Study On Control Strategy Of Plug-in Hybrid Electric Forklift

Forklift is a kind of heavy usage industrial vehicle, the application of hybrid technology used in forklift has great significance to reduce fuel consumption and emissions. At the same time, the weight of the hybrid system can ruduce the weight of the balance weight of forklift. So, the hybrid technology is particularly suitable for forklift. Plug-in hybrid electric forklift (PHEF) can make full use of the electricity from the grid and reduce the fuel consumption and emissions furtherly compared with traditional hybrid electric forklift. The development of PHEF can promote the development of smart grid and distributed energy.The background of this thesis is a hybrid forklift R&D project. Firstly, the structure of the PHEF and the main parameters were determined, a forward simulation model was established in Matlab/simulink. This forward simulation model included the models of engine, motor, driver, vehicle dynamics, lifting device and so on.Then, the multi-modes layered logic rule control strategy and the fuzzy logic control strategy were designed based on the characteristics of PHEF. The design process and software implementation were introduced in detail. The simulation experiments in certain circulation condition were did and the results indicate that PHEF which used multi-modes layered logic rule control strategy has better oil-saving performance than traditional fuel forklift, what’s more, The oil-saving effect of fuzzy logic is more obvious. These two control strategies can meet the requirements of dynamic performance and battery SOC. The prototype test was also done and the experimental results and simulation results were compared, the results show that the forward simulation model and control strategy are effective.Finally, the particle swarm optimization (PSO) was used to optimize the fuzzy control parameters in order to improve the fuel-economy furtherly. And the results confirm it.