New Technology
EMFree
EMFree [Embo-Free] Motor Core
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■ Existing technology [Emboss]
Fastened on the surface of electrical steel in relief
- The amount of embossing needs to be increased to reinforce the clamping force.
- Lower efficiency due to the gap between the embossing and the sheet
- Lower flux density due to the deterioration of the stacking factor caused by the gap between individual sheets
- 5~10㎛ between layers
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■ New technology [Bonding]
Fastened with adhesive between electrical steel products without any relief, welding or rivet
- Greater clamping force and stacking factor than the Embo type
- 10% less core loss than the Embo type
- Over 15% greater flux density than the Embo type
- 2~3㎛ between layers
Characteristics of the EMFree Motor core
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■ Core Loss
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■ flux Density
■ Traction Motor Efficiency
The EMFree type has higher torque efficiency than the Embossed Type in the low-speed section.
■ NVH evaluation
Results from testing of EMFree motor cores for green cars
| Item | EMFree | Embossed Type | Remarks | |
|---|---|---|---|---|
| Core | Stacking force | 74.04[kgf/㎠] | 3.38[kgf/㎠] | |
| Perpendicularity | 0.126 | 0.308 | ||
| Flatness | 0.054 | 0.306 | ||
| Motor efficiency | - | 0.1~0.3%↑ | - | 2.66 → 2.58kg |
| NVH | High frequency | 3~5dB↓ | - | |
| Environment | Adhesive (high temperature) |
62.31 → 14.22kgf | 3.83 → 3.85kg | 160℃, 80min |
| Adhesive(ATF oil) | 10.23 → 7.71kgf | 2.66 → 2.58kg | ATF150℃, 500hr | |
