Resonant coupling analysis for a two-coil wireless power transfer system

Inductive or non-radiative wireless power transfer (WPT) is a popular short range power delivery mechanism for transcutaneous biomedical implants. In this work, the relative performance of a two-coil WPT system is analyzed with each of the coils in series or parallel resonance. This analysis helps in choosing the optimum resonance configuration for a given pair of coils that can maximize the efficiency of the WPT system. The analysis described in this work shows that for a given pair of coils at a fixed distance apart and with the transmitter coil driven by a source with significant impedance, choosing parallel resonance configuration at the transmitter and receiver coils can offer up to 20dB and 25dB higher efficiencies respectively when compared to the series configurations. Thus, there is scope for improving the WPT efficiency with a simple rearrangement of the circuit components.