A Novel Communication-Free Carrier Synchronization High-Frequency Circulating Current Suppression Method Based on Reference Prediction for Parallel Power Converters

Parallel power converter system (PCS) have emerged as a promising solution to reconcile the growing demand for high-power applications with the limited capacity of individual converters. However, in paralleled PCS configurations sharing common dc and ac buses, carrier asynchronization (CA) poses a critical challenge to system performance. CA induces periodic fluctuations in zero sequence circulating current (ZSCC) amplitude proportional to carrier phase deviations, thereby degrading system stability and operational efficiency. To this end, a comprehensive ZSCC analytical model is first established to characterize dynamic interactions among parallel converters, which reveals the detailed relation between CA and ZSCC. Then, a novel reference prediction-based communication-free carrier synchronization method based on reference prediction is developed to suppress ZSCC. It shows strong robustness against grid frequency transients and voltage harmonic distortions. The effectiveness and scalability of the proposed method is verified by simulations and experiments.