断续导通模式Buck变换器跨周期调制离散解析模型

A Discrete-Time Analytic Model of PSM in DCM Buck Converter

脉宽调制模式DC/DC变换器非线性分析经常采用离散模型。该文基于跨周期调制工作模式建立断续导通模式Buck变换器的闭环同步开关映射模型。分析输出电压随负载电阻变化的非线性特性,得到跨周期调制工作模式下系统在较宽负载调整范围内能够保持稳定输出电压,轻负载下跨周期数目增加,输出电压在定常解与周期n解之间变换且呈现无序性,相邻负载跨周期数目具有渐变特性的规律。基于能量守恒定理,建立每个时钟周期的能量迭代关系式,对同步开关映射模型进行定量验证。

The discrete-time model is usually used in nonlinear analysis of pulse width modulation （PWM） DC/DC converters. Based on pulse-skipping modulation （PSM） mode, a s-switching mapping model of closed loop DCM （discontinuous conduction mode） Buck converter is proposed. The nonlinear characteristic is studied when output voltage varies with load changing. We can draw such conclusions in PSM mode that system output keeps stable within wide load range ,the skipped period number increases at light loads, output voltage orderlessly transfers period-1 solution to period-n solution., the skipped period numbers are gradually changed between two adjacency loads. Based on the energy conservation rule, the iterated energy equations in every clock period is also set up and S-switching mapping model is quantitatively verified by these equations.