Research On Modeling And The Energy Saving Control Strategies Of Hybrid Hydraulic Excavator

Construction machines especially hydraulic excavators have been paid much attention in the field of energy saving as result of their widespread usage, high oil-consumption and a great deal of exhaust emission. It has been difficult to further improve the energy saving effect by improving the performance of engine and hydraulic system. Though there is still considerable room for improvement in the power matching, it is limited by existing power system. A new way of thinking about the research of the energy saving is proposed for the conventional hydraulic excavator power matching due to the successful application of hybrid cars. This thesis mainly research on the methods and theories of improving the distribution of engine operating point by using hybrid system and validated by simulation at last.Firstly, this thesis introduces the structure and working principle of single bucket hydraulic excavators. Then this thesis decides to adopt the parallel hybrid power system through comparison and analysis of nowadays developed hybrid power system, such as:serial structure, parallel structure and series-parallel combined structure.After determined the hybrid power system, on the condition that load power demand is satisfied, with consideration of all influencing factors, each element’s parameters are ensured by analyzing all kinds of operation conditions.The control strategy design of the energy management between engine and electric motor is the key to realize the anticipated energy saving goal. So this article make a special study focused on this core content and improved the fuzzy control strategy which used in the hybrid cars. According to comparing the energy saving effectiveness of fuzzy logical control strategy, this thesis designed the Instantaneous Optimization Control Strategy which aimed to minimize the instantaneous equivalent consumption. According to the simulation and comparison of traditional hybrid hydraulic excavator and each with different control strategies, hybrid hydraulic excavator with fuzzy logical control strategy and Instantaneous Optimization Control Strategy reduce comprehensive fuel consumption respectively by about15%,20% compared with traditional hydraulic excavator, this had not included several energy saving aspects such as the cancellation of engine’s idle speed.