Adaptive Control Strategy For Long-term Stable Operation Of Direct Methanol Fuel Cell

As one of the most environmentally friendly and efficient fuel cell technologies,Direct Methanol Fuel Cell(DMFC)has the advantages of high energy,non-pollution environment,good safety,simple structure and easy storage.It has a very broad development prospect in the fields of electric vehicle,military industry and communication.It can maximize the interests especially on the road of commercialization.However,methanol penetration,polarization and catalyst degradation affect the performance of DMFC.In the meanwhile,the voltage deviation and performance attenuation caused by the long-term operation of the DMFC seriously hinder its commercial process.At present,researchers have studied the performance compensation of a certain point in the long-term operation of DMFC by changing the operating parameters,but they have not carried out a research on the performance compensation of a certain working interval in the long-term operation of DMFC.Based on the research idea of changing from point to line,this paper proposes a long-term stable operation adaptive control strategy,which can improve the voltage stability by reducing the voltage deviation and realize the long-term stable operation of the battery.This paper makes a systematic study on this problem.(1)Based on the purpose of the experiment,a DMFC test platform is built,which can real-time control multiple operation parameters and monitor the results.The DMFC consists of a single cell system,three input systems and three output systems.The air supply system,methanol supply system and temperature regulation control constitute the three major input systems;the carbon dioxide concentration monitoring system,the load control system and the electrochemical workstation test system constitute the three major output systems.The performance of DMFC was characterized by polarization curve,power density curve and en ergy conversion efficiency.According to the experimental data,the results show that the performance of DMFC showed a periodic decline,the performance decreased significantly under long-term operation,and the performance decreased in a short time.(2)The relationship between DMFC performance degradation and running time is established by using the meta model modeling method.On the basis of the results,the decision coefficient R2 is used as the evaluation index to optimize the self inspection method and the retention one detection method,and the best meta model is selected.The results show that the model can well represent the relationship between DMFC performance degradation and running time,and predict the degree of degradation in the future time,which lays the foundation for the long-term stable operation control strategy.(3)A long-term stable operation adaptive control strategy of DMFC is proposed,and the model prediction and experimental verification are carried out in different time periods.The results show that the regulation strategy proposed in this paper is reasonable and feasible.It can predict the attenuation of DMFC in different degrees and give the operation parameters.By adjusting the operation parameters and reducing the voltage deviation,it can implement stabilization operation over a long period of time of DMFC.A 130-hour decay experiment was performed on the direct methanol fuel cell performance test platform and experimental data was obtained to establish a meta-model between DMFC performance decay and operating time;an adaptive control strategy for long-term stable operation was proposed and experimentally verified.This strategy helps to better control the output voltage of the DMFC system.