• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 추계학술대회 논문집
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• pp.64-69
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• 2004

This paper deals with an algorithm for controlling ac output voltage of Z-source inverter using Modified SVPWM (abbreviated as MSVPWM). Unlike the conventional space vector pulse width modulation, MSVPWM has one extra shoot-through zero time $T_{sh}$. During shoot-through zero time, both switches in a leg are conducted simultaneously in order to boost inverter output voltage to any desirable value regardless the line voltage. The algorithm to control linearly the capacitor voltage is suggested to improve the performance of Z-source inverter system. The performance of Z-source inverter using above algorithms is demonstrated in simulation results using PSIM. Index terms-Z-source inverter (ZSI), shoot-through time, three-phase carrier-based PWM, space vector PWM (SVPWM), modified space vector PWM (MSVPWM).

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.192-193
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• 2010

본 논문에서는 Quasi Z-source AC/AC converter를 cascade로 연결한 시스템의 출력 전압 특성을 고찰 한다. 제안된 시스템은 Quasi Z-source AC/AC converter의 buck-boost와 boost의 출력특성을 기본으로 하고 있으며, 각각 출력 단이 절연된 단상 Quasi Z-source AC/AC converter 2대가 cascade로 연결된 구조이다. 제안된 시스템의 응용으로는 고전압 대용량의 교류전원 시스템과 고정 주파수의 가변전압과 같은 분야이다. 본 논문에서는 제안된 시스템에 대하여 PSIM 시뮬레이션을 통하여 출력 특성을 고찰하였다.

• 전력전자학회논문지
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• 제26권1호
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• pp.66-73
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• 2021

This study presents a novel four-channel light-emitting diode (LED) current balancing topology using a current-fed hybrid quasi-Z-source converter. With the proposed structure, currents flowing through four LED strings are automatically balanced owing to the charge (amp-sec) balance condition on capacitors. Thus, automatic current balancing of the proposed driver is simple and precise. In addition, the proposed LED driver uses only one active switch and three diodes. The operating principle and characteristics of the proposed four-channel LED driver are analyzed in detail. To verify the operation of the proposed LED driver, a prototype is built and tested with different numbers of LEDs.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.836-842
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• 2005

This paper presents a power supply of railway signal system using a Z-source inverter. The Z-source inverter overcomes the conceptual and theoretical barriers and limitations of the tradition voltage-source inverter and current-source inverter and provides novel power conversion concept. The Z-source inverter is a Buck-Boost inverter that has a wide range of obtainable voltage.

• Journal of Power Electronics
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• 제15권5호
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• pp.1217-1226
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• 2015

In a grid-connected photovoltaic (PV) system, the traditional Z-source inverter uses a low frequency transformer to ensure galvanic isolation between the grid and the PV system. In order to combine the advantages of both Z-source inverters and transformerless PV inverters, this paper presents a modified single-phase transformerless Z-source PV grid-connected inverter and a corresponding PWM strategy to eliminate the ground leakage current. By utilizing two reversed-biased diodes, the path for the leakage current is blocked during the shoot-through state. Meanwhile, by turning off an additional switch, the PV array is decoupled from the grid during the freewheeling state. In this paper, the operation principle, PWM strategy and common-mode (CM) characteristic of the modified transformerless Z-source inverter are illustrated. Furthermore, the influence of the junction capacitances of the power switches is analyzed in detail. The total losses of the main electrical components are evaluated and compared. Finally, a theoretical analysis is presented and corroborated by experimental results from a 1-kW laboratory prototype.

• 전력전자학회논문지
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• 제17권4호
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• pp.306-314
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• 2012

In case of the conventional DC-AC inverter using two DC-DC converters with unipolar output capacitor voltages, for generating the AC output voltage, the output capacitor voltages of its each DC-DC converter must be higher than the DC input voltage. To solve this problem, this paper proposes a single-phase DC-AC inverter using two embedded Z-source converters with bipolar output capacitor voltages. The proposed inverter is composed of two embedded Z-source converters with common DC source and output AC load. The AC output voltage is obtained by the difference of the output capacitor voltages of each converter. Though the output capacitor voltage of converter is relatively low compared to the conventional method, it can be obtained the same AC output voltage. Moreover, by controlling asymmetrically the output capacitor voltage, the AC output voltage of the proposed system is higher than the DC input voltage. To verify the validity of the proposed system, a DSP(TMS320F28335) based single-phase embedded Z-source DC-AC inverter was made and the PSIM simulation was performed under the condition of the DC source 38V. As controlled symmetrically and asymmetrically the output capacitor voltages of each converter, the proposed inverter could produce the AC output voltage with sinusoidal waveform. Particularly, in case of asymmetric control, a higher AC output voltage was obtained. Finally, the efficiency of the proposed system was measured as 95% and 97% respectively in case of symmetric and asymmetric control.

• 전력전자학회논문지
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• 제13권5호
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• pp.369-375
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• 2008

본 논문에서는 Z-소스 인버터를 사용하여 단상 계통 연계형 태양광 시스템을 제어하는 기법을 제시하였다. 인버터 스위칭소자의 전압 스트레스를 고려하여 광전지 출력전압에 대한 계통 연계형 Z-소스 인버터의 동작영역을 분석하였다. 스위칭 손실을 감소시키면서 shoot-through 시간을 효율적으로 제어하는 스위칭 패턴을 사용하였다. 시뮬레이션 및 32-비트 DSP를 사용한 실험을 통하여 계통연계형 Z-소스 인버터의 제어 시스템의 성능을 평가하였다.

• 전력전자학회논문지
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• 제18권4호
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• pp.322-332
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• 2013

Conventional single-phase series quasi Z-source voltage compensator can not compensate for voltage sag less than 50% that frequently occurs in the industrial field. In this study, single-phase series quasi Z-source voltage sag-swell compensator which can compensate the voltage variation of entire range is proposed. The proposed system is composed of two quasi Z-source AC-AC converters connected in series with output terminal stage. Voltage sag less than 50% could be compensated by the intersection switching control of the upper converter duty ratio and of the upper converter duty ratio. Also the compensation voltage and its flowchart for each compensation mode are presented for entire sag-swell region. To confirm the validity of the proposed system, a DSP(DSP28335) controlled experimental system was manufactured. As a result, the proposed system could compensate for the voltage sag/swell of 20% and 60%. Finally, voltage compensation factor and THD(Total Harmonic Distortion) according to voltage variation and load change were measured, and voltage quality shows a good results.

• 조명전기설비학회논문지
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• 제24권9호
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• pp.36-43
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• 2010

This paper proposes a new type of voltage sag-swell compensator based on a Z-source AC-AC converter. The proposed topology employs a pulse width modulation (PWM) Z-source AC-AC converter along with a injection transformer. A safe commutation strategy is used to eliminate voltage spikes on switches without snubber circuit. During a voltage sag or swell, the proposed system controls the adding or missing voltage and maintains the rated voltage of sinusoidal waveform at the terminals of the critical loads. The proposed system is able to compensate 20[%] voltage swell and is also able to compensate 60[%] voltage sag. In order to control and detect the voltage sag and swell, the peak voltage detection method is applied. Also, the operating principles of the proposed system are described, and a circuit analysis is provided. Finally, PSIM simulation and experimental results are presented to verify the proposed concept and theoretical analysis.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.41-42
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• 2014

본 논문에서는 종전의 3상 PWM 정류기의 문제점을 극복하기 위하여 3상 Z-Source PWM 정류기를 제안하였다. 제안된 정류기는 시스템의 간소화, 안정화, 비용상승을 고려하여 상태관측기가 적용된 센서리스 제어 기법을 적용하였다. 3상 Z-Source PWM 정류기는 교류측 전압센서 없이 DC-link단 전압센서와 입력단 전류 센서만을 이용하여 교류측 전압을 추종한다. 제안된 3상 Z-Source PWM 정류기는 PSIM 시뮬레이션을 통하여 검증 하였다.