A study on full-electric control system of hydro static transmission for construction machines

Full-electric control system of hydro static transmission (HST) was studied. In this paper, system configuration of motor-speed control and control performance were examined through simulation. A simulation model of a HST system was built considering oil-hydraulic components. Especially, a model of a variable displacement pump was built based on experimental data. Transient responses of the HST system were examined and a nominal transfer function was identified which represents typical responses. And a two-degree-of-freedom control system based on the transfer function was applied to control of motor speed. It was demonstrated that control performance was improved under severe conditions.