A new contactless Li-ion battery charging system was proposed. The conventional methods for charging Li-ion battery have some weak points. For example, there can be a contact failure, a poor waterproof, and a difficulty to standardize the battery charging systems. The new proposed system can overcome these weak points.
The new charging system is composed of power transfer part and data transfer part. This paper focuses on the power transfer part for contactless battery charging.
The power stage is mainly composed of PPRC (Push pull Resonant Converter) and flyback converter. The main features of the PPRC topology are : operation under ZVS condition which helps to achieve high efficiency at high switching frequency, sinusoidal voltage waveforms which can reduce the output ripple and the constant transfer ratio independent of the switching frequency and load. So this topology needs another power control stage. Flyback converter can be used for this purpose. The flyback topology can cover the wide input range and can be easily controlled.
The analytical expressions were derived and can be used to develop design guidelines. The proposed topology was tested under the constant voltage control and the constant current control which are adequate for charging Li-ion battery.
