Flux Path Research Articles

Finite element analysis and design of a magnetostrictive material based vibration energy harvester with a magnetic flux path

Abstract This work presents the development of a nonlinear 2D finite element (FE) framework for magnetostrictive material based energy harvesters of beam geometry. The FE model is developed in COMSOL Multiphysics and compared with existing literature for validation. The FE model is subsequently used to study the effect of a closed magnetic flux path, consisting of ferromagnetic components, on the harvester output. Specifically, the voltage output is obtained by performing simulations on unimorph type harvester devices with and without a closed magnetic flux path, both operating at the same natural frequency and volume of the magnetostrictive material Galfenol. The harvester design considered here consists of a magnetostrictive layer (Galfenol) bonded to a steel substrate layer, a tip mass, a pick-up coil and a magnetic flux path consisting of soft iron core and NdFeB permanent magnets. Our results demonstrate a voltage gain of around 70% for the closed flux path design. Furthermore, a proof of concept prototype of the modified flux path design is developed, tested under impulse loading, and the voltage, power output are compared with FE simulation results for validation. The simulation results match well with experimental observations at two operating frequencies for the flux path design.

Research on magnetic nonchain transport of steel cartridge casing ammunition

Magnetic force is used to drive ferromagnetic objects by shortening the magnetic flux path to reduce magnetic reluctance and increase magnetic conductivity. Based on this characteristic, magnetic force drives have been widely applied in various fields, such as military, transportation, and engineering, attracting significant attention. This paper proposes a method for the nonchain transport of steel shell ammunition based on magnetic force. The force generated by the minimal magnetic resistance in the air gap is utilized to drive the steel shell ammunition. A calculation model for the driving component is proposed using the Maxwell stress tensor method, and the accuracy of the model is verified by simulating ammunition motion curves using finite element software. Finally, prototype experiments are conducted to explore the motion conditions under uncertain ammunition masses. The magnetic nonchain ammunition transport mechanism features a simpler structure and lower maintenance costs, making it more suitable for use on unmanned platforms.

Power enhancement of vibration energy harvesters by way of magnetic flux gradient analysis of electromagnetic induction

This study proposes strategies to enhance the conversion of mechanical energy to electrical energy in cylindrical electromagnetic induction-type vibration energy harvesters (VEH) using disc or ring-shaped magnets and ring-shaped coils. The rationale behind these strategies has been substantiated by an analysis of magnetic flux gradients based on simulations. In particular, the utilization of a repulsive magnet pair and a yoke has been proposed to maximize the magnetic flux gradient at the coil winding position by manipulating the magnetic flux path. Simulation results confirm that the use of a yoke can produce a nearly 5.8-fold increase in power consumption at the external load. Additionally, the study demonstrates that the positioning and thickness settings of the coil are critical for improving the electrical output based on the spatial distribution of the magnetic flux gradient. Within the same magnet topology, points where power generation is not feasible due to a zero magnetic flux gradient are identified, besides a nearly 5.3-fold increase in observed power generation depending on coil placement. Given the structural feasibility of VEH implementation, a design for a moving magnet VEH utilizing ring magnets with a yoke enclosure is proposed, demonstrating that it can generate power at nearly 85% of the level attributed to using disc magnets.

Determining photon flux and effective optical path length in intensified flow photoreactors

Determining photon flux and effective optical path length in intensified flow photoreactors

Introducing a 12/10 Induction Switched Reluctance Machine (ISRM) for Electric Powertrains

The induction switched reluctance machine (ISRM) is a novel electric machine that integrates the switched reluctance machine (SRM) with rotor inductive conductors to enhance performance in electric vehicle (EV) powertrain applications. In this topology, the rotor conductors act as a magnetic shield, diverting magnetic flux and preventing magnetic field lines from penetrating the rotor body. By engineering this design, short magnetic flux paths are created in both the stator and rotor of the electric machine. Since its recent introduction, the ISRM represents an emerging technology in the early stages of development. Similar to conventional SRMs, the ISRM can take on various topologies with different stator and rotor pole numbers. Minimizing rotor copper loss is a critical consideration in the ISRM design process. This paper examines two distinct ISRM topologies (12/10 and 12/8), and their characteristics are analyzed using the finite element method. Simulation results, including power density, torque density, efficiency, and copper loss, are presented and compared. Finally, the optimal ISRM topology is proposed for hybrid electric powertrains.

Enhanced Magnetoimpedance Effect in Co-Based Micron Composite CoFeNiSiB Ribbon Strips Coated by Carbon and FeCoGa Nanofilms for Sensing Applications.

Quenched Co-based ribbon strips are widely used in the fields of magnetic amplifier, magnetic head material, magnetic shield, electric reactor, inductance core, sensor core, anti-theft system label, and so on. In this study, Co-based composite CoFeNiSiB ribbon strips with a micron width were fabricated by micro-electro-mechanical systems (MEMS) technology. The carbon and FeCoGa nanofilms were deposited for surface modification. The effect of carbon and FeCoGa nanofilm coatings on the crystal structure, surface morphology, magnetic properties, and magnetoimpedance (MI) effect of composite ribbon strips were systematically investigated. The results show that the surface roughness and coercivity of the composite ribbon strips are minimum at a thickness of the carbon coating of 60 nm. The maximum value of MI effect is 41% at 2 MHz, which is approximately 2.4 times greater than plain ribbon and 1.6 times greater than FeCoGa-coated composite ribbon strip. The addition of a carbon layer provides a conductive path for high frequency currents, which effectively reduces the characteristic frequency of the composite ribbon strip. The FeCoGa coating is able to close the flux path and reduce the coercivity, which, in turn, increases the transverse permeability and improves the MI effect. The findings indicate that a successful combination of carbon layer and magnetostrictive FeCoGa nanofilm layer can improve the MI effect and magnetic field sensitivity of the ribbon strips, demonstrating the potential of the composite strips for local and micro area field sensing applications.

Performance Analysis of a Novel Axial Radial Flux Segmental Rotor Switched Reluctance Motor

Based on the characteristics of axial flux switched reluctance motor (SRM) and radial flux SRM, this paper proposes a new type of axial radial flux segmental rotor switched reluctance motor (ARFSRSRM). The motor has the left and right dual axial stator structures, which forms a kind of axial flux path with the segmental rotor in the middle, and a radial stator structure, which shares a kind of radial flux path with the segmental rotor on the outside of the motor. Compared with the conventional SRM, this motor combines the advantages of high output torque and torque density due to the inclusion of two kinds of flux paths, making it suitable for high-efficiency and high-torque fields such as electric vehicles. In this paper, the topology and operating principle of the new motor are first introduced. Then the initial structural parameters are derived, and the multi-objective optimization of the proposed motor is carried out using Taguchi’s algorithm. The static and dynamic performance of the motor is comprehensively analyzed using the 3-D finite element method. Finally, the experimental results obtained through the trial production of a prototype machine verify the good performance of the new motor.

Magnetic Flux Paths in Single Sheet Tester as Modeled Numerically

Magnetic Flux Paths in Single Sheet Tester as Modeled Numerically

Design of an Integrated Magnetorheological Fluid Brake Axial Flux Permanent Magnet Machine

This paper presents the design and performance of an integrated magnetorheological fluid brake axial flux permanent magnet (IMRFB-AFPM) machine with two switchable operation modes: rotation and brake modes while the machine has two kinds of windings: armature winding in axial stators and braking winding in radial stator. In rotation mode, this machine is equal to a conventional AFPM machine with high torque density. When switching to brake mode, MR fluid is excited by braking winding and applies large damping stress to the rotor to brake it. This paper illustrates the machine topology, operation principles, and design flow of the proposed machine. Then, this paper analyzes the torque generation mechanism in two modes and applies parameters optimization to improve the torque capability of each mode. Due to the independence of the magnetic flux path, the parameters optimization is divided into two parts: AFPM part and IMRFB part. After the optimization process, the electromagnetic performances of the optimal IMRFB-AFPM machine are analyzed by finite element (FE) analysis. Finally, a prototype machine with the optimal geometric parameters is manufactured and verified experimentally. The experiment results agree well with FE analysis results, validating the feasibility and practicability of the proposed design.

D-Q Axis Inductance Analytical Calculation for Fractional-Slot Distributed Winding IPM Motor Based on Big-Small Pole Space Method

The d-q axis inductance is the crucial parameter for the interior permanent magnet (IPM) motor. In order to facilitate the design, analysis, and optimization of IPM motors, it is of great significance to develop an accurate and simplified inductance analytical calculation method. Among the existing calculation methods, the magnetic equivalent circuit (MEC) has advantages in the inductance calculation of the IPM motor due to the simple modeling, the fine processing of the saturation region and the visualization of the magnetic field distribution. However, the traditional MEC method is only applicable to the IPM motor with integer-slot distributed winding (ISDW) or fractional-slot concentrated winding (FSCW), while lacking of in-depth research on fractional-slot distributed winding (FSDW). The magnetic circuit topology of FSDW IPM motors is not as single as that of FSCW/ISDW IPM motors. It leads to problems in the traditional MEC method when dividing the d/q axis flux path in FSDW motors. To solve this problem and expand the applications of MEC method, a big-small pole space (BSPS) method is proposed after fully considering the common characteristics of MMF distribution and reluctance distribution in FSDW motors, which fills the gap of MEC method applied to FSDW motors. The BSPS method divides the d-axis flux path according to the asymmetry of the d-axis magnetomotive force (MMF). Based on the divided flux paths, an improved nonlinear MEC model that considers the saturation of stator and rotor is established to calculate d- and q-axis inductances. The results of finite element analysis (FEA) verify the validity of the proposed MEC model with different geometry parameters. Experimental results of an 84-pole/360-slot FSDW I-type IPM wind generator further confirm the validity of the proposed MEC model

Optical wave propagation phase for mKdV spherical electric flux density in sphere space

In this article, we illustrate surface flow alfa-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$alfa-$$\\end{document} microfluidical mKdV spherical electromotive phase in sphere space. Also, we obtain antiferromagnetic axially electrical alfa-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$alfa-$$\\end{document}microfluidical mKdV electric flux path circuit. We have electrical alfa-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$alfa-$$\\end{document}microfluidical geometrical mKdV free surface flow density in sphere space. Finally, we design antiferromagnetic wave propagation for alfa-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$alfa-$$\\end{document} microfluidical geometric mKdV surface flux density.

A development of mobile application satellite link budget calculator – SATELEC

Link Budget is a calculation of gains and losses during transmission from transmitter to receiver in each communication system. In satellite communication, the main purpose of calculating link budget is to analyse the satellite system performance. One of the parameters to measure the satellite link performance is the Carrier to Noise ratio (C/N). There are a few satellite link calculators were developed using MATLAB/GUI and website. However, there are no available apps to help student to compare the calculated satellite link budget calculator for self-study. Therefore, a mobile apps called SATELEC was developed to calculate satellite link budget parameters. By using this satellite link budget calculator apps, all parameters such as Effective Isotropic Radiated Power (EIRP), Power Flux Density, Path Loss, Antenna Gain and Power Received can be calculated. After the value of power received is obtained, the value of Carrier to Noise ratio (C/N) can be determined by taking into account the noise in the communication. Results shows values obtained from the mobile is reliable after comparison with calculated value.

A Novel Integrated OBC and LDC System with Flux Path Reconfiguration for Electric Vehicles

A Novel Integrated OBC and LDC System with Flux Path Reconfiguration for Electric Vehicles

Modified Induction Machine Equivalent Circuit Including Solid Shaft Eddy Currents

The shaft eddy currents cause a significant saturation in two-pole induction machines (IMs) as they generate an opposing field and repulse the main flux, thus tightening the flux path. This results in inaccurate performance estimations with the magnetizing inductance measured in no-load conditions when the machine is loaded. This article presents a modified IM equivalent circuit considering the rotor back iron saturation effects caused by the solid shaft eddy currents using experimental measurements and recursive parameter estimation techniques. The classical equivalent circuit (CEC) parameters are determined with the standard test techniques followed by the parameter estimation of the newly introduced modified equivalent circuit (MEC) parameters. The proposed modified equivalent circuit is benchmarked with CEC and finite element analysis (FEA) simulations with and without considering eddy effects. The proposed MEC model and the FEA that consider eddy effects performed better than the other models and yielded a negligibly small error over a wide range of loading conditions. Compared to the FEA, the proposed MEC estimates the IM performance much faster, which makes it more appealing for IM performance estimations.

Characterization of an Axial Flux Machine With an Additively Manufactured Stator

Axial flux machines (AFM) are promising alternatives to radial flux machines for applications that benefit from high torque density and a large diameter to axial length ratio, such as in-wheel traction motors. However, the 3D flux paths in AFM present unique challenges to manufacturing laminated stator cores. This paper positions metal additive manufacturing (AM) technology as a potential solution to manufacture unconventional electric machine components such as AFM stators by investigating novel lamination emulating geometric structures and material silicon composition as design handles. In this paper, techniques to additively manufacture soft magnetic components for rotating electric machines are reviewed, and the Hilbert pattern is identified as a promising candidate to reduce eddy-current losses in these components. To further reduce the eddy current losses, this paper investigates the use of 6.5% silicon steel, which has higher resistivity compared to conventional steel laminations. The results in this paper show that the Hilbert structure is effective in reducing the eddy current losses by 50% compared to a solid structure with 3% silicon steel, and using 6.5% silicon steel further reduces the eddy current losses by 24%. Finally, a candidate AFM stator is designed with the Hilbert pattern and fabricated additively using 6.5% silicon steel. This machine is characterized and experimentally compared with an identical axial flux machine that uses a laminated stator. The results demonstrate the potential of metal AM technology to fabricate electric machine components with eddy current losses comparable to ultra-thin gauge laminations at frequencies up to 200Hz and conventional 29Ga laminations up to 480Hz.

Design and Optimization of a Partitioned Stator Hybrid Excited Machine With Inset PM From Perspective of Airgap Field Harmonics

In this paper, a novel partitioned stator hybrid excited machine with inset permanent magnet is proposed, which offers reduced flux leakage of permanent magnet and parallel flux paths. Also, the partitioned stator is introduced to alleviate the space conflict between multiple excitation sources. Thus, its torque and flux regulation capability can be improved. In order to understand the hybrid excited principle and improve the electromagnetic performances, the machine is analyzed and optimized from perspective of airgap field harmonics. First, airgap field harmonics produced by field modulation effect of the machine are analyzed and calculated by equivalent airgap model. Then, an optimization method based on airgap field harmonics is proposed and implemented to improve its electromagnetic performances. Finally, the machine design and optimization method are evaluated and verified by both finite element analysis and prototype experiments.

Prediction of thermal conduction in a four-phase composite with lowly-conducting interfaces based on variational asymptotic method

Due to the complex physical and chemical reactions, surface contamination and debonding, the interfaces within the four-phase composite, represented by hollow-glass-bead reinforced cement based material (HGB-CBM), cannot be assumed to be perfect. In order to consider the effect of imperfect interfaces, a novel thermal conduct model is developed. An imperfect interface is used to replace the pre-existing transition layer in the composite material, and the discontinuous temperature field proportional to the normal heat flow is preserved by using Hadamard’s relation and Taylor’s expansion. Based on the principle of minimum functional and variational asymptotic method, the governing variational statement for thermal conduct model is derived, and validated through comparison with RVE-based FEM and experimental results. It can be concluded that HGB-CBM with lowly-conducting imperfect interfaces has lower effective thermal conductivity, smaller heat flux within HGB and more significant changes at imperfect interfaces, which may be due to longer and more complex heat flux paths along the imperfect interfaces. HGB-CBM with larger volume fraction of HGB and smaller thermal conductivity of bead wall can provide better thermal insulation effect, which could provide reference for using HGB-CBM as thermal-insulating material in building engineering.

Thermoelectric Generator Through Dual-Direction Thermal Regulation by Thermal Diodes for Waste Heat Harvesting.

Thermal energy harvesting provides an opportunity for multi-node systems to achieve self-power autonomy. Thermoelectric generators (TEGs), either by thermocouple arrangement with higher-aspect-ratios or thermoelectric films overlay, are limited by the small temperature difference and its short-duration (less than dozens of minutes), hindering the harvesting efficiency. Here, by introducing thermal diodes with dual-direction thermal regulation ability to optimize the heat flux path, the proposed TEGs exhibit enhanced power-supply capability with unprecedented long-duration (more than hours). In contrast with conventional TEGs with fixed-leg dimensions enabled single output, these compact-TEGs can supply up to fourteen output-channels for selection, the produced power ranges from 1.11 to 921.99µW, open circuit voltage ranges from 8.07 to 51.32mV, when the natural temperature difference is 53.84°C. Compared to the most recent TEGs, the proposed TEGs in this study indicate higher power (more than hundreds times) and much longer output duration (2.4-120 times) in a compact manner.

Importance of surface roughness on the magnetic properties of additively manufactured FeSi thin walls

Thin-walled structures are being used in soft magnetic components manufactured by additive manufacturing to limit eddy current losses in AC machines. Fe-6.5wt %Si has been shown to be a promising material in such components, however most characterisation has taken place using thicker bulk material. Thermal conditions and microstructure have been shown to differ within thin-walled structures, hence magnetic properties may also differ. This study characterises the magnetic properties of thin-walled structures, showing that the 〈001〉 texture usually apparent in laser powder-bed fusion does not persist in thin-walled samples built at an angle to the build platform. Surface roughness (Sa) is shown to increase with build angle from 28 µm when perpendicular to the build platform, to 80 µm when parallel, causing a deterioration in magnetic properties such as susceptibility which is reduced by up to 25 %. Improvements in magnetic properties are demonstrated for samples with lower surface roughness due to improved laser parameters, with even larger improvements available when using polishing as a post-process finishing operation which was shown to improve susceptibility by over 10 %. This study enables the designers of soft magnetic components made by additive manufacturing, the freedom to design magnetic flux paths at any angle in the build chamber and gives surface roughness as a key parameter to improve magnetic properties.

Influence of magnetic field on MHD mixed convection in lid-driven cavity with heated wavy bottom surface

This study investigates the influence of a rectangular heat source on magnetohydrodynamic hybrid convection flow in a lid-driven cavity. The effects of various parameters, such as the heat source size, magnetic field strength, and heat absorption/generation, are analyzed. The results show that increasing the heat source size decreases the average Nusselt number along the heated wall. The average Nusselt number also decreases with higher magnetic field strength and heat generation, while it increases with heat absorption. The major finding is to apply an important technique the Galerkin weighted residual technique of the finite element (FE) method to solve the non-dimensional equations and the associated boundary conditions. The isotherms are used to show the temperature distribution in a domain. Streamline present the flow field in the enclosure. However, it is easy to realize the direction and intensity of the heat transfer particularly in convection problems which the path of heat flux is perpendicular and the isotherm due to convection effect. Thus, the purpose of this research is to study the results of mixed convection. The effects of location and height of the partitions are considered for the various Richardson numbers. Fluid flow field, thermal field and heat transfer are presented through the streamlines and isotherms, respectively. Results are substantiated relating to the published work.