Low and Zero Speed Sensorless Control of nonsalient PMSM

Abstract

A speed sensorless control of nonsalient PMSM is demonstrated in this paper, where estimated rotor flux is directly utilized, instead of transformation angle. A discrete-time slidingmode current controller in stationary frame with EMF feedforward is employed. The operation at low speed is improved by reducing the disturbance impact. The estimation angle error at zero speed is limited by injecting additional DC current that compensates for the unknown load torque and enables operation at zero speed.