Research On Control Strategy Of Fuel Cell Hybrid Energy Management System

As a new type of high-efficiency and pollution-free energy source,fuel cell is highly regarded by many experts and scholars all over the world because of its clean,low noise,long operating cycle and high energy conversion efficiency.However,the fuel cell itself has low power density,soft electrical output characteristics,and significantly lagging response to sudden load changes.When it is used alone as a power supply energy source,the output voltage fluctuates greatly and the power supply reliability is not high.In practical applications,it is necessary to add DC converters and corresponding auxiliary energy storage power sources to form a fuel cell hybrid power supply system,effectively use the connected auxiliary energy storage system,improve the flexibility of the power supply system through its dynamic adaptability,and achieve an extension The effect of fuel cell life cycle.The access of the DC converter also expands the effective power supply range of the energy source,and ensures that the fuel cell system efficiently and stably provides electrical energy.First of all,a hybrid power supply system with a fuel cell as the main energy source and a super capacito(SC)r as an auxiliary energy storage system is connected to the DC bus through a DC/DC converter to output within the effective range of the energy source,avoiding a large amount of energy The fluctuation causes irreversible damage to the power supply device.The fast power response of the supercapacitor and its high power density characteristics make up for the lack of performance of the fuel cell.Aiming at the fuel cell hybrid power supply system proposed in this paper,energy management and control is performed,and the rule-based energy management strategy is used to optimize the power output response of the hybrid power supply system and improve the conversion efficiency of available energy,thereby improving the economics and reliability of the power supply system.Then it proposes an energy management strategy to determine the target power value through the auxiliary state of charge(SOC)of the energy storage system and the load side demand changes during the unit operating cycle.This strategy is based on the rule fuzzy logic theory,based on the load The membership function of the required power and the state of charge of the supercapacitor and the IF-THEN rule distribute the power of the fuel cell,so that the power supply system quickly acts on the change of the load,avoids that the required power on the load side cannot be met within a certain period of time,and guarantees The power supply of the system is reliable.Secondly,using the state machine energy management strategy,at the control level of the hybrid power supply system,based on the state machine,the three SOC working intervals of the super capacitors are reasonably divided.In different working intervals,combined with the variation range of the load-side demand power,the fuel cell is determined.Expect the output power,plan the different operating states of the system,and compare it with the SOC and load demand power under actual operating conditions,and finally adjust the output power of the fuel cell system according to the proposed state rules.Finally,in order to verify the theoretical analysis,the paper builds a fuel cell hybrid power supply simulation model on the MATLAB/Simulink platform,respectively uses the fuzzy control strategy and state machine control strategy to distribute the energy to the system,and in turn conducts energy management results under PI control Comparison,simulation results show that the power supply system adjusts the load demand power,avoids overcharging or overdischarging of the energy storage medium during the entire working period,achieves the purpose of extending the life of the fuel cell,and verifies the fuel cell hybrid power supply system.The correctness of the two proposed energy management strategies.