  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.
