High Stability V/f Control of PMSM Using State Feedback Control Based on n-t Coordinate System

This paper proposes a new V/f control method for permanent magnetic synchronous motors (PMSM) without position sensor. The proposed method uses state feedback control based on a n-t coordinate system. The t-axis is a tangent line of a constant voltage ellipse, and the n-axis is a normal line of the ellipse. The t-axis current is utilized to keep the system poles in the stable plane in low speed of motor and to achieve high stability.