Combination Of Permanent Magnet Research Articles

Improvement of titanium film uniformity by magnetron sputtering with electromagnetic coil design

A novel magnetron assembly based on a combination of permanent magnet and adjustable electromagnetic coil is proposed for improved uniformity of the magnetron sputtering deposition process. The design of the magnetron sputtering system containing a rotating substrate and an off-axis arranged magnetron. A numerical framework has been developed to describe the evolution of the plasma density and distribution of sputtered particles. Specifically, the finite element method (FEM) was used to calculate the magnetic field and to model the magnetron sputtering discharge, and binary-collision Monte Carlo method was used to determine the transport of sputtered atoms to the substrate. Through parametric analyses, it was found that increasing the substrate-to-target distance, gas pressure, and coil current intensity benefits the uniform distribution of particles. The condition where the off-axis displacement of the magnetron effectively enhances uniformity. A strategy for optimizing deposition uniformity by combining adjustable current with an off-axis magnetron arrangement was proposed, which reduce the non-uniformity of film thickness by 77.6 % compared to the traditional fixed magnetic field model.

Optimization design of a new hybrid magnetic circuit motor

The combination of permanent magnets and electrically excited windings creates an air gap magnetic field. The development of a hybrid magnetic circuit motor with an adjustable magnetic field is of great significance. This article introduces a hybrid magnetic circuit motor design that combines salient pole electromagnetic and permanent magnets. A tubular magnetic barrier has been designed to reduce inter-pole leakage and enhance the usage rate of permanent magnets in the hybrid magnetic circuit motor. The optimum eccentricity of the rotor has been accurately designed, resulting in an improved sinusoidal distribution of the air gap magnetic density waveform. An analysis of the static composite magnetic field under various excitation currents has been conducted, showcasing the capability of the hybrid magnetic circuit motor to stably adjust the air gap flux density level and output torque. A prototype has undergone comprehensive trial production and testing, conclusively confirming the machine’s superior output performance.

Parametric study of the axial force and negative stiffness of an electromagnetic mechanism for vibration isolation applications

Nonlinear vibration isolators that take advantage of negative stiffness elements can provide high static stiffness to bear high static loads and quasi-zero dynamic stiffness to widen the isolation frequency band and hence are desirable for vibration isolation. Electromagnetic negative stiffness elements can be used to design and fabricate quasi-zero-stiffness vibration isolators. Different combinations of permanent magnets and electromagnetic coils in attractive or repulsive configurations can lead to negative stiffness. The magnitude of the electromagnetic restoring force and negative stiffness is dependent upon many geometric and electromagnetic parameters and is controllable by adjusting the current in the electromagnetic coils. The present work compares the negative stiffness properties of three different configurations and provides a general guideline for selecting the appropriate configuration. The finite element method is used to simulate the magnetic fields and electromagnetic force acting on the permanent magnet. Numerical results are presented, and findings are validated by analytical solutions.

Design and analysis of coil spring suspension system using N4518 grade flux levitation for motor bikes

Riding comfort is of paramount importance when designing a suspension system considering vehicle dynamics & stability control. Generally, two-wheelers use springs, hydraulic and pneumatic-type damping mechanisms. The present work was a neoteric magnetic suspension system for two-wheelers that use both magnetic and spring cushioning effects to provide comfort to the rider. In this work, two Neodymium ferromagnetic materials were fixed inside the shock absorber cylinders facing same pole each other. The repulsive magnetic flux they produce when come closer due to shocking load was utilized as media for dampening the shock. The combination of permanent magnet with coiled spring has been utilized to enhance the cushioning effect against the shock transmitted due to acceleration on an uneven road condition. The designed suspension system was more efficient over other type of suspension systems, absorbs a greater number of shocks with high accuracy and had no leakage problem unlike in hydraulic and pneumatic system. The design was validated using 3D modelling and Ansys simulation. The beneficial software validation made the design tentative to work efficiently with less maintenance cost.

An Analysis of the Design of a Low Rotational Speed Permanent Magnet Generator That Uses Radial Flux

A radial flux permanent magnet generator can be effectively used in generating wind power at low speeds. This generator uses a combination of permanent magnets and a stator to produce electricity from the wind’s kinetic energy. The permanent magnets are arranged in a radial pattern, which reduces the amount of heat lost and therefore increases the generator’s efficiency. This design allows for a low rotational speed, which makes it suitable for applications such as wind turbines. The air gap between the rotor and the stator affects the output voltage and power due to the decrease in magnetic flux. This study aims to increase the generator’s output voltage and output power by fitting stator teeth widths to the stator teeth. The stator teeth width fitting design method adjusts the air gap between the stator and the rotor to a uniform size. This helps to reduce the pulsating torque and ensure that the output voltage and power are maximized. The three variables are the stator slot width, the rotor slot width, and the air gap width. By adjusting these variables, the stator teeth width fitting design method can adjust the air gap between the stator and rotor.

Modeling and Control of a Magnetic Levitation Platform

We present two models for a specific class of magnetic levitation system, a type of planar magnetic motor, designed for magnetic levitation of a single permanent magnet using a combination of permanent magnets and electromagnets. The first model is based on established semi-analytical solutions for magnetic fields generated by ideal solenoids, while the second model employs a novel discretization that is well suited for real-time control. Simulations show that the models have comparable accuracy to a standard filament model, but with a reduction in computational time of up to 98 %, for the discretized model. A simulation study demonstrates the models’ applicability for advanced control, using a linear-quadratic regulator (LQR) for stable levitation, and a nonlinear model predictive controller (NMPC) to showcase novel control behavior.

Simpler optimized stellarators using permanent magnets

A first-of-a-kind optimized stellarator for confining plasma has been designed and is being constructed with planar circular coils and permanent magnets composed of identical elements. The equilibrium is optimized to be quasi-axisymmetric for good particle confinement. The combination of permanent magnets and planar coils is significantly simpler to construct than fabricating three-dimensionally shaped coils, yet they are able to produce lower helical magnetic ripple than existing devices by two orders of magnitude in , a characteristic neoclassical transport metric.

Untethered Microrobot Motion Mechanism With Increased Longitudinal Force

Abstract The importance of an untethered microrobotic platform that can operate on high flowrate microfluidic channels for in vitro applications is increasing rapidly. This article presents a method to manipulate a microrobot in a fluidic chip when high flowrates (4 ml/min, 82.304 mm/s) are applied. This method is based on a novel permanent magnet-based diamagnetic levitation configuration. This configuration includes a thin layer of pyrolytic graphite, which is placed just below the microrobot. In this way, microrobot stability and manipulation capability are increased. Also, we aim to increase the longitudinal forces imposed on the microrobot to withstand the drag force proportional to the flowrate. Hence, magnetic field lines are generated more linearly around the microrobot by a different combination of permanent magnets. The proposed magnetic configuration, named “KERKAN configuration,” significantly improves the microrobot’s longitudinal forces. In this configuration, two different ring-shaped ferromagnetic magnets are used. One of the magnets has a smaller diameter than the other magnet. A combination of one smaller and one bigger magnet is placed above and below the microrobot. To validate the advantages of this configuration, analytical and simulation studies are conducted. Their results are then compared with experimental results. Experimental results are on par with analytical and simulation studies. KERKAN configuration has a lower displacement than the next best configuration at the highest flowrate we applied (relatively 3301 μm, %21.8).

Optimal Design of Novel Electromagnetic-Ring Active Balancing Actuator with Radial Excitation

Imbalance vibration is a typical failure mode of rotational machines and has significant negative effects on the efficiency, accuracy, and service life of equipment. To automatically reduce the imbalance vibration during the operational process, different types of active balancing actuators have been designed and widely applied in actual production. However, the existing electromagnetic-ring active balancing actuator is designed based on an axial excitation structure which can cause structural instability and has low electromagnetic driving efficiency. In this paper, a novel radial excitation structure and the working principle of an electromagnetic-ring active balancing actuator with a combined driving strategy are presented in detail. Then, based on a finite element model, the performance parameters of the actuator are analyzed, and reasonable design parameters are obtained. Self-locking torque measurements and comparative static and dynamic experiments are performed to validate the self-locking torque and driving efficiency of the actuator. The results indicate that this novel active balancing actuator has sufficient self-locking torque, achieves normal step rotation at 2000 r/min, and reduces the driving voltage by 12.5%. The proposed novel balancing actuator using radial excitation and a combination of permanent magnets and soft-iron blocks has improved electromagnetic efficiency and a more stable and compact structure.

Control and Operation of a Hybrid Actuator for Maglev Applications

Abstract The hybrid actuator presented in this article is meant to enable stationary and slow dynamic levitation in Maglev applications. The term ‘hybrid’ refers to the design of the actuator, which is a combination of permanent magnets (PM) and electromagnets. This paper presents an analytically computable control algorithm for the said hybrid actuator. The theory of magnetic circuits is summarized shortly and used to derive a cascaded control loop consisting of an inner current controller and an outer air gap controller. Since the uncontrolled hybrid actuator is inherently unstable, the system has to be stabilized. By introducing a PID-controller into the air gap control loop, the unstable behaviour of the uncontrolled system is changed into the system behaviour of a damped harmonic oscillator. The advantage of this approach is that the computed controller parameters of the PID-controller can easily be adjusted, so the system behaviour of damping and eigenfrequency can be selected within a certain range. For the execution of the control algorithm, a microcontroller (MCU) is used and for precise air gap measurement, an eddy current sensor is installed. Finally, the behaviour of the current- and air gap controller is discussed for different measurement results and the adjustable system behaviour of the damped harmonic oscillator is presented.

Dual aptamer assay for detection of Acinetobacter baumannii on an electromagnetically-driven microfluidic platform

Rapid detection of Acinetobacter baumannii (AB) is critical for limiting healthcare-associated infections and providing the best treatment for infected individuals. Herein an integrated microfluidic device for AB diagnosis utilizing a new dual aptamer assay was developed for point-of-care (POC) applications; magnetic beads coated with AB-specific aptamers were used to capture bacteria, and quantum dots (QD) bound to a second aptamer were utilized to quantify the amount of bacteria with a light-emitting diode (LED)-induced fluorescence module integrated into the device. Within a rapid detection of 30 min, a limit of detection of only 100 colony-forming units (CFU)/reaction was obtained, and all necessary microfluidic devices were actuated by a combination of permanent magnets and electromagnets. The pumping rate of the micropump was 270 μL/min at only 10 V, which is amenable for POC applications with lower power consumption, and only 10 μL of sample and reagents were required. Given these attributes, an automatic POC device was demonstrated which could perform a dual aptamer assay to diagnose AB by using electromagnetically-driven microfluidic system. This system provides a rapid, sensitive, low power and reagents consumption and fully automated for AB detection by using a dual aptamer assay. It will allow rapid clinical diagnosis of AB in the near future.

Characteristics of an ECR Sheet-Shaped Plasma Formed by a Combination of Permanent Magnets and Field Coils

Characteristics of an ECR Sheet-Shaped Plasma Formed by a Combination of Permanent Magnets and Field Coils

Effect of electromagnet-based fuel-reforming system on high-viscous and low-viscous biofuel fueled in heavy-duty CI engine

In the present study, a high-viscous biofuel, namely wheat germ oil (WGO), and a low-viscous biofuel, namely pine oil (PO), are used in a twin-cylinder diesel engine. The fuel ionization filter is fitted with a permanent magnet, an electromagnet, and the combination of permanent magnet and electromagnet, and their effect on the engine performance, emission, and combustion is studied. A fuel ionization filter placed in the fuel line, before the injection pump, ionizes the fuel molecules and increases the rate of disintegration of droplets due to a decrease in viscosity and surface tension. The tests are performed at a constant engine speed of 1500 rpm with loads varying from no load to full load at intervals of 25%. As compared to diesel, the engine operation with ionization filter increased brake thermal efficiency and reduced the fuel consumption for both PO and WGO. The increase in brake thermal efficiency is in the order: permanent magnet, electromagnet, and combination of electromagnet and permanent magnet. The magnetic field strength of electromagnet is higher than permanent magnet which tends to increase the ionization of the fuel. When both the magnets are combined, the magnetic field strength further increases resulting in more ionization of the fuel. It is also perceived that magnetic effect reduces the viscosity of the fuel. Regulated emissions, namely unburned hydrocarbons (HC), carbon monoxide (CO), and smoke emissions, reduced, whereas NOx emissions increased with WGO and ionization filter. With pine oil and ionization filter, all the regulated emissions decreased as compared to neat pine oil. The reduction in HC, CO, and smoke emissions was highest for combination of electromagnet and permanent magnet followed by electromagnet and permanent magnet. The study shows that combination of permanent magnet and electromagnet resulted in the best engine performance and emission characteristics.

Research of an Axial Flux Stator Partition Hybrid Excitation Brushless Synchronous Generator

A vehicular generator has stringent requirements on its weight and volume. As a combination of permanent magnet and electric excitation motor, hybrid excitation machine could meet the requirements of vehicular generator, with small size, light weight, adjustable output voltage. In this paper, an axial flux stator partition hybrid excitation brushless synchronous generator (ASHG) is proposed. First, the structure and operation principle of ASHM is illustrated. Afterwards, the shape of the magnetic pole is optimized to obtain the air-gap flux density with low harmonic content. Moreover, the regulation performance of the magnetic field and output voltage are investigated by three dimensional finite element analysis (3D FEA). The result indicates that ASHG has a high performance of adjusting terminal voltage. It can improve the generator efficiency, power density and stability comparing with the conventional vehicular generator.

Levitation force measurement on a switchable track for superconducting levitation systems

Whereas current superconducting levitation systems typically use permanent magnetic tracks, additional switchable components are required to realize fast turnouts or crossings. Therefore, a prototype for a switchable track segment was realized by a combination of permanent magnets with a superconducting coil, which enables switching of the magnetic field above the track from active (magnetic field is present) to inactive (significantly reduced magnetic field) and back. Previous studies of the magnetic flux density distribution above both track types showed only a small mismatch between the standard permanent magnetic setup and the new switchable design. Here, we present measurements of the levitation as well as of the lateral forces for both track types. The results show that the active switchable track leads to comparable force values as for the standard track. The differences lead only to a slight reduction of the levitation height above the switchable track. In contrast, the measured forces are significantly reduced, if the track is switched in the inactive mode, i.e. the values are no longer sufficient to maintain a stable levitation. Furthermore, a typical hysteresis for the force values was observed for both systems. The lateral asymmetry of the measured force values was traced back to inhomogeneities of the used superconductors.

Analytical Field and Torque Analysis of a Reaction Sphere

In recent years, the increasing need in small satellite solutions triggers the miniaturization of attitude control systems. Reaction spheres were proposed as promising replacements of conventional reaction wheels for their $4\pi $ rotations. Since the generated control torques could be about any desired axes, a single reaction sphere is sufficient for three-axis stabilizations of spacecraft. This paper presents an innovative design of reaction spheres. Its driving unit is a combination of permanent magnets (PMs) and electromagnetic induction. This enables the generation of torques about three principle axes simultaneously. Meanwhile, a contactless bearing is integrated into the actuator design. Detailed designs and working principles of the reaction sphere are described. To investigate performance characteristics of the actuator, field modeling is of great importance and provides the basis for dynamics modeling. In this paper, an improved analytical model for dynamic fields excited by slotless distributed windings is presented for the first time. To study the cross coupling between PMs and electromagnetic induction, the static field generated by PMs is also modeled analytically. These developed models are validated through comparisons with numerical simulations. Electromagnetic torques generated by the actuator are calculated through the approaches of the Maxwell stress tensor and the Lorentz force law. Torque calculations based on the analytical field models deviate from those based on the numerical model slightly, with the maximum error within 4%. This means the presented analytical models allow to predict the electromagnetic field distribution and torques precisely.

Field-Weakening Performance Improvement of the Yokeless and Segmented Armature Axial Flux Motor for Electric Vehicles

In order to avoid the unsafe operation and raise efficiency of yokeless and segmented armature axial flux motors at high speed, the control current of air gap flux is expected to be as small as possible with the same field-weakening effect. To reduce the control complexity, a new structure of module poles with a combination of permanent magnet and soft magnetic material is proposed, which has the characteristics of lower d-axis reluctance and a higher performance of yokeless and segmented armature axial flux motor with surface mounted permanent magnet. According to finite element analysis (FEA), the flux distributions of a rotor pole in no-load and demagnetization condition are contrasted, and under this new configuration, the derivative analytical models of back electromotive-force (EMF), electromagnetic torque, and air gap flux are validated, moreover, the influence of soft magnetic material of rotor poles on controlling the air gap flux is investigated in different load. Based on a particular objective function, the combination of permanent magnet and soft magnetic material is optimized. The results show that optimal solution of field-weakening performance of yokeless and segmented armature axial flux motors can be improved effectively and legitimately.

Electromagneto squeezing rotational flow of Carbon (C)-Water (H2O) kerosene oil nanofluid past a Riga plate: A numerical study.

This article predicts the electromagneto squeezing rotational flow of carbon-water nanofluid between two stretchable Riga plates. Riga plate is known as electromagnetic actuator which is the combination of permanent magnets and a span wise aligned array of alternating electrodes mounted on a plane surface. Mathematical model is developed for the flow problem with the phenomena of melting heat transfer, viscous dissipation and heat generation/absorption. Water and kerosene oil are utilized as the base fluids whereas single and multi-wall carbon nanotubes as the nanomaterials. Numerical solutions of the dimensionless problems are constructed by using built in shooting method. The correlation expressions for Nusselt number and skin friction coefficient are developed and examined through numerical data. Characteristics of numerous relevant parameters on the dimensionless temperature and velocity are sketched and discussed. Horizontal velocity is found to enhance for higher modified Hartman number.

Establishment of a biophysical model to optimize endoscopic targeting of magnetic nanoparticles for cancer treatment.

Superparamagnetic iron oxide nanoparticles (SPION) may be used for local tumor treatment by coupling them to a drug and accumulating them locally with magnetic field traps, that is, a combination of permanent magnets and coils. Thereafter, an alternating magnetic field generates heat which may be used to release the thermosensitively bound drug and for hyperthermia. Until today, only superficial tumors can be treated with this method. Our aim was to transfer this method into an endoscopic setting to also reach the majority of tumors located inside the body. To find the ideal endoscopic magnetic field trap, which accumulates the most SPION, we first developed a biophysical model considering anatomical as well as physical conditions. Entities of choice were esophageal and prostate cancer. The magnetic susceptibilities of different porcine and rat tissues were measured with a superconducting quantum interference device. All tissues showed diamagnetic behavior. The evaluation of clinical data (computed tomography scan, endosonography, surgical reports, pathological evaluation) of patients gave insight into the topographical relationship between the tumor and its surroundings. Both were used to establish the biophysical model of the tumors and their surroundings, closely mirroring the clinical situation, in which we could virtually design, place and evaluate different electromagnetic coil configurations to find optimized magnetic field traps for each tumor entity. By simulation, we could show that the efficiency of the magnetic field traps can be enhanced by 38-fold for prostate and 8-fold for esophageal cancer. Therefore, our approach of endoscopic targeting is an improvement of the magnetic drug-targeting setups for SPION tumor therapy as it holds the possibility of reaching tumors inside the body in a minimal-invasive way. Future animal experiments must prove these findings in vivo.

Wide-range tunable magnetic lens for tabletop electron microscope

A tabletop scanning electron microscope (SEM) utilizes permanent magnets as condenser lenses to minimize its size, but this sacrifices the tunability of condenser lenses such that a tabletop system can only be operated with a fixed accelerating voltage. In contrast, the traditional condenser lens utilizes an electromagnetic coil to adjust the optical properties, but the size of the electromagnetic lens is inevitably larger. Here, we propose a tunable condenser lens for a tabletop SEM that uses a combination of permanent magnets and electromagnetic coils. The overall dimensions of the newly designed lens are the same as the original permanent magnet lens, but the new lens allows the tabletop SEM to be operated at different accelerating voltages between 1kV and 15kV.