# Induction Motors: A Way Around the Rare Earth Bottleneck



## PhantomPholly (Aug 20, 2008)

Rasor Technologies (http://www.rasertech.com/) was touting a motor like this two years ago - supposedly over 90% efficient and no rare earths. They no longer advertise it on their site so I'm guessing they sold the intellectual property to another company to help refinance their company, which is struggling.

Edit:  As I surmised.

Edit #2. Via Motors


----------



## Coulomb (Apr 22, 2009)

PhantomPholly said:


> Rasor Technologies (http://www.rasertech.com/) was touting a motor like this two years ago - supposedly over 90% efficient and no rare earths. They no longer advertise it on their site so I'm guessing they sold the intellectual property ...


Um, induction motors aren't new. They're about as old as the internal combustion engine; possibly pre-dating it. Please pardon me if I'm misunderstanding your post.

There are millions of industrial induction motors in service all over the world; it's the single largest load on the electricity grid, if I remember correctly. So these are all motors that are over 90% efficient (or very close), have no rare earth magnets, and are cheaper than DC motors (and cheaper than permanent magnet AC motors as well).

The thing holding back induction motors is the AC controller, but you need a similar controller for permanent magnet AC motors anyway. Permanent magnet motors do have a percent or two higher efficiency than induction motors (since you don't have to power the field, except at high speed where you have to use power to oppose the field), so that's why they tend to be used in most commercial EVs. Some exceptions include the Tesla Roadster and GM EV-1. If rare earth magnets become insanely expensive (and I don't see this happening personally), then manufacturers will just switch to induction motors and wear the 1-2% efficiency loss. So the rare earth "bottleneck" is nothing really, unless they really are essential in batteries. But there they are needed in quite small amounts, I believe.


----------



## PhantomPholly (Aug 20, 2008)

Coulomb said:


> Um, induction motors aren't new. They're about as old as the internal combustion engine; possibly pre-dating it. Please pardon me if I'm misunderstanding your post.


You are, but no worries. The big argument against induction motors was that they were not anywhere near as efficient nor capable of producing as much power per pound. Raser, and some others, have found ways to bring new life to an old pony.



> There are millions of industrial induction motors in service all over the world; it's the single largest load on the electricity grid, if I remember correctly. So these are all motors that are over 90% efficient (or very close), have no rare earth magnets, and are cheaper than DC motors (and cheaper than permanent magnet AC motors as well).


Not so much. Efficiency still good compared to ICE, in the 80% range for your typical home heating blower, but weight horrific for the most part.

Tesla and some others like Raser have re-invented the AC motor to make it both more efficient and more energy-dense.

Anyway, that was the whole point of the article too - with which I was agreeing.


----------



## ElectriCar (Jun 15, 2008)

Permanent magnet motors are cool in that they use a magnet in place of the field winding, but a magnet is NOT a necessity in a motor. I always liked them because it eliminates the field winding and the electronics to make power for the winding. 

The one place I can see a problem is replacement motors for CNC machines that use DC servo motors. These things are very prevalent in those machines. If they convert to field winding motors then they have to add the field electronics.


----------

