• 전기전자학회논문지
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• 제15권4호
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• pp.324-329
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• 2011

휴대 기기가 고기능화, 다기능화 됨에 따라 다양한 멀티미디어 기능이 요구되면서 배터리를 보다 장시간 이용하면서 더 높은 전력과 에너지가 요구되고 있다. 이에 따라 여러 개의 리튬이온 cell을 연결한 배터리팩이 많이 사용되고 있다. 2개 이상의 cell로 구성된 리튬이온 배터리를 안전하게 사용하기 위해서는 과전압 및 과전류, 고온으로 부터 보호해야 됨은 물론, 수명을 연장하기 위해서 각 cell의 전압을 같게 유지시켜주는 balancing 기능이 반드시 요구된다. 본 논문에서 제안한 IC는 모바일 기기뿐만 아니라 E-bike, 하이브리드 자동차, 전기 자동차 분야에도 적용 가능할 것으로 예상되며, 국내 PMIC 발전에 기여할 것으로 기대된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2357-2364
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• 2011

Diesel locomotive operates the generator with the power from the diesel engine, and it consists of the typical serial-hybrid system which operates the train wheels by converting its generated electric energy into the torque of DC (or AC) motor. However, the technology of locomotives is only focused on trains' controlling power generation mechanism. Hence, it is a current issue that the efficiency of its engine and its generator is relatively lower than that of auto vehicles'. Particularly, since there are no proper equipment to measure the amount of fuel which is essentially necessary for the efficient use of fuel, it is not easy to confirm the instant amount of fuel use as well as the exact average fuel consumption per an hour. Due to those difficulties, it is urgent to develop the device that measures the fuel consumption. Plus, this use of the developed measuring device allows the various and useful analysis relating to the fuel consumption, and this could lead to establishing the efficient driving pattern regarding to fuel saving. This device consists of two flux (fuel level) measuring censors, MCU for calculating the measured values, the information recorder for saving measured values, and the display device for indicating the fuel amount consumed during driving.

• 제어로봇시스템학회논문지
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• 제21권2호
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• pp.137-144
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• 2015

In hybrid or electric vehicles, the hydraulic brake system must be controlled cooperatively with the traction motor for regenerative braking. Recently, a motor driven brake system with a PMSM (Permanent Magnet Synchronous Motor) has replaced conventional vacuum boosters to increase regenerative power. Unlike industry motor controls, additional source codes such as functional safety are essential in automotive applications to meet ISO26262 standards. Therefore, the control logic execution time increases, which also causes an extension of the motor current control period. The increased current control period makes precise motor current control challenging inhigh speed ranges where the motor is driven by high frequency. In this paper, a PWM update strategy and a time delay compensation method are suggested to improve current control and system performance. The proposed methods are experimentally verified.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.26-26
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• 2003

Lithium storage electrodes for rechargeable batteries require mixed electronic-ionic conduction at the particle scale in order to deliver desired energy density and power density characteristics at the device level. Recently, lithium transition metal phosphates of olivine and Nasicon structure type have become of great interest as storage cathodes for rechargeable lithium batteries due to their high energy density, low raw materials cost, environmental friendliness, and safety. However, the transport properties of this family of compounds, and especially the electronic conductivity, have not generally been adequate for practical applications. Recent work in the model olivine LiFePO$_4$, showed that control of cation stoichiometry and aliovalent doping results in electronic conductivity exceeding 10$^{-2}$ S/cm, in contrast to ~10$^{-9}$ S/cm for high purity undoped LiFePO$_4$. The increase in conductivity combined with particle size refinement upon doping allows current rates of >6 A/g to be utilized while retaining a majority of the ion storage capacity. These properties are of much practical interest for high power applications such as hybrid electric vehicles. The defect mechanism controlling electronic conductivity, and understanding of the microscopic mechanism of lithiation and delithiation obtained from combined electrochemical and microanalytical techniques, will be discussed

• 한국분말재료학회지
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• 제16권4호
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• pp.285-290
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• 2009

HDDR treated anisotropic Nd-Fe-B powders have been widely used, due to their excellent magnetic properties, especially for sheet motors and sunroof motors of hybrid and electric vehicles. Final microstructure and coercivity of such Nd-Fe-B powders depend on the state of starting mother alloys, so additional homogenization treatment is required for improving magnetic properties of them. In this study, a homogenization treatment was performed at $900\sim1140^{\circ}C$ in order to control the grain size and Nd-rich phase distribution, and at the same time to improve coercivity of the HDDR treated magnetic powders. FE-SEM was used for observing grain size of the HDDR treated powder and EPMA was employed to observe distribution of Nd-rich phase. Magnetic properties were analyzed with a vibrating sample magnetometer.

• 전력전자학회논문지
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• 제8권4호
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• pp.336-343
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• 2003

일반적으로 브러시리스 직류 전동기의 운전을 위한 회전자의 위치정보와 여자시점 검출을 위해서는 홀센서나 엔코더와 같은 측정 장치가 요구된다. 본 논문에서는 부가적인 검출 장치를 사용하지 않고 각 상의 단자전압을 분석하여 여자 시점뿐만 아니라 회전자의 절대위치를 검출 할 수 있는 센서리스 운전 시스템을 제안한다. 더불어, 제안한 알고리즘을 10k[W]급 전동기에 적용하여 유효성과 타당성을 검증한다.

• Journal of Power Electronics
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• 제18권2호
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• pp.343-355
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• 2018

A wide-voltage-conversion range bidirectional DC-DC converter is proposed in this paper. The topology is comprised of one typical LC energy storage component and a special common grounded asymmetric H-bridge with four active power switches/anti-parallel diodes. The narrow output PWM voltage is generated from the voltage difference between two normal (wider) output PWM voltages from the asymmetric H-bridge with duty cycles close to 0.5. The equivalent switching frequency of the output PWM voltage is double the actual switching frequency, and a wide step-down/step-up ratio range is achieved. A 300W prototype has been constructed to validate the feasibility and effectiveness of the proposed bidirectional converter between the variable low voltage side (24V~48V) and the constant high voltage side (200V). The slave active power switches allow ZVS turn-on and turn-off without requiring any extra hardware. The maximum conversion efficiency is 94.7% in the step-down mode and 93.5% in the step-up mode. Therefore, the proposed bidirectional topology with a common ground is suitable for energy storage systems such as renewable power generation systems and electric vehicles with a hybrid energy source.

• 소성∙가공
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• 제22권3호
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• pp.133-142
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• 2013

Recently, electric vehicles and hybrid cars are being promoted as alternatives to reduce automobile emissions. Generally, thin sheet materials such as aluminum alloy AA300X and cold-rolled steel sheet such as JIS-G-3141 are used for the container for the lithium-ion secondary batteries. In this study, a multi-stage deep drawing process is used to produce a rectangular cup from thin stainless steel sheet material, SUS409L, with an initial blank thickness of 0.4mm for the battery container application. Numerical simulations of the first through the fifth stages for the multi-stage deep drawing with thin SUS409L sheet were conducted using LS-Dyna3D Implicit/Explicit. Special consideration was given to the deformation characteristics due to the normal anisotropy of the sheet material. The numerical simulations were conducted with both isotropic properties and the anisotropic properties of the initial blank material. An unexpected forming failure, barreling in the bottom region of the deep drawn rectangular cup, was observed. This failure mode can be avoided by additional ironing thickness control during the process.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.53-56
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• 2001

This paper has been developed a millimeter-wave radar to prevent car collision. This system needs to progress the problem as follows; (1) Increase of traffic accidents causing damage and injuries due to the increased number of motor vehicles and long distance driving, (2) Need for a device to help drivers who are in trouble due to bad weather conditions. (3) Need for a millimeter-wave radar as obstacles which need to be detected are small. This system is composited with some major technologies, Narrow beams to recognize obstacles or other objects, One-side circuit technology to prevent interference between electric waves, and Parts designed for radar products which are able to transmit millimeter - waves. The system has a various a application Field, Car distance auto-control system, prevent bump collision due to unexpected stoppage of the front car or careless driving, obstacle warning system, Car following system, and industrial and military purposes system. We have a looking forward to propose to develop field tests under various road conditions and hybrid car sensor by combining with other sensors

• Journal of Power Electronics
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• 제13권4호
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• pp.569-583
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• 2013

In this study, the simultaneous use of a multi-level converter (MLC) as a DC-motor drive and as an active battery cell balancer is investigated. MLCs allow each battery cell in a battery pack to be independently switched on and off, thereby enabling the potential non-uniform use of battery cells. By exploiting this property and the brake regeneration phases in the drive cycle, MLCs can balance both the state of charge (SoC) and temperature differences between cells, which are two known causes of battery wear, even without reciprocating the coolant flow inside the pack. The optimal control policy (OP) that considers both battery pack temperature and SoC dynamics is studied in detail based on the assumption that information on the state of each cell, the schedule of reciprocating air flow and the future driving profile are perfectly known. Results show that OP provides significant reductions in temperature and in SoC deviations compared with the uniform use of all cells even with uni-directional coolant flow. Thus, reciprocating coolant flow is a redundant function for a MLC-based cell balancer. A specific contribution of this paper is the derivation of a state-space electro-thermal model of a battery submodule for both uni-directional and reciprocating coolant flows under the switching action of MLC, resulting in OP being derived by the solution of a convex optimization problem.