Search Results (1,332)

This paper proposes a novel direct-drive rotary actuator based on a modular five-phase outer-rotor flux-switching permanent magnet (FSPM) machine to overcome the limitations of conventional actuators with gear reducers, such as mechanical complexity and low reliability. The research focused on a synergistic design of a lightweight, high-torque-density motor and a precise control strategy. The methodology involved a structured topology evolution to create a modular stator architecture, followed by finite element analysis-based electromagnetic optimization. To achieve precision control, a multi-vector model predictive current control (MPCC) scheme was developed. This optimization process contributed to a significant performance improvement, increasing the average torque to 13.33 Nm, reducing torque ripple from 9.81% to 2.36% and obtaining a maximum position error under 1 mil. The key result was experimentally validated using an 8 kg inertial load, confirming the actuator’s feasibility for industrial deployment. Full article

Hybrid marine energy platforms that integrate wave energy converters (WECs) and hydrokinetic turbines (HKTs) offer potential to improve energy yield and system stability in marine environments. This study identifies a compatible WEC–HKT integrated system concept through a structured concept selection framework based on multi-criteria decision analysis (MCDA). The framework follows a two-stage process: individual technology assessment using eight criteria (efficiency, TRL, self-starting capability, structural simplicity, integration feasibility, environmental adaptability, installation complexity, and indicative cost) and pairing evaluation using five integration-focused criteria (structural compatibility, PTO feasibility, mooring synergy, co-location feasibility, and control compatibility). Criterion weights were assigned through a four-level importance framework based on expert judgment from 11 specialists, with unequal weights for the individual evaluation and equal weights for the integration stage. Four WEC types (oscillating water column, point absorber, overtopping wave energy converter, and oscillating wave surge converter) and four HKT types (Darrieus, Gorlov, Savonius, and hybrid Savonius–Darrieus rotor) are assessed using literature-derived scoring and weighted ranking. The results show that the oscillating water column achieved the highest weighted score among the WECs with 4.05, slightly ahead of the point absorber, which scored 3.85. For the HKTs, the Savonius rotor led with a score of 4.05, surpassing the hybrid Savonius–Darrieus rotor, which obtained 3.50, by 0.55 points. In the pairing stage, the OWC–Savonius configuration achieved the highest integration score of 4.2, surpassing the PA–Savonius combination, which scored 3.4, by 0.8 points. This combination demonstrates favorable structural layout, PTO independence, and mooring simplicity, making it the most promising option for early-stage hybrid platform development. Full article

Interior Permanent Magnet Synchronous Motors (IPMSMs) are widely used in the electrification sector; however, reliance on rare-earth magnets imposes constraints stemming from supply instability and mining-related environmental impacts, raising sustainability concerns. To address these issues, this study investigates an IPMSM employing a consequent pole (CP) structure, in which one permanent magnet pole is replaced by iron. Because flux asymmetry in CP IPMSMs can cause torque ripple and associated vibration and noise, we propose an Intersect Consequent Pole (ICP) rotor geometry and evaluate it against a conventional IPMSM under identical stator conditions. The proposed ICP topology reduces permanent magnet usage and provides a rare-earth-reduced design alternative that addresses the vibration/noise trade-off, with a particular focus on electric power steering (EPS) applications. Electromagnetic characteristics and performance were analyzed using finite element analysis (FEA) and verified via FEA-based comparisons. Full article

Wind power is integral to the transformation of energy systems towards sustainability. However, the increasing number of wind turbines approaching the end of their service life presents significant challenges in terms of waste management and environmental sustainability. Rotor blades, typically composed of thermoset polymer composites reinforced with glass or carbon fibres, are particularly problematic due to their low recyclability and complex material structure. The aim of this article is to provide a system-level review of current end-of-life strategies for wind turbine components, with particular emphasis on blade recycling and decision-oriented comparison, and its integration into circular economy frameworks. The paper explores three main pathways: operational life extension through predictive maintenance and design optimisation; upcycling and second-life applications; and advanced recycling techniques, including mechanical, thermal, and chemical methods, and reports qualitative/quantitative indicators together with an indicative Technology Readiness Level (TRL). Recent innovations, such as solvolysis, microwave-assisted pyrolysis, and supercritical fluid treatment, offer promising recovery rates but face technological and economic as well as environmental compliance limitations. In parallel, the review considers deployment maturity and economics, including an indicative mapping of cost and deployment status to support decision-making. Simultaneously, reuse applications in the construction and infrastructure sectors—such as concrete additives or repurposed structural elements—demonstrate viable low-energy alternatives to full material recovery, although regulatory barriers remain. The study also highlights the importance of systemic approaches, including Extended Producer Responsibility (EPR), Digital Product Passports and EU-aligned policy/finance instruments, and cross-sectoral collaboration. These instruments are essential for enhancing material traceability and fostering industrial symbiosis. In conclusion, there is no universal solution for wind turbine blade recycling. Effective integration of circular principles will require tailored strategies, interdisciplinary research, and bankable policy support. Addressing these challenges is crucial for minimising the environmental footprint of the wind energy sector. Full article

The air turbine starter (ATS) of an aero-engine incorporates a high-speed, high-energy rotor. An uncontained failure of the ATS could lead to catastrophic consequences, making containment capability research critically important. This study proposes a comprehensive evaluation methodology for ATS containment. A full-scale finite element model of the whole structure of an ATS was established to analyze containment characteristics and structural deformation patterns. Furthermore, an experimental method for ATS containment testing was designed to investigate the containment process and critical structural damage. By integrating simulation and experimental results, the load transfer paths and structural dynamic response of the ATS were systematically analyzed. The results demonstrate that sudden high-energy loads primarily follow two distinct transfer paths, each causing completely different structural damage behaviors. After the turbine wheel is broken, the resulting unbalanced load causes turbine shaft oscillation, which, in turn, compresses the bearings and damages their inner and outer rings. This research provides valuable guidance for the structural design of air turbine starters. Full article

Magnetically levitated artificial hearts impose stringent requirements on the blood-pump motor: zero friction, minimal heat generation and full biocompatibility. Traditional mechanical-bearing motors and permanent-magnet bearingless motors fail to satisfy all of these demands simultaneously. A bearingless switched reluctance motor (BSRM), whose rotor contains no permanent magnets, offers a simple structure, high thermal tolerance, and inherent fault-tolerance, making it an ideal drive for implantable circulatory support. This paper proposes an 18/15/6-pole dual-stator BSRM (DSBSRM) that spatially separates the torque and levitation flux paths, enabling independent, high-precision control of both functions. To suppress torque ripple induced by pulsatile blood flow, a variable-overlap TSF-PWM-DITC strategy is developed that optimizes commutation angles online. In addition, a grey-wolf-optimized fast non-singular terminal sliding-mode controller (NRLTSMC) is introduced to shorten rotor displacement–error convergence time and to enhance suspension robustness against hydraulic disturbances. Co-simulation results under typical artificial heart operating conditions show noticeable reductions in torque ripple and speed fluctuation, as well as smaller rotor radial positioning error, validating the proposed motor and control scheme as a high-performance, biocompatible, and reliable drive solution for next-generation magnetically levitated artificial hearts. Full article

Efficient prediction of aerodynamic loads on wind turbine blades under yawed inflow remains challenging due to the complexity of three-dimensional unsteady flow phenomena. In this work, a modified blade element momentum (BEM) method, incorporating multiple correction models, is systematically compared with high-fidelity computational fluid dynamics (CFD) simulations for the NREL Phase VI wind turbine across a range of inflow velocities (7–15 m/s) and yaw angles ($0^{°}$–${60}^{°}$). A normalized absolute error metric, referenced to experimental measurements, is employed to quantify prediction discrepancies at different yaw conditions, wind speeds, and spanwise blade locations. Results indicate that the corrected BEM method maintains good agreement with measurements under non-yawed attached flow, with errors within 2%, but its accuracy declines substantially in separated and yawed flow regimes, where errors can exceed 20% at high yaw angles (e.g., ${60}^{°}$) and low tip-speed ratios. CFD flow-field visualizations, including vorticity and Q-criterion iso-surfaces, reveal that yawed inflow strengthens vortex interactions on the leeward side and generates Coriolis-driven spanwise vortex structures, promoting stall progression from tip to root. These unsteady phenomena induce load fluctuations that are not captured by steady-state BEM formulations. Based on these insights, future studies could incorporate vortex structure and spanwise flow features extracted from CFD into unsteady correction models for BEM, enhancing prediction robustness under complex operating conditions. Full article

Within the field of permanent magnet synchronous motor sensorless speed control systems, we present a novel scheme with a Multi-dimensional Taylor Network (MTN)-based nonlinear observer as the core, supplemented by two auxiliary MTN modules to realize closed-loop control: (1) MTN Model Identifier: Provides real-time PMSM nonlinear dynamic feedback for the observer; (2) MTN Adaptive Inverse Controller: Compensates for load disturbances using the observer’s estimated states. The study focuses on optimizing the MTN observer to address key limitations of existing methods (high computational complexity, lack of stability guarantees, and low estimation accuracy). Compared with the neural network observer, this MTN-based scheme stands out due to its straightforward structure and significantly reduced approximately 40% computational complexity. Specifically, the intricate calculations and high resource consumption typically associated with neural network observers are circumvented. Subsequently, by leveraging Lyapunov theory, an adaptive learning rule for the MTN weights is meticulously devised, which seamlessly bridges the theoretical proof of the nonlinear observer’s stability. Simulation results demonstrate that the proposed MTN observer achieves rapid convergence of speed and position estimation errors (with steady-state errors within ±0.5% of the rated speed and ±0.02 rad for rotor position) after a transient period of less than 0.2 s. Even when stator resistance is increased by tenfold to simulate parameter variations, the observer maintains high estimation accuracy, with speed and position errors increasing by no more than 1.2% and 0.05 rad, respectively, showcasing strong robustness. These results collectively confirm the efficacy and practical value of the proposed scheme in PMSM sensorless speed control. Full article

The traditional vertical-shaft-impact sand-making machine has the problems of uneven discharge particles and discharge port wear. To solve these problems, the influence of the main structural parameters (number of impact rotors, angle of impact plates, angle of anvil, and number of teeth on the anvil) on sand production is researched through orthogonal testing and polar analysis. The results show that the parameters’ degrees of influence on the sand production rate are as follows: the angle of impact plates, the number of impact plates, the angle of the anvil, and the number of teeth on the anvil. The double rotor exhibits the best crushing effect when the number of impact rotors is six, the angle of the impact plate is 0°, the angle of the anvil plate is 0°, and the number of teeth on the anvil plate is 89. By taking the working speed of the double rotors as a factor, an equal-level uniform design table is constructed for the double-rotor crushing system. Polynomial regression analysis shows that the best crushing effect occurs when the accelerating rotor speed is 1200 r/min and the impact rotor speed is 585 r/min. Finally, the crushing characteristics of the double-rotor vertical-shaft-impact sand-making machine are simulated and analyzed to obtain the kinetic energy distribution of particles in the crushing chamber. The kinetic energy of particles in the main crushing area is determined, and the wear pattern of the discharge port and parts is identified. Full article

This study proposes a novel variable-radius arc rotor, developed based on the conventional arc rotor, for application in a hydrogen circulation pump. Numerical simulations are conducted to analyze and compare the flow characteristics of the optimized rotor with those of the baseline rotor. Results show that the optimized rotor increases outlet mass flow rates by over 15%; however, it has little effect on pressure pulsation, indicating limited influence on flow stability. Flow field analysis reveals that the optimized rotor promotes a more stable and streamlined internal velocity distribution, suppressing localized disturbances and vortices that are prevalent with the baseline rotor. Furthermore, assessments of turbulent kinetic energy (TKE) and three-dimensional vortex structures show that the optimized rotor confines high-energy zones to essential areas and facilitates controlled vortex evolution. These effects collectively lead to lower turbulence intensity, reduced energy loss, improved operational efficiency, and enhanced mechanical reliability of the pump. Full article

In this study, a sensorless speed control method is proposed to enhance the speed control performance under load variations by utilizing a discrete-time flux observer in a V/f control environment. Due to their simple structure, low cost, and high reliability, induction motors are widely used in various fields, such as fans, pumps, and home appliances. Among the control methods for induction motors, V/f control operates as an open-loop system, without using speed sensors. It is mainly applied in industrial environments where fast dynamic performance is not required, due to its simple implementation and low cost. However, in cases of load variations or low-speed operation, it suffers from performance degradation and control limitations due to flux variations. To overcome these issues, this paper proposes a method that uses a discrete-time flux observer to estimate the stator flux. We calculate the rotor speed based on the estimated flux, and then improve V/f control performance by adding a compensation signal to the reference frequency, which signal is generated through a PI controller based on the difference between the estimated rotor speed and the reference speed. The proposed method is validated through MATLAB/Simulink-based simulations and experiments using a 5.5 kW induction motor M−G set, confirming that compared to conventional V/f control, the speed maintenance capability and overall robustness against load variations are enhanced. This study presents a practical solution to effectively improve the performance of existing V/f control systems without adding external sensors. Full article

In the tail rotor transmission system of a high-speed helicopter, the timely supply of lubricating oil to the wet friction clutch during frequent starts and stops has a significant impact on the performance of the transmission system. The oil flow requirements of clutches vary across different operational stages, posing a challenge for traditional centrifugal oil supply methods to meet the demand for flow regulation under such dynamic conditions. This paper proposes a novel two-stage centrifugal oil supply structure capable of achieving superior flow control during various clutch operating phases. An experimentally validated two-phase oil–gas CFD model was established to analyze the effects of operational parameters, such as rotational speed and oil supply pressure difference, as well as structural parameters, on oil supply performance. To enhance oil supply flow rate and efficiency under high-speed conditions (rated speed of 4800 rpm and 85% speed) at a common supply pressure (0.45 MPa), while reducing the pressure at the input shaft interface, key structural parameters were determined and optimized using a combined approach of Taguchi orthogonal experiments and response surface methodology. The results demonstrate that the optimized structure achieves a 142.8% increase in the weighted oil supply flow rate, an 11.1% improvement in oil supply efficiency, and a 7.5% reduction in pressure at the input shaft interface. Full article

This study investigates the behavior of large-scale wind turbines operating under high wind speed conditions. A particular emphasis is placed on power output limitations and the dynamic adjustment of rotor blade pitch angles to ensure system stability and prevent structural or operational damage. The novelty of this work lies in integrating real operational data with simplified empirical models, C_P(ω) and P_WT(β, V), to identify an energy-efficient operating zone that minimizes curtailment losses. Using experimental data from a 2.5 MW wind turbine located in the Dobrogea region of Romania, the power curves and mechanical behavior under variable pitch control were analyzed. At a wind speed of 16.5 m/s, the theoretical available power exceeded 12 MW, while the measured output was curtailed to 2.52 MW, corresponding to an ≈80% loss due to pitch regulation. The recalculated power coefficient C_P decreased from ≈0.48 at V = 10 m/s to ≈0.28 at V = 16.5 m/s. Polynomial fitting achieved R² = 0.982 and RMSE = 0.014, ensuring accurate representation of experimental data. Results demonstrate significant losses in extractable wind power when the turbine is operated in a curtailed mode due to pitch regulation. Strategies for maintaining maximum power point (MPP) operation are discussed, along with potential implications of coupling turbines with energy storage systems to reduce curtailment effects. The findings contribute to improved wind turbine control strategies in variable and extreme wind environments. The theoretical models developed in this study were validated using real-world data recorded from a GEWE-B2.5-100 wind turbine located in Dobrogea, Romania. Full article

Severe pressure pulsations caused by complex flow fields in pumped-storage power stations significantly threaten operational safety and stability. With advances in computational technology, fully three-dimensional simulations coupling pipelines and pump-turbine units have become feasible. In this study, a fully three-dimensional analysis model was developed, coupling the water conveyance system and a finely modeled prototype-scale pump-turbine with splitter blades, to numerically simulate the compressible flow field under the maximum head pump mode. The study reveals a strong bidirectional coupling between the flow in the long outlet pipe and the internal flow within the pump-turbine unit. Influenced by structural features such as bifurcations and flow impingement at the T-junction, complex three-dimensional vortices arise and cannot be neglected. Based on the flow field, the study further investigates the time-domain, frequency-domain, and spatial characteristics of pressure pulsations at various downstream hydraulic components, ranging from the vaneless space to the outlet of the long outlet pipe. The pressure pulsation frequencies are shown to be affected by both rotor–stator interactions and the complex vortical structures in the flow. These findings clearly demonstrate the necessity of fully three-dimensional simulations that incorporate both the water conveyance system and the pump-turbine unit. Full article

With the growing demand for high-efficiency and high-performance electric motors in applications such as electric vehicles, drones, and industrial drive systems, Axial Flux Motors (AFMs) have gained significant attention due to their high torque density and compact structure. However, low-pole AFMs are prone to performance degradation and noise issues caused by magnetic saturation in the rotor back yoke and increased torque ripple. In this study, a conventional 6-pole, 9-slot Radial Flux Motor (RFM) was redesigned as an AFM within the same external volume. To minimize losses, the stator inner diameter and slot thickness were co-optimized. In addition, tapering techniques were applied to both the stator and magnets to reduce torque ripple, and a parametric analysis of magnet tapering was conducted to identify optimal design conditions. A rolling core fabrication method was adopted to ensure both electromagnetic performance and manufacturability. The final AFM design demonstrated a 1.4 percentage point improvement in efficiency. Additionally, torque ripple was reduced by 69.44%, thereby validating the effectiveness of the AFM redesign and ripple reduction strategy. Full article