Table of Content

15 October 2020 Volume 33 Issue 10

  

Dual-input High-gain DC-DC Converter for New Energy Generation Systems

ZHU Yifeng,BAI Bingyang,WU Dangjian

Electronic Science and Technology. 2020, 33(10):  1-5.  doi:10.16180/j.cnki.issn1007-7820.2020.10.001

Abstract ( 393 )   HTML ( 15 )   PDF (787KB) ( 76 )  

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In the new energy combined power generation system, the multi-input DC-DC converter can simplify the system structure and reduce the cost, therefore it is widely used. In order to solve the problem of low output voltage and unstable power of the existing multi-input DC-DC converter, a novel dual-input high-gain DC-DC converter topology is proposed. Starting from the working principle of the dual-input DC-DC converter, the operating characteristics of the converter is analyzed, and the voltage gain under different working modes is calculated. The simulation results of MATLAB/Simulink in different modes show that the circuit topology had the advantages of high boost ratio, simple circuit topology, and the input sources can be allocated coordinately according to the load.

Research on the Power Control of Grid-connected Inverter Based on VSG

LIU Zhenxuan,YI Yingping,SHI Wei

Electronic Science and Technology. 2020, 33(10):  6-14.  doi:10.16180/j.cnki.issn1007-7820.2020.10.002

Abstract ( 447 )   HTML ( 12 )   PDF (1071KB) ( 87 )  

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The virtual synchronous generators enable grid-connected inverters to participate in the operation of power grid autonomously and provide support for the stability of the grid. In order to verify the control function of virtual synchronous generators and solve the shortcoming of large convergent disturbance of electromagnetic power, the mathematical model and control strategy of virtual synchronous generators are analyzed. An optimized virtual synchronous generator control strategy is proposed based on the method of synchronous rotation coordinate. Finally, a 15 kVA virtual synchronous generator simulation system is established and verified by the experiment of the processor in the loop. The experimental results demonstrate that the presented control strategy can not only perform good dynamic response features on power tracking and modulation of frequency and voltage, but also provide inertia and damping for the system. Moreover, the convergence disturbance of electromagnetic power is reduced, and the stability and flexibility of the system are significantly improved.

Study on Lateral Air Gap Control of a Detent-force-based Magnetic Suspension Platform

LU Jianfeng,XU Xiaozhuo,GAO Yan,DU Han

Electronic Science and Technology. 2020, 33(10):  15-20.  doi:10.16180/j.cnki.issn1007-7820.2020.10.003

Abstract ( 305 )   HTML ( 5 )   PDF (1067KB) ( 30 )  

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In order to solve the problem that the platform cannot be suspended stably due to the interference of lateral force, a fuzzy adaptive PID lateral air gap control system which can quickly adjust the parameters is designed. The structure of the suspension platform and its suspension mechanism are introduced in detail. The influence of lateral displacement on the platform is analyzed by finite element method, the static and dynamic mathematical models of the control system are established, and the fuzzy adaptive PID controller is designed. The lateral air gap control system of suspension platform is modeled and simulated by MATLAB/Simulink software. The simulation results showed that the fuzzy adaptive PID controller has fast response speed and strong robustness.

HEVC Efficiency Improvement Algorithm Based on Fast Coding Unit Partition and Adaptive Mode Decision

LUO Xiaolong,LIU Zilong

Electronic Science and Technology. 2020, 33(10):  21-25.  doi:10.16180/j.cnki.issn1007-7820.2020.10.004

Abstract ( 227 )   HTML ( 7 )   PDF (813KB) ( 45 )  

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In order to improve the coding efficiency of HEVC in real-time video, this study proposes an improved HEVC efficiency algorithm based on fast coding unit partition and adaptive mode decision. By using the separation depth information of the adjacent coding units on the top and left, it is determined whether the can coding unit could be separated or terminated early. When the condition is not satisfied, the coding unit can end its quad-tree separation by using the Rate-distortion cost threshold determined by training frame online learning. At the same time, the minimum Rate-distortion cost model and the second smallest Rate-distortion cost model were adopted to reduce the number of candidate sets and determine candidate set CS₅. Then, CS₅ is optimized to reduce the number of candidate Rate-distortion optimization. Finally, the Rate-Distortion optimization calculation was carried out to select the optimal mode to reduce the number of prediction modes. Experimental results show that compared with HM standard test results, the proposed algorithm can effectively reduce the video coding time of 45.93% under the premise of ensuring the coding quality, with only 0.597 8% of BDBR rising.

Spatial Trajectory Simulation and Analysis of Industrial Robot

ZHANG Kaixiang,CHEN Jiupeng,XIONG Binzhou,LI Qi,Hu Qiongqiong

Electronic Science and Technology. 2020, 33(10):  26-32.  doi:10.16180/j.cnki.issn1007-7820.2020.10.005

Abstract ( 604 )   HTML ( 26 )   PDF (1822KB) ( 92 )  

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Robot modeling and trajectory planning are the basis of robot control. For the structural of ABB_IRB120 industrial robot, the mathematical model is established by D-H method, and the workspace is analyzed by Monte Carlo method. The kinematics simulation of the robot and trajectory planning between two points are carried out by MATLAB Robotics Toolbox. Because of the limitations for the trajectory planning of Robotics Toolbox, it is redeveloped to increase a loop algorithm, extend the trajectory planning application ranges of this toolbox, and the robot effector is enabled to simulate the complex spatial curves. The real-time simulation experiments of the plane cosine curve and the spatial spiral curve show that the generated trajectory is consistent with the target trajectory, and the validity of the motion parameters is above 95.2%, which verifies the feasibility and effectiveness of the algorithm.

A Central Air Conditioning Measurement Method Based on Gaussian Mixture Model

QI Xin,ZHANG Li,WANG Fuzhong,WANG Xiaohui

Electronic Science and Technology. 2020, 33(10):  33-39.  doi:10.16180/j.cnki.issn1007-7820.2020.10.006

Abstract ( 245 )   HTML ( 6 )   PDF (1265KB) ( 32 )  

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With the large scale use of central air conditioners in colleges, accurate measurement and reasonable billing of central air conditioners has become an increasingly concerned issue for administrators and students. In order to solve the conflicts of interests between managers and users, a college dormitory’s central air conditioning measurement method based on Gaussian mixture model is proposed in this study. The method is based on the load characteristics of central air conditioning in college student dormitory, and uses Gaussian mixture model to analyze the probability and statistical characteristics of air conditioning load. By measuring the electricity consumption of central air conditioning and terminal fans, the calculus of time differences method based on its statistical characteristic is adopted to achieve split charging. The proposed method not only realize accurate metering and charge, but also combines the intelligent power management system to make the electricity process more transparent and has certain energy-saving effects.

Joint Design Scheme of RA Code and Network Coding

MIAO Lin,PENG Yaxiong,LU Anjiang

Electronic Science and Technology. 2020, 33(10):  40-44.  doi:10.16180/j.cnki.issn1007-7820.2020.10.007

Abstract ( 297 )   HTML ( 3 )   PDF (670KB) ( 27 )  

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In view of the problems of complex structure of coding and decoding system and poor stability of network transmission in existing coding technology, a joint design method of RA code and network coding is proposed. RA code combines the advantages of Turbo code and LDPC code. The BP decoding algorithm of RA code is adopted in this study. By adding the decoder of RA code into the information calculation process of PNC, the channel coding based on RA code is combined with PNC. Finally, the simulation is carried out by MATLAB platform. Based on AWGN channel, the SNR/BER performance curve is obtained. The simulation results show that the scheme effectively simplifies the system structure, reduces the signal-to-noise ratio and delay of the system, and improves the stability of transmission performance.

Design of Sensorless Control System for PMSM Based on Luenberger Observer

YAO Ying,LI Wei,JIN Hai,GUO Jie

Electronic Science and Technology. 2020, 33(10):  45-50.  doi:10.16180/j.cnki.issn1007-7820.2020.10.008

Abstract ( 803 )   HTML ( 24 )   PDF (1885KB) ( 191 )  

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Permanent magnet synchronous motor system based on low-resolution Hall position sensor has low estimation accuracy and slow response speed at medium and high speeds. To solve these problems, based on mathematical model of permanent magnet synchronous motor, the Luenberger observer and phase-locked loop are combined to propose a sensorless control algorithm of permanent magnet synchronous motor. The simulation model of the control system is established by MATLAB/Simulink tool to verify the feasibility of the control system. The superiority of the Luenberger observer over the Hall position sensor is verified by building the physical platform based on PAC5232. The experimental results show that the sensorless control system effectively improves the response speed and estimation accuracy of the system, making it to better track the rotor speed and rotor position information.

Chinese Short Text Similarity Calculation Based on TextRank Algorithm

LU Jiawei,CHEN Wei,YIN Zhong

Electronic Science and Technology. 2020, 33(10):  51-56.  doi:10.16180/j.cnki.issn1007-7820.2020.10.009

Abstract ( 617 )   HTML ( 17 )   PDF (819KB) ( 73 )  

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The traditional VSM vector space model often ignores text semantics, and the constructes text feature matrix is sparse. Based on the word vector technology of deep learning, this paper proposes a similarity calculation method that integrates the improved TextRank algorithm. This method uses the word vector embedding technology to build a text vector space, which makes the vector space model possess the semantic relevance. At the same time, with the improved TextRank algorithm to extract text keywords, the expression of text feature is enhanced and a large amount of redundant information is eliminated. The text characteristic of sparse matrix is reduced, which makes the text similarity computing more efficient. The results of the simulation experiments of different models show that the fusion of the improved TextRank algorithm with Bert word vector technology have better performance of text similarity calculation.

Analysis of Influences of Irregular Station Arrangement on Location Accuracy of TDOA System

LI Shihao,WANG Jian

Electronic Science and Technology. 2020, 33(10):  57-63.  doi:10.16180/j.cnki.issn1007-7820.2020.10.010

Abstract ( 273 )   HTML ( 5 )   PDF (3720KB) ( 59 )  

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In view of the problem that multi-base station radar system can not be regularly deployed due to the influence of topographic factors or mission conditions in practical engineering, the system positioning accuracy under various irregular station distribution conditions is analyzed by theoretical simulation in the current study. The influence of irregular station distribution on the system positioning accuracy is investigated from three aspects including the baseline length, the angle between baselines and the height difference between base stations. The location accuracy distribution law of the system in different locating areas under various conditions of irregular station distribution is obtained, which provides a theoretical basis for site selection of multi-base station radar in practical engineering.

Virtual Design and Verification of Lightweight Automotive Parts by Hot Pressing

XING Yuhang

Electronic Science and Technology. 2020, 33(10):  64-66.  doi:10.16180/j.cnki.issn1007-7820.2020.10.011

Abstract ( 239 )   HTML ( 3 )   PDF (710KB) ( 24 )  

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In order to meet the requirements of environmental protection and lightweight in China's automobile manufacturing industry, this study redesigns the B-pillar, the key component of automobile, based on hot pressing process. Then, The computer is used to validate the model of parts and components. In the process of modeling, the model of automobile parts under this process is established based on the finite element theory. At last, the vehicle crash experiment is designed according to the C-NCAP crash standard of our country. The simulation results showed that the quality of parts designed by this method can be reduced by 50% when compared with the traditional parts formed by cold pressing. At the same time, the passive safety of automobiles can be improved to a certain extent.

Design of Intelligent Aid System for Marine Automatic Control

XIAO Zuoming

Electronic Science and Technology. 2020, 33(10):  67-70.  doi:10.16180/j.cnki.issn1007-7820.2020.10.012

Abstract ( 357 )   HTML ( 5 )   PDF (560KB) ( 48 )  

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In view of the problem that traditional technology can not meet the requirement of modern automatic control intelligent system with general controllers such as PLC, this study designs an intelligent auxiliary system controller for marine automatic control based on DSP/F28335 by using DSP with high speed, good real-time performance and built-in CAN controller interface and variable universe PID control algorithm. The system structure is established and the variable universe PID algorithm is introduced. The perturbation experiments are carried out on the real-time hybrid simulation platform of the system, and the control effect based on the traditional PID controller system is compared. Experiments show that the DSP controller using variable universe fuzzy PID control algorithm greatly improves the real-time, anti-interference and self-adaptability of the marine automatic intelligent control auxiliary system.