Lamination Model (Thermal)

Lamination stacking factors should be set for the stator and / or rotor laminations.

The axial stacking factors for the stator and rotor are entered in the Cooling Options [Input Data Editor] as shown below:

The lamination model assumes that each lamination stack consists of 2 materials: the laminations themselves and the inter lamination material.

The thermal material properties for both materials should be entered in the Materials & Weights input editor.

The Stator lamination material is split between the Stator Lam (Back Iron) and Stator Lam (Tooth) components, as well as Inter Lam (Back Iron) and Inter Lam (Tooth) components for the inter lamination material.

The Rotor lamination material is split between the Rotor Lam (Back Iron) and Rotor Lam (Tooth) components, as well as Rotor Inter Lam (Back Iron) and Rotor Inter Lam (Tooth) components for the inter lamination material.

Lamination Thermal Resistances

Important

The axial thermal resistance value is included in the thermal model only if:

The model has more than 1 axial slice, or
The Improved (Experimental) Interior U-Rotor Thermal Circuit is used.

In all other cases, the axial thermal resistance value is not included. This is to ensure the central temperatures are not overestimated.

Axial Lamination Thermal Resistance Calculation:

Axial Resistance = Axial_Resistance_Lam + Axial_Resistance_Inter_Lam

where:

Axial_Resistance_Lam = Stack_Length x (Stacking_Factor) / (Conductivity_Lam x Stack_Area)

Axial_Resistance_Inter_Lam = Stack_Length x (1 - Stacking_Factor) / (Conductivity_Inter_Lam x Stack_Area)

Important

The radial thermal resistance value is equal to the radial resistance through the steel laminations and the radial resistance through the inter lamination material, in parallel. However, in Motor-CAD, this second term is neglected. The underlying assumption is that the inter lamination material has poor thermal contact, very low thermal conductivity (compared to the steel) and is only a small fraction of the stack length, so has a negligible influence on the radial resistance value.

Radial Lamination Thermal Resistance Calculation:

Radial_Resistance = Radial_Resistance_Lam

where:

Radial_Resistance_Lam is the radial resistance of the lamination material, based on an axial length of (Stack_Length x Stacking_Factor)

Lamination Thermal Capacitances

The thermal capacitance of the lamination and inter lamination are summed to give the capacitance of the rotor and stator.

The weights of each material are specified/can be adjusted using the Materials & Weights editor.