Process Chain for Quick, Efficient Thermal Assessment with Motor Designs of a Fan

C3 - Motors

For driving fans, electric engines are developed which work in an energy-efficient way and for the manufacture of which resources are carefully used. In order to achieve this and a reduction in cost, the components have to be optimally utilised.
In the development process of electric engines, simulation tools are used for the new designs to enable assessment of a large number of variants as quickly as possible. The operating behaviour of the motor is calculated via a design programme based on Maxwell’s equations. Relevant temperatures are calculated via CFD simulation. The problem here is that losses in the magnetic components depend on their temperature. Motor temperature, however, depends to a decisive degree on the losses occurring. This interdependency has to be taken into account in the design process.
As specification parameters in the development of a fan drive, installation space and desired speed/torque behaviour are usually considered first. Based on them and further parameters, the electromagnetic design tool will yield information on the operating behaviour of the motor, distribution of the losses occurring and the geometry of the magnetically active components. The losses established via the magnetic design are based on assumed, not actual, temperatures.
In case all thermal parameters and the exact loss sources are known, actual temperatures in the motor can be calculated via aero-thermal simulation, yet now the geometry of the entire motor needs to be given. However, the development process at this point in time does not have such a motor geometry yet, so it would have to be constructed now, which would result in a substantial delay of the process. This problem is solved by using a parametric CAD model generating the geometries not coming from the magnetic design (components for mounting or cooling of the motor), and which now, together with the geometries coming from the magnetic design represent the calculation geometry for the aero-thermal simulation. The most important thermal parameters here are thermal conductivity of the materials used and the contact resistances between the individual components.
The aero-thermal simulation yields the temperatures for the components for which the temperatures were assumed in the magnetic design, allowing you to start once more with the magnetic design. If there is a difference between the temperature assumed and the one calculated in a first aero-thermal simulation, the thermal power loss is changed. This in turn changes the temperature distribution of the aero-thermal simulation. The loops are now repeated until there are no further changes in temperature or losses.
This process chain results in an assessment of the operating behaviour of the motor, maximally occurring temperatures and complete motor geometry. The advantage offered by this process chain is the establishment of the ideal magnetic design and thermal optimisation of the motor using the parametric CAD models.