• Journal of electromagnetic engineering and science
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• v.18 no.4
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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.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.1
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• pp.13-18
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• 2003

In this paper, we researched on the improved method for transferring noise which is generated from power island. In general case, the power island has a drawback where the noise transfer increase because of the structural resonance in each power bus. Thus, this paper suggests two improved methods that reduces the noise transfer. First method is to suppress the structural resonance by varying the source of the noise. The second method is to utilize the EGI in order to minimize the EGI in order to minimize the transfer of the noise when the resonance occurs. The simulation analysis shows that the relocation of the noise source dramatically minimized the resonance in power bus and the utilization of EGI has effectively reduced the noise transfer.

• Proceedings of the KIEE Conference
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• 2011.07a
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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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• v.12 no.1
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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.

• Proceedings of the KIPE Conference
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• 2011.07a
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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.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.2
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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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• v.12 no.3
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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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• v.8 no.2
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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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.61-68
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• 2017

In this paper, we propose an improved magnetic field shielding structure to reducing the magnetic field generated in the wireless power transfer system operating at a low frequency band. The proposed structure consists of the magnetic material and the conductive material, magnetic field cancelling effect for power transfer is minimized while improving the leakage magnetic field cancelling effect by optimizing the various design parameters in the proposed structure. We analyzed and verified the efficiency of the wireless power transfer system and the reduction effect of the leakage magnetic field through computer simulation and measurement. Analysis results show that power transfer efficiency of the wireless power transfer system utilizing the proposed structure is 77 %, which is maintained at the conventional power transfer efficiency. In addition, compared with the structure maintaining high power transfer efficiency, leakage magnetic field strength is reduced to 29~37 % at the nearest point.

• ETRI Journal
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• v.38 no.5
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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.