Non-Cascaded Model-Free Predictive Direct Voltage Control of Three-Phase Vienna Rectifier

With the benefit of simplicity and ease of implement, the cascade structure is commonly adopted in the three-phase Vienna rectifier control system. However, it is difficult to achieve excellent performance due to the bandwidth limitation of the inner and outer control loops. To address this issue, this paper proposes a model-free predictive direct voltage control (MFPDVC) method based on a linear extended state observer (LESO). Firstly, an ultra-local model containing perturbation terms of parameters is constructed to enhance system robustness in case of parameter mismatches. Secondly, an LESO is designed to observe the unknown parts of the ultra-local model and compensate for the system prediction equation. Thirdly, a cost function including voltage, power and neutral point potential is formulated to achieve multi-objective optimal control with a single loop, which breaks the bandwidth limitation of the cascade structure. Finally, the feasibility and validity of the proposed method are verified through experimental comparison.