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7th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2015

作者： Li, Dawei Qu, Ronghai Li, Jian State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9781467371506

In this paper, one new machine family, i.e. named as flux-modulation machines which produce steady torque based on flux-modulation effect is proposed. The typical model including three components-one flux modulator, one armature and one excitation field exciters of flux-modulation machines is built. The torque relationships among the three components are developed based on the principle of electromechanical energy conversion. Then, some structure and performance features of flux-modulation machines are summarized, through which the flux-modulation topology distinguish criterion is proposed for the first time. Flux-modulation topologies can be further classified into stationary flux modulator, stationary excitation field, stationary armature field and dual-mechanical port flux-modulation machines. Many existed topologies, such as vernier, switched flux, flux reversal and transverse machines, are demonstrated that they can be classified into the flux-modulation family based on the criterion, and the processes how to convert typical models of flux-modulation machines to these machines are also given in this paper. Furthermore, in this new machine family, developed and developing theories on the vernier, switched flux, flux reversal and transverse machines can be shared with each other as well as some novel topologies in such a machine category. Based on the flux modulation principle, the nature and general theory, such as torque, power factor expressions and so on, of the flux-modulation machines are investigated. In additions, flux-modulation induction and electromagnetic transmission topologies are predicted and analyzed to enrich the flux-modulation electromagnetic topology family and the prospective applications are highlighted. Finally, one vernier permanent magnet prototype has been built and tested to verify the analysis results. © 2015 IEEE.

关键词： Topology

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Rotor design for a high-speed high-power permanent-magnet synchronous machine 7

Rotor design for a high-speed high-power permanent-magnet sy...

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7th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2015

作者： Fang, Haiyang Qu, Ronghai Li, Jian Zheng, Pei Fan, Xinggang State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9781467371506

Permanent-magnet synchronous machines (PMSMs) are considered a very promising machine type for high-speed applications nowadays. As permanent-magnet (PM) materials are generally fragile, a high strength sleeve is required to protect the PMs from damage due to extreme centrifugal forces. The rotor sleeve occupies space of the effective air gap of the PMSMs, so it is difficult to perform the electromagnetic (EM) design without an accurate estimation of the sleeve thickness, which is determined by mechanical issues. In this paper, an integrated mechanical-electromagnetic design method is presented for the rotor of a high-speed PMSM designed for 200 kW at 40,000 rpm. Three commonly used sleeve materials are investigated and their mechanical performances are analyzed. The mechanical strength limits for the proposed machine are calculated, as well as the EM design limits. The optimal dimensions for the rotors with different sleeves are then obtained by combining their strength and EM limits. The EM, thermal and rotor dynamic performances of the designed rotors are analyzed in order to select the best rotor type. In the end, a new rotor topology is proposed to reduce the rotor eddy current losses. The new rotor topology is characterized by a multi-layer sleeve which is thinner than a single-layer sleeve. The rotor losses are significantly lower in the new rotor and easier to be cooled. © 2015 IEEE.

关键词： Topology

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Design considerations and parameter optimization of stator wound field synchronous machines based on magnetic the gear effect 7

Design considerations and parameter optimization of stator w...

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7th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2015

作者： Jia, Shaofeng Qu, Ronghai Li, Jian State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9781467371506

Stator wound field synchronous machines (SWFSMs) are gaining more and more research and application interest recently due to the absence of expensive rare earth magnet materials. These machines are characterized by a doubly salient structure, and both the DC field winding and the three phase armature windings are located in the stator. In this paper, taking the basic structure of stator DC excited vernier reluctance machine, which is one type of SWFSM, the design of SWFSMs are studied in detail semi-analytically, by finite element analysis (FEA), and also validated by experiment. First, the effects of stator/rotor slot combinations on performances, including cogging torque, torque and torque ripple, voltage fluctuation of the DC winding are analyzed and compared. Then, the back-EMF, torque and power factor expressions in terms of the geometrical variables are proposed. Also, a 12-stator-slot, 11-rotor-slot machine as an example, the design parameters, including the split ratio, the air gap length, the proportion of the armature and field coil turns in one stator slot, and the stator/rotor tooth arc combination are optimized. The optimization results show that these design parameters have a various influence on electromagnetic performance, and the designers should select the design parameters comprehensively. © 2015 IEEE.

关键词： Stators

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Mechanical DC circuit breakers and FBSM-based MMCs in a high-voltage MTDC network: Coordinated operation for network riding through DC fault

Mechanical DC circuit breakers and FBSM-based MMCs in a high...

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International Conference on Renewable Power Generation, RPG 2015

作者： He, Zhen Hu, Jiabing Lin, Lei Zeng, Rong State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9781785610400

DC circuit breaker is of vital importance for security in a high voltage (HV) multi-terminal DC (MTDC) network, particularly in the HV MTDC based on voltage source converters (VSCs) that are typically based on two-level, neutral point clamed (NPC) three-level and modular multilevel. Mechanical DC circuit breaker characterized with low costs and losses has been widely used in the conventional LCC-based HV MTDC network, but cannot be directly applied in the VSC-based HV MTDC due to its slow response and limited breaking capacity. On the other hand, the technology of hybrid DC circuit breaker is immature at present, which has been demonstrated with prototype and cannot be employed in HV (≥320kV) applications in over ten years. As a result, DC circuit breaker has become an obstacle for HV MTDC development. This paper presents a kind of coordinated operation between mechanical DC breakers and full-bridge sub-module (FBSM) based MMCs to guarantee DC fault ride-through in a HV MTDC network. The proposed coordination strategy is dependent on the DC fault current controllability provided by FBSM-based MMC. Specifically, the capability of FBSM's negative level is adopted to change the common-mode component of MMC arm's reference voltage, which can restrain the fault current to the maximum operation threshold of mechanical DC circuit breaker. This scheme can reduce the demand of breaking capacity and response time for mechanical DC circuit breaker, which thus shows great potential in the applications of HV MMC-based MTDC network. The effectiveness and validity of the coordinated operation is verified by simulation results.

关键词： Electric circuit breakers

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Application of ultra-thin assembled planar metamaterial for wireless power transfer system

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Progress In electromagnetics Research C 2016年 65卷 153-162页

作者： Chen, Jun Feng Hu, Zhao Yang Wang, Shengming Liu, Minghai Cheng, Yongzhi Ding, Zhixia Wei, Bin Wang, Songcen State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Engineering Research Center for Metallurgical Automation and Detecting Technology Ministry of Education Wuhan University of Science and Technology Wuhan430081 China School of Automation Huazhong University of Science and Technology Wuhan430074 China China Electric Power Research Institute Beijing100192 China

Magnetically coupled resonant wireless power transfer (WPT) has been employed in many applications, including wireless charging of portable electronic devices, electric vehicles, etc. However, the power transfer efficiency (PTE) decreases sharply due to divergence of magnetic field. electromagnetic (EM) metamaterial (MM) can control the direction of magnetic fields due to its negative effective permeability. In this paper, MMs with negative effective permeability at radio frequencies (RF) are applied to a WPT system operating at around 16.30 MHz for improvement of PTE. This ultra- thin and assembled planar MM structure consists of a single-sided periodic array of the capaci-tively loaded split ring resonators (CLSRRs). Both simulation and experiment are performed to cha-racterize the WPT system with and without MMs. The results indicate that the contribution of high PTE is due to the property of negative effective permeability. By integrating MM in the WPT system, the experimental results verify that the measured PTE with one and two MM slabs have respectively 10% and 17% improvement compared to the case without MM. The measured PTEs of the system at different transmission distances are also investigated. Finally, the proposed MM slabs are applied in a more practical WPT system (with a light bulb load) to reveal its effects. The results verify the efficiency improvement by the realized power being transferred to the load. © 2016, electromagnetics Academy. All rights reserved.

关键词： Metamaterials

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Reliability model assessment of grid-connected solar photovoltaic system based on Monte-Carlo

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Applied Solar Energy (English translation of Geliotekhnika) 2015年第4期51卷 262-266页

作者： Wang, Haiying Zhu, Ninghui Bai, Xiaomin State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China CEPRI Science and Technology Company Beijing China China Electric Power Research Institute Beijing China

The rapid growth of photovoltaic PV energy utilization and the immense potential for future use dictate a need to seriously consider the reliability of PV system. In this study, the comprehensive model to assess the reliability of large-scale and grid-connected PV system was proposed, taking account of weather condition as well as critical component failure probability. In addition, the sequential Monte-Carlo simulation was also established, combining with the developed model. And this analytical approach was successfully applied to evaluate the practical PV system in western area of China. The result showed that the reliability increased as the system capacity increased. And the simulated value become more accurate when the basic model was modified by more factors, especially by weather condition. While for the fixed-capacity system, the reliability decreased periodically as the operation time prolonged, which was mainly caused by the PV modules and inverters failure probability. © 2015, Allerton Press, Inc.

关键词： Reliability

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Multifrequency Small-Signal Model of Voltage Source Converters Connected to a Weak Grid for Stability Analysis

Multifrequency Small-Signal Model of Voltage Source Converte...

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Annual IEEE Applied Power Electronics Conference and Exposition

作者： Xing Li Hua Lin State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781467395519

To investigate the instability issues of three-phase voltage source converters (VSCs) connected to a weak grid, this paper develops a modeling method based on the harmonic-balance approach. The nonlinear coordinate transformation in the control system would generate two sideband components. If the grid is not strong while the bandwidth of phase-locked loop (PLL) is high enough, the sideband components would be coupled, and both of them have influence on system stability, neither of them could be neglected. Hence, there would be two feedback loops of grid-current representing two sideband frequencies. Taking this effect into account, the multifrequency small-signal model is proposed. It is further demonstrated that the sum of the two grid-current loop gains determines the stability and transient performance. Simulations and experimental results were conducted to validate the analysis.

关键词： LCL filter grid-connected converter system stability weak grid PLL

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Reduction of sub-harmonic effect on the fractional slot concentrated winding interior PM machines by using spoke-type magnets

Reduction of sub-harmonic effect on the fractional slot conc...

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IEEE International Electric Machines and Drives Conference, IEMDC 2015

作者： Wang, Yawei Qu, Ronghai Wu, Leilei Fang, Haiyang Li, Dawei State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan Hubei430074 China

ISBN: (纸本)9781479979417

In this paper, a spoke-type IPM motor (buried with circumferentially magnetized magnets) with fractional-slot concentrated windings is designed to block the two-pole sub-harmonic and, thus, reduce the iron core losses and torque ripple. This is demonstrated by the comparison of a conventional V-type IPM configuration and a designed spoke-type machine. Both of them have 12-slot/10-pole configurations with the same stator structure. The simulation results indicate that under the same design specifications, the spoke-type motor has less magnet consumption and exhibits much smaller iron core losses and torque ripple than that of its V-type counterpart, especially when operated at high speed. Finally, the mechanical stress of the designed spoke-type machine rotor is analyzed by finite element analysis. © 2015 IEEE.

关键词： Finite element analysis fractional slot concentrated winding high speed mechanical stress permanent magnet machine spoke-type sub-harmonic V-type

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A review on electrical performances of nanocrystalline contact materials 21

A review on electrical performances of nanocrystalline conta...

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21st Symposium on Physics of Switching Arc 2015, FSO 2015

作者： Li, Z. Huang, J. Yang, X. Wei, J. State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology 1037 Luoyu Road Wuhan430074 China

ISBN: (纸本)9781510817203

Nano technology is one of new areas in material developments, and nanocrystalline contact materials, such as CuCr and AgSnO2, may have different electrical performances from microcrystalline contacts. A review is made in this paper to compare performance differences between nanocrystalline and microcrystalline contact materials, including arcing durations, welding behaviors, chopping currents, breakdown voltages, and breaking capacities.

关键词： Nanocrystals

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Short-term wind power completing and forecasting based on rough set and bp neural network

Short-term wind power completing and forecasting based on ro...

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International Conference on Power and Energy, CPE 2014

作者： Zeng, Y.F. Zhang, B.H. Wu, J.L. Jin, B.J. Li, M. Zhao, S. Wang, K. Zeng, D. State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology WuhanHubei China NanjingJiangsu China

ISBN: (纸本)9781138027824

When we use BP neural network to forecast the wind power, the selection of input variables is the key issue that affects the forecasting results. This paper proposes a method using rough set theory to solve this problem. On the basis of considering the correlation of the wind turbines, we use the Rough-Set analysis methods extract turbines which are strong associated, then use the wind power data of them as the partial inputs of BP neural network and build the RS-BP model (Neural network based on Rough-Set). For the case of wind power data missing, we use the RS-BP to complete the missing data. Then, we use the completed wind power data to forecast the wind power data. This method can select the inputs of neural network reasonably and has the better prediction accuracy. The numerical example shows that this method is effective and feasible. © 2015 Taylor and Francis Group.

关键词： Wind power

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