A novel initial rotor position alignment method for permanent magnetsynchronous motor using incremental encoder

Abstract

This paper presents a new method for the alignment of the rotor of permanent magnet synchronous motors with the phase axis of the stator during start-up. Once the rotor alignment is achieved, the real rotor position angle can be measured by using an incremental encoder and this value can be used in the field oriented control of the motor.Typically, a current is forced into the q-axis. In the proposed method a current is formed in the d-axis instead. Rotor alignment with the phase axis is achieved without any sudden motion by using a PI controller in the current loop.Preventive measures for exceptional situations that may occur during the application of this method are also discussed.Experimental results show that the performance of the proposed method is very satisfactory.