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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]

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 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]

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]

The objective of this study is to evaluate the dependability of double-star induction machines by employing meticulous monitoring and intelligent handling of potential electrical malfunctions that may arise during their functioning. Specifically, the research delves into the examination of three distinct fault types: rotor bar breakage, stator phase opening, and inter-turn short circuit. Utilizing a mathematical model developed in the natural reference frame (abc), our aim is to comprehensively delineate both normal and faulty operational scenarios. To categorize and gauge the gravity of identified faults, we employ a methodology rooted in spectral analysis. In order to ensure continuous machine operation, especially in instances of stator phase opening, our proposed mitigation approach entails intentionally opening a secondary phase positioned at a 90-degree angle to the faulty phase. This strategic alteration transforms the machine into a dual two-phase configuration. Through rigorous simulation analyses, our findings underscore the efficacy and pragmatic viability of the devised fault detection technique, offering valuable insights into the domain of electrical machine reliability and fault management. [ABSTRACT FROM AUTHOR]

A Rotary-Pulsation Apparatus (RPA), also known in the literature as a Rotational Hydrodynamic Cavitation Reactor (RHCR), is a device which typically consists of a rotating mechanism that generates pulsations or vibrations within a fluid. This can be achieved through various means such as mechanical agitation, pneumatic pulses, or hydraulic forces. It is widely used in food, chemical, pharmaceutical, and microbiological industries to improve the mixing of different fluids, dispersion, pasteurization, and sterilization. In the present paper, a CFD study was conducted to develop and optimize the geometry of the RPA's rotor and stator to induce cavitation in the fluid flow. The effect of cavitation has the potential to improve dispersion and emulsion properties and to significantly reduce operation pressure, in comparison to conventional mixing systems. [ABSTRACT FROM AUTHOR]

Inverter-fed machines are widely used in electric vehicle drive systems and have shown a trend toward high voltage and frequency in recent years. They are subjected to multiple types of stress during operation, causing potential short-circuit fault damage to the stator winding insulation. Online condition monitoring of the insulation before or in the early stage of the short circuit fault can effectively reduce maintenance costs and ensure its health. This paper reviews and summarizes the deterioration mechanism and the recent online electrical monitoring techniques. First, four types of failure stress and each type's failure factors and mechanisms are analyzed. The coupling effect and overall process of multi-physical fields on stator insulation failure are considered. Secondly, the latest online electrical monitoring technologies are summarized. Each technique's principles, methods, advantages, and disadvantages are analyzed. Finally, existing problems and possible directions for improvement in current research are discussed, focusing on their feasibility and accuracy in practical applications. [ABSTRACT FROM AUTHOR]

This paper addresses performance degradation in nonlinear flux linkage algorithms, arising from estimation errors in rotor flux linkage due to fluctuations in current and temperature. We introduce a parameter-adaptive flux linkage model using MRAS, which dynamically adjusts the rotor flux linkage, significantly minimizing estimation errors and improving control performance. When the rotor flux linkage of the motor undergoes sudden changes, the nonlinear flux linkage model shows a speed fluctuation of 5%, whereas the parameter-adaptive flux linkage model reduces the error to 0.6%. The algorithm demonstrates strong robustness when the stator resistance undergoes a sudden change. The control effectiveness under conditions such as load start and load mutation is excellent. Simulations and experiments demonstrate that the parameter-adaptive flux linkage model improves the estimation accuracy of the rotor position when motor parameters change. [ABSTRACT FROM AUTHOR]

The flux switching permanent magnet (FSPM) motor is a stator permanent magnet motor. The typical FSPM motor is doubly salient, which generates torque ripple and affects the rotation smoothness. In this paper, the influence of salient pole geometric sizes on motor torque performance is studied to reduce motor torque ripple and improve motor torque density. First, three indicators are defined to present the motor torque characters, including the average torque, torque ripple, and the volume of permanent magnet material usage. Then, the model of salient pole geometric sizes function to the three indicators is created. With this model, the optimal solution is obtained by the multi-objective numerical optimization. Based on the optimized results, the rotor shape is refined and analyzed as the supplementary to reduce the torque ripple further. Finally, the results show that the optimization procedure in this paper can effectively weaken the torque ripple, reduce the permanent magnet material usage, and improve the average output torque of the motor. Based on the optimized data, the prototype machine is built to verify the analysis results and prove the feasibility of this research. [ABSTRACT FROM AUTHOR]

Flux reversal machine (FRM) belongs to the stator permanent magnet (PM) machine, which has the advantages of high reliability, high efficiency, and simple structure. However, large torque ripple and low torque density limit the development prospect of FRMs. Therefore, a wavy rotor FRM (WR-FRM) with curved stator slots is proposed, which can reduce the torque ripple while improving the average torque. The top surface of the rotor tooth consists of three sinusoidal functions, and the stator slots are constructed with a spline curve. To obtain better electromagnetic performance, the multi-objective genetic algorithm is used to optimize the FRM and the WR-FRM. Finally, the electromagnetic performances of the two machines is analyzed and compared by the finite element method. The results show that compared with the FRM, the torque generated by the unit volume of PM is increased by 36.47%, and the torque ripple is reduced by 62.7%. [ABSTRACT FROM AUTHOR]

Stator faults are one of the common issues in pumped storage generators, significantly impacting their performance and safety. To ensure the safe and stable operation of pumped storage generators, a stator fault diagnosis method based on an improved short-time Fourier transform (STFT)-support vector data description (SVDD) hybrid algorithm is proposed. This method establishes a fault model for inter-turn short circuits in the stator windings of pumped storage generators and analyzes the electrical and magnetic states associated with such faults. Based on the three-phase current signals observed during an inter-turn short circuit fault in the stator windings, the three-phase currents are first converted into two-phase currents using the principle of equal magnetic potential. Then, the STFT is applied to transform the time-domain signals of the stator's two-phase currents into frequency-domain signals, and the resulting fault current spectrum is input into the improved SVDD network for processing. This ultimately outputs the diagnosis result for inter-turn short circuit faults in the stator windings of the pumped storage generator. Experimental results demonstrate that this method can effectively distinguish between normal and faulty states in pumped storage generators, enabling the diagnosis of inter-turn short circuit faults in stator windings with low cross-entropy loss. Through analysis, under small data sample conditions, the accuracy of the proposed method in this paper can be improved by up to 7.2%. In the presence of strong noise interference, the fault diagnosis accuracy of the proposed method remains above 90%, and compared to conventional methods, the fault diagnosis accuracy can be improved by up to 6.9%. This demonstrates that the proposed method possesses excellent noise robustness and small sample learning ability, making it effective in complex, dynamic, and noisy environments. [ABSTRACT FROM AUTHOR]

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One of the major challenges of today’s rotating machine manufacturing industries is finding effective techniques to prevent early mechanical or electrical failure. Efficient troubleshooting methods must be developed for rotating electrical machines, such as three-phase and multiphase electrical induction or synchronous machines. A novel method for fault detection in a Wound Rotor Induction Machine (WRIM) is presented in this paper. Its originality lies in the determination of current rise and fall times in healthy and InterTurn short-Circuit Fault (ITSCF) cases. The method is based on using the two-current (isd, isq) sigmoid transform (ST) of Park’s vector approach. A WRIM with a nominal power of 0.3 kW is used for the analytical and experimental studies. The type of fault detection being studied is short circuit InterTurns on one phase of the stator winding. The results are promising because the methodology used is simple, fast, and accurate for diagnosing this type of fault, and can detect a low number of short-circuit InterTurns in the stator winding. [ABSTRACT FROM AUTHOR]

This study presents a comparative analysis of Direct Torque Control with Space Vector Modulation (DTC-SVM) and Finite Control Set Model Predictive Control (FCS-MPC) applied to five-phase induction motors. Five-phase induction motors offer enhanced performance, reliability, and efficiency over traditional three-phase motors, making them suitable for high-reliability applications. The performance of DTC-SVM and FCS-MPC is evaluated through experimental implementation on a 3.5 kW five-phase induction motor, focusing on both dynamic response during speed reference changes and load variations, and static response, under steady-state conditions, as well as energy quality, specifically stator voltage and current. Experimental results show that FCS-MPC provides superior dynamic response, effectively managing speed changes and load variations, while DTC-SVM, owing to its fixed switching frequency, excels at reducing torque ripple and minimizing stator current harmonics. The choice between DTC-SVM and FCS-MPC depends on the application's needs, weighing dynamic performance, torque stability, and harmonic content. This study provides valuable insights for optimizing five-phase induction motor control and encourages future research to refine these methods or develop hybrid approaches that combine their strengths. [ABSTRACT FROM AUTHOR]

The low specific speed centrifugal pump plays a crucial role in industrial applications, and ensuring its efficient and stable operation is extremely important for the safety of the whole system. The pump must operate with an extremely high head, an extremely low flow rate, and a very fast speed. The internal flow structure is complex and there is a strong interaction between dynamic and static components; consequently, the hydraulic excitation force produced becomes a significant factor that triggers abnormal vibrations in the pump. Therefore, this study focuses on a low specific speed centrifugal pump and uses a single-stage model pump to conduct PIV and pressure pulsation tests. The findings reveal that the PIV tests successfully captured the typical jet-wake structure at the outlet of the impeller, as well as the flow separation structure at the leading edge of the guide vanes and the suction surface. On the left side of the discharge pipe, large-scale flow separation and reverse flow happen as a result of the flow-through effect, producing a strong vortex zone. The flow field on the left side of the pressure chamber is relatively uniform, and the low-speed region on the suction surface of the guide vanes is reduced due to the reverse flow. The results of the pressure pulsation test showed that the energy of pressure pulsation in the flow passage of the guide vane occurs at the fBPF and its harmonics, and the interaction between the rotor and stator is significant. Under the same operating condition, the RMS value distribution and amplitude at fBPF of each measurement point are asymmetric in the circumferential direction. The amplitude of fBPF near the discharge pipe is lower, while the RMS value is higher. A complex flow structure is shown by the larger amplitude and RMS value of the fBPF on the left side of the pressure chamber. With the flow rate increasing, the energy at fBPF of each measurement point increases first and then decreases, while the RMS value decreases, indicating a more uniform flow field inside the pump. [ABSTRACT FROM AUTHOR]

In order to optimize the electromagnetic performance of a permanent magnet synchronous motor (PMSM) during operation, this paper takes the size of the stator slot structure of the motor as the optimization variable and the peak cogging torque and no-load back electromotive force (EMF) amplitude of the motor as the optimization objectives. A multi-objective optimization method based on the particle swarm optimization (PSO) algorithm is adopted to obtain a structural parameter combination that minimizes the peak cogging torque and no-load back EMF amplitude while meeting the reasonable range requirements of magnetic flux density amplitude. The optimized motor structure design prototype is experimentally verified. The results show that through multi-objective optimization based on the PSO algorithm, the electromagnetic performance of the motor has been improved, with a reduction of 36.33% in peak cogging torque and 2.65% in peak no-load back EMF, indicating a reasonable magnetic flux density amplitude. The experimental results of the optimized prototype show that the difference between the theoretical simulation values and the experimental values is within a reasonable range, which verifies the effectiveness of the multi-objective optimization method. [ABSTRACT FROM AUTHOR]

Three-phase induction motors play a key role in industrial operations. However, their failure can result in serious operational problems. This study focuses on the early identification of faults through the accurate diagnosis and classification of faults in three-phase induction motors using artificial intelligence techniques by analyzing current, temperature, and vibration signals. Experiments were conducted on a test bench, simulating real operating conditions, including stator phase unbalance, bearing damage, and shaft unbalance. To classify the faults, an Auto-Regressive Neural Network with Exogenous Inputs (NARX) was developed. The parameters of this network were determined through a process of selecting the best network by using the scanning method with multiple training and validation iterations with the introduction of new data. The results of these tests showed that the network exhibited excellent generalization across all evaluated situations, achieving the following accuracy rates: motor without fault = 94.2 %, unbalanced fault = 95%, bearings with fault = 98%, and stator with fault = 95%. [ABSTRACT FROM AUTHOR]

An inertial linear ultrasonic motor with a novel double-stator structure is proposed for achieving higher performance and resolution in this paper. Utilizing a symmetrical structure and single sawtooth wave signal, the prototype is capable of outputting effective linear motion based on inertial movement. The validity and rationality of the prototype are investigated by conducting finite element analyses. The experimental setups are built up to acquire the output characteristics of the motor. The experimental results indicate that the motor can achieve a maximum output velocity of 8.746 mm/s and thrust force of 1.645 N, which is almost twice the output performance of a motor with a single stator. The displacement solution of the motor can be adjusted by changing the amplitude of the voltage, with a resolution of 27 nm. Simultaneously, the relationships between the output characteristics and the input parameters are measured and analyzed during the experiments. Compared to the actuators with complex structures and multi-signal drives, the proposed motor exhibits the merits of higher output performance with the double-stator structure, providing an alternative direction for the further development of the inertial linear ultrasonic motor. [ABSTRACT FROM AUTHOR]

This study analyzes the turbomachinery flow of a gas turbine using OpenFOAM, an open-source CFD code. While foam-extend, a version of OpenFOAM, includes tools for turbomachinery analysis, some of its codes are incomplete, resulting in incorrect results. Consequently, this study required the investigation and correction of the solvers and libraries. Specifically, foam-extend-4.1 and a compressible multi-reference-frame solver were utilized. Two primary errors related to temperature calculation were identified. The first error involved temperature discontinuity at the interface between the stator and rotor domain when using the mixingPlane. The second error was related to temperature rising at the wall. To address the temperature discontinuity problem, the rothalpy jump equation in the enthalpyJump code was modified from a scalar product to an inner product of vectors. To resolve the high-temperature problem at the wall, modifications were made to the energy equation code in iEqn.H. A rothalpy separation was introduced, and the rothalpy equation was adjusted to mimic the enthalpy equation. The results obtained with the corrected codes were consistent with those from the commercial code, demonstrating the effectiveness of the modifications. [ABSTRACT FROM AUTHOR]

To ensure the reliable operation of asynchronous machine, the most effective is to use modern monitoring systems for current monitoring of the state of the main engine elements. This work presents research and developpment of a structural diagram of a modular unit for monitoring the appearance and development of the most frequent and difficult to diagnose types of defect to the main structural elements of the engine. The developed modular unit allows simultaneous monitoring of the presence of inter-turn short-circuits of the stator winding and the integrity of the structure of the short-circuited rotor winding. In the work of the monitoring unit Park's vector approach is used. When conducting research and developing algorithms for the operation of the modular unit, the possibility of accurately determining the degree of damage to the specified defects in the event of a violation of the quality of the engine power supply system was taken into account, which is very important for real-life conditions of use. The obtained results are ready for practical use in the development of new or improvement of existing monitoring systems for monitoring the condition of asynchronous machine under load with a possible poor-quality power supply system. [ABSTRACT FROM AUTHOR]

Conventional direct torque control (DTC) improves the dynamic performance of the five-phase induction machine (FPIM). Nevertheless, it suffers from significant drawbacks of high stator flux and electromagnetic torque ripples. Moreover, the DTC technique relies on an open-loop estimator for accurate stator flux module and position knowledge. However, this method is subjected to substandard performance, mainly during the low-speed operation range. Therefore, a sliding mode sensorless stator flux and rotor speed DTC based on an artificial neural network (DTC-ANN) for two parallel-connected FPIMs is discussed to tackle the problems above. This approach optimizes the DTC performance by replacing the two hysteresis controllers (HC) and the look-up table. As for the poor estimation drawback, the sliding mode observer (SMO) offers a robust estimation and reconstruction of the FPIM variables and eliminates the need for additional sensors, increasing the system's reliability. The present results verify and compare the performance of the control scheme [ABSTRACT FROM AUTHOR]

Compared with a traditional low‐speed high‐torque permanent magnet synchronous motor (PMSM), a permanent magnet (PM)/reluctance hybrid rotor dual‐stator synchronous motor (PM/RHRDSSM) has the advantages of high torque density and high space utilization. This type of motor is composed of a "back‐to‐back" PM + reluctance hybrid rotor and an inner and outer double stator. The number of poles of the inner and outer unit motors is the same, and the inner and outer stator windings are connected in series, driven by a single inverter. Due to the special mechanical structure and electromagnetic relationship of PM/RHRDSSM, traditional PMSM and synchronous reluctance motor maximum torque per ampere (MTPA) control strategies are no longer applicable. In response to this issue, the authors establishe a PM/RHRDSSM mathematical model of stator winding series structure and propose a MTPA control strategy suitable for this new type of motor. This strategy is aimed at the special mathematical model of PM/RHRDSSM and derives the analytical expression of MTPA trajectory, which minimises the required stator current amplitude of PM/RHRDSSM at various load torques, thereby minimising the motor copper loss. Finally, the effectiveness and practicality of the proposed control strategy were verified through simulation and experiments. [ABSTRACT FROM AUTHOR]

Vector-controlled drives require stator current information for use in current feedback and/or state variable estimators. That is why the detection and compensation of possible current sensor (CS) damage is so important. This article focuses on CS fault-tolerant control (FTC) in induction motor (IM) drive systems. In contrast to solutions known from the literature, two modified Luenberger observers (MLO) were applied, allowing for high-quality estimation of currents used in the detector and fault compensator. In a simple implementation of a detection algorithm based on residuals, an adaptive threshold coefficient was employed, enabling effective detection of various types of faults, regardless of whether the second CS was faulty or intact. The presented solution was evaluated during both motor and regenerative operation, with faults occurring in transient states, unlike solutions known in the literature. [ABSTRACT FROM AUTHOR]

In recent years, the use of permanent magnet synchronous motors has become popular. These engines are cheaper, lighter, and more durable. However, to control these motors, accurate information about the position of the rotor is necessary. For this reason, various methods have been used to improve the motor position estimation performance. One of these methods is estimation by injecting harmonic current into the stator winding. In this paper, using high-frequency currents injected into the stator, the rotor position in IPMSM motors is estimated. However, the response obtained has a DC offset due to the inaccuracy of the current measurement sensors, which causes an error in the estimation of the rotor position. The improved ePLL method was used to solve this problem. This method causes the convergence of the estimated position of the rotor to its real position by removing the noises of the current measurement circuit and the DC offset effect. The efficiency of this method has been proven first by simulation in MATLAB software, then in a Psim environment, and then implemented on the drive of a permanent magnet motor using a TMS320F28034 processor. [ABSTRACT FROM AUTHOR]

The axial gap structure of a half‐wave rectified variable field flux motor (AG‐HVFM) has been proposed, which has a double stator structure and field winding short‐circuited by a diode. Although the AG‐HVFM can achieve a high‐efficiency drive in wide speed and torque range via variable field flux control, its structure deteriorates the average torque and torque ripple. In this paper, we sequentially design the core shape, aspect ratio, and current control method for an AG‐HVFM to improve its torque characteristics. [ABSTRACT FROM AUTHOR]

To further improve the operating efficiency of linear induction motor, this paper proposes a loss minimization model predictive current control method based on governable loss online calculation. First, the method derives the equivalent circuit of linear induction motor containing independent iron loss branches, and establishes the loss model containing iron loss. Second, the expressions of stator d‐axis current with governable losses and secondary flux amplitude are derived from theoretical analysis, and then a given value of stator d‐axis current is derived when the governable losses are minimal. Then, a chain observer is designed to observe the secondary flux and calculate the governable loss and stator d‐axis current under the current operation. Finally, a method is proposed to introduce the stator d‐axis current observation results into the model predictive current control, which ensures the loss suppression effect and improves the dynamic performance at the same time. In addition, this article also compares the loss minimization controllers with or without iron loss. The simulation results are consistent with the theory, and the optimal control of the secondary flux of the linear induction motor can be successfully realized, thus effectively reducing the energy loss of the motor in the dynamic operation process. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Medium‐speed wind generators in the MW‐range with high‐temperature superconducting excitation winding are analyzed by means of non‐linear 2D and 3D FEM models. Besides an inverter‐based sinusoidal stator current feeding, a grid connection via a diode rectifier is analyzed by using coupled FEM and circuit simulations. The newly proposed modeling techniques are used to determine the excitation requirement for speed‐variable, unity power factor operation at constant stator voltage, as required for a diode rectifier feeding of the stator winding. 2D FEM models in the H‐A‐formulation are developed and used for the calculation of the hysteresis loss in the superconducting field winding at stationary operation as well as for an investigation of field current variations in the HTS field winding. The major modeling challenges consist in very long settling times of voltage‐fed models, several strong model non‐linearities and high requirements on the spatial discretization. Approaches for overcoming these difficulties with reasonable computational efficiency are proposed. [ABSTRACT FROM AUTHOR]

The uncontrollable angles (UAs) in direct torque control (DTC) algorithm is an important issue through which the effects of voltage vectors (VEs) on the magnetic flux and the torque are accurately determined. In this paper, a unique analysis of UAs is performed at different operating conditions, including parameters variations in two different strategies: Direct torque and stator flux control (DTC_SC) and (DTC_RC). Values of Those angles were accurately determined for wide speed, stator and rotor variations, and load changes. In addition, a detailed numerical comparison was performed in terms of these angles in the two strategies mentioned above for each operating condition. The comprehensive comparison showed the superiority of the DTC_RC strategy over its DTC_SC counterpart, being the maximum values of UAs in DTC_RC were 8°, 33°, and 21° versus 15°, 45°, and 38° in DTC_RC strategy for the following operations: Variable speed with variable stator resistance, variable speed with variable stator and rotor resistances, variable speed with variable load, respectively. MATLAB/Simulink results of the contributed analysis and comparisons were accomplished and validated. In addition, DS1103‐based experimental tests supported and verified the theoretical analysis. [ABSTRACT FROM AUTHOR]

We propose a magnetic-geared motor with controllable step-out torque. The operational principle which controls the step-out torque using DC currents is described. The controllable step-out torque characteristics are computed using finite element method. In addition, the load characteristics under vector control are also computed using finite element method. Two inherent characteristics are observed in this analysis result. One is that this magnetic-geared motor can generate the torque more than the step-out torque. The other is that the phase angle difference between the rotors when both rotors step out is around 30 deg. In this paper, the mechanism of these inherent characteristics is investigated by finite element method, and these inherent characteristics are verified by carrying out measurements on a prototype. [ABSTRACT FROM AUTHOR]

Numerical simulations of a shrouded stator cascade with an inter-stage cavity were conducted using validated numerical methods to investigate the impact of different labyrinth seal structures and positions on the aerodynamic performance of the stator cascade. The study discussed the development trends of secondary flow motion and corner separation within the cascade under different labyrinth seal structures, evaluated the stator performance using total pressure loss coefficient and entropy-based loss coefficient, and revealed the interaction between cavity leakage flow and mainstream flow. The results indicate that individually changing the labyrinth seal structure or position has a negligible impact on stator performance, but simultaneously altering both the structure and position of the labyrinth seal can effectively reduce stator losses. The structure case 1-position case 2 labyrinth seal structure can reduce total pressure loss by 6.25%, while structure case 4-position case 4 reduces entropy increase loss coefficient by 7.67%. Additionally, it was found that changing the labyrinth seal structure and position can increase the circumferential velocity and momentum of cavity leakage flow at the cavity outlet, enhance the resistance of cavity leakage flow to circumferential secondary flow within the stator passage, and reduce stator losses. Altering the structure and position of the labyrinth seal effectively reduces the cavity leakage vortex at the leading edge of the cascade during the mixing process of cavity leakage flow with the mainstream, causing the passage vortex to move rearward axially. [ABSTRACT FROM AUTHOR]

The steady and unsteady flow properties of the National Aeronautics and Space Administration (NASA) single-stage transonic compressor stage 35 are numerically investigated through the Reynolds-averaged Navier–Stokes (RANS) simulation method. The main purpose of the present paper is twofold. One is to validate the capability of the Spalart–Allmaras (S–A)-Helicity-γ model in unsteady RANS (URANS) simulation for rotor–stator interaction of a whole-stage compressor, and another is to figure out the roles played by helicity modification and transition augmentation in improving the performance of traditional S–A model. The results of steady RANS simulation indicate that the S–A model with helicity regulation is more sensitive to vortex structures in the end wall and blade-tip regions, while the inclusion of transitional intermittency factor can help predict the important transition phenomenon in the midspan region. As the back pressure increases, the inaccuracy of flow fields exchange caused by the mixing plane method becomes nonnegligible for the prediction of aerodynamic performance and thermodynamic quantities. Thus, URANS simulation seems to be necessary for more accurate prediction of the flow details of the stator subjected to periodic sweep of the rotor wake. On the suction surface of the stator, a turbulent separation bubble near the leading edge is transported downstream and merges into another separation bubble with much lower turbulence intensity at the trailing edge periodically. The combination of helicity and transition modifications provides advantages over traditional S–A model in describing this process, quite similar to its performance in steady simulations. [ABSTRACT FROM AUTHOR]

To comprehensively explore flow control method of profiled end wall for turbine stage at low Reynolds numbers, a surrogate model optimization platform including non-uniform rational B-spline surface parameterization method, support vector regression, and improved chaos particle swarm optimization algorithm is integrated. Optimization designs have been carried out for stator profiled end walls, rotor profiled end wall, and combined end walls, respectively. The results indicate that under the constraint of the output power, the application of various profiled end wall design cases all can effectively improve the aerodynamic performance of the turbine stage. By organizing the flow field of downstream rotor, the profiled end wall of stator can significantly affect the stage efficiency. The flow control benefits of the profiled end wall of the rotor is from the obstruction of the cross migration of the pressure side leg of the horseshoe vortex. The application of profiled end wall on stator has the most practical engineering value. Self-organizing maps and Shapley methods are used to explore potential correlation information of aerodynamic parameters and summarize design experience. The sensitive design variables of profiled end walls are extracted. Based on the local controllability of NURBS surfaces, the regions that affect the stage efficiency are mainly concentrated in the middle of the stator passage, near the stator trailing edge and near the rotor leading edge. The regions with a significant impact on the output power of the turbine stage are near the trailing edge of the rotor and stator. The corresponding design rules of end walls modeling are summarized. [ABSTRACT FROM AUTHOR]

Flow reversal in axial fans is usually carried out by changing the direction of rotation of the fan and rotating the stator vanes. The total pressure losses of selected inlet fan chambers were determined using CFD data for the normal and reverse flow conditions. These losses are 3.5 to 7.2 times greater for the normal flow increase due to the flow reversal in three chambers with the hub/tip ratio of 0.45 to 0.63. The operating points of two complete fans made up of the inlet chamber, the diffuser, and the axial stages A and B with different aerodynamic load were obtained using one-dimensional engineering calculation method. It uses the measured performance data relating to both fan stages. The calculated volumetric flow rate ratio for reverse and normal operation is 0.68 and 0.55, respectively, for the complete axial fan with the stages A and B. The acquired results are in accordance with the customers' requirements. [ABSTRACT FROM AUTHOR]

This study designs and builds a PLC application to optimize the dynamic braking process of a three-phase induction motor for safer and more efficient operation. The application monitors the motor braking system and calculates the braking time through a computer. The method used is experimental, aimed at designing a PLC application as a motor braking system utilizing the dynamic braking method. The braking system employs a PLC as the control system. To achieve dynamic braking, the stator coil of the motor receives an injection of direct current (DC) from a directed power source. The observed variables in this testing include the injected DC current value and the duration of the injection time. The test results demonstrate that the implementation of the PLC in the dynamic braking of a three-phase induction motor effectively calculates the motor braking time and monitors the braking process. In the dynamic braking test with a DC current injection of 0.5 A, an average stopping time of 2.63 seconds was recorded. With a DC current injection of 0.75 A, the average stopping time was 2.13 seconds. At a DC current injection of 1 A, the average stopping time decreased to 1.83 seconds, and at 1.2 A, it further decreased to 1.63 seconds. These results indicate that the motor stopping time is influenced by the magnitude of the injected current, with higher currents resulting in shorter stopping times. [ABSTRACT FROM AUTHOR]

Rotor bar breakage in induction motors is often detected by analysing the signatures in the stator current. However, due to the alteration of the current spectrum, traditional methods may fail when inverter-fed motors operate with closed-loop control using a cascade structure to regulate the speed. In this paper, the potential of zero-sequence voltage analysis to detect this fault is investigated, and a new index to quantify the severity of the fault based on this signal is proposed. Signals from motors operating under different control strategies and signals from motors powered from the mains are considered to verify the robustness of the proposed fault severity index. As a result, in all the analysed conditions the value of the proposed index for the healthy motor is found to be approximately 0.010, while for the faulty machine it is between 0.110 and 0.252. [ABSTRACT FROM AUTHOR]

Purpose. To obtain analytical dependencies for the precise calculation of the stator current of a frequency-regulated three-phase shortcircuited induction motor and to estimate the components of its main electrical power losses, which are spent on the transportation magnetic power losses (to the magnetization circuit) and additional power losses (through the motor air gap), as well as with using the obtained refined dependencies to research the electromagnetic processes and energy modes of the frequency-regulated induction motor when its speed and load change. Methodology. The method of generalized vectors is used for the refined calculation of the electromagnetic processes and energy modes of the frequency-regulated induction motor. Results. Based on the catalog data and parameters of the induction motor’s equivalent replacement circuit, also the specified values of its useful rotational torque and speed, refined analytical dependencies were obtained for the calculation of the main electromagnetic power losses of the frequency-regulated induction motor, which take into account the influence of all types of power losses, which present in it, as well as – power losses spent on transporting magnetic losses (to the magnetization circuit) and additional losses (through the air gap of the motor). With the help of the obtained dependencies, the energy modes (including main power consumption and electromagnetic power losses, efficiency factor, power factor) of the frequency-regulated induction motor in the driving and generator modes of its operation in relation to the first (at speeds not higher than the nominal) and the second (at speeds above the nominal) speed control zones for the operating ranges of the motor useful rotational torque and speed changes were calculated. Originality. A refined analytical calculation dependence has been obtained for determining the active projection of the generalized stator current vector of a frequency-regulated induction motor, which takes into account the presence of additional power losses and the component of electrical losses caused by the transportation of additional power losses through the air gap of the motor; an analytical dependence is also proposed for determining the increment of the mentioned active projection, which is due to the transportation of magnetic power losses to the motor magnetization circuit. Practical value. Analytical calculation dependencies are proposed for the quantitative assessment of errors (as a percentage of mentioned values) in steady-state modes for determining the main electromagnetic power losses of the frequency-regulated induction motor, caused by the absence (in comparison with relevant studies from known publications) of taking into account additional and magnetic power losses, as well as – the influence of electrical component losses caused by the transportation of the mentioned power losses through the air gap or to the magnetization circuit of the motor, respectively. References 16, tables 5, figures 2. [ABSTRACT FROM AUTHOR]

During the operation of a reversible pump-turbine, a hump area can easily appear under the pump condition, which will greatly affect the performance of a storage unit, with pressure pulsation being the key factor for the stable operation of a pump-turbine. Therefore, in order to explore the pressure pulsation characteristics of each flow component in the hump area, this paper first compared the full characteristics of the model test under different working conditions, and then it analyzed the pressure pulsation characteristics. By analyzing the pressure pulsation characteristics in the unit's flow component under different flow rates in the hump area, the pulsation rule of a pump-turbine running in the hump area was revealed. It was found that the peak-to-peak value of the draft tube in the hump area was the smallest under the optimal flow condition, and the peak-to-peak value increased along the flow direction, with the rotor and stator interaction (RSI) effects being continuously enhanced. When away from the runner basin, the influence of RSI gradually weakened after leaving the runner. No low frequency was found in the optimal traffic. The peak-to-peak value of the low flow condition increased compared with the optimal flow condition, and the distribution was not uniform. The main frequency of the whole basin was relatively complex, indicating that the flow of water was unstable in the condition of partial load, resulting in the hump area during the unit operation. The research results can provide a theoretical reference for improving the stability of pump-turbines. [ABSTRACT FROM AUTHOR]

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

There are numerous methods for detecting interturn faults (ITFs) in the field winding of synchronous machines (SMs). One effective approach is based on comparing theoretical and measured excitation currents. This method is unaffected by rotor temperature in static excitation SMs. However, this paper investigates the influence of rotor temperature in brushless synchronous machines (BSMs), where rotor temperature significantly impacts the exciter excitation current. Extensive experimental tests were conducted on a special BSM with measurable rotor temperature. Given the challenges of measuring rotor temperature in industrial machines, this paper explores the feasibility of using stator temperature in the exciter field current estimation model. The theoretical exciter field current is calculated using a deep neural network (DNN), which incorporates electrical brushless synchronous generator output values and stator temperature, and it is subsequently compared with the measured exciter field current. This method achieves an error rate below 0.5% under healthy conditions, demonstrating its potential for simple implementation in industrial BSMs for ITF detection. [ABSTRACT FROM AUTHOR]

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

The electromechanical effect of rotor pole numbers on machine output parameters such as flux linkage, induced-voltage, torque, power and demagnetization of a double stator permanent magnet machine is presented in this study. The investigation is carried out through the application of MAXWELL-2D finite element software. The study revealed that the machine topology that has 11 rotor poles would have higher flux linkage, inducedelectromotive force, torque and power amplitudes compared with other analyzed machine types. Nevertheless, the machine type that has 14-rotor poles would have the largest output torque, if the machine types are subjected to the same amount of permanent magnet material or volume. Also, the 14-pole machine type has the widest-speed coverage, an excellent quality for traction and vehicle applications. Similarly, the results revealed that the compared machine topologies have good capability against demagnetization effects. The largest shaft torque produced in the 10-pole, 11-pole, 13-pole and 14-pole machine types is 1.37 Nm, 2.44 Nm, 2.28 Nm and 1.47 Nm, respectively. [ABSTRACT FROM AUTHOR]

This paper reports the design, fabrication, and characterization of a MEMS capacitive accelerometer with an asymmetrical comb finger arrangement. By optimizing the ratio of the gaps of a rotor finger to its two adjacent stator fingers, the sensitivity of the accelerometer is maximized for the same comb finger area. With the fingers' length, width, and depth at 120 μm, 4 μm, and 45 μm, respectively, the optimized finger gap ratio is 2.5. The area of the proof mass is 750 μm × 560 μm, which leads to a theoretical thermomechanical noise of 9 μg/√Hz. The accelerometer has been fabricated using a modified silicon-on-glass (SOG) process, in which a groove is pre-etched into the glass to hold the metal electrode. This SOG process greatly improves the silicon-to-glass bonding yield. The measurement results show that the resonant frequency of the accelerometer is about 2.05 kHz, the noise floor is 28 μg/√Hz, and the nonlinearity is less than 0.5%. [ABSTRACT FROM AUTHOR]

To improve torque characteristics, this study proposes an upgrade over the standard salient pole stator in a Permanent Magnet Synchronous Motor (PMSM) using a segmented stator. The rotor is externally oriented and has a permanent magnet (PM) incorporated in it. The structure is studied theoretically through flux linkage analysis, torque production, and magnetic circuit model (MCM) analysis. Next, the finite element technique (FEM) is used to model the suggested motor and the salient pole stator, both of which have the same size. Next, a comparison is made between the simulation findings and the static torque, PM demagnetization, flux linkage, magnetic flux density distribution, and average and maximum torque. The proposed design results in a 79.97% increase in average torque, a 90.89% increase in maximum torque, and a 3.02% decrease in cogging torque. [ABSTRACT FROM AUTHOR]

Condition monitoring plays a pivotal role in safeguarding three‐phase induction motors (IMs) commonly utilized in industrial and commercial settings. This study focuses on wound rotor induction motors (WRIMs), specifically addressing the adverse impact of the stator and rotor winding inter‐turn short circuits. Unlike prevalent literature concentrating on squirrel cage induction motors (SCIMs) and emphasizing stator inter‐turn and broken rotor bar faults, this paper introduces a comprehensive technique applicable to detecting inter‐turn faults (ITFs) in WRIMs. The proposed method ensures stable motor operation and averts catastrophic failures.Experimental validation is conducted on a three‐phase, 7.5 hp, 415 V WRIM, affirming the technique's effectiveness under conditions of unbalanced source voltages and asymmetries in stator and rotor windings. The approach employs motor currents‐based experimental emulation, utilizing loci of instantaneous symmetrical components of three‐phase stator currents, £ (is1 – is2) and rotor currents £ (ir1 – ir2) for stator and rotor ITFs detection, respectively. Termed the ‘Wing Technique’ (WT), this method derives its name from the distinctive ‘Wing Shape’ formed by these loci. [ABSTRACT FROM AUTHOR]