Four-Point Trajectory Tracking Control of PMSMs With Improved Dynamic Response and Steady-State Efficiency

This article proposes a novel four-point trajectory tracking control for permanent magnet synchronous motors (PMSMs) to improve the dynamic response speed performance and steady-state efficiency in full-speed range. In the dynamic process, three points are defined and calculated in real-time, each located within three speed stages, to automatically adjust the current trajectory with maximum torque capability. In the steady-state region, an innovative intersection point is established between the voltage constraint circle and the maximum torque per ampere curve, dividing the minimum copper loss curve into two distinct trajectories. Through comparison with the reference current value, this approach dynamically optimizes the minimum rms value of operating current. The proposed whole current trajectory is constrained by four points with wide universality for various PMSMs, and automatically switched to match the dynamic and steady-state conditions based on the implied speed information from dq-axis currents without extra calculation of turning point in full-speed range. Simulations and experiments are carried out to validate the feasibility and superiority of the proposed current trajectory scheme.