Frequency Electro-hydraulic Systems Based On Slip Frequency Vector Control Of Electric Forklift

The battery forklift truck,with three-phase asynchronous motor for frequency control , more environment-protective and efficient ,is now becoming a new trend in development in place of the diesel engine one both in and out of China.The motor controller, as the core technology of battery forklift ,decide the functional improvement of the truck .Up to the present,the researchers in our country mainly focus on the stability, structure optimization and serviceability technology of forklift.Compared with advanced technology overseas, the researches and development of the asynchronous motor frequency control on AC battery forklift electro-hydraulic system,energy-saving and power matching are still to be improved,which makes the realization of asynchronous motor speed regulation on AC battery forklift electro-hydraulic system a hot topic to be researched. To meet the demand of developing battery forklift in SUNWARD Co.as well,the system of frequency control for electro-hydraulic system on AC battery forklift is being researched in the paper, and the main content is as follows:First, the development of battery forklift and AC frequency control technology was analysed comprehensively and the defect of the present technology was found out.Second, the strategy of using slip-frequency-type vector control to replace the scalar control was put forward ;the performance properties of the AC battery forklift, especially the load behavior of the hydraulic system, was researched to simplified the hydraulic system model .Then, the slip-frequency vector control electro-hydraulic system on AC battery forklift was mathematically modelled.Third, based on the theoretical analysis and mathematical modelling of the system,the asynchronous motor slip-frequency vector control system was simulated using Matlab/Simulink software; considering the simplified mathematical model of the hydraulic system , co-simulation was made to simulate the forklift's performance integrating the advantages of both Matlab/Simulink and AMEsim softwares.The simulation experiment mainly focus on two work conditions—the unloaded and full loaded performances.At last, comprehensive tests was made on SWFE15AC-4F1 battery forklift of SUNWARD Co. by modern test skills and advanced measuring instruments, to verify and certificate the accuracy and feasibility of the theoretical analysis and simulation experiment on slip-frequency-type vector control technology of AC battery forklift electro-hydraulic system.As the researches suggest,using slip-frequency-type vector control to drive AC battery forklift electro-hydraulic system was of quick transient speed response , less oscillating in torque and current,and good steady -state capacities .