Gate driver for parallel connection SiC MOSFETs with over-current protection and dynamic current balancing scheme

Zhang, Yimeng,Song, Qingwen,Tang, Xiaoyan,Zhang, Yuming The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1

In this paper, a SiC MOSFETs gate driver for parallel connections is proposed and implemented. The proposed design enhances the reliability of parallel-connected SiC MOSFETs in high-frequency applications. High-speed over-current protections are applied for both over-voltage and under-voltage situations. In addition, a dynamic balancing current sharing scheme for SiC MOSFETs is proposed for high-speed parallel applications by current feedback and switching delay time compensation. With the proposed design, parallel-connected SiC MOSFETs can work at an operation frequency of 1 MHz with over-current protections. In addition, with the dynamic current balancing scheme, the operation temperature decreases from 115 to 86.9 ℃, while the temperature difference for paralleled devices drops from 25.8 to 1.8 ℃.

Finite-time Containment Control of Nonlinear Delayed Fractional Multi-agent Systems

Zeyi Wang,Song Liu,Xiaoyan Li 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.10

This article deals with finite-time containment control (FTCC) of nonlinear delayed fractional multiagent systems (FMASs). Addressing fractional Razumikhin approach, properties of fractional calculus and analytical techniques, a quadratic Lyapunov function is constructed to derive sufficient conditions on FTCC by adopting a discontinuous control protocol, the employed method may overcome well the troubles arising from time delays and fractional derivatives. Numerical simulations further clarify the reliability and validity of our theoretical conclusions.

An exchange bias observed in Tb/Cr/FeCo trilayers with ultrathin Cr layer at low temperature

Sun Li,Li Xiaoyan,Zhang Yiwei,Song Hengbo,Zhang Wen,Kou Zhaoxia,Zhang Dong,Liu Xiaoying,Fei Hongyang,Pan Mengmei,Zhao Zhibin,Zhai Ya 한국물리학회 2022 Current Applied Physics Vol.44 No.-

Positive exchange bias field (He) is observed in Tb/Cr (tCr)/FeCo trilayers at 5 K without cooling field, and negative He for Tb/FeCo bilayer. The negative He of Tb/FeCo implies the FM coupling at the interface due to Co and Fe dominate in the magnetization of the ferrimagnetic interlayer alloy of FeCo and Tb. With the inserting of Cr layer, this situation is broken, and the positive He implies the antiferromagnetic interlayer coupling. A peak of He = 6.0 mT for trilayers with tCr = 1.5 nm is corresponding to the minimum value of coercivity as a function of tCr at 5 K, which is used to study the effect of the cooling field (Hfc) on He as a function of temperature. It is found that Hfc of 100 mT triggers He from positive to negative at T ≤ 15 K. The magnetoresistance results also confirm the coexistence of multiple MR mechanisms in these trilayers.

Nematicidal activity against Aphelenchoides besseyi and Ditylenchus destructor of three biflavonoids, isolated from roots of Stellera chamaejasme

Hui Jin,Haiyan Cui,Xiaoyan Yang,Lihong Xu,Xudong Li,Rentao Liu,Zhiqiang Yan,Xiuzhuang Li,Weili Zheng,Yuhui Zhao,Xiaoxia Song,Lihua Zhong,Anxiang Su,Bo Qin 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.4

Aphelenchoides besseyi and Ditylenchus destructor can cause serious problems for a number of important agricultural crops and vegetables. In this study, the ethanol extract of Stellera chamaejasme L. roots showed strong nematicidal activity against Aphelenchoides besseyi and Ditylenchus destructor. By using a bioactivity-driven fractionation, three biflavonoids were isolated from the extract and their structures were identified by mass and nuclear magnetic resonance spectral data. Nematicidal activity bioassays revealed that isoneochamaejasmin A had the strongest nematicidal activity against A. besseyi and D. destructor with LC 50 values of 2.32 and 0.18 mM at 72 h, respectively. Chamaejasmenin B displayed weaker nematicidal activity against A. besseyi with an LC 50 value of 3.94 mM at 72 h. Neochamaejasmin B induced the lowest mortality against D. destructor with an LC 50 values of 15.6 mM at 72 h. These results suggested that the kind and position of substitutions and the relative configuration of 2-H/3-H and 2”-H/3”-H could be considered as important factors responsible for the nematicidal activity of these purified C-3/C-3″ biflavonoids.

Dynamic Performance and Stress Wave Propagation Characteristics of Parallel Jointed Rock Mass Using the SHPB Technique

Qirui Wang,Erxiang Song,Peng Xu,Yongsheng He,Xiaoyan Shi,Huanzhen Xie 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

To investigate the effects of joint number on dynamic compressive strength, crushing effect, stress wave propagation, stress wave conversion, and energy evolution of rock masses, SHPB and LS-DYNA were used to conduct impact experiments and numerical simulations, respectively. The results demonstrate that the dynamic strength of a multi-jointed (two- and three-jointed) rock are 11.1 and 25.1% lower, respectively, compared with that of a single-jointed rock. The weak surface near the joint causes the rock mass to crack first. The rock cracking time advances significantly as the joints number increases. The reflection coefficient falls as the number of joints increases, because the wave impedance of the joint differs from that of the rock. The transmission coefficient, however, is exactly the reverse. When the P wave strikes the specimen, the vibration direction of the particles is deflected at the joint, resulting in a shear wave. P waves are reflected and superimposed between joints, increasing the strength of shear waves and resulting in more transverse cracks in multi-jointed rock masses under dynamic loading. Meanwhile, the total energy consumed by a bedrock under dynamic loading is obviously larger than that of joints. However, the total energy absorbed by joints exceeds that of the bedrock when the joints number increases. The results further enrich the dynamic basis of jointed rock masses.

Protection Provided by a Gabexate Mesylate Thermo-Sensitive In Situ Gel for Rats with Grade III Pancreatic Trauma

Hanjing Gao,Qing Song,Faqin Lv,Shan Wang,Yiru Wang,Xiaoyan Li,Yukun Luo,Xingguo Mei,Jie Tang 거트앤리버 소화기연관학회협의회 2017 Gut and Liver Vol.11 No.1

Background/Aims: This study investigated the protection provided by gabexate mesylate thermo-sensitive in-situ gel (GMTI) against grade III pancreatic trauma in rats. Methods: A grade III pancreatic trauma model with main pancreatic duct dividing was established, and the pancreas anatomical diagram, ascites, and serum biochemical indices, including amylase, lipase, C-reactive protein (CRP), interleukin 6 (IL- 6), and tumor necrosis factor-α (TNF-α), were examined. The pancreas was sliced and stained with hematoxylin eosin and subjected to terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Results: Ascites, serum amylase, lipase, CRP, IL-6, and TNF-α levels were significantly increased in the pancreas trauma (PT) groups with prolonged trauma time and were significantly decreased after GMTI treatment. The morphological structure of the pancreas was loose, the acinus was significantly damaged, the nuclei were irregular and hyperchromatic, and there was inflammatory cell invasion in the PT group compared to the control. After GMTI treatment, the morphological structure of the pancreas was restored, and the damaged acinus and inflammatory cell invasion were decreased compared to the PT group. Moreover, the cell apoptosis index was significantly increased in the PT group and restored to the same levels as the control group after GMTI treatment. Conclusions: GMTI, a novel formulation and drug delivery method, exhibited specific effective protection against PT with acute pancreatitis therapy and has potential value as a minimally invasive adjuvant therapy for PT with acute pancreatitis.

Characterization and Expression Profile of CMTM3/CKLFSF3

Zhong, Ji,Wang, Yu,Qiu, Xiaoyan,Mo, Xiaoning,Liu, Yanan,Li, Ting,Song, Quansheng,Ma, Dalong,Han, Wenling Korean Society for Biochemistry and Molecular Biol 2006 Journal of biochemistry and molecular biology Vol.39 No.5

CMTM/CKLFSF is a novel family of proteins linking chemokines and TM4SF. In humans, these proteins are encoded by nine genes, CKLF and CMTM1-8/CKLFSF1-8. Here we report the characteristics and expression profile of CMTM3/CKLFSF3. Human CMTM3/CKLFSF3 has a high sequence identity among various species and similar characteristics as its mouse and rat homologues. Established by results both of RT-PCR and Quantitative Real-time PCR, the gene is highly transcribed in testis, leukocytes and spleen. For further verification, we generated a polyclonal antibody against human CMTM3/CKLFSF3 and found that the protein is highly expressed in the testis and some cells of PBMCs. Therefore, CMTM3/CKLFSF3 is an evolutionarily conserved gene that may have important roles in the male reproductive system and immune system. Further studies are necessary to validate its functions in the two systems.

Joint toxicity of methoxyfenozide and lufenuron on larvae of Spodoptera exigua Hübner (Lepidoptera: Noctuidae)

Jixiang Chen,Weili Jiang,Hongyan Hu,Xiaoyan Ma,Qian Li,Xianpeng Song,Xiangliang Ren,Yan Ma 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.3

The joint action and sublethal effects of methoxyfenozide and lufenuron were measured against Spodoptera exigua. Methoxyfenozide and lufenuron exhibited optimum synergistic toxicity on S. exigua at a mass ratio of 4:6, and the co-toxicity coefficient (CTC) was 165.705. Third instars larvae of S. exigua were treated with methoxyfenozide (LC 15 = 21.004 ng/cm 2 ), lufenuron (LC 15 = 27.134 ng/cm 2 ), or a mixture of methoxyfenozide and lufenuron (MML, LC 15 = 16.503 ng/cm 2 ) through feeding for 72 h. Ingestion of MML by larvae significantly inhibited larval and pupal weights and pupation rate, and prolonged the larval and pupal development of S. exigua compared to individual treatment ofmethoxyfenozide or lufenuron. Both methoxyfenozide and MML treatments significantly decreased the fertility of female S. exigua. No significant changes were observed in case of adult emergence and egg hatching for different treatments. The MML-treated S. exigua exhibited significantly lower activities of polyphenol oxidase (PPO) and cytochrome P450 (CYP450) than those in S. exigua treated separately with methoxyfenozide or lufenuron. Finally, methoxyfenozide, lufenuron, and MML treatments decreased chitinase, acetylcholinesterase (AChE), carboxylesterase (CarE), and glutathione-s-transferase (GST) activities in S. exigua.

The Signal Injection Method with High-Frequency for Distribution Network Capacitive Current Measurement

Sun Yanzhou,Han Wu,Liu Xiaoqian,Song Xiaoyan,Wei Yanfang 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.2

In order to solve the problem of limited frequency selection range and simplify calculations on the grounded capacitance measurement for the ungrounded distribution system, a high-frequency injecting method for the capacitive current measurement is proposed in the paper. The injecting frequency can be high enough to ignore capacitive reactance and leakage resistance comparing with leakage inductance. The leakage inductance value is obtained directly on the base of simplifi ed calculation. Then the resonant frequency of the power system needs to be obtained by the traditional resonant method. Finally, the grounded capacitance can be calculated through the equivalent circuit and the simultaneous equations. The simulation and experiments verify the feasibility of the high-frequency method. The experiment results prove that this method not only solves the problem of frequency selection, but also has advantages of convenience and high precision (the relative error is less than 5%), which is also suitable for the larger grounded capacitance system.

Novel modulation method for torque ripple suppression of brushless DC motors based on SIMO DC-DC converter

Sun, Shikai,Guo, Hui,Zhang, Yimeng,Jia, Yupeng,Lv, Hongliang,Song, Qingwen,Tang, Xiaoyan,Zhang, Yuming The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.3

In this paper, a novel modulation method is proposed for the torque ripple suppression of a brushless DC motor (BLDCM) during both the commutation period and the speed regulation period. The main sources of torque ripple are the imbalance current during commutation and the PWM during speed regulation. A single-inductor multiple-output (SIMO) Buck DC-DC converter is adopted to generate input voltage for the inverter driver of a BLDCM. During the commutation period, the input voltage of an inverter can be adjusted to four times the back electromotive force (EMF), which suppresses the torque ripple caused by imbalance commutation current. Meanwhile, by changing the output voltage of a SIMO DC-DC, the speed of a BLDCM can be regulated without PWM on the inverter switches, which also suppresses the torque ripple. A control algorithm is applied on a Field Programmable Gate Array (FPGA), and the proposed BLDCM drive prototype is fabricated and tested. Measurement results show that with the proposed speed regulation strategy, the torque ripple is suppressed from 33.3% to 20.1%, and that with the proposed suppression strategy in commutation, the torque ripple is suppressed further to 5.3%.