Inductive Power Transfer Converter With Center-Tapped Pickup Winding

A step-down wireless power transfer converter with center-tapped pickup windings is proposed in this article. The pickup winding is split into two sections and only one is connected to the load. This topology is more suitable for low-voltage level applications, such as consumer electronic products. Like the conventional series-parallel compensation technique, the circuit does not induce high circulation current at the transmitter coil under light load operation. The loosely coupled coils are analyzed with mutual inductance model; in addition, the input impedance and voltage gain are derived. The input impedance is proportional to the load impedance, and the voltage gain is less sensitive to the load variation. The proposed topology performs better than the conventional one at higher load conditions, especially when the coupling is poor. The efficiency of a laboratory circuit reaches 88.8% at best condition and it is higher than 63% ranging from 10- to 100-W load at 10- or 60-mm coil separation.