A power hardware-in-the-loop test bench for emulation of test scenarios and mission profiles for high-power DC charging stations

This paper presents a power hardware-in-the-loop test bench for high-power DC charging stations for battery electric vehicles. The test bench emulates the three-phase grid and the behavior of the electric vehicle battery, creating a dynamic and flexible testing environment. The employed grid emulator allows for reproducible testing of various grid conditions. The introduced grid conditions include the nominal three-phase grid and selected grid faults. The presented grid fault test scenarios of superimposed harmonic content of the grid voltage, voltage sags and short-term supply interruption enable testing of the charging station for resilience to these fault conditions. The significance of these test scenarios for high-power DC chargers is outlined and derived using standards. The reproducible execution of these scenarios allows the characterization and iterative adaption of the DC charging station during development to increase the resilience to these grid faults. The battery emulator enables the emulation of different battery system voltages, cell characteristics and aged batteries simultaneously to the employed AC grid scenarios. Measurements are conducted using the test bench and an industry grade high-power DC charger presenting the impact of the proposed test scenarios on the output charging current. The results show a significant dependency of the charging current ripple on the grid fault event magnitude, proving the significance of suitable testing environments for compliance with standards and for decreasing the susceptibility of the charging process to grid faults.