The advanced control and its experiments of a hybrid PEMFC and ultra-capacitor system

This paper presents the advanced control strategy and experimental study of a clean hybrid power system combining proton exchange membrane fuel cell (PEMFC), as the main power source, and ultra-capacitor (UC), as the energy storage unit. PEMFC is highly efficient energy conversion device that can operate continuously as long as fuel is available. They are environmentally benign and a reliable power source for variant applications. They provide high energy density, and can withstand harsh conditions of high temperature and humidity. One major obstacle towards the adoption of PEMFC as the power source is that the fuel cell´s transient character could not be able to match the demands of the load rapid changing. To meet the requirements, most of the topologic of the fuel cell electric vehicles (EV) adopt hybridization of fuel cell with bridge power, i.e., battery or ultra-capacitor (UC) or the combination of both, and power conditioning unit (PCU). But for the light duty EVs, such as scooters, and light duty vehicles, the PCU would consume energy that could degrade the system efficiency. Unlike the conventional fuel cell hybrid system with PUC, this study investigated the electrical characteristic of PEMFC and UC hybrid system without DC/DC converter, and simulated the fuzzy control logic for the hybrid system. As a platform to evaluate the proposed system, the fuel cell based EV is implemented. The road test showed that the EV performance is in agreement with the simulation results.