Research And Design Of Energy Management Strategy For Fuel Cell Hybrid Power System Of Forklift Truck

Proton exchange membrane battery is a new type of power generation device that uses hydrogen as fuel.It is not restricted by the Kano cycle.It can operate in a wide voltage range,and the by-product is only water,so it has potential to replace fossil energy.But it is limited by the development level of membrane electrode materials.In the face of the complex and changeable power demand of the forklift,it is difficult to follow the strong variable load and unable to recover the braking energy.Therefore,it is often combined with the energy storage component to form a hybrid power system in the actual operation.Firstly,based on the existing technical indicators of forklift,the selection design of hybrid power system is carried out.Because the working conditions of the forklift truck are changeable,this paper designs a test method based on the limit condition,obtains the cycle condition of the forklift,and studies the advantages and disadvantages of the topology of the four basic hybrid systems.After comparing the control principles and applicability of the four kinds of energy management strategies,the state based energy is designed.The control scheme of the Energy Management Strategy(EMS)is designed to control the output power of the fuel cell by dividing the lithium battery SOC and the load demand power interval.At the same time,the fuzzy logic EMS is designed to optimize the rationality of the interval division,and the two methods of Mamdani and Sugeno are used to defuzzification.Two fuel cell output power control modes are obtained.Then,this paper designs an evaluation function based on the residual value of the hybrid system in order to solve the problem that the reference amount of the general evaluation index is more and the result is not intuitionistic.The function mainly consists of three parts: residual life of fuel cell based on operating conditions,residual life of lithium battery based on cycle life and hydrogen consumption of fuel cell system,and the unification of reference amount through initial value and operation cost.On this basis,the modeling and imitation of the hybrid dynamic system and evaluation function are made.In the real experiment,the influence of the above three strategies on the residual value of the forklift truck under extreme conditions is analyzed and compared.Finally,in order to verify the effectiveness of the energy management strategy involved,with the power and energy requirements of the forklift running,the PEMFC system,the hydrogen supply system and the battery pack were selected and the parameters were calculated.The PEMFC/ hybrid power test platform was built,and the STM32 was designed as the hardware carrier of the energy manager.The software flow of hybrid power system,including communication of various devices,parameter detection and transmission,and the algorithm flow of EMS,is used to verify the hardware function of the energy manager by designing step power test.At the same time,the original EMS algorithm will result in the output power of PEMFC production mutation.The control scheme and algorithm flow of the original EMS are improved by the constraint conditions of the output change rate of the electric reactor.Finally,the improved EMS is proved to be more advantageous in prolonging the life of the reactor by designing the equivalent reduction simulation experiment of the limit condition of the forklift.