Modelling the Processes of Hydraulic Commutation in an Electro-Hydraulic Pumping Unit Driven by an Asynchronous Motor

A mathematical model is presented, describing the small dynamic changes in the operating parameters of the electro-hydraulic pumping unit around an average steady state value. These forced fluctuations are caused by the commutation processes, which equalize the pressure in the working chambers of displacement type hydraulic machine. A block diagram is derived and dynamic structure analysis is conducted. The time and frequency response of the dynamic model are examined numerically, based on experimental data.