一种DC-DC变换器的离散数学模型

当DC-DC变换器工作于大信号运行条件或系统中出现较大振荡时,变换器将呈现电感电流连续和不连续两种运行模式,为了更确切地描述系统特性,建立了基于两种运行模式的DC.DC变换器离散数学模型.分别给出了基本的Boost和Buck变换器每个开关周期中功率开关关断后电感电流持续时间的计算方法,并根据电流持续时间与开关断开时间的关系预测下个工作周期变换器的运行模式,确定模型的系数矩阵.根据与Simulink系统模块运行结果的比较,验证了离散数学模型的正确性.

Discrete Mathematical Model of DC-DC Converter

Both continuous and discontinuous inductor current modes would be exhibited in DC-DC converter when the converter system was operating with large signal condition,or large oscillatory appeared in the system. For describing the characteristics of system accurately,a discrete mathematical model of DC-DC converter was founded which was based on two operation modes. The way calculating the duration time of inductor current in every work cycle was respectively given,when power switches were turned off in Boost and Buck converter. According to the relation between the duration time of inductor current and the turn-off time of power switch,the operation mode of converter in next work cycle was predicted and the coefficient matrixes of model were confirmed. The validity of discrete mathematical model is approved by comparing with the operation results of system module in Simulink.