• Journal of Institute of Control, Robotics and Systems
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• v.18 no.4
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• pp.371-374
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• 2012

DC/DC switching power converters produce DC output voltages from different stable DC input sources regulated by a bi-polar transistor. The converters can be used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The voltage mode DC/DC converter is composed of a PWM (Pulse Width Modulation) controller, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an inductor, and capacitors, etc. PWM is applied to control and regulate the total output voltage. It is shown that the output of DC/DC converter depends on the variation of threshold voltage at MOSFET and the variation of pulse width. In the PWM operation, the missing pulses, the changes in pulse width, and a change in the period of the output waveform are studied by SPICE (Simulation Program with Integrated Circuit Emphasis) and experiments.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.348-354
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• 2000

An accumulator in hydraulic systems stores kinetic energy during braking action, and then that controls a hasty surge pressure. This study suggests a method ot determine the capacity of the accumulator to control surge pressure to a desired degree. A mathematical dynamic model of the system was derived and the parameters in the model were identified from experimental data. A series of computer simulation were done for the brake action. The results of the simulation work were compared with those of experiments. These results of the computer simulation and experiments shows that the proposed design method of the accumulator was verified in controlling surge pressure of the system.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.204-212
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• 2010

Currents which are generated at both ends of drive motor by operating brake pedal when subway train is driving, will generate the reviltalization actual effect if they are not used immediately. So there exist rolling stock established Dynamic braking annex for the purpose of stable brake performance in case there are no retrogress train around or no stable wiring voltage.Therefore 55% of entered energy are consumed in subway train. 45% are used in down gradient section or for regeneration energy and among them 25% are used for another train's retrogression through the wiring. So to reduce reviltalization method keeping the existing system, substation's service voltage should be declined about 5%. And then it will ease off excessive wiring voltage rise. And there need energy reduction by flexible service voltage adjustment and study for energy consumption efficiency in the subway.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.38-48
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• 2007

this paper analyses how much acceleration and deceleration of urban rail vehicle should be applied and how to choose an operation mode to minimize energy consumption when train runs between stations within the fixed operation time. The decided operation pattern satisfying the minimum energy consumption becomes a target trajectory and a basis for the controller design criteria. To make this goal it grasps the characteristics of urban rail vehicle, realize operation energy model of urban rail vehicle and verity the accuracy of embodied model the Matlab simulation with the same operation result of real route. It searches for operation pattern to minimize operation energy by changing the acceleration and deceleration on the imaginative route and proposes operation pattern minimizing energy consumption by applying real operation data between stations of Seoul Metropolitan Subway Line 6.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1763-1769
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• 2007

To improve the cycle-life and efficiency of an energy storage system for HEV, a dynamic control system consisted of a switch between a battery and an ultracapacitor module is proposed, which is appropriate for mild hybrid vehicle with 42V power net. The switch can be controlled based on the status of the battery and the ultracapacitor module, and a control algorithm that could largely decrease the number of high charging current peak is also implemented. Therefore the cycle life of the battery can be improved such that it is suitable for a mild hybrid vehicle with frequent engine start-stop and regenerative-braking. Also, by maximizing the use of the ultracapacitor, the system efficiency during high current charging and discharging operation is improved. Finally, this system has the effects that improves the efficiency of energy storage system and reduces the fuel consumption of a vehicle. To verify the validity of the proposed system, this paper presented cycles test results of different energy storage systems: a simple VRLA battery, hybrid energy Pack (HEP, a VRLA battery in Parallel with Ultracapacitor) and a HEP with a switch that controlled by energy management system (EMS). From the experimental result, it was proved the effectiveness of the algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.6
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• pp.487-497
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• 2010

This paper describes the PSIM simulator for the analysis of the series type HEV operation. The traction force of the series type HEV of which engine is electrically coupled with a traction motor is supplied from the traction motor only. The rating of each power train components, such as gear, motor, ESS, ICE/generator, is designed with the Energy-Based Modeling method and the Electrical Peaking Hybrid(ELPH) method. Under driving cycle, the designed series HEV is evaluated with the developed PSIM simulator. A comparison between the conventional braking and the regenerative braking is performed with the average motor input power. And the fuel economy analysis is carried out on the basis of the simulation results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.4
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• pp.733-739
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• 2017

Research on fuel cell systems attracting attention as an environmentally friendly energy source has been actively conducted. And research is being conducted on railway vehicles that use direct current power generated by a fuel cell as an energy source. In this paper, a two-phase interleaved bidirectional DC-DC converter has been proposed which can supply electric energy of a battery to a traction motor during powering and charge the battery with regenerative energy during braking. Therefore, the topology of the energy storage system applied to the railway vehicle was analyzed, and the simulation was performed by constructing the power conversion system by this topology. Experiments were also conducted through hardware design and fabrication based on the simulation analysis results, and the validity of the hardware implementation was verified.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.97-104
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• 2004

As a device that returns surplus energy, regenerated from trains to d.c. source, to a.c. system and reuses it, the thyristor Inverter has been widely used. Because the conventional thyristor inverter is a unidirectional phase-controlled device, it Is Impossible to control the power factor of its output. Moreover, harmonics emission is high and it needs to take a additional filter. In this paper, to solve the problems stated above, the inverter, which can control real and reactive power by adopting IGBT modules as switching elements and being controlled by means of space vector PWM, is developed. Considering high economical efficiency and reliability in order to apply to the system for commercial use, the developed inverter is equipped with fully digital control system and low pass filter, and reduces harmonics and has compact size. The detail description about the developed inverter is stated in various respects: design criteria, technical description, power circuits, control techniques, the developed system, test results, etc.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.534-537
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• 2008

하이브리드자동차의 연료소비율 시험 시 초기 SOC 조건에 따른 SOC와 연비 변화 특성을 파악하기 위해 2종의 차종을 선택하여 UDDS 모드주행 실험을 실시하였다. 실험결과 Strong type 자동차는 주행시작 약 550초 경과 후 SOC 52 $\sim$ 54%로 수렴하였다. 또한 일반 시가지 주행조건에서는 SOC를 50$\sim$55 % 범위에서 제어함을 알 수 있으며, 초기 SOC 조건에 따라 연비는 약 79%의 편차가 나타났다. 이는 저속구간에서 순수 전기자동차 구동이 구현됨으로써 SOC 70%에서 큰 연비 상승 효과가 나타나는 것으로 판단 된다. Mild type 자동차는 연비가 초기 SOC 조건에 따라 약 5%의 편차가 나타남을 알 수 있었으며, SOC 변화특성은 배터리 충전상태에 따라 충전량 제어는 이루어지나 가속 시 어시스트만 이루어지는 시스템적 특성상 효율적인 SOC 제어가 이루어지지 않아 연비에는 큰 영향을 주지 않는 것으로 생각된다.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.198-200
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• 2006

In this paper, three types of power control strategies for controlling a Fuel Cell Hybrid Electric Vehicle(FCHEV) are studied in view of fuel economy. The FCHEV has become one of alternatives for future vehicles since it does emit water only without any exhaust gas while it has a high well-to-wheel efficiency together with an energy saving due to regenerative braking. However, it has also several disadvantages such as the complexity of vehicle system, the increased weight and the extra battery cost. Among various power control strategies, a static power control strategy, a power assist control strategy and a fuzzy logic-based power control strategy are simulated and compared to show the effectiveness of each method.