三相单级全桥PFC电压尖峰机理分析与抑制

Mechanism and suppression of voltage spike in a three-phase single-stage full-bridge PFC

介绍了一种基于全桥结构的三相单级功率因数校正(PFC)变换器,该变换器工作于电感电流断续模式(DCM),电感电流即输入电流的峰值自动跟踪输入电压,可实现功率因数校正.建立了桥臂开关对臂导通时变换器的简化模型,并分析了该阶段变压器原边电压尖峰的产生机理.分析结果表明,由于变压器漏感的存在,变压器原边于桥臂开关对臂导通期间将产生很大的电压尖峰,该电压尖峰大小由变压器原边的漏感、电流与并联电容三个参数决定.最后,结合电路的工作原理,提出了一种变压器原边无源缓冲电路来抑制该电压尖峰.实验结果表明,变压器原边的电压尖峰得到了有效抑制.

A three-phase single-stage power factor correction （PFC） converter based on full-bridge structure is presented, which operates in discontinuous conduction mode （DCM）. The peak of current in inductors （the input current） follows the input voltage automatically, so the PFC function can be achieved. A simplified model of the converter is established when the bridge diagonal-leg switches turn on, and the forming mechanism of voltage spike across the primary side of the transformer is analyzed during this phase. The analysis results show that because of the existing of leakage inductor of transformer, a large voltage spike across the primary side of the transformer is formed when the bridge diagonal-leg switches turn on, and the voltage spike is determined by the leakage inductance, current and capacitance connecting in parallel across the primary side of the transformer. Finally, according to the working principle of circuit, a passive snubber in the primary side of the transformer is presented to suppress the voltage spike. The voltage spike across the primary side of the transformer is suppressed properly, which has been verified through experimental results.