7m-off-long-distance extremely loosely coupled inductive power transfer systems using dipole coils

An extremely loosely coupled inductive power transfer system (IPTS) for 7m-off-long-distance wireless power transfer using dipole coils is proposed. The superiority of dipole coils for a-long-distance power delivery over loop coils with same configuration of square core, in general, is verified by comparing magnetizing inductance between primary and secondary coils. Series-parallel resonant circuits are used to achieve higher load voltage than the series-series scheme. Contrary to conventional IPTSs or coupled magnetic resonance systems, quality factor Q is set as low as 100, which is, moreover, fixed for guaranteeing frequency tolerance. An optimum number of turns of the secondary coil is derived theoretically and verified by experiments, where a prototype of narrow dipole coils with 2m-length were used to deliver 11.1 W power up to 7m-distance at a very low frequency of 20 kHz.