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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. [ABSTRACT FROM AUTHOR]

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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. [ABSTRACT FROM AUTHOR]

In this paper, adaptive proportional derivative (APD) parameter control was proposed to solve the problem of high power consumption caused by the unclear mechanism of liquid disturbance during the lifting-up of magnetic bearing in left ventricular assist devices. A mathematical model was derived that describes how the rotor operates in liquid filling. The disturbance caused by the liquid in the lifting-up process was analyzed, and an adaptive control system was developed to improve dynamic performance and reduce power consumption. The experimental results show that APD control requires a shorter rise time without overshoot of rotor displacement compared to traditional fixed configurations. When using the APD controller, the peak current dropped by 8%. The duration in which the current is greater than 1A was reduced by 10.2 ms, and the average current also dropped by 34%.

In order to predict the life of the auxiliary bearing in the design stage, it is crucial to calculate the friction heating power of the auxiliary bearing during the rotor drop process. In many cases, the auxiliary bearing has no lubrication or only solid lubrication. Therefore, the local method was chosen to calculate the friction power, focusing on analyzing the rolling elastic hysteresis power between the ball and raceway, the spin power of the ball and the differential sliding power between the ball and raceway. The calculation formulas of these powers were provided in this paper, along with the derivation of an analytical formula for the differential sliding power, which facilitates practical applications. These formulas are based on the quasi-static analysis and the raceway control theory. When the rotation speed of the inner ring of the auxiliary bearing, the radial force acting on the auxiliary bearing and the axial preloading force are all known, the friction heating power of the auxiliary bearing can be calculated by these formulas. The free drop experiment of an electromagnetic bearing high-speed motor without braking was carried out to test the calculation, under 3 000, 5 400, and 6 600 r/min. The rotor axis trajectory and the horizontal and vertical impact force acting on the auxiliary bearing were measured. The rotation speed of the inner ring of the auxiliary bearing was assumed to be the same as the speed of the rotor, calculated by the rotor axis trajectory. The radial force acting on the auxiliary bearing was calculated based on the horizontal and vertical impact force. The axial preloading force, which is about 410 N in this paper, was determined by the experimental data under 3 000 r/min with the method of trial calculation. With these parameters, the friction heating power of the auxiliary bearing was calculated, and compared with the change rate of the kinetic energy of the rotor observed in the experiment. It is found that the heating power calculated by the local method is approximately equivalent to the change rate of the kinetic energy, which proves the feasibility of the theoretical calculation. During the drop process of a non-lubricated auxiliary bearing, the spin of the ball generates the most heat, followed by the differential sliding between the ball and the raceway. The sum of the two accounts for the main part of the total heat, and the rolling elastic hysteresis between the ball and the raceway generates less heat.

Copyright of Journal of Xi'an Jiaotong University is the property of Editorial Office of Journal of Xi'an Jiaotong University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Relevance. In gas industry, the amount of equipment that has outlived its intended service life is increasing every year. In accordance with the law “On Industrial Safety of Hazardous Production Facilities,” compressor stations are dangerous objects, the reliable operation of which largely determines the condition of main gas pipelines. Technological pipelines of a compressor station are important objects of this system. They are subject to strict requirements due to the action of static and dynamic loads on them. Reliability of compressor stations is based on the results of a study of the condition of the object and the main factors affecting increased wear of equipment. The solution to wear problem is timely monitoring of equipment, in particular level measurement and determining the causes of pipeline vibrations using vibration diagnostics methods, and frequency and modal analysis methods. Aim. To study the causes of increased dynamic loads on the technological piping that arise during the operation of electric and gas pumping units at a compressor station using vibration monitoring methods. Methods. Vibration monitoring methods to analyze the causes of increased vibration values in the process piping of a compressor station with an electric gas pumping unit. Results and conclusions. The authors have measured vibration in a wide frequency band and assessed the technological condition of the main equipment of the compressor station with EGPA-6.3/8200-56/1.44-R based on the regulatory documentation STO Gazprom 2-2.3-324-2009. The main frequencies of the root-mean-square value of the vibration velocity, at which the highest vibration values were observed, were identified, and a modal analysis was performed using ANSYS software. Based on the results of natural studies and modal analysis, it was concluded about the occurrence of resonant high-frequency oscillations, multiple of the rotor rotation frequency.

Thermal power cycles using sCO2 as a working fluid place extreme demands on their turbomachinery components and their electric motors/generators. In this paper, new system topologies for sCO2 turbomachinery are proposed which take advantage of “bearingless” electric machine technology to improve performance. Bearingless motors/generators are a new type of electric machine which integrate the functionality of active magnetic bearings into the existing hardware of an electric motor/generator. The existing electromagnetic surfaces and materials are reused to enable controllable production of radial forces on the machine shaft. This is envisioned to improve hermetic direct-drive turbomachinery systems by either augmenting existing bearings (i.e., bearing assist) or replacing existing bearings (i.e., bearing removal). The state-of-the-art technologies for several bearing types (gas foil bearings, externally pressurized porous (EPP) gas bearings, and active magnetic bearings) and electric machines are reviewed to motivate the introduction of bearingless technology. Two system designs using bearingless machines are proposed and compared against existing commercial solutions in terms of maximum shaft weight, number of passthroughs into the hermetic environment, cost, and complexity. A case-study bearingless motor/generator is assessed via simulations and a hardware prototype to investigate practical considerations for using bearingless technology in sCO2 turbomachinery. The proposed bearingless solutions have potential to enable a new generation of sCO2 turbomachinery with improved reliability, reduced complexity, and lower cost. This paper shows that by transforming the motor/generator already present in turbomachinery into a bearingless motor/generator, the technical challenges involved with sCO2 can be overcome without adding significant cost.

Magnetic bearings are widely used in fields such as fluid machinery, aerospace, and marine vessels due to their properties of non-mechanical contact. Due to errors in manufacturing and assembly, unbalanced forces will be generated when the magnetic suspension rotors rotate, especially at high speed, which can easily cause strong vibration of the equipment. The control compensation algorithm of minimum displacement for the rotor is to adjust the control current of the magnetic bearing based on speed and unbalanced quantity, so that the rotor rotates around its centre of the geometric as much as possible, in order to reduce rotor displacement vibration and ensure the reliable and safe operation of the equipment. However, owing to the presence of speed changes and phase lag, it is necessary to continuously and repeatedly calculate the unbalanced compensation coefficient, which increases the computational complexity and affects the control effect of the magnetic suspension rotor. Therefore, this paper proposes a method based on LMS (Least Mean Square) and polynomial fitting to calculate the unbalanced compensation coefficient, obtaining the compensation amplitude and phase of the unbalanced vibration of the magnetic suspension rotor at different speeds, solving the problem of active unbalanced vibration control for the magnetic suspension rotor at any speed, and providing guarantee for the application of the magnetic suspension rotor in high-speed rotating machinery. [ABSTRACT FROM AUTHOR]

Bearings are pivotal components in mechanical systems, providing crucial support to rotating bodies. However, traditional bearings are susceptible to failure caused by friction and wear. This vulnerability is particularly pronounced in scenarios involving ultrahigh speeds and extreme conditions, necessitating the minimization of bearing losses and the enhancement of performance. Magnetic bearings, distinguished by their frictionless operation, absence of lubrication requirements, and high-speed capabilities, offer a promising solution to mitigate bearing failure attributable to friction. Nevertheless, a comprehensive review of magnetic bearings, encompassing their structural attributes, modeling mechanisms, and control strategies, is currently lacking in the literature. This paper aims to address this gap by conducting an exhaustive literature review on magnetic bearings. The objective is to provide scientists with a profound understanding of the structural characteristics, operational mechanisms, control performance, and future development trajectories of this technology. The paper begins by categorizing various magnetic bearings and conducting an in-depth analysis of their properties and characteristics, focusing on their magnetic circuit structures. Subsequently, it delves into the working principles and performance of mathematical models for magnetic bearings with different configurations, outlining the modeling procedures and optimization approaches. Additionally, the paper highlights the impact of control strategies on the performance of magnetic bearings. Modern control theory has demonstrated a remarkable 50% improvement in position accuracy and adjustment time compared to traditional PID control. Finally, the paper offers a glimpse into the future of magnetic bearing design, modeling mechanisms, and control strategies, presenting prospective directions for further advancements in this field. [ABSTRACT FROM AUTHOR]

Abstract The simulation of magnetic bearings involves highly non-linear physics, with high dependency on the input variation. Moreover, such a simulation is time consuming and can’t run, within realistic computation time for control purposes, when using classical computation methods. On the other hand, classical model reduction techniques fail to achieve the required precision within the allowed computation window. To address this complexity, this work proposes a combination of physics-based computing methods, model reduction techniques and machine learning algorithms, to tackle the requirements. The physical model used to represent the magnetic bearing is the classical Cauer Ladder Network method, while the model reduction technique is applied on the error of the physical model’s solution. Later on, in the latent space a machine learning algorithm is used to predict the evolution of the correction in the latent space. The results show an improvement of the solution without scarifying the computation time. The solution is computed in almost real-time (few milliseconds), and compared to the finite element reference solution.

The AMB-rotor system is complex and has strong coupling characteristics, which allows multi-harmonic disturbances to enter the system through different ways to produce vibrations with rich spectrum components, which has a great influence on the improvement of micro-vibration accuracy of the rotor system. To further achieve active control of the micro-vibration in the AMB-rotor system, firstly, the mechanism of multi-source disturbance is analyzed according to the working principle of the AMB-rotor system, and the mathematical and physical relationship between the mechanism of disturbance generation and the inducement is deeply studied. Then, the structure of a novel adaptive notch filter, the method of adaptive frequency estimation and analysis of harmonic current suppression in the AMB system are presented. Finally, simulation and experimental research using an MSCMG system demonstrate the feasibility of the proposed method regarding the elimination of harmonic control current.

Active magnetic bearings (AMBs) are widely used in different industries to offer non-contact and high-velocity rotational support. The AMB is prone to failures, which may result in system instability and decreased performance. The efficacy and reliability of magnetic bearings can be significantly affected by failures in the sensor and control systems, leading to system imbalance and possible damage. A digital twin is an advanced technology that has been increasingly used in different industrial fields. It allows for the creation and real-time monitoring of virtual replicas of physical systems. This paper proposes a novel method for fault detection of Active Magnetic Bearings (AMBs) using digital twin technology and a neural network. The digital twin model serves as a virtual representation that accurately replicates the actual AMB system's efficiency and features, allowing continuous real-time monitoring and detection of faults. The conventional neural network (CNN) is used as the primary tool for identifying faults in the Active Magnetic Bearing (AMB) within a digital twin model. Experiments proved the effectiveness and robustness of the suggested approach method to fault detection in the AMB. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The continuous strengthening of environmental regulations is expected to have a significant impact on the vessel operations of shipping companies. Each country must reduce greenhouse gas emissions from ships operating in domestic coastal areas to meet its Nationally Determined Contributions (NDC). For new vessels, we are assessing potential emission reductions through various technologies, recognizing that transitioning to alternative fuels is inevitable to achieve our ultimate goal of zero emissions. However, the introduction of alternative fuels for ships involves numerous challenges, including the overall replacement of propulsion systems, etc. Additionally, to ensure that existing ships can comply with the gradually increasing environmental regulations, the immediate adoption of bridge technologies that can be applied is essential. Rotor sails are recognized as a technology that can be installed on both new ships and vessels in operation, offering carbon emission reductions through thrust assistance. Rotor sails have traditionally been mainly employed on ocean routes with consistent wind patterns. In this paper, we conducted a review of the feasibility of operating rotor sails in coastal areas where wind direction frequently changes and wind intensity is not constant. Particularly, a concept of a rotor sail with magnetic bearings for the rotor sail system, utilizing the principle of magnetic levitation, is suggested. The reduction in frictional forces during rotor sail operation contributes to increased maintainability and advantages in terms of noise and vibration. Specifically, in this study, a structural design for minimizing weight for optimal performance has been carried out. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Vibration, Measurement & Diagnosis is the property of Nanjing Hangkong Daxue and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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.

In this study, a novel magnetic suspension flywheel battery with a multi-function air gap is proposed. Based on the unique multi-function air gap, the degrees of freedom between the control magnetic circuits can be independent of each other, reducing the coupling effect between degrees of freedom. The proposed flywheel battery system topology inherits the unique advantages of the magnetic suspension flywheel battery. However, due to the breakthrough of the overall topology in the air gap, flywheel, and protection measures, the system has more advantages in the precise design of the magnetic circuit, decoupling, high-stability control, and energy storage. First, the advantages, geometric characteristics, and magnetic circuit of the flywheel battery system are introduced and analyzed. Then, the position and length of the multi-function air gap and conventional air gap in the magnetic circuit are optimized to ensure the best magnetic performance of the entire magnetic circuit. Then, the flywheel, motor, and protection settings are introduced in detail. Finally, performance tests are conducted, and the good experimental results show that the proposed flywheel battery has good anti-interference ability and decoupling ability. [ABSTRACT FROM AUTHOR]

This article presents the results of the work on the creation of an experimental plant, its testing, as well as the development of a computational model of a rotor magnetic suspension with the use of axial electromagnets. The main purpose of producing the plant was to test the results of the developed numerical finite element model. An automatic control system was developed for the experimental installation. The electrical circuit was assembled on the basis of a ESP32 microcontroller with a clock frequency of 240 MHz and a PWM with a capacity of 10 bits. A PID-regulator program was developed. The coefficients kP, kD, kI used in the code of the electronic control system program (PID-controller) were selected. An experimental study of the bearing capacity of the axial active magnetic bearing under the influence of an external axial force was conducted. The required power of the axial active magnetic bearing was determined. The maximum load-bearing capacity of the installation for the selected coefficients of the PID-controller was determined. An axisymmetric finite-element model of the axial active magnetic bearing was created in the open-source program FEMM 4.2. The load-bearing capacity of the installation for a given current intensity value was calculated. The results of the numerical modelling were compared with the experimental data obtained. The basic principles of creation and operation of the experimental plant and its numerical model are outlined.

With the increasingly widespread application of magnetic bearings (MBs) in high-speed motors, turbomachinery, and machine tools, the development of magnetic bearing controllers (MBCs) is becoming increasingly significant. Conventional MBCs are designed specifically for a particular type of MB and have poor generality. Given this, an MBC with a digital signal processor (TMS320F28377S) as the core is developed. Meanwhile, a generality calculation method for the circuit module is proposed. The displacement conditioning circuit designed in this paper can match most MB displacement sensors, and the generality is improved to 91.66%. The designed power amplifier can realize the switching of two-level and three-level pulse width modulation (PWM). It can also realize the switching of unidirectional and bidirectional power amplifier control. Therefore, it can apply to most MB rotor systems, and the generality is improved to 66.67%. In addition, the proposed dual closed-loop control strategy based on linear active disturbance rejection control (LADRC) makes the system’s anti-interference capability, robustness and self-adaptive capability enhanced, further improving the generality of the controller. Simulation and experimental results show that the MBC is highly general and has good dynamic performance, and the electrical control system of the MB is optimized.

Instabilities such as stall and surge have been widely studied in open loop gas turbine system for several decades. However, researches on instabilities in a closed loop are limited. Especially, no experimental investigation in a supercritical CO2 compressor has been performed thoroughly before. An integral test loop equipped with a turbo-alternator-compressor using active magnetic bearing was utilized to study the instabilities in a supercritical CO2 compressor. The compressor performance testing was conducted including near stall and surge operating conditions. The mass flow rate of compressor was greatly reduced even beyond surge limit and pressure was measured with high frequency transducer to observe the characteristics. It was observed that as the inertia of the system was changed by altering the compressor inlet conditions, the characteristics of the supercritical CO2 compressor in unstable operating conditions also vary. This can be qualitatively explained by using the theory Greitzer proposed previously.