无桥Boost PFC变换器变占空比控制方法的研究

摘要

Discontinuous conduction mode (DCM) bridgeless Boost power factor correction (PFC) converter features zero-current turning-on for the switch,zero-current turning-off for the diode and constant frequency operation.Based on the analysis of the operating mode and the derivation of input current and power factor(PF) expression for the DCM bridgeless Boost PFC converter,the PF value decreases sharply as the input voltage increases.To solve the above problems,a variable duty cycle control DCM bridgeless Boost PFC converter is proposed which derives the expressions of instantaneous duty cycle by fitting the duty cycle method.Besides grid current synchronization with grid voltage is realized,the proposed project achieves small output voltage ripple and high efficiency.Simulation and experimental tests have been conducted to demonstrate great performance of the methods above,meeting the operation requirement.%电流断续模式(DCM)无桥Boost型功率因数校正(PFC)变换器具有开关管零电流开通、二极管零电流关断、开关频率固定的优点.通过分析DCM无桥Boost型PFC变换器的工作模态并推导其输入电流与功率因数(PF)的表达式,发现PF值随输入电压的增大而减小.针对该问题,提出了变占空比控制DCM无桥Boost型PFC变换器,采用拟合占空比的方法,推导出瞬时占空比的表达式.该方案实现了网侧电流与网侧电压同频同相,且具有低输出电压纹波与高效率等优点.仿真和实验结果都证明了该方法具有良好的性能,可满足运行要求.