Overview
|
In the induction motor, current is induced in the rotor cage by the rotating
magnetic field of stator coils, causing the rotor to turn. Induction motors
are widely used from industrial machines to home appliances since they
are small, light, affordable, and maintenance-free. Analyzing the current
induced in the rotor bars is important since the induced current essentially
determines the performance of the induction motor. This note presents the
use of magnetic field analysis to obtain the current density distribution
and the speed-torque curve of a three-phase induction motor. |
Current Density Distribution
|
Figure 1 shows the current density distribution at 1050 rpm. Current is
induced in the rotor cage by the rotating magnetic field of stator coils.
This induced current generates magnetic flux, which produces torque by
interacting with the rotating magnetic field. So the induced current has
a large effect on the torque characteristics. |
Speed-Torque Curve
| Figure 2 shows the speed-torque curve. For this induction motor, the maximum
torque can be obtained at the lower speed range. This means the induction
motor has high resistance. In this case, changing the thickness of bars
can reduce the electric resistance, and then the maximum torque can be
obtained at the higher speed range. |
|
|
