Efficiency of direct driven hydraulic drive for non-road mobile working machines

As answer for tendencies for compact and powerful solution for electro-hydraulic systems, this paper investigates directly driven hydraulic setup for non-road mobile machinery (NRMM) application. The control of the system is implemented directly with a servo motor drive without conventional hydraulic control valves, which allows accurate control and regeneration. Speed of the double-acting cylinder is determined by in-coming oil flow from the pump, out-coming flow to the hydraulic motor and angular speed of the electric motor. The paper provides a detailed analysis of the system and an evaluation of setup usage for NRMM application. Finally, possible improvements of the suggested system are discussed.