Investigations on Direct Rotor Current Estimation for Vector Controlled Induction Motor Drives

Induction machines are the starting point to design an electrical drive system which is widely used in many industrial applications. Vector control strategy can be applied to this electrical motor type in symmetrical three phase version or in unsymmetrical two-phase version. This paper demonstrates the implementation of field-oriented control and rotor current estimation of an induction machine. The implementation of estimation approach has demonstrated the design of control with observer flux using only the stator currents and voltages measurements. The rotor current is derived in rotor field oriented reference frame. A mathematical model of rotor current and magnetizing current observer was developed in Matlab/Simulink. No load test and blocked rotor test were performed on the wound rotor induction motor to determine the equivalent circuit parameters of the induction motor. Simulation results show that observer can produce well the rotor current estimation. The main objective is to study the behavior of the stator and rotor current in different reference frame under different loading and rotor fault condition. The discrete simulation is done in this paper which gives voltage, torque, current and flux output waveforms.