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Jieqin Li,Yihua Wang,Juntao Chai,Lihua Wang,Chunming Wang,Wuhua Long,Di Wang,Yunlong Wang,Ming Zheng,Cheng Peng,Mei Niu,Jianmin Wan 한국식물학회 2013 Journal of Plant Biology Vol.56 No.5
The nuclear genes involved in chloroplast developmentand chlorophyll biosynthesis must be investigated tounderstand their functions in plant growth and development. In this study, we isolated and identified a unique leaf-colormutant of rice with a green-yellow phenotype before thefour-leaf stage and named the mutation green-revertiblechlorina 1 (grc1). The mutants had significantly lower plantheight, number of tillers, and panicle length and headedsignificantly earlier than the wild type. The levels ofchlorophylls, carotenoids, and chlorophyll precursors werealso lower. The mutation in grc1 affected chloroplastultrastructure, particularly thylakoid development. Geneticanalysis indicated that the green-yellow phenotype wascontrolled by a single recessive gene. We mapped the grc1gene to a 32.4-kb region on the long arm of chromosome 6. Through map-based cloning, we identified a 45-bp insertionin the genomic region of LOC_Os06g40080, which encodeda heme oxygenase. Expression of LOC_Os06g40080 wassignificantly down-regulated in the grc1 mutant. Subcellularlocalization showed that this heme oxygenase was localizedin the chloroplast. In summary, we isolated and identified thegene for grc1, which plays an important role in chlorophyllbiosynthesis and chloroplast development in rice.
Yuxiang Wang,Yunjie Gu,Wuhua Li,Xiangning He 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In virtual vector control schemes for singlephase current-regulated voltage source inverters, a transient disturbance may be induced due to the time-delay in the virtual orthogonal signal. This disturbance deteriorates the dynamic current-tracking capability and power quality. A unified scalar model is developed to analyze the phenomenon. Based on this model, an improved control scheme with a pre-compensator is proposed to solve the problem. The pre-compensator reshapes the current commands so that the transient disturbance signal is eliminated while the desired response is unaffected. Experimental results of the proposed strategy are compared with the conventional solution to substantiate enhanced dynamic performance.
Luo, Haoze,Dong, Yufei,Li, Wuhua,He, Xiangning The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
A modular multilevel-clamped composited multilevel converter ($M-MC^2$) is proposed. $M-MC^2$ enables topology reconfiguration, power device reuse, and composited clamping. An advanced five-level converter ($5L-M-MC^2$) is derived from the concept of $M-MC^2$. $5L-M-MC^2$ integrates dual three-level T-type modules and one three-level neutral point clamped module. This converter can also integrate dual three-level T-type modules and one passive diode module by utilizing the device reuse scheme. The operation principle and SPWM modulation are discussed to highlight converter performance. The proposed $M-MC^2$ is comprehensively compared with state-of-the-art five-level converters. Finally, simulations and experimental results are presented to validate the effectiveness of the main contributions of this study.
Haoze Luo,Yufei Dong,Wuhua Li,Xiangning He 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
A modular multilevel-clamped composited multilevel converter (M-MC²) is proposed. M-MC² enables topology reconfiguration, power device reuse, and composited clamping. An advanced five-level converter (5L-M-MC²) is derived from the concept of M-MC². 5L-M-MC² integrates dual three-level T-type modules and one three-level neutral point clamped module. This converter can also integrate dual three-level T-type modules and one passive diode module by utilizing the device reuse scheme. The operation principle and SPWM modulation are discussed to highlight converter performance. The proposed M-MC² is comprehensively compared with state-of-the-art five-level converters. Finally, simulations and experimental results are presented to validate the effectiveness of the main contributions of this study.
A Busbar Integrated SiC-based Converter with Embedded Heat-pipes
Yao Chang,Amir Sajjad Bahman,Haoze Luo,Wuhua Li,Xiangning He,Francesco Iannuzzo,Frede Blaabjerg 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
In this paper, a bus-bar integrated packaging technology for press-pack power modules is proposed. The proposed packaging technology features high power-density, even pressure distribution among chips, and low stray parameters. The structure design and fabrication flow process are analyzed and experiments are made to verify the feasibility of proposed solution. The critical challenge about the package is related to thermal management. To reduce the thermal stress of chips, a heat-pipe integrated heatsink is developed and finite-element-method (FEM) simulations are used to evaluate the cooling performance of the proposed heatsink. The results demonstrate that the proposed heatsink has a relatively low cost and works effectively. It paves the way to better packaging design and more efficient thermal management method for high power devices.
Synchronous Frequency Resonance of Virtual Synchronous Generators and Damping Control
Jinhua Wang,Yuxiang Wang,Yunjie Gu,Wuhua Li,Xiangning He 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
The Virtual Synchronous Generator (VSG) is an effective solution for high-penetration renewable energy sources integrated into the power system. Although the VSG has a similar behavior as the conventional synchronous generator, the fast and flexible control capability of converters may give rise to some specific characteristics. In this paper, it is explained that flux dynamics may induce synchronous frequency resonance in VSGs, which possibly leads to power-angle oscillations. A precise small-signal model is established to investigate the synchronous frequency resonance phenomenon. Based on this model, two damping control methods are proposed, which suppress the resonance through increasing the virtual mechanical inertia or adding virtual electrical resistance. The effectiveness of the theoretical conclusions is verified by simulation and experimental results.
Yuting Jin,Shuoyu Ye,Qiang Wu,Haoze Luo,Wuhua Li,Xiangning He 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-
The electroluminescence effect of SiC MOSFET is correlated with parameters such as junction temperature and device current, providing a new approach for nonintrusive online device status sensing. However, existing discrete photodiode solutions have encountered bottlenecks with increasing monitoring parameters and decreasing sampling delays. This work proposes a SiC device status monitoring scheme based on the integrated miniature hyperspectral spectrometer. Convolutional smoothing and partial least squares regression are applied to the obtained hyperspectral data sets. The real-time online monitoring of junction temperature and device current is achieved under low signal-to-noise ratios where the device only emits light in the dead time. The synchronous detection errors for temperature and current are only 3.11°C and 0.81A, respectively.
State-Space Modeling of DC Distribution Systems: Experimental Validation
Nils H. van der Blij,Laura M. Ramirez-Elizondo,Matthijs T.J. Spaan,Wuhua Li,Pavol Bauer 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
To tackle the challenges of future distribution systems, dc is being reconsidered. However, broad adoption of dc distribution systems requires additional research into the modeling, stability, protection and control of these systems. Previous research presents modeling methods that only consider monopolar configurations and do not take mutual couplings into account. Therefore, this paper presents a state-space method that can be applied to any dc distribution system, regardless of configuration and mutual couplings. Moreover, it shows how the state-space matrices can be derived in a programmatic manner. Furthermore, the models are validated using an experimental dc microgrid set-up. Due to the mathematical nature, the presented modeling method can be applied easily, and the stability and control can be analyzed algebraically.