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An Improved Modulation Strategy for Single-phase Three-level Neutral-point-clamped Converter in Critical Conduction Mode

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Journal of Modern Power Systems and Clean Energy 2024年第3期12卷 981-990页

作者： Ning Li Yujie Cao Xiaokang Liu Yan Zhang Ruotong Wang Lin Jiang Xiao-Ping Zhang School of Electrical Engineering Xi'an University of Technology the Department of Electronics Information and Bioengineering Xi'an Jiaotong University the Department of Electrical Engineering and Electronics University of Liverpool the Department of Electronic Electrical and Systems Engineering University of Birmingham

Two-level totem-pole power factor correction(PFC) converters in critical conduction mode(CRM) suffer from the wide regulation range of switching frequency. Besides, in highfrequency applications, the number of switching times increases, resulting in significant switching losses. To solve these issues, this paper proposes an improved modulation strategy for the single-phase three-level neutral-point-clamped(NPC) converter in CRM with PFC. By optimizing the discharging strategy and switching state sequence, the switching frequency and its variation range have been efficiently reduced. The detailed performance analysis is also presented regarding the switching frequency, the average switching times, and the effect of voltage gain. A 2 k W prototype is built to verify the effectiveness of the proposed modulation strategy and analysis results. Compared with the totem-pole PFC converter, the switching frequency regulation range of the three-level PFC converter is reduced by 36.48% and the average switching times is reduced by 45.10%. The experimental result also shows a 1.2% higher efficiency for the three-level PFC converter in the full load range.

关键词： switches Switching frequency Control systems Topology Bridge circuits Inductors Customer relationship management

Day-ahead Voltage-stability-constrained Network Topology Optimization with Uncertainties

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Journal of Modern Power Systems and Clean Energy 2024年第3期12卷 730-741页

作者： Dingli Guo Lei Wang Ticao Jiao Ke Wu Wenjing Yang the School of Electrical and Electronic Engineering Shandong University of Technology

A day-ahead voltage-stability-constrained network topology optimization(DVNTO) problem is proposed to find the day-ahead topology schemes with the minimum number of operations(including line switching and bus-bar splitting) while ensuring the sufficient hourly voltage stability margin and the engineering operation requirement of power systems. The AC continuation power flow and the uncertainty from both renewable energy sources and loads are incorporated into the formulation. The proposed DVNTO problem is a stochastic, largescale, nonlinear integer programming problem. To solve it tractably, a tailored three-stage solution methodology, including a scenario generation and reduction stage, a dynamic period partition stage, and a topology identification stage, is presented. First, to address the challenges posed by uncertainties, a novel problem-specified scenario reduction process is proposed to obtain the representative scenarios. Then, to obtain the minimum number of necessary operations to alter the network topologies for the next 24-hour horizon, a dynamic period partition strategy is presented to partition the hours into several periods according to the hourly voltage information based on the voltage stability problem. Finally, a topology identification stage is performed to identify the final network topology scheme. The effectiveness and robustness of the proposed three-stage solution methodology under different loading conditions and the effectiveness of the proposed partition strategy are evaluated on the IEEE 118-bus and 3120-bus power systems.

关键词： Power system stability switches Uncertainty Stability criteria Network topology Topology Renewable energy sources

Vibration-Based Fault Diagnosis for Railway Point Machines Using VMD and Multiscale Fluctuation-Based Dispersion Entropy

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Chinese Journal of Electronics 2024年第3期33卷 803-813页

作者： Yongkui SUN Yuan CAO Peng LI Guo XIE Tao WEN Shuai SU National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University School of Electronic and Information Engineering Beijing Jiaotong University Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing Xi'an University of Technology Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong University

As one of the most important railway signaling equipment,railway point machines undertake the major task of ensuring train operation safety.Thus fault diagnosis for railway point machines becomes a hot topic.Considering the advantage of the anti-interference characteristics of vibration signals,this paper proposes an novel intelligent fault diagnosis method for railway point machines based on vibration signals.A feature extraction method combining variational mode decomposition(VMD) and multiscale fluctuation-based dispersion entropy is developed,which is verified a more effective tool for feature selection.Then,a two-stage feature selection method based on Fisher discrimination and ReliefF is proposed,which is validated more powerful than single feature selection methods.Finally,support vector machine is utilized for fault diagnosis.Experiment comparisons show that the proposed method performs best.The diagnosis accuracies of normal-reverse and reverse-normal switching processes reach 100% and 96.57% respectively.Especially,it is a try to use new means for fault diagnosis on railway point machines,which can also provide references for similar fields.

关键词： Fault diagnosis Vibrations Support vector machines Diversity reception switches Feature extraction Rail transportation

Transient Damping of Virtual Synchronous Generator for Enhancing Synchronization Stability during Voltage Dips

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CES Transactions on Electrical Machines and Systems 2024年第2期8卷 143-151页

作者： Shitao Sun Yu Lei Guowen Hao Yi Lu Jindong Liu Zhaoxin Song Jie Zhang North China Electric Power Research Institute Co. Ltd. State Grid Xinyuan Co. Ltd. Hebei Fengning Pumped Storage Energy Co. Ltd.

Virtual synchronous generators(VSGs) are widely introduced to the renewable power generation, the variablespeed pumped storage units, and so on, as a promising gridforming solution. It is noted that VSGs can provide virtual inertia for frequency support, but the larger inertia would worsen the synchronization stability, referring to keeping synchronization with the grid during voltage dips. Thus, this paper presents a transient damping method of VSGs for enhancing the synchronization stability during voltage dips. It is revealed that the loss of synchronization(LOS) of VSGs always accompanies with the positive frequency deviation and the damping is the key factor to remove LOS when the equilibrium point exists. In order to enhance synchronization stability during voltage dips, the transient damping is proposed, which is generated by the frequency deviation in active power loop. Additionally, the proposed method can realize seamless switching between normal state and grid fault. Moreover, detailed control design for transient damping gain is given to ensure the synchronization stability under different inertia requirements during voltage dips. Finally, the experimental results are presented to validate the analysis and the effectiveness of the improved transient damping method.

关键词： Damping Voltage fluctuations Control design switches Power system stability Stability analysis Synchronous generators

Review of Three-phase Soft Switching Inverters and Challenges for Motor Drives

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CES Transactions on Electrical Machines and Systems 2024年第2期8卷 177-190页

作者： Haifeng Lu Qiao Wang Jianyun Chai Yongdong Li IEEE the Department of Electrical Engineering Tsinghua University the School of Electrical Engineering Xinjiang University the Department of Electrical Engineering Tsinghua University

For electric vehicles (EVs),it is necessary to improve endurance mileage by improving the efficiency.There exists a trend towards increasing the system voltage and switching frequency,contributing to improve charging speed and power density.However,this trend poses significant challenges for high-voltage and high-frequency motor controllers,which are plagued by increased switching losses and pronounced switching oscillations as consequences of hard switching.The deployment of soft switching technology presents a viable solution to mitigate these issues.This paper reviews the applications of soft switching technologies for three-phase inverters and classifies them based on distinct characteristics.For each type of inverter,the advantages and disadvantages are evaluated.Then,the paper introduces the research progress and control methods of soft switching inverters (SSIs).Moreover,it presents a comparative analysis among the conventional hard switching inverters (HSIs),an active clamping resonant DC link inverter (ACRDCLI) and an auxiliary resonant commuted pole inverter (ARCPI).Finally,the problems and prospects of soft switching technology applied to motor controllers for EVs are put forward.

关键词： Reviews Switching frequency Soft switching Switching loss switches Control systems Motors

Review of Fault-tolerant Control for Motor Inverter Failure with Operational Quality Considered

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CES Transactions on Electrical Machines and Systems 2024年第2期8卷 202-215页

作者： Yuxuan Du Wenxiang Zhao Yihua Hu Jinghua Ji Tao Tao School of Electrical and Information Engineering Jiangsu University Department of Engineering King’s College London

In recent years, motor drive systems have garnered increasing attention due to their high efficiency and superior control performance. This is especially apparent in aerospace, marine propulsion, and electric vehicles, where high performance, efficiency, and reliability are crucial. The ability of the drive system to maintain long-term fault-tolerant control(FTC) operation after a failure is essential. The likelihood of inverter failures surpasses that of other components in the drive system, highlighting its critical importance. Long-term FTC operation ensures the system retains its fundamental functions until safe repairs or replacements can be made. The focus of developing a FTC strategy has shifted from basic FTC operations to enhancing the post-fault quality to accommodate the realities of prolonged operation post-failure. This paper primarily investigates FTC strategies for inverter failures in various motor drive systems over the past decade. These strategies are categorized into three types based on post-fault operational quality: rescue, remedy, and reestablishment. The paper discusses each typical control strategy and its research focus, the strengths and weaknesses of various algorithms, and recent advancements in FTC. Finally, this review summarizes effective FTC techniques for inverter failures in motor drive systems and suggests directions for future research.

关键词： Inverters switches Fault tolerant systems Fault tolerance Circuit faults Motors Motor drives

Design of 85–105GHz Wideband Traveling Wave PIN Diode switches and Attenuators with Radial Stubs

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Chinese Journal of Electronics 2017年第1期26卷 218-222页

作者： YAO Changfei ZHOU Ming LUO Yunsheng ZHANG Junzhi WEI Xiang XU Conghai National Key Laboratory of Monolithic Integrated Circuits and Modules Nanjing Electronic Devices Institute Department of Microwave and Millimeter Wave Modules Nanjing Electronic Devices Institute

Wideband traveling wave PIN Diode switches and attenuators are proposed. The switches and attenuators consist of three shunt PIN diodes, six radial stubs, bias circuit and DC return circuit. Wide bandwidth is achieved with six different radial stubs as reflective load of the diodes. The stubs work as short circuit to the diodes at different frequency points for broad bandwidth. For the Single pole single throw(SPST) switch, the lowest measured Insertion loss(IL) is 0.75 dB and lower than 2.0dB in 85–105GHz, and its isolation is better than 21.3dB.As a Voltage-controlled variable attenuator(VCA), typical attenuation range is 23 dB and attenuation fluctuation is lower than 5dB in 85–105GHz.

关键词： Traveling wave switches Attenuators Radial stubs

Single-Crystalline Organoiridium Complex for Gas-Triggered Chromogenic switches and Its Applications on CO Detection and Reversible Scavenging

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Chinese Journal of Chemistry 2019年第8期37卷 763-768页

作者： Li-Ying Sun Yuan-Yuan An Li-Li Ma Ying-Feng Han Key Laboratory of Synthetic and Natural Functional Molecule Chemistry College of Chemistry and Materials ScienceNorthwest UniversityXi'anShaaxi 710127China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian 350002China

Summary of main observation and conclusion Nonporous molecular single crystals of coordinatively unsaturated 16-electron metallacycle are found to undergo highly selective-yet reversible-binding of CO over CH4,H2,N2,CO2,various volatile organic compounds and water,through binding of the molecule to its metal centers.Carbon monoxide is taken up by black crystals and subsequently liberated from the corresponding orange CO adduct by reversible metal coordination,the structural evidence obtained from in situ X-ray diffraction.The single-crystallinity of the metallacycle is retained even after several cycles.The material,when adsorbed on silica,shows remarkable sensitivity and selectivity for CO,allowing visual CO sensing in the solid state.The metallacycle offer the possibility of serving as readily regenerable scavenger for removing trace CO from gas mixtures with N2.

关键词： Gas-Triggered Chromogenic switches Applications CO Detection Reversible Scavenging

Study of the effect of switching speed of the a-SiC/c-Si(p)-based,thyristor-like,ultrahigh-speed switches,using two-dimensional simulation techniques

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Journal of Semiconductors 2017年第5期38卷 35-41页

作者： Evangelos I.Dimitriadis Nikolaos Georgoulas Informatics Engineering Department Technological Educational Institution of Central Macedonia Terma Magnisias 62124 Serres Greece Department of Electrical and Computer Engineering Democritus University of Thrace 67100 Xanthi Greece

A parametric study for a series of technological and geometrical parameters affecting rise time of Al/aSiC/c-Si（p）/c-Si（n~＋）/Al thyristor-like switches,is presented here for the first time,using two-dimensional simulation techniques.By varying anode current values in simulation procedure we achieved very good agreement between simulation and experimental results for the rising time characteristics of the switch.A series of factors affecting the rising time of the switches are studied here.Two factors among all others studied here,exerting most significant influence,of more than one order of magnitude on the rising time,are a-SiC and c-Si（p） region widths,validating our earlier presented model for device operation.The above widths can be easily varied on device manufacture procedure.We also successfully simulated the rising time characteristics of our earlier presented simulated improved switch,with forward breakover voltage V（BF） = 11 V and forward voltage drop VF = 9.5 V at the ON state,exhibiting an ultra low rise time value of less than 10 ps,which in conjunction with its high anode current density values of 12 A/mm^2 and also cheap and easy fabrication techniques,makes this switch appropriate for ESD protection as well as RF MEMS and NEMS applications.

关键词： simulation amorphous SiC switches rise time ESD protection

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