Shaped coil-core design for inductive energy collectors

Abstract

Coil design is important for maximizing power density in inductive energy harvesting as well as in inductive power transfer. In this work, we present a study of coil performance, based on simulated flux distributions corresponding to a real aircraft application case. The use of funnel-shaped soft magnetic cores boosts magnetic flux density by flux concentration and allows the use of a smaller diameter coil. This reduces the transducer mass as well as the coil resistance $(R_{COIL})$, thereby increasing the power density. Analysis and simulation shows a fifty-fold power density increase from moderate funneling and another two-fold increase by coil size optimization. Results are compared with experimental measurements presented in [1] which demonstrate a $\mu \mathrm{W} / \mathrm{g}\left(106 \mu \mathrm{W} / \mathrm{cm}^{3}\right)$ power density from alternating environmental magnetic fields in the $10 \mu \mathrm{T} /300$ Hz range.