A control strategy of fuel cell/battery hybrid power source for electric vehicle applications

The present work is a novel control algorithm for utilizing a PEM fuel cell as a power main source and batteries as a supplementary source, for hybrid power source in electric vehicle applications. The proposed control, which takes into account the slow dynamics of fuel cell in order to avoid fuel starvation problems of fuel cell system, is evidently simpler than state machines used for hybrid source control. The control strategy lies in using a fuel cell for supplying energy to battery and load at the dc bus. The structure is fuel cell current-, battery current-, and battery state of charge cascade control. To substantiate the proposed principle, a hardware system is realized by analogical circuits for the fuel cell current loop and numerical calculation (dSPACE) for battery current and state of charge loops. Experimental results with small-scale devices — a 500 W PEM fuel cell and 33 Ah, 48 V lead-acid battery bank — show the excellent control principle during motor drive cycle.