In this paper

the operating conditions of the Wireless Power Transfer（WPT） system under different loads

coupling coefficients

and frequencies are analyzed. Based on the T-type equivalent circuit and two-port network

the transfer function models of SS

LCL

and LCC resonant networks are obtained. Meanwhile

the transmission properties of 3 kinds of resonant networks are analyzed. The experimental results show that the 3 kinds of resonant networks all possess the characteristics of constant current output.Among them

the LCC network has a monotonically increasing relationship with the change of load and coupling coefficient

which effectively solves the problem of too small transmission power in SS and LCL networks

and suppresses the power overload situation when the system is in a partial resonance or low coupling state. Finally

an LCC WPT experimental prototype based on phase shift full bridge（PSFB） control is built

which can adapt to the wide load variation range and maintain zero phase angle（ZPA） when the inverter is in different phase shift angles

thus the system has a high transmission efficiency.