正-反激组合变换器的能量传输模式及输出纹波电压分析

Energy Transmission Modes and Output Ripple Voltage of Forward-Flyback Converter

为给正-反激组合变换器的设计和研制提供理论指导,对其能量传输模式进行深入研究,发现反激部分工作于连续导电模式(CCM)和不连续导电模式(DCM)时分别存在六种和四种能量传输模式,并推导出各工作模式之间的临界电感,分析得出反激部分工作于CCM时对应各能量传输模式的变压器临界电感随电感的减小而增大。推导出各模式的输出纹波电压解析式并进行对比分析,指出反激部分工作于不完全电感供能时,输出纹波电压随变压器电感的增大而减小;而工作于完全电感供能时,却与变压器电感无关,且随电感的减小而减小,此时,仅需较小的输出滤波电容和电感就可满足输出纹波电压指标要求。仿真与实验结果验证了理论分析的正确性。

The energy transmission modes (ETM) of forward-flyback converter were deeply studied to provide theoretical guidance for its design and development. When the flyback part works in continuous conduction mode (CCM) and discontinuous conduction mode (DCM), there are six kinds and four kinds of energy transfer modes of the ETM respectively. The critical inductances among ETMs were obtained, and the critical inductances of transformer in CCM increase with the decrease of inductance. The expression of the output ripple voltage (ORV) in each ETM was deduced. It is pointed out that the ORV decreases with increasing the inductance of transformer when flyback part works in incomplete inductor supplying mode. However, the ORV is independent of the transformer inductance in complete inductor supplying mode and decreases with decreasing inductance. Meanwhile, only a small inductance and capacitance are needed to meet the requirement of ORV. Simulation and experimental results verify the correctness of the theoretical analysis.