Vertically stacked stators and rotors

[verticalSpin]

Greetings, I am working on a design for a vertically stacked stators and rotors permanent magnet alternator. Traditional fabrication techniques fabricate the axial flux design using one stator and dual rotors to create the device. The approach I am experimenting with has 3 stators and 4 rotors on a central axis. Each phase is cast in it own stator which allows for a increased coil count while using less magnets. Some concerns have been made about the effectiveness of this configuration.
1. Is the BH max point affected for the permanent magnet using this configuration.

2. Does the valve of the BH max point even apply to evaluating this device? I interested in finding out if the person presenting opposition to this idea is just adding misleading information to strengthen his point of view. I really do not know and any information would be a great help.

3. Does the coil configuration decrease the effectiveness of the permanent magnet lines of flux to generator current or is it just taking full advantage of what is available.

Comments welcome.

 

[verticalSpin]

Greetings, additional photos of project. Is there away to add more then one attachment to a single post?

 

[verticalSpin]

Greetings, photo of stators being used for project.

 

[electricpete]

Wouldn't you want the stators to be lined up with each other their mmf's tend to reinforce with each other? Why do you suggest a stagger?

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(2B)+(2B)' ?

 

[electricpete]

Also it looks like the rotor is thick metal rings with PM's mounted on them. Why are they so thick?

From a magnetic standpiont, you could reduce the thickness of those metal rings to whatever you need for mechanical strength, as long as you reduce the airgap by the same amount.

By the way I don't know anything about this type of machine... just trying to figure it out.

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(2B)+(2B)' ?

 

[waross]

I hope you are putting iron cores in those coils. For a given magnetizing force, the flux density is inversely proportional to the weighted length of the magnetic circuit. If your magnetic circuit weighted length is doubled with the magnetizing force your flux density will be halved.
But the biggest issue is the weighing. A inch of air in the magnetic circuit is equivalent to several thousand inches of iron.
You want the magnetic circuit from the north poles of your magnets back to the south poles to be as short as possible an although you need air gaps for clearance between stationary and moving parts, air gaps should be as small as possible. Any metal plates which form part of the magnetic circuit must be designed for flux density as well as mechanical strength.

Bill
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"Why not the best?"
Jimmy Carter

 

[verticalSpin]

Greetings, here is better picture of the top and bottom rotors. The metal ring contains the lines of flux and prevents eddy currents from forming on any metal part in close proximity which can cause a undesired breaking affect. When the stators are installed the air gap between the rotors and stators is less then a 1/16 th of an inch. There have been prototypes with metal backed center rotors but the results indicated that the output was not worth the extra effort and it would change the coil configuration. I could wrong but I have not been able find any examples of the proposed configuration. Offset of the stator position is to produce a 3 phase AC output.

 

[waross]

McCulloch chain saws used to make a small single phase generator based on that general principal.
As I remember they spun two flywheels with embeded magnrts about 5/8 inch apart. A pair of flat wound coils and cores were placed between the magnetic flywheels. Turned 3600 RPM and generated about 1000 Watts at 60 Hz. It was horizontal, but the orientation depends on the prime mover configuration.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[sreid]

Take a look at the Bodine E-Torque Motor.

http://www.bodine-electric.com/etorq/

 

[verticalSpin]

Greetings, I had some time to create a visual aid of would I believe the lines of flux may look like when the rotors and stators are stacked vertically.
Stacking the rotors and stators vertically require ½ the magnet count then using traditional fabrication techniques.
Example: 3 phase, 8 coils per phase
Traditional fabrication requires 64 magnets
Stacked Vertical fabrication 32 magnets
Yes, they appear to be very similar to what is being call a axial flux permanent magnet alternator. What I am really trying to find out is does the pull force or flux density accumulate when the magnets are stacked in a vertical configuration even with the added air gaps?