U.K. Group Aims to Develop Lower-Cost EV Motor

Researchers in England have launched a three-year effort to develop a switched reluctance traction motor that is quiet enough for use in luxury hybrids.

The $2.3 million effort, which is co-funded by the U.K.'s Technology Strategy Board, will be led by Cobham Technical Service plc. The firm will develop special software to simulate and analyze virtual motor designs. Cobham's partners Jaguar Land Rover and Ricardo UK will design and produce a prototype motor.

Today's electric traction motors use permanent magnets containing neodymium-iron-boron and samarium-cobalt. The partners note that the cost of rare earth elements in such motors has surged by a factor of 10 in recent years.

Switched reluctance motors don't use permanent magnets, and their rotors carry no windings. They produce torque through the magnetic attraction of steel rotor poles to stator electromagnets. The electromagnets switch on and off to "pull" the rotor poles from one stator pole to the next.

Such devices are simple, durable, efficient and able to tolerate high temperatures. But they also require electronic control to avoid "torque ripple" variation between maximum and minimum torque during each revolution that produces noise.