三相LCC无线充电系统变频软开关能效优化研究

Study on energy efficiency optimization of the variable frequency soft switch for three-phase LCC wireless charging system

为提高三相LCC无线充电系统的轻载效率,针对该系统推导出复合谐振网络阻抗及其谐振频率、原边线圈和补偿电路、副边线圈和补偿电路的固有阻抗及其谐振频率的计算式,总结了3种谐振频率和开关频率的配合原则以选择开关管的软开关频率范围,使用变频定占空比控制策略归纳软开关频带优化与阻抗匹配方法。仿真结果表明:该电路在频率和负载范围内具有强鲁棒性的自然软开关切换能力,轻载阶段可使用升频方法降低谐振网络的环流。通过1台传输功率3.87 kW的样机验证了该方案的可行性,当负载在100~600Ω调节、传输效率在94.4%~96.3%变化时,与同类三相系统相比,所提出方法的轻载效率提高了约3%。

In order to improve the light-load efficiency of three-phase LCC wireless charging system,this paper deduces the calculation formulas of composite resonant network impedance and its resonance frequency for the system;the calculation formulas of the inherent impedance and the resonance frequency for both the primary coil with its compensation circuit and the secondary coil with its compensation circuit are deduced as well.This paper then summarizes the cooperation principles of these three resonance frequencies and switching frequencies to select the soft switching frequency range of the switching tube.The methods of soft switch band optimization and impedance matching are summarized by using the variable frequency fixed duty ratio control strategy.The simulation analysis shows that the circuit has a natural soft switching ability with strong robustness in frequency and load range,and the up-frequency method can be used to reduce the circulating current of the resonance network in the light load stage.The feasibility of this scheme is verified by a prototype with transmission power of 3.87 kW.When the load is adjusted between 100 and 600Ωand the transmission efficiency varies from 94.4%to 96.3%,the light-load efficiency of the proposed method increases by about 3%compared with the similar three-phase systems.