A Family of Hybrid IPT Couplers with High Tolerance to Pad Misalignment

The transfer performance of inductive power transfer (IPT) systems is greatly affected by the inevitable magnetic pad misalignment. Practical IPT converters are expected to operate satisfactorily under considerable pad misalignments. Current design, control and optimization of IPT circuits have achieved limited pad misalignment tolerance. In this paper, a family of hybrid IPT couplers, which combine a conventional bipolar coupler and a simple series-series (SS) topology, are proposed to achieve high tolerance to pad misalignments. The proposed hybrid IPT couplers are applicable to all IPT compensation topologies. In addition, over-current protection is inherently provided in the event of removal of the secondary coil and load. This paper also provides the design principle of this family of hybrid couplers with different coil winding polarities to achieve a given coupling tolerance. Being a universally applicable IPT coupler with high tolerance to pad misalignment, the family of hybrid IPT couplers can be used in any IPT topology. An S-LCC compensation topology is used to illustrate the design of the IPT system with load-independent constant voltage (CV) output under load and coupling variations. Finally, a 3-kW IPT prototype using a hybrid coupler and the S-LCC topology is built to verify the analytical findings.