• Journal of electromagnetic engineering and science
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• 제18권4호
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• pp.221-230
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• 2018

A method to control the power distribution among receivers by the load values in a single-input, multiple-output (SIMO) wireless power transfer (WPT) system is investigated. We first derive the value of loads to maximize total efficiency. Next, a simple, but effective analytical formula of the load condition for the desired power distribution ratio is presented. The derived load solutions are simply given by system figure of merits and desired power ratios. The formula is validated with many numerical examples via electromagnetic simulations. We demonstrate that with the choice of loads from this simple formula, the power can be conveniently and accurately distributed among receivers for most practical requirements in SIMO WPT systems.

• 마이크로전자및패키징학회지
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• 제10권1호
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• pp.13-18
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• 2003

본 논문에서는 파워 아일랜드(power island)에서 발생되는 잡음 전달을 개선하는 방법에 대해서 연구하였다. 일반적으로 파워 아일랜드는 각 파워 버스(power bus)의 구조적 공진에 의해 잡음 전달이 증가하는 단점이 있다. 따라서 본 논문에서는 두 가지의 잡음 전달 개선 방법을 제시하였다. 첫 번째로 잡음원의 위치를 변화시킴으로서 구조적 공진을 억제하였다. 두 번째로 공진이 발생할 경우 잡음 전달을 감소시키기 위해서 EGI(Elevated Ground Island)를 제안하였다. 해석결과, 잡음원의 위치에 따라 파워 버스의 공진을 최소로 감소시켰으며, EGI를 이용하여 잡음 전달을 효과적으로 감소할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.2208-2209
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• 2011

In this paper, the contactless power transfer using inductive power collector in order to apply to the vehicle such as the electric railway vehicle system is suggested and some ideas for power collector design to improve the power transfer performance are presented. This paper was presented for the transfer characteristic of power from input to output by resonance converter.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.173-181
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• 2017

In this paper, the bifurcation criteria for inductive power transfer (IPT) systems is suggested considering the inductive power pad losses. The bifurcation criteria for series-series (SS) and series-parallel (SP) topologies are derived in terms of the main parameters of the IPT system. For deriving precise criteria, power pad resistance is obtained by copper loss calculation and core loss analysis. Utilizing the suggested criteria, possibility of bifurcation occurrence can be predicted in the design process. In order to verify the proposed criteria, 50 W IPT laboratory prototype is fabricated and the feasibilities of the switching frequency and AC load resistance shift to escape from bifurcation are identified.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.54-55
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• 2011

To transfer the power wirelessly, the inverter converted DC power to a high frequency MHz-grade AC power. And the ECR devices for wirelessly transmitting the power are required. In this paper, the spiral-type ECR device and the high frequency inverter were designed. The operating frequency is approximately 1.2MHz. In addition, using a vector network analyzer, the 1.2MHz operating characteristics of the ECR device for wireless power transfer module are analyzed. It is performed and reviewed on validity of wireless power transfer technologies through experiments.

• 대한전기학회논문지:전력기술부문A
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• 제48권2호
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• pp.113-118
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• 1999

In this, sensitivity based approach to estimate BITC(bilateral interchange transfer capacity) considering the real power flow control function of FACTS devices is presented. The real power flow setting of the FACTS devices is adjusted so that it transfers the power flow from the first violation point of transmission capacity to other transmission lines in the power system, thus allowing more power to be transferred from the specified generator bus to the specified load bus. The transfer between the two bus locations is increased from this new operating condition until a violation of transmission capacity limits occurs or until the setting of the FACTS devices can no longer be adjusted. The proposed algorithm is illustrated using examples of small and real life power system.

• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1211-1218
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• 2017

In this paper, performance of rectangular shaped magnetic power pads for inductive power transfer (IPT) system according to ferrite structure is analyzed. In order to evaluate the influences of ferrite structure, six cases of magnetic power pads are proposed. Self-inductance, coupling coefficient, quality factor, and coil to coil efficiency are compared as the displacement increases in the direction of x or y axis. For accurate estimation, finite element method (FEM) simulation is used and loss components of the power pads are numerically calculated and considered. Through the simulation and measured results, effectiveness of protrusive and enveloping ferrite structure is identified.

• KEPCO Journal on Electric Power and Energy
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• 제8권2호
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• pp.97-101
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• 2022

In this study we investigated the gas to solid heat transfer of bubbling fluidized bed bottom ash cooler installed at the Donghae power plant in South Korea. Several different analyses are done through 1-D calculations and 3-D CFD simulation to predict the bottom ash exit temperatures when it exits the ash cooler. Three different cases are set up to have consideration of unburnt carbon in the bottom ash. Sensible heat comparison and heat transfer calculation between the fluidization air and the bottom ash are conducted and 3-D CFD analysis is done on three cases. We have obtained the results that the bottom ash with unburnt carbon is exiting the ash cooler, exceeding the targeted temperature from both 1-D calculation and 3-D CFD simulation.

• 한국전자파학회논문지
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• 제28권1호
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• pp.61-68
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• 2017

본 논문에서는 저주파 대역에서 동작하는 무선전력전송 시스템에서 발생하는 자기장을 저감하기 위한 개선된 자기장 저감 구조를 제안하였다. 제안된 구조는 자성체와 도체로 구성되었으며, 적용된 다양한 설계 파라미터를 최적화하여 전력전송을 위한 자기장의 상쇄효과는 최소화 하면서 시스템 주변으로 누설되는 자기장 상쇄효과는 개선되도록 하였다. 무선전력전송 시스템의 효율과 주변으로 누설되는 자기장 저감 효과를 컴퓨터 시뮬레이션과 측정을 통하여 분석 및 검증을 하였다. 시뮬레이션 분석 결과, 제안된 구조가 적용된 무선전력전송 시스템의 전력전송효율은 약 77 % 수준으로 기존의 전력전송효율과 동등한 수준을 유지하였다. 또한, 고효율을 유지하는 구조들과 비교하여 최대 근접지점에서 누설되는 자기장의 세기를 약 29~37 % 저감할 수 있었다.

• ETRI Journal
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• 제38권5호
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• pp.962-971
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• 2016

A wireless power transfer (WPT) system is generally designed with the optimum source and load impedance in order to achieve the maximum power transfer efficiency (PTE) at a specific coupling coefficient. Empirically or intuitively, however, it is well known that a high PTE can be attained by adjusting either the source or load impedance. In this paper, we estimate the maximum achievable PTE of WPT systems with the given load impedance, and propose the condition of source impedance for the maximum PTE. This condition can be reciprocally applied to the load impedance of a WPT system with the given source impedance. First, we review the transducer power gain of a two-port network as the PTE of the WPT system. Next, we derive two candidate conditions, the critical coupling and the optimum conditions, from the transducer power gain. Finally, we compare the two conditions carefully, and the results therefore indicate that the optimum condition is more suitable for a highly efficient WPT system with a given load impedance.