A Novel Phase Locked Loop for Grid-Connected Converters under Non-Ideal Grid Conditions

Long-Yue Yang,Chong-Lin Wang,Jian-Hua Liu,Chen-Xi Jia 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

Grid synchronization is one of the key techniques for the grid-connected power converters used in distributed power generation systems. In order to achieve fast and accurate grid synchronization, a new phase locked loop (PLL) is proposed on the basis of the complex filter matrixes (CFM) orthogonal signal generator (OSG) crossing-decoupling method. By combining first-order complex filters with relation matrixes of positive and negative sequence voltage components, the OSG is designed to extract specific frequency orthogonal signals. Then, the OSG mathematical model is built in the frequency-domain and time-domain to analyze the spectral characteristics. Moreover, a crossing-decoupling method is suggested to decouple the fundamental voltage. From the eigenvalue analysis point of view, the stability and dynamic performance of the new PLL method is evaluated. Meanwhile, the digital implementation method is also provided. Finally, the effectiveness of the proposed method is verified by experiments under unbalanced and distorted grid voltage conditions.

Sliding Mode Control of Three-Phase Four-Leg Inverters via State Feedback

Yang, Long-Yue,Liu, Jian-Hua,Wang, Chong-Lin,Du, Gui-Fu The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

To optimize controller design and improve static and dynamic performances of three-phase four-leg inverter systems, a compound control method that combines state feedback and quasi-sliding mode variable structure control is proposed. The linear coordinate change matrix and the state variable feedback equations are derived based on the mathematical model of three-phase four-leg inverters. Based on system relative degrees, sliding surfaces and quasi-sliding mode controllers are designed for converted linear systems. This control method exhibits the advantages of both state feedback and sliding mode control. The proposed controllers provide flexible dynamic control response and excellent stable control performance with chattering suppression. The feasibility of the proposed strategy is verified by conducting simulations and experiments.

A Novel Phase Locked Loop for Grid-Connected Converters under Non-Ideal Grid Conditions

Yang, Long-Yue,Wang, Chong-Lin,Liu, Jian-Hua,Jia, Chen-Xi The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

Grid synchronization is one of the key techniques for the grid-connected power converters used in distributed power generation systems. In order to achieve fast and accurate grid synchronization, a new phase locked loop (PLL) is proposed on the basis of the complex filter matrixes (CFM) orthogonal signal generator (OSG) crossing-decoupling method. By combining first-order complex filters with relation matrixes of positive and negative sequence voltage components, the OSG is designed to extract specific frequency orthogonal signals. Then, the OSG mathematical model is built in the frequency-domain and time-domain to analyze the spectral characteristics. Moreover, a crossing-decoupling method is suggested to decouple the fundamental voltage. From the eigenvalue analysis point of view, the stability and dynamic performance of the new PLL method is evaluated. Meanwhile, the digital implementation method is also provided. Finally, the effectiveness of the proposed method is verified by experiments under unbalanced and distorted grid voltage conditions.

Sliding Mode Control of Three-Phase Four-Leg Inverters via State Feedback

Long-Yue Yang,Jian-Hua Liu,Chong-Lin Wang,Gui-Fu Du 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

To optimize controller design and improve static and dynamic performances of three-phase four-leg inverter systems, a compound control method that combines state feedback and quasi-sliding mode variable structure control is proposed. The linear coordinate change matrix and the state variable feedback equations are derived based on the mathematical model of three-phase four-leg inverters. Based on system relative degrees, sliding surfaces and quasi-sliding mode controllers are designed for converted linear systems. This control method exhibits the advantages of both state feedback and sliding mode control. The proposed controllers provide flexible dynamic control response and excellent stable control performance with chattering suppression. The feasibility of the proposed strategy is verified by conducting simulations and experiments.

An improved resonantly driven piezoelectric gas pump

Yue Wu,Yong Liu,Jian-Fang Liu,Long Wang,Xiaoyang Jiao,Zhigang Yang 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.3

Piezoelectric pumps have the potential to be used in a variety of applications, such as in air circulation and compression. However, piezoelectric membrane pumps do not have enough driving capacity, and the heat induced during the direct contact between the driving part and the gas medium cannot be dissipated smoothly. When the gas is blocked, the piezoelectric vibrator generates heat quickly, which may eventually lead to damage. Resonantly driven piezoelectric stack pumps have high performance but no price advantage. In this situation, a novel, resonantly driven piezoelectric gas pump with annular bimorph as the driver is presented. In the study, the working principle of the novel pump was analyzed, the vibration mechanics model was deter-mined, and the displacement amplified theory was studied. The outcome indicates that the displacement amplification factor is related with the original displacement provided by the piezoelectric bimorph. In addition, the displacement amplification effect is related to the stiffness of the spring lamination, adjustment spring, and piezoelectric vibrator, as well as to the systematic damping factor and the driving frequency. The experimental prototypes of the proposed pump were designed, and the displacement amplification effect and gas output performance were measured. At 70 V of sinusoidal AC driving voltage, the improved pump amplified the piezoelectric vibrator displacement by 4.2 times, the maximum gas output flow rate reached 1685 ml/min, and the temperature of the bimorph remained normal after 2000 hours of operation when the gas medium was blocked.

사판 수입 생쪽 분말 염료의 면직물에 대한 염색성 및 염색견뢰도 연구

양월 ( Yue Yang ),안춘순 ( Cheun Soon Ahn ),박진성 ( Jin Sung Park ),이룡춘 ( Long Chun Li ) 복식문화학회 2012 服飾文化硏究 Vol.20 No.4

The purpose of this research was to find the suitable dyeing method for dyeing cotton fabric into indigo blue color using the raw indigo powder dyes sold in the Korean market. The research focused primarily on the comparison of the non-reduced dyeing method and the reduced dyeing method. The dyeing effects using different dyeing temperatures (2 -80t) and different concentrations of reducing agent and alkali were also investigated. It was found that the reduced dyeing method must he used for dyeing cotton into indigo blue color using the commercial raw indigo powder dyes. The best result was obtained by 20t dyeing with the 40t dyeing giving a comparable result. The intensity of the blue color could be enhanced by increasing the alkali concentration. The non-reduced dyeing could not dye cotton fabric into indigo blue color at any given dyeing temperatures (2-8Ot). The reduce-dyed cotton fabrics showed a gradual color change upon repeated washing and extended sunlight exposure, the most color change occurring after the first two washing cycles and the first S hours of sunlight exposure, The standard tests of colorfastness showed that the reduce-dyed cotton fabrics had good to excellent colorfastness whereas the colorfastness of the non-reduce-dyed cotton fabrics were mostly poor.

RBM24 exacerbates bladder cancer progression by forming a Runx1t1/TCF4/miR-625-5p feedback loop

Yin Yue-Wei,Liu Kai-Long,Lu Bao-Sai,Li Wei,Niu Ya-Lin,Zhao Chen-Ming,Yang Zhan,Guo Ping-Ying,Qi Jin-Chun 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-

RNA–binding motif protein 24 (RBM24) acts as a multifunctional determinant of cell fate, proliferation, apoptosis, and differentiation during development by regulating premRNA splicing and mRNA stability. It is also implicated in carcinogenesis, but the functions of RBM24 in bladder cancer (BC) remain unclear. In the present study, we revealed that RBM24 was upregulated in BC tissues. Importantly, we found that a higher level of RBM24 was correlated with poor prognosis in BC patients. Overexpression of RBM24 promoted BC cell proliferation, while depletion of RBM24 inhibited BC cell proliferation in vivo and in vitro. Mechanistically, RBM24 positively regulated Runx1t1 expression in BC cells by binding to and enhancing Runx1t1 mRNA stability. Furthermore, Runx1t1 in turn promoted RBM24 expression by interacting with the transcription factor TCF4 and suppressing the transcription of miR-625-5p, which directly targets RBM24 and suppresses RBM24 expression. RBM24-regulated BC cell proliferation was moderated via the Runx1t1/TCF4/miR-625-5p feedback loop. These results indicate that the RBM24/Runx1t1/TCF4/miR-625-5p positive feedback loop participates in BC progression. Disruption of this pathway may be a potential therapeutic strategy for BC treatment.

In-pile tritium release behavior and the post-irradiation experiments of Li4SiO4 fabricated by melting process

Zhao Linjie,Yang Mao,Xiao Chengjian,Gong Yu,Ran Guangming,Chen Xiaojun,Li Jiamao,Yue Lei,Chen Chao,Hou Jingwei,Wang Heyi,Long Xinggui,Peng Shuming 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1

Understanding the tritium release and retention behavior of candidate tritium breeder materials is crucial for breeder blanket design. Recently, a melt spraying process was developed to prepare Li4SiO4 pebbles, which were subsequently subjected to the in-pile tritium production and extraction platform in China Mianyang Research Reactor (CMRR) to investigate their in-situ tritium release behavior and irradiation performance. The results demonstrate that HT is the main tritium release form, and adding hydrogen to the purge gas reduces tritium retention while increasing the HT percent in the purge gas. Post-irradiation experiments reveal that the irradiated pebbles darken in color and their grains swell, but the mechanical properties remain largely unchanged. It is concluded that the tritium residence time of Li4SiO4 made by melt spraying method at 467 ◦C is approximately 23.34 h. High-density Li4SiO4 pebbles exhibit tritium release at relatively low temperatures (<600 ◦C) that is mainly controlled by bulk diffusion. The diffusion coefficient at 525 ◦C and 550 ◦C is 1.19 × 10 11 cm2/s and 5.34 × 10 11 cm2/s, respectively, with corresponding tritium residence times of 21.3 hours and 4.7 hours.

Short-term, Multi-center Prospective Clinical Study of Short Implants Measuring Less Than 7mm

Kim, Young-Kyun,Yi, Yang-Jin,Kim, Su-Gwan,Cho, Yong-Seok,Yang, Choon-Mo,Liang, Po-Chin,Chen, Yu-Yal,I, Lee-Long,Sim, Christopher,Tan, Winston,Ser, Go Wee,Yue, Deng,Yi, Man,Ping, Gong Korean Academy of Dental Science 2010 Journal of korean dental science Vol.3 No.1

Objective : This prospective study sought to verify the stability of three types of short implants measuring 7mm or less. Materials and methods : Implants measuring 7mm or less were placed in patients at multicenter dental clinics in Korea, China, Taiwan, and Singapore. Initial stability, intraoperative and postoperative complications, crestal bone loss, and survival rate of the implant were prospectively evaluated. Results : The primary stability of a 6-mm implant was lower than that of a 7-mm implant. The marginal bone loss of short implants measuring less than 7mm was minimal. Complications such as wound dehiscence, implant mobility, and peri-implant mucositis developed, and these were associated with initial implant failure. The short-term survival rate of 6-mm implant was 93.7%, and that of 7-mm implant, 96.6%. Conclusion : Short implant for the mandible with insufficient height for the residual ridge can be selectively used. Poor primary stability and wound dehiscence can cause osseointegration failure and alveolar bone loss.

Short-term, Multi-center Prospective Clinical Study of Short Implants Measuring Less Than 7mm

Young-Kyun Kim,Yang-Jin Yi,Su-Gwan Kim,Yong-Seok Cho,Choon-Mo Yang,Po-Chin Liang,Yu-Yal Chen,Lee-Long I,Christopher Sim,Winston Tan,Go Wee Ser,Deng Yue,Man Yi,Gong Ping 대한치의학회 2010 Journal of korean dental science Vol.3 No.1