New flux weakening control for high saliency interior permanent magnet synchronous machine without any tables

This paper presents a new flux weakening algorithm for high saliency Interior Permanent Magnet Synchronous Machine. The proposed method modifies the current reference not by look-up tables, but by a controller in order to achieve a flux weakening. The current reference modification is determined by the d-q axis current and output voltage using the gradient descent method. The proposed method consists of two part, the determination of the flux weakening region and the current reference modification. The flux weakening region is determined by the angle between the constant torque direction and the voltage decreasing direction, and the current reference is modified by the flux weakening direction and the voltage magnitude according to the flux weakening region. Moreover, this method can be applied to the infinite speed drive system as well as the fininite speed drive system. The feasibility of the proposed method has been verified by the experimental results.