Rotor Eccentricity Research Articles

An Improved Conformal Mapping Method for Electromagnetic Vibration Analysis in PMSMs With Rotor Eccentricity

An Improved Conformal Mapping Method for Electromagnetic Vibration Analysis in PMSMs With Rotor Eccentricity

Vibration compensation control strategy of composite cage rotor bearingless induction motor based on fuzzy coefficient adaptive-linear-neuron method

To address the vibration problem induced by rotor eccentricity in a composite cage rotor bearingless induction motor(CCR-BIM), a vibration compensation control approach based on the fuzzy coefficient adaptive-linear-neuron is proposed. Firstly, the CCR-BIM mathematical model and the mechanism of unbalanced vibration are investigated, obtaining the expression of rotor displacement when the rotor is unbalanced. Afterwards, the displacement is decomposed by the fuzzy coefficient adaptive-linear-neuron algorithm to obtain the harmonic component related to vibration, and the value range of the weight coefficient is determined using stability analysis. Furthermore, through analyzing the shortcomings of the traditional PID vibration compensation method, a rotor vibration compensation method based on the fuzzy coefficient adaptive-linear-neuron is put forward to achieve high-performance vibration compensation control. Finally, the PID method and the proposed fuzzy coefficient adaptive-linear-neuron algorithm are simulated and verified by experiments. The findings demonstrate that the proposed algorithm successfully not only suppresses rotor unbalanced vibration but also exhibiting great dynamic performance.

Impact of 2D and 3D Rotor Eccentricity on End Winding Mechanics Behavior in Synchronous Generators

Impact of 2D and 3D Rotor Eccentricity on End Winding Mechanics Behavior in Synchronous Generators

Method for vibration suppression in rotary machines using multiple automatic ball balancers

An automatic ball balancer (ABB) is a device that is used to automatically balance an eccentric rotor; these are typically used in rotary machines with unknown or variable imbalances. The typical construction of an ABB consists of several balls in a ring race. The balls can move freely inside the race, which changes the eccentricity radius and phase angles relative to the rotor. The automatic balancing process requires an ABB unit to be installed on an eccentric rotor's axis; thus, its application is quite limited and usually requires the redesign of a rotary machine. This paper presents a new method for eliminating vibrations in rotary machines by using multiple ABBs that are mounted away from the rotor's axis. In this application, ABBs can be considered to be unbalanced rotary masses with adjustable eccentricity radii and phases. Theoretically, this ability allows for the total reduction of the inertial force from an eccentric rotor; however, the parameters of the ABBs must be set correctly. The process of setting the eccentricity radius and phase in each ABB occurs due to a self-synchronization phenomenon and generally depends on the physical parameters of either a rotary machine or ABBs. Both analytical and numerical investigations that were based on the mathematical model of a system of a rotary machine with a pair of ABBs allowed us to formulate basic rules to apply such a system in existing rotary machines without interference on the rotors.

Torque Performance Analysis of Asymmetric Magnetic Pole Permanent Magnet Synchronous Motor for New Energy Vehicles

In view of the problem of large torque ripple and poor output performance of permanent magnet synchronous motor, a new topology of asymmetric magnetic pole permanent magnet synchronous motor is proposed, and the torque ripple of this motor structure and the suppression method are analyzed. First, the equivalent magnetic circuit method and Lorentz force law are used to derive the analytical formula of torque ripple of the motor. Then, based on the analytical formula, the parameters of permanent magnet of the asymmetric magnetic pole permanent magnet synchronous motor are optimized and verified by finite element software simulation; on this basis, the method of rotor eccentricity is used to further weaken the torque ripple of the motor, and the optimal eccentricity distance is analyzed. The research shows that when the parameters of the magnetic pole of the asymmetric magnetic pole permanent magnet synchronous motor is appropriate, the harmonic content of the air gap magnetic density of the optimized motor is greatly reduced, and the motor has good output characteristics, and the torque ripple is reduced to 5.4%. Finally, the prototype is trial‐manufactured and tested. The results show that after optimization, the cogging torque of the motor is reduced, the torque output performance is improved, and the overall motor performance is improved. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Self-powered sensor for online monitoring of eccentricity faults in rotating machinery and its application in spindle eccentricity monitoring of machine tools

With their unique structures and functionalities, rotating machineries are widely employed in various high-end industries. However, eccentric faults of rotors during continuous high-speed operation represent a critical factor in causing safety accidents. Therefore, real-time monitoring of rotor health is crucial for promptly identifying potential safety hazards and fault indications, enabling preventative maintenance, and enhancing safety performance. Nonetheless, traditional monitoring methods rely on sensors installed on rotating components, which are prone to interference in rotational environments, involve complex installation and maintenance procedures, and pose significant challenges to rotor health monitoring. In this study, a self-powered rotor eccentricity monitoring sensor (RE-TENGs) is designed and fabricated, integrating triboelectric nanogenerator technology. This sensor utilizes the rotor as the self-sensing entity, requiring no external power supply and featuring simplified installation, enabling real-time monitoring of rotor health during rotational machinery operation. A linear relationship between the RE-TENG's eccentric response and electrical characteristics was established through dynamic testing. Furthermore, the actual eccentricity orientation of the rotor was successfully determined by employing vector analysis and synthesis methods with multiple RE-TENGs coupled. To further validate the practicality and accuracy of RE-TENGs, a monitoring testbed for eccentric faults of the spindle rotor in a CNC machine tool was constructed, with the spindle rotor's eccentric fault simulated through misaligned installation. Experimental results demonstrate that RE-TENGs can effectively detect rotor faults induced by eccentric forces during the actual operation of machine tools, accurately determining the eccentric direction and displacement. With an actual angle recognition error of less than ±0.824° and an eccentric distance recognition accuracy exceeding 98 %, the exceptional performance of RE-TENGs in monitoring and precise identification of eccentric faults in rotating machinery rotors is unequivocally verified. By integrating triboelectric nanogenerator (TENG) technology, this study realizes real-time monitoring and precise identification of eccentric faults in rotating machinery rotors. It provides a novel solution for health condition monitoring of rotating machinery and offers a reference for overcoming the cumbersome installation and complex wiring of traditional sensors in practical applications.

Effects of air gap eccentricity on different rotor structures for PMSM in electric vehicles

In addition to research related to static eccentricity and dynamic eccentricity examining fault and diagnostic methods in various types of motors, there are also studies conducted for motors with non-uniform air gaps similar to the condition. In these studies, improvements and changes in motor performance for such types of motors can be observed. In this study, the effects of the rotor structures determined in the study and the air gap shape, which is effective by changing the eccentricity ratio, on the motor performance of the interior permanent magnet synchronous motor designed for electric vehicle applications are examined. Besides the elliptical rotor structure, which is widely researched in dynamic eccentricity studies, these eccentric motor structures also include novel rectangular and polygonal eccentric rotor structures. Motor models with non-uniform air gap structures are designed in two dimensions and subjected to simulation and analysis studies using the finite element method. At the end of the study, along with the parameters identified for motor performance, the harmonic components of the stator current, radial air gap flux density and the output torque obtained through Fast Fourier Transform analysis have been provided.

Improved air gap permeance modelling for single-slice magnetic equivalent circuits of skewed induction motors

PurposeWhen rotor and stator teeth are close, the connecting air gap flux tube's cross-sectional area exceeds the tooth overlap area. This flux fringing effect is disregarded in the air gap permeance calculation of single-slice magnetic equivalent circuits (MECs) of electric motors with skewed rotors. This paper aims to extend an air gap permeance calculation method incorporating flux fringing for unskewed rotors to skewed and radially eccentric rotors.Design/methodology/approachAssuming axial independence, the unskewed air gap permeance is rotated according to the skew and integrated along the axial dimension, resulting in a first method. The integral is approximated analytically, resulting in a second method. Results are compared to a commonly used reference method and validated using a non-linear finite element method (FEM) simulation.FindingsThe proposed methods provide better alignment with the FEM validation compared to the reference method for skewed rotors and common rotor eccentricity, i.e. below 50% of the air gap length. The analytical method is shown to be competitive with the reference method regarding computational time cost.Originality/valueTwo novel air gap permeance methods are proposed for single-slice MECs with skewed rotors. Their characteristics are discussed and validated.

Thermally stable modification of PEO‐based all‐solid‐state electrolytes via a stretching flow field: Constructing a supportive polymer skeleton

AbstractSince the advent of all‐solid‐state lithium‐ion batteries (ASSLIBs), they have been widely regarded as the ideal high‐temperature‐resistant energy storage devices. The solid‐state electrolyte, a crucial component, should possess high ionic conductivity, excellent flexibility, and significant mechanical strength. Poly(ethylene oxide)‐based all‐solid‐state polymer electrolytes (PEO‐ASSPE) appear to meet these criteria. However, PEO‐ASSPE exhibits poor stability at elevated temperatures, where localized overheating and internal thermal runaway can lead to battery short‐circuit failure. To address these issues, this study employs a ethylene‐methacrylic acid copolymer (EMAA) as a structural support polymer, blended via a eccentric rotor mixer. The homogeneously dispersed EMAA within the PEO matrix forms an interpenetrating network structure and interacts with other components, significantly enhancing the high‐temperature electrochemical stability of the composite polymer electrolytes (CPEs) while maintaining ionic conductivity. Research has demonstrated that when the EMAA content is 40 wt.%, the resulting CPE‐40EMAA exhibit high ionic conductivity (4.07 × 10−4 S cm−1), a high lithium‐ion transference number (0.564), a broad electrochemical stability window (5.1 V), and excellent high‐temperature lithium metal cycling stability (stable cycling for 800 h at current density of 0.1 mA cm−2), which sufficiently meets the electrochemical performance requirements for ASSPEs in high‐temperature energy storage batteries.

Rotor Eccentricity Quantitative Characterization Based on Physics-Informed Adversarial Network and Health Condition Data Only

Rotor Eccentricity Quantitative Characterization Based on Physics-Informed Adversarial Network and Health Condition Data Only

Research on unbalanced characteristics of axial-varying eccentric rotor based on signal demodulation

In the presence of non-uniform loads, rotor misalignment emerges as a prevalent fault in permanent magnet synchronous motors (PMSMs), leading to the manifestation of an axial-varying eccentric air–gap. Considering the three-dimensional (3D) nature of magnetic flux under axial-varying eccentric fault, 3D finite element (FE) analysis method was used in this paper. Then, the electromagnetism simulations were conducted to calculate the magnetic flux density and unbalanced magnetic pull (UMP). With the signal demodulation algorithm based on principal component analysis (DPCA), the frequency modulation of various signals from simulation and experiment was extracted. Furthermore, based on the modulation features, the relevance among magnetic flux density, UMP, and vibration acceleration was established with shaft frequency as the link. The coupling of magnetic field and vibration level shown in results was analysis, which provide important theoretical and engineering references for the safe operation of PMSM system and the exact identification of rotor tilting faults.

Dynamic investigation of the electromechanical coupling system in a permanent magnet direct-drive locomotive under rotor eccentricity faults

In the traction system of a direct-drive locomotive, the gearbox design is eliminated, enabling the direct transmission of output torque from the traction motor to the wheelset. Due to this unique structure, rotor eccentricity, which is a common fault in traction motors, can have a direct impact on the dynamic performance of key components such as the motor, bogie, and wheelset in locomotives. In order to investigate the dynamic response of the direct drive locomotive under rotor eccentricity faults, a comprehensive electromechanical coupling model that considers the dynamic motion of the rotor is established in this paper. The coupling effect between the mechanical system and the electrical system, as well as the dynamic forces induced by rotor eccentricity, are taken into account in the model. The simulation results reveal that ripple torque has an obvious effect on rotor dynamics behaviour, while rotor air-gap eccentricity and mass eccentricity exhibit varying degrees of influence on the dynamic performance of the vehicle system. Furthermore, the influence laws of rotor eccentric distance on the vibration responses of critical locomotive components are revealed. These findings provide valuable theoretical guidance for the operational maintenance and fault diagnosis of traction motors in direct-drive locomotives.

A Disturbance Compensation Control Strategy for Rotational Speed Standard Device Based on AMB System.

The rotational speed standard device that can carry loads is the key device for calibrating passive rotational speed sensors. The rotor of the passive rotational speed sensor is connected to the rotor of the standard speed device through a coupling, and the standard reference speed is provided by the standard device. Due to the rotor eccentricity, the unbalanced force of the rotor occurs, and it can not only affect the rotational speed accuracy but can also damage the mechanical bearings of the standard speed device. To solve this issue, a method for suppressing the unbalanced force of the speed standard device based on an active magnetic bearing (AMB) force compensation system is proposed. First, the overall structure of the system is briefly introduced. Then, the force feedback control system model with the AMB as the force actuator is established, and a PI controller is designed to achieve the disturbed force control. Finally, a semi-physical simulation experimental platform is built to verify the effectiveness of the proposed method. The experimental results show that the AMB force compensation system can reduce 84.4%, 81.6%, and 79.8% of the unbalanced vibration force at the frequency of 30 Hz, 90 Hz, and 150 Hz, respectively.

Kinematics-Based Design Method and Experimental Validation of Internal Meshing Screw for High-Viscosity Fluid Mixing

The challenge of mixing high-viscosity materials is a common issue encountered in the manufacturing process of food materials. The advantages of the internal meshing screw mixer have led to its adoption in various manufacturing processes, but it has yet to be implemented in the food industry. The paper presents a design method for an internal meshing screw mixer based on kinematic principles. The mixer features a helical chamber created by alternating volumes formed by the stator and rotor, establishing an extension-dominated environment for mixing high-viscosity fluids. A kinematic model based on the internal cycloid principle was established, providing trajectories and equations for key points on the rotor, simulating both its rotation and revolution processes, and revealing the velocity variations at different points on the rotor. Based on the kinematic analysis results, a stator and rotor design method was developed according to relevant functional divisions. To achieve the desired motion effects, transmission and support devices were designed, and the relationship between the transmission device and the internal cycloid surface of the fixed rotor was established. The mixer’s application and mixing effectiveness in the food industry were validated using corn syrup and flour. Experimental results showed that the extensional mixer described in the paper effectively mixed high-viscosity fluids while also efficiently blending fine powders. Slurry viscosity was tested with a rheometer at different speeds with an eccentric rotor mixer. Results showed that viscosity decreased with increasing shear rate, with a more pronounced decrease at higher shear rates. The apparent viscosity trend remained consistent at different speeds, although variations were observed at lower shear rates, especially concerning speed. The non-Newtonian fluid index exhibited minimal variations at different speeds, while the consistency coefficient showed significant fluctuations. The mixing uniformity index of the slurry was used to evaluate the mixing uniformity and dispersion uniformity of this extensional mixer. At different rotational speeds, the density of the slurry changes little. The uniformity index of mixing decreases gradually with the increase of rotational speed, reaching its maximum at 15 r/min. The overall trend of the uniformity index decreases with increasing rotational speed, indicating a decrease in density uniformity. A peak appears at 45 r/min, possibly due to the maximum values of elongation rate and shear rate at this speed. As the rotational speed increases, the residence time of the material in the mixer decreases, which may be the main reason for the decrease in mixing uniformity. These findings provide valuable insights into the design and utilization of extension-dominated screw mixers within the food industry, laying a solid foundation for future research and practical applications in this field.

Diagnostics of Interior PM Machine Rotor Faults Based on EMF Harmonics

This article presents a detailed study on the diagnosis of rotor faults in an Interior Permanent Magnet Machine based on a mathematical model. The authors provided a wide literature review, mentioning the fault diagnosis methods used for Permanent Magnet Machines. The research emphasizes the necessity of precise assumptions regarding winding construction to accurately analyze the additional harmonics appearing in rotor faults caused by electromotive force (EMF), i.e., rotor eccentricity and magnet damage. The article also discusses specific features appearing in the spectrum of air gap permeance functions and the impact of rotor eccentricity and magnet damage on PM flux density distribution and as a consequence on EMF stator windings. The novelty of the presented content is the analysis of induced EMFs for cases of the simultaneous occurrence of rotor eccentricity and PM damage. The findings of this study provide valuable insights for the diagnosis and understanding of internal asymmetries in Interior PM Machines.

Influence of Slot and Pole Number Combinations on Cogging Torque in PM Machines With Interaction of Tooth Bulge and Rotor Eccentricity

Influence of Slot and Pole Number Combinations on Cogging Torque in PM Machines With Interaction of Tooth Bulge and Rotor Eccentricity

Investigation of electromagnetic processes in the case of static eccentricity of a two-pole induction motor with a short-circuited rotor

Purpose. Correction of the mathematical model of electromagnetic processes in a two-pole induction motor with a short-circuited rotor, taking into account static rotor eccentricity to identify diagnostic correlations. Methodology. Analytical modeling using the method of specific magnetic conductivity, mathematical modeling of electromagnetic fields in a three-phase induction motor with a short-circuited rotor using methods of electromagnetic field theory and finite element methods. Obtained results. The necessity of improving mathematical models for induction motors with short-circuited rotors to establish new or refine connections between diagnostic features and diagnosed defects has been demonstrated. Refined mathematical expressions for calculating the specific conductivity of non-uniform air gaps in induction motors with static eccentricity are provided. Modeling was performed using the FEMM environment for a statically eccentric two-pole induction motor with a short-circuited rotor. It has been proven that the harmonic order values obtained using the numerical-field method are consistent with those obtained analytically. Findings. Based on the field approach and using the finite elements method, an analysis of the distribution of magnetic field in a two-pole induction motor with a short-circuited rotor was conducted. Harmonic analysis of the magnetic field in the air gap was performed to identify the fundamental harmonic and higher and lower-order harmonics when eccentricity occurs. The influence of static rotor eccentricity on the electromagnetic processes of the induction motor was analyzed. Practical value. The results of the study can be utilized for functional diagnosis of the rotor winding of induction motors based on the radial component of the magnetic field. This will contribute to enhancing the reliability of induction motors and enable the prevention of failure in induction motors with short-circuited rotors.

A novel rotor internal bend actuator for the wireless compensation of inherent eccentricities

A novel internal rotor bend actuator is presented that enables compensating strains to be applied about the rotor centre. Axial reaction tubes are used to maintain the structural stability of the bend actuator and to provide feedback on the level of actuation. The system is powered by an onboard battery and the actuation is derived from the operation of lead screw motors. The actuation is commanded wirelessly, thus providing the functionality for an autonomous rotor. The integrated rotor is demonstrated in isolation via laser tracker measurements and for the rotating prototype system. Actuated bending gave rise to radial displacements at the central point relative to shaft ends of approximately 50µm peak-to-peak. These results validate a finite element deformation model. The rotor was levitated on active magnetic bearings, then rolling elements bearings, to demonstrate the synchronous vibration control achievable by static internal bending. The potential now exists for the commanded actuation to compensate for rotor eccentricities arising from manufacturing errors and dynamically induced unbalance for the cancellation of underlying synchronous vibration.

A piezoelectric-electromagnetic hybrid energy harvester with frequency-up conversion mechanism towards low-frequency-low-intensity applications

This paper proposes a piezoelectric-electromagnetic hybrid energy harvester (PEHEH) with frequency-up conversion (FUC) mechanisms toward harvesting low-frequency-low-intensity, and wideband vibrational energy. The PEHEH consists of a stator with embedded coils, an eccentric rotor embedded with permanent magnets, and a fan-folded piezoelectric beam fixed to the stator. The eccentric rotor converts low-frequency straight vibration into rotational motion, and generates currents across the coils. The rotor could collide with the fan-folded beam, resulting in voltage generation due to the deformation of the fan-folded beam. The FUC mechanism broadens the bandwidth and harvests additional energy through the piezoelectric effect. The fan-folded beam can be considered as a nonlinear oscillator of hardening type. The electro-magnetic-mechanical system is modeled as a driven pendulum that impacts a mass-spring-damper system. The electromagnetic coupling effect is theoretically determined and equivalent to a nonlinear damping term. The nonlinear dynamical system is analyzed theoretically, numerically and experimentally. The results show that the bandwidth of the PEHEH is broadened than that of the energy harvester without the FUC mechanism. The maximum power reaches 26.4 mW at 4 Hz. The PEHEH can power an acceleration sensor at 4 Hz in laboratory environments and a temperature-humidity sensor in actual working conditions of an agricultural tractor's spray rod.

Mixed Eccentricity Fault Detection for Induction Motors Based on Time Synchronous Averaging of Vibration Signals

This paper presents a method based on vibration signals to diagnose rotor mixed eccentricity faults in three-phase squirrel cage induction motors (SCIMs). Rotor eccentricity is a typical fault in SCIMs that significantly affects the performance of electrical machines and results in unwanted vibrations. The time synchronous averaging (TSA) signal, which consists of the harmonics components generated by the fault, is obtained via the characteristic frequency of the eccentricity fault. TSA is decomposed into two signals: TSA-regular and TSA-difference, which are respectively similar to approximate and details of wavelet transform. Based on the fault index, which is the maximum FFT value of the TSA-difference signal, the healthy and faulty motors can be distinguished. The proposed approach is evaluated on an experimental test rig equipped with a 1.5 kW SCIM supplied directly from the power grid under various load conditions. The results illustrate the effectiveness of the proposed approach in detecting the rotor mixed eccentricity faults.