Numerical Examination of the Performance of an Electrohydraulic System With Discrete Control

The paper submits a modeling approach and numerical simulation results concerning the performance of electrohydraulic power system with discrete control based on a direct acting high-speed servo valve. It is aimed at accounting more accurately for factors with influence on the system performance and efficiency. The possibility for energy recuperation in a hydraulic switching converter is also examined. The modeling approach combines traditional and nontraditional models of the working liquid, connecting pipelines, hydraulic accumulator, hydraulic cylinder and the servo valve. The model of the system is built with the object-oriented modeling language Modelica and simulated in the OpenModelica environment. The results are compared with the results from a traditional dynamic model to assess the significance of factors that are not accounted by the standard linear model. The simulation accounts for factors like nondissolved air content in the working liquid, its variable density, pipe wall deformation and nonlinear hydraulic resistance of the components. The steady state performance of the switching converter is examined.