Passivation and Passivity-Based Control of DC–DC Converter With Unknown Constant Power Loads

The loads of dc–dc converter (DDC) are mostly constant power loads (CPLs) in dc microgrid. Due to the negative impedance characteristic, CPLs may lead to the nonpassive factor in DDC. Thus, it may result in DDC, not operating reliably at the desired operating point. In this article, a nonlinear controller based on passivity-based stability theory is proposed for the DDC with CPL, which will improve the stability of the converter. Through damping and interconnection injecting, the alternating component passivity-based controller (PBC) is designed to realize the unified control of output voltage and inductor current. It could realize the passivation of alternating component. Furthermore, this controller can solve the problem of traditional PBCs to control inductor current or output voltage only. Moreover, a power observer is adopted, which could fast estimate the variation of the CPL and improve the adaptability of DDC when CPL changes. The proposed controller not only ensures the stability of DDC under large variation of CPL, but also features fast dynamic response with accurate tracking over wide operating range. Finally, the feasibility and effectiveness of the proposed controller are verified by simulation and experimental results.