Abstract: In order to buffer the impact of fast charging of electric vehicles on the power grid， permanent-magnet synchronous flywheel energy storage system (PMSM-FESS) used in DC fast charging station (DC-FCS) is studied. On the basis of traditional PMSM double closed-loop control， a control strategy with load current compensation and speed feedback is proposed. Firstly， the load mathematical model of DC fast charging station for electric vehicles is established， and its impact characteristic is analyzed. Then the control strategy of FESS is clarified， and a DC fast charging station system with PMSM-FESS is designed. Finally， simulation model of a fast charging station system with FESS is built on Matlab/Simulink software platform. Simulation results shows that FESS can effectively limit the rise slope of the grid output power， compensate for bus voltage sag of the fast charging station；Control strategy proposed in this paper for PMSM-FESS can still exhibit good power buffering performance for grid， even the system is confronted with continuous load on multiple electric vehicles.

Key words: electric vehicles, DC fast charge station, flywheel energy storage system (FESS), load current compensation, rise slope of the grid power, DC bus voltage