Energy management and optimization in hybrid systems

Decline in petroleum reserves and increase in global warming encourage to benefit from other sources and seeking new solutions to produce transportation energy requirements. Fuel cell(FC) systems are expected to become an applicable solution for vehicular applications since they use renewable fuel and are environment friendly. However, using only a FC system for vehicle propulsion may not be sufficient to satisfy all the load demands, especially during high power demands. Besides, standalone using of FC system would increase the size and cost of the FC system. In addition, FC systems are not capable of recovering the braking energy that is renewable. Moreover, using FC system alone during high power demand may cause insufficient humidification or flooding problems in fuel cell membrane, which is the most important component of a FC system. To resolve these problems, FC must be used with a proper energy storage unit, which can be charged rapidly and has high power density. Also, a control method will increase system performance and provide energy gain.This thesis deals using FC and an energy storage unit together and providing optimization of system with a control method to obtain best efficiency. For energy storage system, ultracapacitor (UK) system was prefered that has high power density and can be charged rapidly and for the control method, fuzzy logic controller was prefered. The mathematical model and simulation of FC/UK was carried out on computer environment and the optimization of system was executed with fuzzy logic.