Disturbancerejection control of AC motor position servo systems
LIU Boyu
(Secondary Vocational Technical School of Hui′an, Quanzhou 362100, China)
Abstract: In order to meet the requirement for accurate positioning in AC motor servo systems with unknown load disturbance, a parameterized composite control scheme was proposed. The scheme was based on the fieldoriented vector control framework for AC motors. Using the torqueproducing current as the control signal(reference input for inner current loop), and the motor angular position as the measurable system output, a parameterized control law was designed, consisting of the poleplacement based state feedback and disturbance feedforward compensation. A reducedorder linear extended state observer was adopted to estimate the unmeasured motor speed and the unknown load disturbance. After software programming in TMS320F28335 DSP, the control law was tested on a permanent magnet synchronous motor(PMSM) servo system, and experimental results verify that the servo system is capable of tracking various target positions smoothly and accurately in the face of unknown load disturbance. The results indicate that the proposed composite control scheme with extended state observer can effectively achieve high performance position regulation in AC servo systems, and have a good robustness against the perturbation in load magnitude and model parameter.
Key words: servo motor; observer; disturbance rejection; composite control; parameterization