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Multi-objective design optimization of a large-scale direct-drive permanent magnet generator for wind

Arash Hasssanpour ISFAHANI,Amirhossein Haji-Seyed BOROUJERDI,Saeed HASANZADEH

《能源前沿（英文）》 2014年第8卷第2期页码 182-191 doi: 10.1007/s11708-014-0320-z

摘要： This paper presents a simultaneous multi-objective optimization of a direct-drive permanent magnet synchronous generator and a three-blade horizontal-axis wind turbine for a large scale wind energy conversion system. Analytical models of the generator and the turbine are used along with the cost model for optimization. Three important characteristics of the system i.e.,the total cost of the generator and blades, the annual energy output and the total mass of generator and blades are chosen as objective functions for a multi-objective optimization. Genetic algorithm (GA) is then employed to optimize the value of eight design parameters including seven generator parameters and a turbine parameter resulting in a set of optimal solutions. Four optimal solutions are then selected by applying some practical restrictions on the front. One of these optimal designs is chosen for finite element verification. A circuit-fed coupled time stepping finite element method is then performed to evaluate the no-load and the full load performance analysis of the system including the generator, a rectifier and a resistive load. The results obtained by the finite element analysis (FEA) verify the accuracy of the analytical model and the proposed method.

关键词： permanent magnet synchronous generator wind turbine direct-drive multi-objective optimization cost mass annual energy output finite element analysis (FEA)

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Overview of condition monitoring and operation control of electric power conversion systems in direct-drive

Shoudao HUANG, Xuan WU, Xiao LIU, Jian GAO, Yunze HE

《机械工程前沿（英文）》 2017年第12卷第3期页码 281-302 doi: 10.1007/s11465-017-0442-1

摘要：

Electric power conversion system (EPCS), which consists of a generator and power converter, is one of the most important subsystems in a direct-drive wind turbine (DD-WT). However, this component accounts for the most failures (approximately 60% of the total number) in the entire DD-WT system according to statistical data. To improve the reliability of EPCSs and reduce the operation and maintenance cost of DD-WTs, numerous researchers have studied condition monitoring (CM) and fault diagnostics (FD). Numerous CM and FD techniques, which have respective advantages and disadvantages, have emerged. This paper provides an overview of the CM, FD, and operation control of EPCSs in DD-WTs under faults. After introducing the functional principle and structure of EPCS, this survey discusses the common failures in wind generators and power converters; briefly reviewed CM and FD methods and operation control of these generators and power converters under faults; and discussed the grid voltage faults related to EPCSs in DD-WTs. These theories and their related technical concepts are systematically discussed. Finally, predicted development trends are presented. The paper provides a valuable reference for developing service quality evaluation methods and fault operation control systems to achieve high-performance and high-intelligence DD-WTs.

关键词： direct-drive wind turbine electric power conversion system condition monitoring fault diagnosis operation control under faults fault tolerance

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Design and analysis of a new high frequency double-servo direct drive rotary valve

Muzhi ZHU,Shengdun ZHAO,Jingxiang LI

《机械工程前沿（英文）》 2016年第11卷第4期页码 344-350 doi: 10.1007/s11465-016-0406-x

摘要：

Researchers have investigated direct drive valve for many years to solve problems, such as fluid force imbalance and switching frequency. The structure of the rotary valve has received considerable research interest because of its favorable dynamic properties and simple structure. This paper studied the high frequency double-servo direct drive rotary valve (DDRV), and proposed a novel structure and drive method satisfying high reversing frequency and adequate quantity of flow. Servo motors are integrated into the valve by the innovative structure, which is designed to equilibrate the unbalanced radial fluid force with the symmetric distributed oil ports. Aside from the fast reversing function of the valve, the DDRV presented high performance in linearity of the flow quantity and valve opening as a result of the fan-shaped flow ports. In addition, a computational fluid dynamics (CFD) method based on Fluent was conducted to verify the flux regulation effect of the height change of the adjustable boss.

关键词： direct drive rotary valve computational fluid dynamics (CFD) flow regulation

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System construction of a four-side primary permanent-magnet linear motor drive mechanical press

Jintao LIANG, Zhengfeng MING, Peida LI

《机械工程前沿（英文）》 2020年第15卷第4期页码 600-609 doi: 10.1007/s11465-020-0597-z

摘要： A primary permanent-magnet linear motor (PPMLM) has a robust secondary structure and high force density and is appropriate for direct-drive mechanical press. The structure of a four-side PPMLM drive press is presented based on our previous research. The entire press control system is constructed to realize various flexible forming processes. The control system scheme is determined in accordance with the mathematical model of PPMLM, and active disturbance rejection control is implemented in the servo controller. Field-circuit coupling simulation is applied to estimate the system’s performance. Then, a press prototype with 6 kN nominal force is fabricated, and the hardware platform of the control system is constructed for experimental study. Punch strokes with 0.06 m displacement are implemented at trapezoidal speeds of 0.1 and 0.2 m/s; the dynamic position tracking errors are less than 0.45 and 0.82 mm, respectively. Afterward, continuous reciprocating strokes are performed, and the positioning errors at the bottom dead center are less than 0.015 mm. Complex pulse trajectories are also achieved. The proposed PPMLM drive press exhibits a fast dynamic response and favorable tracking precision and is suitable for various forming processes.

关键词： mechanical press direct drive primary permanent-magnet linear motor (PPMLM) servo system active disturbance rejection control (ADRC) prototype experiment

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Electromagnetic interference modeling and suppression techniques in variable-frequency drive systems

Le YANG, Shuo WANG, Jianghua FENG

《机械工程前沿（英文）》 2018年第13卷第3期页码 329-353 doi: 10.1007/s11465-018-0466-1

摘要：

Electromagnetic interference (EMI) causes electromechanical damage to the motors and degrades the reliability of variable-frequency drive (VFD) systems. Unlike fundamental frequency components in motor drive systems, high-frequency EMI noise, coupled with the parasitic parameters of the trough system, are difficult to analyze and reduce. In this article, EMI modeling techniques for different function units in a VFD system, including induction motors, motor bearings, and rectifier-inverters, are reviewed and evaluated in terms of applied frequency range, model parameterization, and model accuracy. The EMI models for the motors are categorized based on modeling techniques and model topologies. Motor bearing and shaft models are also reviewed, and techniques that are used to eliminate bearing current are evaluated. Modeling techniques for conventional rectifier-inverter systems are also summarized. EMI noise suppression techniques, including passive filter, Wheatstone bridge balance, active filter, and optimized modulation, are reviewed and compared based on the VFD system models.

关键词： variable-frequency drive (VFD) electromagnetic interference (EMI) motor drive modeling EMI noise suppression

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Power control of dual-motor electric drive for tracked vehicles

Yuan ZOU, Chengning ZHANG, Fengchun SUN, Jingbo WU,

《机械工程前沿（英文）》 2010年第5卷第1期页码 67-72 doi: 10.1007/s11465-009-0059-0

摘要： The fundamental problem of the power control for the driving of a dual-motor drive electric tracked vehicle is analyzed. The tracked vehicle and its electric drive system are mathematically modeled. Power control schemes of the dual-motor drive system is put forward, designed, and analyzed, including the distributed control system and the two control schemes speed-regulation and torque-regulation. The field experiment shows that the two types of drive control schemes realize the driving function of the vehicle feasibly and effectively. Obviously the comprehensive controller and two motors’ controllers are closely coupled in the “speed-regulation” control scheme, in which they must coordinate very well to guarantee the control. Contrastingly, in the “torque-regulation” control scheme, the comprehensive controller and two motors’ controller are not dependent closely when the accuracy and response of the torque controlling is guaranteed. The latter is simpler and more practical than the former.

关键词： control electric drive tracked vehicle

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An investigation into the vibration of harmonic drive systems

M. Masoumi, H. Alimohammadi

《机械工程前沿（英文）》 2013年第8卷第4期页码 409-419 doi: 10.1007/s11465-013-0275-5

摘要：

Harmonic drive systems are precise and specific transmission gear systems which are beneficial in terms of the high transmission ratio and almost zero backlash. These inherent and spectacular properties result in using this mechanism in robotic and space sciences where the precision and lightwieght play an important role. This paper presents a vibration analysis of harmonic drive systems using the shell theory. Equations of vibration for the flexspline and the circular spline of the system are derived and used to find the natural frequencies for both parts and, moreover, vibration response of the system under the operating condition is calculated. Also, obtained vibration equations are utilized to study the effects of different involved parameters such as the geometry of the flexspline and its gear tooth, eccentricity, and unbalancing on the vibrational behavior of the system.

关键词： harmonic drive system strain wave gearing mechanism vibration analysis natural frequencies

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SCRaMbLE drive application of synthetic yeast genome

Jin Jin, Yuan Ma, Duo Liu

《化学科学与工程前沿（英文）》 2018年第12卷第4期页码 832-834 doi: 10.1007/s11705-018-1749-0

摘要：

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Effects of elastic support on the dynamic behaviors of the wind turbine drive train

Shuaishuai WANG, Caichao ZHU, Chaosheng SONG, Huali HAN

《机械工程前沿（英文）》 2017年第12卷第3期页码 348-356 doi: 10.1007/s11465-017-0420-7

摘要：

The reliability and service life of wind turbines are influenced by the complex loading applied on the hub, especially amidst a poor external wind environment. A three-point elastic support, which includes the main bearing and two torque arms, was considered in this study. Based on the flexibilities of the planet carrier and the housing, a coupled dynamic model was developed for a wind turbine drive train. Then, the dynamic behaviors of the drive train for different elastic support parameters were computed and analyzed. Frequency response functions were used to examine how different elastic support parameters influence the dynamic behaviors of the drive train. Results showed that the elastic support parameters considerably influenced the dynamic behaviors of the wind turbine drive train. A large support stiffness of the torque arms decreased the dynamic response of the planet carrier and the main bearing, whereas a large support stiffness of the main bearing decreased the dynamic response of planet carrier while increasing that of the main bearing. The findings of this study provide the foundation for optimizing the elastic support stiffness of the wind turbine drive train.

关键词： wind turbine drive train elastic support dynamic behavior frequency response function

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Hierarchical parameter estimation of DFIG and drive train system in a wind turbine generator

Xueping PAN, Ping JU, Feng WU, Yuqing JIN

《机械工程前沿（英文）》 2017年第12卷第3期页码 367-376 doi: 10.1007/s11465-017-0429-y

摘要：

A new hierarchical parameter estimation method for doubly fed induction generator (DFIG) and drive train system in a wind turbine generator (WTG) is proposed in this paper. Firstly, the parameters of the DFIG and the drive train are estimated locally under different types of disturbances. Secondly, a coordination estimation method is further applied to identify the parameters of the DFIG and the drive train simultaneously with the purpose of attaining the global optimal estimation results. The main benefit of the proposed scheme is the improved estimation accuracy. Estimation results confirm the applicability of the proposed estimation technique.

关键词： wind turbine generator DFIG drive train system hierarchical parameter estimation method trajectory sensitivity technique

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Meshing stiffness property and meshing status simulation of harmonic drive under transmission loading

《机械工程前沿（英文）》 2022年第17卷第2期 doi: 10.1007/s11465-022-0674-6

摘要： The multitooth meshing state of harmonic drive (HD) is an important basic characteristic of its high transformation precision and high bearing capacity. Meshing force distribution affects the load sharing of the tooth during meshing, and theoretical research remains insufficient at present. To calculate the spatial distributed meshing forces and loading backlashes along the axial direction, an iterative algorithm and finite element model (FEM) is proposed to investigate the meshing state under varied transmission loading. The displacement formulae of meshing point under tangential force are derived according to the torsion of the flexspline cylinder and the bending of the tooth. Based on the relationship of meshing forces and circumferential displacements, meshing forces and loading backlashes in three cross-sections are calculated with the algorithm under gradually increased rotation angles of circular spline, and the results are compared with FEM. Owing to the taper deformation of the cup-shaped flexspline, the smallest initial backlash and the earliest meshing point appear in the front cross-section far from the cup bottom, and then the teeth in the middle cross-section of the tooth rim enter the meshing and carry most of the loading. Theoretical and numerical research show that the flexibility is quite different for varied meshing points and tangential force amplitude because of the change of contact status between the flexspline and the wave generator. The meshing forces and torsional stiffness of the HD are nonlinear with the torsional angle.

关键词： harmonic drive meshing flexibility matrix meshing force loading backlash flexspline contact analysis

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CRITICAL PROCESSES AND MAJOR FACTORS THAT DRIVE NITROGEN TRANSPORT FROM FARMLAND TO SURFACE WATER BODIES

《农业科学与工程前沿（英文）》 2023年第10卷第4期页码 541-552 doi: 10.15302/J-FASE-2023518

摘要：

Agricultural non-point source pollution is increasingly an important issue affecting surface water quality. Currently, the majority of the studies on nitrogen loss have focused on the agricultural field scale, however, the response of surface water quality at the watershed scale into the nitrogen loss at the field scale is poorly understood. The present study systematically reviewed the critical processes and major factors that nitrogen transport from farm fields to surface water bodies. The critical processes of farmland nitrogen entering surface water bodies involve the processes of nitrogen transport from farmland to ditches and the transformation processes of nitrogen during migration in ditches/rivers. Nitrogen transport from farmland to ditches is one of the prerequisites and critical processes for farmland nitrogen transport to surface water bodies. The transformation of nitrogen forms in ditches/rivers is an intermediate process in the migration of nitrogen from farmland to surface water bodies. Nitrogen loss from farmland is related to soil storage and exogenous inputs. Therefore, nitrogen input management should not only consider the current input, but also the contribution of soil storage due to the historical surpluses. Ditches/rivers have a strong retention capacity for nitrogen, which will significantly affect the process of farmland nitrogen entering surface water bodies. The factors affecting nitrogen transformation in river/ditches can be placed in four categories: (1) factors affecting hydraulic retention time, (2) factors affecting contact area, (3) factors affecting biological activity, and (4) forms and amount of nitrogen loading to river/ditches. Ditch systems are more biologically (including plants and microbes) active than rivers with biological factors having a greater influence on nitrogen transformation. When developing pollution prevention and control strategies, ecological ditches can be constructed to increase biological activity and reduce the amount of surplus nitrogen entering the water body. The present research should be valuable for the evaluation of environment impacts of nitrogen loss and the non-point source pollution control.

关键词： nitrogen loss from soil transformation farm field scale watershed scale

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Additive direct-write microfabrication for MEMS: A review

Kwok Siong TEH

《机械工程前沿（英文）》 2017年第12卷第4期页码 490-509 doi: 10.1007/s11465-017-0484-4

摘要：

Direct-write additive manufacturing refers to a rich and growing repertoire of well-established fabrication techniques that builds solid objects directly from computer-generated solid models without elaborate intermediate fabrication steps. At the macroscale, direct-write techniques such as stereolithography, selective laser sintering, fused deposition modeling ink-jet printing, and laminated object manufacturing have significantly reduced concept-to-product lead time, enabled complex geometries, and importantly, has led to the renaissance in fabrication known as the . The technological premises of all direct-write additive manufacturing are identical—converting computer generated three-dimensional models into layers of two-dimensional planes or slices, which are then reconstructed sequentially into three-dimensional solid objects in a layer-by-layer format. The key differences between the various additive manufacturing techniques are the means of creating the finished layers and the ancillary processes that accompany them. While still at its infancy, direct-write additive manufacturing techniques at the microscale have the potential to significantly lower the barrier-of-entry—in terms of cost, time and training—for the prototyping and fabrication of MEMS parts that have larger dimensions, high aspect ratios, and complex shapes. In recent years, significant advancements in materials chemistry, laser technology, heat and fluid modeling, and control systems have enabled additive manufacturing to achieve higher resolutions at the micrometer and nanometer length scales to be a viable technology for MEMS fabrication. Compared to traditional MEMS processes that rely heavily on expensive equipment and time-consuming steps, direct-write additive manufacturing techniques allow for rapid design-to-prototype realization by limiting or circumventing the need for cleanrooms, photolithography and extensive training. With current direct-write additive manufacturing technologies, it is possible to fabricate unsophisticated micrometer scale structures at adequate resolutions and precisions using materials that range from polymers, metals, ceramics, to composites. In both academia and industry, direct-write additive manufacturing offers extraordinary promises to revolutionize research and development in microfabrication and MEMS technologies. Importantly, direct-write additive manufacturing could appreciably augment current MEMS fabrication technologies, enable faster design-to-product cycle, empower new paradigms in MEMS designs, and critically, encourage wider participation in MEMS research at institutions or for individuals with limited or no access to cleanroom facilities. This article aims to provide a limited review of the current landscape of direct-write additive manufacturing techniques that are potentially applicable for MEMS microfabrication.

关键词： direct-write additive manufacturing microfabrication MEMS

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Novel drive mechanism for in-tube micro robots

CHEN Yangzhi, XING Guangquan, PENG Xuefei, LIU Wenguang, YAO Huaping

《机械工程前沿（英文）》 2007年第2卷第1期页码 94-98 doi: 10.1007/s11465-007-0016-8

摘要： The volume of an in-tube micro robot is small and its interior space is very limited. However, conventional transmission methods are unfit to drive in-tube micro robots. A novel micro drive mechanism called the micro-elastic-meshing-wheel is presented in this paper. It can be used for transmitting power and locomotion between two shafts, which are upright and cross in a micro space. The mechanical model of the novel drive mechanism is built, and the maximal transmission force is deduced. Then, sufficient experiments are carried out to test maximal transmission force produced by the novel drive mechanism. The calculation and experiment results show that the novel drive mechanism can transmit sufficient power to in-tube micro robots.

关键词： limited conventional transmission maximal transmission upright calculation