Design of Free-Positioning Wireless Power Charging System for AAA Rechargeable Battery

This paper presents a free-positioning wireless power charging (WPC) system for AAA Type rechargeable battery. In recent years, misalignment between transmitting coil and receiving coil is very big issue in this area, because efficiency of WPC systems is vulnerable to lateral misalignment and angular misalignment. Unfortunately, the coils could be often misaligned while charging devices, in practical situations. Therefore, this paper proposed the free-positioning WPC system. In order to solve the lateral misalignment, proposed transmitting coil has the uniform magnetic field by changing current distribution. In receiving side, two perpendicular coil having structure of 'plus' (+) shape is proposed to solve the angular misalignment. For validation, the proposed wireless power charging system was implemented at 6.78MHz using loosely coupled resonant coils, and we verified that the proposed system is robust to misalignment.