Position Of Permanent Magnet Research Articles

State-restricted adaptive control of a multilevel rotating electromagnetic mechanical flexible device using electromagnetic actuators

This work presents the development of a multilevel electromagnetic actuation system that controls the shape of a flexible rotatory robotic structure. An array of electromagnets is used as the set of actuators that regulate the position of permanent magnets within the flexible device. The primary outcome of this study is the design and experimental validation of the multilevel rotating device. In addition, the theoretical description of the system motion under electromagnetic actuation is formulated using Euler–Lagrange and electromagnetic theories. Given the developed model, a theoretical study leads to designing an adaptive control that considers motion restrictions in the flexible device. The controller aims to modify the current applied to the electromagnets, which changes the interaction forces between the electromagnet and the permanent magnets in the robotic flexible structure. A set of numerical simulations confirms the proposed controller’s effectiveness compared to the traditional state feedback approach that does not consider the state restrictions, which is implemented in devices that also operate under an electromagnetic approach. Furthermore, an experimental version of the flexible device allows for testing of the developed controller. The experimental results show the suitability of the proposed control to generate non-oscillatory controlled motion during the regulation of the flexible mechanic device shape.

Effects of Differential Magnetic Field/Tensor and Redundant Measurements on Multi-DOF Motion Estimation of a Magnetic Sensing System

This paper presents a multi-DOF motion sensing system consisting of a permanent magnet (PM) and a magnetic tensor sensor (MTS) comprising a 3×3 array of three-axis digital magnetic flux density (MFD) sensors, and the methods to measure their relative MTS-PM position/ orientation in a 3D space. The design enables redundant differential measurements of MFD vectors and gradient tensor components to account for the singularities due to matrix inversion, providing a basis to explore different methods for multi-DOF estimation of the PM position/ pose. Formulated as a two-stage linear least-square (LS) problem to take advantage of the dipole simplicity and exploit its physics revealed by its inverse model to guide the design of a fully connected artificial neural network (ANN) to account for the MTS measurement noise and un-modeled factors, a prototype multi-MTS system capable of 5-DOF motion measurements is developed and evaluated experimentally along with a study analyzing the parametric effects on the estimation accuracy; both stationary and moving sensor scenarios are considered. Enhanced with a fully connected ANN, an accuracy within a root-mean-square error (RMSE) of 40μm spatial position and 0.1° pose can be uniquely obtained without subtracting a predetermined geomagnetic field in both fixed and moving multi-MTS scenarios, representing a significant improvement over the (0.5mm, 1°) RMSE of the single-MTS.

Torque Ripple Suppression Research of V-Shaped External Rotor Permanent Magnet Motor

Aiming at the problems of large torque ripple and poor output torque performance of external rotor permanent magnet synchronous motors, this paper took a three-phase 24-slot 19-pole external rotor motor as the research object, uses the magnetic circuit method and Lorentz theorem to analyze and calculate the motor torque, and improved the output torque by optimizing the position parameters of the V-shaped permanent magnet. The output torque was further optimized by a circular groove on the side of the stator teeth. The finite element simulation results show that the output performance of the motor can be improved by selecting the proper permanent magnet position. Stator tooth chooses slot position for Z = 1.2 mm, R = 3.5 mm torque ripple when dropped by 81.9%, up 7.6% on the output torque, motor performance is improved.

IONIC WIND FLOW CHARACTERISTICS OF A MAGNETIC-FIELD-ENHANCED SOLID-STATE FAN AND ITS PERFORMANCE IN LIGHT-EMITTING DIODE COOLING APPLICATIONS

Solid-state fans (SSFs) have distinct advantages over traditional cooling fans in the thermal management of high-power electronics. In this work, a magnetic-field-enhanced SSF is proposed, and the physical model of negative corona discharge superimposed by an electromagnetic field is established. A computational model is used to calculate and analyze the effect of the magnetic field on the ionic wind distribution. The magnetic flux density and permanent magnet position distribution in the SSF are optimized experimentally, and the optimized SSF is applied to LED chip cooling. The findings show that adding a magnetic field encourages electrons to collide with neutral gas molecules and enhances the driving force of charged particles. The ionic wind velocity and mean driving force at the SSF's outlet will grow as magnetic flux density rises, and the ionic wind flow distribution will show apparent divergence. When the permanent magnet spacing is 15 mm, the highest ionic wind velocity is 2.82 m/s, and the mean driving force of SSF increases by 30.2%. The magnetic-field-enhanced SSF has a better LED-chip cooling effect, the maximum junction temperature drop is 11.6°C, and the cooling efficiency is higher. This research introduces a novel way of improving the cooling of electronics.

Reduction of cogging torque of radial flux permanent magnet brushless DC motor by magnet shifting technique

Introduction. In spite of many advantages of radial flux permanent magnet brushless DC motors it suffers from the distinct disadvantage of high cogging torque. The designer must emphasize to reduce the cogging torque during the design stage. This paper introduces magnet shifting technique to mitigate cogging torque of surface mounted radial flux brushless DC motor. Methodology. Initially 200 W, 1000 rpm surface mounted radial flux permanent magnet brushless DC motor is designed with symmetrical placement of permanent magnets with respect to each other on rotor core. Cogging torque profile of this initial motor is obtained by performing finite element modelling and analysis. Originality. This design has been improved by shifting the position of permanent magnets with respect to adjacent permanent magnets. The effect of magnet shifting on cogging torque has been analyzed by performing finite element analysis. Results. It has been examined that the peak to peak cogging torque is decreased from 1.1 N×m to 0.6 N×m with shifting of permanent magnets respectively.

Electromagnetic Engine Controlled using IR Sensor

The base idea of this paper is to control the electromagnetic engine to enhance a smooth rotation by measuring distance of the piston using an IR sensor. This electromagnetic engine consists of an electromagnet, permanent magnet, Infrared Sensor, powerful microcontroller and power supply. The permanent magnet acts as a piston in this electromagnetic engine, it has magnetic field energy for a proper function. The position of permanent magnet has to be noted for electromagnets energisation in order to reduce power consumption by electromagnet. The infrared sensor mounted with electromagnet set and pointed towards permanent magnet, whenever the permanent magnet moves towards electromagnet, sensor reads the change in magnetic piston position. The electromagnet is energized on the reach of permanent magnet near electromagnet. Control of electromagnets power supply is depends on the signal provided by IR sensor, this sensor is mainly makes timing control of power drive circuit through the microcontroller. This makes engine to run continuously and reducing its power consumption by providing a pulse to electromagnet.

Sensitivity-Based Optimization of Interior Permanent Magnet Synchronous Motor for Torque Characteristic Enhancement

This paper presents a multi-objective optimal rotor design for an interior permanent magnet synchronous motor (IPMSM) based on finite element analysis. Due to the importance of torque characteristic in electromagnetic design of IPMSMs, the main efforts of this study are focused on finding a proper trade-off for its torque profile challenges. In this regard, in order to attain high average torque and low torque ripple, the influence of several key factors, such as the permanent magnet (PM) arrangements, PM positions and PM sizes, are examined. Subsequently, according to the outcomes of the performed sensitivity analysis, the appropriate variation interval of the parameters as well as their initial values is determined. Employing such a deterministic optimization algorithm, which does not need large sample points, minimizes the finite element computational cost and leads to accelerate the convergence process. The two-dimensional finite element model (FEM) of an IPMSM is used to perform a sensitivity analysis and establish a multi-objective FEM-based optimization.

Comparative Study of Dual PM Vernier Machines

In this paper, two types of dual permanent magnet (PM) machines, i.e., stator slot dual-PM (SSDPM) machine and split-tooth dual-PM (STDPM) machine, are investigated and compared. Both machines have consequent pole structure with Halbach array PMs. Their difference lies in the position of stator PM. The SSDPM machine has Halbach array PMs in the stator slots, while the STDPM machine has PMs between the split teeth. Torque characteristics, i.e., average torques and torque ripples, of different slot/pole number combinations of the two machines are compared. The 24 stator slots/20 rotor slots/4 armature pole pair (24S20R4Pa) SSDPM machine with distributed windings and the 24 stator slots/10 rotor slots/4 armature pole pair (12S20R4Pa) STDPM machine with concentrated windings are compared under both open-circuit and on-load conditions. The results show that the SSDPM machine is more competitive by delivering higher torque density and higher power density.

Performance Evaluation of Posture Measurement System for a Rotor of a Spherical Motor

An electromagnetic-type spherical motor rotates by the electromagnetic force worked between a rotor with permanent magnets and a stator with electromagnets. The torque map control method proposed by Kasashima, et. al., can control a spherical motor to rotate in any direction by adjusting the currents to excite electromagnets. The measurement of relative rotor posture to stator is necessary for the torque map control method because the currents to excite electromagnets to rotate the rotor around a specified rotation axis depend on relative rotor posture. A posture measurement technique of the rotor using Hall sensors is studied. A prototype posture measurement device developed is arranged Hall sensors in a mesh format to cover some part of the rotor in order to measure magnetic field generated by permanent magnets. It is necessary to estimate the position of permanent magnets of the rotor for the measurement of rotor posture. However, the permanent magnet position may not be estimated if there is an error in the distance measurement between Hall sensors and permanent magnets calculated from the output values of the Hall sensors.

Robotic Localization Based on Planar Cable Robot and Hall Sensor Array Applied to Magnetic Capsule Endoscope.

Recently an active locomotive capsule endoscope (CE) for diagnosis and treatment in the digestive system has been widely studied. However, real-time localization to achieve precise feedback control and record suspicious positioning in the intestine is still challenging owing to the limitation of capsule size, relatively large diagnostic volume, and compatibility of other devices in clinical site. To address this issue, we present a novel robotic localization sensing methodology based on the kinematics of a planar cable driven parallel robot (CDPR) and measurements of the quasistatic magnetic field of a Hall effect sensor (HES) array. The arrangement of HES and the Levenberg-Marquardt (LM) algorithm are applied to estimate the position of the permanent magnet (PM) in the CE, and the planar CDPR is incorporated to follow the PM in the CE. By tracking control of the planar CDPR, the position of PM in any arbitrary position can be obtained through robot forward kinematics with respect to the global coordinates at the bedside. The experimental results show that the root mean square error (RMSE) for the estimated position value of PM was less than 1.13 mm in the X, Y, and Z directions and less than 1.14° in the and orientation, where the sensing space could be extended to ±70 mm for the given 34 × 34 mm2 HES array and the average moving distance in the Z-direction is 40 ± 2.42 mm. The proposed method of the robotic sensing with HES and CDPR may advance the sensing space expansion technology by utilizing the provided single sensor module of limited sensible volume.

Study of permanent magnet configuration in alternate circumferential and radial flux permanent magnet flux switching machines (AlCiRaF-PMFSM)

Alternate circumferential and radial flux (AlCiRaF) is new design in PMSFM. AlCiRaF PMFSM offers high torque and power density. However, AlCiRaF PMFSM is a novel design that a good opportunity to be potential improved further. In this research, the nine design of permanent magnet configuration in AlCiRaF PMFSM is proposed to compare each performance possibilities. The configurations of permanent magnet are introduced to study the performance effect by changing the permanent magnet position which is PM-Bottom, PM-Middle and PM-Top for both circumferential and radial direction. Besides, the permanent magnet structure design will improve field winding area structure to provide space for future improvement. Weight of all the permanent magnets are estimated to be 0.5 kg altogether. Initially, design procedures of the all motor including parts drawing, material and condition setting, the properties setting are all explained. Then, coil arrangement test is conducted to perform 3 phase armature coil arrangement. Then, no load analysis is conducted to analyze cogging torque, flux linkage, flux distribution and back-EMF of motor followed by load analysis which analyze the torque speed characteristics and output power of the motor with different permanent magnet configuration. No load analysis and load analysis are conducted using finite element analysis of JMAG Designer 16.0. Finally, it is found that there is no significant difference that resulted and the best permanent magnet configuration compared to the Existing AlCiRaF PMFSM permanent magnet design is TRBC PM and MRBC PM due to the capability to produce high output torque and power based on the analysis conducted.

Three-dimensional numerical analysis of focusing and separation of diamagnetic particles in ferrofluid

Focusing and separation of particles and cells by magnetophoresis are important steps in many applications. In simple terms, the magnetophoresis can be classified into a positive one and a negative one. The most important characteristic of negative magnetophoresis is that particles and cells can be manipulated in a label-free manner. In this paper, continuous separation based on negative magnetophoresis is studied numerically using a three-dimensional model considering the interaction between particles and the ferrofluid. Firstly, the separation of two sized particles is investigated with a straight microchannel with two opposite permanent magnets for focusing particles before their separation by another bias magnet. Then the influence of size and position of permanent magnets and geometry of microchannel are investigated to achieve a better particle separation. Moreover, the effects of the concentration of the ferrofluid, the size difference of the particles, the magnet-channel distance and the flow velocity on the particle separation are analyzed.

The effect of permanent magnet position on axial and radial load capability in axial hybrid magnetic bearing

The axial and radial load capacity of axial hybrid magnetic bearing (HMB) is critical for the magnetic levitation system. In this paper, the effect of permanent magnet (PM) position on axial and radial magnetic force and stiffness in axial HMB is investigated. Six different configurations are considered and the equivalent magnetic circuits of HMBs for each configuration is built and studied based on the distribution of magnetic field and magnetic leakage. The dependence of axial and radial magnetic force and stiffness on the axial displacement, radial displacement and control current is calculated and investigated for different configurations. To validate the calculated results, the axial and radial magnetic forces for each configuration are simulated by finite element method. A good agreement between the calculated and simulated results validated the proposed magnetic circuit models.

Performance Analysis of an Axial Magnetic-Field-Modulated Brushless Double-Rotor Machine for Hybrid Electric Vehicles

The series–parallel hybrid electric vehicles (HEVs) are widely developed due to the advantages of high fuel economy and good driving performance. The electronic continuously variable transmission, which is a key part of the HEV, can be based on planetary gear or compound structure machine (CSM). The axial magnetic-field-modulated brushless double-rotor machine (AMFM-BDRM), which can be connected with a traditional permanent-magnet synchronous machine to form a CSM, is investigated in this paper. The axial tilting torque is analyzed, and the necessary condition for avoiding it is given. Compared with the single-sided topology, the double-sided AMFM-BDRM is recommended to eliminate the axial tilting torque. The influences of winding turns, diameter ratio, ferromagnetic block and permanent-magnet (PM) dimensions, air-gap length, phase current, and internal power-factor angle on the power factor and electromagnetic torque are analyzed, and it is found that the increase of power factor is sometimes at the expense of sacrificing the electromagnetic torque. The effects of speed and PM segmentation on losses are investigated, and the circumferentially double-segmented PM is selected. The influences of dissymmetry on air-gap flux density, no-load back electromotive force, electromagnetic torque, and axial magnetic force are analyzed, and it is found that the offset, tilt, and PM position deviation of the PM rotor have different degree effects on machine performances. Experiments are carried out, and the correctness of the analysis and simulation results are verified.

The influence of cyclical lateral displacements on levitation and guidance force for the system of coated conductor stacks and permanent magnets

For the development of levitation bearings and transportation systems based on coated conductor (CC) tapes it is important to know not only information on levitation force at vertical displacement, but also the data on stability of the system during lateral displacements of superconductor relative to permanent magnets. In this paper, we present new experimental results on investigation of both levitation and guidance forces of CC-tapes stacks subjected to cyclical lateral displacements relative to the position of permanent magnet. For the measurements we used 12 mm wide commercially available CC-tape manufactured by SuperOx. The long tape was cut into pieces 12 mm × 12 mm which then put to the stack. Total number of the single tape in the stack N was varied from 5 to 100. Under lateral displacement we measured the dependencies of levitation and guidance forces on value of displacement for various number of N and found that both levitation and guidance forces tend to decrease as a number of periodical cycles of displacements increase. The rate of reducing of forces was observed to depend on the number of tapes in the stack. We observed that dependencies of levitation and lateral forces on lateral displacements have a hysteresis. The area of hysteresis, which corresponds to the magnitude of energy losses, was found to decrease with increasing of number of elements in the stack. Experimental results are in a good agreement with the theoretical calculations of lateral force.

Optimal Design of PMa-synRM for an Electric Propulsion System Considering Wide Operation Range and Demagnetization

In this paper, optimal design of permanent magnet assisted synchronous reluctance motor (PMa-synRM) for propulsion system is conducted. The main purpose of the design is widening operation region, maintaining advantages of a synchronous reluctance motor with improved noise, vibration, and harshness and demagnetization characteristics appropriate for a propulsion system. First of all, permanent magnet position and combination is optimized considering design purpose. Then, diagnosis of demagnetization has been performed to eliminate the models that are partially demagnetized due to the flux from the armature winding. Finally, a detailed design has been conducted for optimization on the dimensions of the permanent magnet and air-layer. Characteristic analysis of the designed model is conducted and comparison has been made to a reluctance synchronous motor to verify the effectiveness of the design. Calculations have been delivered by numerical analysis based on a finite element method.

Study on Adaptive-Passive and Semi-Active Eddy Current Tuned Mass Damper with Variable Damping

Tuned mass damper (TMD) is a widely used vibration control device, consisting of a mass, some springs and damping elements. Viscous damper is mostly used as a damping element; however, it has many unsustainable problems, e.g., poor durability, sensitive to the change of temperature, difficult to adjust the damping, oil leakage etc. In this paper, a new sustainable adaptive-passive eddy current tuned mass damper (ECTMD) with variable damping, which is very easy to be further upgraded to a semi-active one, is proposed. Four important parameters, e.g., adsorption position of permanent magnets, thickness of the conductive plate, thickness of the extra steel plate and the air gap between permanent magnets and the conductive plate are investigated by a parametric study. Two new evaluation indexes are put forward to indicate the damping mechanism of the proposed device. The relationship between effective damping coefficient and air gap is fitted through a quadratic function. Then, the corresponding design method of the proposed adaptive–passive ECTMD is presented. At last, the previous adaptive–passive ECTMD is upgraded to a semi-active one, which can adjust its eddy current damping through adjusting its air gap in real-time, based on the linear-quadratic-Gaussian algorithm. The effectiveness of semi-active ECTMD is evaluated through harmonic excitations and human-induced excitations. The results show that the semi-active ECTMD with variable damping has a better vibration control effect than the optimized passive one.

A Study on the Optimal Placement of Permanent Magnet in Hybrid Magnetic Levitation System for Thin Steel Plate by Electromagnet Installed in the Levitation and Horizontal Direction and Permanent Magnet

Thin steel plates are generally conveyed while in contact with rollers in the conveyance process. This leads to deterioration in the quality of the plate surface, such as flaws and peeling of the plated layer. The researchers in our laboratory have been involved in examining noncontact magnetic levitation control of the conveyance of a rectangular thin steel plate. We proposed hybrid electromagnetic levitation system which consists of electromagnets for levitation and horizontal positioning control and permanent magnets. In this study, the gap, number and optimal position of permanent magnets for suppressing the displacement of a magnetically levitated thin steel plate were investigated using thin steel plates by genetic algorithm. After that we examine effectiveness of optimal position of permanent magnets.

Thermomagnetic convection of oxygen in a square enclosure under non-uniform magnetic field

The effects of magnet position and magnet strength on the thermomagnetic convection of gaseous oxygen in a square enclosure under combined magnetic and gravity fields are numerically studied. The magnetic field is provided by a Neodymium-Iron-Boron permanent magnet which has a high magnetic energy product. The results show that the thermomagnetic convection is significantly affected by the relative location of the permanent magnet. Both the heat transfer and buoyancy driven flow near the lower part of the vertical hot wall are greatly enhanced when the magnet is placed near the hot wall. The largest local Nusselt number is enhanced by 152.7% for the studied largest magnet strength. The corresponding largest average Nusselt number also increases by 17.9%. The overall heat transfer increases with the increase of magnet strength when the magnet is placed near the hot wall, while the heat transfer increases first and then decreases with the increase of magnet strength when the magnet is placed near the cold wall. Optimal position of permanent magnet exists for best heat transfer enhancement.

Lateral Position Effect of Auxiliary Permanent Magnets on the Magnetic Force Properties of Cylindrical YBCO

The magnetic levitation force (MLF) and the guidance force (GF) should be improved for loading capacity and stability of Maglev systems, respectively. Although there are some ways to increase these properties, using of auxiliary onboard permanent magnets (PMs) can be considered as the most efficient one. The auxiliary PMs increase the MLF significantly but, at the same time, decrease the GF. We have searched a solution to overcome this problem in this study. Firstly, we have determined the optimum vertical positions of the auxiliary PMs and then we have investigated the vertical levitation force and lateral guidance force of hybrid Maglev system depending on lateral position of auxiliary PMs in different cooling heights (CHs). A cylindrical YBCO superconductor, fabricated by a top seeding method with the diameter of 45 mm and the height of 15 mm, was used as a high-temperature superconductor (HTS). The maximum increment rate in MLF and the minimum decrement rate in GF were observed as 277 and 54 %, respectively. The increment in MLF was obtained five times more than the decrement in GF, and this reality points out that the results of this study can be useful for improving the loading capacity and thus enhancing the practical applicability of Maglev systems.