A nonlinear large-signal model for DC-DC converters

Multi-converter systems have been widely used in many applications, such as aircraft, power system on ship, and renewable energy. With the variation of application conditions, the operation point of multi-converter system changes dramatically. The large-signal stability is a key factor for analysis and design of systems. Due to the complexity of power electronic converters, the large-signal modeling of multi-converter system often face high orders or multi-operation-mode problems. In this paper, a Buck converter with averaged current mode control is taken as an example, the characteristics of converter under different operation modes is analyzed. Then, based on averaged model of converter, a nonlinear large-signal model is proposed. This model has a unified mathematical expression under continuous and discontinuous conduction modes, and reduced orders. Finally, the accuracy of proposed model is verified by cycle-by-cycle simulation results and experimental works.