PWM Cuk AC-AC 컨버터를 위한 새로운 Commutation 회로

최남섭,김인동,Li Yulong,노의철 전력전자학회 2006 전력전자학회 논문지 Vol.11 No.5

This paper proposes a new commutation circuit for a PWM Cuk AC-AC converter. The proposed commutation circuit utilizes a modified Undeland snubber as a commutation aid. The snubber circuit has some good features such as reduction of voltage/current stress of the main switches and improved efficiency. The experiment results show the adaptability and feasibility of the proposed commutation circuit. 본 논문에서는 PWM Cuk AC-AC 컨버터를 위한 새로운 commutation 회로를 제안한다. 제안된 commutation 회로는 컨버터 전류의 commutation을 위하여 개선된 Undeland 스너버를 이용한다. 개선된 스너버 회로는 주 스위치의 전압/전류 스트레스 저감, 효율 개선과 같은 장점을 갖는다. 본 논문에서는 실험을 통하여 제안된 commutation 회로의 효과와 적용 가능성을 확인하였다.

AWGN 채널환경에서 Direct-Conversion 수신기의 성능분석에 관한 연구

조형래,김철성,박성진 한국정보통신학회 2001 한국정보통신학회논문지 Vol.5 No.4

최근, 상업적인 pcs시스템은 매우 발전되어 있으며, 결국 차세대 이동통신은 멀티미디어 서비스를 제공하는 IMT-2000에 의해 실현될 것이다. 그러므로 , 새로운 형태의 수신 시스템 연구가 활발히 진행되고 있고, 이중하나가 Direct conversion 방식이다 Direct conversion은 차세대 이동통신 시스템에 필요한 저전력, 소형, MMIC, 저가에 적합한 방식이다. 이 시스템을 사용할 경우 DC-offset의 문제가 발생하게 된다. DC-offset은 시스템에서 주파수 합성기의 누설신호에 의해 원하는 신호의 증폭을 억압한다. 본 논문에서 DC-offset을 제거하는 방법에 대해 고려한다. DC-offset의 제거법에는 AC-coupling, 대용량 capacitor, DC-feedback loop, DC-free coding의 4가지 방법이 있다. 이중에서 AC-coupling법은 가장 간단하며, DC-feedback법은 최고의 성능을 가진다. AC-coupling법과 DC-feedback법을 HP사의 ADS를 사용하여 시뮬레이션 하였다. Recently, the performance of the commercial PCS(Personal Communication Service) system has been improved to the uppermost limit and ultimately the next generation mobile communication is to be realized by IMT-2000 (International Mobile Communication-2000) to provide multimedia services. Therefore, the new type receiving system is researched actively and one of the most important part in a receiver is direct conversion method. The direct conversion method is suitable for low power consumption, small size, MMIC, and low price, which is to be adopted to the next generation mobile communication systems. In this case, however, several problems occur due to DC-offset. The DC-offset suppresses amplification of the required signal because of the leakage signal of frequency synthesizer in the system. In this thesis, the removing method of DC-offset was considered. There are four removing techniques of DC-offset, which are AC-coupling, large capacitor, DC-feedback loop, and DC-free coding. Among these, the AC-coupling method is the most simplest method and the DC-feedback loop method has the best performance. Then, the performance of the AC-coupling method and DC-feedback loop method are evaluated by HP's ADS simulation tool. As a result, the AC-coupling method cannot be used to the digital communication systems due to data loss. On the other hand, it was confirmed that the DC-feedback loop method is suitable for the direct conversion receiver.

Design and Implementation of Comprehensive Converter

Sathyaseelan B.,Vijay Shankar S.,Suresh K.,Saravanan R. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.6

This novel Comprehensive Converter (CC) proposes multiple power conversion approach for step-up and step-down processes in AC-DC, DC-DC, AC-AC and DC-AC conversions. This versatile converter is designed by using power electronics switches, for AC-DC & AC-AC conversions thyristors are preferred, whereas DC-DC & DC-AC operations require both turn-On and turn-Off control so transistors (IGBT) is the most suitable switch. Conversion in all the stages can be controlled by a digital controller according to the requirement. All four conversions can perform step-up as well as step-down process, so design of inductor and capacitor values are very much important. All four modes of operations 4 thyristor based transistors and two diode based transistors are used to ensure switching operations. Novelty of the research work is conversion of power in all the modes can be bidirectional and also in single stage process, but in the existing systems of power conversions is an unidirectional process. Proposed single stage power conversion has more effi ciency because of low switching losses. This proposed converter was designed by using mathematical analysis, tested at simulation level and verifi ed in the real time experiment

Survey on the Hexverter Topology – A Modular Multilevel AC/AC Converter

Dennis Karwatzki,Lennart Baruschka,Axel Mertens 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The Hexverter modular multilevel converter topology has been recently proposed for three-phase to three-phase AC/AC conversion. This paper outlines the current state of the art of the Hexverter. The basic working principle is explained and the control concept is introduced. The differences to alternative topologies are discussed and possible applications are pointed out.

Direct High Frequency Soft Switching PWM Cyclo-Converter-Fed AC-DC Converter without DC Link for Consumer Magnetron Drive

Hisayuki Sugimura,Bishwajit Saha,Sang Pil Mun,Eiji Hiraki,Hideki Omori,Mutsuo Nakaoka 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

The oscillation voltage (Ebm) is an important parameter of the characteristic constant of a high power microwave generator. When Ebm could be made high, it serves so as to improve the power conversion efficiency of a magnetron. Thus, the newly developed magnetron with 7% higher oscillation cut-off voltage than the present conventional one is manufactured by Matsushita Electric Industrial Co. Ltd, In addition to this, the utility AC power line current reduced harmonic type direct inverter AC-DC power converter suitable and acceptable for driving this magnetron is proposed in this paper. This direct high frequency inverter type soft switching PWM AC-DC converter has the voltage-boost function based on active clamp scheme with soft switching pulse modulation strategy topology. This paper describes a novel type active clamp AC-DC power converter circuit defined as direct high frequency inverter and the switching operation of this power converter is described and discussed on the basis of simulation and experimental results. The operating characteristics of this soft switching direct high frequency inverter type AC-DC power converter using IGBTs that incorporates the harmonic current improvement as well as power factor correction are evaluated and discussed from a practical point of view as compared with the conventional AC-DC power converter.

소형 풍력발전시스템의 직류전원 적용을 위한 운전제어 및 AC/DC변환 통합장치 개발

홍경진 한국인터넷방송통신학회 2019 한국인터넷방송통신학회 논문지 Vol.19 No.3

In many countries, such as developing countries where electricity is scarce, small wind turbines in the form of Off Grid are an effective solution to solve power supply problems. In some countries, the expansion of power systems and the decline of electricity-intensive areas have led to the use of small wind power in urban road lighting, mobile communications base stations, aquaculture and seawater desalination. With this change, the size of the small wind power industry is expected to have greater potential than large-scale wind power. In the case of small wind power generators, the generator is controlled at a variable speed, and the voltage and current generated by the generator have many harmonic components. To solve this problem, the AC to DC converter to be studied in this paper is a three-phase step-up type converter with a single switch. The inductor current is controlled in discontinuous mode, and has a characteristic of having a unit power factor by eliminating the harmonic of the input current. The proposed converter is composed of LCL filter and three phase rectification boost converter at the input stage and a single phase full bridge for grid connection. It is a control system with energy storage system(ESS) that the system stabilization can be pursued against the electric power. 전기가 부족한 개발도상국 같은 많은 나라에서는 Off Grid 형태의 소형풍력발전이 전력공급 문제를 해결하기위한 효율적인 핵심 솔루션이다. 몇몇 국가에서는 전력계통의 확장과 전기가 부족한 지역의 감소로 소규모 풍력을 도시의 도로 조명, 모바일 통신 기지국, 양식업 및 해수 담수 등의 분야에 이용하기도 한다. 이런 변화에 따라 소형 풍력산업 규모는 대규모 풍력보다 큰 잠재력이 기대되고 있다. 소형 풍력발전의 경우 발전기는 가변 속도로 제어되는 특성이있으며 발전기에서 발생하는 전압 및 전류에는 많은 고조파 성분을 가지고 있다. 이를 해결하기 위해서 본 논문에서는소형 풍력발전시스템의 직류전원 적용을 위한 운전제어 및 AC/DC 변환 통합장치를 제안하며 기존 AC to DC 컨버터는단일 스위치를 갖는 3상 승압형 방식의 컨버터로서 인덕터 전류가 불연속모드로 제어되며, 입력전류의 고조파를 제거하여 단위역률을 갖는 특성을 갖는다. 제안된 컨버터는 입력단에 LCL 필터 및 3상 정류 승압형 컨버터, 계통연계를 위한단상 풀브릿지 형태로 구성되어 있으며 에너지저장시스템(ESS) 기능이 부가된 제어 시스템으로 풍력발전을 이동 평준화방식에 의해 급변하는 전력에 대해 계통 안정화를 추구할 수 있다.

DC-Link Capacitance Minimization in T-Type Three-Level AC/DC/AC PWM Converters

Alemi, Payam,Yoon-Cheul Jeung,Dong-Choon Lee IEEE 2015 IEEE transactions on industrial electronics Vol.62 No.3

<P>In this paper, a novel control algorithm that minimizes the dc-link capacitance in the T-type three-level back-to-back converter is proposed. For this, the charging and discharging currents through the capacitor should be minimized, which can be achieved by utilizing the power balance of the ac/dc converter. Then, the voltage variation in the dc-link is also decreased, which makes a significant reduction in the size of dc-link capacitors. With this scheme, the electrolytic capacitors can be replaced by film capacitors, which are of higher power density, longer lifetime, and higher reliability. The effectiveness of the proposed strategy has been verified by the simulation and experiment results for a 3-kW T-type three-level ac/dc/ac pulsewidth modulation converter system with a 50- μF film capacitor in the dc-link.</P>

Optimal Design of a Damped Input Filter Based on a Genetic Algorithm for an Electrolytic Capacitor-less Converter

Behzad Mirzaeian Dehkordi,Anno Yoo,Seung-Ki Sul 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.3

In this paper an optimal damped input filter is designed based on a Genetic Algorithm (GA) for an electrolytic capacitor-less AC-AC converter. Sufficient passive damping and minimum losses in passive damping elements, minimization of the filter output impedance at the filter cut-off frequency, minimization of the DC-link voltage and input current fluctuations, and minimization of the filter costs are the main objectives in the multi-objective optimization of the input filter. The proposed filter has been validated experimentally using an induction motor drive system employing an electrolytic capacitor-less AC-AC converter.

직접전력변환 방식을 이용한 전압 강하/상승 보상기의 구현

이상회(Sanghoey Lee),차한주(Hanju Cha),한병문(Byung-Moon Han) 대한전기학회 2009 전기학회논문지 Vol.58 No.8

In this paper, a new single phase voltage sag/swell compensator using direct power conversion is proposed. A new compensator consists of input/output filter, series transformer and direct ac-ac converter, which is a single-phase back-to-back PWM converter without dc-link capacitors. Advantages of the proposed compensator include: simple power circuit by eliminating dc link electrolytic capacitors and thereby, improved reliability and increased life time of the entire compensator; simple PWM strategy or compensating voltage sag/swell at the same time and reduced switching losses in the ac-ac converter. Further, the proposed scheme is able to adopt simple switch commutation method without requiring complex four-step commutation method that is commonly employed in the direct power conversion. Simulation and experimental results are shown to demonstrate the advantages of the new compensator and PWM strategy. A 220V, 3kVA single-phase compensator based on the digital signal processor controller is built and tested.

Single-Phase Voltage-Fed Z-Source Matrix Converter

Fang, Xupeng,Liu, Jie Journal of International Conference on Electrical 2012 Journal of international Conference on Electrical Vol.1 No.2

This paper proposes a novel single-phase ac-ac converter topology based on the Z-source concept. The converter provides buck-boost function and plays the role of frequency changer. Compared to the traditional ac-dc-ac converter, it uses fewer devices, realizes direct ac-ac power conversion, and has a simpler circuit structure, so as to have higher efficiency and better circuit characteristics. Compared to the traditional matrix converter, it provides a wider voltage regulation range. The circuit topology, operating principle, control method and simulation results are given in this paper, and the rationality and feasibility is verified.