Heat Transfer in a BWM Motor

This case study is provided gracefully by SZE University in Györ (Hungary). Many thanks to Zoltan Horvath, Lotfi Abdelhakim.

1. Running the case

The command line to run this case is

mpirun -np 30 feelpp_toolbox_heat --case "github:{repo:toolbox,path:examples/modules/heat/examples/motor}"
Case option
--case "github:{repo:toolbox,path:examples/modules/heat/examples/motor}"

2. Data files

The case data files are available in Github here

3. Main Objectives

The main objective of this case is to develop a thermal model for finding the temperature distribution of different components of an electric motor during its various operating conditions and to determine the heat removal by natural convection from the machine surface.

The application allows the predictions of simultaneous heat transfer in solid and fluid media with energy exchange between them. The prediction of the temperature distribution inside an operating electric motor is required at the machine design stage. Excessive temperature in the motor can cause electrical insulation failure, demagnetization of the magnets and increase in Joule losses.

4. Geometry

Fig.1. Temperature test set up for the prototype machine.


As shown in Fig. 1, the electric motor model has a very complicated geometry. Obviously, it is not possible to perform simulation on the entire PM motor, due to the large number of volumes and calculations required. Therefore, a part of the PM motor consisting of each part (front cover, stator core, stator windings, rotor, permanent magnets, shaft, external housing and the air-gap between these components are modelled for this study as shown on the Fig. 2. Fig. 3. shows a detailed view of the main components of the modeled electric motor.

cad view
Figure 1. Electric Motor Geometry
cad exploded view
Figure 2. Exploded view of the components of the motor

Model detail includes; (1) the front cover, (2) and (5) the external housing geometry, (3) the stator core geometry including slot detail and the stator windings, (4) the rotor geometry including permanent magnets and shaft. In order to simplify the model, the winding region was modeled as a solid section and the end winding region was modeled as a torus. This assumption made this motor element easier to mesh.

As shown in Fig. 4, the mesh for the motor and the air-gap was created based on tetrahedral elements, as these are the only elements capable of meshing that domain.

Figure 3. A general view of the final
Figure 4. A cut-view of the internal air-gap section
Figure 5. Internal air-gap section

5. Input parameters

  • describe the input parameters

5.1. Model & Toolbox

  • describe briefly the model

  • toolbox: give toolbox name

5.2. Materials

describe materials

5.3. Boundary conditions

describe set of boundary conditions

6. Outputs

describe the output set of the example

6.1. Fields

add scalar vectorial and matricial fields to be visualized

6.2. Measures

add measures e.g. scalar quantities, mean.min,max values, norms, error norms, performance metrics

7. Numerical Experiments

Table 1. Temperature distribution in the motor