| With China’s "double carbon" development strategy goal,green and environmentally sound sustainable growth has been the main industry development trend.In the new era of requirements,the logistics industry has been developing rapidly and the related research has become a hot spot in the industry.As a widely used handling machine in logistics industry,electric forklift has the features of easy handling,less noise,no contamination and so on.Energy and environmental problems are nowadays paid increasing attention,and the study of forklift truck saving energy technology has already become the key orientation of the sector development.Aiming at the serious problems of energy loss and battery life degradation caused by frequent starting and braking of the gantry system lifting and lowering and drive system during the operation of electric forklift,a joint energy recovery method of electric forklift truck was proposed on the basis of working features.Firstly,the method of joint energy recovery and reuse of potential energy of gantry descent and kinetic energy generated by braking is proposed based on the analysis of typical forklift working characteristics and the use of super capacitorbattery pack as energy storage device;then,the simulated market of joint recycling system is built by AMESim-Simulink water;Finally,the proposed method and the built joint simulation model were used to carry out simulation analysis for a complete handling cycle,illustrating the correctness of the method and model.The main research work of the thesis is as follows:(1)With reference to JB/T3300-2010 test working condition standard,the actual operation process of the electric forklift is analyzed,the working characteristics of the gantry system and the drive system are summarized,and on this basis,the displacement curve of the gantry system and the speed curve of the drive system are drawn,and the principle and scheme of potential energy recovery and braking energy recovery are established.(2)According to the joint collection and recovery scenario proposed,the features of all kinds of energy accumulation units are compared,and it is determined that the supercapacitor-battery set is used as the energy recovery and storage unit,and the respective advantages of supercapacitor and battery are brought into play.Also,to solve the unstable voltage problem in the energy storage device,a DC/DC convertor is introduced to link the supercapacitor to the DC/DC converter,and then connect it in parallel with the battery to improve the charging and discharging voltage variation as well as the charging efficiency problem and increase the energy utilization of the system.(3)Simulation models of electric forklift gantry hydraulic system and braking system energy recovery were established and combined on AMESim platform respectively.The electro-hydraulic position servo control system is developed in Simulink software,and the hydraulic cylinder lift displacement in the hydraulic system is precisely controlled by using fuzzy PID adaptive algorithm.(4)Taking a typical working cycle of a 2t electric forklift in a warehouse as an example,the proposed joint energy recovery method is illustrated,while the recovery effect of the joint energy recovery system is assessed by adjusting the load weight,lifting height and charging current.The test results show that: the load size and lifting height are related to the potential energy recovery efficiency,the bigger the load,lower the descent height,the greater the amount of potential income collected;the stopping flow is linked to the braking energy recovery efficiency of the forklift,and the braking flow decreases,the greater the energy recovery efficiency.Thus,it is clear that the combined collection energy plan can be used to achieve a higher energy recycle rate of up to 55.3%,avoiding the loss of effort and yielding significant energy savings,and verifying the reasonable reuse of the combined reuse energy recovery system described in this paper. |
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