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The purpose of this paper is to develop a robust hydrogen flow rate control of a proton exchange membrane (PEM) electrolyzer. In this work, a quadratic DC-DC step-down converter is used to interface the DC grid and the PEM electrolyzer since it has an improved voltage ratio compared to the basic step-down converter. The hydrogen flow rate is controlled through the current at the output of the quadratic DC-DC converter. Besides, the hydrogen flow rate strongly depends on the state of charge of hydrogen storage and hydrogen consumption from the fuel cell and consequently, its reference may change during operation. For this reason, to cope with the change of hydrogen flow rate reference, a sliding mode control has been developed. Hence, the controller can ensure good performance when sudden load variations appear. An experimental test bench has been developed with a PEM electrolyzer emulator and the obtained results demonstrate the effectiveness of the developed control strategy.

This paper presents an original model-based control for dc microgrid supplied by a battery bank (main source) and supercapacitor (secondary source) for electric vehicle (e-Vehicle) applications. A nonlinear control approach based on the differential flatness theory is proposed. Utilizing the differential flatness characteristics, we advance simple solutions to hybrid convergence problems and energy management. To corroborate the proposed method, a hardware system is realized with fully digital estimation accomplished with a dSPACE MicroLabBox controller. Experimental results with small-scale devices (a battery bank of 120 V, 40 Ah and a supercapacitor bank of 160 V, 6 F) in a laboratory substantiate the good control scheme during a load-drive cycles.

Fundamentally, a fuel cell (FC) power source is connected with a power switching dc/dc converter. This type of network is a nonlinear manner. A linearized approach is frequently employed to investigate the convergence issue and to set the regulation parameters. In this document, a model-free control (MFC) theory based on the ultra-local model is studied to control the FC power for dc microgrid applications. A proposed parallel 2-phase boost converter with interleaving algorithm is selected to step-up a low output dc voltage of fuel cell to a utilized dc grid level. Using the MFC approach, we put forward simple solutions to nonlinear control problems in power electronics domain. To corroborate the proposed scheme, a dc/dc power converter (2.5-kW two-modules in parallel) is implemented in the laboratory. The studied control law based on the MFC characteristic is realized by fully digital calculation in a dSPACE MicroLabBox platform. Simulation and experimental results with a FC (2.5 kW, 50 V) with hydrogen supplied by a reformer reactor of in the laboratory substantiate the exceptional control scheme.