Sept 21, 2011
A project to replace expensive and environmentally damaging rare earth metals in electric vehicles with steel has received £518,000 to commercialise its technology.
Researchers at Newcastle University have developed an EV motor that generates almost as much torque as existing models, but without rare earth metals such as neodymium and dysprosium that are increasingly costly and difficult to mine.
The Technology Strategy Board has awarded the university, along with Cummins Generator Technologies and motor control manufacturer Sevcon, a grant to scale up the motor for use in hybrid electric trucks.
‘The term “rare earth” is a bit misleading but the problem is they’re very difficult to extract — it’s the sort of thing where they take the tops off mountains,’ James Widmer of Newcastle’s Centre for Advanced Electrical Drives told The Engineer.
’One of the most abundant elements on the planet is iron so the more we can use the better. This technology does away with the [rare earth] magnets completely and just uses electrical steels to produce the force.’
Existing EV motors use rare earth metals as very strong permanent magnets that force the rotor to spin when an electric current is applied to it.
Newcastle’s design makes use of a switched reluctance motor where the magnetic force is created by running current through a series of wire coils that form a circle around a steel rotor. As each coil is turned on and off, the rotor realigns itself with the new magnetic field, causing it to spin.
The team has drawn on its previous research into segmented rotors and simpler electronic control systems to increase the motor’s torque by between 50 and 70 per cent compared to the original technology. It now needs to package it ready for use in electric vehicles, beginning with a hybrid truck by 2014.
‘The challenge is to do it in a way that doesn’t end up creating a lot more loss through heat than you would with a permanent magnet,’ said Widmer. ‘We need to scale this up in a way that is really robust. As you scale up, the forces involved become much greater so you’ve got to make sure it’s mechanically up to the job.’
Because the switched reluctance technology can get hotter than permanent magnet-based motors without demagnetising, the team also hopes to use the same cooling system for the motor as for the engine and the electronics, instead of needing three separate systems.
Demand for rare earth metals has soared over the last decade as they form a key part of current green technologies such as EV motors and wind turbines, as well as many electronic devices including laptops, smartphones and flat-screen TVs.
This has led to huge price rises, with some elements increasing up to 10 times in cost between 2009 and 2010, partly because China produces up to 97 per cent of the world’s supply of rare earth metals and is restricting their supply.
‘We were trying to order magnets recently for another project and could only get a fixed price from the suppliers for one day, whereas normally for a commodity you might be able to get a price for a month or two or even a year,’ said Widmer.
The production of rare earth metals also has a hugely negative impact on the environment, partly because they are often found with radioactive materials and are refined using toxic chemicals, and partly because of lax regulation and illegal mining that has led to severe land and water pollution.
Source: The Engineer
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