Research On Control Strategy Of Brake Energy Recovery For Hybrid Bulldozer

With the increasing attention to the environmental and energy problems,the demand for energy-saving and emission-reduction technologies is getting higher and higher in the engineering machinery industry.The hybrid bulldozer is a typical vehicle with high emission and high fuel consumption.In order to further save energy and reduce emissions,recycling of the regenerative braking energy of bulldozers has become one of the key technologies that are feasible.According to the running characteristics of the hybrid bulldozer,the braking energy recovery of the bulldozer can be recovered by the rational distribution of the mechanical friction braking force and the motor regenerative braking force during the vehicle braking,so the different braking force distribution strategy will directly affect the recovery effect of the regenerative kinetic energy.In this paper,a series hybrid bulldozer is taken as the research object.The braking process of the bulldozer is carefully analyzed.After studying several common braking force distribution strategies,the following results are obtained.(1)By analyzing the composition of the hybrid bulldozer,the structure of the regenerative braking energy recovery system of the hybrid bulldozer is established,and the different braking energy recovery modes are analyzed.(2)Based on the analysis of the influencing factors of bulldozer braking,a regenerative braking energy recovery control strategy based on vehicle speed,braking intensity and super capacitor SOC as control variables is proposed.Using a combination of theory and data,a regenerative braking energy recovery system model was established using the MATLAB/simulink module(3)Through the analysis of the regenerative braking energy recovery control strategy based on the deterministic rules,the vehicle speed,the braking intensity,and the super capacitor SOC threshold are determined and a control strategy based on the determination rule is established.The simulation analysis shows that the control strategy based on the determined rules can effectively recover 19.4% of the regenerative braking energy under the comprehensive conditions.(4)Combining with the working characteristics of bulldozers,a fuzzy-based regenerative braking energy recovery control strategy is proposed.Fuzzy controller input,output and fuzzy rules are designed based on practical experience,and a complete control strategy is established.Simulation analysis shows that the fuzzy-based control strategy can effectively recover 24% of the regenerative braking energy under the comprehensive conditions.(5)The simulation analysis based on the fuzzy and control rules based on the determined rules shows that the fuzzy-based regenerative braking control strategy can better dynamically allocate the regenerative braking force and the mechanical braking force,and has similar safety performance in braking.In this case,the braking energy can be recovered more effectively,and the regenerative braking energy recovery rate is significantly improved.