Trajectory Planning for Fast Dynamic One-Loop Flatness-Based Control of PMSMs

Permanent magnet (PM) motors are widely used in numerous industrial applications. Although the traditional proportional-integral (PI)-based field-oriented control (FOC) remains the most prevalent control method in industry, it has certain limitations. These include difficulties in handling system nonlinearities during constant changes in operating points, overlooking the saturation effects in permanent magnet synchronous motors (PMSMs), a trade-off between reference tracking and disturbance rejection, and limited dynamic performance due to its cascaded structure, particularly in fast-dynamic applications. Among the proposed nonlinear control methods for PMSMs, flatness-based (FB) control has demonstrated excellent performance in terms of reference tracking, disturbance rejection, and adaptability to saturation conditions. However, most FB control methods in the current literature utilize a cascaded structure to ensure system protection. To enhance one-loop FB control for applications requiring high dynamic performance and precise reference tracking, in this paper, a novel trajectory planning method is proposed to enable one-loop FB control for PMSM drives. This method considers system limits, such as current and switching voltage limits, during trajectory planning. The proposed method offers the advantage of relatively low computational requirements, allowing updates to be made in each switching period. The performance of the proposed method has been validated through both simulation studies and experimental tests on a dedicated testbench. The main novelty of this paper is the introduction of a new trajectory planning method for FB control of PMSMs. Unlike conventional cascaded structures, the proposed approach enables one-loop control while addressing the overcurrent limitation issues typically encountered in one-loop systems. This makes the method particularly suitable for applications that require high dynamic bandwidth, thanks to its simplified one-loop structure.