Structural design and mechanical performance analysis of dual-stator brushless doubly-fed generator

Magnitude-phase equivalent circuit and steady-state power-angle characteristic analysis of DFIG

This paper presents an analysis and control design of a doubly-fed induction generator (DFIG)-based wind generation system operating under unbalanced network conditions. A DFIG system model in the positive and negative synchronous reference frames is presented. Variations of stator active and reactive powers and generator torque are fully defined in the presence of negative sequence voltage and current. Alternative DFIG control targets during network unbalance, such as reducing stator current unbalance, torque, and power pulsations minimization, are identified. A rotor current control strategy based on positive and negative (dq) reference frames is used to provide precise control of the rotor positive and negative sequence currents. Simulation results using EMTDC/PSCAD are presented for a 2-MW DFIG wind generation system. It shows that conventional vector control of DFIG without considering network unbalance results in excessive oscillations on the stator active/reactive power, electromagnetic torque, and stator/rotor currents even with a small stator voltage unbalance. In contrast, with the proposed control strategy, enhanced system control and operation such as minimizing oscillations in either active power, or electromagnetic torque, or stator or rotor currents can be achieved

In order to meet the requirements of high precision and rigidity of the two-dimensional turntable, it is necessary to carry out the structural design and position accuracy analysis of the two-dimensional turntable. The study found that the structure of the turntable, the resistance torque, the shaft structure, and the selection and design of the motor and sensor are all key factors affecting the performance of the two-dimensional turntable. In this paper, a method for structural design and simulation of a two-dimensional space turntable is proposed. In the process of structural design, these key factors are analyzed in detail, and the statics, modal and dynamic simulation analysis of the two-dimensional turntable are carried out using ANSYS Workbench software. Through simulation analysis, various indicators of the turntable are checked. Finally, it is concluded that the simulation results fully meet the requirements of the design indicators, which verifies the rationality of the design method and provides a strong basis for the structural design of the two-dimensional space turntable.

Due to surface-mounted permanent magnet (PM) high speed synchronous machines need a glass or carbon-fiber bandage to fasten the magnets to the rotor surface, which increase equivalent air-gap length and decreases efficiency of heat dissipation, so a claw pole motor with outer PM rotor is presented, which is without bandage. The design process of this motor for high speed application is introduced, and the method of structure design is analyzed, then a 5kW 40000r/min claw pole motor with outer PM rotor is designed. Finally the finite element calculation of magnetic field and dynamics analysis of outer rotor are finished, so the results of stress and modal analysis verify the feasibility of this machine.

In order to solve the problem that a traditional articulated arm coordinate measuring machine (AACMM) cannot measure automatically, a self-driven AACMM is proposed. Based on the self-driven AACMM design indicators, the length of the connecting rods of the self-driven AACMM was allocated. The self-driven AACMM virtual prototype was designed and assembled based on joint module selection and joint component design, and its measurement space range was also verified. The key components of the structural optimized design and dynamic performance analysis of motion parameters are adopted, respectively, to correct the positioning error of the self-driven AACMM’s probe caused by static and dynamic deformations. The static deformation of the structure caused by the self-driven AACMM’s weight was analyzed. The influence of the dynamic flexible deformation on the positioning error of the probe of the self-driven AACMM during the variable-speed approach and the constant-speed touch measurement stage was studied. The results show that the measurement space range of the self-driven AACMM designed in this paper can meet the design index of the measuring radius. The probe position error caused by static deformation of the measuring machine after structural optimization is reduced by an order of magnitude, and the equivalent stress of the mechanical structure of the self-driven AACMM is within the allowable stress of the material. The positioning error of the probe caused by the dynamic deformation of the self-driven AACMM structure meets the positioning accuracy index. During the stage of self-driven AACMM constant-speed touch measurement, the instantaneous position error of the probe changes linearly with the touch time and the optimal touch speed (6.6 mm s−1, 6.4 mm s−1) exists to minimize the probe positioning error. During the variable-speed approach stage, the influence of the angular acceleration and the angular velocity of each joint on the positioning error of the probe is negligible when the self-driven AACMM is in the typical posture. In the extreme posture, with the optimal joint angular acceleration ( 0.00055∘s−2 ) and angular velocity ( 0.0185∘s−1 ), the inertial force of the measuring machine structure and the instantaneous position error of the probe are the smallest, and the movement stability is the best. The structural optimization design and motion parameter performance analyses of the self-driven AACMM can provide a theoretical research foundation for subsequent motion parameter optimization and dynamic error compensation modeling.

Even with the state-of-the-art technology of computer-aided design and topology optimization, the present structural design still faces the challenges of high dimensionality, multi-objectivity, and multi-constraints, making it knowledge/experience-demanding, labor-intensive, and difficult to achieve or simply lack of global optimality. Structural designers are still searching for new ways to cost-effectively to achieve a possible global optimality in a given structure design, in particular, we are looking for decreasing design knowledge/experience-requirements and reducing design labor and time. In recent years, Artificial Intelligence (AI) technology, characterized by the large language model (LLM) of Machine Learning (ML), for instance Deep Learning (DL), has developed rapidly, fostering the integration of AI technology in structural engineering design and giving rise to the concept and notion of Artificial Intelligence-Aided Design (AIAD). The emergence of AIAD has greatly alleviated the challenges faced by structural design, showing great promise in extrapolative and innovative design concept generation, enhancing efficiency while simplifying the workflow, reducing the design cycle time and cost, and achieving a truly global optimal design. In this article, we present a state-of-the-art overview of applying AIAD to enhance structural design, summarizing the current applications of AIAD in related fields: marine and naval architecture structures, aerospace structures, automotive structures, civil infrastructure structures, topological optimization structure designs, and composite micro-structure design. In addition to discussing of the AIAD application to structural design, the article discusses its current challenges, current development focus, and future perspectives.

In performing structural design or demonstrating the reliability of electronic devices, it is necessary to take various scatters into consideration which are induced in the load assessment, material characteristics, stress analyses and manufacturing. Therefore, a new method for probabilistic reliability design for electronics packages is proposed in this paper. In this method, firstly the probability distributions of the characteristic values such as stress values are calculated by combining stress analysis, response surface methodology and the Monte Carlo method. Consequently, the fracture probability can be derived by comparison of the probability distributions with the design criteria. Secondly, the probability on many assumptions can be updated using a new method based on Bayes theory for the purpose of estimating the reliability of the packages more accurately in combination with actual data or reliability tests. The new method was applied for the structural design of flip-chip BGA packages. The results of the application fro flip-chip BGA package design indicate that the new method is useful for the structural reliability design.

The integration of redundant structures into robotic systems enhances the degrees of freedom (DOFs), flexibility, and capability to perform complex tasks. This study evaluates the mechanical performance of a 9-DOF series-parallel hybrid redundant device designed for rehabilitation training of patients with balance disorders. The redundant structural design improves the robot's movement flexibility, optimizes load distribution, and mitigates stress concentration in local joints or components. To optimize the robot's overall structural parameters and reduce joint driving forces, a genetic algorithm (GA) was employed. A custom dataset was created by collecting motion-related data, including foot posture and position. The robot's mechanical characteristics were comprehensively analyzed, followed by simulation experiments. The results demonstrate that incorporating the redundant structure, along with the optimization of structural parameters, significantly enhances the robot's mechanical performance. This study provides a solid foundation for the functional development and control system design of rehabilitation robots, extending the capabilities of existing systems and offering a novel, reliable, and efficient therapeutic tool for patients with balance disorders.

Facing the escalating demands in both technical competence and financial accountability, practicing structural engineers are being forced into an ever-intensified fast-pace working environment. With more and more structural design codes becoming lengthy and cumbersome and, meanwhile, the time allocated for structural engineering design being drastically reduced, the quality assurance of the structural engineering design has been becoming more critical than ever for practicing structural engineers to succeed. Structural engineering design errors and failures have been observed in a variety of design phases and categories. Among them, there are several typical problems needed to be discussed and a systematical procedure of quality assurance of the structural engineering design shall be studied and developed. As a part of our collective professional effort to assure the quality of the structural engineering design, this paper will discuss following eight typical aspects related to quality control and assurance of structural engineering design and a number of real world practical examples will be presented to assist in illustrating the importance of the quality control and assurance for real world structural engineering design projects.

This paper proposes and describes the controllers for doubly-fed induction generators (DFIG) with series grid side converter. It is demonstrated that with series grid side converter instead of a conventional shunt grid side converter the DFIG stator voltage can be kept balanced even under heavy unbalance grid voltages. Therefore, in this way it is avoided the undesired effects such as torque oscillations and high stator and rotor currents presents under unbalance voltages. In addition, it is demonstrated that it is possible with a conventional back-to-back three phase PWM converter to satisfy the grid code active and reactive power requirements. The design and control of the series grid-side converter with a LC-filter will also be presented. An H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">infin</sub> controller is designed to achieve robustness as well as good tracking and disturbance rejection performance for the series voltage converter. Furthermore, the DC-link, rotor currents and active and reactive power controllers are as well described, where the controllers transfer functions are selected to ensure good performance even in the presence of grid voltage unbalance. Finally, simulation results of a 2.27 MVA wind turbine generator are presented to demonstrate the good performance of the DFIG with the proposed controllers.

Power overhead line regulations and codes generally apply prescriptive methods to the design of structures using working loads multiplied by factors of safety. In contrast, the probabilistic method is founded on designing to a limit state in which strength is matched to stress, with the risk of failure defined by the overlap of the distributions of the limit state model. This work indicates how a stress limit state using probability concepts can be applied to the design of round pole distribution line structures. It indicates that unlike the transmission line, variations which occur in the layout of distribution lines necessitate the use of some contingency factors. Design studies of new and existing lines show that there are substantial savings to be made.

Empirical rule for predicting mechanical properties of Ti-6Al-4V bone implants with radial-gradient porosity bionic structures

This paper introduces a novel approach, namely Variable-Periodic Voronoi Tessellation (VPVT), for the bio-inspired design of porous structures. The method utilizes distributed points defined by a variable-periodic function to generate Voronoi tessellation patterns, aligning with a wide diversity of artificial or natural cellular structures. In this VPVT design method, the truss-based architecture can be fully characterized by design variables, such as frequency factors, thickness factors. This approach enables the optimal design of porous structures for both mechanical performance and functionality. The varied, anisotropic cell shapes and sizes of VPVT porous structures provide significantly greater design flexibility compared to typical isotropic porous structures. In addition, the VPVT method not only can design micro-macro multiscale materials, but is also applicable for the design of meso-macro scale truss-based porous structures, such as architecture constructions, biomedical implants, and aircraft frameworks. This work employs a Surrogate-assisted Differential Evolution (SaDE) method to perform the optimization process. Numerical examples and experiments validate that the proposed design achieves about 51.1% and 47.8% improvement in compliance performance and damage strength, respectively, than existing studies.

In this paper, according to the design technical requirements, the completion of the structural scheme design of compound-driven in-pipe robot, the establishment of the cam active support diameter reducing mechanism mathematical model, obtain the relationship curve between its parameters, and completed the optimization of the cam contour. The resident performance of the robot in the pipeline is analyzed, and the feasibility of the robot's active resident in the pipeline is verified. This paper explores the relationship between the running speed of the robot in the pipeline and the leakage clearance under the condition of the fluid driven, and through the analysis and calculation of the different fluid velocity in the pipe, the reasonable range of the leakage clearance of the robot can be determined, for this range the robot can run smoothly. It has important theoretical value and engineering practical significance for the design and practical application of compound-driven pipeline robot.

This paper deals with the design, modeling and control of a Tidal Stream Generator (TSG) system including a tidal turbine, a rotor shaft and a Doubly Fed Induction Generator (DFIG). Below high tidal speed the system is regulated so that for every tidal velocity reaches the maximum power. A rotational speed control based-Maximum Power Point Tracking (MPPT) for a TSG is investigated to provide the suitable rotational speed to the system in order to track the maximum power and thus keeping the pitch angle null. Two study cases were proposed to test the performance of the control strategy. The obtained results show that the proposed control provide satisfactory tracking of the MPPT reference.