• 한국자동차공학회논문집
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• 제13권1호
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• pp.166-173
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• 2005

A vehicle stability control logic for 4WD hybrid electric vehicle is proposed using the regenerative braking of the rear motor and electronic brake force distribution module. Performance of the stability control logic is evaluated for J-turn and single lane change. It is found from the simulation results that the regenerative braking at rear motor is able to provide improved stability compared with the vehicle performance without my stability control. Additional improvement can be achieved by applying the regenerative braking plus electronic brake farce distribution control. It is expected that the regenerative braking offers additional improvement of the fuel economy as well as the vehicle stability control.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.169-172
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• 2007

HEV용 리튬이온 전지에 대한 연구는 최근에 많은 연구가 진행되고 있으며 그중 고용량 및 저렴한 가격, 환경에 대한 안정성으로 인해 Li-Mn spinel에 대한 성능향상 연구가 많이 이루어지고 있다. 본 연구에서는 Li-Mn spinel의 입자크기에 대한 기초 물성 과 전기적 특성을 측정하여 입자크기가 용량에 미치는 영향에 대한 고찰을 하였다. Li-Mn spinel의 비표면적, C-V 특성, 전기적 용량, coulomb efficiency 등을 통하여 입자의 크기와 전해액, Li의 구동등과 관련하여 용량특성에 향상을 가져오는 입자크기 조건을 정의하였고 그에 따라 온도별로 합성 한 후 입자사이즈에 대한 특성을 나타내었다.

• International Journal of Automotive Technology
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• 제8권6호
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• pp.781-790
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• 2007

Hybrid electric vehicles(HEV) combined with more than one power sources have great potential to improve fuel economy and reduce pollutant emissions. The Integrated Starter Generator(ISG) HEV researched in this paper is a two energy sources vehicle, with a conventional internal combustion engine(ICE) and an energy storage system(batteries). In order to investigate the potential of diesel engine hybrid electric vehicles in fuel economy improvement and emissions reduction, a Dynamic Programming(DP) based supervisory controller is developed to allocate the power requirement between ICE and batteries with the objective of minimizing a weighted cost function over given drive cycles. A fuel-economy-only case and a fuel & emissions case can be achieved by changing specific weighting factors. The simulation results of the fuel-economy-only case show that there is a 45.1% fuel saving potential for this ISG HEV compared to a conventional transit bus. The test results present a 39.6% improvement in fuel economy which validates the simulation results. Compared to the fuel-economy-only case, the fuel & emissions case further reduces the pollutant emissions at a cost of 3.2% and 4.5% of fuel consumption with respect to the simulation and test result respectively.

• Journal of Power Electronics
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• 제7권4호
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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.

• 조명전기설비학회논문지
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• 제20권2호
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• pp.24-28
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• 2006

본 논문은 마이크로 전극 측정 시스템을 사용하여 차세대 신동력 산업인 HEV(Hybrid Electric Vehicle) 및 수소연료전지(PEMFC) 차량용 니켈 수소전지의 전극소재로 사용되고 있는 수소저장합금(Mm : misch metal, $MmNi_{3.55}Co_{0.75}Mn_{0.4}Al_{0.3}$)의 단일 입자에 대해 전기화학적 수소 흡방출 특성 평가를 수행 하였다. 즉 Carbon fiber 마이크로 전극을 합금 입자 한개 위에 전기적인 접촉을 이루도록 조정하고, Cyclic Voltammetry 및 Galvanostatic 충방전 실험을 수행하였다. 그 결과 단일 입자의 방전용량은 약 280[mAh/g]로 이론용량의 약 90[%]의 특성을 보여 주었다. 데이터는. 실제 Ni-MH전지를 구성하는 합금입자 그리고 폴리머 바인더로 구성된 Composite film 전극과 비교 하였다. 추가적으로 합금의 단일 입자에 있어 in situ 미분화 현상을 관찰하였다. 마이크로 전극 측정 시스템에 의한 단일 입자의 전기화학적 평가는 기존의 Composite Film 전극에 비해 수소저장합금에 대해 보다 상세하고 정확한 정보를 쉽게 얻을 수 있었다.

• International Journal of Automotive Technology
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• 제7권4호
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• pp.459-468
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• 2006

The objective of this paper is the development of the forward-looking dynamic simulation model of a hybrid electric vehicle(HEV) for a fuel economy study. The specification of the vehicle is determined based on two factors, engine peak power to curb weight ratio and specific engine power. The steady state efficiency models of the powertrain components are explained in detail. These include a spark ignition direct injection(SIDI) engine, an integrated starter alternator(ISA), and an infinitely variable transmission(IVT). The paper describes the integration of these models into a forward facing dynamic simulation diagram using the AMESim environment. Appropriate vehicle and driver models have been added and described. The controller was designed in Simulink and was combined with the physical powertrain model by the co-simulation interface. Finally, the simulation results of the HEV are compared with those of a baseline vehicle in order to demonstrate the fuel economy potential. Results for the vehicle speed error and the fuel economy over standard driving cycles are illustrated.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.130-131
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• 2012

본 논문은 확장 칼만 필터(EKF)를 이용하여 배터리의 SOC(State-of-Charge) 추정 방법을 제안하였다. EKF는 정확한 모델에서만 제대로 동작 할 수 있다. 따라서, 본 논문은 EKF의 적용을 위해 높은 정확도를 가진 전기적 배터리 모델에 대해 설명한다. 배터리 모델은 4.2V, 40Ah의 리튬폴리머 전지에서 추출되었다. 배터리는 Bulk 커패시터, 두 개의 R-C회로, 직렬 저항을 사용하여 모델링하였다. EKF를 모델에 적용하기 위해 캐패시터 전압은 개방 회로 전압(OCV)을 나타내는데 사용된다. EKF는 충/방전 기기인 Maccor 8500에 의해 얻을 실험 데이터로 테스트하였다. 테스트 결과에서 추정의 오차가 최대 5% 정도로 줄일 수 있다는 것을 보여준다.

• 전기화학회지
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• 제2권4호
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• pp.218-220
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• 1999

EV & HEV의 성능은 다수의 축전지로 구성된 축전지팩의 성능에 좌우된다. 축전지의 열적 특성도 이러한 축전지팩의 성능을 좌우하는 많은 인자중의 하나이다. 특히 축전지의 열적 특성은 차량의 주행성능 및 축전지의 수명주기에 큰 영향을 주기 때문에, 축전지에서 발생되어 나오는 열량은 차량의 주행 모드를 모사한 다양한 조건하에서 가능한 정확히 측정되어야 한다. 또한 EV & HEV용 축전지팩의 열관리 시스템을 설계하기 위해서는 축전지팩내의 축전지에 대한 정확한 열특성 데이터를 필요로 하고 있다. 그러나 기존의 열량계로서는 EV용 축전지를 수용하여 열측정 시험을 하기엔 공동(Cavity)크기가 너무 작다. 이에 EV용 축전지의 열적 특성을 시험하기 위한 열량계를 공동(Cavity)의 크기 $120mm\times75mm\times200mm$로 개발하였다. 열량계의 보정은 0-200 W의 Heat Rate를 발생시킬 수 있는 가상셀(Dummy Cell)을 주문 제작하여 행하였다. 실제 입력 열량에 대한 측정열량의 오차범위는 $2\%$ 이내였고, 측정에 따른 전위 안정성도 2.5 mV 이내였다.

• Journal of Yeungnam Medical Science
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• 제30권2호
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• pp.95-100
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• 2013

Background: This study was performed to investigate the epidemiologic and clinical features of acute respiratory viral infection in hospitalized children. Methods: From 2010 to 2012, we tested nasopharyngeal swab specimen in 1,584 hospitalized children with multiple real-time polymerase chain reactions to identify 10 kinds of respiratory viruses (including influenza virus A, B (FluA, FluB), respiratory syncytial virus (RSV), human metapneumovirus (MPV), adenovirus (AdV), human coronavirus (CoronaV), human enterovirus (HEV), human bocavirus (HBoV), parainfluenza virus (PIV), and human rhinovirus (Rhinovirus)). We analyzed the positive rate, annual and seasonal variations, and clinical features (respiratory tract and non-respiratory tract) according to the retrospective review of medical records. Results: Respiratory viruses were detected from 678 (42.8%) of 1,584 patients. The most common detected virus was RSV (35.0%), and then AdV (19.0%), HEV (18.1%). The critical period of the respiratory viral infection was during the first 12 months of a child's life. PIV increased by 8.4%, 12.1%, and 21.1% annually. Bronchiolitis was most frequently caused by RSV, and croup was frequently caused by PIV. The most common cause of meningitis was HEV. Hepatitis-associated respiratory virus was developed 111 in 678 cases. Conclusion: Although this study was confined to a single medical center for three years, we identified the epidemiology and clinical feature of respiratory viruses in Daegu from 2010 to 2012. Future surveillance will be necessary for annual and seasonal variations.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1075-1080
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• 2015

A hybrid electric vehicle (HEV) powertrain has more than one energy source including a high-voltage electric battery. However, for a high voltage electric battery, the average current is relatively low for a given power level. Introduced to increase the voltage of a HEV battery, a compact, high-efficiency boost converter, sometimes called a step-up converter, is a dc-dc converter with an output voltage greater than its input voltage. The inductor occupies more than 30% of the total converter volume making it difficult to get high power density. The inductor should have the characteristics of good thermal stability, low weight, low losses and low EMI. In this paper, Mega Flux^® was selected as the core material among potential core candidates. Different structured inductors with Mega Flux^® were fabricated to compare the performance between the conventional air cooled and proposed potting structure. The proposed inductor has reduced the weight by 75% from 8.8kg to 2.18kg and the power density was increased from 15.6W/cc to 56.4W/cc compared with conventional inductor. To optimize the performance of proposed inductor, the potting materials with various thermal conductivities were investigated. Silicone with alumina was chosen as potting materials due to the high thermo-stable properties. The proposed inductors used potting material with thermal conductivities of 0.7W/m·K, 1.0W/m·K and 1.6W/m·K to analyze the thermal performance. Simulations of the proposed inductor were fulfilled in terms of magnetic flux saturation, leakage flux and temperature rise. The temperature rise and power efficiency were measured with the 40kW boost converter. Experimental results show that the proposed inductor reached the temperature saturation of 107℃ in 20 minutes. On the other hand, the temperature of conventional inductor rose by 138℃ without saturation. And the effect of thermal conductivity was verified as the highest thermal conductivity of potting materials leads to the lowest temperature saturations.