Dsp Based Bi-directional Interleaved Dc-dc Converter for Energy Storage Application

The central part of an energy storage system is the DC-DC converter which connects the ultracapacitor pack or the battery pack and a DC bus of an energy system. In this paper the bi-directional converter which operates in discontinuous conduction mode is designed in order to reduce the costs and remove the current control loop in each phase. High current ripples associated with this mode operation are then alleviated by interleaving. In order to control this kind of DC-DC converter the digital signal processor (DSP) is used. Such converter can be used for charging and discharging of accumulators or ultracapacitors. The charging mode of the accumulator differs from that of the ultracapacitor, the discharging mode differs from the charging mode for both devices, too. In the paper the software algorithm is presented that shows how transition from one mode to the other is done. Digital control of the DC-DC converter makes it easy and quickly to configure.