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Variable-speed electrical drive control typically relies upon a two-loop scheme, one for torque/speed and another for stator current control. In modern drive control methods, the actual mechanical speed is needed for both loops. In practical applications, the speed is often acquired by incremental rotary encoders. The most used method derives speed from an encoder pulse count during a fixed amount of time. It is known that this sensing method produces time delay in the speed feedback loop as well as fluctuations in the speed measurements. Time lags produce phase loss that has potentially negative effects on the overall drive performance. Nevertheless, the pulse counting method is favored in most cases due to its simplicity and existing support for its use in digital signal processors. In this paper, a new speed sensing method is proposed to reduce time lag without incurring increased fluctuations. The proposal uses a novel transient detector to determine the actual operational regime of the drive: transient or stationary. Transient detection is not based on measured speeds but works directly with the train of incoming encoder pulses. The method is designed to work well with established digital signal processor routines. The proposal is assessed through experimentation on a real five-phase induction motor. [ABSTRACT FROM AUTHOR]

In this study, a hybrid particle swarm optimization (HPSO) approach is presented for enhancing the performance of a three-phase, 12-slot, 19-pole yoke-less axial-field flux-switching permanent magnet (YASA-AFFSPM) motor. The aim of the optimization process is to achieve a motor that demonstrates high efficiency and stable operation. To facilitate this, a finite element analysis model is developed, and a multi-objective optimization function utilizing weight coefficients is created. The variables in this study include the split ratio, stator axial length, sandwiching pole angle, rotor pole angle, permanent magnet arc, and the number of conductors per slot. The optimization objectives encompass efficiency, power factor, cogging torque, and average torque, evaluated under both no-load and load conditions. Findings indicate that the hybrid particle swarm optimization method excels in its search capabilities and convergence speed, resulting in motor designs that align closely with the intended specifications. Finite element simulations further validate the proposed methodology's effectiveness and practicality. Finally, experimental results are presented to confirm the reliability of the suggested algorithm. [ABSTRACT FROM AUTHOR]

ABSTRACT For the insulation diagnosis of stator windings of generators, sampling surveys are conducted on the coils to estimate the dielectric strength of the stator winding. Previous research has relied on inferring the breakdown voltage of the stator winding from the value 3σ away from the mean value of the breakdown voltage of the coil. However, this conventional method exhibits a significant estimation error when the sample size is small. Therefore, we propose a method for estimating the breakdown voltage of the stator winding based on the maximum value of the partial discharge magnitude and the minimum value of the breakdown voltage of the sample coil. We verify this method by Monte Carlo simulation assuming a sampling survey of coils. [ABSTRACT FROM AUTHOR]

Detecting Broken Rotor Bars (BBFs) in induction motors is critical for ensuring their reliable operation. While conventional methods, such as Fast Fourier Transform analysis of stator current spectra, have been widely used for BBF detection, they suffer from limitations like spectral leakage and low-frequency resolution. The Welch Transform is known for effectively reducing spectral leakage and noise when analyzing finite data. This paper presented an innovative FPGA-based architecture for real-time implementation of Welch transform for BBFs in induction motor diagnostics accompanied by a novel right-band-based detection technique, and the architectures are explained in detail. We conducted experiments to verify the effectiveness of the proposed architectures, including applying BBF faults under varying loads and severity levels. The results demonstrated the efficiency of our proposed architectures, as it was found that resource consumption rates were meagre, and error indicators were obvious. The results were displayed in real-time through a user-friendly graphical interface, demonstrating the practical effectiveness of the FPGA-based solution. [ABSTRACT FROM AUTHOR]

The paper proposes a novel speed sensor‐less stator flux‐oriented vector control of dual‐stator induction generator suitable for high‐power applications in grid‐tied wind energy conversion system. In this control strategy, the magnitude and angle of the flux are directly estimated by the measured stator voltages and currents. As the voltage and current sensors are placed on the stationery stator part, therefore, the proposed control strategy does not affect the robustness of the machine compared to the conventional rotor flux‐oriented vector control where the sensors need to be mounted on the rotating part of the machine. Moreover, the proposed speed encoder‐less stator flux‐oriented vector control eliminates the use of speed encoder, thereby reducing the cost and eliminating the error caused due to faulty speed measurement by the speed encoder of the overall system. The performance of the novel speed sensor‐less stator flux‐oriented vector control scheme has been verified by simulation and then experimentally on a 2 hp, 415 V, 50 Hz, three‐phase dual‐stator induction generator drive. The control strategy was implemented through dSPACE 1104 DAC card. From the simulated and the experimental results, it is evident that the proposed control strategy reflects improved performance w.r.t. conventional rotor flux‐oriented vector control. [ABSTRACT FROM AUTHOR]

This paper proposes a novel consequent‐pole dual‐stator linear permanent magnet vernier machine (DS‐LPMVM) with PM in the mover slot opening, which has a bi‐directional flux modulation effect. The novelty of the proposed machine consists of consequent‐pole double‐sided topology with toroidal windings placed in the mover slot, as well as PMs both on the stator and mover slot to improve the air gap magnetic field. The dual‐stator adopts misalignment structure to suppress detent force and produce steady thrust. The electromagnetic parameters of the proposed DS‐LPMVM are evaluated and quantitatively compared with the conventional linear permanent magnet vernier machine (C‐LPMVM) in terms of air‐gap flux density, no‐load back EMF, inductance, and thrust. The geometrical parameters are designed to reduce the detent force. By analyzing the optimized structure parameters of the two machines, the good electromagnetic performances of the proposed machine are verified by the finite element method (FEM) and semi‐analytical method, and both results of the two methods are basically the same. It is found that the amount of PMs for the proposed machine is reduced by 20% compared to the C‐LPMVM, but the average thrust is increased by 20.7% and the thrust ripple is reduced to 4.04%. The results show that the proposed DS‐LPMVM has better flux modulation effect and thrust characteristics than C‐LPMCM. Finally, a 12‐slot, 10‐pole pairs prototype was manufactured and tested. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This study reports the test results of a total of 16 low‐voltage (415 V) 15 and 30 kVA alternators manufactured using optimized polyester resin nanocomposites. These tests consist of the open‐circuit characteristics (OCC), short‐circuit characteristics (SCC), voltage regulation, and temperature rise tests. The test results obtained are reported in terms of efficiency, voltage regulation, OCC and SCC curves, and temperature rise in stator and rotor windings. The results show that the temperature rise in the windings reduced significantly and the efficiency improved marginally using polyester resin nanocomposite insulation. Finally, the calculations show that the reduction in temperature rise can double the life of the alternator. Notably, the manufactured alternators passed all the performance tests as per the test standards, without adversely affecting its performance. For the insulation design of any low‐voltage rotating machine utilizing polyester resin as its base insulation, a similar approach can thus be adopted. Highlights: Fabrication of alternator prototype using polyester nanocomposite insulation.Alternator prototype fabrication using standard industry manufacturing process.Reduction in temperature rise in stator and rotor windings by 10 °C.Enhancement in alternator efficiency by 3%–4%.Polyester nanocomposite insulation doubles the service life of alternator. [ABSTRACT FROM AUTHOR]

The fundamental idea underlying the research presented in this paper was the desire to use less magnetically charged areas of the general construction of induction machines by increasing the active working surface by interposing a new internal stator armature. This results in a new air gap and foreshadows the advantage of increasing the torques developed by the motor considered, compared to the equivalent standard motor, at the same volume of iron. The following research-validation methods were followed: theoretical studies (analytical simulation and FEM), an experimental model (prototype), and testing on the experimental platform. We recall obtaining solid conclusions on the technological construction, functional and energy characteristics, as well as superior performances of over 50% regarding electromagnetic torques compared to the equivalent classic version. The prototype of this type of machine was surprising due to the ease with which the rotor can be rotated, highlighting the reduced inertia. In conclusion, concerning the problem addressed and the objectives pursued, the research had, in essence, an applied and experimental nature. The recent development of permanent-magnet synchronous motor constructions has led to the concept of creating such motors in the constructive configuration specified in the paper (two stators and two radial air gaps). [ABSTRACT FROM AUTHOR]

The power control system structures for a doubly‐fed generator (DFIG) are proposed. The classical field oriented control and the feedback control with the multi‐scalar variables were considered. The generator is working in the AC grid connection mode. The rotor side of the generator is connected to the current source converter (CSC); the stator is directly related to the AC grid. The static feedback linearization using the multi‐scalar variables of DFIG is proposed to increase active and reactive power control accuracy. The proposed control structure allows to linearize the generator system, and decoupled between the control paths. The proposed approach can be called voltage control because one of the control variables is the voltage in the DC‐link of the CSC. The simulation and experimental investigations in the 2 kW DFIG system consider the AC grid voltage dips, confirming that the proposed control system remains stable. [ABSTRACT FROM AUTHOR]

Wall roughness in centrifugal pump side chambers significantly affects flow behavior and overall pump performance, yet current research in this area is limited. This study investigates the effects of rough rotor, rough stator, and rough rotor–stator on side chamber flow using numerical simulations and experimental validation. A simplified model is proposed to reduce computational costs, and its accuracy is verified by comparison with a typical centrifugal pump. Using the entropy generation method, the local energy loss and macroscopic fluctuations due to roughness are analyzed. The results show that the effect of rotor roughness plays a dominant role, while the effect of stator face roughness is relatively small. The roughness of the pump chamber walls leads to an increase in centrifugal pump head and a decrease in efficiency. The maximum increase in the centrifugal pump head reaches 1.66% and the maximum decrease in efficiency reaches 1.51% in the studied range. These findings indicate that wall roughness is a key factor in flow losses and potential system instability, with the simplified model offering quick and accurate predictions. [ABSTRACT FROM AUTHOR]

This work addresses the position tracking control design of the stator vane driven by electro-hydrostatic actuators facing uncertain aerodynamic disturbances. Rapidly changing aerodynamic conditions impose complex disturbance torques on the guide vanes. Consequently, a challenging task is to enhance control precision in complex uncertain environments. Inspired by the principles of mammalian muscle movement, a novel robust control strategy based on the backstepping method has been proposed. Using backstepping, virtual rotational speed and virtual pressure difference force are designed, which decompose the high-order position closed-loop control problem into three lower-order parts, eliminating the need for matching conditions. Subsequently, robust controllers were designed, and stability proofs and performance analyses of the controllers were provided. This control strategy was tested through numerical hydraulic simulation. The results show that compared to other control methods, this approach significantly improves tracking accuracy and robustness. Therefore, it is believed that this method has the potential to become a new generation solution for such problems. [ABSTRACT FROM AUTHOR]

The aim of this paper is to design and Finite Element Analysis (FEA) of a novel rotor topology for a permanent magnet synchronous reluctance machine. According to the advantages and drawbacks of the PMSyncRM and the SPMSM, a conventional PMSyncRM rotor design combined with sur‐face‐mounted magnets is introduced as the SPMSyncRM. The surface‐PM arc size is investigated, so that it is considered as multiplication of an integer coefficient and the angle between two adjacent slots of the stator. The analysis involves simulation of the electromagnetic characteristics and the numerical model of each structure using finite element method. Each E‐Magnetic character is calculated for a better understanding of the benefits of the SPMSyncRM. Applying 2D FEA, the optimised surface‐PM arc size is calculated and the static and dynamic operational behaviour of the SPMSyncRM is simulated. Moreover, short circuit analysis is performed to study the demagnetisation of magnets. All results are reported comparatively considering a conventional PMSyncRM, so that the proposed SPM‐SyncRM topology presents high torque‐power density, lower values of cogging torque, higher values of power factor and efficiency, better static and dynamic performance, and robustness towards demagnetisation. [ABSTRACT FROM AUTHOR]

Doubly fed induction generator (DFIG) is significantly affected by various faults occurring in the grid as they are directly connected to the grid. In order to realize the low voltage ride through (LVRT) capability, the DFIG must remain connected to the system for a certain period of time according to the grid code requirement. In order to achieve this, the high rotor current must be reduced in DFIG against faults occurring on the grid side. In this study, a decoupled feed-forward control model was developed for the LVRT capability. Positive, negative, natural, and forced methods were used for the decoupled feed-forward control (FFC) model. In addition to this developed model, while the stator electromotive force (EMF) model was developed for simulation study performance and ease of calculation, the rotor EMF model was also developed to predict the transient rotor current quickly. The developed models and the conventional model were used and compared in detail. According to the results obtained, it was observed that the system became stable owing to the developed model, while the oscillations formed as a result of the transient stability were damped. [ABSTRACT FROM AUTHOR]

Pole-changing permanent magnet (PCPM) motors have advantages over traditional permanent magnet synchronous motors (PMSM) in high-speed applications. However, changing the pole number of a motor requires reconstructing the stator winding. This increases both the cost and complexity. To solve this problem, a new type of single-winding PCPM motor with a pole-slot combination satisfying the rule of 2pa + 2pb = Z (the sum of the number of poles of the motor before and after the pole-changing is equal to the number of slots) is proposed in this paper. The multi-pole ratio pole-changing of the PCPM motor can be realized by combining the single-winding structure with another single-winding structure that satisfies the pa + pb = Z (the sum of the number of pole pairs of the motor before and after the pole-changing is equal to the number of slots) rule. Through this method, there is no need to reconstruct the stator winding when a pole is changed, Only by changing the phase sequence and direction of the armature current, the switching process is rapid, and the online pole-changing can be realized. This single-winding pole-changing method can flexibly realize the conversion of three pole number modes without increasing the additional winding cost and complexity. Finally, the rationality of the proposed pole-changing method is verified by finite element analysis (FEA). [ABSTRACT FROM AUTHOR]

To improve the adaptability of sensorless control in the full-speed range of a dual three-phase permanent magnet synchronous motor (DTP-PMSM), an improved sensorless control strategy based on a variable-gain super twisting algorithm sliding mode observer (VGSTA-SMO) along with harmonic component compensation has been introduced in this paper. First, the super twisting algorithm sliding mode observer (STA-SMO) is introduced to reduce the inherent chattering phenomenon of traditional SMOs. Then, the variable gain of this STA-SMO is designed to improve the observation adaptability at different rotor speeds. Meanwhile, considering that the harmonic components, especially at low rotor speeds, in the stator current can affect the observation accuracy of this VGSTA-SMO, a least mean squares adaptive notch filter (LMS-ANF) is employed to implement online harmonic compensation. Finally, comparative experiments with different methods in the full-speed range are conducted and compared to verify the effectiveness of the proposed novel sensorless control strategy whose observation deviation is about 2% even when the rotor speed is as low as 100 rpm. [ABSTRACT FROM AUTHOR]

Motor current signature analysis (MCSA) offers a non-invasive approach to early detect different faults in squirrel-cage induction motors (SCIMs). Every fault normally adds some specific harmonics to the motor current and the MCSA typically proposes the fault diagnosis by detecting these harmonics. Using the rotor–stator mutual-inductance curve, this paper proposes an analytical approach to determine broad sets of harmonics that are presenting in the healthy SCIM current or are adding to the current by broken rotor bar (BRB) fault, mixed eccentricity (ME) fault and combined BRB-ME fault. The broad harmonic sets are attained due to applying exact form of the inverse of the air gap function, using exact form of the stator and rotor turn functions and taking every integer harmonic of the stator current into account. The extensive harmonic sets give higher degrees of freedom to attain the most appropriate harmonics to establish fault diagnosis techniques. Further study shows that many BRB-related harmonics are also present in the healthy state with lower amplitudes and that the ME fault magnifies some well-known BRB-related harmonics as well as the 3rd harmonic. In addition, the combined BRB-ME fault produces harmonics that are sidebands around the harmonics produced by the single ME or BRB fault. Simulation results based on the finite elements method and corresponding experimental test results confirm the analytically achieved results. [ABSTRACT FROM AUTHOR]

The flux observer method is widely utilized as a sensorless control technique in which the stator or rotor flux of IPMSM can be measured with a closed-loop observer or an integrator. However, DC-offset (DCoff), the ramp signal, and harmonics are consistently present in the acquired rotor flux because of an unidentified starting value, errors in the integral computation's current detection, and the inverter's nonlinearity. The aforementioned interference signals will drastically reduce the sensorless control efficacy. This work introduces an enhanced flux estimator with a negative feedback loop and PI controller to overcome the DC drift problem resulting from a pure integrator and a low-pass filter. Moreover, an optimal design approach of flux estimator structures with a broad range of speeds for Interior permanent magnet synchronous motor (IPMSM) drives is proposed, which utilizes an integrated topology of the voltage and current models incorporating a DC-offset PI-correction loop, actual and estimated flux magnitude's correction error. The flux vector's initial inaccuracy is eliminated, together with the DCoff and drift in the acquisition channel. A phase-locked-loop state estimator is utilized to derive the speed and position from the actual and estimated flux. The effectiveness and superiority of the suggested approach were proven by simulation and experimental findings for the IPMSM drives, which displayed high dynamic performances over varying scenarios. This reliable approach, including sensorless control, is suitable for all AC motors with sinusoidal flux distributions over a wide speed range. [ABSTRACT FROM AUTHOR]

The sensitivity of speed estimators for parameter variations presents a significant challenge for sensorless Induction Motor (IM) drives, particularly at very low speeds. This paper examines the impact of parameter variations and the PI adaptation mechanism on the stator current-based Model Reference Adaptive System (MRAS). In contrast to the estimation of rotor flux, the MRAS method uses the observed stator current and the stator current estimate error within the adjustable IM model. The stability analysis for changes in machine parameters and PI controller gains is examined using small-signal perturbation. Additionally, a sensitivity analysis of stator and rotor resistance changes is included. A complete simulation using MATLAB/Simulink and experimental validation using a laboratory prototype based on the DSP-DS1103 are provided. The analytical, modeling, and measurement results reveal that the suggested observer responds well and provides precise speed estimation in all four quadrants of operation. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny 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.)

In this work, a linear quadratic regulator controller is utilized to optimize the gains of the machine-side converter and grid-side converter controllers. The DC-link voltage and the rotational speed of the doubly-fed induction generator are optimally regulated by these controls. Additionally, the small-signal stability of the proposed system has been evaluated using the linearized model of the system. The small-signal stability analysis of the designed system has been accomplished through the application of the eigenvalues and participation factors technique. The suggested controller has been tested in a variety of operating conditions under small disturbances. MATLAB/SIMULINK simulation simulations have been used to evaluate the efficacy of the suggested optimal control system. Additionally, the generator-angular speed and DC-link voltage dynamic performances demonstrate the efficacy of the proposed controller. Finally, the robustness of the proposed controller has also been tested and validated using OPAL-RT technology under large perturbations at stator terminal voltage. [ABSTRACT FROM AUTHOR]

This paper presents an advanced automatic fault classification method for detecting rotating rectifier faults in brushless synchronous machines (BSMs). The proposed approach employs a multilayer perceptron (MLP) neural network to classify the operational states of the rotating rectifier, including healthy conditions and common fault types: open-diode (OD), shorted-diode (SD), and open-phase (OP). Key machine measurements, available on an ordinary basis in the industry, such as active power (P), reactive power (Q), stator voltage (U), and excitation current (Ie), are used as inputs for this model, allowing for non-invasive, real-time fault detection. This model achieved an overall classification accuracy of 93.4%, with a precision of 94.9% for fault detection and strong recall performance across multiple fault types. The neural network's robustness is enhanced by advanced data processing techniques, including Gaussian filtering and class balancing through the synthetic minority over-sampling technique (SMOTE). Experimental testing on a modified 5-kVA BSM setup, where rectifier faults were systematically induced, was used to train the network and validate the model's performance. This method provides a promising tool for real-time condition monitoring of BSMs, improving machine reliability and minimizing downtime in industrial applications. [ABSTRACT FROM AUTHOR]

AbstractThe Variable Stator Vanes (VSV) mechanism enhances the stability margin of aero engines by adjusting the vane angles to prevent surging, but the clearances of kinematic joint will affect rotation accuracy of vanes. To investigate the dynamic characteristics of VSV mechanism that simultaneously consider spherical clearance and three-dimensional (3D) rotational joint clearance, an analytical method was developed to study the dynamic characteristics of VSV mechanism Vanes considering mixed clearance. Firstly, a dynamic model incorporating mixed clearances is developed and validated experimentally. Then, the effects of different clearance types, clearance sizes, and mixed clearances are analyzed on the dynamic characteristics of the vane. Finally, the results indicate that an increase in clearance leads to a greater susceptibility of the dynamic characteristics being affected. Taking into account the effects of mixed clearances on dynamic characteristics, which are not merely a straightforward summation of the impacts of two types of clearances, it is crucial to consider the interplay between different types of clearances. The study provides a basis for the modeling and dynamic characteristics analysis of VSV mechanisms taking into account mixed clearances. [ABSTRACT FROM AUTHOR]

Direct torque control with space vector modulation has been increasingly attracting emphasis for permanent‐magnet synchronous machine control, benefiting from a high dynamic response and low torque ripple. However, the rapid tracking performance of torque and stator flux linkage is gradually deteriorating as the machine enters the overmodulation region because of the output‐voltage limitation of the inverter. Therefore, to enhance the system tracking performance in the overmodulation region, an innovative overmodulation method based on torque and flux optimal tracking is proposed. In contrast to the conventional overmodulation method where only one of the torque and stator flux linkage tracking is considered, the proposed strategy first constructs the weightless cost function to achieve a trade‐off control between the torque and stator flux linkage. Then, by using an equivalent geometric path to intuitively express the weightless cost function, the minimum cost function can be easily solved and the optimal output voltage vector can be determined correspondingly, to achieve the fast‐tracking of both the torque and stator flux linkage. Additionally, the voltage utilization of different overmodulation schemes is also analysed. Finally, the experimental results demonstrate the efficiency and practicality of the proposed strategy. [ABSTRACT FROM AUTHOR]

The high-performance vector control technology of permanent magnet synchronous machines (PMSMs) relies on high-precision rotor position. The Hall-effect sensor has the advantages of low cost, simple installation, and strong anti-interference ability. However, it can only provide six discrete rotor angles in an electrical cycle, which makes high-precision vector control of PMSMs difficult. Hence, to obtain the necessary rotor position of PMSMs, a rotor position fitting method combining the Hall signal and machine flux information is proposed. Firstly, the rotor position signal output by the Hall-effect sensors is used to calibrate and update the stator flux obtained under pure integration. Then, based on the corrected stator flux and its relationship with current and angle, the rotor position and speed are obtained. Experimental verification shows that the rotor position observer combining Hall signal and flux information can reduce the initial value bias and integral drift caused by traditional average speed method hysteresis and pure integration method calculation of flux and can quickly and accurately track and estimate the rotor position, achieving high-performance vector control of PMSMs. [ABSTRACT FROM AUTHOR]

Protection of synchronous generators (SGs) against internal faults, such as stator earth fault (SEF) and turn‐to‐turn fault (TTF), is crucial for ensuring the stability and security of the power system. This paper presents a phase domain model for simulating SEF and TTF in SGs, requiring only nameplate data and avoiding the need for complex geometric data or lengthy simulations typical of FEM models. The stator winding is divided into three sections, allowing for the calculation of magnetic field distribution in both healthy and faulty conditions. The model is capable of simulating short‐circuit turns at various locations within the stator winding with high accuracy and speed. The dynamic response of the generator is also incorporated into the model. The model's accuracy is validated through comparison with results from multiphysics simulation software. Furthermore, this study addresses the limitations of conventional protection methods in detecting TTF and proposes a novel, simple, fast, and accurate protection logic that can be implemented in digital protection relays and is effective across a wide range of TTF scenarios. [ABSTRACT FROM AUTHOR]

Towards complex coupled molecular motions, the remote handedness inversion of a helicene moiety was achieved by a rotary molecular motor. The use of a specifically engineered dynamic helicene stator in a novel overcrowded‐alkene second‐generation molecular motor based on a fluorinated dibenzofluorene fragment allows for an unprecedented control over helicity inversion. This is achieved by the mechanical coupling of the rotation of the rotor to the helicene inversion of the stator half via a remote chirality transmission process. Thus, the unidirectional rotary motion generated upon irradiation is used to invert the dynamic stereochemistry of a helicene, leading to a 6‐step cycle with eight intermediates. In this cycle, both alternation between P and M configurations of the helicene stator and dynamic thermal interconversion (paddling motion) can be achieved. In‐depth computational and spectroscopic studies were performed to support the associated mechanism. The control over coupled motion and dynamic helicity offers prospects for the development of complex responsive systems. [ABSTRACT FROM AUTHOR]

MotY homologs are present in a variety of monotrichous bacterial strains and are thought to form an additional structural T ring in flagellar motors. While MotY potentially plays an important role in motor torque generation, its impact on motor output dynamics remains poorly understood. In this study, we investigate the role of MotY in P. aeruginosa, elucidating its interactions with the two sets of stator units (MotAB and MotCD) using Förster resonance energy transfer (FRET) assays. Employing a newly developed bead assay, we characterize the dynamic behavior of flagellar motors in motY mutants, identifying MotY as the key functional protein to affect the clockwise bias of naturally unbiased motors in P. aeruginosa. Our findings reveal that MotY enhances stator assembly efficiency without affecting the overall assembly of the flagellar structure. Additionally, we demonstrate that MotY is essential for maintaining motor torque and regulating switching rates. Our study highlights the physiological significance of MotY in fine-tuning flagellar motor function in complex environments. [ABSTRACT FROM AUTHOR]

In the traditional predictive torque control strategy, the cost function considers two different control objectives: stator flux and torque. Therefore, it is necessary to reasonably set the weighting factor to ensure that the optimal voltage vector is accurately selected during the control process, thereby achieving better torque and flux control performance. In view of the complex tuning process caused by traditional predictive torque control setting method of weighting factor, a new weighting factor selection method for permanent magnet synchronous motor control system is proposed in this paper. The derivation process is based on the equivalent transformation between the torque–flux prediction and the voltage vector prediction. If both the cost functions of the torque–flux and voltage vector reach their minimum values, the same output voltage vector will be selected. Compared with previous studies, the algorithm proposed in this paper can find the precise location of the optimal weighting factor without changing the form of the cost function, which simplifies the parameter tuning process. Experimental results are also provided to validate the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This study addresses the technical challenge that conventional self-recirculating casing treatments predominantly enhance the compressor stability with minimal efficiency gains. Focusing on a transonic axial flow compressor, National Aeronautics and Space Administration Stage35, the research designed an innovative stator suction-type self-circulating casing treatment (SS-SCT), which features the suction slots on the stator instead of the traditional self-circulating casing treatment's suction port. Using multipassage unsteady numerical simulations, this paper investigated the underlying mechanisms by which the SS-SCT affects the compressor performance. The numerical results reveal that the SS-SCT not only increases the compressor stall margin by 3.36% but also enhances the efficiency by 0.13% at the design point and by 0.6% at the near-stall point. The jetting action of the SS-SCT mitigates the detrimental effects of the rotor tip leakage flow and alleviates the blockages in the rotor tip passage at the near-stall point, thereby improving the compressor stability. Concurrently, the suction slots extract the low-speed fluid generated by the boundary layer separation in the stator passage, reducing flow losses, and consequently enhancing the compressor efficiency. [ABSTRACT FROM AUTHOR]

Research on multicomponent interactions in aero-engine design technology has gained significant attention. The presence of hot streak (HS) at the combustor exit is critical, as it affects the turbine aerodynamic performance and the heat transfer properties of the blades. This paper presents the design of a HS simulator for a 1.5-stage turbine rig, examining the transportation and attenuation mechanisms of HS at two circumferential clocking positions and temperature ratios. Numerical simulations were conducted using commonly employed two-equation turbulence models with varying turbulent Prandtl numbers (Prt). Results show that the choice of turbulence model and Prt value greatly influences the prediction precision of HS dissipation. The numerical method effectively predicts the HS attenuation levels at the exits of stator 1 (S1), rotor (R), and stator 2 (S2), while the radial migration of HS core is not well captured. The HS experiences an overall attenuation rate of 75%–85% in the 1.5-stage turbine. Both clocking positions and temperature ratios significantly impact the HS attenuation levels, although the extent of the effects varies across the three rows of blade. The HS core tends to migrate radially inward within the turbine stage, influenced by curvature, buoyancy, and secondary flow effects. The extent of these influences is still determined by the clocking positions, temperature ratios, and the specific blade rows. [ABSTRACT FROM AUTHOR]

Multiphase permanent magnet synchronous motors (PMSMs) have attracted much more attention for their high efficiency, low torque ripple and good fault tolerance. However, open‐circuit fault results in asymmetrical motor behaviour, and deteriorates torque performance, especially dynamic response. This paper proposes a novel fault‐tolerant direct torque and flux control (DTFC) strategy to restrain fluctuating torque and enhance torque dynamic performance of a five‐phase PMSM with open‐circuit fault. The novelty of the proposed strategy is the development of DTFC based on stator flux orientation under the open‐circuit fault condition and the third harmonic current suppression with carrier‐based pulse width modulation technology. Consequently, the decoupling control of torque and stator flux can be achieved under the open‐circuit fault condition, and the third harmonic current can be restrained without additional control. Combined with deadbeat control, the heavy computation burden can be reduced. Thus, the proposed strategy not only can enhance torque dynamic performance under open‐circuit fault operation, but also keep smooth torque with circular stator flux trajectory before and after open‐circuit fault. The effectiveness of the proposed strategy is verified by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

The cogging torque is usually considered as an adverse effect of the PM machine servo system. This paper presents a new perspective that the cogging torque can be exploited in many practical situations as long as the speed ripple can be suppressed. By the proposed cogging torque design scheme, the local core saturation on the stator yoke can be constructed by specially designing the yoke structure. With this idea, the cogging torque distribution can be designed, with the transmission ratio, generating a series of designated auxiliary positioning forces on the load side. This weak positioning force will be amplified by the reduction gears and make the terminal servo load prone to stop at the designated stable equilibrium positions. This feature can help humans conveniently move the load to some designated positions by manual mode with a certain precision. Considering the negative impact of this constructed cogging effect, a speed ripple suppression method is applied to guarantee that the cogging torque machine can provide a good servo performance. The designated cogging torque and performances are verified by prototype machines, testing, and motion control experiments. [ABSTRACT FROM AUTHOR]

Winding inductance always plays a key role in the electromagnetic performances of stator surface-mounted permanent magnet (SSPM) machines, including their flux-weakening capability, prospective fault current, power factor, current ripple, etc. Generally speaking, winding inductance mainly comprises three components: an air-gap component, a slot-leakage component, and an end-leakage component. In this paper, firstly, the winding pole pairs of SSPM machines are investigated based on the magneto-motive force-permeance model, through which the winding configurations can also be determined. Then, according to the winding configurations, three analytical expressions for each inductance component are derived to evaluate the winding inductance per phase. In addition, finite element analysis (FEA) is employed to verify the effectiveness of the derived analytical expressions. Meanwhile, three prototyped SSPM machines are manufactured, and their winding inductances are measured to further verify the analytical expressions. The measured results agree with both the analytical and FEA results very well. [ABSTRACT FROM AUTHOR]

Summary: Compared with asynchronous voltage modulations, the synchronous space vector modulation (Syn‐SVPWM) can suppress current harmonics for high‐power induction motors (IM) by generating symmetrical voltage pulses. However, it is difficult to build a high‐performance current regulator based on Syn‐SVPWM because of the requirements of fixed voltage phases and the nonsymmetrical switching sequences in Syn‐SVPWM. Therefore, this manuscript proposes the equivalent realization of Syn‐SVPWM by the concept of stator flux trajectory tracking (SFTT). The new method controls the stator flux vector to move along evenly distributed flux samples in the complex plane. Then, the synchronization and symmetries of voltage pulses are maintained by organizing the switching sequence between adjacent flux samples. Meanwhile, the torque can be changed by online updating the control period based on the inverse torque model. Consequently, the proposed method can provide fast torque response with Syn‐SVPWM in a simple manner because it does not have to compensate the phase contradiction and to extract the fundamental of sampled current. Both simulations and experiments have verified the effectiveness of proposed method. [ABSTRACT FROM AUTHOR]

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In this paper, the fault-tolerant operation of an electric-drive-reconstructed onboard charger (EDROC) designed on the basis of an asymmetrical six-phase permanent magnet synchronous machine (ASPMSM) drive is studied and discussed for cases where an open-phase fault (OPF) occurs in any phase. The fault-tolerant operation is realized by rearranging the stator currents, aiming to eliminate the rotating field caused by the OPFs and to ensure the balance of grid currents. Each faulty case is discussed, and the rearranging scheme of stator currents is deduced. Meanwhile, a controller shared for both healthy and faulty cases is designed. Finally, some experiments are conducted to verify the theoretical analyses. [ABSTRACT FROM AUTHOR]

Shock is the main characteristic of supersonic compressors. There are relatively few studies of the control of shock structure and secondary flow in supersonic compressors by nonaxisymmetric endwall optimization. The lack of understanding of the mechanism of flow structure changes in supersonic compressors by the nonaxisymmetric endwall limits the application of this technique in supersonic compressor interiors. In this paper, the effects of nonaxisymmetric endwall on the supersonic compressor and flow mechanism were studied using the numerical simulation method and verified by experiment. The results showed that the optimized nonaxisymmetric endwall design increased the peak isentropic efficiency of the supersonic compressor by 0.6%, verifying the effectiveness of the nonaxisymmetric endwall in improving the supersonic compressor. By comparing the flow fields at the peak efficiency points before and after optimization, it was found that the shock loss in the rotor was reduced by the change of shock structure induced by the nonaxisymmetric endwall, and the secondary flow loss was controlled by the change of shock structure in the rotor. Moreover, the rotor's nonaxisymmetric endwall changed the downstream stator's inlet conditions, reducing the stator's total pressure loss. Therefore, the nonaxisymmetric endwall has a wide range of applications for regulating the internal shock structure of supersonic compressors. [ABSTRACT FROM AUTHOR]

In the variable frequency motor drive system, because the cable impedance does not match the motor impedance, the reflection wave of the voltage wave will be generated. The superposition of reflected voltage waves can lead to overvoltage at the motor ends, which can damage the insulation structure. In this paper, the equivalent circuit models of cable and stator winding are established, respectively. The overvoltage distribution under different power supply frequencies and cable lengths is simulated and analyzed. The influence mechanism of power supply frequency and cable length on the overvoltage distribution of stator winding are studied. The simulation results show that the overvoltage of the first pulse falling edge will be superimposed on the overvoltage of the second pulse rising edge under high-frequency conditions, resulting in a further increase in the overvoltage. The voltage appears in all coils after the middle of the winding. The ground voltage is up to 1.32 times the input voltage, and the inter-turn voltage is up to 9.2 times the average voltage. The increase in cable length will lead to an increase in ground voltage, but the increase in speed will slow down after exceeding the critical length of 300 m. The maximum ground voltage can reach 1.93 times of the input voltage, which is 3.6% different from the calculation result under ideal conditions. The inter-turn voltage changes with the cable length in an N-shaped manner, up to 185 V. The results of this paper are of great significance to further study the insulation design of generator end input. [ABSTRACT FROM AUTHOR]

To maximize the performance of rotating machines, it is essential to establish a design method with minimal arbitrariness. This paper proposes a self‐assembling method to design stator slots for alternating current (AC) rotating machines. First, we develop a line‐current approximation model of the stator winding using pulse‐width modulation technique and realize an ideal spatial magnetic flux density distribution. Subsequently, we design the realistic stator with an acceptable current density of the winding by forming unique slot shapes in a self‐assembling manner under two synthetic conditions using the developed line‐current approximation model as the starting model. The designed stator realizes a rotating magnetic field similar to the conventional design results. Additionally, we perform an analysis of motor rotation characteristics by combining the self‐assembled stator with a surface‐mounted permanent magnet rotor to determine the possibility of a higher output compared to that when using a conventional stator. The self‐assembled motor without relying on empirical rules shows a possibility of further improving the torque characteristics, thereby contributing to designing the AC rotating machines. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper, a state and parameter observer, based on a novel extended Kalman filter (EKF), is designed to solve the parameter variations dependent estimation performance deterioration of induction motor (IM) drive systems. The proposed EKF based observer algorithm performs online estimation of the rotor mechanical speed, stator stationary axis component of the stator currents and rotor fluxes, stator resistance, rotor resistance, reciprocal of the total inertia of the system, and load torque including viscous friction term in a single EKF by using measured rotor mechanical speed and stator currents. Thus, frequency and temperature-dependent variations of the resistances are estimated to be updated in the observer, which leads to control performance enhancement of the IM drive. Moreover, to rise the dynamic performance of the observer, the load torque and reciprocal of the total inertia of the system which are mechanical parameters are also estimated. To verify the robustness of the IM drive and the estimation performance of the proposed observer, they have been tested under challenging scenarios including changes in parameters and speed reference. Moreover, the estimation performance of the proposed ninth order observer is compared with that of a sixth order EKF estimating the same electrical parameters by using directly measured speed. Ultimately, the simulation results obviously reveal the efficacy of the proposed IM drive. [ABSTRACT FROM AUTHOR]

A novel method is presented for determining the derating factors of a three‐phase induction motor under the condition of the unbalanced supply voltages. In this method, a mechanical system is used which consist of the a centrifugal pump, two valves, a DC motor, which are connected to the shaft of the three‐phase induction motor. A sliding mode control system is used for position control of the DC motor for adjusting the valve angle for derating the induction motor. The authors present the results of an experiment in which a three‐phase induction motor was subjected to various unbalanced voltage conditions. The results of simulations were used to look into what happened when there were different levels of imbalanced voltage. This was done to determine how these situations changed an induction motor's speed, torque, and efficiency. For this system, the stator current would be greater than the rated current if there was an imbalance in the supply voltage. Therefore, to reduce the amount of power that the three‐phase induction motor can produce, the control system uses a DC motor to reduce the angle of one of the two valves. This decreasing angle continues until the root mean square value of the stator current returns to the rated current. At this point, the derating factor may be calculated by dividing the output power of the three‐phase induction motor in the unbalanced condition by the output power when there are ideal sinusoidal. The MATLAB SIMULINK environment is utilised to perform simulations of the proposed system. [ABSTRACT FROM AUTHOR]

The open‐circuit magnetic field of the V‐shaped interior PM (IPM) machine is predicted by the analytical method. The method is implemented following the basic principle of the subdomain method. The machine model is divided into five different regions, including rotor slot, magnetic barrier, air gap, stator slot, and stator slot opening. To perform the analytical prediction process in the polar coordinate system, these regions should be transformed into the appropriate subdomains. The last four regions can be transformed into the subdomains with the required shape based on the existing method. The rotor slot cannot be treated as a single subdomain, for the shape of which is irregular. Herein, the PM and vacuum region in the rotor slot is divided into several fan‐shaped subdomains. The division method is described clearly. Then, the boundary conditions alongside the interface between adjacent subdomains are derived based on function transformation. On this basis, the open‐circuit magnetic field of the IPM machine can be predicted. The magnetic field of the 6p/36 s V‐shaped IPM machine is obtained by the proposed method, finite element method simulation, and experiment, respectively. Additionally, the comparison results verify the accuracy and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

In the context of eccentric micro-scale Taylor–Couette flow, variations in localized flow scales result in a non-uniform fluid–solid interface slip state, distinct from the typically studied uniform slip velocity distribution. This study introduces a boundary condition definition method aimed at characterizing partial slip states, complemented by a coupled iterative analysis system tailored to address this complexity. Key contributions include the development of a method for calculating the limiting shear stress, which considers local velocity gradients and pressures. Validation demonstrates that the locally derived slip state aligns more closely with Knudsen number distributions of local flow scales compared to traditional uniform slip models, and exhibits greater consistency with experimentally measured pressure distributions. Additionally, the study reveals that eccentric Taylor–Couette flow, characterized by significant variations in local flow scales and strong self-induced pressure effects, leads to complex distributions of local pressure, velocity gradients, and differences in local slip velocities. Specifically, the non-uniform distribution of local pressure gradients due to eccentricity results in partial slip occurring predominantly on the rotor in regions with positive pressure gradients, and on the stator in regions with negative pressure gradients. Furthermore, the variation in gap height exerts a greater influence on local slip compared to rotational speed and eccentricity ratio. Under certain conditions influenced by pressure gradients, the slip velocity on the rotor may exceed its tangential speed. [ABSTRACT FROM AUTHOR]

The inlet and outlet radii are important design parameters that directly determine the internal/external characteristics and cavitation characteristics of the torque converter (TC). The stator and turbine are the main areas of cavitation in TCs. Based on this, the outlet radius of the stator and turbine is taken as the research object of this paper. In this study, computational fluid dynamics (CFD) models of different turbine and stator outlet radii are established, and the influence of stator/turbine outlet radius design parameters on the performance of TCs is revealed by comparing the internal/external characteristics and cavitation characteristics. The results show that reducing the outlet radius of the stator/increasing the outlet radius of the turbine will cause the stator and the turbine blade to be shorter, increase the area of the vaneless region between the impellers, and reduce the risk of cavitation in TCs. However, it will also lead to a decrease in the external characteristics of the low-speed ratio (SR) condition and an increase in the external characteristics of the high-SR condition. With the decrease in the stator outlet radius/the increase in the turbine outlet radius, the mass flow rate of TCs will decrease, and the mass flow loss caused by cavitation will decrease from the original 42.51 to 6.95 and 21.95 kg/s, respectively. The suppression rates of the stator/turbine outlet radius on TC cavitation volume are 58.894% and 52.359%, respectively. The research results of this study can provide practical engineering guidance for the design of high-performance TCs and cavitation suppression. [ABSTRACT FROM AUTHOR]

In vector-controlled Permanent Magnet Synchronous Motors (PMSMs), measuring the motor flux angle, particularly the rotor position, is essential. If a pulse error occurs during motor control using an encoder, it becomes impossible to accurately estimate the rotor position, leading to incorrect position angle information being used in the coordinate transformation. This mismatch causes discrepancies between the commanded three-phase stator current and the actual current applied to the motor. As a result, the motor and inverter output and efficiency decrease, and the control performance deteriorates. Therefore, research is necessary to compensate for such errors. This paper proposes an algorithm that detects pulse errors occurring in incremental encoders and automatically switches to the Hall sensor control mode to compensate for the encoder pulse errors. The proposed algorithm, based on Hall sensors, has the advantage of not significantly affecting control delays, which could be problematic in high-speed operating ranges; thus, effective control is maintained even in such situations. [ABSTRACT FROM AUTHOR]

FliL is a bacterial flagellar protein demonstrated to associate with, and regulate ion flow through, the stator complex in a diverse array of bacterial species. FliL is also implicated in additional functions such as stabilizing the flagellar rod, modulating rotor bias, sensing the surface, and regulating gene expression. How can one protein do so many things? Its location is paramount to understanding its numerous functions. This review will look at the evidence, attempt to resolve some conflicting findings, and offer new thoughts on FliL. [ABSTRACT FROM AUTHOR]

This paper proposes a method for the torque ripple reduction of an open-end winding interior permanent magnet synchronous motor (OEW-IPMSM) using direct self-control (DSC). The conventional DSC has been researched in high-power systems because of its advantages in terms of a low switching frequency and a fast response of torque. Nevertheless, high torque ripple is a disadvantage of the conventional DSC. This is because the trajectory of the stator flux is controlled in the shape of a hexagon for lower switching frequencies and by applying hysteresis torque control. In this paper, predictive torque control using a mathematical model of an OEW-IPMSM is presented to improve the quality of the torque control. In addition, the presented method addresses the trajectory control of the flux using the diverse voltage vectors of the dual inverter. The validity of the presented method is demonstrated by simulations and experimental results. [ABSTRACT FROM AUTHOR]

Soft-magnetic-composite (SMC) use in electric motors offers a significant growth opportunity to the PM industry. Barriers exist, however, that have prevented wide-scale adoption. Beyond the need for motor redesign, users need to understand the difference in performance and stated properties of SMCs and the dominant stator-core technology using lamination (electrical sheet) steels. Lamination steels used for stator cores have excellent magnetic properties within individual sheets. The comparison of these individual sheet properties, such as maximum saturation and permeability, with powder-based soft-magnetic-composite properties creates an unfavorable view of SMCs. The properties of lamination assemblies, however, are lower than individual sheets due to the stacking factor and the presence of insulation layers. Further, it is commonly understood that these stacks tend to work best at lower frequency, whereas SMCs are more suited to higher frequency. The number of direct comparisons of SMC and lamination steel stacks is limited in the literature, resulting in broad generalizations. In this study, test rings made with assemblies of 2 lamination steel grades and 2 grades of SMC have been evaluated under different test conditions. The effect of ring size and amount of lubricant are also discussed. The direct comparison between SMCs and lamination steel will enable users of the technology to understand the benefits and limitations of each approach, leading to the best engineering solutions. [ABSTRACT FROM AUTHOR]

Tandem bladed axial flow compressor concept has immense potential for increasing the stage loading over conventional stages. This infers significant improvement in gas turbine engine operational economics and performance. However, implementation of tandem configuration invites additional three dimensionalities in the flow field. This complicates the design process limiting the realization of the tandem bladed rotor concept. The present study addresses the strategies for development of a low-speed axial compressor design implementing tandem bladed rotor and single stator. Both the rotor and stator flow mechanisms have been investigated in detail using steady state simulations. A highly loaded tandem bladed rotor is followed by single bladed stator which handles the highly swirled flow. The single blade configuration of stator results in higher diffusion factor which is more susceptible to the flow separation. Moreover, a dual wake structure evolves through the rotor passage due to highly loaded individual blades. The stage design follows an unconventional approach of tandem rotor-single stator over the reported tandem rotor-tandem stator or only tandem bladed stator configuration. The aerodynamic match between the tandem bladed rotor and stator has been of critical importance in development of this design. The rotor has been designed for highest possible energization of flow by fine tuning the variation of tandem nozzle geometry throughout the span to complement the intended loading profile. The stator is aimed at letting the flow pass through with a chordwise varying diffusion profile. The novelty of the work lies in discussion of tandem rotor and single bladed stator flow physics altogether highlighting the interdependence of decision-making process for both. [ABSTRACT FROM AUTHOR]