then subjected to the performance tests in a model of an electric motor. The research on soft magnetic materials for high-frequency high-power conversion was concentrated on the Finemet rectangular cores with a gap and the composite ones with distributed gap, and the comodified Finemet cores with the induced transverse magnetic anisotropy. The three-limb cores for 400 kVA three-phase distribution transformer were made from the Metglas 2605 SA1 ribbon and subjected to the performance tests in electricity distribution network. It was found that all the amorphous and nanocrystalline cores fabricated under this paper enable considerable reduction in power losses.

An effect of interlaminar insulation on the dynamic magnetic properties of the tape-wound FeNiCuNbSiB-type nanocrystalline cores was investigated. This insulation was prepared by three methods. After thermomagnetic treatment of toroidal cores selected types of suitably chosen varnishes were applied onto the core edges so as to enable their in-depth penetration thus forming the desired insulation. In the final stage of thermomagnetic treatment, conducted initially under protective atmosphere of argon, oxygen was introduced to the process to enable formation of interlaminar oxide layer. Finally, the ribbon was coated with SiO layer prior to its winding into the core. Then, dynamic magnetic properties of the cores were measured within a frequency range from 50 Hz to 100 kHz. It was found that the use of a modified acrylic-type resin resulted in the decrease of the Fe73.8Ni5Cu0.6Nb2.6Si9B9 core losses at higher frequencies. In the cores with an oxide insulation, reduction of power losses was observed at lower frequencies. The use of interlaminar SiO insulation resulted in considerable reduction of core losses above the frequency of 5 kHz. The results of this paper can be practically applied in the production of nanocrystalline cores for power electronic equipment.

This paper presents results of a research work related to the development of the production technology of the amorphous cores designed for application in permanent magnet brushless direct current (PMBLDC) motors. The cores were made from the Metglas 2605 SA1 amorphous ribbon, from which rings of the specific external and internal diameters were cut using a laser technique. Next, the rings were stacked up so as to form a core of a required height, subjected later to the consolidation by pressing, followed by an appropriate heat treatment. Finally, the cores were coated with an epoxy resin to protect them against delamination and used as stators in a prototype high-speed electric motor, 1 kW in rated power and 70 000 rpm in a rotary speed. The motor incorporating these amorphous cores was subjected to the performance tests, which confirmed their proper operation and satisfactory mechanical characteristics and efficiency. It was found that power losses in the stators from the amorphous material were considerably smaller than those in the conventional stators from the silicon steel, and they did not exceed 7 W. Therefore, an application of the amorphous soft magnetic materials in the high-speed PMBLDC motors may contribute to eliminating the need of using additional cooling systems in these motors.

Transverse magnetic anisotropy has been induced in the Fe 14.7 Co 58.8 Cu 1 Nb 3 Si 13.5 B 9 and Fe 13.8 Co 65 Cu 0.6 Nb 2.6 Si 9 B 9 amorphous ribbons by annealing under an external magnetic field. This anisotropy plays a predominant role, compared to magneto-crystalline and magneto-elastic anisotropies, in forming the magnetic properties and shaping the hysteresis loop. The effect of temperature and time of annealing on the induced magnetic anisotropy and magnetic properties (magnetic permeability, coercivity and power losses) in both alloys was investigated. Under this work, measurements of frequency dependence of the real and imaginary parts of magnetic permeability were made within a frequency range up to 110 MHz. It was found that as a result of magnetic field annealing the Snoek limit increases in both alloys compared to the Co-free Finemet.

This work was aimed at investigating the FeNbCuSiB and FeNiMoB type alloys exhibiting relatively high saturation magnetostriction after suitable heat treatment, which makes them suitable for application in force sensors. Samples of both alloys were prepared in a form of toroidal cores wound from amorphous ribbons obtained by melt-spinning, and then the cores were annealed under longitudinal and transverse magnetic field. An effect of the induced magnetic anisotropy and of the applied compressive stresses on the dynamic magnetic properties of both alloys within a frequency range from 50 Hz to 50 kHz was studied.

The influence of partial substitution of Fe by Co in Fe 7 8 . 8 - x Co x Cu 0 . 6 Nb 2 . 6 Si 9 B 9 alloy (x = 0, 20, 40, 60) on soft magnetic properties has been investigated for application at high frequency range. The affect of the value of transverse magnetic field and duration of the annealing on the induced magnetic anisotropy were examined. The magnetic properties of FeCoCuNbSiB nanocrystalline alloys were measured in dependence on magnetizing field frequency (10 Hz - 300 kHz). The transverse magnetic anisotropy induced in the Fe 7 8 . 8 - x Co x Cu 0 . 6 Nb 2 . 6 Si 9 B 9 alloys improves significantly their performance during operation at high-frequency fields and makes them very attractive material suitable for application in power electronic devices.

Magnetic properties of the cores made from the (Fe1−xCox)73.5Cu1Nb3Si13.5B9 alloy (x=0.136, 0.272, 0.408, 0.544, and 0.680) were investigated within frequency range of 0.05–50 kHz and at the environment temperatures ranging from 298 to 643 K. It was found that the alloy with Co content corresponding to x=0.136 has the best high-temperature and high-frequency magnetic properties in comparison with the other alloys investigated in this work.

Dynamic magnetic properties of a new FeCoNbBP alloy were measured under four types of voltage excitation: sinusoidal, triangular, square and ramp. Samples were prepared in a form of toroidal cores wound from melt-spun amorphous ribbons and subjected to suitable thermo-magnetic treatment in a transverse magnetic field. The measurements were carried out within a frequency range from 1 to 50 kHz using a computerized hysteresis loop tracer fitted with the function generator enabling non-sinusoidal voltage excitation. It was found that the core losses for this material clearly depend on excitation conditions and over the frequency range studied they were generally higher at triangular waveform and lower at square waveform compared to sinusoidal excitation. At the square wave voltage excitation, the differences were reaching 19%.

The research results for different stages of production of a three-phase 250 kVA distribution transformer using three-limb amorphous magnetic core have been presented. The core is made from six frames wound from 23 μm thick Metglas 2605 TCA ribbon. Magnetic characteristics for the frames and three-limb core were measured. The 250 kVA distribution transformer was manufactured.

The magnetic domain structure is a specific property of ferromagnetic materials influencing their main magnetic properties. The aim of this work was to determine a relationship between nanocrystalline and the domain structure observed by means of magneto-optic Kerr effect on the surface of the Fe14.7Co58.8Cu1Nb3Si13.5B9 and Fe13.8Co65Cu0.6Nb2.6Si9B9 toroidal cores, and the induced transverse magnetic anisotropy Ku. The transverse magnetic anisotropy was induced in the Fe14.7Co58.8Cu1Nb3Si13.5B9 and Fe13.8Co65Cu0.6Nb2.6Si9B9 amorphous cores by annealing them at the temperature of 460 °C, under an external magnetic field of 500 kA/m. It was found that the appearance of nanocrystalline phase in the Fe13.8Co65Cu0.6Nb2.6Si9B9 alloy resulted in considerable increase of the magnetic anisotropy constant to 900 J/m3 already after 40 minutes of heating, whereas the nanocrystallization process in the Fe14.7Co58.8Cu1Nb3Si13.5B9 alloy proceeded much slower (after 240 minutes of heating the content of nanocrystalline p...

This work was aimed at investigating the FeNiMoB type alloys exhibiting relatively high saturation magnetostriction after suitable heat treatment, which makes them suitable for application in force sensors. Crystallization process of amorphous alloy was examined by DSC. Temperatures and enthalpies of both stages of crystallization were determined from DSC upon continuous heating from a room temperature to 993 K with constant heating rate of 20 K/min. Next, samples were isothermally annealed under longitudinal and transverse magnetic fields within the temperature range of 623–833 K for 1 h under Ar protective atmosphere. Structure of the alloys was checked by means of XRD and TEM. After annealing, the AC (50 Hz) magnetic properties (coercivity, magnetic induction) were determined using a computerized hysteresis loop tracer. An effect of the annealing temperature, induced magnetic anisotropy and of the applied compressive stresses on the dynamic magnetic properties of the alloys was studied within a frequency range from 50 Hz to 50 kHz. Our studies confirmed that the Fe-Ni-Mo-B alloy annealed at 653 K is the most suitable for application in force sensors. Moreover, the results obtained indicate that for the measurements of compressive stresses below 0.3 MPa it is more advantageous to use the cores with longitudinal anisotropy, whereas the cores with a transverse magnetic anisotropy are more suitable for application at the compressive stresses over 0.3 MPa.

The nanocrystalline cores made from rapidly-quenched amorphous ribbons are increasingly used in power electronics, particularly in high-frequency and high-temperature applications. Under this work, the influence of ribbon thickness and of an emulsion coating applied between ribbon coils on soft magnetic properties of nanocrystalline toroidal cores made from this ribbon was investigated. The amorphous ribbons of different thickness were cast by rapid-quenching from the FeCuNbSiB and FeCoNbBP alloys and next toroidal cores were wound from them. The cores were prepared with and without the use of an emulsion insulation and subjected to thermo-magnetic treatment conducted under protective atmosphere of argon. Next, soft magnetic properties of the cores were measured within a frequency range from 50 Hz to 300 kHz. It was found that the ribbon thickness and the use of ribbon coating influence soft magnetic properties of both studied alloys.

Fabrication conditions of the Pd47Ni47Si6 amorphous ribbons designed for functional application as a filler metal in joining metallic elements have been developed. Particular attention in developing fabrication technology was drawn to the question of elimination of ribbon contamination with carbon, the presence of which has disadvantageous effect on the quality of the amorphous PdNiSi brazes. Thermodynamic properties of the PdNiSi braze were examined and its characteristic temperatures TS and TL have been determined. Density and resistivity of the ribbons have been measured. Moreover, brazing tests were conducted using the brazing alloys fabricated under this work, designed for joining such metals as ST3S constructional steel, tungsten, molybdenum and tantalum. The strength tests were also carried out confirming very good functional properties of the developed brazing alloy.

A set of the simple and practical expressions for the CMRR of instrumentation amplifiers (IAs) based on 2, 3 and 4 opamps is given. These equations take into account not only mismatch of determined resistors but also the limited value of the CMRR of op-amps used. The derived equations are very useful for tolerance analysis which is shown on the example of the 3-op-amp IA