1,721,005 research outputs found
Novel method for evaluating the iron losses in SMC materials
No full textIndustrial systems comprehending reduced losses components are always more and more requested: the Standards push towards the improvement of the efficiency, and this forces to find new solutions to fulfill the constraints. For laminated steels appropriate methods to measure or estimate the iron losses are applied: Epstein frame or Single Sheet Tester (SST) for measurements, FEM simulation and analytical approach to estimate the penetration of the losses due to mechanical processing. In the case of the Soft Magnetic Composites (SMC) the test method normally adopted is the one with toroidal samples, which cannot give information about the losses distribution and the contribution due to processing. For this reason a new method based on a thermographic analysis is proposed: a contactless and non-destructive technique to evaluate the core losses and their distribution has been developed. The principle is based on the observation of the temperature changes distribution on the device surface; a deep elaboration of the temperature information allows to deduce the specific iron losses distribution. In this way it is possible to analyze in details the energetic behavior of the SMC and also to evaluate the impact of some process parameters (molding pressure, orientation etc.) on the losses; moreover the method could be applied to devices of every shape and dimension and adopted also outside the laboratories facilities
Novel method for evaluating the iron losses in SMC materials
No full textIndustrial systems comprehending reduced losses components are always more and more requested: the Standards push towards the improvement of the efficiency, and this forces to find new solutions to fulfill the constraints. For laminated steels appropriate methods to measure or estimate the iron losses are applied: Epstein frame or Single Sheet Tester (SST) for measurements, FEM simulation and analytical approach to estimate the penetration of the losses due to mechanical processing. In the case of the Soft Magnetic Composites (SMC) the test method normally adopted is the one with toroidal samples, which cannot give information about the losses distribution and the contribution due to processing. For this reason a new method based on a thermographic analysis is proposed: a contactless and non-destructive technique to evaluate the core losses and their distribution has been developed. The principle is based on the observation of the temperature changes distribution on the device surface; a deep elaboration of the temperature information allows to deduce the specific iron losses distribution. In this way it is possible to analyze in details the energetic behavior of the SMC and also to evaluate the impact of some process parameters (molding pressure, orientation etc.) on the losses; moreover the method could be applied to devices of every shape and dimension and adopted also outside the laboratories facilities
A Novel Thermographic Method and Its Improvement to Evaluate Defects in Laminated and Soft Magnetic Composites Devices
No full textElectromagnetic devices may be affected by the presence of local losses due to material defects or magnetic anomalies caused by mechanical processing. The localization of such defects is the main goal of this article; a noninvasive method has been pursued to perform the inspection and detection of imperfections or defects. The adopted approach is based on the observation of the device under test with a high-speed IR camera; no limitations in size and shapes devices are considered and the method can be widely adopted. Examples of defects detection in the magnetic circuit realization are proposed, both for traditional ferromagnetic laminated sheets and for soft magnetic composites
The Magnetization Effect on Soft Magnetic Composite Prepared Stators of Axial Flux Motors
No full textThe axial flux motors should represent a good and reliable solution for a large variety of applications. The use of soft magnetic composite materials allows to resolve some drawbacks of the aforementioned motors. Two axial flux motors have been prepared with the same design. The unique difference consists of soft magnetic composite stator preparation. The magnetization effect during the stators production process has been evaluated. Different tests have been performed in order to compare a magnetized and a not magnetized stator. Distinct differences have been noted, showing some advantages for the prototype with aligned SM C material
Two-Winding Procedure for the Measurement of the Anhysteretic Curve Points and Small-Signal Magnetic Permeability of Ferromagnetic Materials
No full textAt a first approximation and sufficiently low frequencies, two macroscopic phenomena influence the hysteresis cycle shape in ferromagnetic materials: magnetic hysteresis and magnetic saturation. Different magnetic models use the anhysteretic curve as a fundamental locus in the magnetic material representation. In the literature, many authors proposed easier measurement methods to obtain the anhysteretic curve, or methods, which envisage the use of standard equipment already available on the market. In the present work, a measurement procedure is outlined, involving only two windings, being partly or fully compliant with the sample preparation described in the 60404 standards. Additionally, the proposed method is suitable to measure the small-signal permeability in each point of the anhysteretic curve right after the determination of the point itself. Also, the local magnetic permeability is obtained directly from the measurement. The method is executed on three toroidal samples made of different materials: a laminated sheet, a Soft Magnetic Composite and an amorphous ferrite core. The results are then compared with those of a very low frequency, large cycle conventional measurement, showing a good matching with the expected anhysteretic behavior of the three materials
Two-winding procedure for the measurement of the anhysteretic curve points of ferromagnetic materials
No full textAt a first approximation and sufficiently low frequencies, two macroscopic phenomena influence the hysteresis cycle shape in ferromagnetic materials: magnetic hysteresis and magnetic saturation. Different magnetic models use the anhysteretic curve as a fundamental locus in the magnetic material representation. In the literature, many authors proposed easier measurement methods to obtain the anhysteretic curve, or methods, which envisage the use of standard equipment already available on the market. In the present work, a measurement procedure is outlined, involving only two windings, being partly or fully compliant with the sample preparation described in the 60404 standards. Additionally, the proposed method is suitable to measure the small-signal permeability in each point of the anhysteretic curve right after the determination of the point itself. The method is executed on three toroidal samples made of different materials: a laminated sheet, a Soft Magnetic Composite and an amorphous ferrite core. The results are then compared with those of a very low frequency, large cycle conventional measurement, showing a good matching with the expected anhysteretic behaviour of the three materials
Uncovering turbulence of dust particles in the Hartmann tube through the Image-Subtraction Method
Full text linkThe present work investigates the dynamics of dust clouds in space and time when dispersed inside the modified Hartmann tube commonly used for explosibility screening and Minimum Ignition Energy (MIE) measurement. This study focuses on the fluid dynamics of the dust cloud in the space between the electrodes where the ignition occurs since fundamental properties of the dust motion, such as the cloud turbulence (intensity and variation), are known to affect both the ignition sensitivity and explosion severity significantly. An imaging re-elaboration method based on an algorithm (Image-Subtraction Method, ISM) is presented and adopted in the basics of the present research. To clarify the cloud dynamics, a novel approach is proposed here, using LabVIEW specific algorithms, namely Particle Analysis and optical flow detection methods, which allow the tracking of the motion and the velocity vectors of dust clusters identified in the cloud flow. Concurrently, measuring the intensity of concentration changes between the electrodes (luminance change of the video frames in time and space) and cloud velocity, which likely represents the turbulence, is possible. Different types of dust (iron, starch, silica) were used at different dispersion conditions (dispersion pressure and dust amount). The cloud motion was recorded, and videos were analyzed through LabVIEW to explore the parameters affecting dust turbulence (powder-specific gravity, particle size distribution, and air blast intensity). The outcomes of this work will help characterize the flow of a dust cloud inside a tube before its ignition and better define the optimal testing conditions for MIE determination
Rare Earth Magnets Recycling: Study of a Safer and Cost-Effective Technique
No full textRare Earth magnets are currently adopted in different industrial sectors, from household utilities to automotive applications, informatics to sensors, etc. Rare Earth magnets show the best magnetic performance, predominantly in the case of Neodymium magnets, and help in reducing the weight/volume ratio. On the other hand, the instability of the raw material market should be considered together with the location of Rare Earth materials in a few areas of the planet, with an expensive extraction process. For these reasons, recycling Neodymium-Iron-Boron magnets is considered a necessary and promising solution. Different techniques are available, but they are generally expensive or rather dangerous. Some methods to recover NdFeB powder from various devices are based on Hydrogen, such as Hydrogen decrepitation or hydrometallurgical methods, and alternatively chemical processes. This work proposes a new method based on a mechanical technique without using Hydrogen, resulting in a safer, less complicated and cheaper process. Based on the vacuum impact mill, the mechanical process of grinding the magnets recovered from hard disk drives has been tested. The obtained powder shows NdFeB magnetic characteristics and can be used again to produce permanent magnets
Impact of a Bonded-Magnet Adoption on a Specific Fractional Motor Power and Efficiency
No full textThe problem of evaluating the impact on the efficiency consequent to the adoption of bonded magnets in substitution of ferrites in small permanent-magnet machines is faced. That is necessary for the development of the main object of this paper: The evaluation of the obtainable performances of a specific brushless dc motor fractional motor through simple substitution of bonded magnets proposed by the authors to the ferrite magnets used up to now. The final aim is to make clear the practical adoptability of the proposal. Several prototypes produced in the authors' laboratories have been tested, and a long experimental activity has been carried on. In particular, the focus of the work has been the identification and separation of the iron losses, both hysteresis and eddy currents, from the contribution of the bearings. The corresponding torques have been calculated, and the energetic behaviors of the original machine with ferrites and the prototypes with phenolic bonded magnets have been analyzed. The satisfactory impact on the efficiency and the improvement of the output power of the motor with bonded magnets let possible to consider the analyzed solution as realistically adoptabl
Development of Halbach Array for Fractional Electrical Machine with Bonded Magnets
No full textThe magnetization of permanent magnets in electrical machines can improve performance, mainly if the Halbach array is used. This particular pattern is generally expensive and complicated to obtain. However, applying the NdFeB bonded magnets can provide a new solution for their versatility. In this context, the study of the Halbach array for the fractional motor has been conducted and compared with the radial magnetization. The first activity concerns designing the rotor geometry through finite element analysis. After that, the permanent magnet brushless motor has been equipped with prepared bonded magnets with the proposed Halbach array. The final comparison has been conducted through several experimental tests. The cogging torque, no-load voltage, iron losses, maximum torque, and efficiency have been examined to confirm the advantages of the proposed pattern
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