Integration of excessive electric vehicle (EV) chargers into the low voltage (LV) network may introduce new challenges. Power hardware in the loop (PHIL) simulations can be used for evaluating such systems as it provides a flexible testing platform to study the overall system as well as individual devices. To facilitate a proper PHIL simulation, a precise mathematical model of the PHIL testbed is required. This paper presents a comprehensive small signal model capable of describing the dynamics of a PHIL testbed developed for evaluating grid-connected EV chargers. The PHIL testbed consists of a PHIL-based battery emulator (BE) and a grid emulator (GE) to mimic the DC side battery energy storage system (BESS) and the AC side LV grid behavior, respectively. A mathematical framework is developed to analyze the stability and predict the accuracy of both PHIL-based emulators. The BE in this paper considers a switch-mode power amplifier (PA). Thus, design strategies for its linear controller are also discussed in the context of cascaded DC-DC configuration. An experimental PHIL platform based on a real time simulator (RTS has been used to validate theoretical predictions and confirm developed models. Finally, the validated PHIL test has been employed for analyzing the performance of a commercial EV charger and its interactions with a weak LV network simulated in RSCADTM/EMTDCTM.
I. Jayawardana, C. N. M. Ho and Y. Zhang, "A Comprehensive Study and Validation of a Power-HIL Testbed for Evaluating Grid-Connected EV Chargers," in IEEE Journal of Emerging and Selected Topics in Power Electronics, doi: 10.1109/JESTPE.2021.3093303.
KEYWORDS: Real-time emulation, hardware-in-the-loop, DC-DC power converters, small signal modelling, battery charger