移相全桥PWM变换器的DCM研究

当输出滤波电感的电流在一个周期内不连续时,移相全桥PWM变换器就工作在电流断续模式(DCM).在该模式下,输出滤波电感两端电压会出现振荡.这种现象不仅会导致次级占空比增加,还会给输出纹波带来不利的影响,在某些应用场合是不允许的.在详细分析该模式下变换器的工作过程和软开关特性的基础上,通过考虑电路各处的分布参数特别是输出滤波电感的寄生参数,很好地解释了振荡现象.利用PSpice仿真研究,总结出电路中各参数,特别是电感寄生参数对谐振过程的影响规律.提出了一种抑制该振荡的方法,最后通过仿真和实验验证了该方法对抑制DCM下电感电压振荡的有效性.

Study on Phase-Shifted Full-Bridge PWM Converter in DCM

Phase-shifted full-bridge PWM converters work in discontinuous current mode (DCM),when the current of out-put filter inductor is discontinuous in one switching period.The oscillation of inductance voltage is found in DCM convert-er,which is not allowed in some applications.The operation principle in this mode is described in detail to research the os-cillation phenomenon.The output filter inductor is equivalent to LCR paralleled resonant circuit by considering its para-sitic parameters.The resonant characters are influenced by parameters'variety.The influence rule is studied by simulation.A useful method to make the oscillation down is proposed at last and is verified by the experimentally results.