Magnetic Bearing Research Articles

Energy-saving and economic analysis of the data center cooling system using magnetic bearing chillers under different climate conditions

Magnetic bearing chiller has excellent Coefficient of Performance, but the high initial investment makes it challenging to find a balance between energy-saving efficiency and economic potential. This paper proposes two energy-saving retrofits with water-side economizers, using efficient centrifugal chillers (Plan 1) and magnetic bearing chillers (Plan 2), respectively, to replace the existing cooling system of a case data center in Nanchang. Energy models of three cooling systems are developed to analyze the energy efficiency and performance. Compared to the existing cooling system, the operation time of Full free cooling and Partial free cooling for Plan 1 and Plan 2 reach 2489 and 1324 h, respectively. Result in energy savings of 63.19 % and 64.54 %, and power usage effectiveness reduce 0.341 and 0.349, respectively. Because the annual chiller COP of Plan 2 is 6.7 % higher than that of Plan 2, Plan 2 saves additional 3.96 % annual energy consumption compared to Plan 1. Furthermore, the energy-savings and economy of the retrofit plans in five typical climate cities in China are discussed. The energy savings rates for Plan 1 and Plan 2 are 61.4%–64.7 % and 62.1%–65.6 %, respectively, and their dynamic payback periods are 2.02–5.15 years and 2.16–5.6 years.

Analysis of False Alarms on DVOR Equipment at I Gusti Ngurah Rai International Airport

According to the Government Regulation of the Republic of Indonesia No.71 of 1996 concerning Airports article 9 Paragraph (1) it is explained that flight navigation facilities can include Non Directional Beacons (NDB), Doppler VHF Omni Range (DVOR), Instrument Landing System (ILS), Radio Detection and Ranging (RADAR). Airports must provide navigation facilities, especially the Doppler VHF Omni Range (DVOR), which is a flight aid that has unlimited (continuous) capabilities, and transmits combined radio signals, including Morse code and data that can enable receiver equipment on aircraft to acquire magnetic bearings. from the station to the airplane using the frequency due to the doppler effect, not the actual azimuth direction to the aircraft but information about the Doppler VHF Omni Range (DVOR) ground station point at I Gusti Ngurah Rai Airport. This study used a qualitative descriptive method with physical checking at the Denpasar Branch of Perum LPPNPI, there was an alarm on the Doppler VHF Omni Range (DVOR) equipment caused by a lightning strike which could not be controlled using LMMS due to failure in several modules. So researchers need to replace several modules affected by the Alarm, namely the LCU (Local Control Unit), CSU (Control Sector Unit), and ASU (Air STARTER UNIT) and do the finishing by checking the power and settings on the monitor, resulting in a Doppler VHF Omni Range (DVOR) adjustment. back to normal.

Principle, Modeling and Experiment of a New Axial-Type Superconducting Magnetic Bearing With Superconducting Coil

Principle, Modeling and Experiment of a New Axial-Type Superconducting Magnetic Bearing With Superconducting Coil

Adaptive Proportional Derivative Control for Magnetic Bearing in Full Maglev Left Ventricular Assist Device

Adaptive Proportional Derivative Control for Magnetic Bearing in Full Maglev Left Ventricular Assist Device

Radial and axial integrated inductive displacement sensor used for magnetic bearing system

This paper presents a small size and high-integration inductive displacement sensor used for magnetic bearings. This sensor is a circular ring structure fixed on radial direction of a magnetic bearing and can measure radial and axial displacement at the same time. Sensitivity results show that displacement detection along each direction will not be affected by others. Then, the proposed sensor is applied in closed-loop control of a magnetic bearing when the rotor is levitated and rotates at 40k, 50k, and 60k r/min. According to experiment results, radial and axial displacement vibrate noise can be controlled within ±10 μm and about ±10 μm, respectively, evaluating the feasibility of inductive displacement sensor in closed-loop control. Contribution of this paper is to explore application boundary and provide a guide of applicable speed for inductive displacement sensor, which will help to promote application of magnetic bearing in more fields. And based on the experiment results present in this paper, inductance sensor can be used for magnetic bearing control when the rotation speed is below 60k r/min.

Control the Axial Displacement of the Rotor Position with Load and No Load Condition in an Active Magnetic Bearing System

Control the Axial Displacement of the Rotor Position with Load and No Load Condition in an Active Magnetic Bearing System

Dynamic Analysis and PD Control in a 12-Pole Active Magnetic Bearing System

This paper conducts an in-depth study on the dynamic stability and complex vibration behavior of a 12-pole active magnetic bearing (AMB) system considering gravitational effects under a PD controller. Firstly, based on electromagnetic theory and Newton’s second law, a two-degree-of-freedom control equation of the system, including PD control terms and gravitational effects, is constructed. This equation involves not only parametric excitation, quadratic nonlinearity, and cubic nonlinearity but also a more pronounced coupling effect between the magnetic poles due to the presence of gravity. Secondly, using the multi-scale method, a four-dimensional averaged equation of the system in Cartesian and polar coordinates is derived. Finally, through numerical analysis, the system’s amplitude–frequency response, motion trajectory, the relationship between energy and amplitude, and global dynamic behaviors such as bifurcation and chaos are discussed in detail. The results show that the PD controller significantly affects the system’s spring hardening/softening characteristics, excitation, amplitude, energy, and stability. Specifically, increasing the proportional gain can quickly suppress the rotor’s motion, but it also increases the system’s instability. Adjusting the differential gain can transition the system from a chaotic state to a stable periodic motion.

Analysis of a passive vibration damper for high-speed superconducting magnetic bearings

Superconducting magnetic bearings (SMB) based on a combination of high temperature superconductors and permanent magnets enable the realization of self-stabilized high-speed devices with significantly reduced friction. However, external vibration might couple in the bearing resulting in large amplitude oscillations due to a resonance case. A dedicated eddy current damper (ECD) might be used to eliminate these oscillations for a stable operation. The influence of such damping elements was studied for a frictionless SMB twisting system designed to speed up the conventional ring spinning process. Therefore, conductive copper rings with different thicknesses were implemented at different positions into the bearing setup as ECD. Afterward, the SMB setup was analyzed during acceleration using an array of laser distance sensors to record the displacement of the levitating permanent magnet ring in radial and axial direction, respectively. Simultaneously, a numerical model was developed to investigate the influence of the ECDs on the dynamic and static behavior of the SMB in more detail. It was shown that the simulated damping coefficients are in good agreement with the measured values, which allows further optimization of the ECD with the developed numerical model.

Comparative analysis of the 4-pole and 8-pole radial magnetic bearings with permanent magnets

Comparative analysis of the 4-pole and 8-pole radial magnetic bearings with permanent magnets

Preliminary Study on Recontrol Evaluation of a Magnetic Bearing Rotor Falling on Touch-Down Bearings

The dynamic control of an active magnetic bearing (AMB) rotor after the rotor falls to its touch-down bearings has always been a difficult problem for applications such as flywheel energy storage. The rotor drop process has obvious nonlinear dynamic characteristics. This paper first discusses the structure of AMBs and the basic principles of their control. Starting from the electromagnetic forces that electromagnets can provide, the problem is simplified to the influence of an electromagnetic force with constant damping characteristics on the dynamic characteristics of a dropped rotor. A dynamic model of an AMB rotor with touch-down bearings was built and the contact force model between the rotor and the touch-down bearings was determined. A constant damping electromagnetic force was applied in two ways to verify the dynamic control feasibility of a dropped rotor through magnetic bearings. The simulation results show that the dropped rotor recovery control is feasible by applying a reasonable electromagnetic force.

Multi-objective optimization of bias current coefficient based on NSGA- III for active magnetic bearing with redundant electromagnetic actuators

PurposeThe multi-objective optimization configuration strategy is proposed due to the configuration of EMAs in fault-tolerant control of active magnetic bearing with redundant electromagnetic actuators involving high-dimensional, nonlinear, conflicting goals.Design/methodology/approachA multi-objective optimization model for bias current coefficients is established based on the nonlinear model of active magnetic bearings with redundant electromagnetic actuators. Based on the non-dominated sorting genetic algorithm III, a numerical method is used to obtain feasible and non-inferior sets for the bias current coefficient.Findings(1) The conflicting relationship among the three optimization objectives was analyzed for various failure modes of EAMs. (2) For different EMAs' failure modes, the multi-objective optimization configuration strategy can simultaneously achieve the optimal or sub-optimal effective EMF, flux margins, and stability of EMF. Moreover, the characteristics of the optimal Pareto front are consistent with the physical properties of the AMB. (3) Compared with the feasible configuration of C0, the non-inferior configurations can significantly improve the performance of AMB, and the advantages of the multi-objective optimization configuration strategy become more prominent as the asymmetry of the residual supporting structure intensifies.Originality/valuei) Considering the variation of the rotor displacement during the support reconstruction, a decision-making model that can accurately characterize the dynamic performance of AMB is presented. (ii) The interaction law between AMB and rotor under different failure modes of EMAs is analyzed, and the configuration principles for redundant EMAs are proposed. (iii) Based on the dynamic characteristics of AMB during the support reconstruction, effective EMF, energy consumption, and the Pearson correlation coefficient between the desired EMFs and the decoupled control currents are used as objective functions. iv. The NSGA-III is combined with the decision-making model to address the multi-objective optimization configuration problem of C0.

Measurement-based Dynamic Modelling in Levitated Active Magnetic Bearing Systems

Commissioning Active Magnetic Bearings (AMB) requires a well-designed control system to reject external disturbances while supporting process loads. An accurate dynamic model is essential for predicting responses to various excitations and disturbances, aiding in controller design. Current models for AMB commissioning are either nonparametric estimations, which provide limited information, or finite element models, which may not capture all system dynamics. This paper presents a black-box method to develop a parametric model that captures all dynamics within an AMB system using measurement data. Frequency domain measurement data was used to construct a segmental linear model to simulate dynamic interactions. The controller, actuation, and sensor components were derived from SKF Magnetic Mechatronics design calculations to isolate the rotor from the plant model and reconstruct the closed-loop system model. The frequency response of the identified rotor model was compared to direct measurements, and the resulting system model was compared to direct measurements of the closed-loop response. Results show that the proposed segmental AMB system model predicts frequency response with 97.9% accuracy compared to direct measurements. This model will be used to design control methods to improve AMB system performance.

Hyperloop New Mode of Transportation

Today conventional mode of transportation is rail, road, water, and air. These modes of transport are relatively slow and expensive or a combination of relatively slow and expensive. Hyper loop is latest mode of transportation which is fast and inexpensive to change the pattern of transportation. Similar to Linux, hyper loop is also open and unique design concept. By bringing this concept to reality, it will help people to travel from one city to another city in a very small time and also at a low cost. The hyper loop capsule would accelerate with the help of linear electric motor and traverse through the tube at a high speed. By using passive magnetic levitation or air bearing, capsule will run above their track. Hyper loop consists of a low-pressure tube with capsules that are travelled at low and high speed throughout the length of the tube. The capsules are supported with the help of cushion of air. To accelerate the capsules the magnetic linear accelerator is fitted at various stations on the hyperloop tube. To enter and exit the passengers the passage may be left either at the end of the tube or branches along the tube length. Let's see how the hyperloop change mode of transportation.

Fuzzy gain scheduled adaptive sliding mode control of a vertical shaft hybrid magnetic bearing under variable rotor speeds

Fuzzy gain scheduled adaptive sliding mode control of a vertical shaft hybrid magnetic bearing under variable rotor speeds

A novel approach for sensitivity improvement of axial inductive displacement sensor

Nowadays, magnetic bearing has been used in more and more fields. Displacement sensor is one of the most important functional components of a magnetic bearing system and have attracted more and more attentions. Inductance displacement sensor, which shows merits in maintainability, lifetime, sensitivity, environmental interference ability, and cost, is a potential displacement sensor for magnetic bearing systems. While, usually, for a certain application, installation space of displacement is limited, increasing the difficulty of sensitivity improvement by stator structure optimization. This paper presents a novel approach for axial inductance displacement sensor to improve sensitivity by decreasing the armature depth. In the experiment part, three armature with different depth have been fabricated and their performance are tested. The results show that sensitivity is improved from 2.34 mV/µm to 3.15 mV/µm when the depth of armature decreases from 24 mm to 18 mm, validating the feasibility of sensitivity improvement by decreasing the armature depth. With the improvement of sensitivity, resolution also improves from 5.1 µm to 3.8 µm. Negative effect of this approach is that measuring range is decreased when the armature depth is reduced.

Modeling and analysis of a novel 6-DOF magnetic levitation system with experimental verification

To improve the uniformity of magnetic flux and increase the stroke of the magnetic levitation system, this paper designs a novel 6-DOF magnetic levitation system and proposes an improved novel Halbach array. First, a repulsive passive magnetic bearing is utilized to provide levitation force, leading to a noticeable reduction in levitation power consumption. Then, a magnetic circuit model for the magnetic levitation system is established, and the improved novel Halbach array is optimized based on this model. Next, the stable levitation model and measurement model for the system are established, and the magnetic field distribution and magnetic bearing stiffness are analyzed. Results indicated an increase of 0.1[Formula: see text]T in the maximum magnetic flux density, accompanied by an improvement in the uniformity of magnetic flux. Additionally, there is an enhancement of 10% in magnetic bearing stiffness. Finally, a prototype of the system is constructed, and the stable levitation simulation and experiment of the actuator are conducted with this system. The maximum levitation absolute displacement error obtained by simulation is about 655[Formula: see text]nm, and the experimental results exhibited a maximum levitation absolute displacement error of approximately 750 nm for the system, confirming the effectiveness of the proposed modeling method.

Estimation of magnetic levitation and lateral forces in MgB2 superconducting bulks with various dimensional sizes using artificial intelligence techniques

The advent of superconducting bulks, due to their compactness and performance, offers new perspectives and opportunities in many applications and sectors, such as magnetic field shielding, motors/generators, NMR/MRI, magnetic bearings, flywheel energy storage, Maglev trains, among others. The investigation and characterization of bulks typically relies on time-consuming and expensive experimental campaigns; hence the development of effective surrogate models would considerably speed up the research progress around them. In this study, we first produced an experimental dataset containing the levitation and lateral forces between different MgB2 bulks and one permanent magnet under different operating conditions. Next, we have exploited the dataset to develop surrogate models based on Artificial Intelligence (AI) techniques, namely Extremely Gradient Boosting, Support Vector Regressor (SVR), and Kernel Ridge Regression. After the tuning of the hyperparameters of the AI models, the results demonstrated that SVR is the superior technique and can predict levitation and lateral forces with a worst-case accuracy scenario 99.86% in terms of goodness of fit to experimental data. Moreover, the response time of these models for the estimation of new datapoints is ultra-fast.

Bulk MgB2 Superconducting Materials: Technology, Properties, and Applications.

The intensive development of hydrogen technologies has made very promising applications of one of the cheapest and easily produced bulk MgB2-based superconductors. These materials are capable of operating effectively at liquid hydrogen temperatures (around 20 K) and are used as elements in various devices, such as magnets, magnetic bearings, fault current limiters, electrical motors, and generators. These applications require mechanically and chemically stable materials with high superconducting characteristics. This review considers the results of superconducting and structural property studies of MgB2-based bulk materials prepared under different pressure-temperature conditions using different promising methods: hot pressing (30 MPa), spark plasma sintering (16-96 MPa), and high quasi-hydrostatic pressures (2 GPa). Much attention has been paid to the study of the correlation between the manufacturing pressure-temperature conditions and superconducting characteristics. The influence of the amount and distribution of oxygen impurity and an excess of boron on superconducting characteristics is analyzed. The dependence of superconducting characteristics on the various additions and changes in material structure caused by these additions are discussed. It is shown that different production conditions and additions improve the superconducting MgB2 bulk properties for various ranges of temperature and magnetic fields, and the optimal technology may be selected according to the application requirements. We briefly discuss the possible applications of MgB2 superconductors in devices, such as fault current limiters and electric machines.

Stability Assessment of the High-Speed Flywheel with AMBs on a Rotating Platform

With the continuous improvement of the performance and capabilities of spacecrafts, the application of active magnetic bearings (AMBs) has become a major focus in current research. The AMBs-flywheel system is not only responsible for attitude control but also provides the required energy during shadow periods. In magnetically suspended single gimbal control moment gyroscope (SGCMG), self-excited vibration caused by high-speed rotor rotation significantly affects the stability of the AMB system. The research focus lies in magnetically supporting the flywheel at high speeds with low power consumption to explore gyroscopic mechanics at ultra-high speeds and assess the corresponding stability. This study presents an assessment of the stability performance of a high-speed flywheel equipped on a single gimbal with an angular momentum of 75 Nm. To achieve ultra-high-speed operation under low driving power, a high-precise dynamic balance was performed followed by a novel unbalance control strategy of a radial and axial automatic balancing algorithm to suppress effectively synchronous vibrations due to nutation and precession. Corresponding experiments including static stable suspension experiments as well as low-speed, high-speed, and series-based stability assessments were conducted. Stable suspension at any speed ranging from 0 to 30,000 r/min was successfully implemented. The stability performance of the high-speed flywheel on a rotating platform at different gimbal speeds was verified, with a maximum speed reaching 31,200 r/min. The entire output torque process within the range of 30,000 r/min was revealed.

Comparative study of passive magnetic bearing using four ring magnets: a critical review

Researchers on reducing energy losses caused by friction in small-scale wind turbines. This is crucial because a significant amount of energy is wasted due to friction in the main roller bearing. In order to overcome this, the concept of levitation has gained popularity. Levitation is achieved by employing the repelling forces between two opposing poles of a permanent magnet (PM), significantly reducing friction between the turbine stator and rotor. As a result, the overall energy production of the turbine increases. The use of passive permanent magnet bearings has several disadvantages, such as limited load-bearing capacity and rigidity. To address these limitations, we conducted numerical studies on four different configurations in order to enhance load-bearing capacity and stiffness. The results showed that the radial configuration outperformed the axial-type configuration in terms of stiffness and load-bearing capabilities in all four arrangements. Furthermore, it was revealed that radial passive magnetic bearings with adequate air gaps are not only more efficient but also less expensive than employing iron cores at the rear and between ring magnets for small-scale wind turbines.