Initial situation:
A Tier 1 supplier of electric powertrains for electrified vehicles requested Brockhaus expertise in magnetic testing to evaluate the effects of different manufacturing processes on magnetic properties, such as power loss and permeability, of their stator cores. These magnetic properties are of great importance to electric motor designers and producers, as they directly affect the main motor parameters including efficiency, operating temperature and torque/speed characteristic.
Solution:
- Magnetic measurements were carried out on stator cores using the BST-M testing method to investigate the impact of various stator stacking processes, such as bonding, TIG welding, laser welding and interlocking
- Magnetic tests were performed on stator cores using the BST-L system to quantify the influence of stamping on stator teeth and back iron
- Brockhaus BST-M and BST-L technologies were used to evaluate the stress-relief effect of annealing process on magnetic properties of stator cores
- Brockhaus BST-L system was used to measure the deterioration of magnetic properties of stators after heat shrink fitting of the aluminium housing
Result:
- The results from magnetic testing of multiple stators with Brockhaus BST-M and BST-L technologies supported the customer decision on selection of optimal stacking method for their lamination stacks
- The manufacturing induced changes in magnetic properties of stators back iron and teeth were implemented in the electromagnetic modelling of electric motors enabling more accurate prediction of their performance
- The beneficial influence of annealing process on stators magnetic properties was confirmed. The quantitative and qualitative effects of this heat treatment were successfully evaluated with Brockhaus measurement methods
- The BST-L stator tests revealed a highly detrimental impact of radial compression, applied by the aluminium housing, on the magnetic properties of stator cores. This led to further analysis on the improvement of parameters for heat shrink fitting process