• Proceedings of the KIPE Conference
• /
• 2003.07b
• /
• pp.860-865
• /
• 2003

Recently, SRMs are used in automobiles for power assistant steering, accessory motion control and traction drives. Especially in the motion control and traction drives, safety and efficiency are of paramount important. The paper describes the essential elements, faced in designing and constructing drive circuits for a switched reluctance motor for automobiles. These converters will be referred to as energy efficient C-dump converter and modified C-dump converter Energy efficient C-dump converter topology eliminate all the disadvantages of the C-dump converter without sacrificing its attractive features, and also provide some additional advantages that have lower number of power devices, full regenerative capability, free-wheeling in chopping or PWM mode, simple control strategy, and faster demagnetization during commutation. The experiments are peformed to verify the capability of proposed control method on 6/4 salient type SRM.

• Journal of the Korean Society for Railway
• /
• v.15 no.2
• /
• pp.116-121
• /
• 2012

DC/DC switching power converters produce DC output voltages from different DC input sources. The converter is 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 DC/DC converter is composed of a PWM-IC (pulse width modulation integrated circuit) controller, a MOSFET (metal-oxide semi-conductor field-effect transistor), an inductor, capacitors, and resistors, etc. PWM is applied to control and regulate the total output voltage. In this paper, radiation shows the main influence on the changes in the electrical characteristics of comparator, operational amplifier, etc. in PWM-IC. In the PWM-IC operation, the missing pulses, the changes in pulse width, and the changes of the output waveform are studied by the simulation program with integrated circuit emphasis (SPICE) and compared with experiments.

• Journal of the Optical Society of Korea
• /
• v.7 no.3
• /
• pp.160-164
• /
• 2003

Materials processing by ultrashort pulsed laser is actively being applied to micromachining technology due to its advantages with regard to non-thermal machining. In this study, materials processing with ultrashort pulses was studied by using the high repetition rate of a 800 nm Ti:sapphire regenerative amplifier. This revealed that the highly precise micromachining of metallic thin film and bulk glass with a minimal heat affected zone (HAZ) could be obtained by using near damage threshold energy. Grooves with diffraction limited sub-micrometer width were obtained with widths of 620 nm on Cr thin film and 800 nm on a soda-lime glass substrate. The machined patterns were investigated through SEM images. We also phenomenologically examined the influence of variations of parameters and proposed the optimal process conditions for microfabrication.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3518-3523
• /
• 2007

An analysis program of specific impulse has been developed for a gas generator cycle rocket engine. The program has been verified by comparing the published performance data of the same cycle engine with RP-1 as fuel. A model for pressure drop of regenerative cooling and film cooling mass flow rate has been suggested to satisfy the necessary cooling condition with Jet-A1 as fuel. The engine mixture ratio is defined by the film cooling mass flow rate and the core mixture ratio. The optimal condition of the combustor pressure and engine mixture ratio has been found for maximum specific impulse.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.619-626
• /
• 2011

In this paper, while electric multiple unit is moving on the rail, the content of measuring and analysing electric power consumption is mentioned. In order to measure the electric power consumption, we developed the power record analysis equipment and installed it the inside of the converter and inverter system to record the electric power consumption measured by voltage sensor and current sensor. Moving on the rail, we analysed traction power used up and regenerative power by using the measuring instrument. We expect that the measured and analysed data will offer basic research material to devise a energy reduction plan and introduce a new EMU system with high efficiency.

• Proceedings of the KIPE Conference
• /
• 2016.07a
• /
• pp.50-54
• /
• 2016

본 논문에서는 전동차의 정차 시 발생하는 회생에너지를 Battery에 충전할 수 있는 전력 변환 장치를 제안한다. 제안된 전력 변환장치는 DC 1500~2000의 가선전압을 분압하여 저압스위칭 소자 적용하며, 고주파 절연 변압기를 적용하였다. 이를 통해 시스템의 스위칭 주파수를 상승시켜 수동 소자들의 사이즈 축소 및 비용 절감 효과를 높이고, 가선과 Battery의 전기적 절연으로 시스템의 안정성을 높였다. 또한 가선 전압 분압을 통해 입력 전압의 변화에 유동적으로 대응할 수 있으며, 시스템의 병렬 구성을 통해 용량의 확장성을 가지게 된다. 제안된 논문에서 제안된 회생에너지 전력 변환 장치는 20[kW] 회생 컨버터 모듈의 5직렬 구성을 통해 100[kW]급 회생 컨버터 유닛을 구성하였으며, 회생 컨버터 유닛을 5병렬로 구성하여 500[kW]급 회생 전력 변환시스템을 구성하였다. 제안된 회생에너지 시스템은 모의 가선 전압 장치 및 Battery 부하를 통해 시스템의 타당성을 검증 한다.

• Proceedings of the KIPE Conference
• /
• 2011.11a
• /
• pp.237-238
• /
• 2011

본 논문에서는 빌딩에 적용되는 DC 배전 시스템에서 회생에너지를 고려한 MRL엘리베이터 구동 시스템을 기술 하였다. DC배전용 3상 PWM 컨버터의 직류단을 공유하여 엘리베이터 구동시스템을 구성한다면, 기존AC 배전 시스템에서 발생할 수 있는 문제점 입력단 역률 제어 및 회생에너지를 추가적인 시스템 구성없이 효율적으로 처리가 가능하다. 본 논문에서는 DC 배전용 MLR엘리베이터 구동시스템의 회생동작 및 입력단 역률 제어의 성능을 시뮬레이션을 통하여 검증하였다.

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

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.626-629
• /
• 2008

In this study, a geothermal power generation system using the Kalina cycle was investigated by the simulation method. The Kalina cycle system can be used for the utilization of a low-temperature heat sources such as geothermal and industrial waste heat that are not hot enough to produce steam. The sea/river water can be considered as a cooling media. A steady-state simulation model was developed to analyze and optimize its performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump were modelled by an isentropic efficiency, while a condenser, an evaporator and a regenerative heat exchanger were modeled by UA-LMTD method with a counter-flow assumption. The effect of the ammonia fraction at the separator inlet on the cycle performance is investigated in detail.

• International Journal of Automotive Technology
• /
• v.5 no.4
• /
• pp.287-295
• /
• 2004

A performance simulator for the fuel cell hybrid electric vehicle (FCHEV) is developed to evaluate the potentials of hybridization for fuel cell electric vehicle. Dynamic models of FCHEV's electric powertrain components such as fuel cell stack, battery, traction motor, DC/DC converter, etc. are obtained by modular approach using MATLAB SIMULINK. In addition, a thermodynamic model of the fuel cell is introduced using bondgraph to investigate the temperature effect on the vehicle performance. It is found from the simulation results that the hybridization of fuel cell electric vehicle (FCEV) provides better hydrogen fuel economy especially in the city driving owing to the braking energy recuperation and relatively high efficiency operation of the fuel cell. It is also found from the thermodynamic simulation of the FCEV that the fuel economy and acceleration performance are affected by the temperature due to the relatively low efficiency and reduced output power of the fuel cell stack at low temperature.