Research On Multiple Bi-directional DC/DC Converter Of Hybrid Energy Storage System

The renewable energy which is friendly to environment has get more socialattention. The power system which consists various renewable energy sources andenergy storage devices can overcome many shortages of the renewable energy powerequipment to achieve efficient use of the renewable energy and stable output. In apower system contains renewable energy power sources and energy storage devices,each renewable energy source and energy storage devices needs a DC/DC converterto connect with the DC bus. With integrating all the DC/DC converters into oneinterface device, not only the topology of renewable energy system can be simplified,but also reduce costs, realize central control and improve the performance of system.Through reading the domestic literatures and foreign literatures, classifys themultiport bi-directional DC/DC converters proposed by domestic scholars andforeign scholars, analyzes the characteristic of each topology, then chooses thethree-port half-bridge bi-directional DC/DC converter as the research object of thispaper. Through analyzing the operating principle of three-port half-bridgebi-directional DC/DC converter in different operating condition, deduces its stateequations in six switch-status and the state-space average model. Using thestate-space average model of three-port half-bridge bi-directional DC/DC converter,establishes its small signal model by adding tiny disturbances, then uses the smallsignal model to deduce the converter’s transfer functions of input-output andestablishes its dual-loop control system of current-voltage; designs and optimizes thecurrent control loop and the voltage control loop of the converter by Bode diagram,then simulates and proves the performance of converter’s control system in theMatlab/Simulink.At the end of this paper, introduces the strategy of energy management forhybrid energy storage system in micro-grid laboratory of Yunnan Electic PowerResearch Istitute, and proves the three-port half-bridge bi-directional DC/DCconverter can work steadily through the simulation of coverter operating in differentcondition.