• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.102-107
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• 2014

Because of high oil prices and emission gas problems, many governments tighten regulation of fuel economy and emission gas. For Passenger car, there are many researches for plug-in hybrid electric vehicles and they are being manufactured. On the other hand, there are few researches for plug-in hybrid electric bus that is heavy commercial vehicle. In this study, analysis of fuel economy for series plug-in hybrid electric bus according to engine operation strategy based on simulation is conducted. Forward simulator is developed using Autonomie. Engine operation strategies consist on constant engine operation strategy and engine on/off operation strategy. Considering the engine operation strategy, results of vehicle speed, engine operating points and fuel economy are obtained and analyzed. As a result, engine on/off operation strategy has more advantage than constant engine operation strategy in terms of fuel economy.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.7
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• pp.854-859
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• 2018

This paper describes the characteristics of a hybrid supercapacitor module for power quality stabilization. Hybrid supercapacitor is an promising energy storage device that positioned between conventional EDLC and Li-ion battery. A cylindrical 7500F hybrid supercapacitor ($60{\times}138mm$) was assembled by using the $Li_4Ti_5O_{12}$ electrode as an anode and activated carbon as a cathode. Considering the ESR and efficiency has been designed to module with 41.6F 480V design results in 180 series combination. In order to determine the characteristics of the hybrid supercapacitor module for power system, hybrid supercapacitor cells were connected in series with active balancing circuit. As a result of measuring the 50kw UPS, it was discharged at the current of 104A~143A during the discharge in the voltage range of 350V~480V, and the compensation time at discharge was measured to be about 30s. These results can be used to stabilization of power quality by applying hybrid supercapacitor module.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.6
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• pp.544-551
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• 2000

In this paper, 3-phase hybrid series active power filter for compensate current harmonics, voltage drop and unbalanced voltage in the network presented. The proposed system is implemented with a space vector modulation voltage source inverter and a high pass filter connected in parallel to the power system. Here the load is six-pulses thyristor rectifier. The phase angle detected in order to generation reference voltage at load terminal is synchronized with the positive sequence component of the unbalanced source by using symmetrical component transformation. The proposed system has an function harmonic isolation between source and load, voltage regulation, and unbalance compensation. Therefore, what the power system is improved quality, the source current is maintained as a nearly sinusoidal waveform and the load voltage is regulated with a rated voltage regardless of the source variation condition. To verify the validity of the proposed compensating system, the computer simulation and experiment are carried out.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.930-939
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• 2009

A bimodal tram is being developed to combine the flexibility of a bus with the punctuality of a train. The propulsion system is a series hybrid type using a set of CNG engine generator and Li-polymer battery. This paper presents the experimental results of the series hybrid propulsion power unit using an active loader which can simulate powering and regenerative braking conditions of the propulsion equipments continuously. The power sharing scheme between PWM converter and a battery pack has been observed. The measurement results of DC link voltage and SOC(State Of Charge) of battery pack are presented.

• Journal of Power Electronics
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• v.13 no.2
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• pp.223-231
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• 2013

A modular three-phase multilevel inverter especially suitable for electrical drive applications has been previously presented. This topology is based on series connection of power cells in which each cell comprised of two inverter legs in series. In this paper, in order to generate the maximum number of voltage levels with reduced number of switches, three algorithms are proposed for determination of the magnitudes of dc voltage sources. In addition, a new hybrid multilevel inverter is proposed that is composed of series connection of the previously presented multilevel inverter and some H-bridges. The proposed topology has been compared with some other presented multilevel inverters. The performance of the proposed multilevel inverter has been verified by simulation and experimental results of a single-phase 39-level multilevel inverter.

• Journal of Power Electronics
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• v.13 no.5
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• pp.757-765
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• 2013

For conventional interleaved two-phase forward converters with a common output inductor, the maximum duty cycle is 0.5, which limits the voltage range and increases the difficulty of the transformer's optimization. A new two-phase hybrid forward converter with series-parallel auto-regulated transformer windings is presented in this paper. With interleaved control signals for the two phases, the secondary windings of the transformers can work in series when the duty cycle is larger than 0.5, and they can work in parallel when duty cycle is lower than 0.5. Therefore, the maximum duty cycle is extended and the turns ratio of the transformer can be optimized. Duty cycle dependent auto-regulated windings result in the steady states of the converter being different in different duty cycle ranges (D>0.5 and D<0.5). Fortunately, the steady state gains of the proposed hybrid converter are identical at different duty cycle ranges, which means a stepless shift between two states. A prototype is built to verify the theoretical analysis. A conventional control loop is compatible for the whole input voltage range and load range thanks to the stepless shifting between the different duty cycle ranges.

• 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.

• Journal of the Korean Data and Information Science Society
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• v.25 no.2
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• pp.431-438
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• 2014

Type I hybrid censoring scheme is the combination of the Type I and Type II censoring scheme introduced by Epstein (1954). Epstein considered a hybrid censoring sampling scheme in which the life testing experiment is terminated at a random time $T^*$ which is the time that happens rst among the following two; time of the kth unit is observed or time of the experiment length set in advance. The likelihood function of this scheme from the Rayleigh distribution cannot be solved in a explicit solution and thus we approximate the function by the Taylor series expansion. In this process, we propose four dierent methods of expansion skill.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.4
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• pp.307-311
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• 2016

Several types of supercapacitors have been developed for energy storage systems. Among them, the hybrid type has advantages such as a large capacitance per weight compared with the electric double-layer capacitator type. In this study, constant current charging and discharging tests were conducted for recently developed hybrid-type supercapacitors. Based on the experimental results, the capacitance and equivalent series resistance were obtained. The capacitance was larger than the designed capacitance at a low current but became small at a high current. In addition, the capacitance depended on the cell voltage. These results can be used to design an energy storage system.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.271-273
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• 1995

Hybrid active filters utilize passive filters to reduce the voltage rating and hence the VA rating of the active filter converter. A novel hybrid active filter topoloty to minimize utility current harmonics at high power levels is presented in this paper. The proposed topology combines both passive and active filters to obtain the lowest converter VA rating as compared to the converter rating in the active filter and the series-active hybrid filter configurations. This is demonstrated with experimental results from a laboratory model. Simulation results showing the effect of passive filter impedance are presented.