• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.517-520
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• 2004

본 논문에서는 복소 회로 DQ 변환 기법을 활용하여 3상 PW Cuk AC-AC 컨버터에 대한 완전한 정보를 포함하는 등가모델을 제시하고, 이 모델로부터 상태방정식과 같은 컨버터의 동적 특성의 해석적친 표현을 유도하였다. 또, 이러한 동적 동작특성 해석에 대한 결과는 PSIM 시뮬레이션을 통하여 그 타당성을 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.125-128
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• 2006

This paper presents a novel type soft switching PWM power frequency AC-AC converter using bidirectional active switches or single phase utility frequency AC-high frequency AC matrix converter. This converter can directly convert utility frequency AC (UFAC, 50Hz/60Hz) power to high frequency AC (HFAC) power ranging more than 20kHz up to 100kHz. A novel soft switching PWM prototype of high frequency multi-resonant PWM controlled UFAC-HFAC matrix converter using antiparallel one-chip reverse blocking IGBTs manufactured by IXYS corp. is based on the soft switching resonance with asymmetrical duty cycle PWM strategy. This single phase UFAC-HFAC matrix converter has some remarkable features as electrolytic capacitor DC busline linkless topology, unity power factor correction and sine-wave line current shaping, simple configuration with minimum circuit components, high efficiency and downsizing. This series load resonant UFAC-HFAC matrix converter, incorporating bidirectional active power switches is developed and implemented for high efficiency consumer induction heated food cooking appliances in home uses and business-uses. Its operating performances as soft switching operating ranges and high frequency effective power regulation characteristics are illustrated and discussed on the basis of simulation and experimental results.

• 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.

• 대한전기학회논문지
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• 제45권2호
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• pp.216-223
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• 1996

The active power factor control AC/DC converter needs a current loop compensator to obtain better dynamic characteristics and power factor performance, but the optimal design of a current loop compensator is difficult because the AC/DC converter is a nonlinear system having periodically varying poles and zeros. The predictive current control scheme generates a control input using the dynamic equations of the AC/DC converter so that the dynamic of the AC/DC converter is included in the controller and the necessary bandwidth and the gain characteristics of the current control loop are satisfied. And as a result, a compensator becomes unnecessary and the current loop shows the improved current loop characteristics. In this paper, a power factor controller without current loop compensator by adopting a predictive current control scheme is designed and the designed power factor controller is modelled by using a small signal perturbation modelling technique, and simulated to investigate its small signal characteristics. A 200 W power factor control AC/DC converter is built to verify the effectiveness of the proposed power factor controller.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.40-41
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• 2016

The inverter resistance welder requires AC/DC converter of high efficiency because the converter changes a commercial ac power source to low voltage dc power source. Harmonic components that occur in the conversion process of converter decrease system power factor and deal great damage in electric power system. To improve such problems, this paper proposes a high efficiency AC/DC converter for inverter resistance welder. The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit. As a result, the proposed AC/DC converter obtains low switching power loss and high efficiency.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.165-175
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• 2015

Energy storage system has been widely applied in power distribution sectors as well as in renewable energy sources to ensure uninterruptible power supply. This paper presents a model predictive algorithm to control a bidirectional AC-DC converter, which is used in an energy storage system for power transferring between the three-phase AC voltage supply and energy storage devices. This model predictive control (MPC) algorithm utilizes the discrete behavior of the converter and predicts the future variables of the system by defining cost functions for all possible switching states. Subsequently, the switching state that corresponds to the minimum cost function is selected for the next sampling period for firing the switches of the AC-DC converter. The proposed model predictive control scheme of the AC-DC converter allows bidirectional power flow with instantaneous mode change capability and fast dynamic response. The performance of the MPC controlled bidirectional AC-DC converter is simulated with MATLAB/Simulink(R) and further verified with 3.0kW experimental prototypes. Both the simulation and experimental results show that, the AC-DC converter is operated with unity power factor, acceptable THD (3.3% during rectifier mode and 3.5% during inverter mode) level of AC current and very low DC voltage ripple. Moreover, an efficiency comparison is performed between the proposed MPC and conventional VOC-based PWM controller of the bidirectional AC-DC converter which ensures the effectiveness of MPC controller.

• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.235-242
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• 2008

In this paper, a 24-pulse AC-DC converter is designed, modeled, simulated, and developed to feed non-isolated varying loads. The proposed AC-DC converter configuration consists of an auto-transformer based on zigzag connection to overcome current harmonic problems in AC mains. It improves power quality at AC mains and it meets IEEE-519 standard requirements at varying loads. A set of power quality indices on input AC mains and on DC buses for a load fed from 6-pulse and 12-pulse AC-DC converters is also given to compare their performance. It is observed that input current total harmonic distortion(THD) of less than 8% is possible with the proposed topology of AC-DC converter at varying loads.

• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.152-161
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• 2008

This paper deals with a new wave shaping technique for cost effective harmonic mitigation in ac-dc converter feeding Vector Controlled Induction Motor Drives(VCIMD's) for improving power quality at the point of common coupling(PCC). The proposed harmonic mitigator consists of a polygon connected autotransformer based twelve-pulse ac-dc converter and a small rating passive shunt filter tuned for $11^{th}$ harmonic frequency. This ac-dc converter eliminates the most dominant $5^{th},\;7^{th},\;and\;11^{th}$ harmonics and imposes the reduction of other higher order harmonics from the ac main current, thereby improving the power quality at ac mains. The design of autotransformer is carried out for the proposed ac-dc converter to make it suitable for retrofit applications, where presently a 6-pulse ac-dc converter is used. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed ac-dc converter in a wide operating range of the drive. Experimental results obtained on the developed laboratory prototype of the proposed harmonic mitigator are used to validate the model and design of the ac-dc converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.597-600
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• 2004

In this paper, a static var compensator using PWM Cuk AC-AC converter is presented. The PWM Cuk AC-AC converter is modelled by using complex circuit DQ transformation whereby the basic condition to be used as a var compensator is derived and the static characteristic equations such as input current and reactive power is analytically obtained. Finally, the PSIM simulations show the validity of the modelling and analysis.

• 전력전자학회논문지
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• 제16권5호
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• pp.415-429
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• 2011

본 연구에서는 출력이 직렬 연결된 단상 quasi Z-소스 AC-AC 컨버터를 제안하였다. 제안된 시스템은 단상quasi Z-소스 AC-AC 컨버터 2대의 입력 단을 병렬로 연결하고 출력 단을 직렬로 연결한 구조로 되어 있으며, 역상 모드와 동상 모드 별 전류 흐름과 출력전압의 형성 과정을 나타내었다. DSP로 제어되는 실험 시스템을 제작하여 PSIM시뮬레이션 결과와 비교 분석하였다. 그 결과 각 모드별로 듀티 비를 제어하여 원하는 출력 전압을 벅-부스트 할 수 있었다. 컨버터 1대가 단독으로 운전한 경우에 비하여, 각각의 모드에 대하여 부하 저항의 증가에 따른컨버터 효율과 입력 역률을 제안된 방법에 의하여 개선할 수 있었다. 또한 역상 모드의 경우, 일정 부하에서 컨버터의 효율과 입력 역률을 각각 10[%]와 35[%]정도 개선하였으며, 특히 부하 저항이 변동하는 과도상태에서도 일정한 출력 전압을 유지할 수 있었다.