A Per-Unit Hardware-in-the-Loop Simulation of a Fuel Cell/Battery Hybrid Energy System

Nowadays, hybrid energy systems have a great applicability for both vehicle and stationary purposes. The design, development, and testing of these systems are not straightforward due to the high number of elements involved, the complexity, and cost. Hardware-in-the-loop (HIL) is an appropriate approach to simulate the hybrid system as it combines both physical and simulated elements. However, the HIL simulation sizing may vary from watts to megawatts, depending on the application. If, instead of carrying out the simulation in absolute values, it is carried out in per-unit (p.u.) values, the HIL test bench will be independent of the application power rating. Hence, a p.u. HIL test bench to simulate a hybrid energy system is proposed. To prove the usefulness and applicability of the HIL simulation presented, a particular fuel-cell hybrid electric vehicle is simulated in real time. Results show that the proposed p.u. HIL simulation is appropriate for the simulation of high-power systems.