The stator and lamination stacks
Why stators are built from thin sheets of steel rather than a solid block.
You'll learn
- Explain the stator and lamination stacks at engineering level
- Read the numbers that define the behaviour
- Apply the idea to a real drive unit
Overview
Look closely at any stator and you will find it is not solid iron but hundreds of thin, insulated steel laminations stacked and bonded together — a deliberate design choice to fight a specific loss mechanism.
In depth
A changing magnetic field induces small circulating currents inside any conductor, including the stator's iron core — these are eddy currents, and they dissipate energy as heat. Splitting the core into thin, electrically insulated laminations breaks up the paths those currents can take, slashing eddy-current loss.
| Lamination thickness | Typical application | Relative eddy loss |
|---|---|---|
| 0.5 mm | Grid transformers, 50/60 Hz | Baseline |
| 0.35 mm | Industrial motors | ~0.5× |
| 0.2 mm | High-speed EV traction motors | ~0.16× |
Key takeaways
Remember this
- Laminating the stator core suppresses eddy current losses.
- Thinner laminations are needed as electrical frequency rises.
- Slot and winding geometry trade copper fill against manufacturability and cooling.
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