The regenerative braking energy of electric vehicles can be saved by installing a supercapacitor energy storage system (ESS) permanently at substations, the weak spots of a network or on board vehicles. An acceptable tool for investigation of energy processes in the structures containing ESS is the PSIM software due to the switching mode performance of the ESS power converter. The simulation time is inversely proportional to the simulation time step of PSIM, which is limited by the switching frequency of the ESS power converter and cannot be enlarged. Due to a small time step, the simulation time exceeds greatly the simulated time interval, so tens of minutes and even hours are needed to simulate the processes in long time intervals required for vehicle traffic. The authors propose a continuous model of the ESS power converter, which allows enlarging the simulation time step with decreasing significantly the simulation time.