Ultracapacitor application and controller design in 400 V DC-powered green data centers

The integration of solar power, batteries and ultracapacitors to increase the reliability of the power supply for dc-powered data centers and reduce carbon emissions is investigated in this paper. The availability of ultracapacitors that have very high power densities and charge/discharge cycling capability characteristics enable smoothing solar power intermittencies. Four typical weather conditions are simulated for solar power generation. A battery/ultracapacitor energy storage unit is controlled with the goal of improving battery lifetime. Simulation results verify the proposed ideas.