Multiple-Harmonic Modeling and Analysis of Single-Inductor Dual-Output Buck DC–DC Converters

Compared with single-input single-output (SISO) dc–dc converters, salient characteristics, such as variable topology sequences and stronger nonlinearity of single-inductor multiple-output (SIMO) dc–dc converters become the major challenges for the modeling and analysis. In this article, a multiple-harmonic model of single-inductor dual-output (SIDO) Buck dc–dc converters is proposed to investigate the multiple-harmonic oscillation phenomenon and analyze the harmonics in different frequency regions. Based on the proposed model, multiple-harmonic oscillation behaviors with the variations of load resistances are revealed, and these harmonics, including low- and high-frequency harmonics, are assessed. Particularly, according to the principle of parity decomposition, the odd and even component distribution of each harmonic is obtained, and a harmonic interaction index is defined to estimate the degree of asymmetric waveform distortion in two adjacent half-waves. Furthermore, eigenvalue analysis is employed to reveal the occurrence mechanism of harmonic oscillation behavior. In addition, the harmonic behavior boundaries of the system in circuit parameter spaces are given to guide the optimal design of the system. Finally, the effectiveness of the above analysis is verified by experimental results.