A Dual Buck Three-Level PV Grid-Connected Inverter

Baojian Ji,Feng Hong,Jianhua Wang,Shengming Huang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4

The use of a PV grid-connected inverter with non-isolated topology and without a transformer is good for improving conversion efficiency; however, this inverter has become increasingly complicated for eliminating leakage current. To simplify the complicated architecture of traditional three-level dual buck inverters, a new dual Buck three-level PV grid-connected inverter topology is proposed. In the proposed topology, the voltage on the grounding stray capacitor is clamped by large input capacitors and is equal to half of the bus voltage; thus, leakage current can be eliminated. Unlike in the traditional topology, the current in the proposed topology passes through few elements and does not flow through the body diodes of MOSFET switches, resulting in increased efficiency. Additionally, a multi-loop control method that includes voltage-balancing control is proposed and analyzed. Both simulation and experimental results are demonstrated to verify the proposed structure and control method.

A Dual Buck Three-Level PV Grid-Connected Inverter

Ji, Baojian,Hong, Feng,Wang, Jianhua,Huang, Shengming The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4

The use of a PV grid-connected inverter with non-isolated topology and without a transformer is good for improving conversion efficiency; however, this inverter has become increasingly complicated for eliminating leakage current. To simplify the complicated architecture of traditional three-level dual buck inverters, a new dual Buck three-level PV grid-connected inverter topology is proposed. In the proposed topology, the voltage on the grounding stray capacitor is clamped by large input capacitors and is equal to half of the bus voltage; thus, leakage current can be eliminated. Unlike in the traditional topology, the current in the proposed topology passes through few elements and does not flow through the body diodes of MOSFET switches, resulting in increased efficiency. Additionally, a multi-loop control method that includes voltage-balancing control is proposed and analyzed. Both simulation and experimental results are demonstrated to verify the proposed structure and control method.

A Family of Non-Isolated Photovoltaic Grid Connected Inverters without Leakage Current Issues

Ji, Baojian,Wang, Jianhua,Hong, Feng,Huang, Shengming The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4

Transformerless solar inverters have a higher efficiency than those with an isolation link. However, they suffer from a leakage current issue. This paper proposes a family of single phase six-switch transformerless inverter topologies with an ac bypass circuit to solve the leakage current problem. These circuits embed two unidirectional freewheeling current units into the midpoint of a full bridge inverter, to obtain a freewheeling current path, which separates the solar panel from the grid in the freewheeling state. The freewheeling current path contains significantly fewer devices and poor performance body diodes are not involved, leading to a higher efficiency. Meanwhile, it is not necessary to add a voltage balancing control method when compared with the half bridge inverter. Simulation and experiments are provided to validate the proposed topologies.

A Family of Non-Isolated Photovoltaic Grid Connected Inverters without Leakage Current Issues

Baojian Ji,Jianhua Wang,Feng Hong,Shengming Huang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4

Transformerless solar inverters have a higher efficiency than those with an isolation link. However, they suffer from a leakage current issue. This paper proposes a family of single phase six-switch transformerless inverter topologies with an ac bypass circuit to solve the leakage current problem. These circuits embed two unidirectional freewheeling current units into the midpoint of a full bridge inverter, to obtain a freewheeling current path, which separates the solar panel from the grid in the freewheeling state. The freewheeling current path contains significantly fewer devices and poor performance body diodes are not involved, leading to a higher efficiency. Meanwhile, it is not necessary to add a voltage balancing control method when compared with the half bridge inverter. Simulation and experiments are provided to validate the proposed topologies.

An Inherent Zero-Voltage and Zero-Current-Switching Full-Bridge Converter with No Additional Auxiliary Circuits

Wang, Jianhua,Ji, Baojian,Wang, Hongbo,Chen, Naifu,You, Jun The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

An inherent zero-voltage and zero-current-switching phase-shifted full-bridge converter with reverse-blocking insulated-gate bipolar transistor (IGBT) or non-punch-through IGBT is proposed in this paper. This converter not only ensures that the switches in the lagging leg works at zero-current switching, but also minimizes circulating conduction loss without any additional auxiliary circuits. A 1.2 kW hardware prototype is designed, fabricated, and tested to verify the proposed topology. The control loop design procedures with small-signal models are also presented. A simple, low-cost, and robust democratic current-sharing circuit is also introduced and verified in this study. The proposed converter is a suitable alternative for compact, cost-effective applications with high-voltage input.

An Inherent Zero-Voltage and Zero-Current-Switching Full-Bridge Converter with No Additional Auxiliary Circuits

Jianhua Wang,Baojian Ji,Hongbo Wang,Naifu Chen,Jun You 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

An inherent zero-voltage and zero-current-switching phase-shifted full-bridge converter with reverse-blocking insulated-gate bipolar transistor (IGBT) or non-punch-through IGBT is proposed in this paper. This converter not only ensures that the switches in the lagging leg works at zero-current switching, but also minimizes circulating conduction loss without any additional auxiliary circuits. A 1.2 kW hardware prototype is designed, fabricated, and tested to verify the proposed topology. The control loop design procedures with small-signal models are also presented. A simple, low-cost, and robust democratic current-sharing circuit is also introduced and verified in this study. The proposed converter is a suitable alternative for compact, cost-effective applications with high-voltage input.

A Passive Lossless Soft-Switching Single Inductor Dual Buck Full-Bridge Inverter

Hong, Feng,Wu, Yu,Ye, Zunjing,Ji, Baojian,Zhou, Yufei The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

A novel passive lossless soft-switching single inductor dual buck full-bridge inverter (PLSSIDBFBI) is presented in this paper. To accomplish this, a passive lossless snubber circuit is added to a dual buck full-bridge inverter. Therefore, the advantages of the dual buck full-bridge inverter are included in the proposed inverter, and the inverter has just one filter inductor, which can decrease the system volume and improve the integration. In addition, the passive lossless snubber circuit achieves soft-switching by its own resonance, and all of the energy stored in the passive lossless snubber circuit can be transferred to load. A comparison between eight topologies is performed in this paper, and the analysis shows that the proposed soft-switching inverter topology has high reliability and efficiency. Finally, experimental results obtained with a 1 kW prototype verify the theoretical analysis and demonstrate the prominent characteristics of a reduced switching loss and improved efficiency.

A Usability Test for Dr. Liver, a 3D Virtual Liver Surgical Planning System

Xiaopeng Yang,Younggeun Choi,Wonsup Lee,Baojian Wang,Jaedo Yang,Hongpil Hwang,Ji Hyun Kim,Jisoo Song,Hee Chul Yu,Baik Hwan Cho,Heecheon You 대한인간공학회 2013 대한인간공학회 학술대회논문집 Vol.2013 No.5

A usability test was performed for a 3D virtual liver surgical planning system, named Dr. Liver. The system consists of five modules including (1) (1) Liver Extraction, (2) Vessel Extraction, (3) Tumor Extraction, (4) Liver Segmentation, and (5) Liver Surgery Planning. Various performance and preference measures were applied and opinions of the participants regarding likes, dislikes, and suggestions were collected. Three medical doctors participated in the usability test, consisting of five test modules. The system received a high score of satisfaction (mean = 6.5, S.D. = 0.8) as measured using a 7-point Likert scale throughout the five test modules. Based on the evaluation results, recommendations were made for better usability of the system. The present study would help practitioners to evaluate the usability of a system and identify potential usability problems in a systematic manner.

A Passive Lossless Soft-Switching Single Inductor Dual Buck Full-Bridge Inverter

Feng Hong,Yu Wu,Zunjing Ye,Baojian Ji,Yufei Zhou 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

A novel passive lossless soft-switching single inductor dual buck full-bridge inverter (PLSSIDBFBI) is presented in this paper. To accomplish this, a passive lossless snubber circuit is added to a dual buck full-bridge inverter. Therefore, the advantages of the dual buck full-bridge inverter are included in the proposed inverter, and the inverter has just one filter inductor, which can decrease the system volume and improve the integration. In addition, the passive lossless snubber circuit achieves soft-switching by its own resonance, and all of the energy stored in the passive lossless snubber circuit can be transferred to load. A comparison between eight topologies is performed in this paper, and the analysis shows that the proposed soft-switching inverter topology has high reliability and efficiency. Finally, experimental results obtained with a 1 kW prototype verify the theoretical analysis and demonstrate the prominent characteristics of a reduced switching loss and improved efficiency.