In this paper, the dynamic performance of an unconventional two-spool flow control servovalve using a pressure control pilot is analyzed. Such valves are less expensive than typical servovalves but also tend to be limited in their dynamic performance. Based on a previously developed eight state nonlinear model, we develop a simplified linear model which is able to capture the essential dynamics of the valve. Using root locus analysis method, the limitation in dynamic performance is shown to be due to a “zero” introduced by the structure of the interconnection of the subsystems. Design parameters that move the zero further to the left half plane, and do not adversely affect other steady-state criteria are identified. The effectiveness of these parameters to improve the dynamic performance is demonstrated. This analysis demonstrates how the structure of the interactions between subsystems in a dynamic component, such as a hydraulic valve, can critically limit the dynamic performance of the component.

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, and
Perry, Y.
, “
Mathematical Modeling of a Two Spool Flow Control Servovalve,” (published in this issue
ASME J Dyn. Syst., Meas., Control
), pp.
. Also in Proceedings of the ASME Dynamic Systems and Control Division, IMECE Orlando, FL., DSC-Vol. 69-1, pp. 321–328.
Lin, S-C. J., and Akers, A., 1990, “Modeling and Analysis of the Dynamics of a Flow Control Servovalve That Uses a Two-Spool Configuration,” Proceedings of the ASME Winter Annual Meeting, Vol. WA90/FPST-3.
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