New analytical model for the characterisation of printed spiral coils for wireless power transfer

Near field wireless power transfer (WPT) using transcutaneous inductive links has become one of the strong contenders for the powering of cardiac pacemaker, cardioverter defibrillators and neuroprosthetic devices. One scheme to achieve WPT is the use of a pair of printed spiral coils (PSC) acting as a transmitter and receiver. Optimization of the physical configuration of these PSC's is needed for maximum power transfer efficiency and tolerance to angular and lateral misalignment. This paper presents a new analytical model for the calculation of the self- and mutual inductances, AC resistance, and parasitic capacitance to design compact spiral PSC's for WPT applications. The proposed analytical model enables the rapid calculation of the power transfer efficiency (PTE) analysis of a spiral WPT system. A complete optimization model is also implemented in MATLAB. Furthermore, all analytical results have been validated using the 3D electromagnetic (EM) software ANSYS MAXWELL 3D combined with Agilent ADS circuit simulator.