The ultimate feature of every electric motor, be it a direct current type or an alternating current type is its torque (T) and speed (ωm) production capabilities. They are the yard stick upon which the machine is measured. The output characteristics (such as output torque, output power, power factor and efficiency) of all induction motors, whether squirrel cage or wound rotor type are much superior to that of three-phase transfer field motor of the same size and rating, and operating in the asynchronous mode. These are the attributes of the fact that; the losses taking place in three phase induction motors are less in percentage compared to their output. Thus, the efficiency of three phase induction motors is quite high of the order of 80 to 90 percent (V. N. Mittle and A. Mittal, 2008). Also the power factor of an induction motor depends upon the magnitude of magnetizing current drawn by the motor. The magnetizing current in case of three-phase induction motor may be of the order of 20 to 25 percent. As such, the power factor of all three phase induction motor is high. More-still, a three phase induction motor does have starting torque, because there is a rotating field at stand-still produced by three phase starter winding. Moreover, it is possible to increase the starting torque in this case by increasing the rotor resistance (as applicable to wound rotor induction motors). Various leakage fluxes such as slot leakage flux, skew leakage flux, zig-zag leakage flux and end leakage flux etc, responsible for leakage reactance are taken care of and are minimized for a minimum loss, for a boost in motor?s output characteristics. In the case of squirrel cage motors, it has a smaller rotor overhang leakage, which gives a better power factor, a greater pull out torque and over load capacity. In a bid to achieve the afore-mentioned, the dynamic/steady-state analyses of the machines were made by transformation of the machine?s parametric equations in a - b - c reference to arbitrary d-q-o reference frame from which its output characteristics equations necessary for the equivalent circuits/Matlab simulation/plots were achieved.
Induction motor, a-b-c/d-q-o reference frame, dynamic/steady state model, equivalent circuit
Obute K. C. , Olufolahan Oduyemi , Okozi S.O "A Novel Three Phase Induction Motor - Analysis Of Its Performance Indices" Iconic Research And Engineering Journals Volume 3 Issue 9 2020 Page 225-241
Obute K. C. , Olufolahan Oduyemi , Okozi S.O "A Novel Three Phase Induction Motor - Analysis Of Its Performance Indices" Iconic Research And Engineering Journals, 3(9)