Development of friction compensation control and application to fuel valve control systems

This research involved the design of a position control system, based on a new method of observer-adaptive friction compensation, for a fuel valve that controls the flow of gas in large turbines. This fuel valve is operated by a Permanent Magnet Synchronous (PMS) motor, which is attached to the gear box and coupling joint. These unsatisfactory position response problems that occur at start-up and during operation when the pressure difference (Deltap) across the valve, and consequently the friction, is the greatest includes the following: high overshoots, high steady-state error, and limit-cycle exhibition during steady-state conditions. The deficiency of the linear-based control system of the PMS motor to compensate for the nonlinearity of the system, such as friction effect and flexibility of the coupling joint, is the major source of problems with this fuel valve.; This research developed the fundamental concept of a new observer-based adaptive friction compensation for multibody actuation systems (n degrees of freedom) for both deterministic and stochastic systems, and presents the mathematical equations for molding the nonlinear system, including modeling of the PMS motor, nonlinear actuator, and gear box with friction and flexible coupling joints. Two new methods of compensating for friction, including friction compensation gain and observer-based adaptive friction compensation for a multibody system, are proposed, and the application of the latter is used for improving the position control system of the fuel valve. The initial results of using the new position control system based on observer-adaptive friction compensation have shown improvement to the response of the fuel valve system, both in steady-state and transient operations.