an investigation of dual stator winding induction machines

3.16 and Figure 3.17. It is found from the simulation that the rotor bar currents are almost
zero under no-load condition. However, under the load condition, the rotor bar current is
closed to sinusoidal waveform.
3.10 Air Gap Field Calculation
Finite Element Analysis (FEA) is the favored method of plotting the magnetic fields
in various parts of electric machines, most especially, the flux density of the air gap. The
calculation time for FEA is long and involved if it is required to generate sufficient
performance data. Using the stator winding and rotor bar currents obtained from the
computer simulation results set forth in Section 8 and the winding functions of the stator
windings and rotor loops, the air gap magnetic field contributions from all the stator
windings and rotor bars can be calculated using (3.31). This approach, augmented with
the B-H curve of the core magnetic material to approximately account for the saturation
of the air-gap flux linkage, enables the estimation of the air gap flux density.
When the machine is running under rated load at steady state condition, at any instant
time, the stator currents and rotor loop currents can be found in the full model simulation.
From the rotor model, the bar current is actually the subtraction of the two adjacent rotor
loops that share that rotor bar.
i b
i x
At an instant time, the phase currents of the ABC winding set are = −1.
03 A ,
= 0.
52 A and = 0.
51 A while the phase currents of the XYZ winding set are given as
i c
= 1.
65 A , = 0.
21 A and = −1.
86 A . Then the total air gap flux density and its
i y
components are shown in Figures 3.18-3.24.
i z
123
i a