DYNAMIC D-Q AXIS MODELING OFTHREE-PHASE ASYNCHRONOUSMACHINE USING MATLAB

Abstract

This paper presents a dynamic d-q axis model of three- phase asynchronous motor in synchronously rotating frame. The systems of differential equations representing the dynamic state behaviours of the machine as developed are implemented in MATLAB/SIMULINK. The effects of the stepped sequence of mechanical loading on the motor output variables namely: three-phase stator currents (ia, ib and ic), electromechanical torque and rotor speed, d-q stator and rotor currents (iqs, ids, iqr and idr), d-q voltages (vqs and vds) are examined. The results obtained clearly show the elegance of the d-q axis transformation theory in machine modelling and the inherent limitations of the directon- line starting of 3-hp and 2250-hp asynchronous motors.