[Objective] The 46 phase brushless exciter used in the 1 750 MW nuclear power unit, which has the largest single unit capacity in the world, is significantly different from the common odd numbered camera types. Currently, research on ultra large capacity and even-phase brushless exciters is still relatively lagging behind, and there is an urgent need to analyze the operating mechanism of the 46 phase exciter under various working conditions, including normal and fault conditions, in order to provide a basis for subsequent fault protection. Thus, this paper proposes an analysis method for the parallel equivalent model of armature winding based on even-phase toroidal brushless excitation machine. [Methods] Firstly, the actual structure of the armature winding of the 46 phase brushless excitation machine was analyzed in detail, and then the theoretical waveforms of diode current, armature current, and excitation current were obtained. Then, based on the armature reaction magnetic potential, the harmonic characteristics of the stator excitation current during normal operation, single-diode open circuit, single-phase open circuit, and two-phase open circuit were obtained. Finally, the performance of the proposed analytical method was validated by establishing a finite element simulation model consistent with the actual physical machine. [Results] The correctness of the armature winding parallel equivalent model and the harmonic characteristics of stator excitation current under various operating conditions were verified based on the real machine experiments and finite element simulation results of the 46 phase actual unit. [Conclusion] This paper investigates the operational characteristics of even-phase annular brushless excitation systems and the fault signatures associated with various diode open-circuit failures. The study provides a reference for further research on fault diagnosis in high-capacity nuclear power plants multi-phase brushless excitation systems.