• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.487-488
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• 2016

In this paper, a new active circuit for common-mode voltage (CMV) cancellation in three-level NPC (neutral-point clamped) inverters is proposed, which can avoid the saturation of the common-mode transformer (CMT). The proposed circuit utilizes an additional three-level leg to produce the compensating CMV of the NPC inverters, which eliminates the CMV of the inverter through the CMT.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.303-306
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• 2002

This paper presents a novel method for measuring the ground impedance in grounding systems. A square wave current was injected to the main grounding grid through auxiliary electrode, and the test current and ground potential rise(GPR) were measured using the band-pass filter. Ground impedance was calculated from the sinusoidal waveforms of the test current and GPR in frequency range of 20~2100Hz. Also the resistance and reactance component of ground impedance were analyzed.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.595-598
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• 1999

A new of the automotive High Intensity Discharge(HID) lamp ballast systems is proposed. Proposed scheme is consisted of the high frequency DC-DC converter and low frequency DC-AC inverter as same as conventional HID ballast system. But this system separates ignition voltage from dc link voltage, which results to used the lower voltage rating power devices for HID lamp ballast system compared with conventional system. As a result, proposed system has a lower cost and higher efficiency.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.3
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• pp.51-57
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• 1997

A new current controlled PWM technique with N.P.C structure is proposed in this paper. A current controlled PWM technique with neutral-point-clamped pulsewidth modulation inverter composed of main switching devices which operates as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential is described. This inverter output contains less harmonic content as compared with that of a conventional current controlled PWM type. In addition, the proposed current controlled PWM technique has lower switching frequency than that of conventional current controlled PWM technique at the same current limit. Two inverters are compared analytically. The improved voltage waveform of current controlled PWM with N.P.C structure is analyzed and the performance is investigated by the computer simulation.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.137-143
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• 2013

This paper presents development of variable speed generation (VSG) system with energy saving function. The rubber tyred gantry crane (RTGC) requires the power from diesel-engine. Significant fuel savings by reducing the engine speed can be achieved, because all of operation modes except hoisting are required lower power than rated value of engine. When low speed operation output voltage of generator is decrease until acceptable range of motor driver inverters and auxiliary load supplier. According to power demand engine speed is varying from 20 to 60Hz, and voltage is varying between 210Vac and 480Vac. When idle mode or low power operation dc/dc converter operates by constant output voltage control and inverters dc site voltage is compensated by it. This paper proposed 3-phase interleaved boost converter which has the same structure as the commercially available 3-phase inverter and current sharing capability. 400kW interleaved converter is designed and a performance of converter is evaluated through several experiments with a RTGC system. Energy saving VSG system can cut down fuel consumption by 36% and 21.3% at idle and unidirectional load operations.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.449-454
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• 1999

A new scheme of the automotive High Intensity Discharge (HlD) lamp ballast systems is proposed. The p proposed scheme consists of the high frequency IX DC converter and the low frequency DC-AC inverter, like t that the conventional HID ballast system. However, this system separates the input voltage of the ignitor from t the dc link voltage, which results in the use of lower voltage rating power devices for the HID lamp ballast s system, comparlu with convention띠 system. As a result, proposed system has a lower cost and higher e efficiency. This paper presents th$\varepsilon$ design and anlaysis of the propoSlU ballast and some 앉아、nmental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.3
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• pp.133-139
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• 2002

In this paper, a prototype of an active auxiliary quasi-resonant DC link (QRDCL) snubber assisted voltage source bidirectional power converter (AC to DC and DC to AC) operating at zero voltage soft-switching (BVS) PWM nlode is presented for a Battery Energy Storage System (BESS). The operating principle of this QRDCL circuit and multifunctional control-based converter system, including PWM inverter mode in which energy flows from the battery bank to the three-phase utility-grid in addition to an active PWM converter mode in which energy flows from the utility-grid to the battery banks are described respectively by the control implementation on the basis of d-q coordinate plane transformation. The multifunctional operation characteristics of this three-phase ZVS PWM bi-directional converter with QRDCL is demonstrated fer a BESS under the power conditioning and processing schemes of energy supply mode and energy storage mode, and compared with a conventional three-phase hard switching PWM bi-directional converter for a BESS. The effectiveness of the three-phase ZVS PWM hi-directional converter with QRDCL is proven via the simulation analysis.

• Proceedings of the KIEE Conference
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• summer
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• pp.1504-1506
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• 2004

Photovoltaic and wind power generation have an advantage of unpolluted and unlimited amount of energy resource. Since there is such an advantage in these energies, But photovoltaic system and wind system cannot always generate stable output with ever-changing weather condition. In this paper, the auxiliary power generator for hybrid system(photovoltaic 500[W], wind power generation 400[W]) was suggested. the auxiliary power generator that uses elastic energy of spiral spring to photovoltaic system was also added for present system. when output of photovoltaic system gets lower than 24[V], power was continuously supplied to load through the inverter by charging energy of spiral spring operates in DC generator.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.1
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• pp.66-70
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• 2013

The input current of three phase rectifier which is mainly used in the propulsion system of the electric propulsion ship includes a variety of low order harmonics. To reduce these harmonics, the power conversion system, used in the large vessels which high power is required, is currently used the rectifiers of 12-pulse output, but it still has a problem that occurs $12{\pm}1$ harmonics. Also, in the case of the direct torque control technique which is widely used for the speed and torque control, the torque ripple is severe and the input current of motor has greatly included harmonics by the switching of the inverter. In order to reduce harmonics and improve the performance of torque control, this paper presents that the auxiliary supply assisted into the 12-pulse rectifier of the electric propulsion system using direct torque control technique. We confirm the validity of the proposed method through the simulation under the environment of a real vessel system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7957-7963
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• 2015

R&D trend for Auxiliary Power Supply(APU) of electric vehicle can be well understood by analyzing patents at home and abroad. Based on this trend analysis, domestic technology development direction is proposed. To get technique trend, patents of Korea, Japan, Europe and America published until February of 2014 are analyzed by WIPS DB. First, power converter and transformer two big category are classified. Power converter can be classified into resonant DC to DC converter and resonant Half bridge inverter; transformer can be classified into high frequency transformer, ferrite transformer and matching transformer. By analyzing R&D trend of different counties, companies and years, specific technology needed to be developed and trend of technology can be accurately grasped.