• 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.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.16-26
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• 2014

This paper proposes new 13-level inverter topology and DC/DC converter buck-boost structure topology for multilevel, compounding uni-directional and bi-directional switches, and proposes high-efficient multilevel inverter system in which the proposed two PCS(Power Conditioning System) was connected in series. In proposed multilevel inverter of forming a output 13-level phase voltage by using total 18 switching parts, Then bi-directional switch has a characteristic of reducing conduction loss and controlling the reactive power effectively by separating electrically from the neutral point. DC/DC converter for supplying in dependent 3 DC voltage to the proposed multi-level inverter generates 180-degree phase shifted PWM by the symmetrically combined structure of 2 buck-boost converter and twice switching frequency efficiency can be obtained, meanwhile, the converter can step up/down the output voltage and 20% output can be generated comparing the input voltage. This proposed system is verified with the simulation and laboratory test.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.543-549
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• 2005

This paper presents a carrier-based modulation method for the control of a matrix converter. By using the offset voltage and changing the slope of the carrier, it is possible to synthesize sinusoidal input currents with unity power factor and the desired output voltages. The proposed method is equivalent to the so called SVPWM (Space Vector PWM) method, but its implementation is much easier. Moreover, the proposed method is very attractive because it is possible to apply the 2 phase t 3 phase modulation method, overmodulation method and other methods which are well-developed in the study of voltage source inverters (VSI) to the matrix coverter modulation. The feasibility of the proposed modulation method has been verified by computer simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1248-1250
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• 2000

The aim of this paper is to present a review of recently used current control technique for three-phase voltage source pulse-width modulated converters. Various technique, different in concept, three current control methods are presented in this paper. Current -control methods to be applied in system are PI controller. Predictive current controller. Minimum-time current controller respectively. In initial state and transient state, the response characteristics of three current control methods are verified through simulations.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.27-36
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• 2007

This paper proposes a current control scheme of the PWM converters under nonideal source voltage conditions such as unbalance and distortion. For the distorted source voltage, the harmonic current controllers are introduced to the conventional current controller. These control loops can eliminate the 5th and 7th order harmonics which are hardly to be done by using filters. For the unbalanced source voltage, a negative sequence current controller is introduced either to reduce the DC-link voltage ripples or to eliminate the source current unbalance. Experimental results show the validity of the proposed control scheme.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1001_1002
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• 2009

본 논문은 태양광 PCS 발전 시스템을 위한 3KW 3상 인터리브드 부스트 컨버터의 동작과 제작을 위한 기반사항에 대해 서술하였으며, 컨버터의 희망 출력전압을 얻기 위한 제어부의 구성과 비례전류제어를 사용한 동작알고리즘을 포함해 실제 PCB 제작을 위해 선정한 부품 및 배치의 구성에 대해 다루었다. 제어부는 아날로그가 아닌 디지털 제어를 채택하여 컨버터 각 부의 센서를 통해 전류, 전압 값을 취득하고, 이를 DSP에서 처리하여, 기준값과 피드백 값과의 오차 보상을 위한 PWM 신호를 생성, 컨버터를 동작시킨다.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.207-208
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• 2015

본 논문은 사각형 파형(Square wave) PWM 방식을 사용한 3상 양방향 그리드 연결 컨버터에서 사용할 수 있는 제어 방법을 제안하였다. 사각형 파형 드라이브 방식은 정현파 파형 방식보다 스위칭 손실이 작은 장점이 있다. 본 논문에서는 먼저 사각형 파형 방식으로 양방향 그리드 컨버터 회로 구성과 스위칭 패턴을 설명하고 입력 전압 동기화할 때 유의 사항을 분석하였다. Psim 시뮬레이션을 통하여 양방향 컨버터 기능의 유효성을 확인하였다.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.77-81
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• 2004

In this paper a novel line interactive UPS (Uninterruptible Power Supply) using the two 4-leg VSCs and AC line reactor is proposed. The 4-leg Voltage Source Converter(VSC) can use the DC link voltage effectively by the 3-D SVPWM method. Hence the DC battery voltage can be reduced by $15\%$ in comparison to that of the conventional line-interactive UPS system. One VSC is in parallel with the AC line reactor of the power source side, and the other is in series with the load. The parallel 4-leg voltage source inverter controls three-phase line voltage independently in order to control the line reactor current indirectly. It eliminates the neutral line current and the active ripple power of the source side using the pqr theory so that unity power factor and the sinusoidal source current can be achieved even though both the source and the load voltages have zero sequence components. The series 4-leg voltage source inverter compensates the line voltage and allows the load voltage to be balanced and harmonic-free. Both of parallel and series 4-leg voltage source inverters always act as independently controllable voltage sources, so that three-phase output voltage shows a seamless transition to the backup mode. The feasibility of the proposed UPS system has been investigated and verified through computer simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.3
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• pp.268-274
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• 1999

The problem of power factor and hmmonics are occurred in convelter system which used to SCRs and diodes as p power semiconductor devices. IGBT power device with selh:ommutation type was solved that problem. maintain the l input line current with sinusoidal wave CUlTent of input power source voltage. It was estimated that improvement of t transient state characteristics with feedfolward compensator added in the diode rectifier with single phase voltage type i inverter was used to simulation load. As a results it was verified that the transient state characteristics with voltage t type PWM convelter control was improved.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.49-54
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• 1997

One of the drawbacks of using diode-bridge rectifiers in the unity interface, is the line-current harmonic distortion caused by the nonlinear nature of the rectifier operation. So, a PWM converter for the power factor correction is analysed for unity power factor as well as low cost design, which enable to meet the limits of international standards.