Design and implementation of a DSP based fuel cell / battery hybrid power source

Currently there is considerable R&D activity in the field of fuel cell (FC) technology as an efficient and clean power source for both stationary and transport applications. This paper describes the development of a fuel cell/battery hybrid power source for a stationary domestic power application, details the control systems underpinning this system and describes some preliminary experimental results. The authors believe that the fuel cell/battery hybrid power system is the most cost-effective solution for domestic power applications. This recognizes that a typical domestic power profile can have a peak to average power ratio of between around 9-15, and hence a fuel cell only system would significantly over-rate the fuel cell to satisfy peak power and consequently suffer from poor utilisation. The hybrid system avoids this by using battery power to meet instantaneous peak power and the fuel cell as a base load / battery charging element. The objective of this paper is to consider the power electronic interface from a fuel cell as a low voltage DC source, to a higher voltage storage battery and possible DC load, i.e DC/DC booster, and ultimately a DC/AC inverter for utility connection. This paper will describe the system design and experimental results over a 7-hour test period using a DC load profile only, monitored by an LF 2407 digital signal processor (DSP).