Research On The Health Control Of Hybrid Energy Systems With Proton Exchange Membrane Fuel Cells

Proton Exchange Membrane Fuel Cell(PEMFC)is an excellent green energy source with high efficiency and low pollution,which is widely used in the field of new energy vehicles and stationary power generation.In this thesis,we investigate the control strategy of PEMFC from the perspective of extending the service life of fuel cell and improving the durability of the cell.The main work and innovation points are as follows:Aiming at the high cost of fuel cell aging experiment,a fuel cell aging behavior modeling study is conducted and a fuel cell decay model is established.The model uses Electrochemically Active Surface Area(ECSA)as the main factor to evaluate the decay of cell performance to simulate the performance state of fuel cells,which reduces the cost of physical experiments and provides an evaluation method for the subsequent comparison of energy management algorithms.To address the problem that the internal health state of the fuel cell is difficult to characterize,the electrochemical impedance spectroscopy technique is used to identify the parameters of the equivalent circuit model,and the ECSA value of the cell is solved by the polarization impedance parameter in the equivalent circuit parameters,so as to construct a link between the internal aging and external characteristics of the fuel cell,and quantitatively describe the health state of the fuel cell.To address the problems of slow fuel cell start-up and frequent fluctuations in external load leading to fuel cell performance deterioration,lithium batteries are introduced as auxiliary energy supply elements for hybrid power systems.Considering the safety problems that may exist in the process of lithium battery operation,the state of charge(SOC)of lithium battery is estimated based on the adaptive unscented Kalman filter algorithm,and the SOC of lithium battery is controlled in a safe range.A topology of a multi-stack PEMFC/lithium battery hybrid energy system is designed for fuel cell applications in high-power scenarios to make up for the low output power of a single-stack fuel cell.To extend the system lifetime,a health condition-based energy management strategy is designed,and a simulation model of the hybrid energy system is built to validate the energy management strategy.The health condition-based energy management strategy proposed in this thesis is compared with the balanced allocation strategy and the sequential chain strategy for experiments.The experimental results show that the performance degradation of the fuel cell using the health condition-based energy management strategy is minimal,which proves the effectiveness and advancement of the proposed strategy.