• Journal of electromagnetic engineering and science
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• 제16권4호
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• pp.210-213
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• 2016

This paper presents a wireless power charging system for rechargeable batteries. Recently, misalignment between transmitting coil and receiving coils has been a significant factor to wireless power charging systems, which are prone to lateral and angular misalignment. Unfortunately, the batteries can be easily rolled because of the shape, and coils are often misaligned while charging devices, in practical situations. This paper presents the wireless power battery charging system. In order to solve the angular misalignment, two perpendicular coil having structure of 'plus (+)' shape was proposed. To validate the results, the proposed wireless power charging system was implemented at 6.78 MHz using loosely coupled resonant coils, and the system was verified as being robust to misalignment.

• Journal of Power Electronics
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• 제18권1호
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• pp.309-322
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• 2018

The technology of inductive power transfer has been proved to be a promising solution in many applications especially in electric vehicle (EV) charging systems, due to its features of safety and convenience. However, loosely coupled transformers lead to the system efficiency not coming up to the expectation at the present time. Therefore, at first, the magnetic core losses are calculated with a novel magnetic-circuit model instead of the commonly used finite-element-method (FEM) simulations. The parameters in the model can be obtained with a one-time FEM simulation, which makes the calculation process expeditious. When compared with traditional methods, the model proposed in the paper is much less time-consuming and relatively accurate. These merits have been verified by experimental results. Furthermore, with the proposed loss calculation model, the system is optimized by parameter sweeping, such as the operating frequency and winding turns. Specifically, rather than a predesigned switching frequency, a more efficiency-optimized frequency for the series-parallel (SP) compensation topology is detected and a detailed investigation has been presented accordingly. The optimized system is capable of an efficiency that is greater than 93% at a coil separation distance of 200mm and coil dimensions of $600mm{\times}400mm$.

• 전력전자학회논문지
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• 제21권4호
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• pp.356-363
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• 2016

The design methodology of an adequate input voltage and magnetizing inductance to minimize reactive power is suggested to design a wireless power transfer (WPT) converter for high-power transfer efficiency. To increase the magnetizing inductance, the turn number of the WPT coil is increased, thus causing high parasitic resistance in the WPT coil. Moreover, the high coil resistance produces high conduction loss in the transfer and receive coils. Therefore, the analysis of conduction loss is used in the design of the WPT coil and the operating point of the WPT converter. To verify the proposed design methodology, the mathematical analysis of the conduction loss is presented by experimental results.

• 전력전자학회논문지
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• 제26권6호
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• pp.437-445
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• 2021

This paper proposes an operating frequency design method that limits the voltage applied to aload-side converter during the initial operation of a loosely coupled resonant dual-active bridge (LCR-DAB) converter and an initial operating strategy that applies it. The LCR-DAB converter uses two wireless power transfer coils instead of the high-frequency transformer of the general DAB converter. The wireless power coil has a physical distance of several tens of millimeter or more between the two coils; thus, the LCR-DAB converter is a bidirectional isolated power conversion system that can easily achieve high insulation performance. However, for the initial operation of the LCR-DAB, if the power-side converter is operated at the resonance frequency while the load-side converter is not operating, then a very high voltage due to resonance is applied to the load-side converter, thereby causing damage to the converter. Therefore, a method that can stably charge the DC link voltage of the secondary-side converter during the initial operation is needed. This paper proposes a method to initially charge the secondary-side DC link by operating the primary-side converter at a frequency with limited voltage gain rather than at a steady-state operating frequency. The validity of the proposed frequency design method and initial operating sequence is verified through simulation and experimentation of the 1 KW LCR-DAB converter.

• 조명전기설비학회논문지
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• 제21권3호
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• pp.35-43
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• 2007

본 논문에서는 전자 유도 법칙을 이용한 차량용 유도 전력 집전장치가 제안하였으며 전력 전송 특성을 개선하기 위한 전력 집전체의 몇 가지 설계에 관련된 개점을 제시하였다. 또한 다양한 공진 주파수로 동작되는 직렬 공진 컨버터와 연결하여 전력 전송 시스템의 해석을 나타내었다. 동작 주파수와 파라미터의 변동에 대한 시스템의 민감도가 고려되며, 유도 전력 전송 시스템에 있어서 전력은 코일이나 트랙의 형태인 1차 권선을 통하여 하나, 혹은 그 이상의 절연된 급전 코일로 전송된다. 본 논문은 유도전력전송의 집전장치의 구조를 기존변압기와 유사한 등가회로의 파라미터로 구성하고, 공극 및 권선을 고려한 1차, 2차측 파라미터를 설정하여 1차측 급전 주파수의 변화에 따른 집전특성에 대하여 기술하였다.