Printed Spiral Resonator for Displacement-Tolerant Near-Field Wireless Energy Transfer

Synthesis between the printed spiral coil and the planar interdigital capacitor for near-field wireless energy transfer (WET) is proposed. The proposed amalgamated design is intentionally positioned under several displacements, namely, planar offsets at the z-axis as well as lateral offsets at both the xand y-axes to investigate tolerance capability. This is particularly crucial in practical circumstances, whereby a perfect alignment between primary and secondary resonators is not usually achieved unless with the integration of magnet plates to aid seamless position latching, otherwise complex adaptive matching circuits are needed to compensate for displacements. At a fixed axial transfer distance of 25 mm, the corresponding maximum simulated and measured transfer efficiency is 73.01% and 71.84%, respectively, under perfect alignment. Sustainable power transfer efficiency (PTE) is demonstrated during a 360° planar clockwise rotation with the step size of 45° and the measured variation ratio is 0.02 while the feasibility of preserving PTE until 0.6 quotients of lateral displacement and axial distance is validated when up to 15-mm lateral offsets occur either from x or y reference planes. It can thus be concluded that the printed spiral resonator proposed appears to be a good candidate to rectify planar and lateral displacements featuring simplicity and space-saving robust structure that necessitates only a minimized footprint, thus paving the way for adaptation in WET applications, such as consumer electronics and implanted medical devices.