Position and speed sensorless control for PMSM drive using direct position error estimation

A new position and speed sensorless control approach is proposed for permanent magnet synchronous motor (PMSM) drives. The controller directly computes an error for the estimated rotor position and adjusts the speed according to this error. The derivation of the position error equation and an idea for eliminating the differential terms, are presented. The proposed approach is applied to a vector controlled PMSM AC drive and phase locked loop (PLL) control is employed for speed adjustment. Several simulations are carried out. The proposed control scheme is verified by experiments using a 3.7 kW salient pole PMSM.