Maximising inductive power transmission using a novel analytical coil design approach.

Maximising power transfer efficiency (PTE) in resonant inductive power transfer (IPT) systems requires strong coupling between transmitter and receiver coils. In applications where system constraints yield a weak inductive link (e.g. significant distance between coils) or there is a requirement for a specific power level, then geometrically optimising the coils can enhance inductive linkage. To achieve this, a novel coil design method has been presented which provides maximum efficiency for both strongly- and loosely-coupled inductive links. A parameter (i.e. "Strong Coupling Factor") has been introduced to assist the design procedure. Discussing results from a practical 1.06 MHz inductive link - developed using the proposed design method - shows that, with proper selection of strong coupling factor (e.g. C=220), the designed coil geometry can provide maximum PTE of 86%. This is in close correlation (F ≈ 3%) with theoretical analysis using MATLAB

Optimal coil design for maximum power transfer efficiency in resonantly coupled systems.

Maintaining maximum power transfer efficiency (PTE) is one of the main challenges in resonant inductive power transfer (IPT) systems. Maximum PTE can be achieved if the coupling between transmitter and receiver coils is strong. One way of achieving this is to geometrically optimise a coil by employing small ohmic resistance combined with high self-inductance. In this paper a design method for an optimum coil geometry which offers maximum PTE has been introduced. The proposed technique, in addition to minimising the system's physical size, provides high level of PTE for both strongly- and loosely-coupled links. A design example for a typical IPT system is presented that shows, with a proper selection of strong coupling factor (e.g.: C = 220.), the designed coil geometry can provide maximum PTE of 95.4% for coupling coefficient K = 1. Also, for a loose inductive link with K = 0.215, maximum calculated and measured PTE values are 89% and 86%, respectively