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In this paper, in order to make a clear principal cause in increasing iron loss of amorphous wound cores in processing, effects of bending stress on magnetic characteristics of a Fe-based amorphous wound core are clarified. The amorphous magnetic materials have been widely used as a core material of power transformers to reduce iron loss due to their excellent soft magnetic characteristics. However, the amorphous magnetic material has an issue that the building factor (B.F.) is very large in comparison with that of grain-oriented electrical steel sheets. The amorphous transformers usually use a wound core formed by stacking plural amorphous sheets in different lengths. Bending stress is, therefore, generated at each corner of the wound core in processing. Due to this bending stress, the magnetic characteristics of the wound core deteriorate. The deterioration of magnetic characteristics of the wound amorphous core is so large because of the large magnetostriction constant. As a result, the B.F. of this material becomes larger. In order to remove the residual stress, which is generated in the wound core including the bending stress, the amorphous wound core is usually annealed in a magnetic field, which is called “a magnetic annealing.” In this paper, the effect of the magnetic annealing on the magnetic properties is studied experimentally by evaluating some wound amorphous model cores. As a result, a suitable magnetic annealing condition is clarified and the iron loss of the wound amorphous model core is reduced by 65.7%. [ABSTRACT FROM AUTHOR]

We report theoretically and experimentally a passive bidirectional current–voltage ( $I$ – $V$ ) converter, capable of converting input currents into output voltages, and conversely, input voltages into output currents, based on a multiphase heterostructured magnetoelectric (ME) ring. The ME ring has a coil-wound, intermagnetically biased magnetostrictive–piezoelectric (MS–PE) heterostructure, in which an axially polarized PZT PE ceramic ring is bonded between two circumferentially magnetized, intermagnetically biased Terfenol-D short-fiber/NdFeB magnet/epoxy three-phase MS composite rings. In $I$ – $V$ conversion, a current applied to the coil induces a vortex magnetic field to the ME ring, resulting in an open-circuit voltage from the ME ring because of the direct ME effect. In voltage–current ( $V$ – $I$ ) conversion, a voltage applied to the ME ring produces a circumferential magnetic induction due to the converse ME effect, leading to a short-circuit current from the coil. The converter exhibits simultaneously large $I$ – $V$ and $V$ – $I$ conversion factors of $\sim 0.3$ V/A and $\sim 0.2$ mA/V in a broad non-resonance frequency range up to 80 kHz as well as enhanced conversion factors of $\sim 7$ and $\sim 25$ times at the resonance frequency of 122 kHz, respectively. [ABSTRACT FROM PUBLISHER]

The paper presents a practical view on industrially used magnetic cores wound from Ni-Fe tape. The discrepancies between various international suppliers are quite wide, which can have a significant impact on production and in effect on magnetic performance of the final devices. [ABSTRACT FROM PUBLISHER]

This paper proposes a three-phase five legged wound transformer core constructed of two high permeability Si-Fe wound cores and two conventional Si-Fe wound cores. The two large internal wound cores are manufactured of high permeability, grain-oriented electrical steel. The two small outer wound cores are manufactured of conventional, grain-oriented electrical steel. The specific arrangement is based on experimental evidence concerning the peak flux density non-uniformity of the typical three-phase five legged wound transformer core, constructed of the high magnetization grain-oriented steel. Since the peak flux density of the two outer cores is lower than the two internal cores, low cost, low permeability, conventional grain-oriented electrical steel can be used for the outer cores. Losses, excitation currents, flux waveforms, and their harmonics contents are presented in this paper. A comparison of the mixed three-phase transformer core and the typical one is also carried out. [ABSTRACT FROM PUBLISHER]

A floating magnetic rotor is synchronized to a rotating magnetic field in the developed pump. We cannot measure or calculate the magnetic torque using a general measurement method because the angle theta (\theta) represents the unknown factor between the magnetic field and the magnetic moment on the magnetic rotor. We have converted the relationship between the rotating magnetic field and the rotation of the magnetic rotor to an electrical signal using Faraday's law. Converted signals have a phase difference that is converted to the angle theta (\theta) in the magnetic torque. This has allowed us to calculate the magnetic torque. [ABSTRACT FROM AUTHOR]

This paper propounds a practice of using cut cores with a distributed air gap in the production of magnetic circuits for high quality medium voltage instrument transformers. It discusses utilization, for this purpose, of both grain-oriented and non-oriented electrical steel sheets of different grades, hence of considerably different characteristics and cost. The magnetic properties of the transformers were enhanced, and substantial technical and economical benefits in the manufacture of the end product were realized. [ABSTRACT FROM PUBLISHER]

We describe the construction of a thermomagnetic analyser that uses a microfurnace. The equipment can work in the temperature range of -30/spl deg/C up to 1000/spl deg/C, with heating/cooling rates as high as 50/spl deg/C/min. without temperature hysteresis. The design allows the use of excitation and pick-up coils with thousands of turns, working at room temperature. This gives a high sensitivity to the equipment as revealed by the measurement of magnetic transitions in thin films with masses in the order of 500 /spl mu/g. The reproducibility of the measurements is very good, and there is only noticeable drift in the most sensitive range. [ABSTRACT FROM PUBLISHER]

A human-size magnetic shield of cylindrical structure (inner diameter: 92 cm, length: 220 cm) has been constructed with magnetic shaking enhancement. The weights of the magnetic materials used are 69 kg for Metglas 2705M amorphous tapes and 40 kg for Permalloy tapes and the total weight was about 250 kg. The shielding factor at the center was 4000 for a transverse magnetic field of 10 /spl mu/T, 1 Hz and residual dc magnetic field was as small as 1-2 nT when compensation for open ends was applied. The noise level of the shield measured, when open end compensation was off, by a SQUID magnetometer at the center of the shield was 54 fT//spl radic/Hz at 1 Hz and 23 fT//spl radic/Hz at 10 Hz. [ABSTRACT FROM PUBLISHER]