一种双电感结构的LLC谐振型PFCAC-DC变换器

传统的AC-DC电源多采用二极管整流,由于大滤波电容和不控器件的存在,造成电路本身功率因数较低,且会对电网侧产生严重的谐波污染。一般方法多采用再级联一级功率因数校正(PFC)电路,来解决谐波污染和功率因数较低的问题,但由此增加了电路级数,增加了电路结构和控制的复杂度,降低了电路的效率。研究了一种基于双电感结构的具有PFC功能的LLC谐振型AC-DC变换电路,单级电路可以实现高功率因数能量变换,提高了电路传输效率。该电路不仅实现了传统LLC谐振变换,保证开关管以软开关方式工作,而且采用双电感结构的PFC电路,运用并联交错技术,较好地克服了电流断续型PFC电路输入电流谐波畸变较大的问题。对该电路拓扑进行了理论分析和仿真研究,实验验证了该电路拓扑的可行性。

A LLC Resonant AC-DC Converter with PFC Function Based on Double Inductor Structure

The traditional AC-DC power supply usually uses diode rectifier. The existence of the large filter capacitor and uncontrolled device causes low power factor and produces serious harmonic pollution to the power grid side. In order to solve the above problems, a PFC(power factor correction) circuit is cascaded. However, this method in-creases the stage of the circuit, reduces the efficiency of the circuit and makes the structure and control of the circuit complex. In this paper, a LLC resonant AC-DC converter with PFC function based on a double inductor structure circuit is studied to realize the single-stage power conversion and improve the transmission efficiency. The circuit not only can realize the traditional LLC resonant conversion which guarantees switch tubes to work in soft switching mode, but also can overcome the problem of large harmonic distortion of the input current in discontinuous mode PFC circuit, using parallel interleaving technology to the double inductor structure PFC circuit. Theoretical analysis and simulation study are carried out, and the experiments are conducted to verify the feasibility of the circuit.