Distribution Of Magnetic Induction Intensity Research Articles

Dual-range TMR current sensor based on magnetic shunt/aggregation effects utilizing single magnetic ring structure

In this paper, we propose and design a novel dual-range tunnel magnetoresistance (TMR) current sensor with a single magnetic ring structure. This design incorporates two distinct magnetic guiding effects, namely magnetic shunt and magnetic aggregation, within the same magnetic ring. By integrating a high-sensitivity TMR sensor chip with a closed-loop feedback circuit, we achieve a TMR current sensor with excellent linearity, high resolution, as well as high frequency response. The magnetic ring structure is first modeled and simulated, establishing a correlation between the distribution of magnetic induction intensity and the parameters of the magnetic ring and feedback coils. Through simulation optimization and theoretical calculations, we determine the optimal positions for TMR sensor chips in the magnetic ring, suitable for both current ranges. When a signal current is present, the TMR sensor chip generates a weak differential voltage signal, which is subsequently amplified, processed, and automatically transmitted to the laptop via a serial port. Furthermore, the sensor allows for automatic switching between the two current ranges. The results demonstrate that our designed dual-range current sensor exhibits outstanding performance characteristics, including a high resolution of 500 μA in the small range, accuracy of 0.10%, excellent linearity of 0.011%, and a fast frequency response of 500 kHz. These features make it highly applicable in various fields such as new energy vehicles and smart grids, indicating promising prospects for its widespread utilization.

Numerical simulation of the electromagnetic field in the secondary cooling zone of arc-shaped slabs

The magnetic field characteristics due to electromagnetic stirring in the secondary cooling zone of an extra-thick slab during continuous casting are numerically determined using Maxwell's equations, with particular emphasis on the distribution of magnetic induction intensity and electromagnetic force, as well as the influence of process parameters on the magnetic field. The orientation of the electromagnetic force is the same when the electromagnetic stirrers at the 30° and 60° posistions of the arc-shaped slab are powered in the same direction; otherwise, the orientation is opposite. The magnetic induction at the centre of the section of the stirrer's central axis at the 30° positio, as well as the current, frequency, and fitting formulae, are as follows: B = {0.075I(1/A)-0.3} mT and B = {-1.75f(1/Hz)+22} mT. The electromagnetic force and current fitting formula at the central point of the B-B section is F = {0.03168I2(1/A2)-03.762I(1/A)+326.7} N/m3, and the fitting formula of electromagnetic force and frequency at the centre point is divided into two segments. The first takes the form of a parabola: = {-21((f-4.3)-(1/Hz)2)+970} N/m3, and the second segment is negative linear: F = {-1.65f(1/Hz)+51.5} N/m3.

A smart structural optimization method of magnetorheological damper for ultra-precision machine tool

To address the problem of multi-source vibration in ultra-precision machine tools, a vibration reduction stand was designed by replacing passive damping components with magnetorheological dampers (MRDs). In this work, the structural parameters of MRDs were optimized using an improved pelican optimization algorithm (IPOA) to realize the maximum capability in reducing vibration. Firstly, the working principle of MRDs was explained, and the mathematical models of MRDs were established. Then, an IPOA based on singer chaotic mapping, nonlinear inertia weight factor, and Cauchy mutation strategy was proposed to enhance the global search capability and convergence efficiency of the algorithm. Subsequently, the IPOA was applied to optimize key structural parameters of MRDs, including output damping force, controllable damping range, response time, and power consumption. Finally, COMSOL Multiphysics software was used to verify the effectiveness of the proposed algorithm by comparing the magnetic induction intensity distribution of MRDs before and after optimization, as well as the variation of the four performance indexes under the different applied currents. After being optimized using the proposed IPOA, the MRDs can deliver a larger maximum damping force and a wider damping controllable range, with less power consumption and quick response, which could meet the requirement for vibration suppression of ultra-precision machine tools.

Quasi-Static Modelling of a Full-Channel Effective Magnetorheological Damper with Trapezoidal Magnetic Rings.

Magnetorheological damper (MRD) has been successfully applied to vehicle suspension systems as an intelligent core component. Most conventional MRDs have closed rectangle-shaped magnetic circuits, resulting in a short effective working length and negligible damping force. To address the above issues, a novel full-channel effective MRD with trapezoidal magnetic rings (FEMRD_TMR) is proposed. The trapezoidal magnetic ring can shunt the magnetic circuit, distributing it evenly along the damping channel and increasing the effective working length. Additionally, which has the same variation trend as the magnetic flux through it, makes the magnetic induction intensity distribution more uniform to reduce the magnetic saturation problem. Theoretically analyzing the damping characteristics of the FEMRD_TMR, a quasi-static model is developed to forecast the output damping force. The structural design of MRD is challenging since conventional quasi-static models rely on the yield stress of magnetorheological fluid (MRF) to reflect the rheological property, which cannot be directly observed and is challenging to calculate. The Takagi-Sugeno (T-S) fuzzy neural network and a unique magnetic circuit computation are offered as a novel quasi-static modeling approach to address the issue. The MRF's yield stress is linearized into magnetic induction intensity functions by the T-S fuzzy neural network and then converted into the MRD's structural size by the special magnetic circuit calculation. Therefore, the proposed quasi-static model can directly reflect the relationship between the damping force and structure size, simplifying MRD's structure design. The novel quasi-static model is shown to be more straightforward and understandable than the conventional Bingham quasi-static model and to have approximately accurate damping force prediction when compared to experimental data.

A magnetic field constrained type of multi-barrel common-rail railgun

Adopting the simultaneous launch mode of small and medium caliber railgun is an important means to increase the firepower density, improve the hit probability and strike efficiency. Based on this requirement, this paper creatively proposed a new multi-barrel simultaneous launch EM railgun, named magnetic field constrained type of multi-barrel common-rail railgun. The basic idea is to integrate multiple single-turn rail launchers with a specific structure into one launcher, and “merge” one rail of each single-turn rail launcher with a tight structure combination and arrange it in the center to form the “common rail” of multi-barrel launcher. The other rail of each rail launcher is evenly distributed around the “common rail” in the form of petals, forming the “outer rail” of each rail launcher. “Common rail” and all “outer rails” together form a multi-barrel rail launcher. With the increase of the number of barrels, the current of each barrel is superimposed many times in the common-rail, which greatly improves the magnetic induction intensity of the inner bore, thus improving the launching efficiency of the system. In order to overcome the problem of high magnetic induction intensity near the common-rail and low magnetic induction intensity near the external rail caused, a magnetic field constrained structure is added to the external rail to form a magnetic field constrained type of multi-barrel common-rail railgun. The basic structure of electromagnetic railgun with different number of barrels is simulated, and the spatial distribution characteristics of magnetic field are analyzed. Based on the magnetic field analysis, the interior ballistic simulation of the multi-barrel common-rail railgun is carried out, and the interior ballistic characteristics and launching efficiency of various numbers of barrels are analyzed. The simulation results show that the magnetic field constrained type of multi-barrel common-rail railgun can effectively improve the magnetic induction intensity near the external rail, improve the uniformity of the magnetic induction intensity distribution in the inner bore, and improve the inductance gradient, thus increasing the system efficiency. The structure of the multi-barrel common-rail railgun provides a new idea for the engineering application of the multi-barrel simultaneous launch mode.

Enhancing Power Transmission Stability of AUV’s Wireless Power Transfer System with Compact Planar Magnetic Coupler

In this paper, a wireless power transfer (WPT) system with a compact planar magnetic coupler for an autonomous underwater vehicle (AUV) is proposed. A passive induction (PI) coil is integrated into the circular transmitter (Tx) coil to build a uniform magnetic field (UMF), which can guarantee the stable output of the WPT system under uncertain radial and axial misalignments for AUV. Based on normalized magnetic induction intensity distribution analysis, a UMF constructing method with a PI coil is given, aiming to eliminate the fluctuation of magnetic field intensity, and the PI coil design principles and flow chart are obtained. The theoretical analysis shows the proposed integrated coil can effectively enhance the radial misalignment tolerance compared with a conventional circular spiral coil. The zero-phase angle (ZPA) input condition can be achieved by adjusting the series capacitor connected with the Tx coil in S-S compensation topology. Experimental results show that the proposed magnetic coupler containing an integrated coil significantly improves the stability of output power and power transfer efficiency within the possible radial and axial misalignments compared with a conventional coupler. It was demonstrated that the output power changes less than 5.5% and the power transfer efficiency maintains at approximately 84.5% in arbitrary radial positions within the possible working region with an axial transfer distance of 50 mm in saltwater.

Influence of structural parameters on the pulse effect of pulsed coils

Large-area icing is a natural disaster that presents a serious threat to the safety of aerospace and power systems, so achieving fast and efficient de-icing is an important cornerstone of energy security. In this paper, a physical model of the field-circuit coupling of the pulsed coil is established. The transient process of the pulsed coil was solved by numerical calculation method, and the magnetic induction intensity distribution, pulse current, impulse force and pulse effect under different cases were obtained. The electromagnetic parameters and pulse effect of the pulsed coil under different structural parameters are compared, and the influence of structural parameters on the pulse effect is analyzed. The results show that the pulse effect can be improved by adopting a reasonable cross-sectional form, increasing the cross-sectional area, decreasing the inter-turn distance and increasing the number of turns and outer diameter. Finally, the electromagnetic parameters and pulse effect of the pulsed coil are verified by impact pendulum experiments, which prove the correctness of the model. The conclusions of this work can provide analytical paths and optimization ideas for the de-icing simulation and low-power design of electromagnetic impulse de-icing systems.

Effect of vertical electromagnetic stirring on solute distribution in billet continuous casting process

A volume averaged columnar solidification model, which couples the flow, temperature and solute concentration fields, is applied to simulate experimental continuous casting cases with and without vertical electromagnetic stirring (V-EMS). The calculated distribution of magnetic induction intensity and final macrosegregation maps are consistent with the experimental results. Calculation results reveal that the V-EMS promotes longitudinal melt flow, accelerates heat dissipation and solidification and finally reduces the central segregation of carbon. However, when V-EMS is applied, the solute distribution becomes asymmetric because the melt flow shows opposite directions between the near and far sides from stirrer. An obvious positive segregation band is observed at about 1/4 width of the billet near the stirrer in both calculated and experimental results. The position and degree of such positive segregation could be affected by installation height of stirrer, as demonstrated by additional simulation cases.

Selective Laser Sintering-Based 4D Printing of Magnetism-Responsive Grippers.

Components fabricated by four-dimensional (4D) printing hold the potential for applications in soft robotics because of their characteristics of responding to external stimuli. Grippers, being the common structures used in robotics, were fabricated by the selective laser sintering (SLS)-based 4D printing of magnetism-responsive materials and tested for remote-controllable deformation in an external magnetic field. A composite material consisting of magnetic Nd2Fe14B powder and thermoplastic polyurethane powder was selected as the raw material for the SLS; the magnetic particle acquired permanent magnetism by magnetization after the SLS process. Microscopic characterization showed the homogeneous dispersion of magnetic particles inside the polymer matrix. The magnetic induction intensity distribution was systematically investigated by both experiments and numerical simulations. The reliability of the numerical model proposed was justified by the excellent consistency between them. The deformation of the grippers could be regulated by tuning the magnetic particle content and the distance from the external magnet; the deformation mechanism is investigated numerically. The magnetic driving force and the corresponding horizontal displacement are calculated, thus having high accuracy compared with the existing research that obtained the deformation amount by only visual inspection. Mechanical properties of the SLS-fabricated magnetic polymer composite specimens were also studied because of their close relationship with the deformation behaviors. These findings provide guidance for future research on controllable deformation and driving force calculation for 4D printing.

Simulation Analysis of Static Characteristics of Electromagnetic Mechanism of Magnetic Holding Relay Based on ANSYS

As an important part of the magnetic latching relay, the design of its parameters will directly affect the static characteristics of the entire system. This article first explains the working principle of the magnetic latching relay and the electromagnetic field analysis theory. Based on this, a simplified model of the electromagnetic mechanism is established. The ANSYS finite element analysis software is used to simulate and analyze the electromagnetic mechanism. The electromagnetic generated by the electromagnetic mechanism under different parameters is obtained. The magnitude of the force and its magnetic induction intensity distribution cloud map provide a useful reference for the performance optimization of the magnetic holding relay and subsequent related research.

Simulation of the Magnetic Field Distribution and Voltage Error Characteristics of the Three-Phase Three-Component Combined Transformer With New Three-Cylinder Core Structure

The disadvantages of the traditional three-column core structure three-phase three-component (TPTC) transformer are its incomplete symmetry, the different magnetic circuit length, and the coupling parameters, which lead to each phase voltage error varying differently. In this article, a new structure optimization design of a new type of three-phase three-element combined transformer with a new three-cylinder core structure was proposed. The simulation analysis of the magnetic field distribution and the voltage error characteristics of the voltage transformer with the new three-cylinder core structure was carried out. Compared with the traditional three-column core structure TPTC transformer, the magnetic induction intensity distribution of the voltage transformer with the new three-cylinder core structure is more uniform. The simulation results of the voltage error characteristics under normal load condition also show that with the increase in voltage, the voltage error of the voltage transformer with the three-cylinder core structure changes gently, and the error difference between the three phases is smaller. The TPTC combined transformer with the new three-cylinder core structure has better error characteristics under normal load conditions.

Simulation and optimisation design of the solenoid valve

This study first analyses the problems that the solenoid valve generates during operation. Then the electromagnetic valve was modelled and ANSYS finite element analysis simulation software was used to simulate the electromagnetic field and transient magnetic field of the solenoid valve. The magnetic induction intensity distribution diagram and magnetic field distribution diagram of the electromagnet were obtained. According to the simulation results of the solenoid valve, the magnetic flux leakage line is blocked after the magnetic isolation cover is added, the magnetic induction strength of the iron core and the valve head is increased, the leakage magnetic flux is reduced, and the structure is optimised.

Numerical and experimental studies on a novel magneto-rheological fluid brake based on fluid-solid coupling.

The previous work of the authors indicated that the fluid-solid coupling effect of the magneto-rheological fluid and the brake disc is a necessary focus during braking process. In this study, a novel design of magneto-rheological fluid brake was proposed and studied theoretically and numerically, aiming to solve the prominent problem of heat dissipation, especially in the case of single emergency braking. First, based on the modified Bingham model, a parameter defined as the apparent equivalent viscosity was utilized to represent the relationship of magnetic field, flow field, and temperature field. The braking torque and the formula for calculating the impact factor of fluid-solid coupling employed for characterizing the associations among the thermal field and the stress field were established based on fluid-solid coupling. With a detailed explanation of simulation method, the distribution disciplinarian's numerical simulation of each field was analyzed using COMSOL software. To validate the accuracy of the established model on the designed magneto-rheological fluid brake, the prototype was also manufactured, and results achieved experimentally which were measured on inertia test system of brake, for braking torque, motion parameters, and surface temperature in braking process, were compared with simulations. Simulation results manifested that the designed magneto-rheological fluid brake's magnetic circuit structure is feasible based on magnetic induction intensity distribution. Finally, it has been shown that the simulations appear to be basically consistent with the experimental results, and the heat dissipation of the designed magneto-rheological fluid brake is partially improved. These results might contribute to the structure design, optimization, and improvement of magneto-rheological fluid products, extending the previous work on fluid-solid coupling analyses.

Conceptual Design of Scanning Magnets for Superconducting Proton Therapy Facility

The performance of scanning magnets is the key to the treatment of proton accelerator in nozzle of the Superconducting Proton Therapy System (SPTS), which directly affects the quality of the proton beam and the size of the radiation field. The scanning magnets set at the entrance of the beam irradiation system are two dipole magnets to scan the beam in both horizontal and vertical directions and form the irradiation field to be tumor shape. In this paper, the theoretical calculation and software simulation have carried out to design scanning magnets for the SPTS in brief. The distribution of magnetic field is improved by structure optimization of scanning magnet and comparative analysis of magnetic induction intensity distribution curve in medium plane. The optimum structures of scanning magnets are got, which can meet the beam integral field uniformity and improve scanning accuracy. The study provides the key technical support to proton therapy of the SPTS.

Energy Storage Characteristics of MJ-Class Toroidal HTS-SMES Considering Maximum Value of Perpendicular Magnetic Field

The Superconducting Magnet Energy Storage (SMES) will be more and more popular in the electric power system in the near future. A toroidal SMES magnet with large capacity is a tendency for SMES because it has great energy density and low stray field. Firstly, a toroidal HTS-SMES magnet model is built to obtain the maximum value of the perpendicular magnetic field by the finite element method (FEM), and then the storage energy is calculated. Secondly, the operating current Iop=1kA and internal radius Ri=150mm keep unchangeable to research the relationship for the storage energy E, the number of double pancake coil (DPC) n wound by 150m YBCO tapes and the distance from the element coil center to the toroidal magnet center R. Finally, a 3 MJ toroidal HTS-SMES magnet is designed using the characteristic analysis results and its distribution of magnetic induction intensity and stray field are discussed in detail.

Viscosity monitoring and control on oil-film bearing lubrication with ferrofluids

Ferrofluid application in the oil-film bearing can improve the viscosity and the load-carrying capacity in a magnetic field. A solenoid was developed to provide magnetic field for ferrofluid, using which the distribution of magnetic induction intensity was calculated. The viscosity equation of ferrofluid was derived. The effects of oil-film temperature T, oil-film pressure P and magnetic intensity H on ferrofluid viscosity ηf was analyzed and tested by an unifactor experiment method. The control equations and transfer functions of each variable were given based on a large-scale oil-film bearing test rig. The variations of P, T, H and ηf were simulated and monitored by a reasonable control strategy. The results suggest that the viscosity increment by magnetic intensity could compensate the viscosity decrement by temperature rise.

The Magnetic Field Analysis of Dual-Coil Self-Sensing Actuator

This paper introduced working principle of dual-coil self-sensing actuator based on magnetically controlled shape memory alloy (MSMA). The ANSYS software was used to establish the finite element model of MSMA dual-coil self-sensing actuator. Edge element method was adopted to analyze the MSMA dual-coil self-sensing actuator's 3-D static magnetic field under the influence of different excitation voltages. The analysis obtained MSMA and silicon steel sheet distribution of magnetic induction intensity and the magnetic field intensity, has further confirmed the reliability of MSMA dual-coil self-sensing actuator, and has given the MSMA length relations along with the magnetic induction intensity changes. The results show that magnetic field analysis has certain reference value to the MSMA practical application.