DIGITAL AND ANALOGUE SIMULATION FOR DYNAMIC RESPONSE OF THREE PHASE INDUCTION MOTORS

Abstract

The dissertation deals with analogue and digital simul-. ation of three phase induction motors. An analogue model of the induction motor is presented for obtaining the transient torque and currents of the induction motor when switched in from stand still. Instantaneous symmetrical con onent approach is used to obtain the analogue model. Standard integro differen-tial equations of the induction motor based on the above approach have been modified to make them independent of the rotor position angle. In the mdified form the equations involve read, quantities only and can therefore be conveniently used for analogue studies• Induction motor switching transients have been obtained with the help of digital simulation. Making use of the circuit equations of the induction motor based on quadrature component approach, a digital computer programme is presented to obtain the transient currents and torque under dynamic conditions. Switching current transients obtained from digital computer are con ared with the current transients recorded experimentally. Circuit equations have also been developed to represent the machine when one of the primary phases or one of the secondary phases is open. A programme for the solution of these equations has been given. This programme can be used for studying the transients, consequent to accidental opening of either a rotor iv phase# or a supply phase. It can also be used for studying the transients when the motor is run or switched in across a single phase supply, after the rotor has been run up by some external means. Above computer programme of switching transients of 3 phase induction motor has been modified to include the unbalance operation of induction motor. Modified programme represents the unbalance operation of induction motor when one phase of stator or rotor winding is opened.