Research On Constant Output Characteristic Based On LCCC/S Topology For A WPT System Using Battery Charging

Wireless Power Transfer system(WPT)is a technology that uses high frequency alternating magnetic field to transfer electric energy.It has been widely studied for its safety,convenience,flexibility and aesthetics.And gradually introduced into medical equipment,electric vehicles,mobile electronic equipment and other areas of life,Since most of the devices using wireless energy transmission are battery-driven,this paper aims to use wireless charging transmission to charge batteries safely and quickly.Firstly,this paper introduces the working principle of wireless energy transfer system and gives a method to prolong the battery life and improve the charging efficiency: using constant current(CC)and then constant voltage(CV)charging method.Since the equivalent impedance of the battery increases continuously during the charging process,it is difficult to simultaneously achieve load-independent CC and CV charging outputs and a zero phase angle(ZPA)state.Three main types of charging methods for existing WPT systems to achieve CC-CV were summarized by consulting the literature: frequency conversion control,phase shift modulation and DC-DC auxiliary.Frequency conversion control can cause crossover over a wide range of frequency variations,weakening the stability and controllability of the system,phaseshift modulation control is more complicated,DC-DC assistance will bring additional equipment costs and power consumption.In this paper,we analyze the relationship between the input and output characteristics of various resonant modules and CC-CV charging after studying the basic LC resonant module and the combined resonant module.Then the basic resonant modules are combined into a T-type resonant model,after analyzing the T-type resonant module,it is found that it has the property of converting voltage and current sources to each other,a new LCCC/S composite resonant topology is designed using this conversion property,the input and output characteristics of this topology in constant current(CC)and constant voltage(CV)modes are analyzed,the corresponding parameter adjustment method is derived afterwards The topology is designed to achieve the resonant topology at the load.The designed topology can ensure the zero phase angle between the input current and the input voltage while realizing the load-independent CC-CV charging.This topology utilizes a pair of complementary switches to switch between the CC and CV topologies with simple control and only one compensating resonant capacitor for the receiver-side device.Finally,the simulation and physical experiment platforms of 3A constant current output in CC mode and 48 V constant voltage output in CV mode are established.Through comparative analysis,the feasibility and rationality of the proposed LCCC/S compensated Wireless Power Transfer system are verified.