Research On Energy Management Of Solid Oxide Fuel Cell/Lithium Battery Hybrid Power System

The world is facing a deterioration of the environment.It is generally believed that the burning of fossil fuels is one of the main reasons.The use of clean energy to replace fossil fuels has become the focus of attention of researchers and governments around the world.Solid Oxide Fuel Cell(SOFC)is a fuel that is produced by electrochemical reaction.The reactants are water and carbon dioxide.It is a promising energy source for future development,so it is necessary to study it.SOFC there is a problem that the dynamic response of the power output is slow,and the sudden increase in load power will threaten the safe operation of the SOFC.In view of this,this thesis uses solid oxide fuel cell/lithium battery hybrid energy structure,lithium battery as energy buffer unit to ensure that SOFC can be in safe and stable operation when the load power surge.In this thesis,SOFC/lithium battery hybrid energy system uses the overall structure for the SOFC output by a step-up DC/DC converter SOFC instability of the low output voltage boost to a stable DC bus,lithium battery by Bi-DC/DC converter Parallel to the SOFC boost converter output,the load connected with the DC bus.Based on the average switching model of bidirectional DC/DC,the transfer function of the duty cycle to the input current of inductor,the input current of inductor to the lithium battery charging voltage,the duty cycle to the output current of inductor,the output current of inductor to the DC bus voltage is deduced.The converter operates in the Buck discharge mode and the Boost charge mode of the discrete PI controller,which precisely controls the lithium battery to absorb and release energy.Then,in order to make the lithium battery work in the normal range,this thesis estimates the state of charge(SOC)of the lithium battery by using the Kalman filter to correct the initial SOC combined with the time integral method.The energy management strategy is that the SOFC assumes the average component of the load power,and the lithium battery assumes the rest of the load power.Finally,the controllable switching power supply is used to simulate the power output of the SOFC,the load of periodic power changes in the marine buoy is tested as the test condition in the laboratory,which proves the effectiveness of the method in ensuring the safe and stable operation of the SOFC.