CLLC谐振变换器调频-扩展移相控制研究

Research on PFM-EPS Control of CLLC Resonant Converter

CLLC谐振变换器因其可实现软开关、功率密度高、调压范围大等优点受到广泛关注,但其传统的控制方法存在开关频率变化大、软开关实现范围窄的不足,导致CLLC变换器效率和功率密度的进一步提高受限。针对上述问题,提出一种CLLC变换器的新型调频−扩展移相控制方法,将控制分为两段并给出了分段的边界条件,通过移相控制缩短了开关频率变化范围,通过增加原边和副边桥的移相角增大了软开关范围。基于基波模型分析了变换器的增益模型和软开关临界条件,并基于MATLAB进行多种控制方法下的对比试验,验证了所提控制方法的正确性和有效性。

CLLC resonant converter has been widely concerned because of its advantages such as soft switching,high power density and large output voltage range.However,its traditional control methods have disadvantages such as large switching frequency range and narrow soft switching realization range,which limited the further improvement of efficiency and power density of CLLC converter.To solve these problems,a novel frequency modulation-extended phase shift control method for CLLC converter was proposed.The control range was divided into two sections and boundary conditions are given.The range of frequency modulation was shortened by extended phase shift control,and the range of soft switching was increased by increasing the phase-shifting angle of the primary and secondary side bridges.The gain model and soft-switching critical condition of the converter were analyzed based on the first harmonic model,and the correctness and effectiveness of the proposed control method were verified by the comparative tests under various control methods based on MATLAB.