A novel digital power controller for fuel cell/ battery hybrid power sources

Hybrid power sources composed of fuel cells and batteries provides higher peak power than each component alone while preserving high energy density, which is important and necessary to modern electronic equipment. An appropriately controlled DC/DC power converter handles the power flow shared by the fuel cell and the battery. The power converter needs to be regulated to balance the power flow to satisfy the load requirements while ensuring the various limitations of electro-chemical components such as battery overcharge limit, fuel cell current limit, etc. Digital control technology may be applied in the power electronics controls due to many advantages over analog control such as programmability, less susceptibility to environmental variations, and fewer part counts. This paper presents a novel digital power controller for fuel cell/battery hybrid power sources. The power controller circuit consists primarily of a synchronous buck converter that is controlled by a single-chip PIC microcontroller, and features small size and light weight. The user can set the fuel cell current limit, the battery current limit and the battery voltage limit in the control software. The control software implements multiobjective coordination of the power converter. The digital power controller was first tested through processor-in-the-loop simulation and then validated on the real hardware. Simulation and experiment results are given in the paper.