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Title: A study and the practical implementation of contactless charging platform system
Other Titles: Fei jie chu shi de chong dian ping tai zhi yan jiu yu ying yong
Authors: Chan, Pak Wing (陳栢榮)
Department: Dept. of Electronic Engineering
Degree: Master of Philosophy
Issue Date: 2007
Publisher: City University of Hong Kong
Subjects: Battery chargers
Storage batteries
Notes: CityU Call Number: TK2943.C45 2007
Includes bibliographical references (leaves 83-87)
Thesis (M.Phil.)--City University of Hong Kong, 2007
v, 87 leaves : ill. ; 30 cm.
Type: Thesis
Abstract: This thesis presents a research study on a contactless charging platform system. The proposed system can charge device batteries in the contactless condition, i.e., without any power-cord linking between device and charger. Based on the electromagnetic theory, a power transmitter (the charger) can transmit power to a power receiver (the device module) under the condition of physically electrical isolation. The power receiver can charge a device battery through a device charging IC. This is an extensive study of the Coreless Printed-Circuit-Boards (PCBs) transformer, which can be applied to signal transfer and electrical isolation. In the study, low-power transfer applications (from 0.5W to 5W) are investigated. Studies of design, equivalent-circuit models, characteristics of the charging platform system and the optimum operating condition are going to be discussed. The thesis first presents the operating principle and the driving circuit of the charging platform system. Two designs of the charging platform system are introduced: in system A, the primary winding and the secondary winding have the same planar surface are; in system B, the primary winding area of the charging platform is about 3 times larger than that of the secondary winding area, A novel charging platform that can generate almost even magnetic flux on the surface plane. The equation that shows the magnetic flux distribution is calculated by using the curve-fitting technique and is proved by the experimental measurement. System B is also a multi-load charging system, which means the primary winding can charge two or more secondary loads at the same time. The characteristics of the two charging platform systems are studied independently. In addition, the equivalent circuit models of the charging platform system are studied under different conditions including airgap distances, load resistances and shielding methods. Resonant frequency operation and fixed operation are also introduced. Considering the characteristics of the two operating modes and the applications of the charging platform system, the optimum operating region is suggested to be in inductive mode. An application of the charging platform system is demonstrated: charging batteries of contemporary portable electronic devices. Finally, some suggestions are given for further research.
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