A Design Methodology of a Free Positioning None- Overlapping Wireless Charging System for Consumer Electronics with a Limited Parameter Variation

Free positioning wireless charging for consumer electronics allows the devices to be charged at arbitrary positions to improve user experience. However, a sudden movement of the device by users during charging can cause hazards due to the abrupt variation of the coupling coefficient. To solve this issue, the variation of the coupling coefficient at different positions should be mitigated. Multiple transmitting coils with overlapping may solve this issue. However, the coil number and the thickness are issues calling for attention. This paper proposes a design methodology of employing antiparallel windings to smooth the variation in a free positioning none-overlapping wireless charging system. Two optimization methods are put forward. Turn-by-turn optimization is to determine the connection of each turn. Winding- by-winding optimization is to group turns into windings and optimize the turn number and direction of each winding. A design flow is offered. Simulations show that the coupling coefficient variation over the entire charging zone can be maintained within a ratio of 1.8 with the average coupling coefficient of 0.1109. Experimental results validate the effectiveness of the methodology.