Development of a Fuel Cell/Ultracapacitor Hybrid Power System

This research aims at the development of a vehicular Hybrid Power Source (HPS) with fuel cell and ultracapacitors. The HPS features high energy density and high power density, and may retrieve regenerative current effectively. The architecture of the HPS contains the fuel-cell, the ultracapacitor, the Energy Management System (EMS), the DC-DC converter system, and the motor load. The DC-DC converter system implements a Backstepping-Sliding-Mode (BSM) control strategy in order to deal with the time-varying, nonlinear environment. The EMS tries to split power between the fuel cell and the ultracapacitor. The aim is that the fuel cell would not be over loaded, and the ultracapacitor would hold appropriate state-of-charge capable of supplying urgent power demand and retrieving regenerative current. Much research effort has been paid to developing the DC-DC converter system due to it confronting a complicated time-varying, nonlinear environment. Eventually, the BSM control strategy was discovered to be efficacious. Simulation tests show that the BSM control strategy in the DC-DC converter system outperforms that uses the voltage- and current-mode control. An experimental HPS with fuel cell and ultracapacitors is implemented. The functions of the BMS and the BSM control strategy are investigated on the experimental HPS. The results show that the proposed design is efficacious.