• Jun 28, 2011
Most hybrid and electric vehicles rely on rare earth metals. There'd be nothing wrong with that if China didn't supply in excess of 90 percent of the world's rare earth metals. Why is this a problem? Because China's recent decision to slash export quotas on rare earth metals has caused a surge in prices, for one thing.
Building a vehicle like the Toyota Prius requires 20 to 25 pounds of rare earth metals, including two-plus pounds of neodymium. Since China's government is trying to curb exports of rare earths, interest in electric motors that don't rely on rare earth metals has boomed.

One technology – developed by St. Louis, MO-based Nidec Motor – called switched-reluctance motors (SRMs), might offer a viable alternative. SRMs use a variable-speed steel rotor that spins within a housing that contains bundles of wires. Scott Nieberle, vice president of Nidec Motor, says that, "Essentially, you can get the same type of performance without needing to use rare-earth magnets."

The commercial viability of SRMs has increased over the past three decades. In early 2011, John Deere launched two diesel-electric hybrid construction loaders equipped with SRMs. Though SRMs haven't been specifically designed for use in automobiles, Nidec says that it wouldn't take much to make SRMs that compete with rare earth metal-dependent motors used in most of today's electrified vehicles.

[Source: New York Times]


I'm reporting this comment as:

Reported comments and users are reviewed by Autoblog staff 24 hours a day, seven days a week to determine whether they violate Community Guideline. Accounts are penalized for Community Guidelines violations and serious or repeated violations can lead to account termination.


    • 1 Second Ago
  • 19 Comments
      Jorge Pinto
      • 3 Years Ago
      AC induction, Squirrel Cage architecture, gets no more than 80% peak efficiencies, and that requires very tight control of the Slip (the ratio between the field rotation and the rotor rotation speeds). It's usefull for several kW usage (or if you have "cheap" AC voltage available). SRMs are 90+ efficient, in a broad spectrum of rotational speed and applied torque... However, in order to use them comfortably one needs to get rid of torque peaks that occur on pole-teeth alignment. Once you do that, the torque density per Kg is not so great, and while energy efficient, the control electronics are easily 30 to 60% more expensive, compared to 3-phase induction (with slip control). The original article refers/compares to permanent magnet architectures. Regarding these, the sole loss of the SRMs, yet a break/make one, is on Torque/Kg. No one wants to add more Kgs and more complex electronics on an electrical scooter/bike that sells for 500US$ with lead-acid batts.
        porosavuporo
        • 3 Years Ago
        @Jorge Pinto
        What are you talking about ? Induction motor efficiency can certainly exceed 90% , esp with modern FOC and fuzzy logic controls in inverters
          Dan Frederiksen
          • 3 Years Ago
          @porosavuporo
          Dave, Wally is talking about power factor when he says 85%. but he goes on to say that PM is a couple of percent more efficient than AC induction. I'm pretty sure AC induction can be in the 90s.
        leong
        • 3 Years Ago
        @Jorge Pinto
        i can put $1000 down to bet your claim is wrong. Even the cheap IM machines for ventilation systems are rated 85% efficient or better. The IM machine in Tesla definitely can get 90% or above on the efficiency. And don't just look at the "rated" "peak" efficiency, how frequency do you drive at the peak power?
      Nick
      • 3 Years Ago
      Perhaps once we have hundreds of thousands of Hybrids/EVs on the road, old motors could be broken down and recycled for use in the new models.
      Dan Frederiksen
      • 3 Years Ago
      we need room temperature superconductors
        Woody Becker
        • 3 Years Ago
        @Dan Frederiksen
        Hey F, got a degree in electrical engineering? No, I didn't think so!
      Dave R
      • 3 Years Ago
      From the Tesla Motors blog itself which claims 85% peak efficiency for AC induction motors: http://www.teslamotors.com/blog/induction-versus-dc-brushless-motors There is an SAE article which shows the peak efficiency of the Nissan LEAF PM motor in the 95% range. http://www.electricauto.org/resource/resmgr/media/nissan_leaf_sae_2_11.pdf
      2 Wheeled Menace
      • 3 Years Ago
      Another option for non-rare earth containing motors.... excellent! Now if we can only get Bolivia pumping out lithium.. We can break the Chinese dependence. It would bring a tear to my eye to see all the electric drive stuff be produced domestically.
        skierpage
        • 3 Years Ago
        @2 Wheeled Menace
        China has substantial but not huge known reserves of lithium, including deposits in Tibet. The salt plains in Argentina are already pumping out lithium. Bolivia does have huge reserves, but president Evo Morales wants joint ventures to manufacture value-added batteries and vehicles in Bolivia; a noble goal but mining companies prefer simpler regulations. When all these salt brines run out we can extract lithium from seawater. (I'm no expert, this is from reading a New Yorker article months ago.)
      mehulkamdar
      • 3 Years Ago
      While this would reduce the need for Neodymium, that is not the only rare earth or rare metal used in hybrid or pure electric vehicles. You would still need some kind of Lithium combination for the batteries, Samarium, Dysprosium etc for other electronic components and so on. That said, the elimination of Neodymium is a very positive step. Hopefully, this technology will be adopted soon and further research conducted to see how other rare earths and rare metals could be replaced with more common materials. A big thumbs up for Nidec Motor!
      krona2k
      • 3 Years Ago
      What's wrong with ac induction?
        GoodCheer
        • 3 Years Ago
        @krona2k
        Just what I was going to say. It would be great if someone who's job consisted of reporting on green vehicle technologies could develop a slightly more informed and contextualized point of view with respect to the great green myths of our time (Eric).
      Marco Polo
      • 3 Years Ago
      The PRC does not have 90% of the world known rare earth reserves. Bolivia,Argentina, Chile, India, South Africa, Russia, Canada, US, Vietnam and Australia, along with a host of other nations have substantial deposits. The deposits in Australia are potentially larger than PRC, but are in very remote locations lacking mining infrastructure support. Since 'rare earths' are generally not traded on any public exchange, production and pricing are difficult to assess accurately. Some Rare Earths can be very pollutant to exploit. PRC dominance in rare earth production arose due to the ease of access to Inner Mongolian deposits. PRC pricing was aided by a total disregard for environmental issues, and the extensive use of 'forced labour'. These factors allowed the PRC to pursue price dumping policies during the 1990's, in a bid to control the market. With the PRC creating such uncertainty in the market place, mines in other countries attracted little capital investment. Existing mines became uneconomic to operate. The recent change of policy by the PRC to capitalise of this situation, by closing export and raising prices, has seen the reopening of the Mountain Pass mine in California, Nolans Project in Central Australia, the remote Hoidas Lake project in northern Canada, and the potentially vast Mount Weld project in Australia. Hoidas Lake will supply about 10% of North American requirements. Vietnam will supply significant rare earths commodities to Japan from Lai Châu mines. India is ramping up rare earth production for it's own requirements and expects to be self-sufficient within 3 years. More importantly, negotiations are well advanced to allow rare earths to be openly traded, the only stumbling block is the PRC. Despite all this mining activity, it's good to see alternate technology being developed.
        mehulkamdar
        • 3 Years Ago
        @Marco Polo
        Marco Polo, I am somewhat skeptical about how the Indians are going about their work as I do have some experience dealing with them for a client of mine, but yes, the effort to mine rare earths and rare metals is spreading to other parts of the world, and that is a good thing as you point out. It is, of course, even better, that technologies are being developed to reduce their use and to substitute with commonly available materials.
      DB
      • 3 Years Ago
      porosavuporo: Large induction motors in fixed installations certainly can achieve high efficiencies. This is due to the very narrow gaps that can be achieve between the rotor and the stator. In mobile applications, these gaps are necessarily large to keep the rotor from hitting the stator. This leads to notably decreased efficiency when compare to PM motors with similar gaps. The major reason PM motors are used in automotive applications is that they are a lot lighter and more compact than Induction Motors. Just look at the PM motor-generator 2 in the Lexus LS (the high power density automotive motor in production.) Its 165 kW and not much bigger than a coffee can. It achieve 9.9 kW/L and and 3.8 kW/kg, while the Induction motors in GM's 2-mode hybrids are much larger and only 60 kw. Oak Ridge National Laboratory has done a lot of work comparing the best automotive IPM and ACIM motors that is work checking out.
      porosavuporo
      • 3 Years Ago
      Not sure if this will end up in the right place, but thats a reply to Dave R : you must be very confused, you are quoting the number of power factor as a number of efficiency ?? Not much background in EE i assume. Jorge claimed 80% peak _efficiency_, not sure if he meant the motor or the entire drivetrain, but large ACIM motors hit 97-98% efficiencies at high rated loads, with the entire drive system efficiencies exceeding 90% with modern controls. Generally the larger the motor, the more efficient it can be made.
      • 3 Years Ago
      Just to clarify one thing: "St. Louis, MO-based Nidec Motor" is actually Emerson (the same company that has been building electric motors since the 1890s). Nidec bought their motor division in 2010.
      • 3 Years Ago
      Tesla already used AC induction motor in Roadstar.
    • Load More Comments