Measurements and Modelling of Low-frequency Disturbances in Induction Machines

Abstract: in this thesis the low-frequency dynamic behavior of the induction machine is analyzed. disturbances in the shaft torque and supply voltage are investigated theoretically, The calculated response to shaft torque disturbances is verified with measurements on a 15 kW machine. Furthermore, the influence of the machine parameters, skin effect and operating point is studied. The results predicted using some models of lower orders are compared with measurements and results obtained by using a two-axis model. The results indicate that a first-order model can be used to determine the dynamic response to shaft torque and voltage disturbances up to one or a few hertz. By using a second-order model also higher frequency disturbances could be treated with a rather small loss of accuracy. The temperature significantly effects the low-frequency dynamics of the induction machine while the influence of skin effect and static shaft torque is of less importance to an ordinary industrial machine.