Study on Suppression of Tank Eddy Current Loss by Phase Angle Difference Adjustment on Low-Voltage Outlet Side of Rectifier Transformer

Research was conducted on the issue of excessive eddy current losses and localized overheating in the tank walls of large-capacity rectifier transformers, such as 27000 kVA units, under high-harmonic and high-current operating conditions. Traditional 12-pulse rectifier systems employ a Y/Δ 30° phase angle difference connection on the valve-side windings, which can lead to "aligned superposition" of leakage fluxes from the two sets of windings, intensifying the magnetic field component perpendicular to the tank wall and exacerbating eddy current losses. To address this, a solution was proposed to optimize the Y/Δ winding phase angle difference to 150°, leveraging the vector cancellation effect of leakage fluxes to reduce the combined leakage flux intensity. A three-dimensional finite element model incorporating low-voltage busbars, insulation layers, and tank walls was established, with comparative analyses of electromagnetic characteristics under 30° and 150° phase angle differences. Simulation results showed that the total eddy current loss decreased from 208143.82 W to 18436.87 W, a reduction exceeding 90%. This study validates the effectiveness of the 150° phase angle difference scheme, providing theoretical support for electromagnetic optimization and heat dissipation design in rectifier transformers.