Implementation of the CC/CV Charge of the Wireless Power Transfer System for Electric Vehicle Battery Charge Applications

Van-Binh Vu(부 반 빈),Duc-Hung Tran(트란 덕 홍),Van-Long Pham(팜반롱),Woojin Choi(최우진) 전력전자학회 2015 전력전자학술대회 논문집 Vol.2015 No.11

Intelligent Charger with Online Battery Diagnosis Function

Van-Tuan Doan,Van-Binh Vu,Hai-Nam Vu,Duc-Hung Tran,Woojin Choi 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In the battery based applications, the performance of the system highly depends on the reliability of the battery. However, it is difficult to obtain the accurate information about the state-of-health (SOH) of battery during its operation. In this paper a 3kw battery charger with online battery diagnosis function which can estimate the SOH of the battery by using online impedance spectroscopy technique is introduced. For the charger, a phase shift full bridge converter with synchronous rectification has been adopted to implement constant current/constant voltage charge and diagnosis functions. The electrochemical impedance spectroscopy (EIS) is performed after the charge to obtain the information about the internal impedance of the battery module, hence the SOH can be estimated online by observing the impedance variation of the battery over time. All the design procedure of the proposed charger is detailed and the feasibility of the system is verified by the experimental results.

Inhibitory Effects of Vietnamese Medicinal Plants on Monoamine Oxidase Activity

Hung, Vu Manh,Minh, Chau Van,Kiem, Phan Van,Dang Thi Lan Huong,Nguyen Tien Dat,Kim, Young Ho 충남대학교 약학대학 의약품개발연구소 2002 藥學論文集 Vol.17 No.-

In vitro in screening test aiming to find monoamine oxidase (MAO) inhibitors from Vietnamese medicinal plants, the MeOH extracts of seventeen medicinal plants were tested for the inhibitory effects on monoamine oxidase activity. MAO was purified from mouse brain and its activity was determined by fluorospectrophotometer using kynuramine as a substrate. Five MeOH extracts of medicinal plants including Cnidium monnineri showed quite strong inhibitory effects at the concentration of 250 ㎍/㎖. Six MeOH extracts of herbs including Astragalus membranaceus showed moderate inhibitory effects on this enzyme. Seven medicinal plants which showed good inhibitory effects on MAO were fractionated with CH_2Cl_2, EtOAc, BuOH and H_2O, successively. They were investigated for the inhibitory effects on MAO.

Improved sliding mode observer for FOC control system with discontinuous PWM of sensorless PMSM

Vu Van Hung,윤경국,이성근 한국마린엔지니어링학회 2023 한국마린엔지니어링학회지 Vol.47 No.5

With the increasing number of electric cars worldwide, permanent-magnet synchronous motors (PMSMs) are becoming increasingly popular in the transportation industry. In parallel with the development of PMSM, many novel control strategies have been developed to make PMSM superior and robust. In all control strategies aimed at improving the operation of PMSMs, the control strategy using discontinuous pulse width modulation (DPWM) instead of continuous space vector pulse width modulation (CSVPWM) for field-oriented control (FOC) is widely used to reduce switching and save energy. However, this method has not been applied by researchers to sensorless PMSM control three-phase inverters. Therefore, this study investigated a sensorless PMSM control with a DPWM FOC and a traditional sliding-mode observer to estimate rotor positions. Additionally, a modified sliding-mode observer with a Park phase-locked loop (PLL) was designed experimentally to improve the stability of the PMSM speed and reduce harmonics in the output phase current for the inverter under the FOC with DPWM. The experimental results verified that the sliding-mode observer integrated with the Park PLL can improve the operation of the sensorless PMSMs under FOC with DPWM.

Effects of harmonic on battery lifetime based on variations of space vector modulation in inverter

Vu Van Hung,윤경국,이성근 한국마린엔지니어링학회 2023 한국마린엔지니어링학회지 Vol.47 No.5

Various regulations for the prevention of environmental pollution are being implemented worldwide. Environmental pollu-tion is mostly attributed to harmful gases emitted during engine combustion in ships or automobiles, including thermal power genera-tion. To solve this problem, electricity is produced and stored from new renewable energy sources, such as solar, wind, and wave power, and is used to propel ships and cars. Electric propulsion ships or electric vehicle systems consist of a battery, an inverter, and an electric motor. The DC power stored in the battery is composed of a sinusoidal AC voltage through an inverter and is applied to the electric motor. The most important aspect is to safely manage a battery, which is a core component of an electric propulsion system, to avoid explosion, overheating or the generation of an overcurrent. Therefore, it is important not only to always observe the ambient tempera-ture, rated voltage, and current but also to remove factors that may harm the safety of the battery in advance. In particular, the sinusoidal AC voltage applied to the motor modulates the command voltage into the form of a switching pulse, which is then applied to the upper and lower legs (Leg) of the inverter. Therefore, the voltage and current of the inverter contain various harmonics that can adversely affect the propulsion system, including the batteries. In this study, the modulation types of the two switching pulses are selected, and motor-speed control is performed according to each type. Simultaneously, the relationship between the harmonics and lifetime is ana-lyzed by measuring the current harmonics flowing through an electrical motor and the internal resistance, which is a parameter that can predict the lifetime of the battery.

High-performance nonenzymatic electrochemical glucose biosensor based on AgNP-decorated MoS2 microflowers

Dinh Van Tuan,Dang Thi Thuy Ngan,Dao Vu Phuong Thao,Nguyen Thi Nguyet,Nguyen Thi Thuy,Nguyen Phuong Thuy,Vu Van Thu,Vuong-Pham Hung,Phuong Dinh Tam 한국물리학회 2022 Current Applied Physics Vol.43 No.-

A facile hydrothermal route was used to synthesize silver nanoparticle (AgNP)-decorated microflower molybdenum disulfide (MoS2-MF) for bio-electrochemical platform fabrication to detect nonenzymatic glucose concentration. The morphologies of the materials were studied by scanning electron microscopy, and their structural characteristics were analyzed by X-ray diffractometry and energy-dispersive X-ray spectroscopy. The electrochemical characteristics of the AgNPs/MoS2-MF/PtE biosensor were studied by cyclic voltammetry. The obtained data indicated that the developed nonenzymatic glucose sensor has a large linear response between 1.0 and 15.0 mM, a limit of detection of as low as 1.0 mM, and a sensitivity of 46.5 μA nM-1 cm-2. The biosensor also displayed outstanding selectivity, stability, reproducibility, and repeatability. Additionally, the AgNPs/MoS2-MF/ PtE biosensor was utilized to detect glucose concentration in real sample and showed practical application potential for glucose detection.

Fully nonlinear inelastic analysis of rectangular CFST frames with semi-rigid connections

Van-Tuong Bui,Quang-Viet Vu,Viet-Hung Truong,Seung-Eock Kim 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.5

In this study, an effective numerical method is introduced for nonlinear inelastic analyses of rectangular concrete-filled steel tubular (CFST) frames for the first time. A steel-concrete composite fiber beam-column element model is developed that considers material, and geometric nonlinearities, and residual stresses. This is achieved by using stability functions combined with integration points along the element length to capture the spread of plasticity over the composite cross-section along the element length. Additionally, a multi-spring element with a zero-length is employed to model the nonlinear semi-rigid beam-to-column connections in CFST frame models. To solve the nonlinear equilibrium equations, the generalized displacement control algorithm is adopted. The accuracy of the proposed method is firstly verified by a large number of experiments of CFST members subjected to various loading conditions. Subsequently, the proposed method is applied to investigate the nonlinear inelastic behavior of rectangular CFST frames with fully rigid, semi-rigid, and hinged connections. The accuracy of the predicted results and the efficiency pertaining to the computation time of the proposed method are demonstrated in comparison with the ABAQUS software. The proposed numerical method may be efficiently utilized in practical designs for advanced analysis of the rectangular CFST structures.

Impacts of Ownership Structure on Systemic Risk of Listed Companies in Vietnam

VU, Van Thi Thuy,PHAN, Nghia Trong,DANG, Hung Ngoc Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.2

The research objective of the paper is to clarify the factors influencing system risks of listed companies in Vietnam, with a focus on clarifying the relationship and quantifying the impacts of ownership structure on systemic risk of listed companies. The data used in this study included financial statements and stock price data of listed companies on the Ho Chi Minh City Stock Exchange and Hanoi Stock Exchange of Vietnam stock market in the period from 2010 to 2017. The paper used the method of estimation in establising the regression models to choose among three models: Random Effect Model, Fixed Effect Model or Pooled OLS for regression using Stata statistical software. The research results showed that state ownership and ownership by foreign investors were positively related to systemic risk, while ownership by domestic investors had a reverse relationship with systemic risk of listed companies in Vietnam. In addition, as a control variable, both company size and profitability had an effect on the systemic risk of listed companies in the research sample. Based on the research results, the authors interpreted some of the implications in order to minimize systemic risks in the operation of listed companies in Vietnam.

Profitability and the Distance to Default: Evidence from Vietnam Securities Market

Van Thuy Thi VU,Nhung Hong DO,Hung Ngoc DANG,Tram Ngoc NGUYEN 한국유통과학회 2019 The Journal of Asian Finance, Economics and Busine Vol.6 No.4

The paper examines the influence of profitability on distance to default (DD) in Vietnam securities market. The investigated sampl e consists of 211 companies listed on HOSE during 18 years from 2010 to 2017. We apply KMV model to calculate distance to d efault and use both macroeconomics factors and firm specific factors as independent variables. Using General Least Squared (GL S) method, we find evidence to confirm the positive relationship between profitability and distance to default. This result showed t hat, although profitability did not directly reflect the cash flow generated, a good profitable enterprise would be an important facto r to help facilitate and generate cash flow and at the same time debt was guaranteed when it was due. Besides, the test results rev ealed that the financial structure and sales on assets have the inverse effect on the distance to default at the significance level o f 5%. The results also revealed that a group of macro factors had an influence on the distance to default of businesses, including spre ad, GDP and trade balance (via exchange rates). Gross domestic income had certain impacts on the distance to default of businesse s. This was also a basic indicator measuring the national economic cycle.

Template-engaged synthesis of spinel-layered Li_1.5MnTiO_4+<i>δ</i> nanorods as a cathode material for Li-ion batteries

Vu, Ngoc Hung,Unithrattil, Sanjith,Hoang, Van Hien,Chun, Sangeun,Im, Won Bin Elsevier Sequoia 2017 Journal of Power Sources Vol. No.

<P><B>Abstract</B></P> <P>Spinel-layered composites of Li<SUB>1.5</SUB>MnTiO<SUB>4+<I>δ</I> </SUB> were studied for their use as high-energy, low-cost, and environmentally benign cathode materials. The bulk particles showed an attractive specific capacity of up to 250 mAh g<SUP>−1</SUP> at C/10. To improve the performance of this cathode at a high C-rate, a spinel-layered Li<SUB>1.5</SUB>MnTiO<SUB>4+<I>δ</I> </SUB> nanorod was successfully synthesized using a β-MnO<SUB>2</SUB> nanorod template. The nanorod, which had an average diameter of 200 nm and a length of 1 μm, showed specific capacity as high as the bulk particle at C/10. However, owing to a one-dimensional nanostructure with a large effective contact area for Li<SUP>+</SUP> diffusion, the nanorod sample exhibited enhanced capacities 11% (170 mAh g<SUP>−1</SUP>) and 167% higher (80 mAh g<SUP>−1</SUP>) at 1C and 10C rates, respectively, compared to the bulk particles. Moreover, both samples showed good cycle stability and capacity retention of over 85% after 100 cycles at 1C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A promising Li<SUB>1.5</SUB>MnTiO<SUB>4+<I>δ</I> </SUB> cathode: spinel-layered structure with high capacity. </LI> <LI> A Li<SUB>1.5</SUB>MnTiO<SUB>4+<I>δ</I> </SUB> nanorod was synthesized by using a β-MnO<SUB>2</SUB> nanorod template. </LI> <LI> The Li<SUB>1.5</SUB>MnTiO<SUB>4+<I>δ</I> </SUB> nanorods exhibit improved rate performance at high C-rate. </LI> <LI> The structure and electrochemical performances of Li<SUB>1.5</SUB>MnTiO<SUB>4+<I>δ</I> </SUB> were studied. </LI> </UL> </P>