Abstract:
This paper addresses the angular misalignment
problem in Wireless Power Transfer (WPT) systems by a magnetic field (H-field) forming approach using coil antennas. To
power up a planar receiver coil in any orientation, three dimensional (3D) rotating H-field is required. Using the transmitter
coil antennas with amplitude-modulated current excitations, 3D
polarization of H-field is achieved. The power transfer efficiency
depends on the polarization of the H-field and varies with receiver
inclination. This is applicable for a spherically polarized H-field
which is otherwise expected to provide uniform induced voltage
in the receiver in any orientation. To completely mitigate the
misalignment problem, mathematical analysis of H-field forming
is presented followed by optimization of the 3D polarization.
This evolves in understanding the effect of various 3D H-field
polarizations on the induced voltage and results in an optimum
ellipsoidal polarization achieving performance that is invariant
to the receiver orientation. The results are compared for various
3D polarizations and the best performance is shown by the
proposed solution. The analytically obtained results are validated
through simulations and experimental studies. The results thus
obtained proved the potential of the proposed optimized 3D Hfield polarization in WPT systems where a free-orientation of the
receiver is necessary.
