• Title/Summary/Keyword: Regenerative braking

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The analysis of power quality characteristics in high speed train through neutral section of catenary system (절연구간운행 고속철도차량 전력품질 특성 분석)

  • Hong, Hyun-Pyo;Choi, Eui-Seong;Lee, See-Bin;Lee, Hee-Soon
    • Proceedings of the KSR Conference
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    • 2011.05a
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    • pp.634-643
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    • 2011
  • The neutral section was installed in order to prevent conflict with different phase angle source in electric railway catenary system. The speed of electric train reduced due to coasting operation by notch off when it passed the neutral section. And, the catenary wire was damaged and the accident might be happened because of the arc generation when the electric train passed the neutral section with notch off condition. The inrush current of main transformer installed tiling train is analyzed during the operation of MCB(main circuit break) passing through the neutral section. The instantaneous waveform of load current were analyzed in case of powering and regenerative braking. Inrush current waveform with run of AC railway train showed that inrush current waveform and harmonics, the inrush current generated from main transformer in train has bad effects on power quality problem. In order to reduce these inrush currents, the MCB is connected when the phase angle of voltage is 90 degree. This paper is to measure inrush current and harmonics in main transformer of high speed train in neutral section of electric railway. This measurement report is used to control minimum inrush current in algorithm and power phase angle.

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Drive-train Jerk Reduction Control for Parallel Hybrid Electric Vehicles (병렬형 하이브리드 전기자동차 구동계의 Jerk 저감 제어)

  • Park, Joon-Young;Sim, Hyun-Sung
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.1
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    • pp.17-24
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    • 2011
  • TMED(Transmission Mounted Electric Device) parallel hybrid configuration can realize EV(Electric Vehicle) mode by disengaging the clutch between an engine and a transmission-mounted motor to improve efficiencies of low load driving and regenerative braking. In the EV mode, however, jerk can be induced since there are insufficient damping elements in the drive-train. Though the jerk gives demoralizing influence upon driving comport, adding a physical damper is not applicable due to constraints of the layout. This study suggests the jerk reduction control, composed of active damping method and torque profiling method, to suppress the jerk without hardware modification. The former method creates a virtual damper by generating absorbing torque in the opposite direction of the oscillation. The latter method reduces impulse on the mated gear teeth of the drive-train by limiting the gradient of traction torque when the direction of the torque is reversed. To validate the effectiveness of the suggested strategy, a series of vehicle tests are carried out and it is observed that the amplitude of the oscillation can be reduced by up to 83%.

A High Efficiency Converter for Battery Hybrid Power System of Electric Vehicles (전기자동차의 배터리 하이브리드 전원시스템용 고효율 컨버터)

  • Tran, Dai-Duong;Lee, Hyun-Hwa;Choi, Woojin
    • Proceedings of the KIPE Conference
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    • 2016.07a
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    • pp.333-334
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    • 2016
  • This paper proposes a new cascoded configuration for hybrid energy storage system (HESS) which consists of batteries and supercapacitor (SC) for Electric Vehicle applications. In this configuration,a resonant LLC converter is interfacedin series with a battery module and it converts a part of the energy from the batteries and transfer it to the dc-link bus. The LLC converter is controlled by a phase-shift angle between the primary and secondary switches to maintain a constant dc-link voltage and obtain soft-switching conditions for all the primary switches. By placing the SC moduleina cascoded concept, the rated voltage of SC can be reduced significantly compared with the conventional topologies. It helps save the cost and reduce the number of SC cells. The proposed configuration can operate with four different modes: feeding load, acceleration, regenerative braking andSC charging. A scaled-down prototype converter (2 kW, 600V output) is designed and tested to verify the advantages of the proposed topology. The maximum efficiency obtained with the proposed topology is 99%.

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A Study on the Reduction of Onboard Transformer Inrush Current of Electric Railway (전기철도 차량 내 변압기의 여자돌입전류 저감에 관한 연구)

  • Huh, Jae-Sun;Kang, Byoung-Wook;Shin, Hee-Sang;Kim, Jae-Chul
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.12
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    • pp.2125-2130
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    • 2010
  • The neutral section on electric railway system is significant sector in order to prevent short circuit of two electric powers. However, while electric trains pass the neutral section, those speed is decreased and the accident of AC electric traction system and the electric train would be occurred. So the countermeasures are urgently needed. The automatic power switching technology system that is current being research and development is system to improve these problems. Because main object of this system is power change using static switch in the neutral section, it's expected to cause a variety of transients. Especially, onboard transformer inrush current for electric railway train can be occurred more than rated current according to switching time. Therefore, the analysis and improvement are needed to ensure the stability of this system. In this paper, we analyze the operating characteristics of the automatic power switching technology system. Especially, it reviews inrush current according to the closing phase angle. And we propose control plan of inrush current considering the case that voltage is maintained due to counter electromotive force and regenerative braking operation of electric railway train. Finally, the proposed control scheme was reviewed using the transient analysis program.

Prediction of the Effect of Cooling Fan Electrification on City Bus (냉각팬 전동화에 따른 시내버스 연비효과 예측)

  • Lee, Yongkyu;Park, Jinil;Lee, Jonghwa
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.6
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    • pp.908-912
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    • 2013
  • Because of their longer operating times and larger size relative to conventional fans, the cooling fans mounted in buses consume larger amounts of energy. Most of the cooling fans mounted in a bus are connected to the engine by a viscous clutch. A viscous cooling fan's speed is determined by its fluid temperature, which is affected by the air flow through the radiator. The fan does not react immediately to the coolant temperature and in doing so causes unnecessary energy consumption. Therefore, the fuel economy of buses using viscous fans can be improved by changing to an electric cooling fan design, which can be actively controlled. In addition, electric power consumption is increased by using electric cooling fans. Thus, when electric fans are applied in conjunction with the alternator management system (AMS), the fuel economy is further enhanced. In this study, simulations were performed to predict coolant temperature and cooling fan speeds. Simulations were performed for both viscous and electric cooling fans, and power consumption was calculated. Additionally, fuel economy was calculated applying both the alternator management system and the electric cooling fan.

Thermal Design and Analysis Evaluation of ISG Motor for Hybrid Electric Vehicles considering High-speed Driving Condition (고속 운전조건을 고려한 하이브리드 자동차용 ISG 모터 방열설계 및 해석 평가)

  • Kim, Sung Chul
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.1
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    • pp.59-64
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    • 2014
  • Integrated Starter Generator (ISG) system improves the fuel economy of hybrid electric vehicles by using idle stop and go function, and regenerative braking system. To obtain the high performance and durability of ISG motor under continuously high load condition, the motor needs to properly design the cooling system (cooling fan and cooling structure). In this study, we suggested the enhanced design by modifying the thermal design of the ISG motor and then analyzed the improvement of the cooling performance under high-speed condition and generating mode by CFD simulation. The temperatures at the coil and the magnet of the enhanced model were decreased by about $4^{\circ}C$ and $6^{\circ}C$, respectively, compared to those of the conventional model. Therefore, we verified the cooling performance enhancement of the novel thermal design in the case of core loss increment due to the higher speed condition.

A Study on Performance Improvement of Hybrid Energy Storage System for Mild HEV (마일드 하이브리드 차량용 복합형 에너지 저장장치의 성능개선에 관한 연구)

  • Lee, Back-Haeng;Shin, Dong-Hyun;Kim, Hee-Jun
    • 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.

A Study on Effective Control Methodology for DC/DC Converter (DC/DC 컨버터의 효율적인 제어기법 연구)

  • Lho, Young Hwan
    • Journal of Institute of Control, Robotics and Systems
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    • v.20 no.7
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    • pp.756-759
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    • 2014
  • DC/DC converters are commonly used to generate regulated DC output voltages with high-power efficiencies from different DC input sources. The converters can be applied in the regenerative braking of DC motors to return energy back to the supply, resulting in energy savings for the systems at periodic intervals. The fundamental converter studied here consists of an IGBT (Insulated Gate Bipolar mode Transistor), an inductor, a capacitor, a diode, a PWM-IC (Pulse Width Modulation Integrated Circuit) controller with oscillator, amplifier, and comparator. The PWM-IC is a core element and delivers the switching waveform to the gate of the IGBT in a stable manner. Display of the DC/DC converter output depends on the IGBT's changes in the threshold voltage and PWM-IC's pulse width. The simulation was conducted by PSIM software, and the hardware of the DC/DC converter was also implemented. It is necessary to study the fact that the output voltage depends on the duty rate of D, and to compare the output of experimental result with the theory and the simulation.

Algorithm for the correction of errors on metering method in the scott transformer by regenerative braking in high speed trains (고속전철 회생 제동시 스코트 변압기의 계량오차 보정 알고리즘)

  • Yun, DongHyun;Shin, Dong-Gu;Choi, Eui-Seong;Cha, HanJu
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.1587-1588
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    • 2015
  • 일반적으로 국내의 대부분의 전기철도는 단상 교류식이므로 전력계통의 3상 154[kV]을 스코트 변압기를 통해 단상 55[kV]로 변환하여 단상 교류로 공급받는다. 전기철도는 기동 특성 및 제동 특성에 따라 부하의 급증과 급감, 임의의 한 급전 구간 내에 운행 일정 중복으로 다수의 전기철도 차량이 운행될 경우 상호간 전기적 특성이 수시로 변한다. 이와 같은 전기적 특성이 수시로 변하는 전력량은 스코트 변압기에서 전력량을 측정하게 된다. 스코트 변압기 1차측 3상 전력이 2차측 단상 전력으로 변환하는 전기기기이며, 전동차가 제동시 회생전력이 발생되는데 이로인해 스코트변압기의 1차측과 2차측 위상이 다르게 발생되어 계량오차가 발생되는 문제점이 있다. 따라서, 본 논문에서는 계량오차의 문제점을 해결하기 위해, 스코트 변압기 2차측 기준으로 전압과 전류의 위상차를 계산하여 회생전력과 수전전력을 정확하게 계량하여 오차를 판단하고 보정하는 알고리즘을 제시하고자 한다.

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A Study on Ripple Current Reduction of Interleaved Bi-directional DC-DC Converter for Traction Characteristic of Railway Vehicle (철도차량 견인특성을 고려한 인터리브드 양방향 DC-DC 컨버터의 리플전류 저감에 관한 연구)

  • Lee, Hwan;Jung, No-Geon;Kim, Jae-Moon
    • 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.