## 5 Conclusions  
In this paper, a real-time optimization-based energy management strategy by \(\lambda\)_-control_ has been achieved for a fuel cell-battery-supercapacitor-based electric vehicle. A structured method to formulate the optimal control problem and to deduce the model to optimize was first proposed using the energetic macroscopic representation formalism. The performance of the real-time strategy was then assessed by simulation tests for a two-seat urban electric vehicle along a standard driving cycle. The simulation results show that the proposed strategy reduces hydrogen consumption by 7% in comparison with a fuel-cell-based electric vehicle without any secondary source. Moreover, the investigation on the results has confirmed that the SC absorbs the current peaks of the traction, while the battery is used to reduce the dynamics of the fuel cell. To assess the implementation of the strategy in real time, a test rig with a reduced-scale power hardware-in-the-loop (HIL) testing of 1/17 th in power has been also developed. The correlation between simulation and experimentation results has proven that the strategy is fully implementable in real time. Moreover, it has been seen that the strategy is safe by avoiding over-charge and discharge (physical limits) of the secondary energy storages sources. In the future, the robustness of the strategy can be studied under several driving conditions using the same parameters. The temperature effect of the secondary storage energy sources, which can be important, could furthermore be studied on the optimization-based energy management strategy using \(\lambda\)_-control_. Conceptualization, A.C.; Methodology, all authors; Software, A.C.; Validation, A.C.; Formal analysis, A.C.; Writing--original draft preparation, A.C.; Writing--review and editing, all authors; Visualization, A.C. and W.L. ; Supervision, A.B., W.L., and R.T. All authors have read and agreed to the published version of the manuscript. This research received no external funding. The authors declare no conflict of interest. Figure 14: Experimental results: (**a**) DC–DC current of the fuel cell \(i_{d\!\!\!\!\!\! * [PERSON] et al. (2008) [PERSON]; [PERSON]; [PERSON]; [PERSON] Online Energy Management for Hybrid Electric Vehicles. _IEEE Trans. Veh. Technol._**2008**, _57_, 3428-3440. [CrossRef]
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