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In this study, the most vital characteristic properties of induction motor, motor starting, maximum and nominal torque are analyzed for what are affected. For the analysis of torque, L type, T type and IEEE 112 equivalent circuit model is employed. Torque change is investigated with the help of codes developed in MATLAB to be used in electrical machines course. First, the slip-moment characteristic curve of the induction motor is divided into three working zones and it was determined which equivalent circuit model gave the best results in these study zones. Later, such parameters as stator and rotor resistance, stator and rotor reactance, magnetization reactance, core resistance and slip are researched for how torque values are affected from. The obtained values for each of the three equivalent circuit models are given and compared with experimental results. 50 HP squirrel cage induction motor parameters are used in analysis. In the analysis, the most influential parameters on the starting torque are found as rotor resistance and stator and rotor reactance. Change of other parameters’ impact ratio depending upon right proportion and inverse proportion is observed. When nominal torque variations are investigated, again rotor resistance is the most influential parameter and by selecting proper factor effecting rotor resistance during design, the result of acquiring desired rotor resistance is obtained. When the maximum torque variations are examined, it appears that the stator and rotor reactance values are effective. Starting, maximum and nominal torque expressions change with square of voltage alters the effect on them a lot. Therefore, triangle or star connection importance arises during machine design.

In the design steps of the induction machines, reducing the power consumption level of the induction machine is a very important issue. Winding topology is one of the most important design parameters for induction machines. Variation of the number of turns in the slots has a significant effect on the performance of the machine. In this study, unlike the studies in the literature, only the number of turns are changed and analyses are performed. Parameters such as stator outer diameter, inner diameter, package length, number of slots, air gap length, coil section and etc. are kept constant. 6 different induction machines which have 6 different winding topologies are designed. 3 of the machines are designed half-coiled and the other 3 machine are designed whole-coiled. Both winding topologies have different turn numbers for a single slot. The turn numbers are 96, 106 and 116 respectively. Noload, locked rotor, and load tests are conducted on these machines. According to the test results and analytical results, performances of the machines are considered. In this way, increasing the turn number for both winding topologies has a decreasing effect on the iron losses of the motor. Similarly, increasing of the stator and rotor resistances directly affects the copper losses of the machine negatively. When considering the efficiencies of the machines, maximum efficiency is achieved for half-coiled 116 turns numbered topology. Similarly, maximum efficiency is achieved for whole-coiled 106 turns numbered topology. [ABSTRACT FROM AUTHOR]

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