Energy efficiency optimization of electric hydraulic loader with variable speed variable displacement power source

An independent pump-controlled hydraulic system based on a variable speed variable displacement power source (VSVDPS) can eliminate throttle losses of the electric loader boom and recover gravitational potential energy. However, challenges arise in efficiently and rapidly solving for the optimal speed and displacement due to severe load fluctuations, model inaccuracies, and the coupling of the two variables. This paper proposes an energy-efficient optimization method based on the model search combined method (MSCM), which leverages the advantages of the model-based method for fast solution finding and the search-based method for high precision. Initially, the model-based method is used to determine the suboptimal speed. Subsequently, based on this speed, the initial speed search interval containing the optimal speed is calculated, enabling the VSVDPS to quickly operate near optimal efficiency during the early stages of the search. Finally, the search-based method is employed to swiftly determine the optimal speed and displacement. The experimental results demonstrate that the MSCM achieves significant energy efficiency improvements with short convergence times. In the hydraulic system of the loader boom, the VSVDPS employing the MSCM reduces energy consumption by 9.38 and 11.27% compared with a variable speed fixed displacement power source and a fixed speed variable displacement power source.