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General Category => Electric Motorcycle News => Topic started by: Michael Moore on July 20, 2018, 10:20:07 PM

Title: A new style of motor
Post by: Michael Moore on July 20, 2018, 10:20:07 PM: http://www.machinedesign.com/motion-control/axial-flux-motors-and-generators-shrink-size-weight

It mentions motorcycles and uses a BMW i3 motor in a comparison with the new design. It sounds very promising, but these things often do.

cheers,
Michael
Title: Re: A new style of motor
Post by: Chocula on July 21, 2018, 06:26:36 AM: I am not sure I read the same article as you. All of the images Google showed me for direct drive washing machine motors appeared to be radial flux, not the axial flux described in article. I also read the statement from the article below to mean that designs that use more copper an bigger magnets cost more money.
Quote
Large machines also require rare-earth permanent magnets and copper for the coils. (According to to Ã–ko-institut e.V, RF DD generators require 600- to 700-kg magnet material per megawatt.) The use of rare and valuable resources has a big impact on the cost and lifecycle analysis of RF DD machines.

This looks like an interesting design and will hopefully help reduce the weight on future motorcycles.
Title: Re: A new style of motor
Post by: Curt on July 21, 2018, 04:36:00 PM: Rare earth shortage spiked in 2011 but seems to have resolved. I didn't realize that.
https://www.technologyreview.com/s/535381/what-happened-to-the-rare-earths-crisis/

The magnetic flux lines they drew seem simplified for both motors. In reality they must contort diagonally as the motor rotates. I didn't see a comparison of how the magnetic forces translate to torque.

With the large dual rotors and double magnets it seems like there would be more rotating mass. Maybe OK for windmills, but could it affect the acceleration and handling in vehicle applications?

It seems like the length of the flux lines would be comparable between RF and AF. Their diagrams show only part of the flux lines. They seemed to imply that the lines would go from one rotor disk through the coil to the other rotor disk, but flux lines must always continue to loop back around.

I didn't understand the 50% wasted loop coils they were talking about for RF.

The claim of 96% better efficiency with "up to 97%" seems excessively precise so that they come across as junk numbers.
Title: Re: A new style of motor
Post by: igorbaldo on July 26, 2018, 11:28:05 PM: Duplicate thread...

http://electricmotorcycleforum.com/boards/index.php?topic=7847.0