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    30 December 2022, Volume 0 Issue 12
    Overview
    Review on Reliability Evaluation Methods for Small Samples of Electronic and Electrical Products
    ZHU Jiamiao, WANG Zhaobin, LI Jiuxin
    2022, 0(12):  1-7.  doi:10.16628/j.cnki.2095-8188.2022.12.001
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    The research status of reliability evaluation methods of electronic and electrical products with small samples is expounded.First of all,through the literature review at home and abroad,it is pointed out that the reliability evaluation of electronic and electrical products with small samples mainly includes two aspects:data preprocessing of small samples and reliability prediction modeling.Then,according to the above problems,several reliability evaluation methods,such as Bootstrap method and Bayes method are introduced,and their advantages and disadvantages are analyzed.Finally,the research on reliability evaluation methods of electronic and electrical products with small samples is prospected.

    Research & Analysis
    Research on Preparation and Properties of Nickel Coating on Connector Pin Surface by Magnetron Sputtering
    ZHANG Yue, ZHOU Xue, WANG Xu, ZHAI Guofu
    2022, 0(12):  8-12.  doi:10.16628/j.cnki.2095-8188.2022.12.002
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    In the surface coating of electrical connector contact,nickel is generally used as the transition layer between copper substrate and surface gold to improve wear resistance and prevent the mutual diffusion of gold and copper.Based on the orthogonal experimental method and DC magnetron sputtering technology,the nickel transition layer was prepared on the base surface of beryllium copper contact pin,and the thickness distribution,surface roughness and thermal shock bonding strength of nickel coating were tested.The influence of orthogonal process factors on the thickness and roughness characteristics of nickel coating was studied by range analysis.Finally,the best nickel plating process under the experimental conditions was obtained through the comprehensive analysis of the test results.

    Optimization of E-Type AC Contactor Electromagnetic System with Inclined Pole Surface
    YANG Cheng, ZHOU Yuyuan, LIU Xiangjun
    2022, 0(12):  13-19.  doi:10.16628/j.cnki.2095-8188.2022.12.003
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    E-type AC contactors are often used to frequently connect and disconnect medium and small capacity AC main circuits.The material utilization rate of the electromagnetic system is low and the contacts bounce is violent during the closing process.However,there is a certain slope angle and direction relationship between the center column and the side columns in E-type iron core with inclined pole sutface.If the design is improper,the iron core will be affected by the lateral component of electromagnetic attractive force which makes the closing process unstable.The multi-physics coupling joint simulation model is established.On the basis of considering the factors such as the angle of core inclined plane,magnetic ringstructure and energy and material saving,the electromagnetic system is optimized with the multi-strategy fusion particle swarm algorithm.According to the optimized results,a prototype is made and verified by experiments.The results show that the optimized inclined pole surface AC contactor can save energy and materials,reduce contact bounce,and has good dynamic characteristics and economic benefits.

    Neutral Point Potential Control Method Based on Coordinate Translation SVPWM
    WANG Jixiang, LI Zheng, WANG Han, CAO Yunfeng, ZHANG Jianwen, CAI Xu
    2022, 0(12):  20-27.  doi:10.16628/j.cnki.2095-8188.2022.12.004
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    Three-level rectifiers widely use space vector pulse width modulation(SVPWM) algorithm.Aiming at the cumbersome calculation of the traditional SVPWM algorithm and the imbalance of the DC side neutral point potential,a simple modulation algorithm based on coordinate translation and taking into account the balance control of neutral point potential is proposed.The validity of the proposed modulation algorithm is verified by the built rectifier experimental platform.At the same time,the time of the program using the balance factor precise control algorithm and the sector switching control algorithm is measured and compared,which can verify the simplicity of the sector switching algorithm.

    Electrical Design & Discussion
    Research on Automatic Measurement Method of Pick-Up Voltage and Release Voltage for Railway Signal Relay
    ZHANG Yinnan, WANG Jing, MENG Yuan, REN Wanbin
    2022, 0(12):  28-31.  doi:10.16628/j.cnki.2095-8188.2022.12.005
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    The accurate determination of the pick-up voltage and release voltage of railway signal relay is directly related to the products reliability evaluation.Firstly,The measurement principle of pick-up voltage and release voltage is described.Then the measurement system with the function of programming coil exciting voltage and capturing the contact voltage waveform is developed.The pick-up voltage,release voltage and reverse pick-up voltage parameters of railway signal relay are measured automatically.Taking a voltage-type relay as an example,the effects of coil voltage step and coil voltage step delay on the results are analyzed.Finally the measurement method considering both measurement accuracy and efficiency is ascertained.

    Electrical Design & Discussion
    Design of Integrated Lighting Power Supply Heat Dissipation
    YANG Kun, MA Shaohua, PANG Zheyuan, FENG Yuning
    2022, 0(12):  32-37.  doi:10.16628/j.cnki.2095-8188.2022.12.006
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    In order to solve the problem of the large size of the lighting lamp caused by the heat dissipation of the power supply,the heat dissipation of the power supply of the integrated lighting lamp is designed.First,the structure of the lamp is analyzed.Then,the losses of the power transformer and MOSFET are theoretically analyzed and calculated respectively using empirical formulas,and the simulation calculation of the temperature field of the power supply as a whole is completed using finite element software.Finally,the thermal design of the power supply is completed by redesigning the device of switching layout and transformer with the goal of minimizing the volume of the lighting lamp.The results show that the temperature rise of most compouents of the power supply has decreased after the thermal design,and the volume of the lighting lamp has decreased by 31.36%.The proposed heat dissipation design scheme effectively reduces the temperature rise of the power supply and the size of the lighting lamp.

    Design of Topology Identification Module for IOT Molded Case Circuit Breaker
    ZHOU Yunhong, HUANG Fei, WANG Yuying
    2022, 0(12):  38-45.  doi:10.16628/j.cnki.2095-8188.2022.12.007
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    For the construction of ubiquitous power stations,a new IOT molded case circuit breaker with built-in dedicated topology identification module is designed,which has the functions of characteristic current self-sending,self-receiving and self-detecting.The fast Fourier transform and power spectral density estimation are utilized to detect and distinguish the characteristic current signal.After the background fusion terminal queries the topology records of each circuit breaker,the level of each circuit breaker is determined according to the timestamp,and finally the substation area topology diagram is summarized.The proposed scheme has the advantages of small injected characteristic current,no influence on the quality of power grid,no need for the separate signal transmission and identification device,and simple circuit.The test and the operation results of the pilot station verify the feasibility and effectiveness of the method,which has certain engineering application value.

    Research and Experimental Verification of Copper Busbar Lap Scheme
    DAI Gang, GUO Qiaogen, CHEN Hong, WANG Yuxiao, YANG Quanbing
    2022, 0(12):  46-54.  doi:10.16628/j.cnki.2095-8188.2022.12.008
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    In order to study the main influencing factors of the contact resistance between bolted copper busbars,taking the rectangular copper busbars connected by standard bolts as the research object,the theoretical analysis,simulation analysis and experimental verification of the contact resistance between copper busbars are carried out.The research shows that the contact resistance mainly depends on the contact area and the contact pressure under the washer.Firstly,on the basis of theoretical analysis,the simulation model of bolted rectangular copper busbar is established by using multi physical field coupling finite element analysis software.Furthermore,the simulation analysis of connection resistance under different bolt pretightening force and different lap length is carried out.Finally,the experimental results of connection resistance are compared with the simulation results to verify the correctness of the proposed conclusion.

    Distributed Generation and Grid-Connection Technology
    Common Mode Noise Suppression of Buck Converter Based on Anti-Phase Winding Method
    PENG Jinrong, MAO Xingkui, CUI Wenling, ZHANG Yiming
    2022, 0(12):  55-60.  doi:10.16628/j.cnki.2095-8188.2022.12.009
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    The power switching devices of Buck converter will produce high du/dt during the switching process,which will resulte serious conducted common mode electromagnetic interference.To solve the above problems,the anti-phase winding method is proposed to suppress the conducted common mode noise of Buck converter.By analyzing the common mode noise suppression mechanism of the proposed method,the common mode noise suppression equivalent model considering the influence of high-frequency parasitic parameters and its insertion loss mathematical model are established,and the parameter design method of Buck converter anti-phase winding method is proposed accordingly.Taking a high-power industrial lighting LED driving power supply as the test object,the correctness and effectiveness of the proposed method are verified.The experimental results show that the anti-phase winding method can effectively suppress the conducted common mode noise of Buck converter.

    SVPWAM Modulation Strategy and Its Loss Analysis for Current Source Inverter
    ZHAO Yun, AI Yuangao, XIANG Qiangming, XIA Guoqiang, HUANG Jiazhi
    2022, 0(12):  61-69.  doi:10.16628/j.cnki.2095-8188.2022.12.010
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    In order to reduce the number of switching operations and increase the power density of the inverter system,a SVPWAM modulation strategy is proposed.Compared with the traditional muti-segment SVPWM modulation strategy,the proposed strategy reduces the number of switching states in the sector by proportionally allocating the action time of the traditional(pass-through) zero vector to the effective vector.At the same time,through reasonable selection and insertion of non-traditional(open) zero vectors,it can ensure that there is only one switch tube operation when switching the switch state,which can reduce the number of switching actions and switching losses.In order to analyze the device of switching loss under the modulation method in detail,the co-simulation model of the traditional multi-segment SVPWM and SVPWAM modulation methods is constructed by using Slimlink and PLECS software,and the device of losses and analysis under two different modulation modes are given based on the experimental results.

    Optimal Voltage Support Strategy for Permanent Magnet Direct Drive Fan Under Asymmetric Fault
    GU Chunsong, CHEN Zhong, XIE Hui
    2022, 0(12):  70-77.  doi:10.16628/j.cnki.2095-8188.2022.12.011
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    In order to optimize the point of common coupling(PCC)voltage support strategy of permanent magnet direct drive fan under asymmetric faults,the instantaneous power during asymmetrical faults of the power grid is firstly analyzed,and the expressions of each sequence component of the grid-side converter(GSC) incoming current are obtained to eliminate the double frequency fluctuation of active power.Then,the support principle of GSC power injection to PCC voltage is analyzed.At same time,a positive and negative sequence active and reactive current distribution strategy based on the grid impedance ratio is proposed to eliminate the active power double frequency fluctuation,effectively support PCC positive sequence voltage and effectively suppress negative sequence voltage.Simulation results verify the effectiveness of the proposed strategy.

    Prediction of Short Term Wind Speed Based on Grey Residual Marko Model
    WANG Jinhui, WANG Juanjuan
    2022, 0(12):  78-82.  doi:10.16628/j.cnki.2095-8188.2022.12.012
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    On the basis of grey system theory,the GM(1,1) prediction model is improved and promoted to form the grey residual model.The grey residual prediction model is improved by Markov prediction idea,and the improved model is applied to the short-term wind speed prediction of wind farms.Through modeling and simulation,the model is applied to literature [1],and the prediction results prove the effectiveness of the proposed method.The improved prediction model has higher accuracy and better prediction effect than the traditional grey model,which provides asimple and accurate new method for wind speed prediction.