Study on a Novel Switching Pattern Current Control Scheme Applied to Three-Phase Voltage-Source Converters

Hongyan Zhao,Yan Li,Trillion Q. Zheng 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

This paper presents a novel switching pattern current control (SP-CC) scheme, which is applied in three-phase voltage-source converters (VSCs). This scheme can select the optimal output switching pattern (SP) by referring the basic principle of space vector modulation (SVM). Moreover, SP-CC is a method without a carrier wave. Thus, the implementation process is concise and easy. When compared with the conventional hysteresis current control (C-HCC) and the space vector-based hysteresis current control (SV-HCC), the SP-CC has the performances of faster dynamic response of C-HCC and less switching number (SN) of SV-HCC. In addition, it has less harmonic contents in the three-phase current, along with a lower switching loss and a higher efficiency. Moreover, the hysteresis bandwidth and Clarke conversion are not required in the SP-CC. The effectiveness of the presented SP-CC is verified by simulation and experimental test results. In addition, the advantages of the SP-CC, when compared with the C-HCC and SV-HCC, are verified as well.

Study on a Novel Switching Pattern Current Control Scheme Applied to Three-Phase Voltage-Source Converters

Zhao, Hongyan,Li, Yan,Zheng, Trillion Q. The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

This paper presents a novel switching pattern current control (SP-CC) scheme, which is applied in three-phase voltage-source converters (VSCs). This scheme can select the optimal output switching pattern (SP) by referring the basic principle of space vector modulation (SVM). Moreover, SP-CC is a method without a carrier wave. Thus, the implementation process is concise and easy. When compared with the conventional hysteresis current control (C-HCC) and the space vector-based hysteresis current control (SV-HCC), the SP-CC has the performances of faster dynamic response of C-HCC and less switching number (SN) of SV-HCC. In addition, it has less harmonic contents in the three-phase current, along with a lower switching loss and a higher efficiency. Moreover, the hysteresis bandwidth and Clarke conversion are not required in the SP-CC. The effectiveness of the presented SP-CC is verified by simulation and experimental test results. In addition, the advantages of the SP-CC, when compared with the C-HCC and SV-HCC, are verified as well.

Control and Analysis of Vienna Rectifier Used as the Generator-Side Converter of PMSG-based Wind Power Generation Systems

Zhao, Hongyan,Zheng, Trillion Q.,Li, Yan,Du, Jifei,Shi, Pu The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1

Permanent-Magnet Synchronous Generators (PMSGs) are used widely in Wind Power Generation Systems (WPGSs), and the Vienna rectifier was recently proposed to be used as the generator-side converter to rectify the AC output voltage in PMSG-based WPGS. Compared to conventional six-switch two-level PWM (2L-PWM) converters, the Vienna rectifier has several advantages, such as higher efficiency, improved total harmonic distortion, etc. The motivation behind this paper is to verify the performance of direct-driven PMSG wind turbine system based-Vienna rectifier by using a simulated direct-driven PMSG WPGS. In addition, for the purpose of reducing the reactive power loss of PMSGs, this paper proposes an induced voltage sensing scheme which can make the stator current maintain accurate synchronization with the induced voltage. Meanwhile, considering the Neutral-Point Voltage (NPV) variation in the DC-side of the Vienna rectifier, a NPV balancing control strategy is added to the control system. In addition, both the effectiveness of the proposed method and the performance of the direct-driven PMSG based-Vienna rectifier are verified by simulation and experimental results.

Control and Analysis of Vienna Rectifier Used as the Generator-Side Converter of PMSG-based Wind Power Generation Systems

Hongyan Zhao,Trillion Q. Zheng,Yan Li,Jifei Du,Pu Shi 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1

Permanent-Magnet Synchronous Generators (PMSGs) are used widely in Wind Power Generation Systems (WPGSs), and the Vienna rectifier was recently proposed to be used as the generator-side converter to rectify the AC output voltage in PMSG-based WPGS. Compared to conventional six-switch two-level PWM (2L-PWM) converters, the Vienna rectifier has several advantages, such as higher efficiency, improved total harmonic distortion, etc. The motivation behind this paper is to verify the performance of direct-driven PMSG wind turbine system based-Vienna rectifier by using a simulated direct-driven PMSG WPGS. In addition, for the purpose of reducing the reactive power loss of PMSGs, this paper proposes an induced voltage sensing scheme which can make the stator current maintain accurate synchronization with the induced voltage. Meanwhile, considering the Neutral-Point Voltage (NPV) variation in the DC-side of the Vienna rectifier, a NPV balancing control strategy is added to the control system. In addition, both the effectiveness of the proposed method and the performance of the direct-driven PMSG based-Vienna rectifier are verified by simulation and experimental results.

Degradation of Lignocelluloses in Rice Straw by BMC-9, a Composite Microbial System

( Hongyan Zhao ),( Hai Ru Yu ),( Xu Feng Yuan ),( Ren Zhe Piao ),( Hu Lin Li ),( Xiao Fen Wang ),( Zong Jun Cui ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.5

To evaluate the potential utility of pretreatment of raw biomass with a complex microbial system, we investigated the degradation of rice straw by BMC-9, a lignocellulose decomposition strain obtained from a biogas slurry compost environment. The degradation characteristics and corresponding changes in the bacterial community were assessed. The results showed that rapid degradation occurred from day 0 to day 9, with a peak total biomass bacterium concentration of 3.3 × 10(8) copies/ml on day 1. The pH of the fermentation broth declined initially and then increased, and the mass of rice straw decreased steadily. The highest concentrations of volatile fatty acid contents (0.291 mg/l lactic acid, 0.31 mg/l formic acid, 1.93 mg/l acetic acid, and 0.73 mg/l propionic acid) as well as the highest xylanse activity (1.79 U/ml) and carboxymethyl cellulase activity (0.37 U/ml) occurred on day 9. The greatest diversity among the microbial community also occurred on day 9, with the presence of bacteria belonging to Clostridium sp., Bacillus sp., and Geobacillus sp. Together, our results indicate that BMC-9 has a strong ability to rapidly degrade the lignocelluloses of rice straw under relatively inexpensive conditions, and the optimum fermentation time is 9 days.

Novel Load Disturbance Observer-based Global Complementary Sliding Mode Control for a Precision Motion Stage Driven by PMLSM

Hongyan Jin,Ximei Zhao,TianheWang 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.11

In this paper, a novel load disturbance observer-based global complementary sliding mode control (NLDOB-GCSMC) method is proposed to achieve high servo performance of the precision motion stage driven by a permanent magnet linear synchronous motor (PMLSM). The global complementary sliding mode control (GCSMC) method incorporates an approach angle into the saturation function to realize the dynamic change of the boundary layer, which guarantees the asymptotic stability and improves the global robustness of the system. Besides, compared to hybrid CSMC strategies, the GCSMC method has a simpler structure and faster response speed. However, in practical applications, the load disturbance has a significant impact on system performance. Therefore, a novel load disturbance observer (NLDOB) capable of identifying the load variation is proposed. According to the model reference adaptive identification (MRAI) theory, NLDOB can identify the load disturbance on-line and realize compensation to further improve the robustness. The more accurate tracking performance and stronger robustness of the proposed control scheme compared to conventional approaches have been confirmed through comparative experimental studies.

<i>Spatholobus suberectus</i> Exhibits Antidiabetic Activity In Vitro and In Vivo through Activation of AKT-AMPK Pathway

Zhao, Peijun,Alam, Md Badrul,Lee, Seok-hyun,Kim, Young-Jun,Lee, Seul,An, Hongyan,Choi, Hee-Jeong,Son, Hyeong-U,Park, Chul-Hong,Kim, Hyo-Hyun,Lee, Sang-Han Hindawi 2017 Evidence-based Complementary and Alternative Medic Vol.2017 No.-

<P>Glucose deposition in peripheral tissue is an important parameter for the treatment of type 2 diabetes mellitus. The aim of this study was to investigate the effects of<I> Spatholobus suberectus</I> (Ss) on glucose disposal in skeletal muscle cells and additionally explore its in vivo antidiabetic potential. Treatment of ethanolic extract of<I> S. suberectus</I> (EeSs) significantly enhanced the glucose uptake, mediated through the enhanced expression of GLUT4 in skeletal muscle via the stimulation of AKT and AMPK pathways in C2C12 cells. Moreover, EeSs have potential inhibitory action on <I>α</I>-glucosidase activity and significantly lowered the postprandial blood glucose levels in STZ-induced diabetic mice, associated with increased expression of GLUT4 and AKT and/or AMPK-mediated signaling cascade in skeletal muscle. Furthermore, administration of EeSs significantly boosted up the antioxidant enzyme expression and also mitigated the gluconeogenesis enzyme such as PEPCK and G-6-Pase enzyme expression in liver tissue of STZ-induced diabetic mice model. Collectively, these findings suggest that EeSs have a high potentiality to mitigate diabetic symptoms through stimulating glucose uptake in peripheral tissue via the activation of AKT and AMPK signaling cascade and augmenting antioxidant potentiality as well as blocking the gluconeogenesis process in diabetic mice.</P>

Automatic bearing diagnosis based on improved empirical wavelet decomposition and nonparametric test

Hongyan Jiang,Keqin Zhao,Lifei Chen,Dianjun Fang,Feng Cheng,Yong Chen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

The 1/3-binary tree structure bandwidth is fixed, while the bands containing fault information sometimes do not fall equally in the fixed structure. To solve this problem, it is proposed to utilize the power spectrum to replace the Fourier spectrum, and to reconstruct the signal based on the scale space representation for the empirical wavelet decomposition. The fluctuation characteristics of the power spectrum frequency components and the energy distribution within frequency bands are taken full advantage of in this method. A new size parameter updating mechanism is employed to accelerate the signal reconstruction process. At the same time, it is thought that fault frequency is affected by the factor of slippage phenomena in order to realize a self-running diagnosis of bearing failure, and the occurring probability of the bearing fault is introduced to transform the envelope spectrum into a scalar indicator. As a result, without human intervention, the whole failure diagnosis process of the rolling bearing can be achieved by the manner of nonparametric testing. Simulation signal analysis results and experimental analysis results demonstrate the effectiveness and superiority of the proposed method.

Antimelanogenic Effect of an <i>Oroxylum indicum</i> Seed Extract by Suppression of MITF Expression through Activation of MAPK Signaling Protein

Zhao, Peijun,Alam, Md Badrul,An, Hongyan,Choi, Hee-Jeong,Cha, Yeong Ho,Yoo, Chi-Yeol,Kim, Hyo-Hyun,Lee, Sang-Han MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.3

<P>In this study, the antimelanogenic effect of an ethyl acetate fraction of <I>Oroxylum indicum</I> Vent. seeds (OISEA) and its underlying mechanisms in melan-a cells were investigated. Antimelanogenesis activity was confirmed by assessing inhibition of tyrosinase activity and melanin content in the cells. Both transcriptional and translational expression of microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase related protein-1 and 2 (TYRP-1 and TYRP-2), were also examined. The results depicted that pretreatment of OISEA significantly inhibits not only tyrosinase activity, but melanin production and intracellular tyrosinase activity. By repressing the expression of tyrosinase, TYRP-1, TYRP-2, and MITF, OISEA interrupted melanin production. Additionally, OISEA interfered with the phosphorylation of p38, extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun N-terminal kinase (JNK), with the reversal of OISEA-induced melanogenesis inhibition after treatment with the specific inhibitors SB239063, U0126, and SP600125. Overall, these results suggest that OISEA can stimulate p38, ERK1/2, JNK phosphorylation, and subsequent suppression of melanin, leading to the inhibition of melanogenic enzymes and melanin production, possibly owing to the presence of polyphenolic compounds.</P>

Predicting Cultural Values in Islamic Countries: The Six Cultural Dimensions of Hofstede’s Model

이지석,ZHAO HONGYAN,허지현,최룡,권종욱 연세대학교 경영연구소 2020 연세경영연구 Vol.57 No.1

The aim of this paper is to estimate and analyse the cultural value scores of the 57 Islamic countries that were not included in Hofstede’s model. Hofstede conducted one of the most comprehensive studies about how values in the workplace are influenced by culture. His data covered more than 100 countries, and the study included the largest group of respondents of any cross-cultural value survey at the time. Given its popularity and the large number of countries encompassed, Hofstede’s model includes surprisingly few Islamic countries. To the best of our knowledge, the present study is the first to analyse the cultural value scores of the 57 Islamic countries. The results reveal that the Islamic countries are all densely clustered in the collectivist and large power distance dimensions. Regarding the uncertainty avoidance and masculinity dimensions, the Islamic countries mostly have medium scores and are intensively clustered. Islamic countries are mostly clustered in the restrained and short-term orientation dimensions. The finding that the cultural distance among Islamic countries is much greater than that between Islamic countries and non-Islamic countries is interesting. We also summarized some implications of the characteristics of the cultural values of Islamic countries. Multinational corporations must seriously consider adjusting their management practice approaches to align with Islamic culture to maximize performance.