• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.211-218
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• 2005

Switched Reluctance Motor(SRM) offers the advantages of simple and robust motor construction, high speed and high efficiency over a wide operating range of torque and speed, excellent controllability. However SRM has the disadvantages of high current harmonics, and low power factor because the required output of speed and torque is produced by the discontinuous and loss of power system, and brings about the incorrect operation of electronic system. This paper deals with an energy efficient converter fed SRM system with the reduced harmonics and improved power factor. The validity of the proposed scheme is verified via experiments. We are implemented the proposed control system using 80C196KC micro-controller.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1145-1148
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• 1999

This paper is introducing a newly developed spark gap switch with dual trigger system, into which the current from the voltage source is injected along wi th the test sequence during the synthetic testing of high voltage circuit-breaker.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.282-284
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• 2006

UV lamp systems have been used for cleaning of display pannels of TFT LCD or Plasma Display Pannel (PDP). However, the needs for high efficient cleaning and low cost made high voltage plasma cleaning techniques be developed and improved. In this paper, 3kW high voltage plasma power supply system was developed for LCD cleaning. The 3-phase input voltage is rectified and then inverter system is used to make a high frequency pulse train, which is rectified after passing through a high-power transformer. Finally, bi-directional high voltage pulse switching circuits are used to generate the high voltage plasma.

• Journal of the Korean Solar Energy Society
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• v.35 no.3
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• pp.49-56
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• 2015

This paper presents a comparative operating characteristics of static var compensator(SVC) and static synchronous compensator(STATCOM) for compensating the reactive power in the Jeju power system. There are two kinds of reactive power compensating systems, which are active and passive system in the applications of the line commutated converter type high voltage direct current (LCC-HVDC). In the Jeju power system, two STATCOMs as active compensating system have been operating. Even though STATCOM has good performance compared with SVC, economical efficiency of former system is not good to the latter system. So, it is necessary to examine the performance and economical efficiency depend on the intention before appling the system. To compare the operating characteristics of two systems in the Jeju power system, simulations have been carried out for case studies that both of the HVDC system have transient state by using PSCAD/EMTDC program.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.36-43
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• 2017

This paper describes a hybrid multi-output three-level DC/DC converter suitable for a wide, high-input voltage range of an auxiliary power supply for a high-power photovoltaic generating system. In a high-power photovoltaic generating system, the solar panel output voltage depends on solar radiation quantity and varies from 450Vdc to 1100Vdc. The proposed hybrid multi-output three-level DC/DC converter, which is an auxiliary power supply, would be used as power source for control printed circuit boards and relay and cooling fans in a high-power photovoltaic generating system. The proposed multi-output ($24V_{DC}/30A$, $230V_{DC}/5A$) hybrid three-level boost converter, which uses an energy recovery snubber, is controlled by variable-frequency and phase-shifted modulations and can achieve zero-voltage switching with all operating conditions of input voltage and load range. Experimental results of a 2kW prototype are evaluated and implemented to verify the performance of the proposed converter.

• Journal of Biosystems Engineering
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• v.26 no.5
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• pp.423-430
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• 2001

The purpose of this study is to develop high-speed rotary tillage system for a power tiller by improving the rotary blade and the power train of transmission. Mechanical structure of gear train of rotary drive of conventional power tiller was simplified so that power can be transmitted directly from second shaft to tilling speed change shaft by rotating freely the transfer gear which changes the direction of rotation of shafts using needle bearing installed into middle shaft. A new gear train suitable for the single-edged rotary blade and high-speed rotary drive was developed with the rotational speed of rotary shaft faster than 7.5% at 1st-speed and 1.4% at 2nd-speed the one of conventional system by changing the numbers of teeth of gears of middle shaft, tilling speed change shaft and PTO shaft. Using the developed gear train for high-speed rotary drive, field tests were performed to compare tillage performances by the developed single-edged blade and by the conventional double-edged blade. The results showed that the performances by the single-edged blade compared with the one by the double-edged blade was improved about 18% in field capacity, about 34% in fuel consumption, and 9.4% in soil crushing ratio. Therefore, it may be concluded that tillage performance by the single-edged blade was improved compared to the one by the conventional blade. Evaluation of the developed system consisting of single-edged blade and gear train for high-speed rotary drive in field revealed that tillage performance of the developed system was similar to the one of field test conducted using the system consisting of single-edged blade and gear train for rotary drive of conventional power tiller However, considering the higher cone index of the upland field where evaluation was carried out compare to the one of the ordinary paddy field, it may be concluded that tillage performance of the developed rotary tilling system better than the one of conventional system.

• Journal of Power Electronics
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• v.3 no.4
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• pp.249-258
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• 2003

This paper presents a high-efficient and cost effective three-phase AC/DC-DC/AC power conversion system with a single two-switch type active Auxiliary Resonant DC Link (ARDCL) snubber circuit, which can minimize the total power dissipation. The active ARDCL snubber circuit is proposed in this paper and its unique features are described. Its operation principle in steady-state is discussed for the three phase AC/DC-DC/AC converter, which is composed of PWM rectifier as power factor correction (PFC) converter, sinewave PWM inverter. In the presented power converter system not only three-phase AC/DC PWM rectifier but also three-phase DC/AC inverter can achieve the stable ZVS commutation for all the power semiconductor devices. It is proved that the proposed three-phase AC/DC-DC/AC converter system is more effective and acceptable than the previous from the cost viewpoint and high efficient consideration. In addition, the proposed two-switch type active auxiliary ARDCL snubber circuit can reduce the peak value of the resonant inductor injection current in order to maximize total system actual efficiency by using the improved DSP based control scheme. Moreover the proposed active auxiliary two-switch ARDCL snubber circuit has the merit so that there is no need to use any sensing devices to detect the voltage and current in the ARDCL sunbber circuit for realizing soft-switching operation. This three-phase AC/DC-DC/AC converter system developed for UPS can achieve the 1.8% higher efficiency and 20dB lower conduction noise than those of the conventional three-phase hard-switching PWM AC/DC-DC/AC converter system. It is proved that actual efficiency of the proposed three-phase AC/DC-DC/AC converter system operating under a condition of soft switching is 88.7% under 10kw output power.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1628-1632
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• 2013

HEP(Head Electric Power) system, supplying 3-phase service power to the coach vehicles, is a kind of special auxiliary power equipment which is boarded on 8200 series electric locomotives in KORAIL. This equipment shares high voltage DC link with a main propulsion converter/inverter systems. It was difficult to use high frequency PWM technique so that GTO has been used as a power device same like the main power system. Due to low PWM frequency(300Hz) of HEP inverter, the output voltage has less power quality comparing to normal SIV(Static Inverter) system. In this paper, an optimal PWM strategy is presented for new IGBT type HEP inverter system. Several PWM techniques were investigated to improve output voltage quality under fixed lower filter inductance and not high PWM frequency. Finally PC simulations have been done to clarify its availability.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.569-575
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• 2003

This paper present a new fully-automated PC-based instrumental system that could quickly measure and analyze the efficiency of switching power supplies for the entire operating range. In the proposed system, we applied an Indirect method for high-voltage low-current measurements and a direct method for low-voltage high-current measurements, in order to obtain a high accuracy with minimum equipment requirement. Compared to the conventional methods, the newly proposed system offers more accurate and much faster real-time assessment of the efficiency with minimum measurement error. The performance and accuracy of the proposed system are verified using a 50 W switching power supply intended for telecommunication applications.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.709-711
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• 2005

Developing fault location system for underground power cable which can detect its fault location exactly require very high speed data acquisition and signal processing capability. We are developing fault location system which is different from conventional fault locator. This fault location system monitor underground power cable by using on-line speed current sensor and if there are an accident, it record its transient signal and calculate fault location by analyzing it. Signals which acquired when power cable fault arise, showed transient characteristics and its frequency band is very hish. So, to develop fault location system, we designed special high speed data acquisition and signal processing board. In this thesis, we describe on data acquisition and signal processing H/W design for fault location system on underground power cable.