A Novel Nonlinear Active Disturbance Rejection Controller for Speed Control of Electric Drives

In this paper, a novel nonlinear active disturbance rejection (ADR) controller is proposed for the speed control of electric drives so that a better robustness to parameter variations can be achieved. The nonlinear observer is designed by using the sliding mode techniques. When the nonlinear observer is simplified as a linear one, it is equivalent to a phase-locked loop observer (PLLO). However, compared with the existing PLLO, the proposed observer has two gains with specific physical interpretation, which simplifies the gain tuning process, especially for the nonlinear observer. To alleviate the chattering problem, the fraction power function is employed in the observer and the guideline for parameter setting is present. An experimental comparative study of the linear PLLO and the proposed nonlinear PLLO is provided to show the effectiveness.