Compensation of the low frequency current ripple in single phase grid connected fuel cell power systems

Due their high efficiency, even at partial load and on small size units, fuel cell stacks are suitable for distributed power generation networks,. However, power drawn by single phase grids contains a low frequency oscillation that generates a large ripple on the stack output current. Such a current ripple is able to shorten the fuel cell lifetime, to worsen the stack efficiency and to reduce the available peak power. Therefore, passive and active current ripple reduction techniques have been proposed in the past exploiting bulky electrolytic capacitor banks or expensive active filters. In the proposed paper a new approach is suggested where an active filter is integrated into the converter, without introducing extra power devices. According to the proposed approach the size of the electrolytic capacitor bank can be largely reduced, thus improving the reliability, while lowering costs and size.