Optimal Control for Vienna Rectifier in Unbalanced Conditions

The Vienna rectifier is a widely adopted solution for high-power rectification due to its efficiency and straightforward design. However， its performance can degrade under unbalanced three-phase voltage conditions， leading to current zero-crossing distortion and compromised dynamic response. This paper investigates the causes of these distortions， identifying a phase shift between the input current and the grid voltage as a primary factor， and proposes an effective distortion phase identification strategy. Furthermore， the dynamic performance is enhanced through improved current reference calculations and a refined power feedforward strategy. This approach optimizes the system’s response to load changes and maintains output voltage stability under unbalanced conditions. Simulation results validate the effectiveness of the proposed methods in reducing current distortion and improving overall performance.