1,720,987 research outputs found
Bonded magnets for brushless fractional machines: Process parameters effects evaluation
No full textThe adoption of bonded magnets in substitution of ferrites in small PM motors is an interesting challenge and represents a good opportunity for motor designers. The proposed analysis regards the production of bonded magnets based on rare earth powder mixed with different resins; the effect of the process parameters, in particular the pressure on the mold, is evaluated by means of measurements on the magnets, FEM simulations and experimental tests on prototypes. The opportunity to vary also the resin percentage is briefly proposed as a glance on future developments of the work. © 2013 IEEE
Study of the Compositions of Hybrid Magnetic Composite (HMC) Materials for Sensor Applications
No full textThe research being carried out nowadays on soft magnetic materials focuses on increasing the total efficiency of electromagnetic devices reducing the total losses. In this context, new magnetic materials are becoming increasingly important and could replace the traditional ones in many applications. In the field of electrical machines and filter inductances, the laminated sheets could be replaced, for some applications, with more energy-efficient materials. New compacted magnetic cores have been implemented adopting Soft Magnetic Composite (SMC) materials. Many advantages are obtained by the use of such materials: lower eddy currents and total iron losses at medium frequencies and the possibility to produce magnetic cores in very complex geometries. In this work innovative SMCs are implemented using organic layers to insulate and keep together the grains; the effect of the particle sizes on magnetic properties has been examined: specimens with small, medium and big granulometry have been made and fully characterised
Pickup Magnetic Sensors: A Dedicated Simulation Tool to Evaluate Innovative Hybrid Materials
No full textMagnetic sensors are widely adopted in many industrial fields, particularly where the environmental conditions are difficult. A particular application, represented by a guitar pickup has been taken as reference to test innovative magnetic materials. The materials here proposed are Hybrid Magnetic Composites (HMC), obtained mixing together magnetic powder (Neodymium), a polymeric binder and a percentage of iron and then pressing in a mold. The resulting material presents a magnetic characteristic quite similar to those of AlNiCo, normally adopted in these kinds of pickup. In order to foresee the behavior of the sensor with a large number of possible materials, a dedicated simulation model has been realized; the simulation of the flux linkage in the coil, and the consequent induced voltage allows to compare the results and focus the attention on the most promising materials. AlNiCo, bonded magnets and HMC are compared in terms of performance. Contrarily to what can be imagined the materials with higher magnetic characteristics are not the best solution; particular attention has been in fact devoted to the evaluation of the attractive force between the magnets and the strings, that cannot be too high
Two approaches in the use of ferrites in assisted reluctance machines
No full textThe adoption of assisted reluctance machines in various applications is becoming popular. The use of permanent magnets in synchronous reluctance machines allows to resolve some drawbacks and improve the performance; in general, sintered magnets with regular shape have been adopted. On the other hand, this approach does not permit to fill completely the flux barriers. The proposed solution consists in the use of bonded magnets. Two types of ferrite magnets, sintered and bonded, have been considered in the study. Different parameters have been investigated, both in the production process and in the performance evaluation. The simulation results have been compared to the reference synchronous reluctance machines. A prototype machine has been prepared and different experimental tests have been performed. Good matching between measurement and simulation results has been observed
Different Approaches in the Use of Ferrites in Assisted Reluctance Machines
No full textThe adoption of assisted reluctance machines in various applications is becoming popular. The use of permanent magnets in synchronous reluctance machines solves some drawbacks and improves the performance; in general, sintered magnets with regular shapes have been adopted. On the other hand, this approach does not permit to fill completely the flux barriers. The proposed solution consists of the use of bonded magnets. Two types of ferrite magnets, sintered and bonded, have been considered in the study. Different parameters have been investigated, both in the production process and in the performance evaluation. The simulation results have been compared to the reference synchronous reluctance machines. A prototype machine has been prepared, and different experimental tests have been performed. Satisfactory matching between measurement and simulation results has been observed
Bonded Magnets in PM-Assisted Synchronous Reluctance Machines: Performance Dependence on the Production Technology
No full textThe versatility and robustness with the low costs, characterize the synchronous reluctance SRM machines. On the other hand, some drawbacks limit the potential of such machines. A solution was found in the use of permanent magnets in the flux barriers. The adoption of traditional regular sintered magnets does not allow a complete filling of the flux barriers, therefore the adoption of bonded magnets has been proposed, and two different production technologies have been analyzed. Three prototype machines have been prepared: Reference SRM and two PM-assisted reluctance. Interesting results have been obtained from experimental tests and compared to FE simulation ones
A Thermographic Method to Evaluate Different Processes and Assembly Effects on Magnetic Steels
No full textFerromagnetic materials may be affected by the presence of local losses due to defects or magnetic anomalies caused by machining processes. To highlight such anomalies is not easy; a noninvasive thermographic method has been refined to allow a proper comparison of different machining processes' impact on the iron losses. Specimens obtained with punching, wire erosion, and laser cut have been analyzed using a high-speed IR camera when subjected to alternate magnetization at different frequencies. Also, the same technique has been adopted to the assembled stacks to investigate more simultaneous phenomena. The possibility to point out localized anomalies should be exploited to foresee and avoid electrical machines core faults
A new soft magnetic composites material for electrical machine: Improvement of mechanical properties with high molding pressure
No full textSeveral developments concerning the electrical machines have been recently focused: new technologies and materials can improve the efficiency of the machines and of their production processes. With the availability of new magnetic materials, it is now possible to replace ferromagnetic laminated steels with Soft Magnetic Composites (SMC), opening to the possibility to obtain parts having shapes otherwise impossible and with better performances in medium and high frequencies. Some commercial products are available in the market, but with limited mechanical properties for the introduction in electrical machines. The will to improve the mechanical properties still retaining similar magnetic characteristics led the research activity to special iron powders and selected Epoxy and Phenolic resins as binders. The process has been improved investigating different molding pressures and different binder percentages. The results encourage to carry on the research exploring further improvements
Application of new magnetic materials for axial flux machine prototypes
No full textThe experience recently gained by the authors in the field of production and testing of new magnetic materials, especially developed for small electric machines, has been applied to the production of an axial flux permanent magnet motor prototype. In particular, different materials have been used for the stator and the rotor core, together with low-cost bonded permanent magnets; the machine under investigation is equipped with fractional slot windings and foils conductors insulated by a dedicated electro-deposition process. The design and the production of all the machine parts, as well as the experimental activities, have been performed and carried out by the research team at their Universities, without outsourcing needs. The design and FEM simulation results have been validated by means of comparison with experiments, obtaining good agreements
Overview on bonded magnets realization, characterization and adoption in prototypes
No full textIn the paper bonded magnets materials, their realization and adoption in electromechanical devices, are presented and evaluated. In particular the effects of different process parameters in their realization are deeply analyzed and described, supported by practical activities. Bonded magnets have been tested in various prototypes of rotating electrical machines and magnetic sensors; experimental results, comparing the performance of the devices equipped with these materials, with the original ones are presented. Furthermore a new magnetic material family is being explored, the Hybrid Magnetic Composites (HMC); they are prepared with both soft and hard magnetic powders, properly mixed with binders, and some examples of adoption in practical applications are proposed
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