The general principle behind a permanent magnet generator is to induce a voltage in specifically wound wires via a changing magnetic field.  When this voltage is applied to a load power is produced.  So called “off-the-shelf” generators often lack the power or form-factor desired for customer specific applications.

There are two primary configurations of custom designed permanent magnet generators:
Externally driven rotor
Internally driven rotor

When working with our engineering group, you might be asked:
1.  What power output is required?
2.  What is the required voltage output? (AC/DC and Quantity)
3.  What is the maximum acceptable diameter?
4.  What is the maximum acceptable length?
5.  What is the maximum ambient temperature?
6.  What is the maximum ambient pressure?
7.  What is the desired configuration of your generator? Internal or external rotor?
8.  What is the operating rpm range of the generator?
9.  Will there be shock and vibration during operation?
10. What is the desired “life” of the generator?

Materials
Neodymium Iron Boron can be used for “low” temperature rotor applications.
Samarium Cobalt can be used for “high” temperature rotor applications.
In most applications, a ferrous material will be used for the base of the rotor.
The stator portion will be composed of magnet steel laminations which will be welded into a stack.
The lamination stack is commonly wound with copper wire.
In most applications, the rotor and stator are encapsulated with a thin sleeve of nonmagnetic metal.
The magnets of the rotor assembly are adhered to the base of the rotor.
The stator assembly is often “potted” with an epoxy which is application specific.

Prototyping/Turnaround
The design process for custom generators is very expensive and very timely.  Once all of the design criteria have been established, an initial stator laminate geometry, copper wire diameter and number of windings can be analyzed for power output through the use of Finite Element software.  This analysis will give an estimate of the diameter and length of the finished generator.  If the size constraints meet the customer’s requirements, a prototype can be manufactured.  If the size constraints do not meet customer requirements, diameter and length can be changed by increasing one of the variables to decrease the other.

The manufacturing process begins with parallel paths for the rotor and stator assemblies.  The stator assembly is initiated with the purchase of a laminate stack.  Once received, the laminate stack is sent out to be wound with copper wire.  The rotor assembly process can begin when the magnets are completed.  The magnets are then adhered to the base.

Once the aforementioned steps have taken place, the custom generator may be tested internally to verify voltage output.  If the voltage output meets specification, the finishing manufacturing operations will be completed.  The steps involve epoxy filling of the stator assembly and laser-welding the nonmagnetic protective shields into place on both assemblies.

We will perform testing of prototypes as requested to meet customer specifications.  Some fixturing charges may apply.

Turnaround of the first prototype can range from 12 to 20 weeks.  Turnaround for production quantities of custom generators will very based on tooling and material lead times.