Development of Simulation Models of Induction Squirrel Cage Motor for Varialble-speed Applications

Complex analysis of operational regimes of induction squirrel cage motor is performed. First mathematical model for calculation of motor’s operational characteristics in FORTAN is developed. As a result of developed model motor’s static characteristics of electromagnetic torque , current , speed and power factor are calculated. Further on, motor operating regimes when motor is fed by voltage inverter are analyzed and for this case motor static characteristic of electromagnetic torque is plotted. SIMULINK is used for developing motor simulation models for both cases, when motor is supplied with sinusoidal power supply as well as when it is fed by a voltage inverter. Obtained simulation results for symmetrical sinusoidal power supply are compared with data from the producer showing reasonable agreement. Different operating regimes of motor fed by voltage inverter are analysed: with increased and decreased frequency compared to the rated one while motor flux and electromagnetic torque are maintained constant. In both cases when motor is fed from voltage inverter with increased and decreased frequency compared to the rated one, obtained results of speed and electromagnetic torque are showing good agreement with expected results from analytical calculations