An Improved Two-Degree-of-Freedom Speed Controller for Permanent-Magnet Synchronous Motors

For the traditional one-degree-of-freedom controller, there is a trade-off between the tracking performance and disturbance rejection performance. The traditional two-degree-of-freedom controller can achieve disturbance rejection and tracking simultaneously, when there are one tracking channel and one disturbance rejection channel. To overcome the limitations of the one-degree-of-freedom controller and the traditional two-degree-of-freedom controller, an improved two-degree-of-freedom controller is designed for the speed regulation system of a permanent-magnet synchronous motor (PMSM) for use in electric aircraft scenarios and PMSM control applications. This proposed controller includes three elements: a proportional forward element, a proportional–integral feedback element, and a linear extended state observer element. The proportional forward element is used for tracking, and the proportional–integral feedback element and linear extended state observer element are used for disturbance rejection. The controller can simultaneously achieve tracking and disturbance rejection. The proportional forward element guarantees tracking performance, while the proportional–integral feedback and linear extended state observer elements enhance disturbance rejection. The stability of the proposed controller is experimentally demonstrated, and the results show that the improved controller offers superior tracking and disturbance rejection compared to traditional 1-DoF and 2-DoF controllers.