Research On Three-phase SEPIC-PFC Cascade LCC-S Wireless Charging Converter

Inductively coupled power transfer(ICPT)system has received widespread attention in the field of wireless charging for electric vehicles because of its good enclosure and safety.Compared with other wireless transmission methods,inductively coupled wireless energy transmission has the characteristics of high transmission efficiency and low loss.In order to realize the high-efficiency work of automobile wireless charging system,this paper studies the wireless energy transmission system of bridgeless three-phase SEPIC and LCC-S compensation network.Three aspects of power factor correction and power control,the characteristics of wireless energy transmission compensation network and the optimal design of loosely coupled transformer are studied.First,it addresses the problem of too many links in a typical wireless transmission system and low transmission efficiency.This paper proposes a new three-phase SEPIC-PFC circuit that integrates rectification,power factor correction and power control into one link to optimize the structure of the wireless charging system.Through a detailed analysis of the intermittent working mode,the characteristics of its automatic power factor correction in the intermittent mode are deduced to simplify the control difficulty and improve the transmission efficiency and reliability.At the same time,according to the working mode of its circuit,the judgment conditions of three-phase SEPIC-PFC current intermittent mode are proposed.Secondly,in view of the problem that the vehicle wireless charging system is prone to lateral offset and leads to parameter changes,this paper adopts the LCC-S wireless energy transmission compensation network,and establishes the T equivalent circuit model and the mutual inductance equivalent circuit model;The power transmission characteristics of series and LCC-S compensation networks are analyzed.In the case of considering the high-frequency current component in the LCC-S compensation network,the conditions for the soft switching of the inverter in the wireless power transmission system are studied;under the consideration of the parasitic parameters,the relationship between the parasitic parameters and the efficiency at different positions is analyzed;The robustness of the LCC-S compensation network to adapt to the change of the coupling coefficient is discussed.Thirdly,this article gives the best design process of various loosely coupled transformers,and the magnetic field and core distribution of the wireless power transmission coil are optimized using the finite element analysis method;the magnetic shielding device of the loosely coupled transformer to ensure human safety is designed and analyzed.The effect of shielding devices on wireless energy transmission network parameters and efficiency.Finally,a charging system experimental prototype of a 3k W three-phase bridgeless SEPIC-PFC converter cascade LCC-S compensation network wireless energy transmission system was designed.Simulation experiments and verifications were carried out to verify the feasibility of this scheme.