• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.376-378
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• 2008

A new family of single-phase Z-source ac-ac converter(SZAC) based on single-phase matrix converter (SPMC) is proposed in this paper. Compared to conventional Z-source ac-ac converter, the proposed SZAC has unique feature: providing a wide range of output ac voltage with buck/boost in-phase (maintaining phase angle) and buck/boost out-of-phase (reversing phase angle) operation. A new commutation strategy is used to eliminate voltage spikes on switches. The operating principle of the proposed SZAC is presented. Analysis and experimental results are also presented.

• 조명전기설비학회논문지
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• 제28권9호
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• pp.60-66
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• 2014

In case of DC railway, value of ESS(Energy Storage System) is already approved. Whereas AC railway system, there are a lot of differences such as system design and operation pattern. Therefore there is doubt about AC ESS usefulness. Especially, regenerative energy can return to the source. So in case of AC 25kV system, it is necessary to consider different operation algorithm compare to DC railway system. In this paper ESS which is installed in AC high-speed railway was introduced. Power consumption pattern of High speed trains were analyzed, proper storage material was reviewed and operation algorithm was suggested. Super capacitor and Battery was used with hybrid type. Super capacitor was used to handle short term energy movement because of its prompt response and battery was used to handle long term energy movement because of its high energy density. Also in case of operation algorithm, phase control method was upgraded compare to voltage magnitude detection method.

• 충청수학회지
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• 제30권4호
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• pp.357-367
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• 2017

In this paper, we introduce the notion of multiplier of AC-algebra and consider the properties of multipliers in AC-algebras. Also, we characterized the fixed set $Fix_d(X)$ by multipliers. Moreover, we prove that M(X), the collection of all multipliers of AC-algebras, form a semigroup under certain binary operation.

• Journal of Power Electronics
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• 제9권5호
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• pp.736-747
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• 2009

A new type of single-phase Z-source AC/AC converter based on a single-phase matrix converter is proposed in this paper. The proposed single-phase Z-source AC/AC converter has unique features; namely that the output voltage can be bucked and in-phase/out-of-phase with the input voltage; that the output voltage can be boosted and in-phase/out-of-phase with the input voltage. The converter employs a safe-commutation strategy to conduct along a continuous current path, which results in the elimination of voltage spikes on switches without the need for a snubber circuit. The operating principles of the proposed single-phase Z-source AC/AC converter are described, and a circuit analysis is provided. To verify the performance of the proposed converter, a laboratory prototype based on a TMS320F2812 DSP was constructed. The simulation and the experimental results verified that the output voltage can be bucked-boosted and in-phase with the input voltage, and that the output voltage can be bucked-boosted and out-of-phase with the input voltage.

• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.243-253
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• 2008

This paper deals with the analysis, design, and implementation of a single phase AC-DC Zeta converter with high frequency transformer isolation and power factor correction(PFC) in two modes of operation, discontinuous current mode of operation(DCM), and continuous current mode of operation(CCM). A Digital Signal Processor(DSP) based implementation is carried out for validation of the Zeta converter developed design in discontinuous mode of operation. A comparison of both modes of operation is presented for a 1kW power rating from the point of view of steady state and dynamic behavior, power quality, simplicity, control technique, device rating, and converter size. The experimental results of a developed prototype of Zeta converter are presented for validation of the developed design. It is observed that CCM is most suitable for higher power applications where it requires some complex control and sensing of the additional variables.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.414-416
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• 2005

In this paper, a new scheme of current programmed control for three phase PWM AC-AC converter is presented. By considering only the magnitude components, a similar scheme in the DC-DC converter can be extended to the three phase PWM AC-AC converter. The proposed current programmed control will be well adopted into various converter topologies though three phase PWM AC-AC boost converter is treated as an example. The converter analysis is carried out by applying the vector DQ transformation to obtain physical insight into the converter operation. Finally, the experiment result shows the validity of the proposed scheme.

• 전력전자학회논문지
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• 제24권6호
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• pp.445-451
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• 2019

An input power estimation method of a three-phase inverter for the high-efficiency operation of AC motors is proposed. Measuring devices, such as DC link voltage and input current sensors, are required to obtain the input power of the inverter. In the proposed method, the input power of the inverter can be estimated without the input current sensor by using the phase current information of the AC motor and the switching pattern of the inverter. The proposed method is more robust to parameter error than conventional method. The validity of the input power estimation method is verified through experiments conducted on a 1 kW permanent-magnet synchronous motor drive system.

• 한국정보통신학회논문지
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• 제16권10호
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• pp.2253-2260
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• 2012

본 논문에서는 H.264/AVC 복호기의 역변환과 역양자화를 위한 효율적인 하드웨어 구조를 제안한다. 기존 역변환 및 역양자화기에서는 AC계수와 DC계수를 복호하는 순서가 다르다. 색차 DC계수와 인트라 $16{\times}16$ 모드에서 휘도 DC계수는 역변환을 수행하고 역양자화를 수행하는 반면에, 휘도 및 색차 AC계수는 역양자화를 수행하고 역변환을 수행하기 때문에 하드웨어로 구현시 제어 복잡도가 증가한다. 제안하는 구조는 DC계수와 AC계수에 관계없이 역양자화를 수행한 후 역변환을 수행하여 제어 복잡도를 감소시키고, 역양자화 연산을 공통 연산기를 사용하여 처리함으로써 계산 복잡도가 감소한다. 기존 역양자화기에는 나눗셈 연산을 포함하고 있어 복호하는 순서를 변경할 경우 오차가 발생하기 때문에 나눗셈 연산을 역변환 후에 수행하여 오차를 방지한다. 또한, 역변환기와 역양자화기를 3단 파이프라인으로 구성하고 수평 IDCT와 수직 IDCT를 병렬로 구현하여 수행 사이클을 감소시켰다. 제안하는 역변환기와 역양자화기의 매크로블록 당 처리되는 사이클 수를 비교 분석한 결과, 기존 구조 대비 45%이상 향상된 결과를 얻었다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권12호
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• pp.609-615
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• 2005

A 30kW electrical power conversion system is developed for a variable speed wind turbine. In the wind energy conversion system(WECS) a synchronous generator with field current excitation converts the mechanical energy into electrical energy. As the voltage and the frequency of the generator output vary according to the wind speed, a 6-bridge diode rectifier and a PWM boost chopper is utilized as an ac-dc converter maintaining the constant dc-link voltage with only single switch control. An input current control algorithm for maximum power generation during the variable speed operation is proposed without any usage of speed sensor. Grid connection type PWM inverter converts dc input power to ac output currents into the grid. The active power to the grid is controlled by q-axis current and the reactive power is controlled by d-axis current with appropriate decoupling. The phase angle of utility voltage is detected using software PLL(Phased Locked Loop) in d-q synchronous reference frame. Experimental results from the test of 30kW prototype wind turbine system show that the generator power can be controlled effectively during the variable speed operation without any speed sensor.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1998년도 춘계종합학술대회
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• pp.371-376
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• 1998

This paper describes an approach to a speed estimation method to remove speed sensor of underwater robot's AC drive systems. AC motors have been widely used in the field of underwater robot's manipulator or propulsion system. Most of these AC motors for underwater use have usually filled oil to compensate the high pressure in deep-sea operation, where a resolver is adopted to feed back the speed of rotor But this kind of speed feedback devices gives rise to some defects arising from their mechanical complexity and numerous signal lines; a resolver needs 6 or 7 signal lines for proper operation. This paper presents a speed estimation method to improve these problems of induction motor, which is adopted as a prototype of AC motor. The proposed speed estimation method is based on the RFO(rotor flux orientation) vector control method of voltage-fed AC drives. Using the controller of voltage-fed AC drives, it is unnecessary to measure the voltage for the estimation of rotor speed, which reduces the effects of measurement error Numerical simulation is carried out to investigate the validity of the method and the effects of rotors resistance variation.