• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.11
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• pp.622-627
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• 2002

The power comparison techniques have implemented power measurements, in which a power comparator is used to balance ac against a dc power obtained from known values. The developed power standard system using the comparison techniques consists of dc sources, ac source, control switches, resistive voltage dividers, resistive shunts and a power comparator. The total uncertainty of the power standard system was proved by analysis of the component instruments. Its expanded(k=2) uncertainty is evaluated to be less than 30 uW/VA at unit power factor and 42 uW/VA at power factor 0.5

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.531-538
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• 1999

This paper proposes a fuzzy logic controller(FLC) for DC-DC converters in order to obtain good l perfonnances that can not be achieved by linear control tc'Chniques in the presence of wide parameter v variations. 'While the standard controller uses error and derivative of e$\pi$or, the proposed controller uses state v variables. Such method is ve$\pi$ efficient in case of DC-DC converters and can guarantee both stable s small-signal responses and improved large signal responses. The presented approach method is general and c can be applied to any dc-dc converter topologies. Through the simulations of booster, we verify the pro[Xlsed C control tc'Chnique can give a satisfactory perfonnance.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.499-504
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• 2008

DC substation of urban transit supplies a suitable DC power on electricity vehicles by being supplied from KEPCO. DC substation is verified electrical safety of system through pre-operation inspection on electrical installations to be supplied power from KEPCO. However, because test items and method for DC traction system are unprepared on pre-operation inspection, the general safety and performance verification of DC traction system are very insufficient. Therefore this paper analyze the overseas test examples such as factory equipment tests, factory combined tests and railway tests for the safety and performance verification of DC traction system and present a suitable test items and test standard in domestic.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.235-242
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• 2008

In this paper, a 24-pulse AC-DC converter is designed, modeled, simulated, and developed to feed non-isolated varying loads. The proposed AC-DC converter configuration consists of an auto-transformer based on zigzag connection to overcome current harmonic problems in AC mains. It improves power quality at AC mains and it meets IEEE-519 standard requirements at varying loads. A set of power quality indices on input AC mains and on DC buses for a load fed from 6-pulse and 12-pulse AC-DC converters is also given to compare their performance. It is observed that input current total harmonic distortion(THD) of less than 8% is possible with the proposed topology of AC-DC converter at varying loads.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.238-240
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• 2007

This paper present adaptation method of rail potential test to verify DC railway system's performance and safety. For protection of person and utility caused by rail potential rise, international standard to limit rail potential rise is made and rail potential is tested at the time of plan and construction of DC railway system in foreign country. So, we need rail potential test at the opening time and prepare a continuous monitoring technique of rail potential and a limitation method of rail potential rise. For these, we describe cause of rail potential rise, international standard about rail potential, protection principle, an example of calculation and measurement, and adaptation method for performance test.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.11
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• pp.463-467
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• 2006

A direct current electric power system is one of the most important power source in a metro railway system. As railway system is growing up today, the importance of DC electric power system is emphasized. The study for systemization and standardization of design and operation technique in DC electric power system is undergoing nowadays. For these studies, the development of standard analysis model for metro railway electric power system is required. In this paper, a standard analysis model for metro railway electric power system which is using PSCAD/EMTDC program is proposed. The proposed model is explained and the validity is shown by using the case studies.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.77-83
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• 1992

A primary standard of ac current at low frequency is derived from the standard of dc current by ac-dc transfer instrument. A set of 15 thermal current converters(TCCs) have been constructed as the primary current standards from 5 mA to 20 A at the frequency range of 10 Hz to 100 kHz. It is evaluated that the uncertainties for the maintenance and dissemination of ac current standard are less than 52 ppm up to 20 mA and 20 kHz, 60 ppm up to 100 mA and 20 kHz, and rising to 200 ppm at higher currents and frequencies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.5
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• pp.713-718
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• 2014

DC urban railway power system consists of DC power network and AC power network. The DC power network supplies electric power to railway vehicles and the AC power network supplies electric power to station electric equipment. Recently, because of power consumption reduction and peak load shaving, intelligent measurement of regenerative energy and renewable energy adapted on DC urban railway is required. For this reason, DC smart metering system for DC power network shall be developed. Therefore, in this paper, DC voltage sensor, current sensor, and DC smart meter were developed and evaluated by performance test. DC voltage sensor was developed for measuring standard voltage range of DC urban railway, and DC current sensor was developed as hall effect split core type in order to install in existing system. DC smart meter possesses function of general intelligent electric power meter, such as measuring electricity and wireless communication etc. And, DC voltage sensor showed average 0.17% of measuring error for 2,000V/50mA, and current sensor showed average 0.21% of measuring error for ${\pm}2,000V/{\pm}4V$ in performance test. Also DC smart meter showed maximum 0.92% of measuring error for output of voltage sensor and current sensor. In similar environment for real DC power network, measuring error rate was under 0.5%. In conclusion, accuracy of DC smart metering system was confirmed by performance test, and more detailed performance will be verified by further real operation DC urban railway line test.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.476-477
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• 2008

In this paper, high voltage DC- DC boost converters by stacked structure of power transistors are proposed. These stacked power transistors are tolerant to output voltage higher than the process limit for individual CMOS transistors. The proposed circuits were designed in a standard 3.6V, $0.13{\mu}m$.

• Journal of Power Electronics
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• v.1 no.2
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• pp.107-116
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• 2001

Two AC-DC PWM full-bridge converters that can input current to improve input power factor while performing dc-dc conversion are investigated in this paper. Both converters are simple in that they are similar to the standard PWM full-bridge converter with a diode rectifier/LC low-pass filter input, and both can operate with a simple method of PWM control. In the paper, the operation of the converters is explained and their steady-state characteristics are discussed. The feasibility of the converters and their ability to meet EN61000-3-2 Class D Standards for electrical equipment are shown with results obtained from experimental prototypes. The performance of both converters in terms of dc bus voltage level, input power factor and efficiency is compared and discussed.