单级Boost桥式PFC变换器的Buck启动策略研究

Buck Starting-up Scheme of Single-stage Full-bridge Boost PFC Converters

单级桥式功率因数校正(power factor correction,PFC)AC/DC变换器结构特点,导致启动过程中输入电感中电流较大,容易发生过流,影响系统的可靠性。结合有源钳位单级PFC变换器结构特点,提出一种基于Buck模式的启动策略,通过改变启动过程中开关管的开关时序,有效抑制输入电感过流。该策略具有不增加主电路复杂程度、不改变电路正常工作状态、不影响系统性能等优点。介绍启动过程,建立简化模型,并在此基础上分析启动过程中输入电感电流的变化情况,设计启动占空比,最后进行实验研究。实验结果验证了理论分析的正确性,表明该策略能够有效抑制单级桥式PFC变换器启动过程中输入电感过流。

Because of the special circuit structure of the single-stage full-bridge power factor corrector （PFC）, there is a big current peak in the input inductor when the corrector starting-up, the stability of the corrector has been influenced. A novel Buck soft starting-up scheme was proposed in the active clamped single stage full-bridge PFC converter in this paper, which suppresses the current peak in starting-up. By changing synchronous timing control of power devices, the scheme could solve the problem without increasing the complexity of the circuitry, while maintaining its normal operation and original performance. The process of staring up and the input current were analyzed by using simplified models of the converter, and the constrained conditions of the key parameters were designed. As experimental proved, that the current peak of the staring up is suppressed, and the validity of the theory is proved as well.