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15 January 2022 Volume 35 Issue 1
  
    A Synthesis Method for Dual-Band Filters with Frequency Variant Couplings
    LI Gang
    Electronic Science and Technology. 2022, 35(1):  1-5.  doi:10.16180/j.cnki.issn1007-7820.2022.01.001
    Abstract ( 162 )   HTML ( 10 )   PDF (691KB) ( 81 )  
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    In order to solve the problem of the lack of effective synthesis method for frequency-varying coupled dual-band filter, an optimized synthesis method is proposed in this study. First, the characteristic polynomials of the filter in the normalized dual pass band domain are obtained using the frequency transformation technique. Then, the classical coupling matrix synthesis method is used to obtain the canonical coupling matrix of the dual band filter and the cost function is constructed with the eigenvalues of the matrix as the approach target. Finally, the coupling matrix can be obtained by gradient optimization algorithm. The symmetrical and asymmetrical frequency-variable coupled dual band filters are verified. The verification results show that the dual-band of the two types of filters can better maintain the iso-ripple characteristics, which proves the effectiveness of the integrated method.

    A Large-Scale Antenna Array Radome Decoupling Technology Based on Electromagnetic Metamaterials
    CHEN Zhenghong,JIANG Yuanzhen,HOU Jianqiang
    Electronic Science and Technology. 2022, 35(1):  6-11.  doi:10.16180/j.cnki.issn1007-7820.2022.01.002
    Abstract ( 214 )   HTML ( 11 )   PDF (1823KB) ( 43 )  
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    In this study, a decoupling radome is designed to provide a reference for solving the problem of low isolation between adjacent ports in a compactly arranged large-scale antenna array. The main body of the radome is a layer of dielectric plate with low dielectric constant and low loss, on which a periodically arranged metal patch structure is printed. By adjusting the shape of the metal patch and the distance between the radome and the antenna array, the reflected wave generated by the radome and the coupled wave in the array have the same amplitude and opposite phase,and the two cancel each other out, thereby achieving the effect of increasing the isolation between the ports in the array. The test results show that the isolation of the different polarization in the antenna array unit before loading the decoupling radome is about -20 dB, and the isolation of the same polarization is about -22 dB. After loading the radome, the heteropolarization isolation in the unit is improved by about 8 dB at 2.5~2.61 GHz.The co-polarization isolation between the units has also been significantly improved, which is improved by about 10 dB at the 2.6 GHz frequency point. Moreover,there is basically no effect on the radiation characteristics of the antenna array before and after loading the decoupling radome.

    A New Type of Suspension Magnet Structure for Double-Degree-of-Freedom Vibration Energy Harvester of Axle Box for Railway Vehicle
    LI Zhehui,YUAN Tianchen,YANG Jian,SONG Ruigang
    Electronic Science and Technology. 2022, 35(1):  12-20.  doi:10.16180/j.cnki.issn1007-7820.2022.01.003
    Abstract ( 98 )   HTML ( 7 )   PDF (4164KB) ( 28 )  
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    In view of the self-supplying problem of the real-time monitoring system of railway vehicle axle temperature, this study proposes a new type of double-degree-of-freedom vibration energy harvester of railway vehicle axle box with suspended magnet structure.The proposed harvester can be used to convert the vibration energy existing in the working environment of the vehicle axle box into electrical energy. Based on the mechanical lumped system model and the electromechanical coupling model, the finite element model of the double-degree-of-freedom vibration energy harvester is constructed through multi-physics coupling. A new type of suspension magnet structure is designed by adding the inner ring radiating magnetizing magnet, and the output characteristics of the vibration energy harvester under harmonic excitation are studied. Compared with the copper block-permanent magnet composite suspension magnet structure, the output performance of the proposed structure is increased by 165%. The peak output current of the energy harvester system is 63.0 mA and the peak power is 13.22 mW. This research provides theoretical guidance for improving the response characteristics and output performance of the magnetic levitation vibration energy harvester.

    Automatic Detection Method of Crane Track Altitude Difference Based on Spot Position
    ZONG Shengkang,CHENG Jianpeng,ZHANG Xiliang
    Electronic Science and Technology. 2022, 35(1):  21-28.  doi:10.16180/j.cnki.issn1007-7820.2022.01.004
    Abstract ( 89 )   HTML ( 6 )   PDF (1425KB) ( 11 )  
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    The automatic detection technology of crane track is immature, which cannot meet the requirements of the track detection. In view of this problem, an automatic detection method of crane track altitude based on the position of the light spot image is proposed. A laser launcher and an imaging board are placed on both sides of the track. The laser is transmitted and projected on the imaging board to form a spot image. The gray-scale distribution of the light spot image is trimmed to enhance the difference between image sharpness and gray-scale distribution. The improved two-dimensional Otsu algorithm is used to accurately segment the spot image, and the edge of the spot is extracted for circle fitting. The center coordinates of the edge fitting circle are calculated to complete the spot image position recognition. Moreover, the position deviation of the light spot in the vertical direction is calculated to obtain the height difference between the two detection points of the crane track. Experimental research shows that the average error of spot image position recognition using the detection method of spot position recognition in this study is about ±0.22 mm, and the maximum error does not exceed ±0.4 mm. Compared with the traditional method of spot image position recognition, the accuracy of the proposed methed is improved by about 0.10 mm. Based on the track height difference of the spot position, the average error of detection is about ±0.8 mm, and the error range is ±1.8 mm, which meets the requirements of track detection.

    Research on Load Forecast of Ball Mill Based on PCA-PSO-SVM
    FENG Xianding,WEI Jingtao,WU Zhangyong,QIAN Jie,PU Youshang
    Electronic Science and Technology. 2022, 35(1):  29-34.  doi:10.16180/j.cnki.issn1007-7820.2022.01.005
    Abstract ( 95 )   HTML ( 3 )   PDF (842KB) ( 31 )  
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    As the main equipment in the grinding production, the internal load of the ball mill cannot be directly detected during operation. Therefore, it is difficult to effectively control the load in real time, which leads to the reduction of grinding efficiency. To solve this problem, the grinding sound signal of the ball mill is collected through the grinding experiment, and the signal is analyzed by the Welch power spectrum, and the relationship between the grinding sound spectrum information and the load of the ball mill is investigated in the proposed study. PCA is used to extract the features of the power spectrum to provide external feature information for load prediction of the ball mill. PSO is adopted to optimize the relevant parameters of SVM and the load prediction model of PA-PSO-SVM ball mill is established. Research shows that the prediction root mean square error of the ball mill prediction model is 1.144 3, the average absolute error is 0.912 5, and the average percentage error is 2.797 9%, which proves the effectiveness and stability of the model for predicting the load of the ball mill.

    Research on Occluded Face Recognition Method Based on Deep Learning
    CHENG Xiaoya,ZHANG Lei
    Electronic Science and Technology. 2022, 35(1):  35-39.  doi:10.16180/j.cnki.issn1007-7820.2022.01.006
    Abstract ( 447 )   HTML ( 31 )   PDF (1415KB) ( 67 )  
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    In view of the large amount of calculation in traditional CNN in occluded face recognition, this study proposes a new PCANet deep learning network for face recognition based on L1-2DPCA. The proposed network uses L1-2DPCA to learn filters of multiple convolutional layers. After the convolutional layer, pooling is performed through binary hashing and block-by-block histogram. CNN, PCANet, 2DPCANet and L1-PCANet are compared, and the proposed network is tested on AR and RMFD face data sets. The results show that in all tests, the recognition performance of the deep learning network proposed in this study is better than other networks. Due to the use of L1 norm, the proposed deep learning network has strong robustness to the changes of outliers and training images.

    Research on Fatigue Life of Oil Cylinder System Based on Multi-Body Dynamics and Finite Element
    SU Xiaohang,WANG Lihua,CHEN Jiaming
    Electronic Science and Technology. 2022, 35(1):  40-44.  doi:10.16180/j.cnki.issn1007-7820.2022.01.007
    Abstract ( 75 )   HTML ( 3 )   PDF (1535KB) ( 12 )  
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    In view of the fatigue life of the key components of the dynamic stabilization device, this study adopts the method based on multi-body dynamics and finite element method, and takes the clamp oil cylinder system of the dynamic stabilization device as the research object to conduct simulation analysis. This proposed method uses ADAMS software to perform multi-body dynamics analysis on the dynamic stabilization device to obtain the force load spectrum of the clamp cylinder system. Besides, the method imports the force load spectrum into the finite element software Ansys Workbench to perform transient dynamics of the clamp cylinder system analysis. According to the results of transient dynamics analysis, the fatigue life status of the clamp cylinder system is calculated using the fatigue analysis software NCODE. The simulation analysis results show that the weakest fatigue life of the clamp cylinder system is at its root, and the minimum number of cycles is 8.807×105.

    Aerodynamic Noise Analysis for High-Speed Train’s Pantograph and Study on Noise Reduction of the Cavity of Pantograph
    YUAN Xianpu,MIAO Xiaodan,YANG Jian,YUAN Tianchen,YUAN Ding
    Electronic Science and Technology. 2022, 35(1):  45-52.  doi:10.16180/j.cnki.issn1007-7820.2022.01.008
    Abstract ( 172 )   HTML ( 5 )   PDF (3787KB) ( 25 )  
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    In view of the increasing speed of high-speed trains and the increasing aerodynamic noise of the pantograph, LES large eddy simulation, boundary layer noise source model and FW-H acoustic analogy method are used to carry out numerical simulation by establishing a local 1:1 aerodynamic noise analysis model of a certain type of pantograph. The contribution of aerodynamic noise of each part of the pantograph is studied, and the noise reduction effect of the jet noise reduction method for the cavity of the larger noise position is explored. The results show that the numerical simulation accuracy is accurate when the number of grids is 43.23 million. The insulator upstream of the pantograph cavity and the middle of the cavity are the main sources of aerodynamic noise. Before and after the jet noise reduction, the internal aerodynamic noise is broadband noise, the main energy is concentrated in 0~4 500 Hz. The inclined jet noise reduction is performed on the cavity at a traveling speed of 250 km·h-1, and the minimum sound pressure level of the vertical monitoring point 25 m away from the train is 81.65 dB, which is 2.64 dB lower than that before noise reduction.

    Research on Mechanical Characteristics of Railway Bridge Ballast Bed Based on ADAMS
    CHEN Jiaming,WANG Lihua,SU Xiaohang
    Electronic Science and Technology. 2022, 35(1):  53-59.  doi:10.16180/j.cnki.issn1007-7820.2022.01.009
    Abstract ( 119 )   HTML ( 2 )   PDF (2177KB) ( 23 )  
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    This study uses software simulation to explore the mechanical characteristics of the ballast bed when the dynamic stabilization device is operating on the railway bridge. First, a three-dimensional solid diagram of each component of the stabilizer-track-bridge system in UG is established and assembled. Then, the solid diagram is imported into the ADAMS software through a specific format to complete the establishment of the system model. Finally, the dynamic simulation of the system model is carried out through ADAMS. The study also investigates the dynamic response of the sleeper when the stabilizer is operated at different excitation frequencies. On the basis of obtaining the optimal excitation frequency, the acceleration response of the track bed under different vertical downforce is studied, and the optimal operating parameters are obtained. ADAMS post-processing analysis results show that the track bed stabilizes after the dynamic stabilization device is operated on the railway bridge for 2.5 s. The greater the vertical downward pressure, the greater the sleeper lateral displacement, lateral velocity and lateral resistance response. The greater the excitation frequency, the lateral dynamic response of the sleeper increases first and then decreases,and the optimal excitation frequency of the stabilizer is 34 Hz. As the vertical downforce increases, the lateral and vertical accelerations of the track bed first increase and then decrease, and the longitudinal acceleration is basically unchanged,and the optimal vertical downforce is 120 kN.

    Operation Characteristics Analysis of Four-Poles Universal Motor Based on Maxwell
    SHANGGUAN Xuanfeng,LIU Yongjian,YANG Tingyu,WEI Jinsong
    Electronic Science and Technology. 2022, 35(1):  60-65.  doi:10.16180/j.cnki.issn1007-7820.2022.01.010
    Abstract ( 111 )   HTML ( 3 )   PDF (1257KB) ( 29 )  
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    In order to reduce the cost of the universal motor, a new four pole double brush universal motor is designed based on a pick motor. The motor has the advantages of short end of armature winding, reduced brush number, and no need of excitation winding for stator auxiliary magnetic pole, which can effectively reduce the material cost of the series motor. By improving the structure of the traditional two-poles series motor, the structural parameters of the new four-poles series motor are preliminarily determined, and the two-dimensional finite element model of the motor is established using Maxwell software. The mathematical model and air gap flux density of the new series motor are analyzed, and the operating characteristics and load performance of the motor are compared and analyzed. The results show that the four-poles series motor is superior to the original two-pole motor in terms of operating characteristics and load performance. The above findings provide a research basis for further optimization of the motor.

    Large-Disturbance Stability Analysis of DC Microgrid Based on Mixed Potential Function
    WANG Yumei,ZHANG Zihan,WANG Hao
    Electronic Science and Technology. 2022, 35(1):  66-72.  doi:10.16180/j.cnki.issn1007-7820.2022.01.011
    Abstract ( 189 )   HTML ( 8 )   PDF (1956KB) ( 64 )  
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    The constant power load in DC microgrid group presents negative impedance characteristics, which will adversely affect the stability of DC microgrid group. Therefore, it is necessary to analyze the stability power limit of DC microgrid group. In order to solve the problem, this study uses a mixed potential function to analyze the large-signal stability of a DC microgrid group with a constant power load. According to the characteristics of the DC-DC converters connected between the sub-microgrids, the DC microgrid group is equivalent to a sub-microgrid and a controlled current source in parallel, so as to establish the large signal equivalent circuit diagram of the DC microgrid group. The large-signal stability criterion of the DC microgrid group is derived from the mixed potential function theory, and the stability analysis is carried out according to the criterion. Verification by MATLAB/Simulink proves that the DC microgrid group can maintain stable operation if it meets the stability criterion after the constant power load increases.

    Active Disturbance Rejection Control of VSR under Unbalanced Grid Voltage Based on Firefly Optimization Algorithm
    YAO Qiang,ZENG Guohui,HUANG Bo,LIU Jin,WEI Yu
    Electronic Science and Technology. 2022, 35(1):  73-79.  doi:10.16180/j.cnki.issn1007-7820.2022.01.012
    Abstract ( 83 )   HTML ( 3 )   PDF (1133KB) ( 14 )  
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    Under the traditional control mode, the grid-side current harmonics of three-phase VSR are large when the grid voltage is unbalanced, and its dynamic performance is easily affected by load disturbance. In view of this problem, an active disturbance rejection control strategy based on firefly optimization algorithm is proposed. The active disturbance rejection controller which is not related to the object model is added to the inner current loop of the system to perform closed-loop control to initiatively compensate and restrain the internal and external isturbances of the system in time. At the same time, the firefly optimization algorithm is adopted to optimize the key parameters of the ADRC. The algorithm has a faster convergence speed while searching for the optimal value of the objective function globally, which improves the control performance of the system. The simulation results show that compared with the traditional control method, the total harmonic distortion rate of the grid-side current is reduced by 3.67% and the anti-load disturbance ability of the rectifier is effectively improved, which verifies the correctness and effectiveness of the control strategy.

    Control Strategy of Modular Multilevel Converter Under Unbalanced Grid Voltage
    NIU Shuaichen,WANG Fuzhong,HAN Yaofei,HE Guofeng,NIU Yeke
    Electronic Science and Technology. 2022, 35(1):  80-86.  doi:10.16180/j.cnki.issn1007-7820.2022.01.013
    Abstract ( 100 )   HTML ( 4 )   PDF (1743KB) ( 70 )  
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    When the power grid is in a voltage unbalanced state, a circulating current will be generated inside the MMC. The positive sequence, negative sequence and zero sequence components of double frequency exist in the circulating current, which increases the instability of the system. In view of the problem of MMC double-frequency circulating current suppression under unbalanced power grids, this study proposes a circulating current suppression strategy based on a linear active disturbance rejection controller. According to the instantaneous power theory, the quantitative relationship of the circulating current parameters is derived. On this basis, the circulating current controller based on the linear active disturbance rejection control strategy is designed to suppress the circulating current. Finally, the proposed control strategy is simulated by MATLAB/Simulink software. The simulation results show that the control strategy can effectively restrain the circulation and increase the stability of the system.

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