• 한국기계가공학회지
• /
• 제19권5호
• /
• pp.8-13
• /
• 2020

In this paper, the electric vehicle (EV) and internal combustion engine vehicle (ICEV) are compared for different driving cases. The EV exhibits a lower powertrain efficiency when driven on the aggressive driving cycle than when driven on the moderate cycle. In particular, EV powertrain efficiency is low when the battery state of charge (SOC) is low, but ICEV efficiency increases when the driving cycle changes from the moderate cycle to the aggressive cycle. Based on these results, attempts can be made to increase EV powertrain efficiency. EV charging before the battery power drops to a low charging state can reduce energy consumption by 2.7% for an urban area. Furthermore, ECO driving has a more significant effect on EVs than on ICEVs.

• 한국항공우주학회지
• /
• 제37권11호
• /
• pp.1157-1163
• /
• 2009

본 논문은 과학기술위성3호 리튬이온 배터리의 배터리 운용 시스템에 대해 소개한다. 위성에 전력을 공급하기위한 리튬이온 배터리의 요구조건과 리튬 이온 배터리의 운용 시스템의 전반적인 디자인 방법들을 설명하였다. 더 나아가 이러한 설계 내용들을 검증하기 위하여 검증 모델을 제작하여 기능 테스트들을 수행하였고 이러한 결과 들을 통해서 BMS와 사용된 리튬이온 cell의 성능을 확인하였다.

• 전력전자학회논문지
• /
• 제20권2호
• /
• pp.160-166
• /
• 2015

This study proposes an improved cell balancing circuit for fast equalization among lithium-ion (Li-ion) batteries. A simple voltage sensorless charge balancing circuit has been proposed in the past. This cell balancing circuit automatically transfers energy from high-to low-voltage battery cells. However, the circuit requires a switch with low on-resistance because the balancing speed is limited by the on-resistance of the switch. Balancing speed decreases as the voltage difference among the battery cells decrease. In this study, the balancing speed of the cell balancing circuit is enhanced by using the auxiliary circuit, which boosts the balancing current. The charging current is determined by the nominal battery cell voltage and thus, the balancing speed is almost constant despite the very small voltage differences among the batteries. Simulation results are provided to verify the validity of the proposed cell balancing circuit.

• KEPCO Journal on Electric Power and Energy
• /
• 제5권1호
• /
• pp.25-32
• /
• 2019

K-BEMS 시스템은 태양광과 배터리를 Hybrid PCS 및 EMS로 구성하여, 건물에너지 절감 및 건물 PEAK 부하를 감축하기 위해 도입되었으며, 200여 한전 사옥에 보급되어 시범 운영되고 있다. K-BEMS 시스템을 보다 안정적으로 그리고 효율적으로 운영하기 위한 K-BEMS 연구과제를 2016년 1월부터 2018년 현재까지 전력연구원이 약 3년간 걸쳐 수행하였다. 본 논문에서는 K-BEMS 연구과제에서 수행한 9가지 Scheduling 운전 모드 시험 결과 및 3년간의 Scheduling 운전 결과 발견한 문제점, 그리고 이 문제점 해결을 위해 도입한 제어 알고리즘을 보여 주고 있다. K-BEMS 9가지 Scheduling 자동제어 운전모드 시험을 수행 하였으며, 이 중 3가지 운전모드에서 알고리즘 개선 사항을 발견하였는데, 이들 3가지 경우 모두 배터리 연계 운전과 관련이 있는 것으로 드러났다. 배터리 SOC(State of Charge)는 통상 20% 이상에서 운전되는데, 20% 이하가 되면 배터리 보호 차단기가 동작하여 K-BEMS 자동 운전이 정지되는 현상을 발생한다. 그런데 이 Hybrid 자동제어 모드에서, 배터리 차단기 trip시 태양광 공급마저 중단되는 현상을 발견하였다. 그러므로, Hybrid 공급모드에서 배터리의 차단기가 동작될 경우, 태양광 단독운전으로 자동 전환하여 태양광 공급마저 중단되지 않도록 알고리즘을 재구성하여 자동제어 운전하는 것이 총 에너지 절감 측면에서 반드시 필요한 것으로 분석되었다. 이 때, 계측제어 오차를 감안하여야 하며, 배터리 정지를 너무 보수적으로 의식하여, SOC 운전 Range를 너무 축소해서 운전하면 당초의 피크 부하 저감 이라는 경제성 목표를 달성할 수 없으므로, 효과적인 hybrid 운전(건물 피크 부하 감축 운전)을 위해서는 정지된 SOC 값을 컴퓨터가 기억하고 있다가, 향후 재가동 자동제어 운전시에서는 SOC Range값을 변경 조정 하여 최적 제어 운전하는 자동제어 알고리즘이 PV & Battery hybrid peak load demand control에서 반드시 필요한 것으로 나타났다.

• 한국자동차공학회논문집
• /
• 제13권3호
• /
• pp.35-40
• /
• 2005

In the present study, the influence of operating conditions on fuel economy for hybrid electric vehicle was analyzed. In order to accomplish this, vehicle speed, engine speed, battery current and voltage, SOC (state of charge),motor speed and torque, generator speed and torque, engine coolant temperature etc. were measured in real time. The tests were carried out under different driving cycles which are urban and highway cycles, KOREA CITY cycle and on-road driving, and also under various operating conditions such as different initial SOC, with or without regenerative braking etc.. Generally, conventional gasoline engines show a poor fuel economy at stop and go driving, because braking energy is wasted and the engine is operated in low thermal efficiency regions. However, in case of hybrid vehicles, higher fuel economy can be obtained because of utilizing the maximum thermal efficiency regions of engine, idling stop of engine, and regenerative braking etc..

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2020년도 전력전자학술대회
• /
• pp.218-220
• /
• 2020

배터리 팩을 구성하는 단위 셀들은 전기화학적 특성으로 인해 다양한 내부 파라미터들이 동일한 값을 가지지 않고 편차가 있으며, 편차가 심할 경우 과방전 및 과충전의 원인이 될 수 있다. 기존의 연구된 SOF (State-Of-Function) 알고리즘의 경우 SOC (State-Of-Charge), SOH (State-Of-Health)와 같은 파라미터를 하나의 수식으로 정의하여 배터리 팩의 가용 전력을 예측하는 지표로써 사용되어 왔으나, 본 논문에서 제안하는 새로운 SOF 알고리즘은 배터리 팩 내부의 단위 셀간 파라미터들의 편차를 하나의 수식으로 정의하여 배터리 팩의 안전 상태를 나타낼 수 있는 지표로써 활용한다. SOF 알고리즘을 통해 배터리 팩의 안전 상태를 확인하고 검증하기 위해 21700 NMC(LiNiMnCoO₂) 계열의 고용량 배터리를 14S40P로 구성한 배터리 팩을 사용했다.

• Journal of Electrical Engineering and Technology
• /
• 제13권4호
• /
• pp.1759-1768
• /
• 2018

The energy density, power density and ohm resistance of battery change significantly as results of battery aging, which lead to decrease in the accuracy of the equivalent model. A parameter identification method of the equivale6nt circuit model with 3 R-C branches based on the test database of battery life cycle is proposed in this paper. This database is built on the basis of experiments such as updating of available capacity, charging and discharging tests at different rates and relaxation characteristics tests. It can realize regular update and calibration of key parameters like SOH, so as to ensure the reliability of parameters identified. Taking SOH, SOC and T as independent variables, lookup table method is adopted to set initial value for the parameter matrix. Meanwhile, in order to ensure the validity of the model, the least square method based on variable forgetting factor is adopted for optimizing to complete the identification of equivalent model parameters. By comparing the simulation data with measured data for charging and discharging experiments of Li-ion battery, the effectiveness of the full life cycle database and the model are verified.

• Journal of Electrical Engineering and Technology
• /
• 제12권5호
• /
• pp.1916-1924
• /
• 2017

Fossil oil, as the main energy of transportation, is destined to be exhausted. The electrification of transportation is a sustainable solution to the energy crisis, since electric power could be acquired from the inexhaustible sun, wind and water. Among all the problems that hinder the development of Electric Vehicle (EV) industry, charging issue might be the most prominent one. In this paper, the service process of a charging station with Battery Energy Storage System (BESS) is analyzed by means of $Cram{\acute{e}}r$ - Lundberg model which has been intensively utilized in ruin theory. The service quality is proposed in two dimensions: the service efficiency and the service reliability. The arrival rate and State of Charge (SOC) upon arrival are derived from 2009 National Household Travel Survey (NHTS). The simulations are performed to show how the service quality is determined by the system parameters such as the number of servers, the service rate, the initial capacity, the charge rate and the maximum waiting time. At last, the economic analysis of the system is conducted and the best combination of the system parameters are given.

• 한국수소및신에너지학회논문집
• /
• 제28권3호
• /
• pp.279-286
• /
• 2017

Korea government decides to build one hundred hydrogen refueling stations (HRS) until 2020 and tries to disseminate HRS and boosts HRS market in korea. Naepo HRS in chungnam province has been operated for last one full year of 2016 and recorded 2,520 times full charge for the hydrogen fuel cell powered vehicles and total 6,016 kg hydrogen fueling for the 25 units of hydrogen fuel cell powered vehicles. Raw fuel of hydrogen from tube trailer measured by pressure, converting into weight of hydrogen and shows 19.6% surplus with final charged weight by dispenser. This result is caused measuring errors. Measured charged errors between dispenser and Mass flow meter was determined 13.13%.

• Journal of Mechanical Science and Technology
• /
• 제16권10호
• /
• pp.1287-1295
• /
• 2002

In this work, the fuel economy of a parallel hybrid electric vehicle is investigated. A vehicle control algorithm which yields operating points where operational cost of HEV is minimal is suggested. The operational cost of HEV is decided considering both the cost of fossil fuel consumed by an engine and the cost of electricity consumed by an electric motor. A procedure for obtaining the operating points of minimal fuel consumption is introduced. Simulations are carried out for 3 variations of HEV and the results are compared to the fuel economy of a conventional vehicle in order to investigate the effect of hybridization. Simulation results show that HEV with the vehicle control algorithm suggested in this work has a fuel economy 45% better than the conventional vehicle if braking energy is recuperated fully by regeneration and idling of the engine is eliminated. The vehicle modification is also investigated to obtain the target fuel economy set in PNGV program.