Flux Weakening of PMSM for Enhancing Torque Tracking

Permanent magnet synchronous motors associated to their drivers are subjected to both current and voltage saturations. Dealing with those limitations is the core of flux weakening problem which aims defining achievable operating conditions. In stark contrast with most of the literature focusing on the steady-state, this paper investigates how current and voltage constraints impact transient as well. In-depth analysis reveals that bounds affecting derivative of torque exerted by the machine are influenced by direct current. This suggests that by assigning proper value to this signal, one can shift torque limits beforehand in direction where high torque demand is expected to occur. Simulations suggest that this “preloading” strategy can indeed enhance torque tracking and help meeting the most demanding specifications. A comprehensive optimization framework for selecting the level of “preload” is also provided.