| Hydrogen-oxygen Proton Exchange Membrane Fuel Cell(PEMFC)is an electrochemical power generation device with high conversion efficiency and power density which has broad application prospects in the military.As the main pressure control element in the fuel cell gas supply system,the electric proportional pressure reducing valve directly affects the performance of the entire fuel cell system.The high-precision control of the pressure on both sides of the membrane is important to ensure the safe operation of the PEMFC system.At present,The research on pneumatic proportional pressure valves is still not comprehensive,and the pressure control performance is dissatisfactory.Based on the research background of the hydrogen-oxygen fuel cell gas supply system,the paper designed a group of hydrogen-oxygen pneumatic proportional pressure valves with high-precision and high-stability,and realize the optimization of structural design and characteristic analysis.The matching of response characteristics and closed-loop control law applied to the valve stystem to achieve pressure synchronous control between the hydrogen and oxygen valve which ensure safe,stable and efficient operation of the fuel cell.First of all,a new type of non-overflowing pneumatic proportional pressure valve with a bellows feedback cavity was designed,combining the requirements of the working conditions in the gas supply system and the gas characteristics of hydrogen and oxygen.The whole structural design and material selection were completed.The force characteristics of bellows components were tested which is the key pressure-sensitive structure in the valve.Then,the mathematical model of the pneumatic proportional pressure valve was established,and a nonlinear simulation model of the valve was built in Matlab/Simulink to realize the open-loop dynamic and static characteristics analysis.The influence of key structural parameters and changes of upstream and load conditions on dynamic and static characteristics is analyzed,and the mechanical response performance is optimized.On this basis,anti-windup PI closed-loop control law is presented to achieve high-precision and high-stability pressure response characteristics.At the same time,establish a flow field simulation model in Fluent,which realized the analysis of the pressure distribution near the valve port and the flow characteristics of the valve in order to play a guiding role in the design of the valve.Finally,this paper presented a pressure synchronous control strategy for the pressure deviations between cathode and anode.By matching the structural parameters and control characteristics of the hydrogen valve and the oxygen valve,the response synchronization between two valves is obtained.And further presentsed double-loops coupling pressure control strategy,presented a masterslave closed-loop control strategy,PI-based double-loops coupling pressure control strategy and fuzzy PI-based double-loops coupling pressure control strategy,to achieve the adaptive control of the pressure deviations between cathode and anode during multiple disturbances,and realize the synchronous control of pressure between cathode and anode. |
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