Research of non-servo valve electro-hydraulic servo system

A new non-servo valve electro-hydraulic servo system was researched. To control load, the system uses bidirectional fixed displacement hydraulic pump that is driven by AC PMSM directly drives servo-hydraulic cylinder. The hydraulic actuating unit was designed base on one design parameter and performance target. Initiative oil supply issue of closed circuit was solved by a set of screw-in cartridge check valves and closure oil tank contained PAF breather filter were used in the system. Achieving position control of the system by using compound control scheme of feedback-plus-feedforward and pressure closed-loop. The result of the simulation analysis and experimental research showed that the new type system could replace traditional Electro-Hydraulic servo system by achieving the function of controlling the main engine. Because of its closed circuit construction, the system has some new advantages, such as saving space and cost, saving energy sources and environmental protection, all these advantages make it accord with the direction of the future hydraulic technology.