A novel stability analysis approach based on describing function method using for DC-DC converters

Due to the nonlinearity of the switching process in DC-DC converters, the stability analysis with traditional linear modelling for DC-DC converters are invalid sometimes, especially in the transition interval from stable region to unstable region. In this paper, describing function method is firstly adopted in switching process modelling of DC-DC converters. Further, a new model based on describing function method for switching process is proposed to investigate the stability of the DC-DC converters. A boost converter is taken as an example in this paper, its traditional linear model and the proposed model with describing function method are both established, and the stability analysis based on these two kinds of models are carried out, respectively. Different stability analysis results are obtained according to the two kinds of models for the same boost converter with same circuit parameters and control parameters. According to the simulation and experimental results, it can be concluded that the stability analysis based on the proposed model with describing function method is more accurate and effective in the transition interval from stable region to unstable region, which provide a new stability analysis way for DC-DC converters.