Innovative Soft Magnetic Composite Materials: Evaluation of magnetic and mechanical properties

Electrical machines cover a very wide range of applications in many industrials sectors and the research to improve the performance of those applications is recently leading to the development of new solutions. Those devices are generally equipped with magnetic circuits made of laminated ferromagnetic steel, but in the last decade, new magnetic materials have been developed to realisemagnetic circuits: SoftMagnetic Composites (SMC). The Authors have investigated SMCs with organic layer obtained through the adoption of phenolic and epoxy resins; in previous research activities several mixture compositions have been produced and analysed with different percentages of binder and compacting pressures. Promising results regarding magnetic and mechanical performances have been obtained using a very low binder content. The paper aims to investigate the lower limit of the binder to be used, still keeping good mechanical properties. Appropriate magnetic tests have been performed on toroidal specimens: good magnetic characteristics have been obtained, maintaining on the other side proper mechanical strengt

Characterization of LPBF Produced Fe2.9wt.%Si for Electromagnetic Actuator

This study aims to produce Fe2.9wt.%Si ferromagnetic material via laser powder bed fusion (L-PBF) for the realization of electromagnetic actuators (EMA). This study is necessary as there are no documents in scientific literature regarding the manufacturing of Iron-Silicon plungers using the L-PBF additive manufacturing (AM) technique. The microstructure, and magnetic properties were characterized using various techniques. The results indicate that the samples produced via L-PBF process exhibit good magnetic properties (μ = 748, H C= 87.7 [A/m] ) especially after annealing treatment at 1200° C for 1h (μ = 3224, H C= 69.1 [A/m]), making it a promising material for use in electromagnetic actuators

Bonded magnets for brushless fractional machines: Process parameters effects evaluation

The 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

Pickup Magnetic Sensors: A Dedicated Simulation Tool to Evaluate Innovative Hybrid Materials

Magnetic 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

Study of the Compositions of Hybrid Magnetic Composite (HMC) Materials for Sensor Applications

The 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

Improvements in the Hysteresis and Cogging Evaluation with an Innovative Methodology

The paper presents an innovative methodology to detect the cogging and hysteresis torque in radial flux machines. The study moves from the traditional way adopted to measure them, that is by conventional no load tests; the experimental procedure here proposed is described in details, highlighting the advantages with respect to the previous method. A cheaper test bench is needed, as the gearbox is avoided, and a stepper motor in place of a DC motor is adopted to move the system. The procedure has been tested on two identical machine structures, but with different stator materials (traditional laminated steel and Soft Magnetic Composite material); a comparison with the results obtained with traditional no load tests has been performed to validate the proposed procedure. The novel method is more accurate in the detection of the cogging torque, even if requires a measurement time slightly longer (about 30 minutes of duration)

Two approaches in the use of ferrites in assisted reluctance machines

The 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

The 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

A new soft magnetic composites material for electrical machine: Improvement of mechanical properties with high molding pressure

Several 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