A Phase-Shift Modulation Strategy for a Bidirectional CLLC Resonant Converter

Wenmin Hua,Hongfei Wu,Zhiyuan Yu,Yan Xing,Kai Sun 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

A novel phase-shift modulation strategy is applied to a bidirectional CLLC resonant converter (RC). Different from the well-known pulse-frequency modulation strategy, the switching frequency of the CLLC RC is constant, which is beneficial for optimal design and control of the converter. Theoretical analysis proves that voltage gain is independent on load and resonant tank. As a result, topology is optimized with ensuring symmetry of converter. Simulation model is built in Simulink and a 1kW prototype is made. Simulation and experimental results verify the voltage transfer ratio. Dynamic response with load stepping up and down is stable and rapid. In addition, soft-switching of all the power switches can be achieved to reduce switching losses and improve efficiency. Detailed operation principles and characteristics of the modulation strategy are analyzed and verified with experimental results.

Resonant Tank Design Considerations and Implementation of a LLC Resonant Converter with a Wide Battery Voltage Range

Sun, Wenjin,Wu, Hongfei,Hu, Haibing,Xing, Yan The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

This paper illustrates resonant tank design considerations and the implementation of a LLC resonant converter with a wide battery voltage range based on the fundamental harmonic approximation (FHA) analysis. Unlike the conventional design at zero load, the parameter K (the ratio of the transformer magnetizing inductor L_m to the resonant inductor L_r) of the LLC converter in this paper is designed with two charging points, (V_{o_min}, I_{o_max1}) and (V_{o_max}, I_{o_max2}), according to the battery charging strategy. A 2.9kW prototype with an output voltage range of 36V to 72V dc is built to verify the design. It achieves a peak efficiency of 96%.

A Novel Dual-Input Boost-Buck Converter with Coupled Inductors for Distributed Thermoelectric Generation Systems

Zhang, Junjun,Wu, Hongfei,Sun, Kai,Xing, Yan,Cao, Feng The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4

A dual-input boost-buck converter with coupled inductors (DIBBC-CI) is proposed as a thermoelectric generator (TEG) power conditioner with a wide input voltage range. The DIBBC-CI is built by cascading two boost cells and a buck cell with shared inverse coupled filter inductors. Low current ripple on both sides of the TEG and the battery are achieved. Reduced size and power losses of the filter inductors are benefited from the DC magnetic flux cancellation in the inductor core, leading to high efficiency and high power density. The operational principle, impact of coupled inductors, and design considerations for the proposed converter are analyzed in detail. Distributed maximum power point tracking, battery charging, and output control are implemented using a competitive logic to ensure seamless switching among operational modes. Both the simulation and experimental results verify the feasibility of the proposed topology and control.

A Novel Dual-Input Boost-Buck Converter with Coupled Inductors for Distributed Thermoelectric Generation Systems

Junjun Zhang,Hongfei Wu,Kai Sun,Yan Xing,Feng Cao 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4

A dual-input boost-buck converter with coupled inductors (DIBBC-CI) is proposed as a thermoelectric generator (TEG) power conditioner with a wide input voltage range. The DIBBC-CI is built by cascading two boost cells and a buck cell with shared inverse coupled filter inductors. Low current ripple on both sides of the TEG and the battery are achieved. Reduced size and power losses of the filter inductors are benefited from the DC magnetic flux cancellation in the inductor core, leading to high efficiency and high power density. The operational principle, impact of coupled inductors, and design considerations for the proposed converter are analyzed in detail. Distributed maximum power point tracking, battery charging, and output control are implemented using a competitive logic to ensure seamless switching among operational modes. Both the simulation and experimental results verify the feasibility of the proposed topology and control.

Resonant Tank Design Considerations and Implementation of a LLC Resonant Converter with a Wide Battery Voltage Range

Wenjin Sun,Hongfei Wu,Haibing Hu,Yan Xing 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

This paper illustrates resonant tank design considerations and the implementation of a LLC resonant converter with a wide battery voltage range based on the fundamental harmonic approximation (FHA) analysis. Unlike the conventional design at zero load, the parameter K (the ratio of the transformer magnetizing inductor Lm to the resonant inductor Lr) of the LLC converter in this paper is designed with two charging points, (Vo_min, Io_max1) and (Vo_max, Io_max2), according to the battery charging strategy. A 2.9kW prototype with an output voltage range of 36V to 72V dc is built to verify the design. It achieves a peak efficiency of 96%.

An Improved LLC Resonant Converter with Variable-Rectifier for Electric-Vehicle Charger Application

Jian Zhao,Xinxi Tang,Hongfei Wu,Yan Xing,Kai Sun 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

An improved LLC converter with variablerectifier (VR) is studied and evaluated for electric-vehicle charger applications with wide output voltage range. The VR can be reconfigured as center-tapped rectifier (CTR) and full-bridge rectifier (FBR) by the secondary side auxiliary switches. The output voltage range is extended by changing the configuration of rectifier, which results in reduced switching frequency range, circulating current, and conduction losses. Meanwhile, zero voltage switching are achieved for all MOSFETs. A mode transition scheme is employed to achieve smooth and fast transition between CTR and FBR modes. The operation principles are analyzed in detail. A 500W prototype with 400V input voltage and 40-160V output voltage is built and tested to verify the feasibility of the converter.

Surface Modification of Cellulose Microcrystalline with Aluminate Coupling Agent and Its Effects on Flame Retardant and Mechanical Properties of Epoxy Resin

Minghang Wang,Quan Wu,Zhengyu Feng,Xiaoyu Gu,Hongfei Li,Jun Sun,Bin Fei,Sheng Zhang 한국섬유공학회 2020 Fibers and polymers Vol.21 No.10

Cellulose microcrystalline (CMC), a linear polysaccharide with glucosidic bond, was successfully extracted frombamboo powder and modified by aluminate coupling agent (ACA) to prepare ACA-CMC. The chemical structure of asdesignedACA-CMC was characterized by scanning electron microscopy and Fourier transform infrared spectra. ACACMC,in association with ammonium polyphosphate (APP), was introduced into epoxy resin (EP) by casting process toobtain flame-resistant composites. The fire performance evaluation indicated that the presence of 10 phr APP and 5 phrACA-CMC in EP achieved the maximal LOI value of 29.0 %, passed the UL-94 V-0 rating, and significantly decreased thepeak heat release rate from 1055 kW·m-2 of neat EP to 294 kW·m-2. The introduction of ACA-CMC could also improve themechanical properties of EP composites due to the strengthening effect of CMC and better interfacial compatibility aftermodification with ACA. Moreover, the relative mechanisms were also proposed.

Family of Dual-Input Dual-Buck Inverters Based on Dual-Input Switching Cells

Yang, Fan,Ge, Hongjuan,Yang, Jingfan,Dang, Runyun,Wu, Hongfei The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

A family of dual-DC-input (DI) dual-buck inverters (DBIs) is proposed by employing a DI switching cell as the input of traditional DBIs. Three power ports, i.e. a low voltage DC input port, a high voltage DC input port and an AC output port, are provided by the proposed DI-DBIs. A low voltage DC source, whose voltage is lower than the peak amplitude of the AC side voltage, can be directly connected to the DI-DBI. This supplies power to the AC side in single-stage power conversion. When compared with traditional DBI-based two-stage DC/AC power systems, the conversion stages are reduced, and the power rating and power losses of the front-end Boost converter of the DI-DBI are reduced. In addition, five voltage-levels are generated with the help of the two DC input ports, which is a benefit in terms of reducing the voltage stresses and switching losses of switches. The topology derivation method, operation principles, modulation strategy and characteristics of the proposed inverter are analyzed in-depth. Experimental results are provided to verify the effectiveness and feasibility of the proposed DI-DBIs.

Family of Dual-Input Dual-Buck Inverters Based on Dual-Input Switching Cells

Fan Yang,Hongjuan Ge,Jingfan Yang,Runyun Dang,Hongfei Wu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

A family of dual-DC-input (DI) dual-buck inverters (DBIs) is proposed by employing a DI switching cell as the input of traditional DBIs. Three power ports, i.e. a low voltage DC input port, a high voltage DC input port and an AC output port, are provided by the proposed DI-DBIs. A low voltage DC source, whose voltage is lower than the peak amplitude of the AC side voltage, can be directly connected to the DI-DBI. This supplies power to the AC side in single-stage power conversion. When compared with traditional DBI-based two-stage DC/AC power systems, the conversion stages are reduced, and the power rating and power losses of the front-end Boost converter of the DI-DBI are reduced. In addition, five voltage-levels are generated with the help of the two DC input ports, which is a benefit in terms of reducing the voltage stresses and switching losses of switches. The topology derivation method, operation principles, modulation strategy and characteristics of the proposed inverter are analyzed in-depth. Experimental results are provided to verify the effectiveness and feasibility of the proposed DI-DBIs.

Genomic characterization and pathogenic study of two porcine reproductive and respiratory syndrome viruses with different virulence in Fujian, China

Xiukun Sui,Ting Xin,Xiaoyu Guo,Hong Jia,Ming Li,Xintao Gao,Jing Wu,Yitong Jiang,L.Willems2,Hongfei Zhu,Shaohua Hou 대한수의학회 2018 Journal of Veterinary Science Vol.19 No.3

Two strains of porcine reproductive and respiratory syndrome virus (PRRSV) were isolated in 2006 and 2016 and designated as FZ06A and FZ16A, respectively. Inoculation experiments showed that FZ06A caused 100% morbidity and 60% mortality, while FZ16A caused 100% morbidity without death. By using genomic sequence and phylogenetic analyses, close relationships between a Chinese highly pathogenic PRRSV strain and the FZ06A and FZ16A strains were observed. Based on the achieved results, multiple genomic variations in Nsp2, a unique N-glycosylation site (N33→K33), and a K151 amino acid (AA) substitution for virulence in the GP5 of FZ16A were detected; except the 30 AA deletion in the Nsp2-coding region. Inoculation experiments were conducted and weaker virulence of FZ16A than FZ06A was observed. Based on our results, a 30 AA deletion in the Nsp2-coding region is an unreliable genomic indicator of a high virulence PRRSV strain. The Nsp2 and GP5 differences, in addition to the virulence difference between these two highly pathogenic PRRSV strains, have the potential to be used to establish a basis for further study of PRRSV virulence determinants and to provide data useful in the development of vaccines against this economically devastating disease.