Hydraulic spool valve modeling for system level analysis

This paper presents a parameterized, dynamic model of Moog D671 hydraulic servovalve. The valve is a 4/3, center closed configuration. The model is developed based on first principles and is compared to a dynamic model in the form of a Simulink S-function made available by Moog Inc. The model is developed as part of a system level modeling, simulation, and analysis activity at Clemson University's Wind Turbine Drivetrain Testing Facility. The valve model is valuable because the valve is used to control a primary piece of test equipment at the facility and the model will be used for subsequent control system development activities. Results show that the derived model adequately reproduces the behavior of the supplied S-function while offering greatly improved functionality. Additionally, a discussion section address the observed differences between the derived model and the supplied S-function and offers a critique of the S-function's performance.