Research On Parameter Design And Control Strategy Of Hybrid Excavator Power Assembly

Hydraulic excavators are the primary equipment in project construction by virtue of multiple purposes and strong operation adaptability,and the usage amount and market holdings increase year by year with the development of various countries.At the same time,as hydraulic excavators have the disadvantages of huge conventional energy consumption,poor discharge,low efficiency,etc.,under the circumstance of increasingly severe energy shortage and environment deterioration all over the world,it is urgent to realize energy conservation and emission reduction.Hydraulic excavators are in the structural arrangement form that engines are under direct driving load,and the fuel economy of engines are significantly influenced by load fluctuation.Traditional hydraulic excavator energy-saving technologies tend to be mature,and it is difficult to break barriers and achieve substantial effects in a short time,and it is urgent to seek for new technical solutions.The hybrid technology provides new solutions for hydraulic excavator energy conservation and changes the power-driven structure of excavators.To buffer the impact from load power through the auxiliary power source can stabilize engines in a high-efficiency work area and improve their fuel economy.At present,the hybrid technology co-driven by engines and electrical machines is the research focus in the field of Construction machinery.However,compared with the mature vehicle hybrid technology,the hybrid Construction machinery in the primary stage of research,due to the significant differences with automobiles in driving load and energy recycling modes,it is necessary to make special research on the hybrid Construction machinery while referring to the hybrid vehicle.The paper,by combining the 863 national-level high-tech research and development plan project of “New Hybrid Power Construction machinery Key Technology and System Development”,regards 20 t hydraulic excavators as the research object,according to the load conditions and structure characteristics,makes the special systemic researches for middle-sized hybrid power hydraulic excavators,including the hybrid power system structure scheme design,parameter matching and optimization based on hybrid technology,hybrid power integration energy management strategies,etc.The research contents and progress are as follows:1.It comprehensively compares the advantages and disadvantages of different hybrid power compound patterns and economic costs of components and parts,and reasonably designs the structure schemes of middle-sized hybrid power hydraulic excavators.It makes preliminary parameter design for the main parts of hybrid power system in the theoretical formula calculation and working condition analysis methods,optimizes the hybrid power integration parameters in the improved PSO-DE algorithm according to the cyclic characteristics of concrete working conditions,improves the parameter matching effects and enhances the system performance.2.It builds the mathematical model for the major power elements of hybrid power excavators,and sets up the excavator hybrid power integration simulation system.To accurately calculate the load power,based on the analysis on negative flow control variable displacement pump working principle,it proposes the duplex-type constant-power variable displacement pump regression predication model based on LS-SVM(least squares support vector machine)algorithm.It regards the load spectrum collected in the actual excavation operation of hydraulic excavators as the training sample,regards the pump discharge pressure,pilot control second pressure and negative flow control pressure as the training model input,regards pump displacement as the output for model building,so as to make the model better applied to the working environment.It optimizes the LS-SVM parameters in the methods of grid search and cross validation,and the findings show that the average accuracy of the model for load power calculation is very high.3.It systematically researches the energy management strategies of parallel hybrid power-train of hydraulic excavators.The improved fuzzy logic torque control strategy and the minimum instantaneous fuel consumption control strategy were proposed.It sets the fuzzy rules and designs the fuzzy controller,to the minimum instantaneous fuel consumption control strategy,the details of the instantaneous fuel consumption algorithm were provided.4.With the modular design philosophy,it independently sets up the hybrid power integration comprehensive test system for middle-sized hydraulic excavators,adopts the electrohydraulic proportion technology to realize the hydraulic simulation load,and accurately reproduces the load spectrum in the operation of hydraulic excavators,so as to compare the effects of different energy management strategies of hybrid power-train.It makes comparative experiment on the test bench,and the findings show that compared with the common hydraulic excavator,the fuzzy logic torque control strategy realizes 8.06% of fuel saving,and the minimum instantaneous fuel consumption control strategy realizes 13.04% of fuel saving.