Energy Management of a Fuel-Cell Serial–Parallel Hybrid System

In this paper, a serial-parallel hybrid (SPH) power system formed by a fuel cell (FC), an auxiliary storage device (ASD), and the current-controlled dc-dc converters responsible for the power management are realized by using the digital signal controller (DSC) TMS32F28335. The main energy management goal is to transfer energy from the sources (FC or ASD) to the load while ensuring dc bus voltage regulation and high power conversion efficiency. In addition, a safe and reliable operation of the system has to be achieved. The selected converter and its controller features are noninverting voltage step up and step down, high efficiency, regulation of input and output currents and low ripple values, and the ability to change from input to output current regulation loop, suddenly and smoothly, and vice versa. All these features allow it to be positioned in different FC system localizations and simplify the design of the master control. Simulation and experimental results have been validated on a 48-V 1200-W dc bus.