• 전력전자학회논문지
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• 제17권1호
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• pp.77-84
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• 2012

This paper describes the process of optimal resonant frequency design with full-bridge series-loaded resonant dc-dc converter in a high efficiency 3.3 kW on-board battery charger application for Electric Vehicles and Plug-in Hybrid Electric Vehicles. The optimal range of resonant frequency and switching frequency used for ZVS are determined by considering trade-off between loss of switching devices and resonant network with size of passive/magnetic devices. In addition, it is defined charging region of battery, the load of on-board charger, as the area of load by deliberating the characteristic of resonant. It is verified the designed frequency band by reflecting the defined area on resonant frequency.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2009년도 Korea Superconductivity Society Meeting 2009
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• pp.5-5
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• 2009

• 전력전자학회논문지
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• 제22권1호
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• pp.27-35
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• 2017

In this study, an integrated 2-in-1 transformer for a low-weight and low-cost light-emitting diode lighting power supply is proposed. In the transformer, a power factor correction (PFC) inductor and an LLC resonant transformer are placed and integrated on a single magnetic core. The amount of mutual interference, represented by the coupling coefficient, between magnetic fluxes generated from each magnetic source is minimized by using the new shape core of an integrated 2-in-1 transformer. The design consideration on critical conduction mode PFC converter and LLC resonant converter using the proposed 2-in-1 integrated transformer is described, and the overall performance of the 150 W LED PSU shown through the experiment.

• Journal of Power Electronics
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• 제18권4호
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• pp.1154-1164
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• 2018

In single-phase magnetically coupled resonant (MCR) wireless power transfer (WPT) systems, the transfer characteristics, including the output power and transfer efficiency, are significantly influenced by the spatial scales of its coils. As a potential alternative, a three-phase MCR WPT system with cylinder-shaped coils that are excited in a voltage-fed manner has been proposed to satisfy the requirements of compact space. This system adopts a phase-shifted angle control scheme to generate a rotating magnetic field and to realize omnidirectional WPT that is immune to spatial scales. The magnetic field model and equivalent circuit models are built to holistically analyze the system characteristics under different angular misalignments. Research results show that the transfer characteristics can be improved by modulating the phase-shifted angle in each phase. Experiments have also been carried out to evaluate the accuracy of the theoretical analysis and to confirm the validity of the system modeling method.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.45-51
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• 2012

In this paper, the wireless power transfer system using the magnetic resonance was designed and the effect of resonant coil radius and load resistance to this system was analyzed by the circuit analysis method. As a result, the calculated transmitted-power is similar to measured one, and the coil size has a small effect to the coupling coefficients in the resonant frequency band. In addition, the fact that the calculated transmitted-power according to the source frequency is similar to measured one confirms that the circuit analysis methode in this paper is valid. The input side transmission efficiency ${\eta}_i$ including only the loss in the power transfer circuit is almost 90[%] with the large coil in the 10[cm] transfer distance, and 65[%] with the small coil in 1[cm]. The source side transmission efficiency ${\eta}_s$ is 30~40[%] at both coil when load resistance below 4.7[${\Omega}$] has been connected. Considering that the maximum ${\eta}_s$ is 50[%], this is valid in the practical applications.

• Journal of electromagnetic engineering and science
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• 제17권2호
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• pp.76-85
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• 2017

We investigate the indirect-fed magnetic resonant wireless power transfer (MR-WPT) system for wireless charging for mobile devices by rearranging the loops and coils. Conventional MR-WPT is difficult to apply to consumer electronic products because of the arrangement of the resonators. In addition, there are restrictions for charging using a wireless technology, which depend on the circumstances of the usage scenarios. For practical applications, we analyzed the transfer efficiency of the MR-WPT system with various combinations and positions of resonators. Three rearranged configurations (Out-Out, Out-In, In-In) have been considered and experimentally investigated using hollow pipe loops and wire copper coils. There were four types of loops and two types of coils; each one had a different diameter and thickness. The results of the measurements show that the trends of the transfer efficiencies for the three configurations were similar. A transfer efficiency of 82.5% was achieved at a 35-cm distance between the 60-cm diameter transmitter (Tx) and receiver (Rx) coils.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.345-351
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• 2018

This paper analyzes a resonant inverter to generate plasma. The resonant inverter consists of a full bridge converter, resonant network and reactor to generate a magnetic field for plasma generation. A plasma load has very distinct characteristics compared to conventional loads. The characteristics of plasma load are analyzed through experimental results. This paper presents the study on the resonant network, which was performed in order to determine how to achieve a constant current gain. Another important contribution of this study is the analysis of drop-out phenomenon observed in plasma loads which is responsible for unpredictable shutdown of the plasma generator that requires stable operation. In addition, the design process for the resonant network of a plasma generator is proposed. The validity of this study is verified through simulations and experimental results.

• 한국전자파학회논문지
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• 제24권3호
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• pp.352-355
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• 2013

본 논문에서는 자기 공명 방식의 무선 전력 전송 시스템을 위한 고출력 가변 공진기를 제안하였다. 공진 코일에는 스파이럴 구조를 사용하였으며, 공진 코일의 양 끝단에 고출력용 가변 트리머 커패시터를 연결하여 주파수 가변이 용이하도록 설계하였다. 3D 시뮬레이션 툴과 등가 회로 모델링 기법을 이용하여 커패시터 용량 변화에 따른 공진 주파수 변화와 전달특성을 예측하였다. 무선 전력 전송 시제품을 제작하여 측정한 결과, 송/수신 코일이 160 mm의 거리로 이격되어 있을 때, 3.0~4.5 MHz 범위의 공진 주파수 가변이 용이하였으며, 50%이상의 전송 효율을 얻을 수 있었다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권1호
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• pp.22-26
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• 2005

This paper proposes the calculation method of magnetic coupling coefficient of the contactless energy transmission system by 3D finite element method with a variation of the secondary core positions. The primary, secondary self and leakage inductances and the capacitances of a resonant circuit are calculated by the finite element analysis results. From these values, the magnetic coupling coefficients are obtained. The secondary voltages and currents according to the secondary core positions are calculated by using the resonant circuit and compared.

• Transactions on Electrical and Electronic Materials
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• 제6권1호
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• pp.6-9
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• 2005

Aging characteristics of 0.2PMN-0.8PZT multilayer ceramic actuators (MCA) has been investigated by applying both triangular wave function for unpoled and unipolar wave for poling. P-E hysteresis loops of the MCA had been distorted after about 90 million cycles running in triangular wave function. Effective electromechanical coupling coefficient was calculated in resonant and anti resonant frequencies. And pseudo-piezoelectric constant $d_{33}$ was also estimated from the strain versus electric field characteristics. The crack growth of MCA was clearly observed along to the boundary between electrode and inactive area. That results were thought due to the internal tensile stress came from both actuation of $d_{33}$ mode and motion of Poisson ratio.