Phase-Shifted Parallel Transformers Tailoring Large-Capacity and Cost-Effective LVAC/HVDC Converters

Large-capacity low-voltage ac (LVac)/high-voltage dc (HVdc) power conversion poses challenges in technical and economic balancing. This article proposes a prototype of phase-shifted parallel transformers (PSPT), tailoring cost-effective diode or thyristor rectifier (DR/TR)-based converters, while achieving filter-free technical capability comparable to modular multilevel converters at over 40% cost-savings. The paralleled topology overcomes the manufacturing and transportation challenges of the monolithic multiwinding phase-shifted transformer in large-capacity LVac/HVdc applications. Harmonic and commutation analyses demonstrate that the inherent properties of PSPT allow for filter-free operation with low total harmonic distortion and high-power factor, promoting the potential for better bulk-reduction and cost-efficiency over classical DR/TR-based converters. Finally, simulations on large-capacity systems and experiments on the physical prototype verify the effectiveness and advancement of the proposed PSPT topology.