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AC analysis of an Induction Machine

Motors and generators with MotorSolve

AC analysis is similar to the equivalent circuit based analysis in MotorSolve IM but is more accurate in that the variations of the lumped parameters at various slips are taken into account. Moreover, MotorSolve IM AC analysis option takes into account regions of linear and nonlinear behaviour of the lumped parameters and automatically adapts to such variations with extra sample points in such regions of the parameter space.

AC analysis can be used to obtain all the standard results that induction machine design engineers are interested in such as torque, efficiency, rms bar, end ring and phase currents and many others. In addition, this is the method that is used to generate shaded and contour plots of various fields such as flux density, current density, flux in phase etc. Some examples of calculations using the AC analysis option in MotorSolve IM are presented below (shown here is the mesh used to compute some of the results presented below of a 17 bar - 24 slot squirrel cage induction machine).

AC analysis using MotorSolve IM

METHODS and RESULTS

AC ANALYSIS RESULTS

As with most analysis options in MotorSolve IM, AC analysis offers a number of typical results of interest that are available to the user with just a click. These include torque, efficiency, power factor, loss components (ohmic, winding, eddy current, hysteresis) at the model component level, current densities (bar, end ring, windings, etc.), etc. In addition, the user may vary the operating point of the machine to study the model characteristics as a function of synchronous speed, rotor slip at various accuracy levels.

TORQUE, OUTPUT POWER PREDICTION with AC ANALYSIS

Torque, output power and efficiency as a function of rotor speed (slip)

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ROTOR BAR LOSSES

Ohmic losses due to bar currents

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EDDY CURRENT LOSS

Eddy current loss distribution predicted by AC analysis in MotorSolve IM.

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HYSTERESIS LOSS

Hysteresis loss distribution of the induction motor with AC analysis.

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CURRENT DENSITY and FLUX LINES

Current density and flux lines of the induction motor using AC analysis.

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