In the process of wireless charging for electric vehicles

the constant current(CC)mode must be changed to constant voltage(CV)mode immediately and smoothly in order to ensure the safety of batteries

which always needs wireless communication between the primary side and the secondary side and complex control methods at the primary side. This paper proposed a method automatically and rapidly changed between the CC mode and the CV mode by changing the resonant compensation network at the secondary side without communication and complex control process. Additionally

a method for designing the parameters at the secondary side is proposed to ensure the stability of the battery voltage at the changing moment. By an example of changing from LCC-LCC to LCC-S resonant compensation network

the proposed design methods are analyzed and verified. The experiment results show that the output current and voltage with the change of load are almost constant by using the proposed methods

and the process of changing from the CC mode to the CV mode is stable

which meet the charging requirement of electric vehicle.