Considering the problems of distributed power output instability, parameter perturbation and load fluctuations in direct current (DC) microgrids, an improved auto-coupling proportional-integral (ACPI) bus voltage tracking control method with strong anti-interference ability based on a three-phase AC/DC converter is proposed. Firstly, the uncertainty of the internal dynamics and external disturbances of the DC microgrid is defined as a total disturbance, and thus the nonlinear uncertain system is mapped to an unknown linear system. Secondly, a controlled error system under the inverse excitation of the total disturbance is constructed. Based on that, an ACPI controller model based on the improved adaptive speed factor is designed, and it effectively suppresses bus voltage fluctuations and improves the dynamic response speed of the system. Finally, the robust stability and anti-disturbance robustness of the ACPI closed-loop control system are theoretically analyzed, and a simulation model is built for verification. The simulation results of DC bus voltage tracking under different working conditions show that the proposed control method has a fast response speed, strong anti-interference ability for improing stability on DC bus voltage fluctuations.