变脉宽脉冲序列控制DCM Buck变换器

摘要

为解决脉冲序列（pulse train，PT）控制开关DC-DC变换器稳态输出电压纹波较大的问题，通过研究较大输出电压纹波的产生机理，提出了一种变脉冲宽度脉冲序列（variable width pulse train，VWPT）控制方法。该方法基于电感电流断续导电模式（discontinuous conduction mode，DCM）Buck变换器，根据负载功率的变化，采用数字控制方式动态调节高、低功率脉冲占空比，得到两个能量差异较小的驱动脉冲，实现对变换器的控制，以获得明显优于PT控制的输出电压纹波特性。实验结果表明，相比于PT控制，VWPT控制可以有效降低变换器的稳态输出电压纹波50％左右。%In order to solve the problem that DC-DC converter switch has a large steady-state output voltage ripple in pulse train (PT)control,a variable width pulse train (VWPT)control method was proposed after analysis of the generating mechanism of large output voltage ripples. The VWPT control method is based on a buck converter operated in discontinuous conduction mode (DCM). According to the load power change,the duty ratios of high and low power pulses can be regulated dynamically by digital control,and then the converter can be controlled by two drive pulses with small energy discrepancy. Thus,the characteristics of output voltage ripple in VWPT control are obviously better than in PT control. The experimental results show that the steady-state output voltage ripple in VWPT control can be reduced about 50% compared with that in PT control.