Influence of Non-Ideal Factors on the Boundary Control of Buck Converters With Curved Switching Surfaces

Abstract

In boundary control for Buck converters, the dynamic behavior characteristics are strongly influenced by some non-ideal factors. This influence is detailedly analyzed in this paper, and some design principles of the switching surface (SS) are proposed accordingly. First, by using the Adomian decomposition method, a general expression which can approximate the theoretically time-optimal SS with different degrees is obtained, and it can be seen as an extension of the existing second-order SSs. Second, the influences of load resistance, the ratio of capacitance and inductance, parasitic parameters, and the truncation order of SS are respectively shown by analyzing the behavior characteristics of the points along the SSs. For a specific SS, it is shown that the light load and low ratio of capacitance and inductance may cause overshoot of output voltage, which should be avoided in practical application. The simulation and experimental results are provided to confirm the correctness of theoretical analyses, which can give some instructions to determine the SS coefficients in the application of boundary control.

Keywords

• Boundary control
• switching surface
• time optimal control (TOC)
• buck converter
• non-ideal factors