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Richard230
15 January 2011, 1405
Bloomberg News reports that Toyota is developing an alternative motor for future EVs that would not need rare earth minerals in the motor. They are doing this because these minerals are at risk of supply disruptions (by guess who). They are working on a so-called induction motor that is lighter and more efficient than the PM motors now in use by the company in their hybrids. John Hanson, a company spokesman, says that their research is at an "advanced stage", but did not say when the new motors would be available.

Rare-earth minerals, such as neodymium and dysprosium are used in motor magnets in the Nissan Leaf, GM Volt, Honda's Insight, Toyota's Prius, as well as mobile phones and rechargeable batteries.

Nuts & Volts
15 January 2011, 1427
Tesla already uses this type of motor. Harder to control efficiently, but it seems like it is perfect for high power applications

Kyle

cycleguy
15 January 2011, 1453
It sounds like they're talking about a simple AC induction motor, nothing groundbreaking about that, we use them all the time, AC15's AC20's etc.

Nuts & Volts
15 January 2011, 1627
^^^agreed.

mpipes
15 January 2011, 1802
since the cost of copper is skyrocketing, with more increases in the next few weeks, might be a good time to find other conductor material. :)

chef
15 January 2011, 1816
... such as room-temperature superconductors? :D

Richard230
15 January 2011, 1920
... such as room-temperature superconductors? :D

I thought room-temperature superconductors had been around for years. At least that is what Popular Science keeps telling me. :)

As far as induction motors go, I also thought they were talking about brush-less motors like the AC series, but I can only assume that Toyota must putting a new spin on these type of motors. :cool: Why else would they be beating their chest about their non-rare earth motor design - unless of course it is to stick it to the Chinese..:eek:

jazclrint
17 January 2011, 1124
Wouldn't aluminum be lighter in that application than copper? There might be some efficiency lost in electrical transmission, but recovered a bit by the weight lost to the total vehicle?

teddillard
17 January 2011, 1133
Aluminum is a bit more than half as conductive if I read this right: http://www.tibtech.com/conductivity.php Also melts at a much lower temp.

Nuts & Volts
17 January 2011, 1135
I think a lot/most rotors on an AC induction motor use aluminum because it is cheaper than copper. I have read that Tesla motors use copper for their motor which does improve the efficiency. I am not sure how much of the rotor is actually part of the "squirrel cage" that becomes magnetized, so im not sure the weight savings is substantial.

I also defend the idea that the more efficient a motor the better your system regardless, because more effecient usually means less amps for the same power. This equals smaller/less batteries and maybe a cheaper/smaller/more efficient controller. It would be interesting to see a study on aluminum versus copper rotors

Kyle

lugnut
17 January 2011, 1328
Aluminum is a bit more than half as conductive if I read this right: http://www.tibtech.com/conductivity.php Also melts at a much lower temp.

Aluminum would have about 60% more resistance than copper. That in itself would likely only translate into a percent or so motor efficiency. However when they design induction motors, they can alter the rotor steel for copper and get a smaller motor size for the same power compared to aluminum. And for the melting point difference: If you come near that temperature in application, you have other problems. The lower melting point of aluminum is a positive when it comes to casting the rotors. Lately, methods have been developed to cast copper rotors which brings down the cost of copper squirrel cage rotors dramatically because it reduces the labor. I think the copper industry has funded that research. Go figure :-)

Nuts & Volts
17 January 2011, 1339
thanks lugnut for putting some things into perspective. Any good links to understanding induction rotor construction?

lugnut
17 January 2011, 1403
thanks lugnut for putting some things into perspective. Any good links to understanding induction rotor construction?

http://www.copper.org/applications/electrical/motor-rotor/pdf/technology_transfer_report.pdf

It even has pictures :-) And I haven't read it, but I might. Looks interesting.

Nuts & Volts
17 January 2011, 1500
Thanks man! Ill read it after work with a couple papers I found. I am pretty familiar with BLDC and PMAC, but induction is still a bit of a mystery. Now after the performance and numbers I am reading that Tesla is getting I am more interested in technology behind it all.

As it seems Toyota is as well :)