A Compact Design for a Switchable Wireless Charger

With the continuous miniaturization of electronic products, the compact structure of wireless power transfer (WPT) is extraordinarily necessary for consumer electronics. In addition, to meet the need in charging, load independent output current (CC) and constant output voltage (CV) are supposed to be taken into consideration since it is regarded as one of the most popular methods for charging batteries. This paper studies a switchable and compact design for a wireless charger. The compensation network can be changed between double LCL topology and LCL-S topology. Configurable CC and CV outputs can be achieved by adopting two switches without utilizing sophisticated control loops or any communication between the transmitter and the receiver. Compared with LCC compensation networks, the proposed special structure can save components under both double LCL and LCL-S conditions. The ferrite cores naturally take the responsibility as magnetic shielding for unwanted couplings in a such compact structure. This special design not only greatly alleviates the cross-coupling phenomenon but surely makes the compensation networks design straightforward as well. Ultimately, the fundamental analysis, the related mathematical derivation, detailed circuit topologies, switchable compensation designs and the experimental platform are all discussed and investigated. The proposed design is also analyzed and validated by experimental tests under different charging conditions.