Research On Power Management And Air Supply Control Of Fuel Cell Bus Power Syste

The Polymer Electrolyte Membrane Fuel Cell(PEMFC)is an energy power device that can directly convert hydrogen energy into electricity.Compared with fossil-fuel-based generation systems,PEMFC possesses the merits of high specific power,fast start-stop,better refueling time and driving range that is widely used in transport sector.However,in the face of complex driving conditions,the PEMFC has the poor durability due to the frequent load fluctuation,which will hinder its commercial application.Therefore,the fuel cell durability and fuel economy are major considerations for hydrogen fuel cell vehicles.In this research,the PEMFC air supply system control and fuel cell/battery hybrid system power management are investigated for a medium-sized hydrogen fuel cell hybrid bus.The main content of this paper is as follows:(1)Firstly,the hybrid power system model of FCHEB is established for subsequent control of the fuel cell air supply system and the design of the hybrid system power management strategy,which includes the control-oriented PEMFC system dynamic model,boost DC/DC converter,Lithium-ion battery,permanent magnet synchronous motor(PMSM)and vehicle longitudinal dynamic system considering the mechanical transmission losses.(2)Due to the constraints of external equipment conditions of PEMFC,the cathode gas partial pressures of fuel cell are usually unmeasurable,which brings difficulties to the control of air supply systems.To address this problem,a Hyperbolic Tangent Function Extend State Observer(HTF-ESO)is proposed to observe the cathode gas pressure in real time.The results show that the improved ESO effectively alleviates the initial differential peaking phenomenon compared with the conventional ESO and reduces the initial estimation error of the cathode gas pressure.In addition,the sliding mode control and PI control methods were established respectively with the Oxygen Excess Ratio(OER)as the control target.The comparative analysis results show that the sliding mode control has better robustness and faster response,and can better maintain the fuel cell OER within the optimal range.(3)The development of real time advanced and stable electric power management strategy is vital to making the hybrid powertrain system more efficient and cost-effective.In order to address the power management of the fuel cell bus hybrid power system,a realtime nonlinear adaptive control(NAC)power management strategy is formulated for power management of FCHEB.Furthermore,the NAC-based strategy with quadratic Lyapunov function is set up to guarantee the stability of closed-loop power system,and the power split between fuel cell and battery is controlled with the durability consideration.Finally,two real-time power management strategies,state machine control(SMC)and fuzzy logic control(FLC),are implemented to evaluate the performance of NAC-based strategy,and the simulation results suggest that the guaranteed stability of NAC-based strategy can efficiently prolong fuel cell/battery lifespan and provide better fuel consumption economy for FCHEB.