Patent ID: 9223321
Filing Date: 2015-12-29
Classification: G05B,G05D,H02P

Abstract:
1. A system comprising a controlled system and a harmonic controller connected to the controlled system to provide a harmonic control signal to the controlled system for reducing periodic disturbances in a feedback quantity of the controlled system, the system having a plurality of control loops, the harmonic controller comprising for each control loop: a magnitude calculator coupled to the controlled system to receive a feedback signal representative of the feedback quantity and configured to repeatedly calculate a value of a magnitude of a respective harmonic component of the feedback signal; an integrator coupled to the magnitude calculator to receive the repeatedly calculated values, the integrator being configured to sum the received values to produce an accumulated value; a harmonic generator configured to generate a harmonic signal having a frequency equal to a frequency of the respective harmonic component and a phase relative to the respective harmonic component set to compensate for an estimated phase shift produced by the controlled system between the harmonic control signal and the feedback signal at the frequency of the respective harmonic component; a multiplier coupled to the integrator and harmonic generator to multiply the accumulated value and the harmonic signal to produce a generated harmonic component; wherein the harmonic controller is arranged to sum the generated harmonic components to produce the harmonic control signal and to apply the harmonic control signal to the controlled system to reduce the periodic disturbance in the feedback quantity.