A generation step for an electric excavator with a control strategy and verifications of energy consumption

Nowadays with the high fuel prices, the demands for energy saving and green emission of construction machineries, without sacrifice of the working performance, safety and reliability, especially for hydraulic excavators (HYEXs), have been highly increased. As a result, electro-hydraulic actuator (EHA), which is promoted and successfully applied to automobile industry, is recently introduced to HYEXs. The aim of this paper is to propose a new type of excavator - electric excavator (ELEX) - with energy saving capacity using the EHAs. Each of the hybrid actuators is driven by an electric motor/generator for recovering a potential energy or a kinetic energy at the time of lowering or slewing stoppage of the excavator, especially when it includes loads. A 5-ton class excavator including a conventional boom system (CBS) and a hybrid boom system (HBS) is analyzed, developed as an experimental ELEX (EELEX) with its validation model to evaluate the proposed ELEX. The hardware implementation is also presented in this paper. A control strategy for the 5-ton EELEX is built to operate the machine to follow desired performances. Finally, working efficiency and energy consumption of the proposed excavator are clearly investigated through both simulations and experiments on the EELEX.