• Journal of Electrochemical Science and Technology
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• v.8 no.3
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• pp.236-243
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• 2017

A fixed-bed zinc/nickel redox flow battery (RFB) is designed and developed. The proposed cell has been established in the form of a fixed bed RFB. The zinc electrode is immersed in an aqueous NaOH solution (anolyte solution) and the nickel electrode is immersed in the catholyte solution which is a mixture of potassium ferrocyanide, potassium ferricyanide and sodium hydroxide as the supporting electrolyte. In the present work, the electrode area has been maximized to $1500cm^2$ to enforce an increase in the energy efficiency up to 77.02% at a current density $0.06mA/cm^2$ using a flow rate $35cm^3/s$, a concentration of the anolyte solution is $1.5mol\;L^{-1}$ NaOH and the catholyte solution is $1.5mol\;L^{-1}$ NaOH as a supporting electrolyte mixed with $0.2mol\;L^{-1}$ equimolar of potassium ferrocyanide and potassium ferricyanide. The outlined results from this study are described on the basis of battery performance with respect to the current density, velocity in different electrolytes conditions, energy efficiency, voltage efficiency and power of the battery.

• Journal of Power Electronics
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• v.14 no.3
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• pp.468-477
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• 2014

This study proposes an optimized design of a dual active bridge converter for a low-voltage charger in a military uninterrupted power supply (UPS) system. The dual active bridge converter is among various bi-directional DC/DC converters that possess a high-efficiency isolated bi-directional converter. In the general design, the zero-voltage switching(ZVS) region is reduced when the battery voltage is high. By contrast, efficiency is low because of high conduction losses when the battery voltage is low. Variable switching frequency is applied to increase the ZVS region and the power conversion efficiency, depending on battery voltage changes. At the same duty, the same power is obtained regardless of the battery voltage using the variable switching frequency. The proposed method is applied to a 5 kW prototype dual active bridge converter, and the experimental results are analyzed and verified.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.413-414
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• 2014

This paper proposed an optimized design of a dual active bridge converter for a low-voltage charger. The dual active bridge converter among various bi-directional DC/DC converters is a high-efficiency isolated bi-directional converter. In the general design, when the battery voltage is high, the ZVS region is reduced. In contrast, when the battery voltage is low, the efficiency is low due to high conduction loss. In order to increase the ZVS region and the power conversion efficiency, depending on the battery voltage, variable switching frequency method is applied. At the same duty, the same power is obtained regardless of the battery voltage using the variable switching frequency method. The proposed method was applied to a 5kW prototype converter, and the experimental results were analyzed and verified.

• Journal of ILASS-Korea
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• v.28 no.2
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• pp.62-67
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• 2023

Recently, the global automobile industry is aiming for a transition from internal combustion locomotives to zero-emission vehicles. Electric vehicles powered by battery energy can operate at peak performance and improve fuel economy by applying multiple motors or multi-speed transmissions. In order to design a two-speed transmission, it is necessary to evaluate and analyze the application system and performance of electric vehicles. In this study, control performance optimization of a twostage battery electric vehicle equipped with an AMT-based automatic transmission was performed and performance according to control pattern changes was analyzed. In order to improve the operating efficiency of the motor, the shift control that sets the optimal operating point according to the vehicle speed and required torque was derived from the motor efficiency map. The performance of battery energy consumption and transmission loss energy according to the hysteresis interval was analyzed and optimized. The hysteresis interval applied to the optimal shift map acted as a factor in reducing the frequency and loss of shifts. It has been shown that keeping the hysteresis interval at about 4 km/h can reduce energy consumption while reducing the number of shifts.

• Membrane Journal
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• v.33 no.5
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• pp.233-239
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• 2023

The transport properties of membranes used in vanadium redox flow batteries (VRFB) are fundamental in battery performance. High proton conductivity and low vanadium ion permeability must be achieved to achieve high battery performance. However, there is a trade-off relationship between proton conductivity and vanadium ion permeability. So, solving this trade-off relationship is crucial in VRFB development. Also, maintaining high coulombic efficiency, voltage efficiency, and energy efficiency is essential for high-performing VRFB. Recently, various attempts have been made, primarily on composite membranes and SPEEK membranes, to overcome the existing limit of Nafion membranes. VRFB is an essential class of rechargeable battery in composite membranes reviewed here.

• Journal of the Korean Society of Systems Engineering
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• v.20 no.spc1
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• pp.30-44
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• 2024

The DMAIC methodology, which is most familiar to battery production system developers, is partially inadequate in its conformity to utilize battery production system tasks, so it is necessary to improve the function and structure of the methodology, but many battery production system developers use the DMAIC method based on experience, causing side effects such as confusion, delay in tasks, and insufficient performance during tasks. Accordingly, we intend to conduct an empirical study to improve the "efficiency improvement and conformity evaluation method" so that the DMAIC methodology can be used more reasonably and easily. Using the three-stage research model, we derive components that affect conformity through literature and questionnaire surveys in the first stage, use relational characteristics between components in the second stage to confirm the effect on conformity, and use the relational characteristics in the third stage to confirm the possibility of improving efficiency by applying them to the DMAIC methodology in actual cases. Finally, the "Conformity Assessment Index (CAI) equation" based on relational characteristics is established to enable effective conformity evaluation and continuous improvement.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.5
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• pp.677-683
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• 2008

The electric propulsion system us closely related with the economical efficiency of ship operation. Fuel efficiency is mainly decided by propulsion system such as diesel engine, propulsion motor and steam turbine. The hybrid propulsion system for fishing boat consists of diesel engine and battery as propulsion power source. This paper is to design battery capacity according to power consumption with ship operation condition, and to test the power consumption of model ship in the circulating water channel. As a result. it can be known that the optimum ship operation condition affects the fuel efficiency.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.5
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• pp.189-193
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• 2003

Initial irreversible capacity (IIC) can be defined by means of the initial intercalation Ah efficiency (IIE) and the initial irreversible specific capacity at the surface (IICs) with the linear-fit range of the intercalation so as to precisely express the irreversibility of an electrode-electrolyte system. Their relationship was IIC = Qc - Q$_{D}$ = (IIE$^{-1}$ - 1) Q$_{D}$ + IICs in the linear-fit range of IIE. Here, Qc and Qd signify charge and discharge capacity, respectively, based on a complete lithium ion battery cell. Charge indicates lithium insertion to carbon anode. Two terms of IIE and IICs depended on the types of active materials and compositions of the electrode and electrolyte but did not change with charging state. In an ideal electrode-electrolyte system, IIE and IICs would be 100%, 0 mAh/g for the electrode and mAh for the cell, respectively. These properties can be easily obtained by the Gradual Increasing of State of Charge (GISOC).OC).

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.175-181
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• 2016

In the conventional E-bike, a 42 V/10 A Li-ion battery drives a 24 V/10 A BLDC motor via a 6-switch PWM DC/AC inverter. The major problems of the conventional battery-fed motor drive systems are listed as follows. To charge the battery, an external battery charger (adapter) is required, which degrades the portability of E-bike users. In addition, given the high-frequency operation of the motor drive inverter, the switching losses are significant, which degrades the whole power efficiency. High-voltage batteries (42 V) require a complex battery management system (BMS), which degrades the reliability of the battery pack. In this paper, an embedded boost-converter battery charger for E-bikes is proposed. The variable output boost converter, which converts 16.8 V battery voltage to the required variable voltage of the inverter input, can use a low-voltage battery and thus improve the reliability of batteries. By varying the inverter input voltage via boost converter, a DC link voltage control method can be applied to reduce the switching frequency of the inverter, which improves the whole power efficiency. Given that the function of a flyback charger is integrated in the proposed boost converter, the portability of the E-bike user can be maximized by excluding an external adapter. The validity of the proposed circuit will be confirmed by operation mode analysis and simulation. Moreover, experimental results of integrative charger using Li-ion battery and 200 W motor test will be showed with a prototype sample as well.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.131-136
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• 2015

We develop the 60 W class hybrid solar LED street lamp controller. The controller is providing power via an inverter in the day with the least solar cell and battery and charging the battery for the ESS, acts as a power failure, the built-in battery. Rated output of the fabricated LED street lamp is 300 W or greater battery capacity 300 Wh, discharge time 10 hr, LED street lamp efficiency showed a very high level of light efficiency by about 127 lm/W. In addition, as a result of light distribution pattern according to the distance and the light intensity measurement will be able to ensure a very high quality, show the constant brightness in the distance from the road lights 6 m is about 35~40 lux in uniformity ratio. The proposed hybrid solar LED street lamp system showed a high energy capacity of approximately 1.5 to 152.7% power generation efficiency than typical conventional solar street lamp.