Control of fuel cell/supercapacitors hybrid power sources

This paper presents a control strategy for employing PEM fuel cell, known as slow dynamic device, as main power source and supercapacitors, known as high dynamic storage elements, as auxiliary power source for DC distributed system. The main point is to regulate the DC bus, and the important constraint is to avoid speedy operation of fuel cell current. Therefore, fuel cell is simply operating in almost steady state conditions in order to ensure a good synchronization between fuel (hydrogen and oxygen) flow and fuel cell current and to lessen mechanical stresses. The proposed control is based, first, on the regulation of the DC bus voltage through the control of the power delivered by the supercapacitors, and second, on the control of the supercapacitor voltage by the operating of the fuel cell. To validate control algorithms, hardware system is realized by analogical current loops and digital voltage loops (dSPACE). Experimental results, with a ZSW PEM 500 W, 12.5 V, 40 A fuel cell and a SAFT 292 F, 30 V, 400 A supercapacitor module for a 42 V DC distributed network, confirm system operations