The Design Of Bi-directional DC/DC Converter Applied In Super-capacitor Storage Systems

With the development of economic, the power quality and reliability have becoming more and more important to human. And the problem of the power system is the imbalance of power generation and grid load, so adding energy storage system at the user load side to solve the power imbalance problem between supply and demand is a very significant thing.In this paper, the storage technologies used in power systems were introduced; The super-capacitor device and the typical applications of super-capacitor energy storage system were introduced; and the various kinds of bi-directional DC/DC converter for the super-capacitor energy storage system were introduced. Because of the single super-capacitor storage energy limit, Super-capacitor energy storage system needs a certain number of super-capacitor series-parallel combined to achieve the required storage energy. This paper introduced all kinds of super-capacitor equivalent circuit by referencing to the literature, and introduced a series-parallel combination methods of the super-capacitor bank using one of the equivalent circuit.A small super-capacitor energy storage system is built. The super-capacitor bank, the main circuit hardware and the control circuit hardware used in super- capacitor energy storage system is designed. Because the super-capacitor energy storage system used in this paper is to solve the problem of the imbalance between energy supply and demand. So, the bi-directional DC/DC converter used in the super-capacitor energy storage system has two operating modes: When the super-capacitor energy storage system absorbed energy from the grid, the bi-directional DC/DC converter works in Buck mode. When the super-capacitor energy storage system release energy to the grid, the bi-directional DC/DC converter works in Boost mode. This paper modeling the bi-directional DC/DC converter in the two operating mode, at the same time, according to the system parameters, the closed-loop parameters is designed. Finally, experimental is done when the super-capacitor energy storage system in the working two mode, simulation and experimental results show that through the design of thesuper-capacitor bank and the bi-directional DC/DC converter closed-loop controlparameters in the super-capacitor energy storage system, the super-capacitor energystorage system can solve the problem of power imbalance between supply anddemand.