一种可控励磁电感的LLC变换器的效率优化

Efficiency Optimization of LLC Converter With Controllable Excitation Inductance

对于LLC谐振变换器轻载效率低的问题,提出一种可控励磁电感的半桥LLC(HB-LLC)谐振变换器。该方案在不改变变换器整体拓扑结构的基础上,只在变压器的两侧磁柱缠绕偏置绕组,通过Buck电路控制偏置绕组电流的大小,通过调节磁芯的磁导率,使得励磁电感的感值发生改变,实现对变换器轻载效率的有效提升。对可控电感的磁路和控制方法进行了详细分析,为谐振变换器工作状态提供理论依据。给出了可控电感的控制逻辑,在此基础上对负荷也进行了分区控制,实现了LLC变换器轻载效率的提高。此外,给出了电路主要元件参数设计流程,并设计制作了一台满载1 kW的电源样机,通过仿真和实验共同验证了所提方案的可行性,与传统的LLC电路相比该电路具有更高的轻载效率。

A half-bridge LLC(HB-LLC)resonant converter with controlled excitation inductance is proposed for the problem of low light load efficiency of LLC resonant converters.On the basis of not changing the overall topology of the converter,this scheme only wraps the bias winding on the magnetic columns on both sides of the transformer,and controls the current of the bias winding through Buck circuit,by adjusting the magnetic permeability of the magnetic core,the inductance of the excitation inductance is changed,and the light load efficiency of the converter is effectively improved.The magnetic circuit and control method of controllable inductance are analyzed in detail,which provides theoretical basis for the working state of resonant converter.The control logic of controllable inductance is given,and on this basis,the load is also controlled by zones,which realizes the improvement of light load efficiency of LLC converter.In addition,the design flow of the main component parameters of the circuit is given and a prototype power supply with a full load of 1 kW is designed and built.The feasibility of the proposed scheme has been jointly verified by simulation and experiment and the circuit has a higher light load efficiency compared to a conventional LLC circuit.