Abstract:
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 ( p ) 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.
