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Novel Single Switch DC-DC Converter for High Step-Up Conversion Ratio
Hu, Xuefeng,Gao, Benbao,Huang, Yuanyuan,Chen, Hao The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
This paper presents a new structure for a step up dc-dc converter, which has several advantageous features. Firstly, the input dc source and the clamped capacitor are connected in series to transfer energy to the load through dual voltage multiplier cells. Therefore, the proposed converter can produce a very high voltage and a high conversion efficiency. Secondly, a double voltage clamped circuit is introduced to the primary side of the coupled inductor. The energy of the leakage inductance of the coupled inductor is recycled and the inrush current problem of the clamped circuits can be shared equally by two synchronous clamped capacitors. Therefore, the voltage spike of the switch tube is solved and the current stress of the diode is reduced. Thirdly, dual voltage multiplier cells can absorb the leakage inductance energy of the secondary side of the coupled inductor to obtain a higher efficiency. Fourthly, the active switch turns on at almost zero current and the reverse-recovery problem of the diodes is alleviated due to the leakage inductance, which further improves the conversion efficiency. The operating principles and a steady-state analysis of the continuous, discontinuous and boundary conduction modes are discussed in detail. Finally, the validity of this topology is confirmed by experimental results.
Hu, Xuefeng,Zhang, Meng,Li, Yongchao,Li, Linpeng,Wu, Guiyang The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3
This paper presents a ripple-free input current modified interleaved boost converter for high step-up applications. By integrating dual coupled inductors and voltage multiplier techniques, the proposed converter can reach a high step-up gain without an extremely high turn-ON period. In addition, a very small auxiliary inductor employed in series to the input dc source makes the input current ripple theoretically decreased to zero, which simplifies the design of the electromagnetic interference (EMI) filter. In addition, the voltage stresses on the semiconductor devices of the proposed converter are efficiently reduced, which makes high performance MOSFETs with low voltage rated and low resistance $r_{DS}$(ON) available to reduce the cost and conduction loss. The operating principles and steady-state analyses of the proposed converter are introduced in detail. Finally, a prototype circuit rated at 400W with a 42-50V input voltage and a 400V output voltage is built and tested to verify the effectiveness of theoretical analysis. Experimental results show that an efficiency of 95.3% can be achieved.
Xuefeng Hu,Meng Zhang,Yongchao Li,Linpeng Li,Guiyang Wu 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3
This paper presents a ripple-free input current modified interleaved boost converter for high step-up applications. By integrating dual coupled inductors and voltage multiplier techniques, the proposed converter can reach a high step-up gain without an extremely high turn-ON period. In addition, a very small auxiliary inductor employed in series to the input dc source makes the input current ripple theoretically decreased to zero, which simplifies the design of the electromagnetic interference (EMI) filter. In addition, the voltage stresses on the semiconductor devices of the proposed converter are efficiently reduced, which makes high performance MOSFETs with low voltage rated and low resistance rDS(ON) available to reduce the cost and conduction loss. The operating principles and steady-state analyses of the proposed converter are introduced in detail. Finally, a prototype circuit rated at 400W with a 42-50V input voltage and a 400V output voltage is built and tested to verify the effectiveness of theoretical analysis. Experimental results show that an efficiency of 95.3% can be achieved.
Novel Single Switch DC-DC Converter for High Step-Up Conversion Ratio
Xuefeng Hu,Benbao Gao,Yuanyuan Huang,Hao Chen 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3
This paper presents a new structure for a step up dc-dc converter, which has several advantageous features. Firstly, the input dc source and the clamped capacitor are connected in series to transfer energy to the load through dual voltage multiplier cells. Therefore, the proposed converter can produce a very high voltage and a high conversion efficiency. Secondly, a double voltage clamped circuit is introduced to the primary side of the coupled inductor. The energy of the leakage inductance of the coupled inductor is recycled and the inrush current problem of the clamped circuits can be shared equally by two synchronous clamped capacitors. Therefore, the voltage spike of the switch tube is solved and the current stress of the diode is reduced. Thirdly, dual voltage multiplier cells can absorb the leakage inductance energy of the secondary side of the coupled inductor to obtain a higher efficiency. Fourthly, the active switch turns on at almost zero current and the reverse-recovery problem of the diodes is alleviated due to the leakage inductance, which further improves the conversion efficiency. The operating principles and a steady-state analysis of the continuous, discontinuous and boundary conduction modes are discussed in detail. Finally, the validity of this topology is confirmed by experimental results.
Qianqian Hu,Xian-Lei Shi,Yongju Chen,Xuefeng Han,Peigao Duan,Wenqin Zhang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-
A universal fiber catalyst for the Knoevenagel condensations is presented. The detailed characterization by mechanical properties, elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber catalyst during the full-course. Moreover, the mediated condensations proceeded smoothly with lower catalyst amount (1 mol%) in different solvents of varying polarities and the products were obtained in good to excellent yields (95–99%), and even with water as the solvent could also achieve a series of a,b-unsaturated compounds with nearly quantitative yields at room temperature. Furthermore, the catalyst exhibited excellent flexibility and could be easily recovered and recycled with prominent stability over 10 cycles, and the procedure was operationally convenient and effectively amenable to the gram scale on a simple fixed-bed reactor.
Ke Tao,Ming Li,Xuefeng Gu,Ming Wang,Tianwei Qian,Lijun Hu,Jiang Li 대한약리학회 2022 The Korean Journal of Physiology & Pharmacology Vol.26 No.5
Abdominal aortic aneurysm (AAA) is a life-threatening disorder worldwide. Fibroblast growth factor 21 (FGF21) was shown to display a high level in the plasma of patients with AAA; however, its detailed functions underlying AAA pathogenesis are unclear. An in vitro AAA model was established in human aortic vascular smooth muscle cells (HASMCs) by angiotensin II (Ang-II) stimulation. Cell counting kit-8, wound healing, and Transwell assays were utilized for measuring cell proliferation and migration. RT-qPCR was used for detecting mRNA expression of FGF21 and activating transcription factor 4 (ATF4). Western blotting was utilized for assessing protein levels of FGF21, ATF4, and markers for the contractile phenotype of HASMCs. ChIP and luciferase reporter assays were implemented for identifying the binding relation between AFT4 and FGF21 promoters. FGF21 and ATF4 were both upregulated in Ang-II-treated HASMCs. Knocking down FGF21 attenuated Ang-IIinduced proliferation, migration, and phenotype switch of HASMCs. ATF4 activated FGF21 transcription by binding to its promoter. FGF21 overexpression reversed AFT4 silencing-mediated inhibition of cell proliferation, migration, and phenotype switch. ATF4 transcriptionally upregulates FGF21 to promote the proliferation, migration, and phenotype switch of Ang-II-treated HASMCs.
Dual input step‑up inverter with low leakage current for PV generation applications
Kunshu Mu,Chenjin Fei,Xuefeng Hu,Han Xu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12
The non-isolated inverter has been widely used in photovoltaic generation applications due to its low cost, reduced size, low weight, and high efficiency. However, when there is no galvanic isolation between the photovoltaic (PV) plant and the grid, leakage current may be generated due to the parasitic capacitor to the ground of the photovoltaic (PV) plant, which brings electromagnetic interference (EMI) and security problems. The main idea of this article is to construct a step-up voltage source inverter with two low-voltage input sources. The proposed inverter integrates a step-up dc–dc converter and a modified step-up dc–dc converter that has the advantages of a simple structure and strong voltage boosting capability. Moreover, the negative polarity of a solar cell and the neutral point of a power grid are linked together, which can greatly reduce the leakage current and improve the reliability and efficiency of the PV system. The operating principle, modulation strategy, and static behavior of the proposed inverter are described in detail. To verify the effectiveness of the proposed structure, a 250w laboratory test setup is established, and test results have been shown.