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an investigation of dual stator winding induction machines

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5.6 Computer Simulation <strong>an</strong>d Experimental Results<br />

The computer simulation <strong>of</strong> the conditions in (5.116) in which the slip frequencies <strong>of</strong><br />

the two <strong>stator</strong> <strong>winding</strong>s are equal has been undertaken using the MATLAB/SIMULINK<br />

s<strong>of</strong>tware. The <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine models with a common rotor circuit<br />

<strong>an</strong>d with two independent rotor circuits are used in the computer simulations <strong>an</strong>d the<br />

results are compared to show the differences. Some <strong>of</strong> the calculated machine parameters<br />

used are const<strong>an</strong>t <strong>an</strong>d are given in Table 3.1. The simulation results for <strong>stator</strong>-frequency<br />

<strong>an</strong>d rotor speed condition in (5.116) are displayed in Figure 5.2. The two <strong>winding</strong>s are<br />

fed with two sinusoidal voltage sources <strong>an</strong>d operating under const<strong>an</strong>t voltage/Hertz open<br />

loop control in which the ratio <strong>of</strong> the frequency <strong>of</strong> the 6-pole <strong>stator</strong> <strong>winding</strong> set to those<br />

<strong>of</strong> the 2-pole <strong>stator</strong> <strong>winding</strong> set is equal to 3. The frequencies <strong>of</strong> the ABC (2-pole) <strong>an</strong>d<br />

XYZ (6-pole) <strong>stator</strong> <strong>winding</strong> sets are initially set to be 30 Hz <strong>an</strong>d 90 Hz respectively. The<br />

const<strong>an</strong>t voltage/Hertz coefficient <strong>of</strong> both the voltages supplied to the ABC (2-pole) <strong>an</strong>d<br />

XYZ (6-pole) <strong>stator</strong> <strong>winding</strong> sets is at 2.23. The load torque is 3 Nm. During the steady-<br />

state operation, the frequency <strong>of</strong> the input voltage to the ABC <strong>winding</strong> set remains at 30<br />

Hz, the measured rotor speed is used to adjust the frequency <strong>of</strong> the input voltage supplied<br />

to the XYZ <strong>winding</strong> set to satisfy (5.116) at t =1.5 seconds. If the motor is closed-loop<br />

speed controlled, the input phase voltages <strong>of</strong> the XYZ <strong>winding</strong> set are adjusted<br />

accordingly while maintaining equal slip frequency operation. The same simulation<br />

conditions are applied to both machine models <strong>an</strong>d the simulation results are shown in<br />

Figure 5.2. In this figure, the blue solid line represents the results from the one rotor<br />

circuit model <strong>an</strong>d the red dash-dot line represents the results from the independent rotor<br />

circuit model. The steady state rotor speeds <strong>of</strong> two models are different because <strong>of</strong> the<br />

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