Ferrite Magnets Research Articles

Subdomain modeling of linear hybrid excited flux switching machine

PurposeThis paper aims to develop an analytical approach to validate the finite element analysis (FEA) results. FEA itself is a powerful tool to evaluate the performance of electrical machines but takes more time and requires more drive storage. To overcome this issue, subdomain modeling (SDM) is used for the proposed machine.Design/methodology/approachSDM is developed to validate the electromagnetic performance of a new linear hybrid excited flux switching machine (LHEFSM) with ferrite magnets. In SDM, the problem is divided into different physical regions called subdomains. Maxwell's governing equation is solved analytically for each region, where the magnetic flux density (MFD) is generated. From the generated MFD, x and y components are calculated, which are then used to find the useful force along the x-axis.FindingsFEA validates the developed SDM via JMAG v. 20.1. The results obtained show excellent agreement with an accuracy of 95.13%.Practical implicationsThe proposed LHEFSM is developed for long stroke applications like electric trains.Originality/valueThe proposed LHEFSM uses low-cost ferrite magnets with DC excitation, which offers better flux regulation capability with improved electromagnetic performance. Moreover, the developed SDM reduces drive storage and computational time by modeling different parts of the machine.

Design and Analysis of a High Torque Density Hybrid Permanent Magnet Excited Vernier Machine

Permanent magnet (PM) excited vernier machines capable of high torque density have good potential for electric vehicles while requiring high rare earth PM consumption. To achieve a high torque density at a reasonable material cost, hybrid PM excited vernier machines incorporating both expensive rare earth and low-cost ferrite magnets are investigated in this paper. Various combinations of PM arrangements for the hybrid permanent magnet excited vernier machine are investigated to acquire low cost and superior torque density. The best solution obtained is that the PM on the stator adopts rare earth material while the rotor uses ferrite. Furthermore, the PMs on the stator are arranged in an iron-cored Halbach array, which can reduce leakage flux and enhance flux density effectively and the ferrite PMs are used in the rotor, therefore, high-temperature demagnetization is avoided. Then, the reluctance torque and the cogging torque can offset each other effectively, which is beneficial to reducing the torque ripple and smoothing the electromagnetic torque. Finally, a prototype is manufactured and tested to verify the correctness of the theoretical analysis.

Analysis of Linear Hybrid Excited Flux Switching Machines with Low-Cost Ferrite Magnets

Linear hybrid excited flux switching machines (LHEFSM) combine the features of permanent magnet flux switching machines (PMFSM) and field excited flux switching machines (FEFSM). Because of the widespread usage of rare-earth PM materials, their costs are steadily rising. This study proposes an LHEFSM, a dual stator LHEFSM (DSLHEFSM), and a dual mover LHEFSM (DMLHEFSM) to solve this issue. The employment of ferrite magnets rather than rare-earth PM in these suggested designs is significant. Compared to traditional designs, the proposed designs feature greater thrust force, power density, reduced normal force, and a 25% decrease in PM volume. A yokeless primary structure was used in a DSLHEFSM to minimize the volume of the mover, increasing the thrust force density. In DMLHELFSM, on the other hand, a yokeless secondary structure was used to lower the secondary volume and the machine’s total cost. Single variable optimization was used to optimize all of the proposed designs. By completing a 3D study, the electromagnetic performances acquired from the 2D analysis were confirmed. Compared to conventional designs, the average thrust force in LHEFSM, DSLHEFSM, and DMLHEFSM was enhanced by 15%, 16.8%, and 15.6%, respectively. Overall, the presented machines had a high thrust force density, a high-power density, a high no-load electromotive force, and a low normal force, allowing them to be used in long-stroke applications.

Influence of Bi3+ ions substitution on structural, magnetic, and electrical properties of lead hexaferrite

The Microwave induced sol-gel auto-combustion process was used to make lead hexaferrite, PbFe12-xBixO19 (x=0.2 to 0.8), with Bi3+ as a replacement. X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), vibrating sample Magnetometry (VSM), Fourier transform infrared spectroscopy (FT-IR), and Impedance analysis was used to test the impact of added Bi3+ ions on the structure, morphology, magnetic, and dielectric properties of lead hexaferrite. Single-phase hexagonal ferrite nanoparticles with average crystalline sizes of 43 to 59 nm were achieved with the space group of P63/mmc. The magnetic analysis revealed that when the Bi3+ ion is supplemented in the Pb ferrite,the coercive and saturation magnetization of the material was amplified. The substance's dielectric constant, electric conductivity, and loss tangent were calculated for frequencies of 20 Hz to 10 MHz, indicating that it is appropriate for wide applications like permanent magnets, high-density magnetic recording media.

A New IPMSM With Hybrid Rotor Structure for Electrical Vehicle With Reduced Magnet Loss

Aiming at the problem of excessive eddy current loss of permanent magnets in fractional slot concentrated winding permanent magnet synchronous motors (FSCW-PMSM) at high speed, a new PMSM with hybrid rotor structure for electric vehicles (EV) is proposed in the article, the key is to introduce additional ferrite magnets in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula> - and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q$ </tex-math></inline-formula> -axis magnetic flux paths, respectively. Furthermore, slotting on the rotor surface and genetic algorithm (GA) optimization are adopted to compensate for the side effects caused by the introduction of ferrite magnets and to obtain optimal parameters of the new motor. Compared with the traditional all-Nd-Fe-B structure, the proposed hybrid rotor structure can not only curb the magnet loss at high speed, but also present a cost-effective design approach for interior pemanent magnet synchronous motor (IPMSM) for EV applications with less usage of expensive Nd-Fe-B magnets as well as enhanced reluctance torque capability.

Effect of Ferrite as Filler in Sugarcane Bagasse Paper via Irradiation Method

Deforestation issues increased dramatically every year specially to produce paper. Therefore, to supplement the limited wood fibre resources, non-wood fibres especially sugarcane bagasse introduced an alternatives resolve for raw material is considered in paper-based industries. This study addresses the analysis of magnetic sugarcane bagasse materials as substitute fibres in papermaking. Paper is generally made with cellulose fibre which has some specific features used for educational, packaging, and cleaning purposes. Sugarcane bagasse (Saccarhumofficinarum) is popular for its cellulose, holocellulose, and lignin that far more convenient than wood fibres. Meanwhile, the demands of magnetic material in magnetic papermaking industry has increased due to its excellent mechanical characteristics. As the magnetic paper shows some superiority in properties such as renewable use and folding resistance. The used of filler in this study is to alter the properties such as texture, opacity, brightness, dimensional stability, and overall printability. Thus, the used of ferrite (Fe) magnet as a filler can enhance the paper properties. Ferrite is recognized as a hard-magnetic material with distinct properties such as good mechanical hardness and chemical stability, therefore it is a much more convenient material for magnetic paper production. Through the observation under Scanning Electron Microscope (SEM), the image obtained shows that magnetics sugarcane bagasse paper was more convenient to be used as an alternative for paper making. Next, Fourier-Transform Infrared Spectroscopy (FTIR) recognizes the presence of a functional group of the magnetics sugarcane bagasse paper. Moreover, the chemical properties obtained from this study show that the magnetics sugarcane bagasse was as good as the commercial paper available in the industries. To increase the integrity of the paper, the radiation process by using gamma-ray was done to the paper to see the different for pre and post radiation.

Nb5+ ion substitution assisted the magnetic and gyromagnetic properties of NiCuZn ferrite for high frequency LTCC devices

Nowadays, developing nickle zinc ferrites with excellent magnetic and gyromagnetic properties are of great importance for solving the matching problem of 5G communication system. However, much is discussed about soft magnetic properties, but little is reported gyromagnetic properties that is critical for microwave device applications. Herein, Nb5+ ions substituted Ni0.29Cu0.18Zn0.53NbxFe2-xO4 (x = 0.00-0.05), possessing high saturation magnetization, approriate initial permeability, high cut-off frequency and low ferromagnetic resonance linewidth (@9.55 GHz), were synthesized by low-temperature firing (900 °C). The phase structure and morphology evolutions were studied in detail. The results of morphology observations revealed that Nb5+ substitution has significant role in determining produce compact and uniform microstructures of NiCuZn ferrites via suppress the grain growth, which further corresponding enhance the magnetic and gyromagnetic properties. As a result, a uniform and compact grain size can be obtained, corresponding to the change of magnetic and gyromagenetic properties have different trends. Enhanced magnetic and gyromagnetic performance including high initial permeability (μ' = 203 @1 MHz), saturation magnetization (4πMs = 3966 Gauss) and low ferromagnetic resonance linewidth (ΔH = 203 Oe) of the NiCuZn ferrites is achieved though adjusting Nb5+ ions substitution. More importantly, this work not only for low temperature co-fired ceramic (LTCC) technology but also for high frequency and microwave frequency devices including phase shifter and radars.

Enhancing magnetism of ferrite via regulation of Ca out of sit A from spinel-type structure by adjusting the CaO/SiO2 mass ratio: Clean and value-added utilization of minerals

Ferrites with a typical AB2O4 structure are excellent soft magnetic material precursors. One progress for preparation of manganese ferrite is to use the minerals as raw materials. However, the inclusive impurities, such as Ca and Si, may dope in the AB2O4 structure and have an adverse effect on the magnetism of ferrites. In this work, the effects of CaO and SiO2 on the crystalline structure transformation, interfacial elements distribution, and magnetism change of the MnO2-Fe2O3-CaO-SiO2 system for preparation of high-performance ferrite materials were systematically investigated. It's found that Ca ions can readily be doped in the sit A of spinel-type structure to form CaaMnbFe2O4, and the magnetism of manganese ferrite was observably declined due to the Ca doping. A diffusion couple of synthetic CaaMnbFe2O4 and SiO2 was designed to determine the Ca migration. Results demonstrated that regulation of Ca out of sit A from the spinel-type structure can be successfully realized via adjusting the CaO/(CaO ​+ ​SiO2) mass ratio below 0.55, and the magnetism of ferrite after Ca migration was obviously enhanced. The migrated CaO combined with SiO2 to form calcium silicate which was distributed at the boundaries of ferrite particles. Eventually, the verification test of low-grade manganese ores with CaO and SiO2 impurities was conducted to validate the Ca migration effect.

Analytical Investigation and Heuristic Optimization of Surface Mounted Permanent Magnet Machines With Hybrid Magnetic Structure

Cogging torque causes major operational setbacks for Permanent Magnet (PM) machine operation, particularly in applications where a quiet performance is desired. This paper presents a heuristic optimization framework to optimize the cogging torque in Surface Mounted Permanent Magnet (SPM) machines consisting of a hybrid magnetic structure (i.e., rare-earth and ferrite magnets). To avoid excessive computational time and volume associated with Finite Element (FE)-based optimization solutions, analytical approach is paired up with the optimization algorithm to determine the optimal design while FE is utilized for verification and validation purposes. First, analytical expressions are established for individual objective functions (i.e., airgap PM flux distribution, and cogging torque), and their corresponding spatial harmonics are identified using the air-gap field modulation theory. Next, the presented analytical model is utilized to optimize the system (i.e., minimize the cogging torque) to the desired target level via two different solutions (i.e., Genetic Algorithm (GA) and Particle Swarm Optimization (PSO)), and their respective performance are compared. To determine the efficacy of the presented solutions, the optimal hybrid machine response is compared against the baseline structure.

The Demagnetization Processes of Nd-Fe-B Sintered Magnets and Ferrite Magnets as Demonstrated by Soft X-Ray Magnetic Circular Dichroism Microscopy

The Demagnetization Processes of Nd-Fe-B Sintered Magnets and Ferrite Magnets as Demonstrated by Soft X-Ray Magnetic Circular Dichroism Microscopy

Comparative analysis of Synchronous Reluctance Motor with different Permanent Magnet materials

Permanent Magnet Assisted Synchronous Reluctance (PMASR) motors are considered as alternate to traditional induction motors and synchronous reluctance motors owing to its improved power factor, efficiency, reduced ripple torque and high torque density. The applications which employ this type of motor includes pumps, fans, compressors, conveyors and mixers. The aim of this work is to study on effect of PMASR motors with NdFeB magnets along with ferrite magnets and conventional Synchronous Reluctance motor with respect to torque performance, size, efficiency, cost and Von-Mises stress performance. The parameter varied in this work is stack length with fixed diameter therefore adopting a uniform stator design and winding scheme. The results of this work provides insight into the various performance measures with choice of different magnets.

Influence of Zero-Sequence Circulating Current on the Performance of Star-Delta Winding Line-Start Ferrite Assisted Synchronous Reluctance Motor.

To meet the new international efficiency (IE) standards, line-start (LS) synchronous reluctance motors (SyRMs) are now being considered. Conventional star and delta windings are usually employed in LS SyRMs. However, combined star-delta winding has higher winding factor and lower magneto-motive force (mmf) harmonics compared to conventional star and delta windings. Hence, in this paper, LS SyRM and LS ferrite assisted SyRM with star and star-delta winding are analyzed and their performance indices are compared. A winding function analysis is used for the design of star and star-delta windings. Further, the effect of zero sequence current on the performance of the motors under comparison is presented in detail. Star and star-delta winding prototype LS SyRMs with and without ferrite magnets in the rotor are fabricated. Experimental studies are carried-out on these prototypes and the results are presented which are in close agreement with the simulation results.

Combined characterization approaches to investigate magnetostructural effects in exchange-spring ferrite nanocomposite magnets

Combining multiple characterization probes (neutrons, X-rays, electrons) illustrated the hierarchical structure of exchange-spring nanocomposites &amp; revealed unreported degradation of parent phase.

Performance analysis and comparison of PM-Assisted synchronous reluctance motor with ferrites and Rare-earth magnet materials

The paper aims to provide appropriate design methodology for chosen suitable permanent magnet material to be applied in manufacturing the Permanent Magnet (PM) assisted synchronous reluctance motor (PMASyRM). Another purpose is to reduce the use of rare earth magnets in motor design and increase the use of ferrite magnets to achieve the best performance of the motor. The performance analysis of the motor is discussed with different PM materials volume or quantity. The tradeoff design is presented to achieve the best performance parameter i.e. high torque, efficiency, and low torque ripple. The effect of a combination of different PM materials on the performance parameters of the motor is analyzed.

Effects of Ni2+ concentration on the composition, structure, magnetic properties, and DC-bias superposition characteristics of NiCuZn ferrites

NixCu0.2ZnyFe1.98O4 (x = 0.16, 0.26, 0.35, 0.43, 0.50; y = 0.8−x) ferrites were prepared via solid-state reaction. The influence of Ni2+ concentration on ferrites composition, microstructure, magnetic properties and DC-bias superposition characteristics was studied by XRD, SEM, XPS, and VSM. Then, the effect of magnetic properties on the DC-bias superposition characteristics was analyzed. The results showed that the ferrites sintered at 900 °C for 3 h were all in pure spinel phase with an average grain size of 7.5 μm and a relative density of about 5.15 g cm−3. With the increase in Ni2+ concentration, the saturation magnetization (Ms) and coercivity (Hc) of ferrites increased, but the magnetocrystalline anisotropy constant (K1) first increased and then decreased. And the Ms, Hc, and K1 of the specimen with x = 0.43 were 63.62 emu·g−1, 27.36 Oe, and 1813.17 Oe·emu·g−1, respectively. In particular, the specimen of x = 0.50 achieved the best DC superposition characteristics, where the H70% was about 220 A m−1. The incremental permeability of the specimens decreased rapidly at a bias magnetic field <400 A m−1. The variation mainly originated from the domain wall displacement, and the rate of decrease was influenced by both Ms and K1. At a bias magnetic field ≥400 A m−1, the incremental permeability of the specimens decreased slowly, mainly because the number of domain walls decreased until disappearing, and the specimens tended to become a single domain structure. And the rate of decrease of incremental permeability was mainly affected by K1.

Lightweight Low‐Noise Linear Isolator Integrating Phase‐ and Amplitude‐Engineered Temporal Loops

AbstractThe quest for efficient and versatile microwave and optical isolators has recently led to spawn space–time‐modulated isolator structures. However, such space‐time isolators suffer from a large profile and complex architecture that is required for a progressive nonreciprocal space–time coupling. To overcome these limitations, here a nonmagnetic phase‐engineered temporal loop‐based isolator featuring large isolation levels, suppressed undesired time harmonics while exhibiting a low profile is proposed. The proposed isolator is composed of two temporal loops that provide desired constructive and destructive interferences of different time harmonics. Furthermore, these two loops are designed in a way to assure that the circulation and reflection of different time harmonics strengthen a unidirectional signal transmission with low insertion loss. An experimental demonstration of the proposed time‐modulated isolator is provided at microwave frequencies, featuring strong unidirectional wave transmission through the isolator with more than 27 dB contrast between the forward and backward waves, across a fractional bandwidth of 14.3%. The proposed technique outperforms alternative approaches, that is, space–time modulation, ferrite magnets, nonlinearity, and HBT/CMOS transistors. It features a highly linear response with OP1dB of higher than 31 dBm, high power rating of more than 47 dBm, and a low noise figure of 3.4 dB.

Design and Thermal Modeling of Modular Hybrid Excited Double-Sided Linear Flux Switching Machine

This paper presents a Hybrid Excited Double-Sided Linear Flux Switching Machine (HEDSLFSM) with a crooked tooth modular stator. Generally, the conventional stators are made of a full-length iron core, increasing manufacturing costs and iron losses. Higher iron losses result in lower efficiency and lower overall performance. A U-shaped modular stator with a crooked tooth is used to lower iron consumption and increase the machine’s efficiency. Ferrite magnets are used to replace rare earth magnets, which also reduces the machine cost. Two DC excitation windings are used above and below the ferrite magnet to reduce the PM volume. 2D electromagnetic performance analysis is done to observe the key performance indices. Geometric optimization is used to optimize the Split Ratio (S.R), DC winding slot area (DCw), and AC winding slot area (ACw). Stator Tooth Width (STW), space between the modules (S.S.), and crooked angle (α) are optimized through JMAG in-built Genetic Algorithm (G.A.) optimization. High thrust force density and modular stator make it a good candidate for long-stroke applications like railway transits. The thermal analysis of the machine is performed by FEA analysis and then validated by 2D LPMC (Lumped Parametric Magnetic Equivalent Circuit) model. Both analyses are compared, and an error percentage of less than 4% is achieved.

High-spatial-resolution measurement of magnetization distribution using polarized neutron imaging

The evaluation of the magnetization distribution inside a bulk magnet is important for ensuring the performance of automotive motors because it strongly depends on the quality of magnetization inside the permanent magnet. In the conventional destructive method, it is difficult to accurately measure the magnetization with a high spatial resolution. The polarized neutron imaging technique can be used to visualize the distribution of the magnetic flux density inside a magnet nondestructively. In this study, we demonstrated the imaging of the magnetization distribution using polarized neutrons in an anisotropic ferrite magnet sample. The 2D distribution of the magnetization was experimentally obtained by polarized neutron imaging with a high spatial resolution of less than 1 mm. Furthermore, the validity of the results was confirmed by comparing them with those obtained using the conventional destructive method.

Effect of organic solvent on the cold sintering processing of SrFe12O19 platelet-based permanent magnets

In this work we have investigated the effect of the solvent during the processing of SrFe12O19 platelet-based permanent magnets by cold sintering process (CSP) plus a post-thermal treatment. Several organic solvents: glacial acetic acid, oleic acid and oleylamine have been analyzed, optimizing the CSP temperatures at 190−270 °C, under pressures of 375−670 MPa and 6−50 wt% of solvent. Modifications in the morphological and structural properties are identified depending on the solvent, which impacts on the magnetic response. Independently of the solvent, the mechanical integrity of ferrite magnets obtained by CSP is improved by a post-annealing at 1100 °C for 2 h, resulting in relative densities around 92 % with an average grain size of 1 μm and a fraction of SrFe12O19 phase >91 %. HC ≥ 2.1 kOe and MS of 73 emu/g are obtained in the final sintered ceramic magnets, exhibiting the highest HC value of 2.8 kOe for the magnet sintered using glacial acetic acid.

Preparation and magnetic properties of lanthanum- and cobalt-substituted M-type Sr base sintered magnets

In this work, the influence of the time points of the simultaneous or separate partial substitution of La3+ for Sr2+ and of Co2+ for Fe3+ in Sr ferrite on the magnetic properties of anisotropic M-type Sr ferrite magnets was investigated. It was found that the optimum values of the remanence B r and of the coercivity H ci of Sr ferrite magnet were obtained by La–Co simultaneous substitution before calcination. On the other hand, H ci is increased causing a minor decrease in B r by La separate substitution before calcination and Co separate substitution after calcination. Whereas, La–Co simultaneous substitution after calcination has a deteriorating effect on the B r of M-type Sr ferrite. Optimum magnetic properties and conditions in the experiment will eventually be used as high-end permanent magnets for the high-efficiency motor application in automobiles with B r > 4500 ± 50 Gauss and H ci > 4500 ± 50 Oe.