Analysis and Design of Cubic Magnetic Coupler for High Distance-to-Diameter Ratio IPT Systems

This paper proposes a kind of Cubic Magnetic Coupler (CMC) for Inductive Power Transfer (IPT) system, which has huge application potential in the charging field of moving targets. The CMC can still maintain sufficient coupling coefficient when used for long-distance wireless power transfer, it also has great capability of Misalignment Tolerance (MT). Distance-to-Diameter Ratio (DDR) is defined to eliminate the impact of coil size and make the comparison between different couplers fairer and easier. This paper optimizes the parameters and shape of the CMC. Then, the proposed coupler is compared with several existing couplers employed in long-distance IPT systems. Double-sided LCC compensation topology is chosen to limit the current flowing through the coupling coils. A CMC with an outer size of $180 \times 180 \times 180 mm^{3}$ was made, based on which an IPT prototype was built. The superiorities of the proposed coupler were verified by a series of experiments. When the DDR equals 3, the coupling coefficient of the CMC is 0.00985, and the maximum DC-DC and AC-AC efficiencies are 64.9% and 72.8%, respectively.