Basics: Alternator

Wind Turbine Works builds axial flux permanent magnet wind turbine alternators developed by Hugh Piggott.

Advantages of the axial flux permanent magnet alternator:

• Easy construction
• No gearing
• No brushes
• Low rpm operation
• Easy low wind startup
• High low wind efficiency

Disadvantages of the axial flux permanent magnet alternator:

• Higher magnet cost
• Greater weight

The magnets are mounted on two steel disks to concentrate and channel the magnetic fields across the stator coils sandwiched between the magnet disks.  If a paper clip will stick to the back side of a steel disk, the steel is not thick enough and magnetic flux is being wasted.  The stators are typically 3 phase, with 3 coils per every 4 magnets, wired in star connection with the wild AC converted to DC using rectifiers.