In order to analyse the output characteristics

input impedance and system efficiency of series/series(S/S)compensated type wireless power transfer(WPT)system a model is set up based on transformer T-equivalent circuit. Then set the compensating capacitor as a variable to analyze the characteristics of system under the excitation of voltage source and current source

respectively. The conclusions are obtained from analysis. With respect to output

it is current source when input is voltage source and output is voltage source when input is current source under the condition the capacitor compensates for self-induction. But output is voltage source when input is voltage source and output is not voltage or current source when input is current source under the condition the capacitor compensates for leakage inductance. Input impedance is purely resistive when the capacitor compensates for self-induction. And input impedance is partially inductive when the capacitor compensates for leakage inductance. System efficiency is optimal when the capacitor compensates for self-induction. There is a corresponding load able to make the efficiency optimal whatever the compensation. Finally

the conclusions are verified by experiments. This work is supported by National Natural Science Foundation of China(No. 51307173).