View Single Post
Old 01-05-2009, 04:04 AM   #2 (permalink)
Wannabe greenie
Join Date: Aug 2008
Location: Yorba Linda, CA
Posts: 1,098

The Clunker (retired) - '90 Honda Accord EX sedan
Team Honda
90 day: 29.49 mpg (US)

Mountain Goat - '96 Ford Ranger XLT 4x4 SuperCab
90 day: 18 mpg (US)

Zippy - '10 Kymco Agility 125
90 day: 65.03 mpg (US)
Thanks: 5
Thanked 53 Times in 40 Posts
Originally Posted by The Atomic Ass View Post
As my signature shows, I am an ASE certified day-dream engineer.

I'm always dreaming of making things better. Anywhere fat can be trimmed I process it in my mind. And this time, the issue of controller efficiency is on my mind. And the idea rests upon the restructuring of the motor. Although this is sprung from the hub motor topic in EC, I felt it went a different enough route to warrant a separate topic.

Imagine for me if you will, the permanent magnet motor. As I recall, it has several sets of windings, and only one or perhaps 2 windings are activated at any given point by the brushes. (I use a brushed motor for this example as I've only just as I'm writing this topic looked up how a brush-less motor works, and the concept has not yet sunk in).

My idea is, in the case of a hub motor, wherein there would not be a driveshaft, rather, the whole front face and outer circumferential face, (think of it like a brake drum), would rotate, while the coils would fixed. Now lets say that while the case materials are rated for the motor to put out 10hp, each coil only provides 1hp.

Now, in this case, each coil would consume ~770w. Which I believe is switchable at reasonably high voltages without significant arcing. So now the controller, instead of firing mosfets to control motor current draw, fires relays, to activate or deactivate windings based upon load demand.

Obviously this would require a motor re-designed from the ground up, but sometimes that's not a bad thing. Now anyone with some real credentials want to poke holes into my daydreaming?

</3am half-awake ramblings>
DISCLAIMER: I have no credentials.

You would have 10 pairs of wires into the motor, or can you use a common ground return? Also, how many times can a relay switch 770w before burning up, and can it switch quickly enough? I imagine you'd want to use mosfets anyway, since they're solid state.

If you'd like, I can post your idea to the EVDL and see what the credentialed folks say. (Too bad we can't get Jim Husted to be a regular contributor here; he's a master motor modder.)

  Reply With Quote