Position control of permanent magnet synchronous motor via composite nonlinear feedback

A parameterized design of composite nonlinear feedback controller is proposed for typical second-order servo systems subject to unknown constant disturbance and control input saturation. The control law consists of a linear feedback part for achieving fast response, a nonlinear feedback part for suppressing the overshoot, and a disturbance compensation mechanism for erasing the steady-state error. An extended state observer is adopted to estimate the unmeasured state and unknown disturbance. The control scheme is applied to a permanent magnet synchronous motor (PMSM) position servo system, and experimental tests are carried out using a TMS320F2812 DSP board. The results confirm that the servo system can achieve fast, smooth and accurate position regulation, and has a certain degree of robustness with respect to the load disturbance and system parameter perturbations.