Research on Leakage Magnetic Field of Four-Winding Current-Limiting Reactor Under Different Current Excitations

In multi-terminal power supply applications, the leakage magnetic field of current-limiting reactors is complex and difficult to quantify. This paper investigates a power-frequency four-winding current-limiting reactor small model, with the objective of revealing how the magnitude and spatial distribution of winding leakage flux vary under different current excitations. Based on Maxwell’s equations and multi-winding coupling relations, the winding current, core-yoke flux density, axial/radial winding leakage flux density, and leakage magnetic energy are selected as key variables, and a theoretical framework and evaluation indices for leakage-field analysis are established. Using the actual dimensions and material data of the prototype, a three-dimensional finite-element model incorporating the nonlinear B–H curve of the yoke is built in COMSOL, and parameter sweeps are carried out for single-winding excitation and multi-winding coordinated excitation in the 37–168 A current range. The results show that, under single-winding excitation, when the current increases from 37 to 168 A, the maximum leakage flux density around the winding rises from 0.063 to 0.288 T (about 4.6 times), while the maximum flux density in the yoke increases from 0.795 T to about 1.75 T (about 2.2 times). The axial leakage field exhibits a “higher in the middle, lower at the ends” pattern, and the radial leakage is “pronounced at the ends,” both becoming more evident at higher currents. Multi-winding coordinated excitation further reshapes local leakage-flux paths and coupling strength.