Fuel cell characteristic observation to control an electrical multi-source/multi-load hybrid system

This paper deals with flatness based control of a multi-source/multi-load electrical hybrid system (EHS) composed of a fuel cell and a supercapacitor (SC) as the main and auxiliary source, respectively. The proposed method does not contain any commutation algorithm whereas the different operating modes (normal mode and overload mode) exist in the system. This DC-power source supplies two independent 5 V and 12 V loads which are connected to a DC link through the buck converters. An observer system based on monitoring the supercapacitor voltage is also designed and proposed to estimate the output V-I characteristic of fuel cell which varies with some physical and environmental parameters like temperature, humidity, etc. Experimental results prove validity of the proposed approach.