Rotor Resonance Disturbance Rejection Controller

A control system is proposed to actively suppress the resonant mode of a rotor drivetrain. A resonant suppression control loop is introduced in parallel with the speed governing control loop. This control loop receives a feedback signal from the free turbine and rotor speed. It then extracts the resonant component from the feedback signal to generate a resonant signal containing the resonant component and estimates a derivative of the free turbine speed from the resonant signal. The control loop outputs a request for damping the resonant mode on the basis of the derivative. A narrow-band reject filter is also introduced in the free turbine speed governing loop to filter out the resonant component from the feedback signal, thereby ensuring that the free turbine speed governing loop does not interfere with the resonant suppression control loop.