• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.254-256
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• 2005

This paper describes a design of a vector control module for AC motor using high density FPGA. In the proposed vector controller, the vector control blocks including inverse dq transform, space vector PWM and quadrature encoder pulse module are implemented in a FPGA using a VHDL. The simulation results are provided to show the validity of the proposed vector control module.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2701-2703
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• 1999

A new mode of parallel operation of a modular 3-phase AC-DC Flyback converter for high power factor correction along with tight regulation is presented in this thesis. The converter offers input/output transformer isolation for safety, a unity input power factor for minimum reactive power, high efficiency and high power density for minimum weight and volume. Compared with previously developed 3-phase two-stage power converter, the advantage of the proposed converter does not require expensive high voltage and high current devices that are normally needed in popular boost type 3-phase converter. In this paper, a detailed small signal analysis of the modular 3-phase AC-DC flyback converter is provided for control purposes and also experimental results are included to confirm the validity of the analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.12
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• pp.1380-1387
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• 2012

The transmit/receive(T/R) module is a key component in the active phased array system. The brick-type T/R module has been widely used and the miniaturization has been an important factor to get the flexibility of the system configuration. For the miniaturization, multi-function chips(MFC) having a common leg configuration are suitable to reduce the number of required MMICs and a high isolation between transmit and receive paths is necessary for the high gain T/R modules. In this work, we propose a bias timing scheme for the compact T/R module and show the optimum timing based on measurements, in order to improve the feed-back path loop problem and the consequent isolation problem of the common leg configuration. We have implemented high power(7 W/channel) and high T/R gain(35 dB transmit and 30 dB receive gains) within the half size($140{\times}80{\times}16mm^3$) of the conventional T/R modules.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.6 s.97
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• pp.580-585
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• 2005

Two high-efficiency and high power power-combing modules were developed using slotline-to-microstrip transition at V-band. Power-combining modules incorporating two MMIC power amplifiers demonstrated combining efficiencies higher than $80\%$(maximum $86\%$) with saturated output power of 22.96 dBm and 22.81 dBm, respectively. The measurement of back-to-back connected combiners demonstrated insertion loss less than 1.2 dB with return loss better than 15 dB around 60 GHz, respectively.

• Journal of Power Electronics
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• v.8 no.4
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• pp.309-316
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• 2008

In this paper, new topology is proposed that can dramatically reduce the converter power rating and increase the efficiency of total PV system. Since the output voltage of PV module has very wide voltage range, in general, the DC/DC converter is used to get constant high DC voltage. According to analysis of PV characteristics, in proposed topology, only 20% power of total PV system power is needed for DC/DC converter. DC/DC converter used in proposed topology has flat efficiency curve at all load range and very high efficiency characteristics. The total system efficiency is the product of that of converter and that of inverter. In proposed topology, because the converter efficiency curve is flat all load range, the total system efficiency at the low power range is dramatically improved. The proposed topology is implemented for 200kW PCS system. This system has only three DC/DC converters with 20kW power rating each other. It is only one-third of total system power. The experiment results show that the proposed topology has good performance.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.411-417
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• 2009

This paper describes the development of integrated simulator for traction power supply system with GUI (Graphic User Interface). This simulator consists of a lot of calculation modules such as TPS, time table, line constant, and power supply system analysis. Each module has input and output structure respectively. The proposed simulator is tested on both high speed railway line and metropolitan subway line. The test has confirmed the function of the developed simulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.65-69
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• 2010

Supercapacitors as novel energy storage devices between conventional capacitors and batteries, with more specific capacitance and energy densities than conventional capacitors and more power densities than batteries are to be used in many fields. And, social demand on fuel economy and reducing pollution needs equipment of new function such as energy storage system with good power performance, high cyclability and good energy efficiency. Supercapacitor is regarded as one of good alternatives for meeting the requirement of market with excellent power performance and high cyclability. This paper deals with the fundamental characteristics of supercapacitor unit and charge and discharge behavior of supercapacitor module for developing 42V hybrid energy storage system with lead acid battery and supercapacitor in order to adopt to 42V power net for vehicle.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1427_1428
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• 2009

In this paper, we designed and fabricated the ubiquitous thermal sensor unit for high voltage facilities. This sensor unit generates electric power from a current transformer which was mounted in the high voltage wires and transmitted thermal data by using a Zigbee module. We simulated the high voltage facilities that temperature was going up to $80^{\circ}C$ gradually. From the experimental results, it was confirmed that sensibility of the ubiquitous thermal sensor unit is in ranges from $-0.7^{\circ}C$ to $0.3^{\circ}C$.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.4
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• pp.66-74
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• 1997

Recently, high-developed domestic industry and environmental issues demand high-voltage short-pulse power supply(power, voltage, pulse width and repetition rate of 100KW, 150KV, 500ns and 500Hz, respectively) for electron beam process and puolse corona process. In such power supplies magnetic compression circuit can be one of the effectives solutions. In ths study design and operation principle of a pulse-power supply with a three-stage magnetic-compression circuit are described. A good agreement between simulation and experimental results verifies the validity of thescheme. The system delivers energy of 10[J/pulse] at the efficiency of 82%[%].

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.386-387
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• 2013

This paper provides a comparison of high power semiconductor devices in 5MW-class Permanent Magnet Synchronous Generator (PMSG) Medium Voltage (MV) wind turbines. High power semiconductor devices of IGBT module type, IGBT press-pack type, and IGCT of both 4.5kV and 6.5kV are considered in this paper. Benchmarking is performed based on neutral-point clamed 3-level back-to-back type voltage source converter supplied from grid voltage of 4160V. The feasible number of semiconductor devices in parallel is designed through the loss analysis considering both conduction and switching losses under the given operating conditions of 5MW-class PMSG wind turbines, particularly for the application in offshore wind farms. The loss analysis is confirmed through PLECS simulations. The comparison result shows that IGBT press-pack type semiconductor device has the highest efficiency and IGCT has the lowest cost factor considering the necessary auxiliary components.