Study On Wireless Power Transmission For Battery Charging

The inductively coupled power transfer technology (ICPT) is a newly innovated way to deliver power, which uses electromagnetic induction principles to achieve power transmission efficiently and safely, which have broad application prospects in the rail transportation, aerospace, robotics, biomedical, environmental protection, household appliances, mining and water occasions.Generally, ICPT is made up of two sub-circuits: high frequency power supply circuit composed of power inverter and circuit which provide power to the load. The theory and technology used in transformer is not available in ICPT. In order to reduce the energy loss and electromagnetic stress on switches, it is necessary to work in the zero-voltage switch or the zero-current switch mode.Basic principles, research status and development trends of ICPT are introduced. Equivalent circuit model described non-contact transformer is illustrated and the impedance reflection effect is also analyzed. Characteristics of full and half bridge converters in series, parallel resonant circuit were analyzed. Critical and stable condition derived from stability analysis on the system.In this thesis, using ICPT technology, wireless charging solution is studied and realized. Charging security enhanced under the applications of ICPT system.The ER core is selected to transfer power and the phase-locked loop control is used to track the resonant frequency of the various resonant tanks in charging processes. Besides, the transform efficiency is improved by the compensative capacitors. The charging circuit using CC charging algorithm is realized by bq2002 fast-charge management ICs. Finally, the contactless charging system is implemented to verify the performance on a 12V/1800mAh NiCd battery. The best coupling efficiency is 80% in charging processes.