Coil-to-Coil Efficiency of ISS-Compensated Inductive Wireless Power Transfer Links Operating with Load-Independent Output Voltage at Fixed Frequency

Series-series compensated inductive wireless power transfer link (SS-IWPTL) may attain specific load independent voltage gain for given coupling coefficient at two certain operating frequencies, residing away from resonance in either inductive or capacitive regions. Consequently, inverter volt-ampere (VA) rating is increased to withstand corresponding reactive power transfer. Inductive region is typically preferred by designers since zero-voltage switching (ZVS) of inverter transistors is inherently attained. It was recently suggested to design the SS-IWPTL for capacitive region operation and add a shunt inductor across AC-side terminals of either inverter or rectifier (attaining the so-called "ISS compensation") to supply reactive power to the resonant network thus minimizing inverter VA rating. This paper derives analytical expressions for coil-to-coil efficiency of ISS-IWPTL for both inverter-side and rectifier-side compensation inductance placement.