Model-Free Power Decoupling Control for Single-Phase Rectifier With Buck Converter

This article proposes a model-free control (MFC) method for a single-phase buck power decoupling ac/dc system. It tackles performance degradation caused by the ripple current coupling between the single phase PWM rectifier (SPR) and the buck decoupling circuit (BDC). The coupling mechanism between both is analyzed through the dc-link ripple current relationship based on the organized mathematical model of system, and a novel ultralocal model (ULM) for the system is established. Next, based on the novel ULM, a model-free predictive current control (MFPCC) strategy for SPR and a model-free power decoupling control (MFPDC) strategy for BDC are designed. Then, an extended sliding mode observer (ESMO) is then designed to estimate the unknown parts of the novel ULM in the two control strategies, compensating for errors induced by dynamic changes of the system. As a result, the proposed method alleviates the impact of converter coupling on system control performance. Finally, the experimental results validate the effectiveness of the proposed approach.