基于磁耦合的CCM PFC无源无损缓冲电路

摘要

提出了一种新型的基于磁耦合的无源无损缓冲电路,该电路能有效抑制主二极管的反向恢复电流,减小开关管开通期间电压和电流的交叠面积,进而提高功率因数校正的效率和减小电磁干扰.缓冲电路中的缓冲电感和电容通过谐振方式进行能量的无损吸收和传递,耦合绕组使得缓冲电感能量复位的条件更容易满足,且缓冲网络并未引入开关管额外的电压应力.详细介绍了缓冲电路的工作原理和关键的无源元件参数设计方法.500 W样机的关键测试波形和效率对比测试结果表明该缓冲电路具有高效率的优点.%A passive lossless snubber based on magnetic coupling is proposed,which restrains the reverse recovery current and reduces the overlapping area of voltage and current during the turning-on period of switch. Therefore, the efficiency of PFC (Power Factor Correction) is enhanced and the EMI(ElectroMagnetic Interference) reduced. The energy is absorbed and transferred through the resonance of snubber inductor and capacitor. The coupled winding makes the energy of snubber inductor easy to be reset and no additional voltage stress is introduced by the snubber to the switch. The operating principle of snubber and the parameters design of key passive components are presented in detail. The experimental waveforms and efficiency comparison tests of 500 W prototype show the high efficiency of the proposed snubber.