• 한국전기화학회:학술대회논문집
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• 1998.12a
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• pp.7-27
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• 1998

In order to design capacity of lithium ion battery, some calculations were carried out based on the characteristics of materials by the given battery shape and dimension. The principle of design was built by the interpretation of the correlation of material, electrochemical and battery factors. Parameters of materials are fundamental physical properties of constituent such as cathode. separator, anode, current collectors and electrolyte. Electrochemical factor includes potential pattern as a function of specific capacity, specific discharge capacity(or initial irreversible specific capacity or Ah efficiency) as a function of specific charge capacity and material balancing. Parameters of battery are dimension, construction hardware and performance. Battery capacity was simulated for a lithium cobalt dioxide as cathode and a hard carbon as anode to achieve 1100 mAh for the charge limit voltage of 4.2V, the weight ratio(+/-) of 2.4 and ICR18650. A fabricated test cell (ICR18650) which have weight ratio(+/-) of 2.4 discharged to 1093 mAh for the charge limit voltage of 4.2V. The sequential discharge capacity show good correspondence with designed capacity.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.387-388
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• 2020

본 논문은 패시브 셀 밸런싱과 액티브 셀 밸런싱의 에너지 손실 비교에 관한 연구내용이다. 패시브 셀 밸런싱은 저항을 이용하여 과충전된 셀의 에너지를 소모하는 방식이며 액티브 셀 밸런싱은 SSC(Single Switched Capacitor) 구조를 이용하여 높은 에너지 셀의 에너지를 낮은 에너지 상태의 셀로 전달하는 방식이다. 높은 셀과 낮은 셀의 SOC(State Of Charge)의 차이가 5% (0.085 V)일 때 ∆SOC = 3% (∆V = 0.051 V)로 줄이기 위해 패시브 셀 밸런싱과 액티브 셀 밸런싱을 하여 두 셀 밸런싱의 에너지 손실 차이를 시뮬레이션과 실험을 통하여 비교한다.

• Journal of Power Electronics
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• v.7 no.4
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• pp.343-352
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• 2007

This paper proposes a modularized charge equalization converter for hybrid electric vehicle (HEV) lithium-ion battery cells, in which the intra-module and the inter-module equalizer are Implemented. Considering the high voltage HEV battery pack, over approximately 300V, the proposed equalization circuit modularizes the entire $M^*N$ cells; in other words, M modules in the string and N cells in each module. With this modularization, low voltage stress on all the electronic devices, below roughly 64V, can be obtained. In the intra-module equalization, a current-fed DC/DC converter with cell selection switches is employed. By conducting these selection switches, concentrated charging of the specific under charged cells can be performed. On the other hand, the inter-module equalizer makes use of a voltage-fed DC/DC converter for bi-directional equalization. In the proposed circuit, these two converters can share the MOSFET switch so that low cost and small size can be achieved. In addition, the absence of any additional reset circuitry in the inter-module equalizer allows for further size reduction, concurrently conducting the multiple cell selection switches allows for shorter equalization time, and employing the optimal power rating design rule allows fur high power density to be obtained. Experimental results of an implemented prototype show that the proposed equalization scheme has the promised cell balancing performance for the 7Ah HEV lithium-ion battery string while maintaining low voltage stress, low cost, small size, and short equalization time.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.141-142
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• 2016

본 논문에서는 OBC 전원장치를 이용하여 전기 자동차의 배터리를 충전함에 있어 배터리의 셀 밸런싱을 고려한 충전 기법에 대하여 기술한다. 기존의 OBC 전원장치의 경우 배터리의 온도를 무시한 충전기법이 사용되며, 온도특성에 따라 배터리 수명이 달라지는 문제점을 발생시킨다. 따라서 배터리의 셀 밸런싱을 통해 배터리의 온도를 일정하게 유지하여 배터리 수명 연장시킨다.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.3
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• pp.405-412
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• 2023

With the development of drone and ICT convergence technology, the use of underwater drones such as leisure underwater drones such as underwater exploration for fishing and industrial drones such as bridge piers is increasing. Existing motor controllers are suitable for aerial drones and these can increase the completeness of underwater drones and their reliability in motor control by developing BLDC motor controllers dedicated to underwater drones. By developing a battery management system (BMS) exclusively for underwater drones, battery stability was ensured by checking the state of charge, checking the state of discharge, adjusting cell balancing, and implementing high/voltage protection functions.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.701-710
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• 2017

This paper presents a five-level PWM inverter using series and parallel connection of voltage sources. The alternative connection is done by an auxiliary circuit consisted of a switch, three diodes, and two batteries. The auxiliary circuit is located between input dc voltage source and H-bridge cell. Thanks to the auxiliary circuit, the proposed inverter synthesizes five-level output voltage in an effective way. Topologically both batteries are charged and discharged in the same rate, so it does not need to apply battery voltage balancing control method. Theoretical analysis of the proposed inverter is verified by computer-aided simulation and experiment based on a prototype of 1kW.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.577-579
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• 2008

현재 우리사회는 친환경을 요구하는 시대로 접어들었다 세계적인 추세도 같은 방향으로 흐르고 있으며, 이미 미국, 영국, 프랑스, 이태리, 일본 등의 선진국에서는 자연 친화적, 경제적 실리 추구 및 편리성을 추구하면서 청정 에너지를 사용하는 "미래형 이동수단"에 큰 관심을 갖고 우리보다 한발 앞서 나가고 있다. 이중 전기자전거는 배터리를 통해 무공해, 무소음이라는 장점을 가지고 있으며, 유지관리비가 거의 들지 않고 교통체증을 완화시켜주며, 주차에 신경쓰지 않아도 되어 교통수단에 혁신을 가져다 줄 것이라 생각된다. 본 논문에서는 소형이동 수단인 전기자전거에 채용되는 고출력 리튬이온 배터리팩의 관리시스템을 개발하였으며, 기존의 MCU를 채용하는 제품에서의 문제점이었던 소비전류는 크게 저감하고 셀 밸런싱(Cell Balancing), 온도보호(OTP, Over Temperature Protection) 등의 추가기능은 충실히 수행할 수 있으면서도 저가의 전기자전거용 배터리관리시스템(BMS, Battery Management System)을 개발하였다.

• Carbon letters
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• v.1 no.3_4
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• pp.148-153
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• 2001

The initial irreversible capacity, $Q_i$, is one of the parameters to express the material balancing of the cathode to anode. We introduced new terms, which are the initial intercalation Ah efficiency (IIE) and the initial irreversible specific capacity at the surface ($Q_{is}$), to express precisely the irreversibility of an electrode/electrolyte system. Two terms depended on kinds of active-materials and compositions of the electrode, but did not change with charging state. MPCF had the highest value of IIE and the lowest value of $Q_{is}$ in 1M $LiPE_6$/EC + DEC (1 : 1 volume ratio) electrolyte. IIE value of $LiCoO_2$ electrode was 97-98%, although the preparation condition of the material and the electrolyte were different. $Q_{is}$ value of $LiCoO_2$ was 0~1 mAh/g. MPCF-$LiCoO_2$ cell system had the lowest of the latent capacity. $Q_{is}$ value increased slightly by adding conductive material. IIE and $Q_{is}$ value varied with the electrolyte. By introducing PC to EC+DEC mixed solvent, IIE values were retained, but $Q_{is}$ increased. In case of addition of MP, IIE value increased and $Q_{is}$ value also increased a little.

• Journal of Biosystems Engineering
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• v.43 no.2
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• pp.94-102
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• 2018

Purpose: In this study, a maintenance free super-capacitor battery charging system based on the photovoltaic module, to be used in agricultural electric carriers, was developed and its charging characteristics were studied in detail. Methods: At first, the electric carrier system configuration is introduced and the electric control components are presented. The super-capacitor batteries and photovoltaic module used in the experiment are specified. Next, the developed charging system consisting of a constant current / constant voltage Buck converter as the charging device and a super-capacitor cell as a balancing device are initiated. The proposed circuit design, a developed PCB layout of each device and a proportional control to check the current and voltage during the charging process are outlined. An experiment was carried out using a developed prototype to clarify the effectiveness of the proposed system. A power analyzer was used to measure the current and voltage during charging to evaluate the efficiency of the energy storage device. Finally, the conclusions of this research are presented. Results: The experimental results show that the proposed system successfully controls the charging current and balances the battery voltage. The maximum voltage of the super-capacitor battery obtained by using the proposed battery charger is 16.2 V, and the maximum charging current is 20 A. It was found that the charging time was less than an hour through the duty ratio of 95% or more. Conclusions: The developed battery charging system was successfully implemented on the agricultural electric carriers.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.115-123
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• 2007

This paper presents the conceptual design of the electrical power system using Li-ion cell technology for a satellite application. Compared to a conventional NiCd cell, a Li-ion cell has a lot of advantages such as an energy density, mass and a volume. Normally, a Li-ion cell has three times than conventional NiCd cells in a capacity such as a cell voltage. The normal voltage of a NiCd cell is around +1.2V and a Li-ion cell could be in +3.6V. However, the handling procedure for a Li-ion cell in charge and discharge might be difficult than a conventional NiCd cell, which means that the charge and discharge of each cell should be monitored and controlled by electrical circuits to prevent an over-charge and over-discharge. Therefore, in this paper we propose the design consideration and the characteristics of a Li-ion cell during charging and discharging battery packs in the point of view of electrical power system.