The idea behind it is over 100 years old
DYSPROSIUM and neodymium are not exactly the best-known elements in the periodic table, but for makers of high-end electric motors they have become vital. Both are strongly magnetic and thus crucial to the construction of powerful motors of the sort used, for example, in electric cars. Unfortunately, they lurk in the part of the table known as the rare-earth metals and, as that name suggests, workable deposits of them are scarce. At the moment, the main source of supply is in China, whose government has used its near-monopoly to restrict availability and push up the price. So there is a lot of interest in inventing motors that can do without them. And several groups of researchers think they have come up with one.
The device in question is known as a switched reluctance motor. The idea behind it is over 100 years old, but making a practical high-performance version suitable for vehicles has not been possible until recently. A combination of new motor designs and the advent of powerful, fast-switching semiconductor chips, which can be used to build more sophisticated versions of the electronic control systems required to operate a reluctance motor, is giving those motors a new spin.
One of the leading contenders is Inverto, a research and development company based in Ghent, Belgium. Inverto’s engineers, led by John De Clercq, the firm’s research director, are collaborating with the University of Ghent and the University of Surrey, in Britain, and also with an unnamed carmaker. They already have a motor running in a car. At Newcastle University, also in Britain, researchers are working with several companies to produce reluctance motors for both cars and lorries. And studies are being carried out in America and Japan too. A team led by Nobukazu Hoshi of the Tokyo University of Science, for example, has experimented with a reluctance motor in a Mazda sports car.