A Comprehensive Study and Validation of a Power-HIL Testbed for Evaluating Grid-Connected EV Chargers
Isuru Jayawardana, Carl Ngai Man Ho, Yi Zhang
Abstract
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 article 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 article 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 RSCAD/EMTDC.