Real-Time Simulation of Level 1, Level 2, and Level 3 Electric Vehicle Charging Systems.

A charging system is required to convert ac electricity from the grid to dc electricity to charge an electric vehicle (EV) battery. According to the Society of Automatic Engineers (SAE) standard, EV chargers can be divided into three levels based on power rating: Level 1, Level 2, and Level 3. This paper investigates the circuit topologies and control principles of EV charging systems at each level. Three high-fidelity testbeds of EV charging systems for a 10 kWh battery are designed and implemented in real-time digital simulator RT-Lab. The testbeds include modeling details such as switching of semiconductors. Twenty-five minutes real-time simulation is conducted for each testbed. Detailed dynamic performance of the circuits and the controls at every stage are presented to demonstrate the charging process. All three level EV charging systems employ high-frequency transformer embedded dual active bridge (DAB) dc/dc converter to regulate battery side dc voltage and current. Hence, average model-based linear system analysis is given to configure the parameters of the phase shift control adopted by the DAB dc/dc converter. In addition, power factor control (PFC) that is employed for Level 1 and Level 2 single-phase ac charging systems, three-phase voltage source converter control that is employed for Level 3 three-phase ac charging systems, are all analyzed. The three testbeds, with their detailed circuit parameters and control parameters presented, can be used as reference testbeds for EV grid integration research.