Research On Nonlinear Dynamic Behavior Analysis And Control Methods Of Microbial Fuel Cell

The exploration and utilization of energy has greatly promoted the development of the world economy and human society.Although the use of energy has undergone a diversified transformation after entering the new century,but currently,use of energy mainly relies on fossil fuel combustion.Diversifying the use of energy to alleviate the damage caused by fossil energy to the environment is a major research proposition.Microbial Fuel Cell(MFC)is a new type of biomass energy that emerges after new energy sources such as wind energy and solar energy.The research and development of microbial fuel cells has added a new utilization mode to the utilization of energy.At present,the research on microbial fuel cells mainly focuses on two aspects: one is to study how to grea tly improve the energy density of MFC from the structure and materials,and the other is to consider how to make the voltage output of MFC stable and reliable from the perspective of power control.The research history of structure and materials is long,a nd great research results have been achieved.However,due to the short research time of power control,the relevant research literature is not as abundant as materials and structures.Therefore,this paper mainly focus on the power supply control.The main research contents are as follows:1)The working principle and typical structure of microbial fuel cell are briefly introduced,and making a SIMULINK model,the simulation model is used to analyze the nonlinear dynamic behavior,that is,the influence of input parameters on output voltage is obtained.The input variable which has the greatest impact on the output voltage is taken as the control variable in the optimal voltage control,and the output voltage is determined as the controlled variable.2)The linearized continuous state space model is extracted as the reference model of model reference adaptive control when the microbial fuel cell operates near the working point for the characteristics of input and output nonlinear operation of microbial fuel cells.The model with changing internal matrix parameters is used to simulate the actual controlled object.Making some state variables and output voltage of the controlled object can track the reference mo del in a certain error range near the working point by adaptive adjustment.3)To overcome the disadvantage of model reference adap tive control that the control effect becomes worse when it greatly deviates from the equilibrium point,a feedforward fuzzy logic PID control strategy is used,it is especially suitable for nonlinear,hysteresis,mathematical models such as microbial fuel cells that are idealized object.The simulation analysis shows that the control strategy can continuously track the set value of the voltage,possessing the advantages of short adjustment time,small overshoot,small steady-state error and strong anti-sudden interference ability.4)How to select the control sequence in order to obtain the minimum value of the defined economic objective function when constraints on the state variables and control variables of the MFC system are exist,further consideration is necessary.The economic model predictive control(EMPC)method is to design the control law around the problem that the economic objective function obtains the minimum value,this kind of problem of considering the optimization of economic indicators in the operation of the system is more in line with the actual situation of industrial processes: calculating the economic objective function in the prediction time domain after each moment and obtaining a control sequence,t aking the first component to add on the control system,and re-calculating the recalculation control sequence at the next moment to cycle.