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Introduction: Conventional sensor-based fault detection techniques lead to huge manpower, high cost and requires a greater number of sensors. To overcome these flaws, current signature-based fault estimation is proposed. This method does not require any additional current sensors and is done with existed sensors employed for motor speed control. Further, the stator current is divided into two phase currents using Parks vector approach to get better resolution. The higher order noise due to data acquisition, EMI and other sources is removed using wavelet de-noising and the resolution on current spectrum is improved using advanced spectral analysis namely Stockwell Transform (ST). All the faults faced by induction motor like bearing damage, broken rotor, and stator inter turn faults are tested at different load conditions. The severity of the fault is identified using feature parameters like RMS and Standard Deviation of stator current after proposed signal processing. A 1.5 KW, 440 V and 50 Hz induction motor is used for expermental verification of proposed fault assessment criteria. Purpose: The present work attempts a novel approch to estimate incipient faults in Induction motor using motor current signature analysis (MCSA). Methods: Advanced spectral analysis namely Stockwell Transform (ST) along with Park's vector approch technique has been adopted to diagnosis the various faults in induction motor (IM) using MCSA. Result and Conclusions: The proposed fault indexing parameters (FIP) with selected features like RMS and SD is successful in estimating the fault severity and its behaviour. Various faults at different load conditions are tested and concluded that, 3-hole rotor fault, 3-hole inner race fault and combined fault have high impact over other faults. [ABSTRACT FROM AUTHOR]

As regards bearing fault detection of induction motors using stator current, anything unrelated to the faults is the "noise". The noise attenuation leads to an improved estimation of the bearing fault signal. The gist of this study is the integration and synchronization of the three residues obtained from the current noise cancelation methods: Time Shifting and Linear Prediction. This procedure results in a richer bearing fault signal than any of the individual residues through cross-correlation. The developed method efficiently synchronizes and integrates the current residues so that fault characteristic frequencies can be more conspicuous in spectral analysis. Both simulation and experimental results attest to the merit and effectiveness of the developed method in detecting both outer and inner race bearing faults. [ABSTRACT FROM AUTHOR]

Protocols are proposed for controlled remote implementation of operations here. Sharing a (2N+1)$(2N+1)$‐partite graph state, 2N participants collaborate to prepare the stator and realize the operation ⊗j=1Nexp[iαjσnOj]$\otimes _{j=1}^N\exp {[i\alpha _j\sigma _{n_{O_j}}]}$ on N unknown states for distributed systems Oj$O_j$, only with the permission of a controller. The control power analysis shows that without the controller's permission, eight specified operations can be implemented with the success rate of 50%, other operations can be realized with the success rate of 25%, and thus the control power is reliable. All the implementation requirements of this protocol can be satisfied by means of local operations and classical communications, and the experimental feasibility is presented according to current techniques. The entanglement requirement of this protocol is characterized in terms of geometric measure of entanglement. It turns out to be economic to realize the control function from the perspective of entanglement cost. [ABSTRACT FROM AUTHOR]

This paper presents a designed experimental simulation scheme for dynamic air gap eccentricity (DAGE) faults in permanent magnet synchronous generator (PMSG), along with the testing of their electromechanical characteristics. Unlike previous studies, this paper proposes and applies an experimental device setting scheme that enables accurate and convenient calibration of the DAGE fault degree, offering a novel solution for practical DAGE simulation. The experimental unit measures the electromechanical characteristics of the PMSG before and after the DAGE fault, taking into account the influence of load. The mechanical parameter considered is the stator vibration, while the electrical parameter is the circulating current parallel branches (CCPB) inside the stator winding. The characteristic frequencies of stator vibration and CCPB under the DAGE fault are analyzed based on the experimental results and verified through theoretical calculations and finite element analysis (FEA). The findings demonstrate the effectiveness of the proposed DAGE experimental device. Moreover, DAGE failure increases the strength of stator vibration and introduces new frequency components, namely fr and 2f ± fr. Under normal operation, the PMSG exhibits no CCPB. However, DAGE faults cause CCPB with frequency components of f ± fr. Moreover, the severity of the fault degree positively correlates with larger root‐mean‐square (RMS) values and characteristic frequency amplitudes of stator vibration and CCPB. Furthermore, the amplitude of stator vibration and CCPB decreases with increasing load. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The influence of the hull-modulated inflow on the propulsion performance of the propeller is related to the matching design of the propeller–hull system. In the present study, considering the working conditions of the pump-jet propulsor in uniform inflow and two types of hull-modulated inflow, based on improved delay detached eddy simulation, the influence of hull-modulated inflow on unsteady force fluctuations and vortex dynamics of pump-jet propulsor under design conditions is carried out. The results show that the hull-modulated inflow increases the propulsion efficiency of the pump-jet propulsor to varying degrees within the range of the calculated advance coefficient and has a significant influence on the frequency characteristics of the unsteady force spectra characteristics of each component of the pump-jet propulsor. It also shows changes in the magnitude characteristics, that is, the energy transfer process of an individual rotor blade from the stator blade passing frequency to other harmonics of the shaft rotation frequency, and the thrust spectrum of an individual stator blade presents broad-spectrum characteristics in the high-frequency range. Furthermore, the application of hull-modulated inflow directly affects the shape of the stator shedding vortex, causing some of the stator blade shedding vortices to separate early and aggravating its short-wave instability. More secondary vortices are induced to accelerate the instability of the rotor blade tip clearance vortex. The energy transfer mechanism from the rotor blade passing frequency and its harmonics to the broadband spectra appears in the wake field of the pump-jet propulsor. [ABSTRACT FROM AUTHOR]

In this paper, the performance of different continuous-time and discrete-time models of the electrical subsystem of induction machines and permanent-magnet synchronous machines as well as methods based on them for decoupling the direct and quadrature axis components of the stator current are investigated and compared. The focus here is on inverter-fed, pulse width modulated drives when operated with a relatively large product of stator frequency and sampling time, where significant differences between the models and decoupling methods used come to light. Recommendations for a discrete-time model to be used uniformly in the future are made, as well as statements on whether feedforward or feedback decoupling structures are better suited and whether state controllers improve decoupling measures for very steep speed ramps. Simulation studies and measurement results support the statements made above. [ABSTRACT FROM AUTHOR]

In this article, a stator flux oriented sensorless control method is proposed for interior permanent magnet synchronous motor (IPMSM) drives based on the direct torque and flux control (DTFC) and pseudo-random high-frequency signal injection (PR-HFSI) in the zero-low speed range. The DTFC for IPMSMs is introduced briefly and the conventional high-frequency signal injection (HFSI) method, which requires an additional transformation, is also introduced. Then the stator flux oriented PR-HFSI is proposed comprising injection mode and rotor observation, with the aim of noise reduction and easy implementation. Furthermore, the high-frequency noise in HFSI and the mechanisms of noise suppression in PR-HFSI are analyzed based on current spectrums. Meanwhile, the optimal noise reduction frequency combination of n kinds frequency injections is also analyzed. Finally, the performance of the proposed stator flux oriented PR-HFSI method is confirmed with experiments on a 60 kW IPMSM test bench. [ABSTRACT FROM AUTHOR]

This paper presents an improved cascaded model-free predictive speed and current control with the periodic and aperiodic disturbances suppression to achieve a smooth speed. The cascaded structure has an external speed loop and an internal current loop, both implemented with model-free predictive control to enhance the robustness of the controller. The current loop is designed based on the finite control set model-free predictive current control (FCS-MFPCC) strategy with an ultra-local model to regulate the stator currents, and the speed loop uses the proposed continuous control set model-free predictive speed control (CCS-MFPSC) to make full use of the excellent dynamic performance of the current-loop controller. To suppress the periodic disturbance that exists in the PMSM system, an improved parallel quasi-resonant controller (QRC) with an error limitation is embedded into the CCS-MFPSC, which can generate the compensated current. Based on the stability condition, the stability of the proposed MFPSC-QRC strategy is directly analyzed in the z-domain. Finally, the effectiveness and feasibility of the proposed cascaded model-free predictive speed and current strategy are validated on a PMSM test platform. • This paper proposes a cascaded strategy for PMSM drives by combining CCS-MFPSC and FCS-MFPCC. • The CCS-MFPSC is designed for the speed loop to enhance the dynamic performance • An improved QRC is studied to suppress the aperiodic and periodic disturbances simultaneously. • The stability is directly analyzed in the z-domain. [ABSTRACT FROM AUTHOR]

This research examines how fluid damping loss affects the operation of a two-pole, 5.5 HP (4 kW) induction machine (IM) within the context of different slot opening configurations developed for downhole water pump applications. Since these motors operate with their cavities filled with fluid, the variations in fluid viscosity and density, compared to air, result in the occurrence of damping losses. Furthermore, this loss can be attributed to the motor's stator and rotor surface geometry, as the liquid within the motor cavity moves unrestrictedly within the motor housing. This study involves the examination of the damping loss in a 24-slot IM under different stator slot indentations. The investigation utilizes computational fluid dynamics (CFD) finite element analysis (FEA) and is subsequently validated through experiments. The aim of this work is to emphasize the significance of fluid damping loss in submerged machines. Results reveal that the damping loss exceeds 8% of the motor output power when the stator surface has indentations, and it diminishes to 3.2% of the output power when a custom wedge structure is employed to eliminate these surface indentations. [ABSTRACT FROM AUTHOR]

A significant electromotive force is induced in the rotor circuit of a doubly fed induction generator (DFIG) due to its high vulnerability to grid faults. Therefore, the system performance must be increased with appropriate control actions that can successfully offset such abnormalities in order to provide consistent and stable operations during grid disturbances. In this regard, this paper presents a solution based on a combination of an energy storage-based crowbar and a rotor-side crowbar that makes the effective transient current and voltage suppression for wind-driven DFIG possible. The core of the solution is its ability to restrict the transient rotor and stator overcurrents and DC-link overvoltages within their prescribed limits, thereby protecting the DFIG and power converters and improving the system's ability to ride through faults. Further, the capacity of an energy storage device for transient suppression is estimated. The results confirmed that the proposed approach not only kept the transient rotor and stator currents within ±50% of their respective rated values in severe system faults but also limited the DC-link voltage variations under ±15% of its rated value, achieving transient control objectives precisely and maintaining a stable grid connection during the faults. [ABSTRACT FROM AUTHOR]

The paper presents selected results of comparative analysis of prototype synchronous motors with permanent magnets intended for multichannel power supply. This types of motors are used where high reliability and safety are required - the so-called critical drives. Two designs with different method of making the stator winding were analyzed. The first prototype had a winding with a full pitch, while the second one had a winding with a fractional pitch. Both constructions with the same rotor (surface mounted magnets - SPM) allow to introduce some internal asymmetry (electrical and magnetic) in one of the motor channel. The tests included a few options of power supply - respectively: one, two and four channels in the conditions of symmetry and internal asymmetry simulated in channel A. Selected waveforms of currents and voltages have been shown. The mechanical characteristics of both motors were compared, taking into account multi-channel operation and selected cases of internal asymmetry. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics 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 Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control 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.)

ABSTRACTSwarming is a macroscopic phenomenon in which surface bacteria organize into a motile population. The flagellar motor that drives swarming in Pseudomonas aeruginosa is powered by stators MotAB and MotCD. Deletion of the MotCD stator eliminates swarming, whereas deletion of the MotAB stator enhances swarming. Interestingly, we measured a strongly asymmetric stator availability in the wild-type (WT) strain, with MotAB stators produced at an approximately 40-fold higher level than MotCD stators. However, utilization of MotCD stators in free swimming cells requires higher liquid viscosities, while MotAB stators are readily utilized at low viscosities. Importantly, we find that cells with MotCD stators are ~10× more likely to have an active motor compared to cells uses the MotAB stators. The spectrum of motility intermittency can either cooperatively shut down or promote flagellum motility in WT populations. In P. aeruginosa, transition from a static solid-like biofilm to a dynamic liquid-like swarm is not achieved at a single critical value of flagellum torque or stator fraction but is collectively controlled by diverse combinations of flagellum activities and motor intermittencies via dynamic stator utilization. Experimental and computational results indicate that the initiation or arrest of flagellum-driven swarming motility does not occur from individual fitness or motility performance but rather related to concepts from the “jamming transition” in active granular matter.IMPORTANCEIt is now known that there exist multifactorial influences on swarming motility for P. aeruginosa, but it is not clear precisely why stator selection in the flagellum motor is so important. We show differential production and utilization of the stators. Moreover, we find the unanticipated result that the two motor configurations have significantly different motor intermittencies: the fraction of flagellum-active cells in a population on average with MotCD is active ~10× more often than with MotAB. What emerges from this complex landscape of stator utilization and resultant motor output is an intrinsically heterogeneous population of motile cells. We show how consequences of stator recruitment led to swarming motility and how the stators potentially relate to surface sensing circuitry.

This study develops a ferrofluid-lubricated thrust bearing with an air cushion. The bearing comprises a rotor, a stator, and a ferrofluid ring formed between them due to absorption by an annular magnet under the stator. The design makes it possible for the air cushion (air sealed inside the ferrofluid ring) as well as the magnetized ferrofluid to supply supporting forces. A model of the bearing for a static supporting force is proposed and validated by experiments. As the gap between the rotor and stator was 0.25 mm, the maximum static supporting force of the bearing was 3.2 N, much higher than the support provided by the pure ferrofluid ring (without the air cushion, 1.7 N). The operating space of the bearing was detected by multicycle load–retract tests with remarkably high and repeatable accuracy. The results of dynamic experiments show that the speed of rotation of the rotor has a minor effect on the supporting force. Such a ferrofluid-lubricated bearing offers promise for use in precise positioning or low-friction systems. [ABSTRACT FROM AUTHOR]

The high resistance connection fault of the stator is a common fault in doubly fed induction generators, which causes a three-phase imbalance in the stator circuit. Since the stator winding is directly connected to the power grid, interference from the asymmetric power grid must be eliminated in order to achieve the accurate diagnosis of stator resistance imbalance faults. Therefore, a new diagnosis method based on filter shunt capacitor banks is proposed in this paper. By introducing shunt capacitor banks, an artificial neutral point is constructed to replace the neutral point of the power grid. Then, the neutral point voltage of the stator winding relative to the artificial neutral point is selected as a fault characteristic signal. In this paper, the change in three-phase stator currents after a high-resistance connection fault is analyzed in detail, and by comparing the fault characteristic signal with three-phase stator currents, the fault phase location and fault severity of high-resistance connection can be accurately obtained. Finally, simulations are carried out via the field-circuit coupling method to validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

With the growing utilization of disc motors, the enhancement of their operational stability has become a critical research area. The existing studies usually focus on improving the pole structure of the rotor or the stator structure to optimize one performance of the motor and less on optimizing multiple performances. This paper simultaneously improves the rotor pole structure and stator tooth structure of the motor in order to optimize the sinusoidal waveform of the no-load back electromotive force and the cogging torque at the same time to achieve the goal of reducing the vibration and noise of the permanent-magnet synchronous dual-rotor statorless magnetically coupled disc motor and improve its operational stability. A finite element simulation model of a 20-pole, 24-slot permanent-magnet synchronous dual-rotor statorless magnetically coupled disc motor is established to analyze the influence of various factors, including the number of magnetic pole steps, the opening position, depth, and width of the stator auxiliary slot, on the motor performance. The results show that this stator–rotor combination improvement method effectively reduces the total harmonic distortion (THD) and attenuates multiple harmonics, and the peak cogging torque pulsation is significantly improved while other properties of the motor meet the technical requirements, and the motor performance is improved. [ABSTRACT FROM AUTHOR]

The series-winding permanent-magnet synchronous motor (SW-PMSM) has the merits of high output power and excellent control performance, as does the open-winding permanent-magnet synchronous motor (OW-PMSM). Meanwhile, it can greatly reduce the number of power devices. However, due to the existence of the zero-sequence path, zero-sequence current occurs, which can cause additional losses and torque ripples. Thus, this paper proposes a novel direct torque-control strategy for the SW-PMSM with zero-sequence current suppression capability (ZSCS-DTC). First, the series-winding topology (SWT) and the voltage vector distribution in the SW-PMSM drives are analyzed. Secondly, the basic DTC (B-DTC) scheme for the SW-PMSM is investigated, and the defects of zero-sequence current open-loop control in the B-DTC scheme are revealed. Thirdly, a new voltage vector synthesis scheme is proposed for suppression of zero-sequence current while ensuring bus voltage utilization. A switching table is reconstructed with the newly synthesized voltage vectors. On this basis, a ZSCS-DTC scheme for the SW-PMSM is proposed based on zero-sequence current closed-loop control so that electromagnetic torque, stator flux linkage and zero-sequence current can be controlled simultaneously. Finally, the effectiveness of the proposed ZSCS-DTC scheme for the SW-PMSM drives is verified. [ABSTRACT FROM AUTHOR]

A high temperature superconducting (HTS) dynamo is a type of device known as a "flux pump" that can inject DC into a closed superconducting circuit. Here, we report experimental results from a variable-temperature dynamo-type HTS flux pump operated within a cryo-cooled chamber. This device employs a "continuous stator" topology, whereby an HTS "coated conductor" is wrapped to form a cylinder around a mechanical rotor such that applied flux from the rotor magnet must always penetrate the stator. This leads to a high current device that can inject >1 kA into a series-connected HTS coil at 53 K. The open-circuit DC output voltage (Voc) from this HTS dynamo has been studied at stator temperatures between 35 and 95 K and attained a maxima at a temperature ∼5 K lower than the stator Tc. At lower temperatures, Voc decreases and falls to zero below ∼40 K. This non-intuitive effect is found to be due to flux-screening by critical currents flowing with the HTS stator, which increase with decreasing temperature. These shielding currents prevent flux from penetrating the HTS stator and, hence, reduce the magnitude of locally induced emf (and thus DC output) within the HTS film. A key implication of these results is that all magnetically driven HTS flux pumps should be operated at temperatures well above their flux-screening point, and this consideration must be taken into account for future designs of multi-kA class HTS flux pumps. [ABSTRACT FROM AUTHOR]

Magnetic‐geared double‐rotor machines are recognized as a promising power‐splitting component in hybrid electric aircrafts (HEAs). However, the high fuel efficiency speed of the turbine engine in HEAs is about 10,000 rpm, whereas conventional topologies suffer from low efficiency at high speed due to its specific operation principle—the magnetic field modulating principle. A coreless stator magnetic‐geared double‐rotor machine (CS‐MGDRM) is proposed to enhance high‐speed efficiency and thus comply with the operation condition of HEAs. First, the machine structure and hybrid propulsion system configuration are introduced, and power‐flow analysis of three basic operation modes is presented. Second, the operation principle of the machine is illustrated, and investigation of electromagnetic performances is carried out by finite element analysis. Third, an analytical model of the machine is developed, based on which the design optimization towards the maximum torque capacity is investigated. Furthermore, the loss distribution law and transmission efficiency are analysed and compared with conventional scheme, and the power factor characteristic is investigated as well. Finally, the overall performance of the proposed machine is evaluated. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

FliL is an essential component of the flagellar machinery in some bacteria, but a conditional one in others. The conditional role is for optimal swarming in some bacteria. During swarming, physical forces associated with movement on a surface are expected to exert a higher load on the flagellum, requiring more motor torque to move. FliL was reported to enhance motor output in several bacteria and observed to assemble as a ring around ion‐conducting stators that power the motor. In this study we identify a common new function for FliL in diverse bacteria—Escherichia coli, Bacillus subtilis, and Proteus mirabilis. During swarming, all these bacteria show increased cell speed and a skewed motor bias that suppresses cell tumbling. We demonstrate that these altered motor parameters, or "motor remodeling," require FliL. Both swarming and motor remodeling can be restored in an E. coli fliL mutant by complementation with fliL genes from P. mirabilis and B. subtilis, showing conservation of a swarming‐associated FliL function across phyla. In addition, we demonstrate that the strong interaction we reported earlier between FliL and the flagellar MS‐ring protein FliF is confined to the RBM‐3 domain of FliF that links the periplasmic rod to the cytoplasmic C‐ring. This interaction may explain several phenotypes associated with the absence of FliL. [ABSTRACT FROM AUTHOR]

A comparative study on the wake dynamics of a pump-jet propulsor (PJP) and a ducted propeller (DP) is conducted to investigate the effects of the pre-swirl stator and corresponding stator–rotor interaction on the wake evolution and destabilization mechanisms of a PJP system. The flow field analysis, vortex structure identification, and dynamic mode decomposition (DMD) analysis are carried out based on the numerical results obtained from delayed detached eddy simulations. The numerical hydrodynamic loading and flow field of the PJP are compared with experimental results, and they are in good agreement. Compared with the DP, the stator trailing vortices of the PJP interact with the rotor trailing vortices as well as the hub vortex, accelerating their diffusion and viscous dissipation. The pre-swirl stator triggers the generation of secondary vortices and moderates the spiral behavior of tip leakage vortices, which dominates the wake instability of PJP. The DMD analysis revealed that the wake field evolution is primarily characterized by the different mode structures at blade passing frequency and its multiples, especially in the PJP due to its strong stator–rotor interaction. The modal energy decays faster in the PJP wake field owing to its more turbulent and earlier instability. The hub vortex plays an important role in the wake dynamics of the DP. [ABSTRACT FROM AUTHOR]

The endwall flow significantly impacts the turbine performance behavior, and it is necessary to investigate the development of endwall secondary vortices and relevant losses. Inspired by the field synergy principle, the synergy between the velocity and the pressure gradient established by the three-dimensional mechanical energy conservation equation is innovatively applied to the endwall loss analysis in the stator of an axial-inflow turbine. In terms of the synergy equation, the loss is not only related to the viscous dissipation, but also the included angle (or the synergy angle) between the velocity vector and the pressure gradient vector. The physical content of the synergy angle suggests that the larger synergy angle is (i.e., the worse synergy), the higher losses should be. This conclusion has been validated by present numerical results, and an apparent positive correlation between the synergy angle and the losses could be perceived under time-averaged and transient conditions. The worse synergy could be observed at the passage rear part and the wake, where complex passage vortices and local separation exist. In these regions, the local velocity vector is not aligned with the bulk pressure gradient of the mainstream. Hence, the synergy angle has a marked rise, corresponding to the local high losses. [ABSTRACT FROM AUTHOR]

In this paper, an enhanced control scheme for doubly fed induction generators (DFIGs) operating in the standalone mode is proposed and experimentally validated. The intended aim is to regulate the amplitude and frequency of DFIG stator voltage profile, subjected to variations in the electrical load and rotor speed. For that, the excitation of DFIG is manipulated via rotor side converter (RSC), typically known as field-oriented control strategy fed by a hysteresis current controller. To reach the projected aim, a fuzzy logic controller (FLC) is implemented and systematically investigated. Compared to its counterpart Mamdani type, the fuzzy inference system (FIS) is based on Takagi–Sugeno (T–S) method, which is justified by comparatively lower computational burden and enhanced practical implementation. The advantages of the proposed T–S based FLC are highlighted by conducting a comprehensive comparison with the conventional PI controller and Mamdani type FLC. Both the simulations study and experimental verification are conducted under diverse scenarios: (i) a wide range of rotor speed, (ii) sudden variations in the electrical load, and (iii) step changes in the desired stator voltage profile. The simulation study and experimental analysis are, respectively, conducted via MATLAB/Simulink platform and dSPACE DS1104 platform. The results depict superior performance of proposed T–S type FLC scheme, when compared with the conventional PI controller. Moreover, based on experimental findings, the proposed scheme leverages 0.26 ms reduction in the computational time (vs Mamdani FLC), facilitating a superior practical implementation. [ABSTRACT FROM AUTHOR]

Stator turn-to-turn faults occur due to improper loading, eccentricity in the rotor, and increases in the operating temperature. During the occurrence of a stator turn-to-turn fault, an abnormal temperature increase occurs, and if this state is left unattended for a long duration, it can lead to degradation of the permanent magnet. This paper presents an analytical modeling scheme for surface permanent magnet brushless DC motors for diagnosing and classifying stator turn-to-turn faults using SIMULINK® during non-stationary operating conditions. A significant increase in the stator current, back EMF, torque, and speed is observed. A current signature analysis is performed during non-stationary operating conditions using a fast Fourier transform method to identify the severity of the fault. Furthermore, a simple and efficient classification model is developed by selecting the best classifier among the decision trees, neural network, support vector machine, discriminant analysis, and ensemble classifier. A statistical evaluation of the current signal for fault feature extraction and ranking is performed based on minimum redundancy and maximum relevance, Chi-square test, Relief F, analysis of variance, and Kruskal–Wallis test. The dataset for classification is extracted from a Simulink analytical model. Neural network-based classifiers can classify faults precisely and rapidly with a minimum number of features. [ABSTRACT FROM AUTHOR]

This paper presents the performance analysis of a three-phase squirrel cage induction motor (SCIM) with a double–triple-layer (DTL) stator winding configuration operating with broken rotor bar (BRB) faults. The effects of BRB faults on the performance of specific parameters are analyzed under a steady-state regime. The SCIM is modeled using the two-dimensional finite element method (FEM) to study electromagnetic performance under healthy and BRB faulty conditions. To validate the finite element analysis (FEA) results, a prototype of an SCIM with a DTL stator winding configuration is tested for performance evaluation under healthy and BRB faulty conditions. The FEA and experimental (EXP) results of the SCIM with a DTL stator winding arrangement are compared with the results of the SCIM with a conventional double-layer (CDL) stator winding configuration. FEA and EXP results evidenced that the SCIM with a DTL stator winding configuration mitigates some of the adverse effects introduced by the BRB faults compared to the SCIM with a CDL stator winding of the exact specifications. Under loaded conditions, the SCIM with a DTL stator winding configuration reduced the magnitudes of the twice slip frequency sidebands caused by BRB faults from ±1.2 Hz for the SCIM with a CDL stator winding arrangement down to ±0.2 Hz and ±0.36 Hz when operating with 3BRB and 6BRB faults, respectively. The results also indicate that the SCIM with a DTL stator winding configuration has reduced the decibel sideband magnitude by 7.5 dB and 8 dB for unloaded and loaded conditions, respectively. This premise has positioned the SCIM with a DTL stator winding configuration as a strong candidate in applications where BRB faults are frequent, and the motor may be required to continue operating with a BRB fault until scheduled maintenance is in effect. [ABSTRACT FROM AUTHOR]

In this study, the focus is on the magnetic path formation and its effects on the performance of a counter-rotating dual-rotor permanent-magnet flux-switching machine (CR-DRPMFSM) for direct-drive counter-rotating wind power generation, based on different stator slot and rotor pole combinations. To fully exploit rotor-shaft bore and improve fault-tolerant design, as well as increase torque density, dual-rotor topologies with the capability for dual electrical and dual mechanical ports are investigated. Moreover, the direct-drive counter-rotating wind power generation technique offers a brushless topology, thus reducing maintenance cost and improving energy conversion efficiency compared to single-blade wind turbine systems. Using finite element analysis (FEA), the inherent magnetic coupling of the series and parallel paths shows varied impacts on the electromagnetic performance of four different CR-DRPMFSMs based on the slot/pole combinations (MI to MIV) considered in this study. The key electromagnetic performance indices, such as torque, cogging torque, torque ripple, power factor, and efficiency, show proportionate variation to the coupling level. A comparative analysis shows that MI exhibits higher average torque, lower torque ripples, and high efficiency, reaching 90% with a power factor of 0.6. As an optimal design, an MI test prototype is developed. The experimental test prototype validates the FEA results under no-load and on-load conditions. [ABSTRACT FROM AUTHOR]

Introduction. The best way to control the torque of an induction motor is conventional direct torque control (DTC); this control method is the most used approach in the industrial sector due to its many advantages. Its main advantages are its simplicity and its exclusive dependence on the stator resistance of the induction motor. However, the use of hysteresis comparators reduces its effectiveness, causing more torque ripple. Additionally, this results in variable operating frequency and limited frequency sampling, resulting in pseudo-random overshoot of the hysteresis band. Purpose. For these reasons, this article presents a new study aimed at confirming its shortcomings and improving the effectiveness of the control. Novelty. We propose to use fuzzy logic methods to estimate the two components of the stator flux. Methods. In traditional DTC the flux components are estimated from an equation relating the stator resistance to the stator voltage and current. In the proposed method, only stator currents and voltages are used for this evaluation, which eliminates the dependence of DTC on stator resistance. The aim of this proposal is to make DTC robust to parametric changes. Results. General harmonic distortions, rotational speed of the induction motor, electromagnetic moment, magnetic flux and stator currents are analyzed. Practical value. With this proposed technique, validated in Simulink/MATLAB, several improvements in motor behavior and control are endorsed: torque fluctuations are reduced, overshoot is completely eliminated, and total harmonic distortion is significantly reduced by 48.31 % for stator currents. This study also confirmed the robustness of DTC to changes in stator resistance. [ABSTRACT FROM AUTHOR]

Introduction. The drive electric motor is one of the key components in the traction chain of an electric vehicle. Traditional radial flux motors used in electric vehicles, which use permanent magnets or induction motors in an electric field, are experiencing significant development aimed at optimizing their weight and cost. However, it can only go so far, so switching to a completely different type of machine, such as an axial flow, might be a good alternative. The novelty to this item is an axial flux permanent magnet motorization with non-slotted TORUS-NS rotor (single interior stator with two external rotors North-South) type housed in the wheel of the vehicle; this allows power to pass directly from the motor to the wheel, increasing the efficiency of the motor. System complexity is also less, as the transmission, differentials and driveshaft are eliminated. Purpose is to equip the electric car and choose the motor adapted to the application and the available space. The smaller size and weight allows for a lighter vehicle and more batteries, thus increasing range. The focus on customization is because vehicle performance is so dependent on the quality of the vehicle architecture, battery pack and axial flux motor design. The results obtained are in good agreement of accuracy, in particular the flux density at the air gap. The investigation is carried out by the finite element method. Machine model was run on Maxwell 16.0 business code. [ABSTRACT FROM AUTHOR]

The doubly fed induction generator (DFIG) is particularly sensitive to grid faults, representing a significant drawback of this generator type, because of the direct connection of its stator windings to the network. The electromagnetic coupling between the stator and rotor in the DFIG results in an undesirable consequence, where voltage dips lead to excessive stator current, causing high currents in sensitive inverters and overloading the DC-link condenser. This document outlines a comparative study that examines two protection scheme configurations with a proportional-integral (PI) controller for managing transient rotor current and overcharging of the DC-link capacitor in order to optimize the operation of the DFIG during network faults. One conventional design choice combines a crowbar circuit with a DC-chopper, in contrast the other design option proposes integrating a modified protection scheme (MPS) that includes an RpLp parallel circuit with the traditional crowbar. Both schemes are placed between the rotor windings and the rotor-side converter (RSC) to boost the low voltage ride-through (LVRT) capacity of the generator. The comparison of results obtained through MATLAB/SIMULINK simulations reveals the successful performance of these two schemes in reducing elevated intensity current of rotor and DC-link voltage levels in the DFIG machine. Furthermore, the traditional crowbar and MPS circuit design have effectively limited the current intensity of the RSC converter to levels lower than 0.22 kA and 2.95 kA, while absorbing up to 2.53 kA and 1.53 kA respectively. Thus, ensuring that the DC-link tension stays within the safe range when network failures occur. The notable distinction is that the MPS design prevents the decoupling of the rotor from the RSC during a symmetrical voltage dip, enabling effective control of all stator power through the RSC. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control 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 Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control 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.)

Field‐oriented control (FOC) has been broadly used as an accurate control method for electric drives. The traditional FOC approach has been effectively developed to 3‐phase induction motor (3φ IM) drive systems in recent decades. Despite the usefulness of FOC methods during normal condition, these strategies are unable to control a wye‐connected 3φ IM (3φ IMy) under the stator winding open circuit fault (SWOCF). This paper discusses modified indirect rotor FOC (FOCIR) strategies for 3φ IMy drives under the SWOCF. The αβ$\alpha \beta $ stationary reference frame (RF) model is presented and utilized to develop vector control systems for the faulty 3φ IMy using asymmetrical transformations. This model is also used to propose a modified FOCIR method for 3φ IMy drives against the SWOCF based on the symmetrical/traditional transformation and using the bi‐voltage controller. The performances of the presented control methods are confirmed via simulations and experiments for a 3φ IMy considering the SWOCF. The achieved results show the effectiveness of modified FOCIR strategies for vector control of the faulty 3φ IMy drive. [ABSTRACT FROM AUTHOR]

Inter-turn short circuit (ITSC) is a common fault in induction motors. However, it is challenging to detect the early stage of ITSC fault. To address this issue, this paper proposes an ITSC fault detection method for three-phase induction motors based on start-up current envelope energy. This approach uses Akima interpolation to calculate the envelope of the measured start-up current of the induction motor. A Gaussian window weighting is applied to eliminate endpoint effects caused by the initial phase angle, and the enveloping energy is obtained using the energy formula as the fault feature. Finally, by combining this with the support vector machine (SVM) classification learner, fault detection of ITSC in induction motors is achieved. The experimental results show that the average accuracy of this method reaches 96.9%, which can quickly and accurately detect ITSC faults in asynchronous motors and determine the severity of the faults. Furthermore, the average accuracy of SVM in detecting early ITSC faults under no-load conditions is 98.8%, which is higher than other classification learners, including LR, KNN, and NN. This study provides a new idea for induction motor fault detection and can contribute to induction motor maintenance. [ABSTRACT FROM AUTHOR]

Multi-vector model predictive control (MPC) of permanent magnet synchronous motors (PMSM) has two issues: selecting the optimal voltage vector (VV) combination is very complicated, and multiple prediction calculations to minimize the cost function result in a heavy computational burden; applying a VV with a short duration may generate narrow pulses, while the effect of reducing torque ripples and stator current harmonics is not obvious. The hybrid-vector model prediction flux control (HV-MPFC) strategy considering narrow pulse suppression is proposed in this paper. First, the optimal VV combination is quickly identified by the sector where the stator flux error vector is located, which lowers the control complexity and computational burden. Secondly, by the relationship between the action time of three VVs and the set time threshold, the hybrid-vector strategy to switch among three VVs, two VVs, and a single VV is employed to prevent the generation of narrow pulses. Finally, experimental results show that, compared with the existing three-vector MPC strategy, the HV-MPFC strategy effectively suppresses the generation of narrow pulses and achieves smaller torque ripples and stator current harmonics at the same switching frequency. [ABSTRACT FROM AUTHOR]

Direct-torque-control-driven permanent magnet synchronous machines eliminate the need for a position sensor while providing improved torque dynamics. However, the structure, regulation principle and nature of compensation of hysteresis-based controllers used in direct torque control impacts performance under faulty operating conditions. This paper analyzes the reaction of direct torque control to the presence of various faults that occur in permanent magnet synchronous machines. The analysis presented reveals that the direct torque control injects a negative sequence voltage and manipulates the torque angle to meet the control objectives when a fault occurs. The co-simulation of finite element analysis and a multi-physic circuit simulator is used to validate the response of the hysteresis-based controller to the machine health. The results indicate that the hysteresis comparators have the ability to mask the impact of the faults in the direct-torque-control-driven permanent magnet synchronous machines. [ABSTRACT FROM AUTHOR]

For effective identification of rub-impact faults between rotor and stator of equipment, the paper has contributed the method integrating dual complexity parameters and variational mode decomposition (VMD). Firstly, to effectively separate the fault characteristics involved in signals, VMD algorithm was applied to decompose vibration signals and the component signals were obtained; secondly, taking account of the large difference of fault feature information involved in different component signals and in order to make options of sensitive fault component signals and reduce the loss of fault features, multi-scale Lempel–Ziv complexity and complexity parameter in Hjorth parameters were brought. Starting from 2 different perspectives of complexity evaluation, choose from the sensitive component signals containing more fault characteristics with these 2 complexity parameters; thirdly, signals were reconstructed based on selected sensitive component signals, and meanwhile, singular value difference spectrum algorithm was used to denoise reconstructed signals to further lessen the influence of noises; finally, the rub-impact fault between rotor and stator was identified by square demodulation spectrum (SDS) of denoised signal. The effectiveness of the proposed method has been proved by comparative analysis with other approaches as well as validation analysis of rub-impact fault signals in multiple situations. [ABSTRACT FROM AUTHOR]

Post‐fault control of a 3‐phase Induction Motor (IM) drive under the Stator winding Open‐Circuit Fault (SOCF) has gained significant importance in recent years especially for safety‐critical industrial applications. Nevertheless, most of proposed schemes suffer from low accuracy or high complexity. In this research, a novel control scheme for improving reliability of wye‐connected 3‐phase IM drives under the SOCF according to Direct Field‐Oriented Control (DFOC) is proposed and evaluated. In the proposed system, different transformations are presented and employed to control the faulty system. The controller is achieved by minor modifications in the traditional control scheme structure. In the proposed system, an Extended Kalman Filter (EKF) is also used to estimate the rotor flux. The designed EKF‐based DFOC (DFOCEKF) is verified using simulations and experimental tests conducted on a 0.75 kW 3‐phase IM drive. Based on the results it can be calculated that the torque ripple is decreased clearly after the proposed fault‐tolerant control approach is applied. The DFOCEKF strategy can control the faulty motor accurately, which can further improve the reliability of IM drive systems. The results also confirmed that the proposed controller after the SOCF has faster dynamic response and higher accuracy compared to previous published papers. [ABSTRACT FROM AUTHOR]

Compressor rotor blade tip winglet technology has been confirmed to be a passive flow control method that is effective in increasing the operating stability of compressors. As revealed by extensive research, the structural parameters of tip winglets are capable of affecting their stability expansion effect, whereas their mechanism and influence law of the compressor stage remains unclear. In this study, the effect exerted by the chordwise distribution of tip winglets on the stability of a high-load compressor stage was investigated. As indicated by the result of this study, the tip winglet exhibiting a proper widest position and an adequate chordwise length can effectively increase the stall margin. To be specific, the widest position was located at 25% chord, and the stall margin was increased by up to 25.39%. A winglet exhibiting a chordwise length of 50% achieved the stability expansion ability equivalent to winglet with a full chordwise length, which can be increased by 22.58%. The tip leakage flow turned out to be weakened as the axial momentum was increased, and the circumferential momentum of the flow that arose from the tip winglet was reduced. The result of this study also suggested that tip winglets can play a certain role in combing the inflow of the stator, such that the blockage of the stator channel can be reduced. [ABSTRACT FROM AUTHOR]

In this paper, the influence of stator teeth deformation on electromagnetic force and acoustic noise of claw pole alternators was investigated. The characteristics of stator teeth deformation caused by welding and assembly were first illustrated, and the influence of stator teeth deformation on the frequency and spatial order of electromagnetic force harmonics was deduced analytically. Then the electromagnetic forces of three alternators with different stator teeth deformation types were simulated by the finite element method, and compared with the electromagnetic force of nominal alternator. In addition, a multi-physics simulation model was established and the electromagnetic noise of the above three different stator teeth deformation alternators was calculated. Finally, the changes in phase current and output current of claw pole alternator with and without stator teeth deformation were analyzed. The analysis results were verified by back-EMF bench test and noise bench test. Results showed that although stator teeth deformation would not change the frequency components of the electromagnetic force, but would generate additional electromagnetic force harmonics. When the number of deformed teeth was not an integer multiple of the rotor pole-pair number, the electromagnetic force harmonics with extra spatial order would appear. [ABSTRACT FROM AUTHOR]

The Direct Torque Control (DTC) was previously designed to achieve high performance of induction motor (IM) by accurately and independently controlling its flux and torque. However, this classical DTC generates several disadvantages such as strong fluctuations in the torque and stator flux as well as quite significant switching losses. For these reasons, many modern techniques have been proposed in the literature to improve it. On the other hand, as the inadequacy of the parameters seriously affects the efficiency and stability of the induction motor, it is paramount to accurately estimate the stator resistance, for this, robust observers are necessary suggested to be employed. This paper proposes developed structure of DTC strategy using twelve sectors combined with Backstepping speed regulator for the external loop and robust model reference adaptive system based on active power principle to estimate the stator resistance. In addition, several simulations under Matlab/Simulink and experiment results using the dSPACE DS1104 board are discussed to confirm improvements in control and speed estimation. [ABSTRACT FROM AUTHOR]

In phase coordinates, a mathematical model of a three-winding asynchronous machine with two windings on the stator as a structural element of electric drives and asynchronous generators with inverter and inverter-capacitor excitation for autonomous electric power plants, oriented to explicit methods of numerical integration of the system of differential equations, has been developed. The model takes into account the displacement angle between two stator windings in the range of 360º and other important factors affecting the course of electromagnetic processes occurring in the machine. On the basis of the mathematical model, a program code was developed as a means of computer verification of machine operation modes. The results of computer study performed with the help of the code confirm the suitability of the mathematical model of a three-winding asynchronous machine to take into account the influence of the displacement angle between the stator windings and their simultaneous and single power supply during the operation of the machine in motor mode. [ABSTRACT FROM AUTHOR]

To realize high performance and suppress the backward motion of the inertia piezoelectric actuator, a novel inertial piezoelectric actuator with double-stator cooperative motion is proposed, designed, fabricated, and tested. The structure and the operation principle of the proposed actuator are first explained in detail. Then the flexible structure is analyzed through the finite element simulation. In addition, the dynamic model of the actuator with double-stator working mode is established and simulated in MATLAB/Simulink, and the step characteristic is investigated, which provided a guidance for the design and optimization of inertial piezoelectric actuators with double-stator. Finally, an experimental investigation of the proposed actuator prototype was carried out and the results showed a significant improvement in the performance of the proposed actuator compared to the previous double-stator inertial piezoelectric actuators. The actuator exhibits a maximum speed of 32.84 mm/s, a maximum lateral load of 20 N, a maximum vertical load of 200 N, a minimum backward rate of 0.91%, and a minimum resolution of 127.5 nm. The actuator with double-stator can improve the maximum output performance to a certain extent, and suppress the backward rate, presenting a specific reference value for the design of future high-performance piezoelectric actuators. [ABSTRACT FROM AUTHOR]

The paper considers the model predictive current control (MPCC) of an induction motor (IM) drive and evaluates five IM models of different complexities—from conventional to magnetic saturation, iron losses, and stray-load losses—for the MPCC design. The validity of each considered IM model and the corresponding MPCC algorithm is evaluated by comparison of the following performance metrics: the total harmonic distortion of the stator current, the average switching frequency, the rotor flux magnitude error, the rotor flux angle error, and the product of the first two metrics. The metrics' values are determined in wide ranges of the rotor speed (0.1–1 p.u.) and load torque (0–1 p.u.) through simulations performed in the MATLAB Simulink environment. The obtained results allow us to identify the IM model that offers the best tradeoff between the practicability and accuracy. Furthermore, a control effort penalization (CEP) is suggested to reduce the average switching frequency and, hence, the power converter losses. This involves constraining the simultaneous switching to a maximum of two branches of the three-phase power converter, as well as inclusion of the weighted switching penalization term in the cost function. Finally, the performance—both steady-state and dynamic—of the proposed MPCC system with CEP is compared with that of the analogous field-oriented controlled (FOC) IM drive. The inverter switching frequency is reduced more than twice by including the frequency-dependent iron-loss resistance in the MPCC. It is additionally reduced by implementing the proposed CEP strategy without sacrificing many other performance metrics, thus achieving a performance comparable to the FOC IM drive. [ABSTRACT FROM AUTHOR]

The doubly fed induction generator (DFIG) is vulnerable to grid faults due to its direct stator connection, causing issues like excess stator current during voltage dips. Consequently, sensitive inverters suffer from increased currents, and the DC-link capacitor undergoes overcharging. This document examines two protection strategies employing a proportional–integral (PI) controller to manage the transient rotor current and mitigate DC-link overcharging, thereby optimizing DFIG behavior during network faults. One option combines a classic crowbar circuit with a DC-chopper, while the other is a modified protection scheme (MPS) that includes an impedance with passive elements and a crowbar. The impedance forms a resistance Rp parallel with an inductance Lp. Both configurations, situated between the rotor coils and the rotor-side converter (RSC), augment the capacity for low-voltage ride-through (LVRT). MATLAB/SIMULINK simulations of the two schemes demonstrate successful rotor current reduction at 2.9 kA and 3.4 kA, and DC-link tension reduction below and at 1.4 KV. In addition, the conventional crowbar and MPS configurations efficiently restrict the RSC current to levels below 0.21 kA and 2.94 kA, while absorbing up to 2.52 kA and 1.52 kA, respectively. The key difference lies in the fact that fine-tuning the parameters in the MPS design prevents rotor disconnection when faced with a balanced fault. This enhancement enhances machine performance and enables full stator power control via the RSC. [ABSTRACT FROM AUTHOR]