Determination of the optimum steady-state performance of an open-loop and a closed-loop valve-controlled hydro-motor drive: a design approach

This article analyses the steady-state performance of an open-loop and a closed-loop proportional valve-controlled hydromotor drive. The drives considered for the analysis consist of HSLT and LSHT hydro-motors. In this respect, considering the flow and torque losses of the valve and the hydro-motors, the system equations are deduced from the model. They are made non-dimensionalised, from where the expressions of the performance parameters in terms of the speed, efficiency and power transfer of the drives are determined. From the explicit design equations, the conditions for the maximum efficiency and the power transfer are obtained. The drives performances are analysed in both open-loop and closed-loop configurations and compared with the test data. Using the explicit design equations developed from the model, the effects of the losses of the hydro-motors and the control gain on the performance of the drives are studied. Using the simplified set of design equations developed in the model, the drive's performance can be determined within its reasonable operating zone from a limited amount of test data.