In charging station, the switching of the electric vehicle may cause DC-MG bus voltage oscillation or even instability. The source of inertia is analyzed in this paper, and a virtual DC generator control that can improve the system damping characteristics and inertia effect is proposed to smooth the voltage fluctuation. The small signal model of the Boost circuit under this control is built. The small signal transfer function between the DC voltage and the output current is derived, and the dynamic characteristics of bus voltage are analyzed when the charging station is disturbed. The zero-pole distribution of the second-order simplified model is used to analyze the influence of the control parameters on the dynamic response, which is used to guide the selection of control parameters. Finally, simulation results verify the validity and reliability of the proposed control method. This work is supported by Hunan Key Research and Development Program of China (No. 2018GK2031).