New High Speed PMSM Flux-Weakening Strategy

High speed permanent magnet synchronous motors (PMSM) are increasingly used in the field of electric traction due to their high mass and power density. Usually the motor is piloted by a vector control associated with a flux-weakening algorithm which regulates the voltage norm. If the critical point is located within the current limit then it is discerning at very high speed to drive the motor with a Maximum Torque Per Volt (MTPV) strategy. In this article we propose to achieve a unified control algorithm to drive the motor theoretically whatever its speed by giving a torque closest to its desired value while respecting the current and voltage limits and minimizing the current used. Consequently, at high speed at full flux-weakening MTPV strategy is applied which comes to modify the saturation of the current reference magnitude given by the torque reference associated with flux weakening strategy. It enables us to have no switch of algorithms, nor Look-Up-Tables (LUT) which are realized by experiments and depend on the motor, and to not introduce additional observers or regulators, while being precise and more robust to parameter variation than a direct calculation algorithm. The performance of this method is analyzed through a simulation.