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Wide input range non‑isolated three‑port converters for stand‑alone PV storage power systems
Shengwei Gao,Qingtong Zhu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.2
To address the instability of the input voltage of photovoltaic (PV) in a stand-alone PV storage power generation system, a wide input range non-isolated three-port converter that can operate in a range that is greater than and less than the voltage of the storage port is proposed in this paper. The proposed converter can realize the energy flow and power balance between the PV, the battery, and the load. This converter is a combination of conventional Buck, Boost, and Buck–Boost converters with a four-switch bi-directional Buck–Boost converter (FSBB). The FSBB is used to connect the PV and battery ports, which can reduce the voltage constraint of the storage port on the PV port voltage, and broaden the selection of the voltage levels of the storage port to meet the application requirements of the PV port with a wide voltage input. In this paper, an experimental prototype is designed by combining the Boost converter and the FSBB converter. Finally, the correctness of the theoretical analysis and the feasibility of the energy management strategy of the converter are verified through experimental results.
C-Band Synthetic Aperture Microwave Radiometer and Its Imaging Experiments
Shengwei, Zhang,Xiaolong, Dong,Ji, Wu,Jingshan, Jiang,Shifeng, Zheng 대한원격탐사학회 2001 International Symposium on Remote Sensing Vol.17 No.1
The principles of the interferometric synthetic aperture was been briefly introduced, the system design of a C-band microwave interferometric synthetic aperture radiometer is presented. This systemhas a 6-element thinned array with 11 analog complex correlator to obtain the 11 visibility function spatial- frequency terns, which result in 22 digitally synthesizedspatial resolution cell. So the synthetic apertureradiometer have a spatial resolution as high as one 22nd of that corresponding to one antenna element. Thesynthetic radiometer has a real aperture resolution cell in the along-hack direction and has 22 synthetic apertureresolution cells in the cross-track direction. Finally, the results of imaging experiments are given.
Design and Implementation of Location and Activity Monitoring System Based on LoRa
( Shengwei Lin ),( Ziqiang Ying ),( Kan Zheng ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.4
The location and human activity are usually used as one of the important parameters to monitor the health status in healthcare devices. However, nearly all existing location and monitoring systems have the limitation of short-range communication and high power consumption. In this paper, we propose a new mechanism to collect and transmit monitoring information based on LoRa technology. The monitoring device with sensors can collect the real-time activity and location information and transmit them to the cloud server through LoRa gateway. The user can check all his history and current information through the specific designed mobile applications. Experiment was carried out to verify the communication, power consumption and monitoring performance of the entire system. Experimental results demonstrate that this system can collect monitoring and activity information accurately and provide the long rang coverage with low power consumption.
Shengwei Zhang,Lihong Cai,Thi Anh Nguyet Nguyen,Meiling Geng,Kun Gao,Sung-Tae Hong,Moon-Jo Kim 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.2
Aluminum clad steel (ACS) sheets are heat treated by electrically assisted rapid heat treatment (subsecond duration) to balance their strength and ductility. The results of microstructural analysis show that the electric current results in the formation of different intermetallic compounds (IMCs) attributed to the rapid heating and the athermal effect of the electric current. The different IMCs affect the interfacial bonding strength and the mechanical properties of the ACS sheet. The tensile tests suggest that the yield strength of the ACS sheet gradually decreases, while the elongation gradually increases up to the current density of 170 A/mm2. In contrast, a higher current density of 190 A/mm2 dramatically increases the thickness of the IMC layer, resulting in premature fracture of the ACS sheet due to early interfacial debonding. The fracture mechanism is found to be a matrix-dominated fracture or interfacial IMC-dominated fracture depending on the applied current density. Moreover, the U-shape forming test confirms that the enhanced interfacial bonding strength and favorable formability of the ACS sheet can be achieved by repeatedly applying the electric pulses of 170 A/mm2 four times rather than using the single electric pulse of 190 A/mm2 due to the formation of a thick IMC layer under the high current density of 190 A/mm2. The present study proves that the electrically assisted rapid heat treatment is an efficient method to balance the strength and formability of the ACS sheet.
Complete loss distribution model of GaN HEMTs considering the influence of parasitic parameters
Shengwei Gao,Jinrui Tian,Xiaoyu Fu,Yongxiao Li,Bo Wang,Lixia Zhao 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.1
When compared with Si-based devices, Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) possess the advantages of lower junction-to-case thermal resistance, smaller on-state resistance, faster switching velocity, and higher switching frequency. These advantages make them a promising power semiconductor device. However, with the enhancement of switching frequencies, the influence of parasitic parameters on switching ringing and the losses of GaN HEMTs are increasingly severe. Thus, it is necessary to predict the loss distribution by establishing an accurate loss model of the switching process. On the premise of considering parasitic inductance, nonlinear junction capacitance, and reverse transfer characteristics, this article proposes a precise switching loss model of GaN HEMTs to predict the loss distribution in the switching process. In addition, it verifies results based on the double pulse test (DPT) circuit, which validates the accuracy of the proposed model. Ultimately, based on the above-mentioned loss model, this article discussed the influence of parasitic capacitance and inductance on the output capacitance loss (Eqoss), the reverse conduction loss (ESD), the opening V-I overlap loss (Eopen), the closing V-I overlap loss (Eclose), and the total loss (Etotal). Then, this article produces an optimizing method to enhance the conversion efficiency of GaN HEMTs in accordance with laboratory findings.
Yamin Li,Shengwei Sun 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-
Organic fouling was one of the most fatal weakness for membranes applied in water treatment. Aiming atovercoming the defect of liable to contamination and achieving efficient circulation and long-term stableoperation, it was reported a kind of multilayer-loaded hydrogels membranes with superior antifoulingproperty. Hydrogel coating mixture were coated onto PES substrate layer by layer and then crosslinkedby ambient free radical blending polymerization reaction endowing the membrane with interpenetratingnetwork structure and super hydrophilic surface. The FT-IR, FESEM, and AFM were used to characterthe structure and morphology of obtained membranes. Dynamic contact Angle, BET and membraneperformance evaluation instrument were used to evaluate the membrane performance. Compared withquantitative single layer-coated membrane, the four layers-coated hydrogel membrane exhibited moreexcellent and stable performance in terms of flux, rejection and fouling resistance. In particular, the waterflux of the four layers-coated hydrogel membrane increased by about 25%. When 0.5 g/L BSA was selectedas simulated protein contamination liquid, flux recovery rate (FRR) of four layers-coated hydrogel membraneswas up to 86.33%, indicating excellent long-term tolerance and resistance to proteins. It must bepointed out that four layers were the maximum loading number of the ambient self-crosslinking hydrogelCQAS casting solution within the limit air-cured time. On the whole, the multi-layer coated hydrogelmembranes showed practical application value in the field of water treatment.
Recursive Design of Nonlinear Disturbance Attenuation Control for STATCOM
Feng Liu,Shengwei Mei,Qiang Lu,Masuo Goto 대한전기학회 2005 International Journal of Control, Automation, and Vol.3 No.2
In this paper, a nonlinear robust control approach is applied to design a controller for the Static Synchronous Compensator (STATCOM). A robust control dynamic model of STATCOM in a one-machine, infinite-bus system is established with consideration of the torque disturbance acting on the rotating shaft of the generator set and the disturbance to the output voltage of STATCOM. A novel recursive approach is utilized to construct the energy storage function of the system such that the solution to the disturbance attenuation control problem is acquired, which avoids the difficulty involved in solving the Hamilton-Jacobi-Issacs (HJI) inequality. Sequentially, the nonlinear disturbance attenuation control strategy of STATCOM is obtained. Simulation results demonstrate that STATCOM with the proposed controller can more effectively improve the voltage stability, damp the oscillation, and enhance the transient stability of power systems compared to the conventional PI+PSS controller.
Study of Spaceborne W-band Millimeter Wave Radiometer
Jing, Li,Shengwei, Zhang,Maohua, Sun,Decai, Kong,Heguang, Liu,Jingshan, Jiang 대한원격탐사학회 2001 International Symposium on Remote Sensing Vol.17 No.1
The W-band millimeter wave radiometer has been studied under the support of Chinese Academy of Science (CAS) and it is successfully studied for the first time in China. Its technical index is suitable for the use in space. The main characteristics of the W-band millimeter wave radiometer are introduced in this paper.