Electrical model for squirrel cage induction machines (EL.SCIM)


The electrical module EL.SCIM for SCIM calculates the following quantities:
- stator and rotor currents
- magnetizing current
- average electromagnetic torque and power
- power factor and efficiency These calculation are done using an equivalent electrical circuit extended to all harmonics.

The elements of the equivalent circuit are
- stator and rotor resistances including skin effects and harmonic slip effects
- stator and rotor leakage inductances including skin effects
- magnetization inductance, including saturation effects
- iron loss resistance

The stator resistance is calculated using analytical geometrical model of the stator conductors, handling both random and formed windings, and any winding type. Some analytical skin effect factors are used depending on the conductor shape and arrangement.

The rotor resistance is also calculated using analytical models. The skin effect in squirrel cage bars can be calculated analytically or numerically. In that case, any rotor slot shape is handled for mold rotors.

The zig-zag and differential inductances are calculated analytically. The stator and rotor leakage inductances can be calculated analytically or numerically using FEMM.

The magnetization inductance can be either calculated analytically, using a saturation coefficient, or numerically using non linear magnetostatic simulation under FEMM. The saturation coefficient is calculated by applying the Ampere law along an average flux line and its calculation handles any slot shape.

The saturated B(H) curve can be defined using numerical values in a .txt file, or using an analytical model. The analytical model can be fit to a given B(H) curve using a GUI interface.

All the parameters of the equivalent circuit can also be enforced by the user.

Application to e-NVH

The electrical circuit is useful when the noise and vibrations due to PWM has to be quickly estimated.


Several validations can be found in the electrical part of validation cases, such as:

Plot commands

To plot the equivalent circuit parameters the following plot commands are available:

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