A Matrix-Based Small-Signal Modeling Method for Buck Converters and its Feature Analysis

The power electronic converters are actually single input multiple output (SIMO) systems in frequency domain. Under a perturbation frequency excitation, the state variables contain not only the perturbation frequency but also its sideband components. However, traditional small-signal modeling methods focus on establishing the relationship at perturbation frequency and ignore the other sideband components. The obtained model, therefore, is simplified in a single input single output (SISO) form, which is unsuitable to analyze the interactions of power converters. In this paper, a matrix-based small-signal modeling method is proposed to describe the SIMO characteristics of power electronic converters. Two key conclusions can be obtained from the proposed model: the low frequency component is always the largest and the frequency characteristics are periodical with half switching frequency. Detailed comparison shows that average model and multi-frequency model are all approximations of the proposed model in some special situation. The simulation and experimental results validate the accuracy and effectiveness of the proposed model.