[Objective] To address the limitations of traditional large-scale permanent magnet synchronous wind generators, which cannot regulate the excitation magnetic field, and traditional double-fed generators, which are not suitable for direct drive and require post-installation maintenance, a modular dual-rotor synchronous wind generator is proposed. [Method] The stator winding of the generator was designed using fractional slot concentrated winding (FSCW), while both rotor windings were concentrated and excited by direct current. The stator excitation generated two dominant poles, which magnetically coupled with the dominant poles of the two rotors, forming a flux linkage. First, the basic structure and operating principle of the generator were introduced. Following this, a mathematical model was developed and the electromagnetic characteristics, including flux linkage and induced electromotive force, were analyzed based on FSCW theory. Finally, a finite element simulation model was created, and the simulation results were compared with the theoretical predictions. [Results] The results indicated that flux linkage calculations were accurate when the magnetic surfaces of the stator and rotor teeth were aligned. However, when the teeth were misaligned, the presence of air-gap leakage inductance introduced a certain degree of error in the calculations. [Conclusion] The simulation results are generally consistent with the theoretical calculations, validating the accuracy of the proposed modular dual-rotor synchronous wind generator design.