Decoupling Optimization of the Three-Coil Coupler for IPT System Featuring High Efficiency and Misalignment Tolerance

The efficiency of an inductive power transfer (IPT) system decreases significantly with misalignment. This article proposes a parameter optimization method for the three-coil coupler (TCC) to obtain high system efficiency and misalignment tolerance. The magnetic flux distribution of the TCC is compared with the conventional two-coil coupler, based on which the reason for high misalignment tolerance of the TCC is clarified. To reduce the optimization time, the concepts of primary self-inductance decoupling and mutual inductance decoupling are introduced. An IPT prototype using inductor-capacitor-capacitor/series compensation topology and the optimal TCC was built to verify the validity of the proposed optimization method. The radii of the transmitting and receiving pads of the TCC are 210 and 130 mm, respectively, and the power transfer distance is 100 mm. The system efficiency is 90.106% in aligned case and 85.446% in the most misaligned case (misalignments in X-, Y-, and Z-axis are 75, 100, and 50 mm, respectively). Compared to the output voltage in aligned case, the output voltage in the most misaligned case is only decreased by 39.26%.