• Title, Summary, Keyword: State-of-charge

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Exact analysis for overload of a charge-pump phase-locked loop (Charge-pump 위상 동기 회로의 과부하에 대한 정확한 해석)

  • 최은창;이범철
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.12
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    • pp.3069-3085
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    • 1996
  • This paper shows an accurate charge-pump PLL model which considers the wave-form distortion in high speed operation of charge-pump PLL, the leakage current in loop filter, and a physical limit in charge-pump. With proposed model of charge-pump PLL, overload and stability are derived theoretically and the results are compared to the conventional model. Unlike the ideal charge-pump PLL that simplifies calculations, it is possible to analyze the transient-state and the steady-state at the same time with proposed accurate model. Thus, charge-pump over load, in the transient-state and the stead-state of charge-pump, is accuragely analyzed and the results are confirmed with simulation.

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Space Charge Behavior of Oil-paper Insulation Thermally Aged under Different Temperatures and Moistures

  • Zhou, Yuan-Xiang;Huang, Meng;Chen, Wei-Jiang;Jin, Fu-Bao
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1124-1130
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    • 2015
  • Moisture and high temperature are the most important factors that lead to the ageing of oil-paper insulation, but the research about space charge characteristics of oil-paper insulation does not take the combined effect of ambient temperature, moisture and thermal ageing into account. The pulsed electroacoustic (PEA) method was used to investigate the influence of moisture and temperature on space charge characteristics of oil paper at different ageing stages. The results showed that moisture could speed up formation of space charge in oil paper when water concentration was low, but the formation was restrained if the water concentration was high. At the beginning of thermal ageing, heterogeneous charge accumulation had predominance, but it gradually changed to homogeneous charge injection with ageing. It was believed that moisture concentration could speed up ageing and enhance charge accumulation on one hand, and accelerate or slow down the establishment speed of space charge on the other hand, therefore, charge accumulation type changed with ageing. The more seriously the oil-paper insulation was thermally aged, the deeper the trap energy level was, hence more space charge was trapped, which could be speeded up by increasing the ageing temperature, but the effect of ambient temperature did not fit the Arrhenius law.

Space Charge Behavior of Oil-Impregnated Paper Insulation Aging at AC-DC Combined Voltages

  • Li, Jian;Wang, Yan;Bao, Lianwei
    • Journal of Electrical Engineering and Technology
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    • v.9 no.2
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    • pp.635-642
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    • 2014
  • The space charge behaviors of oil-paper insulation affect the stability and security of oil-filled converter transformers of traditional and new energies. This paper presents the results of the electrical aging of oil-impregnated paper under AC-DC combined voltages by the pulsed electro-acoustic technique. Data mining and feature extractions were performed on the influence of electrical aging on charge dynamics based on the experiment results in the first stage. Characteristic parameters such as total charge injection and apparent charge mobility were calculated. The influences of electrical aging on the trap energy distribution of an oil-paper insulation system were analyzed and discussed. Longer electrical aging time would increase the depth and energy density of charge trap, which decelerates the apparent charge mobility and increases the probability of hot electron formation. This mechanism would accelerate damage to the cellulose and the formation of discharge channels, enhance the acceleration of the electric field distortion, and shorten insulation lifetime under AC-DC combined voltages.

Enhanced Coulomb Counting Method for State-of-Charge Estimation of Lithium-ion Batteries based on Peukert's Law and Coulombic Efficiency

  • Xie, Jiale;Ma, Jiachen;Bai, Kun
    • Journal of Power Electronics
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    • v.18 no.3
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    • pp.910-922
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    • 2018
  • Conventional battery state-of-charge (SoC) estimation methods either involve sophisticated models or consume considerable computational resource. This study constructs an enhanced coulomb counting method (Ah method) for the SoC estimation of lithium-ion batteries (LiBs) by expanding the Peukert equation for the discharging process and incorporating the Coulombic efficiency for the charging process. Both the rate- and temperature-dependence of battery capacity are encompassed. An SoC mapping approach is also devised for initial SoC determination and Ah method correction. The charge counting performance at different sampling frequencies is analyzed experimentally and theoretically. To achieve a favorable compromise between sampling frequency and accumulation accuracy, a frequency-adjustable current sampling solution is developed. Experiments under the augmented urban dynamometer driving schedule cycles at different temperatures are conducted on two LiBs of different chemistries. Results verify the effectiveness and generalization ability of the proposed SoC estimation method.

Coordinated State-of-Charge Control Strategy for Microgrid during Islanded Operation

  • Kim, Jong-Yul;Jeon, Jin-Hong;Kim, Seul-Ki
    • Journal of Electrical Engineering and Technology
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    • v.7 no.6
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    • pp.824-833
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    • 2012
  • In this paper, a coordinated state-of-charge (SOC) control strategy for the energy storage system (ESS) operating under microgrid islanded mode to stabilize the frequency and voltage was proposed. The proposed SOC control loop is made up of PI controller, which uses a SOC state of the energy storage system as an input and an auxiliary reference value of secondary control as an output. The SOC controller changes the auxiliary reference value of secondary control to charge or discharge the ESS. To verify the proposed control strategy, PSCAD/EMTDC simulation study was performed. The simulation results show that the SOC of the ESS can be regulated at the desired operating range without degrading the stabilizing control performance by proposed coordinated SOC control method.

Performance improvement of SOC indicator for electric vehicle using hydrometer (온-라인 비중계를 이용한 전기자동차용 바테리 잔존용량계의 성능개선)

  • 박종건;임영철;박철수;류영재
    • 제어로봇시스템학회:학술대회논문집
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    • pp.423-426
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    • 1996
  • The conditions to be satisfied with SOC(State-of-Charge) indicator installed on the electric vehicle were that it should be used under frequent loading conditions and that it should enable the monitor to adjust to the aging effect. But, the state-of-charge test requires a lengthy stabilization period after discharge cycles and the ampere-hour test requires the knowledge of the battery capacity in terms of amp-hours. However, a monitoring technique combining the state-of-charge test to enable the monitor to adjust to the aging effect with the ampere-hour test to use under frequent loading condition is studied and implemented on a microcontroller-based circuit in this paper. Specially, optical fiber is used to realize hydrometer which is immune to electromagnetic interference and toxic environment and makes it possible to be used in a wide temperature range.

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Improved exciton dissociation and charge transport in energetically cascaded trilayer organic solar cells

  • Seo, Ji-Won;Lee, Sang-Hoon;Lee, Jung-Yong
    • Current Applied Physics
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    • v.17 no.7
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    • pp.924-930
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    • 2017
  • We demonstrate improved exciton dissociation and charge transport in trilayer organic solar cells (OSCs). The interlayer with an intermediate energy level between the main donor and acceptor levels assists the dissociation of excitons in the charge transfer state (CT) and aids the charge transport by increasing a CT state energy. Additionally, the total absorption of the OSC was increased due to the complementary absorption of the inserted interlayer. Experimentally, when a chloroaluminum phthalocyanine (ClAlPc) layer was inserted between copper phthalocyanine (CuPc) and $C_{60}$ in a trilayer OSC, the internal quantum efficiency (IQE) was greatly enhanced by 30% in the wavelength range of 350-550 nm. The enhancement of IQE results in an increase of the power conversion efficiency from 1.30% to 1.69%.

Evaluation of the Effective Charge Density on Low Pressure Nanofiltration with the Separation Characteristics of Monovalent and Divalent Solutes in the Production of Drinking Water

  • Oh, Jeong-Ik;Taro, Urase
    • Environmental Engineering Research
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    • v.16 no.1
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    • pp.29-34
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    • 2011
  • The electric charge on a membrane was investigated by analyzing the experimental rejection of various monovalent and divalent ionic solutes. The characteristics of the separation of ionic solutes using various nanofiltration membranes were obtained from an experimental nanofiltration set-up, with a surface area of $40cm^2$ under the operational pressures between 0.25-0.3 MPa. The state of the membrane electric charge was observed using separation coefficients, i.e., the permeation ratio of monovalent to divalent ions. To confirm the state of the membrane charge observed via the separation coefficient, a calculation using the extended Nernst-Planck equation, coupled with the Donnan equilibrium, assuming different electric charge states of the membrane, was compared with the experimental rejection of ionic solutes. The examination of the characteristics of separation using three types of nanofiltration membranes showed that one of the membranes carried a negative/positive double charge density inside, while other two membranes carried either a positive or negative charge density.

State Space Averaging Based Analysis of the Lithium Battery Charge/Discharge System (상태공간평균에 의한 리튬전지 충방전 시스템의 해석)

  • Won, Hwa-Young;Chae, Soo-Yong;Hong, Soon-Chan
    • The Transactions of the Korean Institute of Power Electronics
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    • v.14 no.5
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    • pp.387-396
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    • 2009
  • The life and performance of lithium battery are greatly influenced by the formation process which is essential in the process of manufacture. Charge/discharge system for the lithium battery are required for the formation process. To simulate such a system in a conventional method takes very long time and requires huge memory space to save data files. So the simulation may be impossible with a general-purpose PC. In this paper, the lithium battery is modelled to a resistor-capacitor serial circuit and the lithium battery charge/discharge system is analyzed and simulated by using state space averaging method. As a result, the simulation time is reduced dramatically and the simulation of the lithium battery charge/discharge system becomes possible on a general-purpose PC within 3 hours. Also, both the charge/discharge characteristics and the time required to charge/discharge of the lithium battery charge/discharge system can be observed. To verify the propriety of resistor-capacitor serial circuit modeling method for lithium battery and the validity of the analysis and simulation based on state space averaging, the lithium battery charge/discharge system is composed and experimentations are carried out.

Advanced Features of Static Inverter and Their Influence on Rail Infrastructure and Vehicle Maintenance

  • Bachmann, G.;Wimmer, D.
    • International Journal of Railway
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    • v.1 no.3
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    • pp.94-98
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    • 2008
  • Static inverters are essential devices onboard of rolling stock. State-of-the-art static inverters have an impact on both rail infrastructure and vehicle maintenance due to their new topology with new features. The paper describes two important aspects as examples of new features available in state-of-the-art static inverters: active input current control and the effects on the rail infrastructure as well as the detection of the state of charge and the state of health of batteries to simplify vehicle maintenance.

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