• Proceedings of the KIPE Conference
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• 2010.11a
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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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.358-366
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• 2014

This paper proposes a quasi Z-source AC-AC converter with the low DC voltage distribution capability operating as a power electronic transformer. The proposed system has configuration that the input terminals of two quasi Z-source AC-AC converters are connected in parallel, also their output terminal are connected in series. Simple control method of duty ratio was proposed for the in phase buck-boost AC voltage mode and the DC output voltage control. DSP based experiment and PSIM simulation were performed. As a result, the PSIM simulation results were same with the measured results. By controlling the duty ratio under the condition of 100 [${\Omega}$] load, quasi Z-source AC-AC converter could buck and boost the AC output voltage in phase with the AC input voltage, and the same time, the constant DC voltage could be output without affecting the AC output characteristics. And, the DC output voltage 48[V] was constantly controlled in dynamic state in case while the load is suddenly changed ($50[\Omega]{\rightarrow}100[\Omega]$). From the above result, we could know that the quasi Z-source AC-AC converter can act as a power electronic transformer with a low DC voltage distribution capability.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.415-429
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• 2011

In this study, a single-phase quasi Z-source AC-AC converters with a series connection of the output terminals is proposed. The proposed system has configuration that the input terminals of two quasi Z-source AC-AC converters are connected in parallel and its output terminals are connected in series. The out of phase mode and in phase mode of the proposed system are presented. To verify the validity of the proposed converter, a DSP controlled hardware was made and PSIM simulation was executed. As a result, controlling the duty ratio of the converter, the desired buck-boost output voltages could be generated. For each modes, as compared with the single converter operation, the proposed converter could enhance the efficiency and input power factor according to different loads. Also, in case of the out of phase mode under the constant load, the efficiency and input power factor of the proposed system are increased 10[%], 35[%] respectively in compared with the single converter. And, the output voltage is constantly controlled in dynamic state in case while the load is suddenly changed.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.435-436
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• 2016

본 논문에서는 3상 Quasi Z-소스 AC/AC 전력변환기를 제안한다. 제안된 전력변환기는 3대의 단상 Quasi Z-소스 AC/AC 컨버터로 구성되어 있으며, 간단한 듀티 비 제어만으로도 동상 및 역상의 벅-부스트 출력 전압의 발생이 가능하다. 제안된 방식은 PSIM 시뮬레이션을 통하여 타당성을 확인하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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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.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.273-274
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• 2013

본 논문에서는 저전압 스마트 배전시스템을 위한 Quasi Z-소스 AC-AC 컨버터를 제안하였다. 제안된 시스템은 Quasi Z-소스 AC-AC 컨버터의 교류 입력 전압에 대하여, 동상의 출력 전압을 부스트 하고, 역상의 출력 전압을 벅-부스트하는 고정 주파수 가변 전압 VVCF(Variable Voltage Constant Frequency)의 출력특성을 가지고 있다. 또한 Quasi Z-소스 AC-AC 컨버터의 shoot-through 스위치 단에 벅-컨버터를 연결하여 Quasi Z-소스 AC-AC 컨버터의 동작과 함께 저압의 직류 전압을 출력 할 수 있다. PSIM 시뮬레이션과 실험에 의하여, 제안된 시스템이 동상 부스트 모드로 동작하는 경우, PI 제어된 벅 컨버터에 의하여 직류 전압을 출력할 수 있음을 확인하였다.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.141-142
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• 2013

본 논문에서는 단일 Quasi Z-소스 AC-AC 컨버터에 의한 4상한 출력 AC전압 제어를 제안하였다. 제안된 듀티비 제어방법을 통하여 한 대의 Quasi Z-소스 AC-AC 컨버터로도 동상의 벅-부스트 모드와 역상의 벅-부스트 모드를 모두 출력하는 4상한 출력 AC전압 제어를 하였다. 한 대의 Quasi Z-소스 AC-AC 컨버터만으로 종전의 듀티비 제어에 의해 동상의 부스트 모드와 역상의 벅-부스트 모드의 출력 전압이 발생되며, 제안한 듀티비 제어에 의해 동상의 벅 모드가 출력되는 4상한 출력 AC전압 제어법을 PSIM시뮬레이션에 의하여 입증하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.4
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• pp.327-334
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• 2010

This paper deals with a single-phase dynamic voltage restorer(DVR) with a quasi Z-source topology. The proposed system based on a single-phase quasi Z-source PWM ac-ac converter which have features such as the input voltage and output voltage are sharing ground, and input current operates in continuous current mode(CCM). For the detection of voltage sag-swell, peak voltage detection method is applied. Also, the circuit principles of the proposed system are described. During the 60% severe voltage sag and 30% voltage 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. Finally, PSIM simulation and experimental results are presented to verify the proposed concept and theoretical analysis.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.400-401
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• 2011

본 논문에서는 단상 Quasi Z-source AC/AC converter 2대의 출력을 직렬로 연결하여 6.6[kV]/60[Hz]의 배전계통의 전압변동을 보상하는 시스템을 제안하였다. 제안된 시스템은 기존의 단상 Quasi Z-source AC/AC converter의 전압변동 보상기가 보상 못 하는 구간, 즉 배전계통에서 많이 발생하는 50[%] 미만의 전압 sag를 보상할 수 있는 장점이 있다. PSIM시뮬레이션에 의하여, 제안된 방법은 정상전압에 대하여 연속적으로 전압변동이 발생하여도 보상할 수 있었다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.199-208
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• 2012

This paper proposes a quasi Z-source DVR(Dynamic Voltage Restorer) system with a series connection of the output terminals, to compensate the voltage variations in the 6.6[kV]/60[Hz] power distribution system. The conventional DVR using one quasi Z-source AC-AC converter has the advantage which it can compensate the voltage variations without the need for the additional energy storage device such as a battery, but it is impossible to compensate for the 50[%] under voltage sags. To solve this problem, a DVR system using two quasi Z-source AC-AC converters with the series connection of the output terminals is proposed. By controlling the duty ratio D in the buck-boost mode, the proposed system can control the compensation voltage. For case verification of the proposed system, PSIM simulation is achieved. As a result, in case that the voltage sags-swells occur 10[%], 20[%], 60[%] in power distribution system, and, in case that the 50[%] under voltage sags-swells continuously occur, all case could compensate by the proposed system. Especially, the compensated voltage THD was examined under the condition of the 10[%]~50[%] voltage sags and the 20[${\Omega}$]~100[${\Omega}$] load changes. The compensated voltage THD was worse for the higher load resistances and more severe voltage sags. Finally, In case of the voltage swells compensation, the compensation factor has approached nearly 1 regardless of the load resistance changes, while the compensation factor of voltage sags was related to the load variations.