22 Jul 2024


Synchronous reluctance EV motor avoids rare earths

A UK consortium has developed an 85kW synchronous reluctance motor designed primarily for electric vehicle traction applications. The motor, which avoids the use of expensive rare-earth elements, is said to deliver uncompromised performance at a low cost.

The prototype motor has been designed and built as part of a collaborative research and development project, called RapidSR (Rapid design and development of a Switched Reluctance traction motor), led by Cobham Technical Services, and including Jaguar Land Rover and the engineering consultancy, Ricardo. The project is being co-funded by the UK innovation agency, Innovate UK.

The motor has a conventional distributed stator winding, but its rotor is made from cut-steel laminations, which direct and focus flux across the air gap. By maximising this flux linkage between the stator and rotor, performance can be optimised in a tight, lightweight package that does not need rare-earths.

The design uses low-cost materials, simple manufacturing processes and an uncomplicated construction. The prototype has been designed using Cobham’s Opera CAE (computer-aided engineering) software, and built by Ricardo.

“As the market for electric vehicles grows globally, there is an imperative to explore alternatives to permanent magnet traction motors which require the use of expensive, and increasingly difficult to source, rare-earth elements,” explains Paul Rivera, managing director of Ricardo’s hybrid and electric vehicle systems business.

The prototype, he adds, “demonstrates what can be achieved by using the latest electric machine design processes in the creation of a high-performing, compact, lightweight, and rare-earth-element-free concept.”

Since the RapidSR project started in 2012, it has been researching the design of next-generation electric motors that avoid the costly, and potentially difficult-to-source, rare-earth elements that are usually needed for high-power permanent magnets. Using CAE-led design processes and prototypes, the team has created a framework for the future design and manufacture of EV motors that, it says, will offer the performance, compact packaging and light weight needed for use in EVs, but at a much lower cost than permanent magnet machines.

“By bringing together state-of-the-art simulation technology with advanced electric machine design, we have created a highly credible, next-generation EV motor concept that shows considerable promise,” says Dr Will Drury, team leader for electric machines and power electronics at Ricardo.

The prototype “will be rigorously tested over the coming weeks in order to validate the extremely positive results that it has shown in simulation, as a concept that provides an exceptional balance of performance, compact package, light weight and low cost,” he adds.