A Novel Circuit for Characteristics Measurement of SiC Transistors

Guoen Cao,Hee-Jun Kim 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.4

This paper proposes a novel test circuit for SiC transistors. On-state resistance under practical application conditions is an important characteristic for the device reliability and conduction efficiency of SiC transistors. In order to measure the on-state resistance in practical applications, high voltage is needed, and high current is also necessary to ignite performance for the devices. A softswitching circuit based on synchronous buck topology is developed in this paper. To provide highvoltage and high-current stresses for the devices without additional spikes and oscillations, a resonant circuit has been introduced. Using the novel circuit technology, soft-switching can be successfully realized for all the switches. Furthermore, in order to achieve accurate measurement of on-state resistance under switching operations, an active clamp circuit is employed. Operation principle and design analysis of the circuit are discussed. The dynamic measurement method is illustrated in detail. Simulation and experiments were carried out to verify the feasibility of the circuit. A special test circuit has been developed and built. Experimental results confirm that the proposed circuit gives a good insight of the devices performance in real applications.

Improved Bridgeless Interleaved Boost PFC Rectifier with Optimized Magnetic Utilization and Reduced Sensing Noise

Cao, Guoen,Kim, Hee-Jun The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

An improved bridgeless interleaved boost power factor correction (PFC) rectifier to improve power efficiency and component utilization is proposed in this study. With combined conventional bridgeless PFC circuit and interleaved technology, the proposed rectifier consists of two interleaved and magnetic inter-coupling boost bridgeless converter cells. Each cell operates alternatively in the critical conduction mode, which can achieve the soft-switching characteristics of the switches and increase power capacity. Auxiliary blocking diodes are employed to eliminate undesired circulating loops and reduce current-sensing noise, which are among the serious drawbacks of a dual-boost PFC rectifier. Magnetic component utilization is improved by symmetrically coupling two inductors on a unique core, which can achieve independence from each other based on the auxiliary diodes. Through the interleaved approach, each switch can operate in the whole line cycle. A simple control scheme is employed in the circuit by using a conventional interleaved controller. The operation principle and theoretical analysis of the converter are presented. A 600 W experimental prototype is built to verify the theoretical analysis and feasibility of the proposed rectifier. System efficiency reaches 97.3% with low total harmonic distortion at full load.

A Novel Circuit for Characteristics Measurement of SiC Transistors

Cao, Guoen,Kim, Hee-Jun The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.4

This paper proposes a novel test circuit for SiC transistors. On-state resistance under practical application conditions is an important characteristic for the device reliability and conduction efficiency of SiC transistors. In order to measure the on-state resistance in practical applications, high voltage is needed, and high current is also necessary to ignite performance for the devices. A soft-switching circuit based on synchronous buck topology is developed in this paper. To provide high-voltage and high-current stresses for the devices without additional spikes and oscillations, a resonant circuit has been introduced. Using the novel circuit technology, soft-switching can be successfully realized for all the switches. Furthermore, in order to achieve accurate measurement of on-state resistance under switching operations, an active clamp circuit is employed. Operation principle and design analysis of the circuit are discussed. The dynamic measurement method is illustrated in detail. Simulation and experiments were carried out to verify the feasibility of the circuit. A special test circuit has been developed and built. Experimental results confirm that the proposed circuit gives a good insight of the devices performance in real applications.

A Wireless Power Transfer System Based on Inductive Coupling

Guoen Cao,Hee-Jun Kim,Jeawoo Lim 대한전기학회 2014 대한전기학회 학술대회 논문집 Vol.2014 No.4

This paper proposed a high-power and high-efficiency wireless power transfer system based on inductive coupling. The system consists of a transmitter resonant inverter, a electromagnetic induction link, and a receiver rectifier. The transmitter is based on a full-bridge phase shift inverter, while the inductive link is composed of two LC resonators as loosely coupled inductors. To improved the performance of the system, modeling method of the magnetically coupled link is proposed and analyzed. A 20W prototype circuit is developed and the performance of the proposed system has been studied for experimental verification. The results show that the system efficiency is up to 65% at full load.

Improved Bridgeless Interleaved Boost PFC Rectifier with Optimized Magnetic Utilization and Reduced Sensing Noise

Guoen Cao,Hee-Jun Kim 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

An improved bridgeless interleaved boost power factor correction (PFC) rectifier to improve power efficiency and component utilization is proposed in this study. With combined conventional bridgeless PFC circuit and interleaved technology, the proposed rectifier consists of two interleaved and magnetic inter-coupling boost bridgeless converter cells. Each cell operates alternatively in the critical conduction mode, which can achieve the soft-switching characteristics of the switches and increase power capacity. Auxiliary blocking diodes are employed to eliminate undesired circulating loops and reduce current-sensing noise, which are among the serious drawbacks of a dual-boost PFC rectifier. Magnetic component utilization is improved by symmetrically coupling two inductors on a unique core, which can achieve independence from each other based on the auxiliary diodes. Through the interleaved approach, each switch can operate in the whole line cycle. A simple control scheme is employed in the circuit by using a conventional interleaved controller. The operation principle and theoretical analysis of the converter are presented. A 600 W experimental prototype is built to verify the theoretical analysis and feasibility of the proposed rectifier. System efficiency reaches 97.3% with low total harmonic distortion at full load.

A High Performance Interleaved Bridgeless PFC for Nano-grid Systems

Cao, Guoen,Lim, Jea-Woo,Kim, Hee-Jun,Wang, Huan,Wang, Yibo The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.3

A high performance interleaved bridgeless boost power factor correction (PFC) rectifier operating under the critical current conduction mode (CrM) is proposed in this paper to improve the efficiency and system performance of various applications, such as nano-grid systems. By combining the interleaved technique with the bridgeless topology, the circuit contains two independent branches without rectifier diodes. The branches operate in interleaved mode for each respective half-line period. Moreover, when operating in CrM, all the power switches take on soft-switching, thereby reducing switching losses and raising system efficiency. In addition, the input current flows through a minimum amount of power devices. By employing a commercial PFC controller, an effective control scheme is used for the proposed circuit. The operating principle of the proposed circuit is presented, and the design considerations are also demonstrated. Simulations and experiments have been carried out to evaluate theoretical analysis and feasibility of the proposed circuit.

A High Performance Interleaved Bridgeless PFC for Nano-grid Systems

Guoen Cao,Jea-Woo Lim,Hee-Jun Kim,Huan Wang,Yibo Wang 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.3

A high performance interleaved bridgeless boost power factor correction (PFC) rectifier operating under the critical current conduction mode (CrM) is proposed in this paper to improve the efficiency and system performance of various applications, such as nano-grid systems. By combining the interleaved technique with the bridgeless topology, the circuit contains two independent branches without rectifier diodes. The branches operate in interleaved mode for each respective half-line period. Moreover, when operating in CrM, all the power switches take on soft-switching, thereby reducing switching losses and raising system efficiency. In addition, the input current flows through a minimum amount of power devices. By employing a commercial PFC controller, an effective control scheme is used for the proposed circuit. The operating principle of the proposed circuit is presented, and the design considerations are also demonstrated. Simulations and experiments have been carried out to evaluate theoretical analysis and feasibility of the proposed circuit.

Novel flexible HVDC transmission converter station topology with DC fault blocking capability

Huo, Qunhai,Wang, Peng,Cao, Guoen,Zhu, Jin,Yin, Jingyuan,Guo, Xinming,Wei, Tongzhen The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.4

The conventional half-bridge submodule (HBSM)-based multilevel modular converter (MMC) cannot block DC faults. To solve this problem, a novel flexible overhead-line high-voltage direct current (HVDC) transmission converter station topology is proposed in this study, which provides DC fault blocking capability. By adding blocking submodules (SMs) onto the positive and negative DC buses of a conventional HBSM converter station, a rapid fault current blocking can be achieved in the case of a DC bus short circuit. The DC fault blocking principle of the proposed topology and the rapid fault blocking capability of the blocking SM are analyzed. The quantity of required major components is also calculated. In addition, the IGBT, the system loss and the control complexity quantities are comprehensively compared with those of existing topologies. The validity of the proposed topology is demonstrated based on simulation and experimental studies.

Molecular Cloning of Hemoglobin Alpha-chain Gene from Pantholops hodgsonii, a Hypoxic Tolerance Species

Yingzhong, Yang,Droma, Yunden,Guoen, Jin,Zhenzhong, Bai,Lan, Ma,Haixia, Yun,Yue, Cao,Kubo, Keishi,Rili, Ge Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.3

To investigate the possible mechanisms of high-altitude native animals in adapting to high altitude, we cloned hemoglobin alpha-chain (alpha-chain Hb) gene from Pantholops hodgsonii, an animal species that indigenously lives at elevations of 3700-5500 m on the Qinghai-Tibetan plateau. Using reverse transcription polymerase chain reaction (RT-PCR) technique, the alpha-chain Hb gene was amplified from total RNA in the liver of the Pantholops hodgsonii. TA cloning technique was used and the PCR product was cloned into pGEM-T vector. The DNA sequence of the gene was highly homologous with sheep (99.1%), goat (98.6%), cattle (95.6%) and human (86.5%). The alpha-chain Hb gene encoded a 142-amino acid protein that could be identified with the homology of alpha-chain Hb protein in sheep (98%), goat (96%), cattle (91%) and human (87%). However, 18 alternations were detected when compared with the alpha-chain Hb gene in human, and 2 in sheep. Moreover, the alterations of a117 GluAsp and $\alpha$132 AsnSer in important regions were noted in human and sheep, respectively. Phylogenetic analysis suggested that the structure of alpha-chain Hb was highly similar to that in sheep. This study provided essential information for elucidating the possible roles of hemoglobin in adapting to extremely high altitude in Pantholops hodgsonii.

A High Step-up Modular Isolated DC-DC Converter for Large Capacity Photovoltaic Generation System integrated into MVDC Grids

Shilei Lu,Kai Sun,Guoen Cao,Yongdong Li,Jung-Ik Ha,Geon-Hong Min 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Nowadays, the research and design of the DCDC conversion system has become more and more popular in the application of photovoltaic generation into the medium voltage DC (MVDC) grids. A novel high power modular isolated DC-DC converter with high step-up ratio is proposed as a module of the DC-DC conversion system in this paper. Based on the input parallel and output series (IPOS) connections of the proposed modular converters, the system is easy to achieve high capacity and high voltage. A two-stage structure is employed in the proposed converter. The interleaved boost topology is applied to the front-stage, which realizes MPPT for PV arrays with low input current ripples. The full-bridge LLC topology is employed as the back-stage, which lowers power losses by the implementation of softswitching. The voltage gain of the proposed converter is derived in detail. The theoretical analysis and control strategy are studied in depth. Simulation and experiment verify the feasibility and effectiveness of the proposed converter.